@conference{feshbach2024kinematicTrees,
title = {Algorithmic Design of Kinematic Trees Based on CSC Dubins Planning for Link Shapes},
author = {Daniel Feshbach and Wei-Hsi Chen and Ling Xu and Emil Schaumburg and Isabella Huang and Cynthia Sung},
year  = {2024},
date = {2024-10-08},
urldate = {2024-10-08},
booktitle = {Workshop on the Algorithmic Foundations of Robotics (WAFR)},
abstract = {Computational tools for robot design require algorithms moving between several layers of abstraction including task, morphology, kinematics, mechanism shapes, and actuation. In this paper we give a linear-time algorithm mapping from kinematics to mechanism shape for tree-structured linkages. Specifically, we take as input a tree whose nodes are axes of motion (lines which joints rotate about or translate along) along with types and sizes for joints on these axes, and a radius $r$ for a tubular bound on the link shapes. Our algorithm outputs the geometry for a kinematic tree instantiating these specifications such that the neutral configuration has no self-intersection. The algorithm approach is based on understanding the mechanism design problem as a planning problem for link shapes, and arranging the joints along their axes of motion to be appropriately spaced and oriented such that feasible, non-intersecting paths exist linking them. Since link bending is restricted by its tubular radius, this is a Dubins planning problem, and to prove the correctness of our algorithm we also prove a theorem about Dubins paths: if two point-direction pairs are separated by a plane at least $2r$ from each, and the directions each have non-negative dot product with the plane normal, then they are connected by a radius-$r$ CSC Dubins path with turn angles $leq pi$. We implement our design algorithm in code and provide a 3D printed example of a tubular kinematic tree. The results provide an existence proof of tubular-shaped kinematic trees implementing given axes of motion, and could be used as a starting point for further optimization in an automated or algorithm-assisted robot design system.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
@conference{xu2024cscDubinsReparameterization,
title = {Reparametrization of 3D CSC Dubins' Paths Enabling 2D Search},
author = {Ling Xu and Yuliy Baryshnikov and Cynthia Sung},
year  = {2024},
date = {2024-10-08},
booktitle = {Workshop on the Algorithmic Foundations of Robotics (WAFR)},
abstract = {This paper addresses the Dubins path planning problem for vehicles in 3D space. In particular, we consider the problem of computing CSC paths– paths that consist of a circular arc (C) followed by a straight segment (S) followed by a circular arc (C). These paths are useful for vehicles such as fixed-wing aircraft and underwater submersibles that are subject to lower bounds on turn radius. We present a new parameterization that reduces the 3D CSC planning problem to a search over 2 variables, thus lowering search complexity, while also providing gradients that assist that search. We use these equations with a numerical solver to explore numbers and types of solutions computed for a variety of planar and 3D scenarios. Our method successfully computes CSC paths for the large majority of test cases, indicating that it could be useful for future generation of robust, efficient curvature-constrained trajectories.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
@conference{unger2024RMBF,
title = {Re-programmable Matter by Folding: Magnetically Controlled Origami that Self-Folds, Self-Unfolds, and Self-Reconfigures On-Demand},
author = {Gabriel Unger and Cynthia Sung},
url = {https://www.youtube.com/watch?v=TuIq6ykfoOA&list=PLmM-rbrIwkWXFno8GbQYxiCcA3s8SaVJW&index=1
https://repository.upenn.edu/entities/publication/18d39cb9-f453-4cc7-9a68-47ddcc4a2924},
year  = {2024},
date = {2024-07-16},
urldate = {2024-07-16},
booktitle = {8th International Meeting on Origami in Science, Mathematics, and Education},
abstract = {We present a reprogrammable matter system that changes shape in a controllable manner in real-time and on-demand. The system uses origami-inspired fabrication for self-assembly and repeated self-reconfiguration. By writing a magnetic program onto a thin laminate and applying an external magnetic field, we control the sheet to self-fold. The magnetic program can be written at millimeter resolution over hundreds of programming cycles and folding steps.  We demonstrate how the same sheet can fold and unfold into multiple shapes using a fully automated program-and-fold process. Finally, we demonstrate how electronic components can be incorporated to produce functional structures such as a foldable display. The system has advantages over existing programmable matter systems in its versatility and ability to support potentially any folding sequence.},
keywords = {2024, magnetic, origami, programmable matter, self-folding},
pubstate = {published},
tppubtype = {conference}
}
@conference{feshbach2024kinegamiPython,
title = {Kinegami: Open-source Software for Creating Kinematic Chains from Tubular Origami},
author = {Daniel Feshbach and Wei-Hsi Chen and Daniel E. Koditschek and Cynthia Sung},
url = {https://github.com/SungRoboticsGroup/KinegamiPython
https://sung.seas.upenn.edu/research/kinegami/
https://repository.upenn.edu/handle/20.500.14332/60333},
year  = {2024},
date = {2024-07-16},
urldate = {2024-07-16},
booktitle = {8th International Meeting on Origami in Science, Mathematics, and Education (8OSME)},
abstract = {Arms, legs, and fingers of animals and robots are all examples of “kinematic chains" - mechanisms with sequences of joints connected by effectively rigid links. Lightweight kinematic chains can be manufactured quickly and cheaply by folding tubes. In recent work [Chen et al. 2022], we demonstrated that origami patterns for kinematic chains with arbitrary numbers of degrees of freedom can be constructed algorithmically from a minimal kinematic specification (axes that joints rotate about or translate along). The work was founded on a catalog of tubular crease patterns for revolute joints (rotation about an axis), prismatic joints (translation along an axis), and links, which compose to form the specified design. With this paper, we release an open-source python implementation of these patterns and algorithms. Users can specify kinematic chains as a sequence of degrees of freedom or by specific joint locations and orientations. Our software uses this information to construct a single crease pattern for the corresponding chain. The software also includes functions to move or delete joints in an existing chain and regenerate the connecting links, and a visualization tool so users can check that the chain can achieve their desired configurations. This paper provides a detailed guide to the code and its usage, including an explanation of our proposed representation for tubular crease patterns. We include a number of examples to illustrate the software’s capabilities and its potential for robot and mechanism design.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
@conference{weakly2024windtunnel,
title = {A low-cost, adaptable system for lift and drag measurement in an educational wind tunnel},
author = {Jessica Weakly and Sarah Ho and Erica Feehery and Bruce Kothmann and Cynthia Sung},
url = {https://sung.seas.upenn.edu/publications/wind-tunnel-force-balance/},
doi = {10.18260/1-2--46453},
year  = {2024},
date = {2024-06-26},
urldate = {2024-06-26},
booktitle = {2024 ASEE Annual Conference and Exposition},
abstract = {Wind tunnel testing augments the undergraduate fluid dynamics curriculum by providing
hands-on application of the course material, and a low-cost version of a force balance is desirable.
To maximize the utility of wind tunnel-based lessons and laboratory demonstrations, there is also
a need for a setup that is easily adaptable to different tests and loading applications. This paper
provides such a force balance design, along with detailed evaluation and benchmarking to
characterize the accuracy of the force balance. Our force balance uses readily available materials
having a total cost under $125. Static load tests show that the force balance is accurate with a
mean absolute percentage error of only 2.5%. We demonstrate the system’s usefulness and
adaptability with classic examples of measuring drag on a sphere and characterizing a
NACA 0012 wing, as well as with measuring lift on a foldable wing. Finally, we pilot the force
balance in an undergraduate mechanical engineering lab setting and find that students are able to
explore the setup, understand the load cell functionality, and use the system to measure drag on a
sphere. The force balance enables students to gain hands-on learning experience related to both
fluid mechanics and statics, and our user study shows that the force balance is durable through
classroom use. The low cost, robustness, and high adaptability of the system makes it suitable for
incorporating in multiple labs or for allowing student project teams to utilize the system in their
own experiments.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
@workshop{chen2024robogami,
title = {Robogami Reveals the Utility of Slot-Hopper for Co-Design of DOQ’s Body and Behavior},
author = {Wei-Hsi Chen and J. Diego Caporale and Daniel E. Koditschek and Cynthia Sung},
url = {https://www.robotmechanisms.org/activities/icra-2024-codesign},
year  = {2024},
date = {2024-05-13},
urldate = {2024-05-13},
booktitle = {ICRA 2024 Workshop on Co-design in Robotics: Theory, Practice, and Challenges},
keywords = {},
pubstate = {published},
tppubtype = {workshop}
}
@article{weakly2024BATb,
title = {Bistable Aerial Transformer: A Quadrotor Fixed-Wing Hybrid That Morphs Dynamically Via Passive Soft Mechanism},
author = {Jessica Weakly and Xuan Li and Tejas Agarwal and Minchen Li and Spencer Folk and Chenfanfu Jiang and Cynthia Sung },
editor = {Ashis G. Banerjee},
url = {https://youtu.be/eDKwBM2RLOg?feature=shared

https://asmedigitalcollection.asme.org/mechanismsrobotics/article/doi/10.1115/1.4065159/1198861/Bistable-Aerial-Transformer-BAT-A-Quadrotor-Fixed
},
doi = { 10.1115/1.4065159},
year  = {2024},
date = {2024-04-24},
urldate = {2024-04-24},
journal = {ASME Journal of Mechanisms and Robotics},
volume = {16},
number = {JMR-23-1641},
issue = {7},
pages = {071016},
abstract = {Aerial vehicle missions require navigating trade-offs during design, such as the range,
speed, maneuverability, and size. Multi-modal aerial vehicles enable this trade-off to be
negotiated during flight. This paper presents a Bistable Aerial Transformer (BAT) robot,
a novel morphing hybrid aerial vehicle that switches between quadrotor and fixed-wing
modes via rapid acceleration and without any additional actuation beyond those required
for normal flight. The design features a compliant bistable mechanism made of thermoplastic polyurethane (TPU) that bears a large mass at the center of the robot’s body. When
accelerating, inertial forces transition the vehicle between its stable modes, and a fourbar linkage connected to the bistable mechanism folds the vehicle’s wings in and out.
The paper includes the full robot design and a comparison of the fabricated system to
the elastodynamic simulation. Successful transitions between the two modes in mid-flight,
as well as sustained flight in each mode indicate that the vehicle experiences higher
agility in the quadrotor mode and higher flight efficiency in the fixed-wing mode, at an
energy equivalent cost of only 2 s of flight time per pair of transitions. The vehicle demonstrates how compliant and bistable mechanisms can be integrated into future aerial vehicles
for controllable self-reconfiguration for tasks such as surveillance and sampling that
require a combination of maneuverability and long-distance flight.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
@conference{misra2024tsmb,
title = {Online Optimization of Soft Manipulator Mechanics via Hierarchical Control},
author = {Shivangi Misra and Cynthia Sung},
url = {https://youtu.be/DS2kEvccwYA?feature=shared
https://repository.upenn.edu/handle/20.500.14332/59590},
doi = {10.1109/RoboSoft60065.2024.10522004},
year  = {2024},
date = {2024-04-14},
urldate = {2024-04-14},
booktitle = {7th IEEE-RAS International Conference on Soft Robotics (RoboSoft)},
abstract = {Actively tuning mechanical properties in soft robots is now feasible due to advancements in soft actuation technologies. In soft manipulators, these novel actuators can be distributed over the robot body to allow greater control over its large number of degrees of freedom and to stabilize local deformations against a range of disturbances. In this paper, we present a hierarchical policy for stiffness control for such a class of soft manipulators. The stiffness changes induce desired deformations in each segment, thereby influencing the manipulator’s end-effector position. The algorithm can be run as an online controller to influence the manipulator’s stable states – as we demonstrate in simulation – or offline as a design algorithm to optimize stiffness distributions – as we showcase in a hardware demonstration. Our proposed hierarchical control scheme is agnostic to the stiffness actuation method and can extend to other soft manipulators with nonuniform stiffness distributions.},
keywords = {2024, compliant, tunable stiffness},
pubstate = {published},
tppubtype = {conference}
}
@workshop{yang2024swimmer,
title = {Bio-Inspired Approach to Energetically Efficient Jet Propulsion},
author = {Zhiyuan Yang and Cynthia Sung},
url = {https://www.colorado.edu/lab/jayaram/RoboSoft2024},
year  = {2024},
date = {2024-04-14},
urldate = {2024-04-14},
booktitle = {7th IEEE-RAS International Conference on Soft Robotics (RoboSoft) Workshop: Soft Robotics Inspired Biology},
keywords = {2024, design, swimmer, underwater},
pubstate = {published},
tppubtype = {workshop}
}
@workshop{chen2024bio,
title = {Bio-inspired quadrupedal robot with passive paws through algorithmic origami design},
author = {Wei-Hsi Chen and Xueyang Qi and Daniel Feshbach and Stanley J. Wang and Duyi Kuang and Robert Full and Daniel Koditschek and Cynthia Sung},
url = {https://www.colorado.edu/lab/jayaram/RoboSoft2024},
year  = {2024},
date = {2024-04-14},
urldate = {2024-04-14},
booktitle = {7th IEEE-RAS International Conference on Soft Robotics (RoboSoft) Workshop: Soft Robotics Inspired Biology},
howpublished = {n the workshop: Soft Robotics Inspired Biology Workshop, held in 2024 IEEE-RAS International Conference on Soft Robotics (Robosoft), San Diego, US.},
keywords = {2024, computational design, dynamic, jumping/hopping, origami},
pubstate = {published},
tppubtype = {workshop}
}
@conference{kim2024origami,
title = {Origami-Inspired Bistable Gripper with Self-Sensing Capabilities},
author = {Christopher Kim and Lele Yang and Ashwath Anbuchelvan and Raghav Garg and Niv Milbar and Flavia Vitale and Cynthia Sung},
url = {https://www.youtube.com/watch?v=7BFJBbKCvJU
https://repository.upenn.edu/entities/publication/f2892aab-8294-4e97-bd3e-3d77590c5b1e},
doi = {10.1109/RoboSoft60065.2024.10522014},
year  = {2024},
date = {2024-04-13},
urldate = {2024-04-13},
booktitle = {IEEE-RAS International Conference on Soft Robotics (Robosoft)},
abstract = {An origami-inspired bistable gripper, featuring a dual-function custom PET linear solenoid actuator that acts both as an actuator and a sensor, is presented. Movements in the permanent magnet plunger, which is directly mounted to the gripper, create induced electromotive force (emf) in the solenoid, and these induced emf measurements are used to detect snap-through actions and light contacts on the gripper. The fabrication methods for the gripper, actuator, and a gel-free soft wearable EMG electrode are outlined, and the actuator’s self-sensing method utilizing the time-integral of the induced emf measurements are explored. Because a self-sensing actuator eliminates the need for extra sensors, it allows for further miniaturization of the robot while maintaining its compactness and lightweight design. The paper also introduces a full human-in-the-loop system, allowing users to open or close the gripper with their biceps via a wearable EMG electrode. This system bridges human intent with robotic action, offering a more intuitive interaction model for robotic control.},
keywords = {2024, emf, emg, gripper, origami},
pubstate = {published},
tppubtype = {conference}
}
@conference{chen2024design,
title = {Design and Characterization of a Pneumatic Tunable-Stiffness Bellows Actuator},
author = {Rongqian Chen and Jun Kwon and Wei-Hsi Chen and Cynthia Sung},
doi = {10.1109/RoboSoft60065.2024.10521916},
year  = {2024},
date = {2024-04-13},
urldate = {2024-04-13},
booktitle = {IEEE-RAS International Conference on Soft Robotics (RoboSoft)},
abstract = {We introduce a self-contained pneumatic actuator capable of 1.43 times stiffness gain from 1332 N/m to 1913 N/m without needing an external air source or valve. The design incorporates an air chamber bellows and a spring bellows, connected and sealed. Stiffness modulation is achieved by altering the air chamber volume. We present an approach for computing the volume, pressurized force, and stiffness of a single bellows component, as well as methods for composing single bellows models to predict the change in stiffness of the dual bellows actuator as a function of air chamber compression. We detail the fabrication of the actuator and verify the models on the fabricated prototype. This actuator holds promise for future integration in tunable stiffness robots demanding high strength and adaptability in dynamic scenarios.},
keywords = {2024, tunable stiffness},
pubstate = {published},
tppubtype = {conference}
}
@conference{feshbach2023curvequad,
title = {CurveQuad: A centimeter-scale origami quadruped that leverages curved creases to self-fold and crawl with one motor},
author = {Daniel Feshbach and Xuelin Wu and Satviki Vasireddy and Louis Beardell and Bao To and Yuliy Baryshnikov and Cynthia Sung},
url = {https://www.youtube.com/watch?v=RnSHG5F2Iek&ab_channel=SungRoboticsGroup
https://sung.seas.upenn.edu/publications/curvequad/},
doi = {10.1109/IROS55552.2023.10342339},
year  = {2023},
date = {2023-10-01},
urldate = {2023-10-01},
booktitle = {IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS)},
abstract = {We present CurveQuad, a miniature curved origami quadruped that is able to self-fold and unfold, crawl, and steer, all using a single actuator. CurveQuad is designed for planar manufacturing, with parts that attach and stack sequentially on a flat body. The design uses 4 curved creases pulled by 2 pairs of tendons from opposite ends of a link on a 270deg servo. It is 8 cm in the longest direction and weighs 10.9 g. Rotating the horn pulls the tendons inwards to induce folding. Continuing to rotate the horn shears the robot, enabling the robot to shuffle forward while turning in either direction. We experimentally validate the robot’s ability to fold, steer, and unfold by changing the magnitude of horn rotation. We also demonstrate basic feedback control by steering towards a light source from a variety of starting positions and orientations, and swarm aggregation by having 4 robots simultaneously steer towards the light. The results demonstrate the potential of using curved crease origami in self-assembling and deployable robots with complex motions such as locomotion.},
keywords = {2023, origami, self-folding},
pubstate = {published},
tppubtype = {conference}
}
@inproceedings{chen2023drag,
title = {Drag coefficient characterization of the origami magic ball},
author = {Guanyu Chen and Dongsheng Chen and Jessica Weakly and Cynthia Sung},
url = {https://repository.upenn.edu/grasp_papers/73},
doi = {10.1115/DETC2023-117182},
year  = {2023},
date = {2023-08-29},
urldate = {2023-08-29},
booktitle = {ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference (IDETC/CIE)},
pages = {DETC2023-117182},
abstract = {The drag coefficient plays a vital role in the design and optimization of robots that move through fluids. From aircraft to underwater vehicles, their geometries are specially engineered so that the drag coefficients are as low as possible to achieve energy-efficient performances. Origami magic balls are 3-dimensional reconfigurable geometries composed of repeated simple waterbomb units. Their volumes can change as their geometries vary and we have used this concept in a recent underwater robot design. This paper characterizes the drag coefficient of an origami magic ball in a wind tunnel. Through dimensional analysis, the scenario where the robot swims underwater is equivalently transferred to the situation when it is in the wind tunnel. With experiments, we have collected and analyzed the drag force data. It is concluded that the drag coefficient of the magic ball increases from around 0.64 to 1.26 as it transforms from a slim ellipsoidal shape to an oblate spherical shape. Additionally, three different magic balls produce increases in the drag coefficient of between 57% and 86% on average compared to the smooth geometries of the same size and aspect ratio. The results will be useful in future designs of robots using waterbomb origami in fluidic environments.},
keywords = {2023, origami, swimmer},
pubstate = {published},
tppubtype = {inproceedings}
}
@conference{chen2023electronics,
title = {Electronics Design and Verification for Robots With Actuation and Sensing Requirements},
author = {Dongsheng Chen and Zonghao Huang and Cynthia Sung},
url = {https://repository.upenn.edu/entities/publication/20eeddb9-8163-44c4-bec4-ed47f62d8f4b},
doi = {10.1115/DETC2023-115313},
year  = {2023},
date = {2023-08-29},
urldate = {2023-08-29},
booktitle = {ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference (IDETC/CIE)},
pages = {DETC2023-115313},
abstract = {Robot design is a challenging problem involving a balance between the robot's mechanical design, kinematic structure, and actuation and sensing capabilities. Recent work in computational robot design has focused on mechanical design while assuming that the given actuators are sufficient for the task. At the same time, existing electronics design tools ignore the physical requirements of the actuators and sensors in the circuit. In this paper, we present the first system that closes the loop between the two, incorporating a robot's mechanical requirements into its circuit design process. We show that the problem can be solved using an iterative search consisting of two parts. First, a dynamic simulator converts the mechanical design and the given task into concrete actuation and sensing requirements. Second, a circuit generator executes a branch-and-bound search to convert the design requirements into a feasible electronic design. The system iterates through both of these steps, a process that is sometimes required since the electronics components add mass that may affect the robot's design requirements. We demonstrate this approach on two examples -- a manipulator and a quadruped -- showing in both cases that the system is able to generate a valid electronics design.},
keywords = {2023, computational design},
pubstate = {published},
tppubtype = {conference}
}
@conference{wilson2023impact,
title = {The Impact of Robotics Expertise on Iterative Robot Design Decisions and Vulnerability to Anchoring Bias},
author = {Cristina Wilson and Kallahan Brown and Cynthia Sung},
url = {https://youtu.be/hFHxWawZ4_w},
doi = {10.1115/DETC2023-116874},
year  = {2023},
date = {2023-08-28},
urldate = {2023-08-28},
booktitle = {ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference (IDETC/CIE)},
pages = {DETC2023-116874},
abstract = {Robot design is a complex cognitive activity that requires the designer to iteratively navigate multiple engineering disciplines and the relations between them. In this paper, we explore how people approach robot design and how trends in design strategy vary with the level of expertise of the designer. Using our interactive Build-a-Bot software tool, we recruited 39 participants from the 2022 IEEE International Conference on Robotics and Automation. These participants varied in age from 19 to 56 years, and had between 0 and 17 years of robotics experience. We tracked the participants' design decisions over the course of a 15~min. task of designing a ground robot to cross an uneven environment. Our results showed that participants engaged in iterative testing and modification of their designs, but unlike previous studies, there was no statistically significant effect of participant's expertise on the frequency of iterations. We additionally found that, across levels of expertise, participants were vulnerable to anchoring-and-adjustment, in which they latched onto an initial design concept and insufficiently adjusted the design, even when confronted with difficulties developing the concept into a satisfactory solution. 
The results raise interesting questions for how future engineers can avoid design bias and how design tools can assist in both efficient assessment and optimization of design workflow for complex design tasks.},
keywords = {2023, computational design},
pubstate = {published},
tppubtype = {conference}
}
@conference{misra2023design,
title = {Design and Control of a Tunable-Stiffness Coiled-Spring Actuator},
author = {Shivangi Misra and Mason Mitchell and Rongqian Chen and Cynthia Sung},
url = {https://repository.upenn.edu/grasp_papers/72/
https://youtu.be/52WVMEeGxUk
},
doi = {10.1109/ICRA48891.2023.10161218},
year  = {2023},
date = {2023-05-30},
urldate = {2023-05-30},
booktitle = {IEEE International Conference on Robotics and Automation (ICRA)},
abstract = {We propose a novel design for a lightweight and compact tunable stiffness actuator capable of stiffness changes up to 20x. The design is based on the concept of a coiled spring, where changes in the number of layers in the spring change the bulk stiffness in a near-linear fashion. We present an elastica nested rings model for the deformation of the proposed actuator and empirically verify that the designed stiffness-changing spring abides by this model. Using the resulting model, we design a physical prototype of the tunable-stiffness coiled spring actuator and discuss the effect of design choices on the resulting achievable stiffness range and resolution. In the future, this actuator design could be useful in a wide variety of soft robotics applications, where fast, controllable, and local stiffness change is required over a large range of stiffnesses.},
keywords = {2023, compliant, reconfiguration, tunable stiffness},
pubstate = {published},
tppubtype = {conference}
}
@workshop{chen2023DOQ,
title = {DOQ: A Dynamic Origami Quadrupedal Robot},
author = {Wei-Hsi Chen and Shane Rozen-Levy and Griffin Addison and Lucien Peach and Daniel E. Koditschek and Cynthia R. Sung},
year  = {2023},
date = {2023-05-29},
urldate = {2023-05-29},
booktitle = {ICRA Workshop on Origami-based Structures for Designing Soft Robots with New Capabilities},
keywords = {},
pubstate = {published},
tppubtype = {workshop}
}
@article{chen2022kinegami,
title = {Kinegami: Algorithmic Design of Compliant Kinematic Chains From Tubular Origami},
author = {Wei-Hsi Chen and Woohyeok Yang and Lucien Peach and Daniel E. Koditschek and Cynthia R. Sung},
url = {https://repository.upenn.edu/ese_papers/884/
https://www.youtube.com/watch?v=IT58JeMoAr0
https://github.com/weinitor/Kinegami},
doi = {10.1109/TRO.2022.3206711},
year  = {2023},
date = {2023-04-01},
urldate = {2023-04-01},
journal = {IEEE Transactions on Robotics},
volume = {39},
issue = {2},
pages = {1260-1280},
abstract = {Origami processes can generate both rigid and compliant structures from the same homogeneous sheet material. In this article, we advance the origami robotics literature by showing that it is possible to construct an arbitrary rigid kinematic chain with prescribed joint compliance from a single tubular sheet. Our “Kinegami” algorithm converts a Denavit–Hartenberg specification into a single-sheet crease pattern for an equivalent serial robot mechanism by composing origami modules from a catalogue. The algorithm arises from the key observation that tubular origami linkage design reduces to a Dubins path planning problem. The automatically generated structural connections and movable joints that realize the specified design can also be endowed with independent user-specified compliance. We apply the Kinegami algorithm to a number of common robot mechanisms and hand-fold their algorithmically generated single-sheet crease patterns into functioning kinematic chains. We believe this is the first completely automated end-to-end system for converting an abstract manipulator specification into a physically realizable origami design that requires no additional human input.},
note = {Honorable mention for 2023 IEEE Transactions on Robotics King-Sun Fu Memorial Best Paper Award},
keywords = {2023, computational design, origami},
pubstate = {published},
tppubtype = {article}
}
@conference{huang2022evorobogami,
title = {EvoRobogami: Co-designing with Humans in Evolutionary Robotics Experiments},
author = {Zonghao Huang and Quinn Wu and David Howard and Cynthia Sung},
url = {https://arxiv.org/abs/2205.08086
https://sung.seas.upenn.edu/publications/evorobogami-gecco-2022/},
doi = {10.1145/3512290.3528867},
year  = {2022},
date = {2022-07-09},
urldate = {2022-07-09},
booktitle = {Genetic and Evolutionary Computation Conference (GECCO)},
abstract = {We study the effects of injecting human-generated designs into the initial population of an evolutionary robotics experiment, where subsequent population of robots are optimised via a Genetic Algorithm and MAP-Elites. First, human participants interact via a graphical front-end to explore a directly-parameterised legged robot design space and attempt to produce robots via a combination of intuition and trial-and-error that perform well in a range of environments. Environments are generated whose corresponding high-performance robot designs range from intuitive to complex and hard to grasp. Once the human designs have been collected, their impact on the evolutionary process is assessed by replacing a varying number of designs in the initial population with human designs and subsequently running the evolutionary algorithm. Our results suggest that a balance of random and hand-designed initial solutions provides the best performance for the problems considered, and that human designs are most valuable when the problem is intuitive. The influence of human design in an evolutionary algorithm is a highly understudied area, and the insights in this paper may be valuable to the area of AI-based design more generally. },
keywords = {2022, computational design},
pubstate = {published},
tppubtype = {conference}
}
@article{liu2022increasing,
title = {Increasing Reliability of Self-Folding of the Origami Hypar},
author = {Addison Liu and Mykell Johnson and Cynthia Sung},
doi = {10.1115/1.4054310},
year  = {2022},
date = {2022-06-01},
urldate = {2022-06-01},
journal = {ASME Journal of Mechanisms and Robotics},
volume = {14},
number = {6},
pages = {061003},
abstract = {Self-folding systems, which can transform autonomously from a flat sheet into a 3D machine, provide opportunities for rapidly fabricable robots that are deployable on-demand. Existing self-folding fabrication processes convert fold patterns into laminated structures that respond to external stimuli, most commonly heat. However, demonstrations of these approaches have been generally limited to simple fold patterns with little ambiguity in folding configuration, and the reliability of self-folding drops drastically with the fold pattern complexity. In this paper, we explore methods of biasing a symmetric fold pattern, the origami hyperbolic paraboloid (hypar), to fold into one of two possible configurations. The biasing methods are simulated using a bar-and-hinge inspired self-folding model that defines a single fold as a bending beam and the hypar crease pattern as an elastic spring network. Simulation results are also verified on physical samples. Based on these results, three techniques to bias the hypar by manipulating the target fold angles are proposed and tested. The results show that biasing a self-folding pattern can increase folding accuracy from 50% (purely random) to 70%, and provide insights for improving the reliability of future self-folding systems with complex fold patterns.},
keywords = {2022, origami, self-folding},
pubstate = {published},
tppubtype = {article}
}
@conference{misra2022forward,
title = {Forward kinematics and control of a segmented tunable-stiffness 3-D continuum manipulator},
author = {Shivangi Misra and Cynthia Sung},
url = {https://repository.upenn.edu/grasp_papers/69/
https://youtu.be/P-vg3Hiuk4M
https://youtu.be/lc6W61xCWuQ},
doi = {10.1109/ICRA46639.2022.9812098},
year  = {2022},
date = {2022-05-23},
urldate = {2022-05-23},
booktitle = {IEEE International Conference on Robotics and Automation (ICRA)},
abstract = {In this work, we consider the problem of controlling the end effector position of a continuum manipulator through local stiffness changes. Continuum manipulators offer the advantage of continuous deformation along their lengths, and recent advances in smart material actuators further enable local compliance changes, which can affect the manipulator's bulk motion. However, leveraging local stiffness change to control motion remains lightly explored. We build a kinematic model of a continuum manipulator as a sequence of segments consisting of symmetrically arranged springs around the perimeter of every segment, and we show that this system has a closed form solution to its forward kinematics. The model includes common constraints such as restriction of torsional or shearing movement. Based on this model, we propose a controller on the spring stiffnesses for a single segment and provide provable guarantees on convergence to a desired goal position. The results are verified in simulation and compared to physical hardware.},
keywords = {2022, compliant, tunable stiffness},
pubstate = {published},
tppubtype = {conference}
}
@conference{sun2022repeated,
title = {Repeated jumping with the REBOund: Self-righting jumping robot leveraging bistable origami-inspired design},
author = {Yuchen Sun* and Joanna Wang* and Cynthia Sung},
url = {https://repository.upenn.edu/grasp_papers/70/
https://youtu.be/LoCXcwIxCgU
https://youtu.be/JXWAp-rVOxg},
doi = {10.1109/ICRA46639.2022.9812232},
year  = {2022},
date = {2022-05-23},
urldate = {2022-05-23},
booktitle = {IEEE International Conference on Robotics and Automation (ICRA)},
abstract = {Repeated jumping is crucial to the mobility of jumping robots. In this paper, we extend upon the REBOund jumping robot design, an origami-inspired jumping robot that uses the Reconfigurable Expanding Bistable Origami (REBO) pattern as its body. The robot design takes advantage of the pattern's bistability to jump with controllable timing. For jump repeatedly, we also add self-righting legs that utilize a single motor actuation mechanism. We describe a dynamic model that captures the compression of the REBO pattern and the REBOund self-righting process and compared it to the physical robot. Our experiments show that the REBOund is able to successfully self-right and jump repeatedly over tens of jumps.},
note = {* = co-first author},
keywords = {2022, jumping/hopping, origami},
pubstate = {published},
tppubtype = {conference}
}
@conference{qin2022trussbot,
title = {TrussBot: Modeling, design and control of a compliant, helical truss of tetrahedral modules},
author = {Yuhong Qin* and Linda Ting* and Celestina Saven* and Yumika Amemiya and Michael Tanis and Randall Kamien and Cynthia Sung},
url = {https://repository.upenn.edu/grasp_papers/71/
https://youtu.be/bcvFMq40EzI
https://youtu.be/mGf1qmQVNmg},
doi = {10.1109/ICRA46639.2022.9812295},
year  = {2022},
date = {2022-05-23},
urldate = {2022-05-23},
booktitle = {IEEE International Conference on Robotics and Automation},
abstract = {Modular and truss robots offer the potential of high reconfigurability and great functional flexibility, but common implementations relying on rigid components often lead to highly complex actuation and control requirements. This paper introduces a new type of modular, compliant robot: TrussBot. TrussBot is composed of 3D-printed tetrahedral modules connected at the corners with compliant joints. We propose a truss geometry, analyze its deformation modes, and provide a simulation framework for predicting its behavior under applied loads and actuation. The TrussBot is geometrically constrained, thus requiring compliant joints to move. The TrussBot can be actuated through a network of tendons which pinch vertices together and apply a twisting motion due to the structure's connectivity. The truss was demonstrated in a physical prototype and compared to simulation results. },
note = {*=co-first author},
keywords = {2022, compliant, reconfiguration},
pubstate = {published},
tppubtype = {conference}
}
@workshop{misra2022control,
title = {Control of a segmented tunable-stiffness 3-D continuum manipulator},
author = {Shivangi Misra and Cynthia Sung},
year  = {2022},
date = {2022-05-23},
urldate = {2022-05-23},
booktitle = {ICRA Workshop on Compliant Robot Manipulation: Challenges and New Opportunities},
keywords = {2022, compliant, reconfiguration, tunable stiffness},
pubstate = {published},
tppubtype = {workshop}
}
@article{lee2021tendon,
title = {Tendon-Driven Auxetic Tubular Springs for Resilient Hopping Robots},
author = {Young-Joo Lee and Shivangi Misra and Wei-Hsi Chen and Daniel E. Koditschek and Cynthia Sung and Shu Yang},
doi = {10.1002/aisy.202100152},
year  = {2021},
date = {2021-12-19},
urldate = {2021-12-19},
journal = {Advanced Intelligent Systems},
volume = {4},
pages = {2100152},
abstract = {Compliance in jumping robots improves gait stability and enables energy-efficient locomotion. Here, 3D printable auxetic tubular springs from thermoplastic polyurethane (TPU) for rapid and sustainable hopping are developed. Because the springs have negative Poisson's ratios, they become stiffer as compression proceeds and theoretically stores 35.2% more energy than a linear spring with the same stiffness. As the stress concentrates on the hinges, it is revealed through experimental, numerical, and analytical investigations that hinge geometries, for example, the lattice angle and hinge radius, governs the global stiffness and robustness of the springs. The hopping robot leg composed of three auxetic tubular springs in parallel sustains more than 1,000 cycles of repeated, one-degree-of-freedom (1-DOF) vertical hopping and two-degree-of-freedom (2-DOF) forward hopping. The 2.5 kg-robot system requires minimum 420 mJ of elastic energy for repeated hopping. The springs are pre-compressed by tendon-driven actuators and stores 1.08 J during jumping and release the springs when touching the ground. The power stroke is calculated as 15–18 W. The average velocity of the hopping robot reaches 0.06 m s−1 with the increase of touchdown angle to 0.125 rad. The cost of transport is calculated as 6.7, similar to those of the living organisms.},
keywords = {2021, auxetic, compliant, jumping/hopping},
pubstate = {published},
tppubtype = {article}
}
@conference{yuan2021programmable,
title = {Programmable Stiffness and Applications of 3D Printed TPU Diamond Lattices},
author = {Yifan Yuan and Cynthia Sung},
doi = {10.1115/DETC2021-69826},
year  = {2021},
date = {2021-11-17},
urldate = {2021-11-17},
booktitle = {International Design Engineering Technical Conferences & Computers and Information in Engineering Conference},
number = {DETC2021-69826, V08AT08A016},
abstract = {Additive manufacturing provides a rapid manufacturing method for a variety of materials with different applications. Thermoplastic Polyurethane (TPU) is a soft polymer material that can be 3D printed. In this work, we explore the mechanical properties of a 3D printed grid pattern structure with TPU. By changing the pattern's cell size and wall thickness parameters, we control the density of the grid lattice and, as a result, the bulk elastic modulus of the structure. We compare simulation and physical compression tests and conclude that the bulk elastic modulus of a print is related to the infill percentage according to a cubic relationship, with higher infill percentage samples resulting in higher elastic moduli. The precise cell size and wall thickness parameter values are minor influences comparatively. The elastic moduli of the resulting samples span from 0.36 MPa with 23.44% infill to 21.83 MPa with 75% infill, compared to an elastic modulus of 64.31 MPa when printing at 100% density. We also explore other factors such as the sample size, the printer, the build orientation, and the sample geometry. The results have uses in a variety of applications, including a custom linear spring, a bistable gripper, or a soft robot finger. },
keywords = {2021, compliant, design},
pubstate = {published},
tppubtype = {conference}
}
@article{yang2021origami,
title = {Origami-inspired robot that swims via jet propulsion},
author = {Zhiyuan Yang and Dongsheng Chen and David J. Levine and Cynthia Sung},
url = {https://repository.upenn.edu/grasp_papers/68
https://youtu.be/cZ1nx_kOw3w},
doi = {10.1109/LRA.2021.3097757},
year  = {2021},
date = {2021-07-19},
urldate = {2021-07-19},
booktitle = {IEEE Robotics and Automation Letters},
journal = {IEEE Robotics and Automation Letters},
volume = {6},
number = {4},
pages = {7145-7152},
abstract = {Underwater swimmers present unique opportunities for using bodily reconfiguration for self propulsion. Origami-inspired designs are low-cost, fast to fabricate, robust, and can be used to create compliant mechanisms useful in energy efficient underwater locomotion. In this paper, we demonstrate an origami-inspired robot that can change its body shape to ingest and expel water, creating a jet that propels it forward similarly to cephalopods. We use the magic ball origami pattern, which can transform between ellipsoidal (low volume) and spherical (high volume) shapes. A custom actuation mechanism contracts the robot to take in fluid, and the inherent mechanics of the magic ball returns the robot to its natural shape upon release. We describe the design and control of this robot and verify its locomotion in a water tank. The resulting robot is able to move forward at 6.7 cm/s (0.2 body lengths/s), with a cost of transport of 2.0. },
keywords = {2021, design, origami, underwater},
pubstate = {published},
tppubtype = {article}
}
@article{feshbach2021reconfiguring,
title = {Reconfiguring Non-Convex Holes in Pivoting Modular Cube Robots},
author = {Daniel Feshbach and Cynthia Sung},
url = {https://repository.upenn.edu/cis_papers/865/
https://www.youtube.com/watch?v=IoyFs_K5RNE
https://github.com/SungRoboticsGroup/PIVOTING-CUBES_cube-reconfiguration},
doi = {10.1109/LRA.2021.3095030},
year  = {2021},
date = {2021-07-07},
urldate = {2021-07-07},
journal = {IEEE Robotics and Automation Letters},
volume = {6},
number = {4},
pages = {6701-6708},
abstract = {We present an algorithm for self-reconfiguration of admissible 3D configurations of pivoting modular cube robots with holes of arbitrary shape and number. Cube modules move across the surface of configurations by pivoting about shared edges, enabling configurations to reshape themselves. Previous work provides a reconfiguration algorithm for admissible 3D configurations containing no non-convex holes; we improve upon this by handling arbitrary admissible 3D configurations. The key insight specifies a point in the deconstruction of layers enclosing non-convex holes at which we can pause and move inner modules out of the hole. We prove this happens early enough to maintain connectivity, but late enough to open enough room in the enclosing layer for modules to escape the hole. Our algorithm gives reconfiguration plans with O(n^2) moves for n modules.},
keywords = {2021, reconfiguration},
pubstate = {published},
tppubtype = {article}
}
@article{cha2021carbon,
title = {Carbon fiber–aluminum sandwich for micro-aerial vehicles and miniature robots},
author = {Wujoon Cha and Luke Kaspar and Matthew F. Campbell and Thomas J. Calenza and George A. Popov and Jeremy Wang and Cynthia R. Sung and Mark Yim and Igor Bargatin},
doi = {10.1557/s43580-021-00084-3},
year  = {2021},
date = {2021-06-16},
urldate = {2021-06-16},
journal = {MRS Advances},
volume = {6},
pages = {477–481},
abstract = {We present carbon-fiber and aluminum sandwich plates with millimeter thicknesses that exhibit high stiffness- and strength-to-weight ratios. These composites consist of carbon-fiber-reinforced polymer faces and waterjet-cut aluminum cores, bonded using epoxy. Relative to single-ply carbon-fiber-reinforced polymer sheets, this construction provides 22-fold increases in mass-specific flexural rigidity and 18-fold increases in mass-specific flexural strength, with areal densities of only 120–260 mg/cm2. Our work represents a simple and inexpensive platform for creating extremely lightweight structural components for microflyers and small robots.},
keywords = {2021, aerial},
pubstate = {published},
tppubtype = {article}
}
@conference{li2021hav,
title = {Soft hybrid aerial vehicle via bistable mechanism},
author = {Xuan Li* and Jessica McWilliams* and Minchen Li and Cynthia Sung and Chenfanfu Jiang},
url = {https://arxiv.org/abs/2011.00426
https://www.youtube.com/watch?v=fnTyAVVzJMc},
doi = {10.1109/ICRA48506.2021.9561434},
year  = {2021},
date = {2021-05-01},
urldate = {2021-05-01},
booktitle = {IEEE International Conference on Robotics and Automation (ICRA)},
abstract = {Unmanned aerial vehicles have been demonstrated successfully in a variety of tasks, including surveying and sampling tasks over large areas. These vehicles can take many forms. Quadrotors' agility and ability to hover makes them well suited for navigating potentially tight spaces, while fixed wing aircraft are capable of efficient flight over long distances. Hybrid aerial vehicles (HAVs) attempt to achieve both of these benefits by exhibiting multiple modes; however, morphing HAVs typically require extra actuators which add mass, reducing both agility and efficiency. We propose a morphing HAV with folding wings that exhibits both a quadrotor and a fixed wing mode without requiring any extra actuation. This is achieved by leveraging the motion of a bistable mechanism at the center of the aircraft to drive folding of the wing using only the existing motors and the inertia of the system. We optimize both the bistable mechanism and the folding wing using a topology optimization approach. The resulting mechanisms were fabricated on a 3D printer and replaced the frame of an existing quadrotor. Our prototype successfully transitions between both modes and our experiments demonstrate that the behavior of the fabricated prototype is consistent with that of the simulation.},
note = {*=co-first author, best paper in mechanisms and design},
keywords = {2021, compliant, computational design},
pubstate = {published},
tppubtype = {conference}
}
@conference{mcwilliams2021push,
title = {Push On, Push Off: A compliant bistable gripper with mechanical sensing and actuation},
author = {Jessica McWilliams and Yifan Yuan and Jason Friedman and Cynthia Sung},
url = {https://www.youtube.com/watch?v=z50dYYzYvls
https://repository.upenn.edu/meam_papers/307/},
doi = {10.1109/RoboSoft51838.2021.9479209},
year  = {2021},
date = {2021-04-01},
urldate = {2021-04-01},
booktitle = {IEEE International Conference on Soft Robotics (RoboSoft)},
pages = {622-629},
abstract = {Grasping is an essential task in robotic applications and is an open challenge due to the complexity and uncertainty of contact interactions. In order to achieve robust grasping, systems typically rely on precise actuators and reliable sensing in order to control the contact state. We propose an alternative design paradigm that leverages contact and a compliant bistable mechanism in order to achieve "sensing" and "actuation" purely mechanically. To grasp an object, the manipulator holding our end effector presses the bistable mechanism into the object until snap-through causes the gripper to enclose it. To release the object, the tips of the gripper are pushed against the ground, until rotation of the linkages causes snap-through in the other direction. This push-on push-off scheme reduces the complexity of the grasping task by allowing the manipulator to automatically achieve the correct grasping behavior as long as it can get the end effector to the correct location and apply sufficient force. We present our dynamic model for the bistable gripping mechanism, propose an optimized result, and demonstrate the functionality of the concept on a fabricated prototype. We discuss our stiffness tuning strategy for the 3D printed springs, and verify the snap-through behavior of the system using compression tests on an MTS machine. },
keywords = {2021, compliant, computational design},
pubstate = {published},
tppubtype = {conference}
}
@conference{kim2021sma,
title = {Fabrication and characterization of I-cord knitted SMA actuators},
author = {Christopher Kim and Athena Chien and Megha Tippur and Cynthia Sung},
url = {https://www.youtube.com/watch?v=Czoy5NctBtY
https://repository.upenn.edu/meam_papers/308/
},
doi = {10.1109/RoboSoft51838.2021.9479207},
year  = {2021},
date = {2021-04-01},
urldate = {2021-04-01},
booktitle = {IEEE International Conference on Soft Robotics (RoboSoft)},
pages = {379-386},
abstract = {Knitted SMA actuators provide greater actuation stroke than single-strand SMA wire actuators by leveraging its knitted structure. However, due to short-circuiting through interlacing knit loops, existing knitted SMA sheet actuators are unsuitable for joule-heating actuation when uniform contractile actuation is desired. We explore an axially symmetric tubular i-cord knitted actuator as a possible solution. The fabrication process of an i-cord knitted SMA actuator and its electrical, thermal, and mechanics models are presented. After modifying existing models for single-strand SMA wire and adjusting their parameters, the proposed electrical, thermal, and mechanics models were verified with experimental results.},
keywords = {2021, actuation, compliant},
pubstate = {published},
tppubtype = {conference}
}
@article{cha2020microfabricated,
title = {Microfabricated foldable wings for centimeter-scale microflyers},
author = {Wujoon Cha and Matthew F. Campbell and George A. Popov and Christopher H. Stanczak and Anna K. Estep and Edward B. Steager and Cynthia R. Sung and Mark H. Yim and Igor Bargatin},
doi = {10.1109/JMEMS.2020.3013813},
year  = {2020},
date = {2020-10-01},
urldate = {2020-10-01},
journal = {Journal of Microelectromechanical Systems},
volume = {29},
number = {5},
pages = {1127-1129},
abstract = {Many micro-aerial vehicles can benefit from having compact and robust pre-deployment configurations that can later transform into larger and more capable forms. We demonstrate parylene-covered silicon frames that can be folded into origami-inspired aerodynamic shapes for structural applications in centimeter-scale aircraft. By changing the spacing between the frames, we can control the conformality of the parylene deposition, which determines the directionality of the fold (mountain or valley). We fabricated a foldable propeller from such polymer-coated frames and characterized its mass and thrust.},
keywords = {2020, aerial},
pubstate = {published},
tppubtype = {article}
}
@conference{carlson2020rebound,
title = {REBOund: Untethered origami jumping robot with controllable jump height},
author = {Jaimie Carlson and Jason Friedman and Christopher Kim and Cynthia Sung},
url = {https://sung.seas.upenn.edu/wp-content/publications/carlsonICRA2020_jumper.pdf},
doi = {10.1109/ICRA40945.2020.9196534},
year  = {2020},
date = {2020-06-01},
urldate = {2020-06-01},
booktitle = {IEEE International Conference on Robotics and Automation (ICRA)},
pages = {10089-10095},
abstract = {Origami robots are well-suited for jumping maneuvers because of their light weight and ability to incorporate actuation and control strategies directly into the robot body. However, existing origami robots often model fold patterns as rigidly foldable and fail to take advantage of deformation in an origami sheet for potential energy storage. In this paper, we consider a parametric origami tessellation, the Reconfigurable Expanding Bistable Origami (REBO) pattern, which leverages face deformations to act as a nonlinear spring. We present a pseudo-rigid-body model for the REBO for computing its energy stored when compressed to a given displacement and compare that model to experimental measurements taken on a mechanical testing system. This stored potential energy, when released quickly, can cause the pattern to jump. Using our model and experimental data, we design and fabricate a jumping robot, REBOund, that uses the spring-like REBO pattern as its body. Four lightweight servo motors with custom release mechanisms allow for quick compression and release of the origami pattern, allowing the fold pattern to jump over its own height even when carrying 5 times its own weight in electronics and power. We further demonstrate that small geometric changes to the pattern allow us to change the jump height without changing the actuation or control mechanism.},
keywords = {2020, compliant, jumping/hopping, origami},
pubstate = {published},
tppubtype = {conference}
}
@conference{chen2020tendon,
title = {A tendon-driven origami hopper triggered by proprioceptive contact detection},
author = {Wei-Hsi Chen and Shivangi Misra and J. Diego Caporale and Daniel E. Koditschek and Shu Yang and Cynthia Sung},
url = {https://repository.upenn.edu/ese_papers/866/
https://youtu.be/3fx-vVZki5c},
doi = {10.1109/RoboSoft48309.2020.9116040},
year  = {2020},
date = {2020-05-26},
urldate = {2020-05-26},
booktitle = {IEEE International Conference on Soft Robotics (RoboSoft)},
abstract = {We report on experiments with a laptop-sized (0.23m, 2.53kg), paper origami robot that exhibits highly dynamic and stable two degree-of-freedom (circular boom) hopping at speeds in excess of 1.5 bl/s (body-lengths per second) at a specific resistance O(1) while achieving aerial phase apex states 25% above the stance height over thousands of cycles. Three conventional brushless DC motors load energy into the folded paper springs through pulley-borne cables whose sudden loss of tension upon touchdown triggers the release of spring potential that accelerates the body back through liftoff to flight with a 20W powerstroke, whereupon the toe angle is adjusted to regulate fore-aft speed. We also demonstrate in the vertical hopping mode the transparency of this actuation scheme by using proprioceptive contact detection with only motor encoder sensing. The combination of actuation and sensing shows potential to lower system complexity for tendon-driven robots.},
keywords = {2020, compliant, dynamic, jumping/hopping, origami},
pubstate = {published},
tppubtype = {conference}
}
@article{chen2020programmably,
title = {A programmably compliant origami mechanism for dynamically dexterous robots},
author = {Wei-Hsi Chen and Shivangi Misra and Yuchong Gao and Young-Joo Lee and Daniel E. Koditschek and Shu Yang and Cynthia Sung},
url = {https://repository.upenn.edu/ese_papers/863/
https://youtu.be/baYOFxw-5T8},
doi = {10.1109/LRA.2020.2970637},
year  = {2020},
date = {2020-01-31},
urldate = {2020-01-31},
journal = {IEEE Robotics and Automation Letters},
volume = {5},
number = {2},
pages = {2131-2137},
abstract = {We present an approach to overcoming challenges in dynamical dexterity for robots through programmably compliant origami mechanisms. Our work leverages a one-parameter family of flat sheet crease patterns that folds into origami bellows, whose axial compliance can be tuned to select desired stiffness. Concentrically arranged cylinder pairs reliably manifest additive stiffness, extending the programmable range by nearly an order of magnitude and achieving bulk axial stiffness spanning 200-1500 Nm^{-1} using 8 mil thick polyester-coated paper. Accordingly, we design origami energy-storing springs with a stiffness of 1035 Nm^{-1} each and incorporate them into a three degree-of-freedom (DOF) tendon-driven spatial pointing mechanism that exhibits trajectory tracking accuracy less than 15% rms error within a (~2 cm)^{3} volume. The origami springs can sustain high power throughput, enabling the robot to achieve asymptotically stable juggling for both highly elastic (1 kg resilient shotput ball) and highly damped (“medicine ball”) collisions in the vertical direction with apex heights approaching 10 cm. The results demonstrate that “soft” robotic mechanisms are able to perform a controlled, dynamically actuated task.},
keywords = {2020, compliant, dynamic, jumping/hopping, origami},
pubstate = {published},
tppubtype = {article}
}
@article{tosun2019optimal,
title = {Optimal Structure Synthesis for Environment Augmenting Robots},
author = { Tarik Tosun and Cynthia Sung and Colin McCloskey and Mark Yim },
doi = {10.1109/LRA.2019.2893879},
year  = {2019},
date = {2019-04-01},
urldate = {2019-04-01},
journal = {IEEE Robotics and Automation Letters},
volume = {4},
number = {2},
pages = {1069-1076},
abstract = {Building structures can allow a robot to surmount large obstacles, expanding the set of areas it can reach. This paper presents a planning algorithm to automatically determine what structures a construction-capable robot must build in order to traverse its entire environment. Given an environment, a set of building blocks, and a robot capable of building structures, we seek a optimal set of structures (using a minimum number of building blocks) that could be built to make the entire environment traversable with respect to the robot's movement capabilities. We show that this problem is NP-Hard, and present a complete, optimal algorithm that solves it using a branch-and-bound strategy. The algorithm runs in exponential time in the worst case, but solves typical problems with practical speed. In hardware experiments, we show that the algorithm solves 3D maps of real indoor environments in about one minute, and that the structures selected by the algorithm allow a robot to traverse the entire environment. An accompanying video is available online at https://youtu.be/B9WM557NP44.},
keywords = {2019, reconfiguration},
pubstate = {published},
tppubtype = {article}
}
@conference{yuan2018programmable,
title = {Programmable 3-D surfaces using origami tessellations},
author = {Hang Yuan and James Pikul and Cynthia Sung},
url = {https://sung.seas.upenn.edu/wp-content/publications/yuan_7OSME_2018_programmable.pdf},
year  = {2018},
date = {2018-09-19},
urldate = {2018-09-19},
booktitle = {7th International Meeting on Origami in Science, Mathematics, and Education},
pages = {893-906},
abstract = {We present an origami-inspired approach to reconfigurable surfaces. A circular origami tessellation with the ability to extend and flatten was designed to approximate radially symmetric 3-D surfaces. The pattern exhibits snap-through effects, allowing desired 3-D shapes to be maintained indefinitely without additional infrastructure or energy input. We characterize the geometry of the fold pattern and its resulting 3-D shape, present a strategy for reconfiguration, and demonstrate this strategy for surfaces with positive, negative, and zero Gaussian curvature.},
keywords = {2018, origami, reconfiguration},
pubstate = {published},
tppubtype = {conference}
}
@conference{deng2018leveraging,
title = {Leveraging compliance in origami robot legs for robust and natural locomotion},
author = {Xiang Deng and Cynthia Sung},
url = {https://sung.seas.upenn.edu/wp-content/publications/deng_7OSME_2018_leveraging.pdf},
year  = {2018},
date = {2018-09-12},
urldate = {2018-09-12},
booktitle = {7th International Meeting on Origami in Science, Mathematics, and Education},
pages = {965-980},
abstract = {We present an origami-inspired compliant robot leg design with three degree of freedom compliance. Using the proposed leg, we created a full quadrupedal robot that can walk robustly with adaption to non-flat terrains and external perturbations. We can reconfigure the design to change the stiffness. According to systematic locomotion tests, we demonstrate unique advantages of the proposed leg design over a rigid counterpart of the same dimension and weight in terms of enhancing locomotion stability},
keywords = {2018},
pubstate = {published},
tppubtype = {conference}
}
@article{yim2018animatronic,
title = {Animatronic soft robots by additive folding},
author = {Sehyuk Yim and Cynthia Sung and Shuhei Miyashita and Daniela Rus and Sangbae Kim},
doi = {10.1177/0278364918772023},
year  = {2018},
date = {2018-06-05},
urldate = {2018-06-05},
journal = {International Journal of Robotics Research},
volume = {37},
number = {6},
pages = {611-628},
abstract = {This paper presents a new class of animatronic soft robots created by a desktop fabrication mechanism called additive folding. In this method, two-dimensional (2D) slices are threaded by multiple strings, accordion-folded by flexure hinges and finally stacked into a predefined three-dimensional (3D) structure. As the 3D assembly of the slices is controlled by embedded strings, it becomes an animatronic soft robot that moves like a biological creature and that shows life-like movements. We create a computational design algorithm that takes as input a desired 3D geometry of the robot, and that produces a 2D surface with built-in folds and string-based actuators. This paper describes the entire robot design process and demonstrates various animatronic motions, highlighting the vision of desktop fabrication technology and its potential applications in animatronics and robotic art.},
keywords = {2018, computational design, origami},
pubstate = {published},
tppubtype = {article}
}
@article{rus2018spotlight,
title = {Spotlight on origami robots},
author = {Daniela Rus and Cynthia Sung},
doi = {10.1126/scirobotics.aat0938},
year  = {2018},
date = {2018-02-28},
urldate = {2018-02-28},
journal = {Science Robotics},
volume = {3},
number = {15},
pages = {eaat0938},
abstract = {Origami robots promise a future with increased customizability and adaptability in autonomous machines.},
keywords = {2018, origami},
pubstate = {published},
tppubtype = {article}
}
@article{schulz2017interactive,
title = {Interactive Robogami: An end-to-end system for design of robots with ground locomotion},
author = {Adriana Schulz and Cynthia Sung and Andrew Spielberg and Wei Zhao and Yu Cheng and Eitan Grinspun and Daniela Rus and Wojciech Matusik},
doi = {10.1177/0278364917723465},
year  = {2017},
date = {2017-08-13},
urldate = {2017-08-13},
journal = {International Journal of Robotics Research},
volume = {36},
number = {10},
pages = {1131-1147},
abstract = {This paper aims to democratize the design and fabrication of robots, enabling people of all skill levels to make robots without needing expert domain knowledge. Existing work in computational design and rapid fabrication has explored this question of customization for physical objects but so far has not been able to conquer the complexity of robot designs. We have developed Interactive Robogami, a tool for composition-based design of ground robots that can be fabricated as flat sheets and then folded into 3D structures. This rapid prototyping process enables users to create lightweight, affordable, and materially versatile robots with short turnaround time. Using Interactive Robogami, designers can compose new robot designs from a database of print-and-fold parts. The designs are tested for the users’ functional specifications via simulation and fabricated on user satisfaction. We present six robots designed and fabricated using a 3D printing based approach, as well as a larger robot cut from sheet metal. We have also conducted a user study that demonstrates that our tool is intuitive for novice designers and expressive enough to create a wide variety of ground robot designs.},
keywords = {2017, computational design},
pubstate = {published},
tppubtype = {article}
}
@conference{sung2017self,
title = {Self-folded soft robotic structures with controllable joints},
author = {Cynthia Sung and Rhea Lin and Shuhei Miyashita and Sehyuk Yim and Sangbae Kim and Daniela Rus},
doi = {10.1109/ICRA.2017.7989072},
year  = {2017},
date = {2017-05-29},
urldate = {2017-05-29},
booktitle = {IEEE International Conference on Robotics and Automation (ICRA)},
pages = {580-587},
abstract = {This paper describes additive self-folding, an origami-inspired rapid fabrication approach for creating actuatable compliant structures. Recent work in 3-D printing and other rapid fabrication processes have mostly focused on rigid objects or objects that can achieve small deformations. In contrast, soft robots often require elastic materials and large amounts of movement. Additive self-folding is a process that involves cutting slices of a 3-D object in a long strip and then pleat folding them into a likeness of the original model. The zigzag pattern for folding enables large bending movements that can be actuated and controlled. Gaps between slices in the folded model can be designed to provide larger deformations or higher shape accuracy. We advance existing planar fabrication and self-folding techniques to automate the fabrication process, enabling highly compliant structures with complex 3-D geometries to be designed and fabricated within a few hours. We describe this process in this paper and provide algorithms for converting 3-D meshes into additive self-folding designs. The designs can be rapidly instrumented for global control using magnetic fields or tendon-driven for local bending. We also describe how the resulting structures can be modeled and their responses to tendon-driven control predicted. We test our design and fabrication methods on three models (a bunny, a tuna fish, and a starfish) and demonstrate the method's potential for actuation by actuating the tuna fish and starfish models using tendons and magnetic control.},
keywords = {2017},
pubstate = {published},
tppubtype = {conference}
}
@conference{spielberg2017functional,
title = {Functional co-optimization of articulated robots},
author = {Andrew Spielberg and Brandon Araki and Cynthia Sung and Russ Tedrake and Daniela Rus},
doi = {10.1109/ICRA.2017.7989587},
year  = {2017},
date = {2017-05-29},
urldate = {2017-05-29},
booktitle = {IEEE International Conference on Robotics and Automation (ICRA)},
pages = {5035-5042},
abstract = {We present parametric trajectory optimization, a method for simultaneously computing physical parameters, actuation requirements, and robot motions for more efficient robot designs. In this scheme, robot dimensions, masses, and other physical parameters are solved for concurrently with traditional motion planning variables, including dynamically consistent robot states, actuation inputs, and contact forces. Our method requires minimal user domain knowledge, requiring only a coarse guess of the target robot configuration sequence and a parameterized robot topology as input. We demonstrate our results on four simulated robots, one of which we physically fabricated in order to demonstrate physical consistency. We demonstrate that by optimizing robot body parameters alongside robot trajectories, motion planning problems which would otherwise be infeasible can be made feasible, and actuation requirements can be significantly reduced.},
keywords = {2017, computational design},
pubstate = {published},
tppubtype = {conference}
}
@article{feldman2015idiary,
title = {iDiary: From GPS signals to a text-searchable diary},
author = {Dan Feldman and Cynthia Sung and Andrew Sugaya and Daniela Rus},
doi = {10.1145/2814569},
year  = {2015},
date = {2015-12-01},
journal = {ACM Transactions on Sensor Networks},
volume = {11},
number = {4},
pages = {60},
abstract = {This article describes iDiary, a system that takes as input GPS data streams generated by users’ phones and turns them into textual descriptions of the trajectories. The system features a user interface similar to Google Search that allows users to type text queries on their activities (e.g., “Where did I buy books?”) and receive textual answers based on their GPS signals. iDiary uses novel algorithms for semantic compression and trajectory clustering of massive GPS signals in parallel to compute the critical locations of a user. We encode these problems as follows. The k-segment mean is a k-piecewise linear function that minimizes the regression distance to the signal. The (k,m)-segment mean has an additional constraint that the projection of the k segments on Rd consists of only m ≤ k segments. A coreset for this problem is a smart compression of the input signal that allows computation of a (1+ϵ)-approximation to its k-segment or (k,m)-segment mean in O(nlogn) time for arbitrary constants ϵ, k, and m. We use coresets to obtain a parallel algorithm that scans the signal in one pass, using space and update time per point that is polynomial in log n. Using an external database, we then map these locations to textual descriptions and activities so that we can apply text mining techniques on the resulting data (e.g., LSA or transportation mode recognition). We provide experimental results for both the system and algorithms and compare them to existing commercial and academic state of the art. This is the first GPS system that enables text-searchable activities from GPS data.},
keywords = {2015},
pubstate = {published},
tppubtype = {article}
}
@workshop{Sung2015c,
title = {Data-driven task assignment for multi-vehicle package delivery},
author = {Cynthia Sung and Daniela Rus},
year  = {2015},
date = {2015-10-01},
booktitle = {IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), ECHORD++ Workshop on Urban Robotic Applications},
keywords = {2015},
pubstate = {published},
tppubtype = {workshop}
}
@conference{sung2015automated,
title = {Automated fabrication of foldable robots using thick materials},
author = {Cynthia Sung and Daniela Rus},
doi = {10.1007/978-3-319-51532-8_16},
year  = {2015},
date = {2015-09-09},
booktitle = {International Symposium on Robotics Research},
pages = {253-266},
abstract = {Designing complex machines such as robots often requires multiple iterations of design and prototyping. Folding has recently emerged as a method to both simplify fabrication and accelerate assembly of such machines. However, the robots so far produced by folding have often been made of thin, flexible materials that limit their size and strength. We introduce a folding-based fabrication process that uses thick materials layered with flexible film to enable folding while maintaining high stiffness in the folded structure. We use this process to fabricate multiple solid bodies, as well as two hexapods, one of which can carry up to 2.50 kg payloads. Each folded structure took less than 3 h to construct. Our results indicate that folding using thick materials can be a viable method for rapidly fabricating and prototyping larger and sturdier robots.},
keywords = {2015},
pubstate = {published},
tppubtype = {conference}
}
@workshop{schulz2015interactive,
title = {Interactive Robogami: Data-driven design for 3D print and fold robots with ground locomotion},
author = {Adriana Schulz and Cynthia Sung and Andrew Spielberg and Wei Zhao and Yu Cheng and Ankur Mehta and Eitan Grinspun and Daniela Rus and Wojciech Matusik},
doi = {10.1145/2785585.2792556},
year  = {2015},
date = {2015-08-09},
booktitle = {ACM SIGGRAPH Talks},
pages = {1},
publisher = {ACM},
abstract = {The process of designing and programming a new robot requires expert knowledge and design skills that are often acquired over the course of many years. This makes design of new robots difficult for non-experienced users. In addition to design, physical realization of a robot is also time and labor intensive. We propose a new fabrication process for mechanical robots, called 3D print and fold, which combines 3D printing with origami fabrication methods. In our technique, robots are 3D printed as flat faces connected at joints and are then folded into their final shape. To help casual users design ground robots using our 3D print and fold technique, we present our Interactive Robogami system. The system leverages a database of examples created by expert roboticists. A composition tool allows users to create new designs by composing parts from the robots in this database. The system automatically ensures that the assembled robot is fabricable and that it can locomote forward while still giving creative freedom to users.},
keywords = {2015, computational design},
pubstate = {published},
tppubtype = {workshop}
}
@article{niiyama2015pouch,
title = {Pouch motors: Printable soft actuators integrated with computational design},
author = {Ryuma Niiyama and Xu Sun and Cynthia Sung and Byoungkwon An and Daniela Rus and Sangbae Kim},
doi = {10.1089/soro.2014.0023},
year  = {2015},
date = {2015-06-18},
journal = {Soft Robotics},
volume = {2},
number = {2},
pages = {59-70},
abstract = {We propose pouch motors, a new family of printable soft actuators integrated with computational design. The pouch motor consists of one or more inflatable gas-tight bladders made of sheet materials. This printable actuator is designed and fabricated in a planar fashion. It allows both easy prototyping and mass fabrication of affordable robotic systems. We provide theoretical models of the actuators compared with the experimental data. The measured maximum stroke and tension of the linear pouch motor are up to 28% and 100 N, respectively. The measured maximum range of motion and torque of the angular pouch motor are up to 80° and 0.2 N, respectively. We also develop an algorithm that automatically generates the patterns of the pouches and their fluidic channels. A custom-built fabrication machine streamlines the automated process from design to fabrication. We demonstrate a computer-generated life-sized hand that can hold a foam ball and perform gestures with 12 pouch motors, which can be fabricated in 15 min.},
keywords = {2015},
pubstate = {published},
tppubtype = {article}
}
@conference{sung2015reconfiguration,
title = {Reconfiguration planning for pivoting cube modular robots},
author = {Cynthia Sung and James Bern and James Romanishin and Daniela Rus},
doi = {10.1109/ICRA.2015.7139451},
year  = {2015},
date = {2015-05-26},
booktitle = {IEEE International Conference on Robotics and Automation (ICRA)},
pages = {1933-1940},
abstract = {In this paper, we present algorithms for self-reconfiguration of modular robots that move by pivoting. The modules are cubes that can pivot about their edges along the x̂, ŷ, or ẑ axes to move on a 3-dimensional substrate. This is a different model from prior work, which usually considers modules that slide along their faces. We analyze the pivoting cube model and give sufficient conditions for reconfiguration to be feasible. In particular, we show that if an initial configuration does not contain any of three subconfigurations, which we call rules, then it can reconfigure into a line. We provide provably correct algorithms for reconfiguration for both 2-D and 3-D systems, and we verify our algorithms via simulation on randomly generated 2-D and 3-D configurations.},
keywords = {2015},
pubstate = {published},
tppubtype = {conference}
}
@conference{miyashita2015untethered,
title = {An untethered miniature origami robot that self-folds, walks, swims, and degrades},
author = {Shuhei Miyashita and Steven Guitron and Marvin Ludersdorfer and Cynthia Sung and Daniela Rus},
doi = {10.1109/ICRA.2015.7139386},
year  = {2015},
date = {2015-05-26},
booktitle = {IEEE International Conference on Robotics and Automation (ICRA)},
pages = {1490-1496},
publisher = {IEEE},
abstract = {A miniature robotic device that can fold-up on the spot, accomplish tasks, and disappear by degradation into the environment promises a range of medical applications but has so far been a challenge in engineering. This work presents a sheet that can self-fold into a functional 3D robot, actuate immediately for untethered walking and swimming, and subsequently dissolve in liquid. The developed sheet weighs 0.31 g, spans 1.7 cm square in size, features a cubic neodymium magnet, and can be thermally activated to self-fold. Since the robot has asymmetric body balance along the sagittal axis, the robot can walk at a speed of 3.8 body-length/s being remotely controlled by an alternating external magnetic field. We further show that the robot is capable of conducting basic tasks and behaviors, including swimming, delivering/carrying blocks, climbing a slope, and digging. The developed models include an acetone-degradable version, which allows the entire robot's body to vanish in a liquid. We thus experimentally demonstrate the complete life cycle of our robot: self-folding, actuation, and degrading.},
keywords = {2015},
pubstate = {published},
tppubtype = {conference}
}
@article{sung2015foldable,
title = {Foldable joints for foldable robots},
author = {Cynthia Sung and Daniela Rus},
doi = {10.1115/1.4029490},
year  = {2015},
date = {2015-02-27},
journal = {ASME Journal of Mechanisms and Robotics},
volume = {7},
number = {2},
pages = {021012},
abstract = {Print-and-fold manufacturing has the potential to democratize access to robots with robots that are easier to fabricate using materials that are easier to procure. Unfortunately, a lack of understanding about how motion can be achieved by folding hinders the scope of print-and-fold robots. In this paper, we show how the basic joints used in robots can be constructed using print-and-fold. Our patterns are parameterized so that users not only get the desired degrees of freedom but can also specify the joint's range of motion. The joints can be combined with each other to achieve higher degrees of freedom or with rigid bodies to produce foldable linkages. We have folded our basic joints and measured their force–displacement curves. We have composed them into joints with higher degrees of freedom and into foldable mechanisms and found that they achieve the expected kinematics. We have also added actuators and control circuitry to our joints and mechanisms, showing that it is possible to print and fold entire robots with many different kinematics using a uniform process.},
keywords = {2015},
pubstate = {published},
tppubtype = {article}
}
@article{miyashita2015folding,
title = {Folding angle regulation by curved crease design for self-assembling origami propellers},
author = {Shuhei Miyashita and Isabello DiDio and Ishwarya Ananthabhotla and Byoungkwon An and Cynthia Sung and Slava Arabagi and Daniela Rus},
doi = {10.1115/1.4029548},
year  = {2015},
date = {2015-02-27},
journal = {ASME Journal of Mechanisms and Robotics},
volume = {7},
number = {2},
pages = {021013},
abstract = {This paper describes a method for manufacturing complex three-dimensional curved structures by self-folding layered materials. Our main focus is to first show that the material can cope with curved crease self-folding and then to utilize the curvature to predict the folding angles. The self-folding process employs uniform heat to induce self-folding of the material and shows the successful generation of several types of propellers as a proof of concept. We further show the resulting device is functional by demonstrating its levitation in the presence of a magnetic field applied remotely.},
keywords = {2015},
pubstate = {published},
tppubtype = {article}
}
@conference{Sung2014,
title = {Foldable joints for foldable robots},
author = {Cynthia Sung and Daniela Rus},
doi = {10.1007/978-3-319-23778-7_28},
year  = {2014},
date = {2014-06-15},
booktitle = {International Symposium on Experimental Robotics (ISER)},
pages = {421-433},
abstract = {Print-and-fold approaches to robot fabrication allow entire
robots to be produced using a single uniform process: fabricating them
in-plane and then folding them into their 3-D forms. Current efforts to
design print-and-fold robots have been limited by a lack of understanding
of what motions can be achieved by folding. In this paper, we introduce
fold patterns for three basic joints commonly used in robots, and we
show how the patterns can be changed to accommodate user-specified
ranges of motion. The joints are composed with each other to produce
joints with higher degrees of freedom and with rigid bodies to produce
entire foldable linkage mechanisms. We have folded our basic joints and
composed mechanisms, and they achieve the expected kinematics. We
have also printed control circuitry on and attached actuators directly
to three of our designs, demonstrating that it possible to print and fold
robots with many different kinematics.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
@conference{feldman2013idiary,
title = {iDiary: From GPS signals to a text-searchable diary},
author = {Dan Feldman and Andrew Sugaya and Cynthia Sung and Daniela Rus},
doi = {10.1145/2517351.2517366},
year  = {2013},
date = {2013-11-11},
booktitle = {11th ACM Conference on Embedded Networked Sensor Systems (SenSys)},
pages = {6},
publisher = {ACM},
abstract = {This paper describes a system that takes as input GPS data streams generated by users' phones and creates a searchable database of locations and activities. The system is called iDiary and turns large GPS signals collected from smartphones into textual descriptions of the trajectories. The system features a user interface similar to Google Search that allows users to type text queries on their activities (e.g., "Where did I buy books?") and receive textual answers based on their GPS signals.

iDiary uses novel algorithms for semantic compression (known as coresets) and trajectory clustering of massive GPS signals in parallel to compute the critical locations of a user. Using an external database, we then map these locations to textual descriptions and activities so that we can apply text mining techniques on the resulting data (e.g. LSA or transportation mode recognition).

We provide experimental results for both the system and algorithms and compare them to existing commercial and academic state-of-the-art. This is the first GPS system that enables text-searchable activities from GPS data.},
keywords = {2013},
pubstate = {published},
tppubtype = {conference}
}
@article{sung2013edge,
title = {Edge-compositions of 3-D surfaces},
author = {Cynthia Sung and Erik D. Demaine and Martin L. Demaine and Daniela Rus},
doi = {10.1115/1.4025378},
year  = {2013},
date = {2013-09-24},
journal = {ASME Journal of Mechanical Design},
volume = {135},
number = {11},
pages = {111001},
abstract = {Origami-based design methods enable complex devices to be fabricated quickly in plane and then folded into their final 3D shapes. So far, these folded structures have been designed manually. This paper presents a geometric approach to automatic composition of folded surfaces, which will allow existing designs to be combined and complex functionality to be produced with minimal human input. We show that given two surfaces in 3D and their 2D unfoldings, a surface consisting of the two originals joined along an arbitrary edge can always be achieved by connecting the two original unfoldings with some additional linking material, and we provide a polynomial-time algorithm to generate this composite unfolding. The algorithm is verified using various surfaces, as well as a walking and gripping robot design.},
keywords = {2013},
pubstate = {published},
tppubtype = {article}
}
@conference{sung2013joining,
title = {Joining unfoldings of 3-D surfaces},
author = {Cynthia Sung and Erik D. Demaine and Martin L. Demaine and Daniela Rus},
doi = {10.1115/DETC2013-12692},
year  = {2013},
date = {2013-08-04},
booktitle = {ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference (IDETC/CIE)},
pages = {DETC2013-12692},
publisher = {ASME},
abstract = {Origami-based design methods enable complex devices to be fabricated quickly in plane and then folded into their final 3-D shapes. So far, these folded structures have been designed manually. This paper presents a geometric approach to automatic composition of folded surfaces, which will allow existing designs to be combined and complex functionality to be produced with minimal human input. We show that given two surfaces in 3-D and their 2-D unfoldings, a surface consisting of the two originals joined along an arbitrary edge can always be achieved by connecting the two original unfoldings with some additional linking material, and we provide an algorithm to generate this composite unfolding. The algorithm is verified using various surfaces, as well as a walking and gripping robot design.},
keywords = {2013},
pubstate = {published},
tppubtype = {conference}
}
@conference{sung2013improving,
title = {Improving the performance of multi-robot systems by task switching},
author = {Cynthia Sung and Nora Ayanian and Daniela Rus},
doi = {10.1109/ICRA.2013.6630993},
year  = {2013},
date = {2013-05-06},
booktitle = {IEEE International Conference on Robotics and Automation (ICRA)},
pages = {2999-3006},
publisher = {IEEE},
abstract = {We consider the problem of task assignment for a multi-robot system where each robot must attend to one or more queues of tasks. We assume that individual robots have no knowledge of tasks in the environment that are not in their queue. Robots in communication with each other may share information about active tasks and exchange queues to achieve lower cost for the system. We show that allowing this kind of task switching causes tasks to be completed more efficiently. In addition, we present conditions under which queues can be guaranteed to make progress, and we support these claims with simulation and experimental results. This work has potential applications in manufacturing, environmental exploration, and pickup-delivery tasks.},
keywords = {2013},
pubstate = {published},
tppubtype = {conference}
}
@workshop{wu2013using,
title = {Using coresets for map making for long-term operation of robots},
author = {Cathy Wu and Dan Feldman and Cynthia Sung and Daniela Rus},
year  = {2013},
date = {2013-05-06},
booktitle = {IEEE International Conference on Robotics and Automation (ICRA), Workshop on Long-Term Autonomy},
keywords = {2013},
pubstate = {published},
tppubtype = {workshop}
}
@conference{feldman2012single,
title = {The single pixel GPS: Learning big data signals from tiny coresets},
author = {Dan Feldman and Cynthia Sung and Daniela Rus},
doi = {10.1145/2424321.2424325},
year  = {2012},
date = {2012-11-06},
booktitle = {20th ACM SIGSPATIAL International Conference on Advances in Geographic Information Systems (GIS 2012)},
pages = {23-32},
publisher = {ACM},
abstract = {We present algorithms for simplifying and clustering patterns from sensors such as GPS, LiDAR, and other devices that can produce high-dimensional signals. The algorithms are suitable for handling very large (e.g. terabytes) streaming data and can be run in parallel on networks or clouds. Applications include compression, denoising, activity recognition, road matching, and map generation.

We encode these problems as (k, m)-segment mean problems. Formally, we provide (1 + ε)-approximations to the k-segment and (k, m)-segment mean of a d-dimensional discrete-time signal. The k-segment mean is a k-piecewise linear function that minimizes the regression distance to the signal. The (k,m)-segment mean has an additional constraint that the projection of the k segments on Rd consists of only m ≤ k segments. Existing algorithms for these problems take O(kn2) and nO(mk) time respectively and O(kn2) space, where n is the length of the signal.

Our main tool is a new coreset for discrete-time signals. The coreset is a smart compression of the input signal that allows computation of a (1 + ε)-approximation to the k-segment or (k,m)-segment mean in O(n log n) time for arbitrary constants ε,k, and m. We use coresets to obtain a parallel algorithm that scans the signal in one pass, using space and update time per point that is polynomial in log n. We provide empirical evaluations of the quality of our coreset and experimental results that show how our coreset boosts both inefficient optimal algorithms and existing heuristics. We demonstrate our results for extracting signals from GPS traces. However, the results are more general and applicable to other types of sensors.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
@conference{sung2012trajectory,
title = {Trajectory clustering for motion prediction},
author = {Cynthia Sung and Dan Feldman and Daniela Rus},
doi = {10.1109/IROS.2012.6386017},
year  = {2012},
date = {2012-10-07},
booktitle = {IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS)},
pages = {1547-1552},
publisher = {IEEE},
abstract = {We investigate a data-driven approach to robotic path planning and analyze its performance in the context of interception tasks. Trajectories of moving objects often contain repeated patterns of motion, and learning those patterns can yield interception paths that succeed more often. We therefore propose an original trajectory clustering algorithm for extracting motion patterns from trajectory data and demonstrate its effectiveness over the more common clustering approach of using k-means. We use the results to build a Hidden Markov Model of a target's motion and predict movement. Our simulations show that these predictions lead to more effective interception. The results of this work have potential applications in coordination of multi-robot systems, tracking and surveillance tasks, and dynamic obstacle avoidance.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}