Hope to see everyone in Philly this May!

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.

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.

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.