Wertz, AnthonySabelhaus, Andrew P.Majidi, Carmel2022-09-292022-09-292022-04-04A. Wertz, A.P. Sabelhaus, C. Majidi. 2022. "Trajectory Optimization for Thermally-Actuated Soft Planar Robot Limbs." 2022 IEEE 5th International Conference on Soft Robotics (RoboSoft). 2022 IEEE 5th International Conference on Soft Robotics (RoboSoft). 2022-04-04 - 2022-04-08. https://doi.org/10.1109/robosoft54090.2022.9762226https://hdl.handle.net/2144/45206Practical use of robotic manipulators made from soft materials requires generating and executing complex motions. We present the first approach for generating trajectories of a thermally-actuated soft robotic manipulator. Based on simplified approximations of the soft arm and its antagonistic shape-memory alloy actuator coils, we justify a dynamics model of a discretized rigid manipulator with joint torques proportional to wire temperature. Then, we propose a method to calibrate this model from experimental data and demonstrate that the simulation aligns well with a hardware test. Finally, we use a direct collocation optimization with the robot's nonlinear dynamics to generate feasible state-input trajectories from a desired reference. Three experiments validate our approach for a single-segment robot in hardware: first using a hand-derived reference trajectory, then with two teach-and-repeat tests. The results show promise for both open-loop motion generation as well as for future applications with feedback.en-USConference materials10.1109/robosoft54090.2022.9762226747751