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Maximum Stability Trajectory Planning for Motions with Signi cant Rotational Accelerations


F. Tobler

Master Thesis, FS14 (10327)

This thesis is inspired by a class of motions intended to being used by the Jet Propulsion Laboratory's robot RoboSimian in the ongoing DARPA Robotics Challenge. This class of motions consists of rotational accelerations that signi cantly a ect the center of pressure location. A new approach for the joint trajectory planning for such motions is applied and tested in this thesis. In particular the motions of the transition between bent-over and upright position of humanoid robots such as RoboSimian are of interest. The rotational accelerations which are part of such motions may a ect the location of the center of pressure and thus the dynamic stability for robots with limited base of support. This thesis thus aims to generate maximum stability joint trajectories for such motions: while meeting the actuator limits and keeping actuator torque as low as possible the goal is having least deviation possible of the center of pressure from the maximum stability center of pressure location. The joint trajectories are generated applying LQR controllers on under-actuated three-link models. The trajectories are then played back on the fully actuated models. Combining several controllers allows to further increase speed while decreasing actuator torque. In a second step the robustness to model parameter inaccuracies is analyzed. The results indicate that reference trajectories generated using multiple LQR controllers can, with carefully selected LQR values, lead to minimal center of pressure deviations in case of model parameter inaccuracies. The comparison with two other approaches for the joint trajectory planning of such motions shows that using the proposed method enables the reduction of center of pressure deviations and required actuator torque to a minimum.


Type of Publication:

(12)Diploma/Master Thesis

J. Lygeros

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% Autogenerated BibTeX entry
@PhdThesis { Xxx:2014:IFA_4884
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