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Nonlinear Stochastic Trajectory Optimization for Centroidal Momentum Motion Generation of Legged Robots
Generation of robust trajectories for legged robots remains a challenging task due to the underlying nonlinear, hybrid and intrinsically unstable dynamics which needs to be stabilized through limited contact forces. Furthermore, disturbances arising from unmodelled contact interactions with the environment and model mismatches can hinder the quality of the planned trajectories leading to unsafe motions. In this work, we propose to use stochastic trajectory optimization for generating robust centroidal momentum trajectories to account for additive uncertainties on the model dynamics and parametric uncertainties on contact locations. Through an alternation between the robust centroidal and whole-body trajectory optimizations, we generate robust momentum trajectories while being consistent with the whole-body dynamics. We perform an extensive set of simulations subject to different uncertainties on a quadruped robot showing that our stochastic trajectory optimization problem reduces the amount of foot slippage for different gaits while achieving better performance over deterministic planning.
@inproceedings{AGazar_ISRR_2022, title = {Nonlinear Stochastic Trajectory Optimization for Centroidal Momentum Motion Generation of Legged Robots}, booktitle = {Robotics Research}, abstract = { Generation of robust trajectories for legged robots remains a challenging task due to the underlying nonlinear, hybrid and intrinsically unstable dynamics which needs to be stabilized through limited contact forces. Furthermore, disturbances arising from unmodelled contact interactions with the environment and model mismatches can hinder the quality of the planned trajectories leading to unsafe motions. In this work, we propose to use stochastic trajectory optimization for generating robust centroidal momentum trajectories to account for additive uncertainties on the model dynamics and parametric uncertainties on contact locations. Through an alternation between the robust centroidal and whole-body trajectory optimizations, we generate robust momentum trajectories while being consistent with the whole-body dynamics. We perform an extensive set of simulations subject to different uncertainties on a quadruped robot showing that our stochastic trajectory optimization problem reduces the amount of foot slippage for different gaits while achieving better performance over deterministic planning. }, pages = {420--435}, series = {Springer Proceedings in Advanced Robotics, 27}, editors = {Billard, Aude and Asfour, Tamim and Khatib, Oussama}, publisher = {Springer}, address = {Cham}, month = sep, year = {2022}, slug = {gazar_isrr_2022}, author = {Gazar, Ahmad and Khadiv, Majid and Kleff, Sébastien and DelPrete, Andrea and Righetti, Ludovic}, url = {https://doi.org/10.48550/arXiv.2205.13264}, month_numeric = {9} }