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arXiv · 2501.18956

Differentiable Simulation of Soft Robots with Frictional Contacts

Etienne Ménager·Louis Montaut·Quentin Le Lidec·Justin Carpentier
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Abstract

In recent years, soft robotics simulators have evolved to offer various functionalities, including the simulation of different material types (e.g., elastic, hyper-elastic) and actuation methods (e.g., pneumatic, cable-driven, servomotor). These simulators also provide tools for various tasks, such as calibration, design, and control. However, efficiently and accurately computing derivatives within these simulators remains a challenge, particularly in the presence of physical contact interactions. Incorporating these derivatives can, for instance, significantly improve the convergence speed of control methods like reinforcement learning and trajectory optimization, enable gradient-based techniques for design, or facilitate end-to-end machine-learning approaches for model reduction. This paper addresses these challenges by introducing a unified method for computing the derivatives of mechanical equations within the finite element method framework, including contact interactions modeled as a nonlinear complementarity problem. The proposed approach handles both collision and friction phases, accounts for their nonsmooth dynamics, and leverages the sparsity introduced by mesh-based models. Its effectiveness is demonstrated through several examples of controlling and calibrating soft systems.

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Etienne Ménager, Louis Montaut, Quentin Le Lidec, Justin Carpentier. 2025-01-31. Differentiable Simulation of Soft Robots with Frictional Contacts. https://arxiv.org/abs/2501.18956

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