论文标题

添加:具有摩擦接触的多体系统的分析上可区分的动力学

ADD: Analytically Differentiable Dynamics for Multi-Body Systems with Frictional Contact

论文作者

Geilinger, Moritz, Hahn, David, Zehnder, Jonas, Bächer, Moritz, Thomaszewski, Bernhard, Coros, Stelian

论文摘要

我们提出了一个可区分的动力求解器,该求解器能够处理统一框架内的刚性和可变形对象的摩擦联系。通过对正常和切向接触力的原则性化,我们的方法规避了摩擦接触的非平滑性质固有的主要困难。我们将这个新的接触模型与完全显式的时间集成结合在一起,以获得可在分析上可区分的强大而有效的动力求解器。结合伴随灵敏度分析,我们的公式可实现基于梯度的优化,并在仿真精度和目标函数景观的平滑度之间进行自适应权衡。我们在一组涉及刚体,粘弹性材料和耦合多体系统的模拟示例上彻底分析了我们的方法。我们进一步展示了可区分的模拟器对可变形对象的参数估计的应用,机器人操纵的运动计划,合并的步行机器人的轨迹优化以及对控制策略的有效自我监督学习。

We present a differentiable dynamics solver that is able to handle frictional contact for rigid and deformable objects within a unified framework. Through a principled mollification of normal and tangential contact forces, our method circumvents the main difficulties inherent to the non-smooth nature of frictional contact. We combine this new contact model with fully-implicit time integration to obtain a robust and efficient dynamics solver that is analytically differentiable. In conjunction with adjoint sensitivity analysis, our formulation enables gradient-based optimization with adaptive trade-offs between simulation accuracy and smoothness of objective function landscapes. We thoroughly analyse our approach on a set of simulation examples involving rigid bodies, visco-elastic materials, and coupled multi-body systems. We furthermore showcase applications of our differentiable simulator to parameter estimation for deformable objects, motion planning for robotic manipulation, trajectory optimization for compliant walking robots, as well as efficient self-supervised learning of control policies.

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