Constraint-based dynamics simulator for humanoid robots with shock absorbing mechanisms

We propose a simulation system that achieves realistic and efficient simulations of humanoid robots. This paper focuses on a constraint-based contact force solver and virtual spring-damper joints from among the components of the system. The contact force solver can accurately simulate contacts between rigid bodies including articulated rigid bodies. LCP-like formulation of constraint conditions is solved by an iterative calculation method that extends the Gauss-Seidel method. This paper clarifies how to integrate existing methods to implement a robust and efficient solver. Virtual spring-damper joints are proposed to simulate a shock absorbing mechanism that many biped humanoid robots have in their feet to increase the stability of walking motion. The combination of the rigid contact model and the elastic virtual joints can improve the accuracy of the simulation. The simulation system was verified by experiments using humanoid robot HRP-2, and the results shows the validity of the system.