Inverse dynamics with optimal distribution of ground reaction forces for legged robots

The control of the interaction of legged robots with their environment is of crucial importance in the design of locomotion controllers. We need to control the effects of the robots movement on the contact reaction forces to prevent slipping, for example. In this contribution, we extend a recent inverse dynamics algorithm for floating base robots to optimize the distribution of contact forces while achieving precise trajectory tracking. The resulting controller is algorithmically simple as compared to other approaches. Numerical simulations show that this result significantly increases the range of possible movements of a humanoid robot as compared to the previous inverse dynamics algorithm. We also present a simplification of the result for practical use on a real robot. Such an algorithm becomes particularly relevant for agile locomotion of robots on difficult terrains where the contacts with the environment are critical, such as walking over rough or slippery terrain.