An Approach to Combine Balancing with Hierarchical Whole-Body Control for Legged Humanoid Robots

Legged humanoid robots need to be able to perform a variety of tasks including interaction with the environment while maintaining the balance. The external wrenches, which arise from the physical interaction, must be taken into account in order to achieve robust and compliant balancing. This work presents a new control approach for combining multiobjective hierarchical control based on null space projections with passivity-based multicontact balancing for legged humanoid robots. In order to achieve a proper balancing, all task forces/torques are first distributed to the end effectors and then mapped into joint space considering the task hierarchy. The control approach is evaluated both in simulation and experiment with the humanoid robot TORO.