Dynamic walking in a humanoid robot based on a 3D Actuated Dual-SLIP model

This paper presents a method for the generation of dynamic walking gaits with a 3D Dual-SLIP model and its application to a simulated Hubo+ based humanoid. Previous approaches with the Dual-SLIP model have only focused on the planar case, wherein self-stable gaits can be found. When extended to 3D here, this model has not been found to exhibit self-stable gaits, requiring new methods for gait optimization and control. By taking advantage of a newly discovered symmetry condition for the Dual-SLIP model, this work proposes a quarter period (half step) optimization process to find periodic walking gaits in 3D. An LQR controller is developed to regulate the state of the model at leg midstance (MS) based on its return map dynamics. The Dual-SLIP model is extended by introducing a bio-inspired leg length actuation scheme in order to describe high-speed walking gaits (up to 2 m/s for human-compatible parameters). Finally, the CoM trajectory and footstep positions from the 3D Dual-SLIP are used as a reference in a task-space controller with a Hubo+ based humanoid model. By tracking these references, the methods successfully produce human-like dynamic walking gaits in simulation which are robust to disturbances. The whole-body control system for walking can handle uneven terrain with variation up to 10% of its leg length. This represents the first humanoid dynamic walking approach based on a 3D Dual-SLIP model.