An Integrated Motion Planner/Controller for Humanoid Robots on Uneven Ground

We consider a situation in which a humanoid robot must reach a goal region (walk-to task) walking in an environment consisting of horizontal patches located at different heights (world of stairs). To solve this problem, the paper proposes an integrated motion planner/controller working in two stages: off-line footstep planning and on-line gait generation. The planning stage is based on a randomized algorithm that efficiently searches for a feasible footstep sequence. The gait generation uses an intrinsically stable MPC-based control scheme which computes CoM trajectories that are suitable for walking on uneven ground. The proposed framework was implemented in the V-REP environment for the HRP4 humanoid robot and successfully tested via simulations.