30 Degree of Freedom robot Climbing Steep Stairs - IHMC Robotics - DARPA Robotics Challenge

A 30 DoF simulated test robot climbing stairs with a rise of 35 cm and a tread of only 15 cm at a rate of 7.9 seconds per ten steps. Stairs this steep disallow the use of the full foot polygon to balance on a step by CoP placement, forcing us to focus on the use of angular momentum and improved weight distribution algorithms for balance control. In addition, combined ground reaction force control and foot orientation control is necessary, where the orientation of the foot is constrained by the line contact with the step. We are also able to climb variable height stairs. Stair climbing fits nicely into our momentum and instantaneous capture point based control framework. In addition, almost the same high level behavior is used for flat ground walking and stair climbing, with only minor modifications to e.g. center of mass height trajectories. We plan to make full use of the algorithms developed for varying height stairs in the DRC, enabling dynamic, extremely rough terrain locomotion.