Straight-Leg Walking Through Underconstrained Whole-Body Control
This addresses gait efficiency for bipedal robots, but appears incremental as it builds on whole-body control methods.
The paper tackled the problem of achieving a natural, efficient gait on bipedal robots by using straightened legs and toe-off, resulting in successful walking over varied terrain on the Atlas humanoid with experimental and simulation validation.
We present an approach for achieving a natural, efficient gait on bipedal robots using straightened legs and toe-off. Our algorithm avoids complex height planning by allowing a whole-body controller to determine the straightest possible leg configuration at run-time. The controller solutions are biased towards a straight leg configuration by projecting leg joint angle objectives into the null-space of the other quadratic program motion objectives. To allow the legs to remain straight throughout the gait, toe-off was utilized to increase the kinematic reachability of the legs. The toe-off motion is achieved through underconstraining the foot position, allowing it to emerge naturally. We applied this approach of under-specifying the motion objectives to the Atlas humanoid, allowing it to walk over a variety of terrain. We present both experimental and simulation results and discuss performance limitations and potential improvements.