Straight-Leg Walking Through Underconstrained Whole-Body Control

Abstract

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.

A fast parameterized gait planning method for a lower-limb exoskeleton robot

“…Nearly all bipedal robot walking gaits utilize highly bent knees, not only is this highly unnatural, it results in significant increase in power consumption at the knee compared to humans. 16 Therefore, the gait planning method of lower-limb exoskeleton robots cannot directly adopt the gait planning method of biped robots, and the gait of lower-limb exoskeleton robots must be humanlike and straight-leg. Referring to the recent several excellent research on straight-leg walking of biped robots, 16,17 this article adopts the linear inverted pendulum model to ensure that the robot has certain stability and is human-like.…”

Torso height optimization for bipedal locomotion

“…Trying to imitate the human walking, Hu et al 18 generate the CoM height motion indirectly by introducing angle objectives in the quadratic optimization program which is solved by their motion controller as well. Both publications 17,18 do not take into account future motion limits. They consider only the current controller time step, and they do not optimize over a motion sequence as, for example, a physical step of the robot.…”

Dynamic and Versatile Humanoid Walking via Embedding 3D Actuated SLIP Model With Hybrid LIP Based Stepping

“…The generated walking is first featured to be dynamic (less conservative) with the variation on the COM height. Compared to existing methods for generating the COM height variation in [15], [16] via the kinematic structuring on the leg extension, the aSLIP embedding provides coherent trajectories at the dynamics level. Moreover, the versatile motion generation via the H-LIP based stepping is highly efficient.…”