Bipedal walking control based on Capture Point dynamics

Abstract

This paper builds up on the Capture Point concept and exploits the simple form of the dynamical equations of the Linear Inverted Pendulum model when formulated in terms of the center of mass and the Capture Point. The presented methods include (i) the derivation of a Capture Point (CP) control principle based on the natural dynamics of the linear inverted pendulum (LIP), which stabilizes the walking robot and motivates (ii) the design of a CP tracking and a CP endof-step controller. The exponential stability of the CP control law is proven. Tilting is avoided by proper projection of the commanded zero moment point. The robustness of the derived control algorithms is analyzed analytically and verified in simulation and experiments.

Trajectory generation for continuous leg forces during double support and heel-to-toe shift based on divergent component of motion

“…Introduction of three-dim. DCM, eCMP and VRP Motivated by the performance of 2D Capture Point (= DCM) control [13], [14], the three-dimensional Divergent Component of Motion (DCM) was introduced as…”

Balance control based on Capture Point error compensation for biped walking on uneven terrain

“…The CP controller is proposed by Englsberger [9] and, the CP controller without the COG controller also could stabilize a biped robot. In this method, the CP controller and the ZMP controller were designed independently.…”

“…A landing position is modified to prevent losing a balance according to a divergent component as a result of the model ZMP control which accelerates the upper body. Mitsuharu Englsberger et al [9] introduced two approaches for Capture Point control as balance control. This paper focuses on a balance control of biped walking on uneven terrain.…”

“…Thus, the CP integration is introduced to solve this problem. We try to improve a balance controller based on the similar type of the Capture Point control [9]. First the characteristics of the conventional balance controller is shown to be essentially the same as the CP controller.…”

Optimal use of arm-swing for bipedal walking control

“…It is mainly composed of mechanical stability and moving efficiency. To enhance walking capability under the constraints from limited body, two approaches have been considered: (i) an optimal design of the center of gravity (COG) trajectory by a control of the support leg like [1]- [3] and (ii) an effective use of the whole body, especially arms. The latter approach can be expected to achieve higher walking capability than the case of using only support leg.…”