On Local Active Compliance Control Strategy for a Redundant Prototype Leg of Hydraulic-Driving Quadruped Robot

The leg control on foot trajectory planning and contact forces is the most crucial problem for a hydraulic quadruped robot. In contrast with a non-redundant leg, the redundant one generally has larger foot workspace and more agility for leg motion control in rough terrain, however, this redundant joint obviously adds complexities and difficulties to the control system. This work aims to avoid those disadvantages but not apparently affect the designed performance indices of the redundant leg. Thus, based on the control problems of a redundant prototype leg, a novel local active compliance control strategy is proposed for the first time ever. Works presented in this paper mainly includes modeling for a planar redundant leg, selecting desired joint on a redundant leg by solving optimization model, designing local active compliance controller and discussing the constraints on implementing the proposed control strategy. Final experiments prove the proposed strategy feasible and effective.