Bio-inspired cooperative control for robotic joint actuated via sequential recruitment of multiple pneumatic artificial muscles

Pneumatic artificial muscles (PAMs) are expected to play an important role in endowing the advanced robot with the compliant manipulation. Though, PAMs can produce hundreds or even thousands of newtons of output force, their contraction length is limited. This limits the radius of the pulley of the robot joint in the classic PAMs antagonistic actuator system, which results in the limitation of the output torque of the robot joint. In this article, we propose a cooperative sequential recruitment driving plan and control algorithm for a robotic joint multistagely actuated by multiple PAMs. Physical experiments are presented to validate the advantages of the proposed robot joint design scheme as well as the cooperative control algorithm: It can not only generate a much larger driving torque for the joint, but also realize smooth cooperative transition among the multiple antagonistic PAM pairs, consequently it can achieve the human-like motion on a robotic joint. Therefore, we suggest that both the proposed robot joint design scheme and the cooperative control algorithm can be widely applied to the PAMs actuated robotic system for better human-robot cooperation.