Design and control of the bionic ankle joint with multiple pneumatic artificial muscles

To address the time-varying output force and compliance issues in pneumatic artificial muscle-driven robots, this paper proposes a bionic ankle joint inspired by human muscle structure. By recruiting multiple pneumatic artificial muscles and implementing compliance control, the overall output performance is enhanced. This study presents the structural design of the bionic ankle joint with multiple pneumatic artificial muscles and analyses its bionic actuation mechanism. Furthermore, impedance control and adaptive impedance control models are developed, followed by a simulation-based analysis of the output angular characteristics and force response. A performance evaluation platform is constructed for experimental validation. The results indicate that the bionic ankle joint with adaptive impedance control effectively reduces angular tracking errors and output force deviations, while improving joint compliance.