Abstract: The joint is a fundamental element of mechanical system of bionic robot. Within the bionic robot system toward environment interaction, the mass, volume and ratio of power/weight have impact on the performance of system. Compared to electrical and hydraulic drive, the method driven by pneumatic muscles has broad application prospect due to its lighter weight, smaller volume and larger ratio of power/weight. From the prospective function bionics, an antagonistic bionic joint driven by pneumatic muscles is designed based on the analysis of natural skeleton structure and strength generation of elbow joint. The model of pneumatic muscle is established. The performance test of pneumatic muscle is carried out on the experiment platform. The parameters of the model is identified though least square method. Directed by kinematics and dynamics analysis, a model-based control strategy of input pressure offset is proposed. The disturbance observer based on damping estimation is introduced for torque compensation of nominal model. The proposed strategy is verified by simulation. Furthermore, the test system of joint motion control is constructed. The validity of the theoretical model of pneumatic muscles and controller is testified by tracking experiments.

Key words: Bionic joint, Disturbance observer, Motion control, Pneumatic muscles