Position and compliance control of an artificial muscle manipulator using a mechanical equilibrium model

Robots have entered human life, and closer relationships are being formed between humans and robots. It is desirable that these robots be flexible and lightweight. For this reason, we studied and developed an artificial muscle actuator using straight-fiber-type artificial muscles derived from the McKibben-type muscles, which have excellent contraction rate and force characteristics. However, these muscles have highly nonlinear characteristics, as well as high compliance and a strong hysteresis characteristic. Hence, it is difficult to control the artificial muscle manipulator. In this study, a mechanical equilibrium model is introduced to control this manipulator, and the position control characteristic is linearized, making compliance control possible. In addition, considering dynamic characteristics of the artificial muscle, we apply an “inner model control” for position control.