Model-based controller design for antagonistic pairs of fluidic muscles in manipulator motion control

A control structure is presented for manipulators actuated by joints with pairwise antagonistic pneumatic muscles. The used muscles and the resulting behavior of a single manipulator joint featuring antagonistic muscles in a symmetric configuration are characterized. Pneumatic joint actuation results in a hysteretic behavior, it is shown that in this case the hysteresis can be described by a Preisach hysteresis model. The resulting hysteresis model allows the construction of a model-reference following controller, with a model control loop, designed for good tracking performance and a disturbance rejection loop optimized for suppression of disturbances. Experiments confirm the improvement in tracking control as compared to the system solely controlled by a feedback regulator.