Non-Linear Phase Different Control to improve dynamics of bi-articularly actuated manipulators

There is a rising interest in bi-articular actuation for solving the known limitations of conventional robot arms. Actuator redundancy resulting from bi-articular actuation bring advantages such as increasing movement stability and efficiency in end effector force production. Actuator redundancy resolution is the first step in the control design for these robots, representing a key aspect for their performances. The Phase Different Control (PDC) resolves actuator redundancy on the basis of a linearized model derived from measured human muscle activity. Such linear model produces a non zero error in calculation between a desired output force and necessary inputs. In our previous work, the Non-Linear Phase Different Control (NLPDC) has been proposed to resolve actuator redundancy with no error under static conditions. In this work, NLPDC is implemented under dynamic conditions, and compared with PDC by simulating the dynamics a two-link planar arm. Performances such ad settling time and position error are highly improved when using NLPDC.