Fractional Order Impedance Control

This paper proposes a novel fractional order impedance control. In traditional impedance control model, the orders of inertia, damping, and stiffness are integers and the contact force can be reduced effectively to some extent in robots and manipulators. However, there exists a tracking error of end-effector at the stable state due to the existence of stiffness, which is not conducive to tackle tasks based on high performance position control for robots and manipulators. Thus, an integral item is added into the traditional impedance model to eliminate the tracking error. Besides, the idea of fractional order is introduced to make the orders of inertia, damping, and stiffness change from integers to fractions to achieve more significant compliant performance. Simulation results validate the advantages of proposed fractional order impedance control and it can be also employed to absorb/increase, hold/keep, and dissipate/decrease system energy to achieve jumping, bouncing and friendly contact, respectively. Also, three criterions of choosing and tuning all these 14 parameters in the proposed fractional order impedance control are given out. This provides an insight for robot dynamic interaction, bouncing and jumping control.