Realization of Fractional Order Impedance by Feedback Control

Fractional order impedance control is proposed in this paper to control power assistive devices in more human friendly way. A novel discretization method of a fractional order integrator is proposed based on a multirate filter approach. Optimal coefficients for the multirate fractional order integrator are decided using golden-ratio particle swarm optimization. Based on this fractional order integrator, fractional order impedance control is realized using feedback control design. As another suggestion in this paper, force-sensor-less impedance control is introduced which uses only position information focusing on relationship between external force and motor force. The characteristics of fractional impedance are analyzed by simulations, and lastly future topics on fractional calculus application are explained.