Fractional Order PD ^α Joint Control of Legged Robots

Abstract

This paper studies a fractional order proportional and derivative controller for a hexapod robot, having legs with three DoF and joint actuators with saturation, when walking over ground with varying properties. A simulation model is developed and the robot motion is characterized in terms of several locomotion variables. Two indices measure the walking performance based on the mean absolute density of energy per unit distance travelled and on the hip trajectory errors. A set of experiments reveal the influence of different controller tunings on the proposed indices, for different locomotion conditions.