A homogeneity-based path following shared control system for UGVs

Human-robot shared control is used to permit an unmanned ground vehicle (UGV) to semi-automatically follow a desired path. The control input from a human is blended with the input from an automatic controller using a mixed-initiative blending law. A passive measure of human intent governs the blending law, permitting a rapid and smooth transition between human- and robot-control. The robot's automatic controller is formulated using a kinematic model of the UGV, which is based on Ackermann steering. The resulting automatic control law is mathematically homogeneous. The homogeneity is used to dynamically rescale the automatic control input so that it always respects the magnitude constraints of the steering actuator. The stability of the closed-loop human-robot shared control system is proved. Illustrative simulations of the proposed control law, in which a human operator imposes steering commands on the UGV through a joystick, are presented.