Dynamics and Control of Four Wheeled Differentially Steered UGVs

Autonomous navigation of ground vehicles is a growing research area. Skid steered wheeled ground vehicles are of interest because of the system’s relatively easy control parameters. Steered wheels require actuation and control for the steering and speed of the steered wheels while skid steering just requires actuation and control of the wheel speeds, usually just a left and right wheel speed. Four Wheeled differentially steered vehicles are built primarily for straight line motion since the instantaneous centers of zero velocities for the four wheels are always at infinity when there is no sliding in the wheels. When the vehicle has to negotiate a corner, it uses the differential velocities between sides to force the wheels to slide and perform the cornering maneuver. Maneuvering is difficult when the ground friction is very high because of undue stresses in the axle structure. This paper analyses the dynamics of such vehicles that relates the traction and skid friction forces and proposes a suitable control system. At this time, the paper is supported by simulation results while experimental work is still going on.