Fuzzy Adaptive Control for Four Wheels Steering of Construction Machinery

To shorten the steer diameter and improve maneuverability flexibility during steering, four wheels steering system of construction machinery is proposed. The steering system is constructed by mechanic-electric-hydraulic assemblies. Its construction and running principle are depicted in detail. Considering the nonlinear and time-varying uncertainty of the steering system, the controller composing of a PID controller and a fuzzy adaptive supervisory tuner is presented. The PID controller is designed to stabilize the normal system. Furthermore the upper-level supervisory tuner tunes the PID parameters to attenuate the parameter perturbation and the outside disturbance. The simulation and experiment results showed that the proposed scheme was superior to classical PID controller and can guarantee both the control performance and the robustness of the steering system.