Optimal H∞ controller on the adjustment of the steering angles of a two-track 4WD autonomous vehicle

The precise control of actuators has been a major concern for control designers, especially for vehicular technology, which involves safety and the minimum error can cause hazardous consequences to human lives. This work presents the preliminary study of the control strategy for the steering system for the AGRIBOT project consist of a wheeled autonomous mobile robotic in real scale endowed with the four independent steering and driven wheels (4WSD) configuration. We applied the well-known Ackerman geometry to trace the four steering angles that allow the vehicle to correctly perform a given maneuver preserving the minimum level of stability and maneuverability. Our goal is to establish a relationship between the steering input commands and the control commands to the four actuators so that it is possible to adjust the attitude of the pneumatic over the movement axis, as the trajectory change. We present the synthesis and the analysis of an optimal H
_∞
controller based on the γ-iteration algorithm to adjust the steering angles by acting over the angular position of a motor shaft which is coupled directly to the pneumatics.