This paper describes the computer-aided design of suitable control strategies for parallel linkage steering of an experimental automated guided vehicle. The microprocessor-based steering control system is modeled, and stability characteristics using proportional control are investigated via describing functions. Although the approximation is coarse, the analysis indicates the upper bound for gain and suggests derivative action for improved control. For better accuracy, a flexible and fast

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... tion program is developed that makes possible an efficient search for "optimal" control laws for operation of the vehicle under the constant speed mode and the slow-down mode. Time-independent control laws are investigated, and solutions are found that give tolerable tracking over 90-deg arcs of 0.5-m radius. The simulation results show that timedependent control laws are essential for improved, nonoscillatory tracking.