Development of Decentralized Speed Controllers for a Differential Drive Wheel Mobile Robot

Abstract

This research presents a comprehensive mathematical model and a control-oriented model for a differential drive wheel mobile robot (DDWMR). The components and their interconnection within the robot are thoroughly modeled. The proposed mathematical models are used to analyze the characteristics of the robot. The control-oriented model is a simplified one which will be used to design speed controllers. The performance of the proposed system is evaluated through four case studies, focusing on both stand-alone motor systems and the entire DDWMR. The tracking performance is evaluated using metrics such as absolute error integration and root mean square error. Simulation results show that under ideal step command, the pole-zero cancellation PI speed controller achieves the best tracking performance, while PID controllers obtained from Matlab’s Auto-tuning App perform best for standalone motor systems. For motors in a DDWMR, the PID controller with parameters derived from the Ziegler-Nichols tuning rules provides optimal tracking performance. These simulation results show that there is no universal controller that can achieve the best performance in all situations; rather, each controller is suited to specific circumstances. Nonetheless, in all case studies, better motor speed tracking leads to improved trajectory tracking performance for the robot.

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