An Investigation of Different Control Schemes of an H-Bridge Converter for a Wheeled Mobile Robot

One of the most intriguing recent scientific study subjects with a wide range of applications is mobile robots. As a branch of mobile robot, wheeled mobile robot has been an attractive topic recently due to its simple mechanism and motion flexible features. Because of the robot mobility, onboard power sources such as battery, fuel cell, photovoltaic, or super capacitor are used. As a consequence, direct current motors are utilized as actuators. Obviously, a DC motor requires a driver to adjust its output power to the required load power, which is often variable based on the working environment and user directives. Although dual H-bridge DC motor drivers are commonly available, their control strategies and how they affect the performance of mobile robot systems have not been thoroughly addressed. In this work, different control schemes of H-bridge converters are analyzed. Corresponding mathematical model of H-bridge converters are proposed and utilized in design the controller for a wheeled mobile robot. The whole system is modelled and simulated in Matlab/Simulink. Effectiveness of different control schemes of an H-bridge converter on the performance of a wheeled mobile robot are investigated. Simulation results indicated that with bipolar switching scheme, the motor has highest current and torque ripple and hence the robot has highest speed ripple. With the unipolar switching scheme, the system achieves lowest current-, torque-, and speed-ripple. However, this type of switching scheme requires higher control effort. As a compromise between output performance and control efforts, low- and high-frequency switching scheme is recommended for mobile robot system.