Implementation of Torque Controller for Brushless Motors on the Omni-directional Wheeled Mobile Robot

TL;DR

This paper presents a torque controller for brushless motors on an omni-directional wheeled robot, improving path accuracy and reducing the need for frequent PI gain tuning across different surface conditions.

Contribution

The study introduces a torque control approach that incorporates motor dynamics derived from energy conservation, enhancing path accuracy over traditional PI controllers.

Findings

Torque controller yields better path accuracy than PI controller.

The controller adapts to different surface friction coefficients.

Experimental results confirm improved performance across various carpets.

Abstract

The major issue for the wheeled mobile robot is the low level controller gains tuning up especially in the robot competition. The floor surface can be damaged by the robot wheels during the competition, therefore the surface coefficient can be changed over time. PI gains have to be tuned before every match along the competition. In this research, the torque controller is defined and implemented in order to solve this problem. Torque controller consists of a PI controller for the robot wheel's angular velocity and a dynamic equation of brushless motor. The motor dynamics can be derived from the energy conservation law. Three different carpets, which have the different friction coefficients, are used in the experiments. The robot wheel's angular velocity profiles are generated from the robot kinematics with different initial conditions. The output paths of the robot with the torque controller are compared with the output paths of the robot with regular PI controller when the same wheel angular velocity profiles are applied. The results show that the torque controller can provide a better robot path than the normal PI controller.