Estimation of DC motor parameters using a simple CMOS camera

Different components of control systems for mobile robots are based on dynamic models. In low-cost solutions such a robot is wheeled and equipped with DC motors, which have to be included in the model of the robot. The model is fairly simple but determination of its parameters needs not to be easy. For instance, DC motor parameters are typically identified indirectly using suitable measurements, concerning engine voltage, current, and rotation speed under various conditions. The paper describes a method of estimating the DC motor parameters of a mobile robot using a simple CMOS camera. A color marker is attached to the robot platform, which indicates the position of the robot in the taken video images. Step excitation of the voltage input of the engine is applied, and estimation of robot's movement parameters is next performed by image processing. Then the response of the identified model is adjusted to the measured step response using Matlab functions, based on least squares. In this experiment the available maximum camera framerate appeared to be too low to record the robot movement properly. This obstacle is overcome by using the utility of CMOS cameras concerning the possibility of trading-off framerate to resolution.