Encoder-based path tracking with adaptive cascaded control for a three omni-wheel robot

In mobile robotics, there are already various highly manoeuvrable structures that, in order to be exploited to their full capacity, require specially designed control systems. Often, the sensing elements available for these structures are either limited or costly. The former is the case in odometry, where information is scarce and needs corroboration with other measurement methods. To overcome this limitation, we propose an adaptive cascaded control scheme for position control of the robot. In this paper, we use three encoders mounted on the each motor shaft to control the path of a three omni-wheel robot. The encoder data is then used to estimate motor speed and to ultimately close the loops of the cascaded structure: one for motor speed and one for robot position. We performed the testing and validation of the solution by using an opto-electronic motion capture system as a fixed external observer. Overall, the results are very good and look promising for future development of the mobile robotic platform.