Speed control of vibration micro-motors of a micro-robotic platform

In this paper we consider the dynamic modeling and the speed control of vibration micro-motors, under power and sensor hardware constraints due to the centimeter-scale dimensions of the motors. The micro-motors are attached on a centrifugal-force micro-robotic mobile platform. The dynamic model of the low cost motor is presented, and discussed. The experimental procedure for the motors´ parameter identification is presented, and the design of a model-based controller aiming at the control of the speed of the motors is analyzed. In addition, the practical implementation of the designed controller is discussed and experimentally evaluated. In order to measure the rotational speed of each centimeter-scale vibration motor, a rotary encoder with one count per revolution is designed and constructed. Despite this sensor hardware limitation, the experimental results indicate that the micro-motors were successfully modeled, and that the proposed controller results in the minimization of the steady-state error and in an increase of the motors´ bandwidth by a factor of three. Additional experiments showed that the application of the model-based speed controller results in a motion of the micro-robotic platform of higher precision.