Voltage control of a class of underactuated electromechanical systems via an energy shaping approach

Abstract

The control of a class of electromechanical systems electrically-driven by brushed Direct Current (DC) motors of permanent magnet is addressed in this paper. An energy shaping approach is used for the voltage controller design, which achieves position/speed regulation of underactuated mechanical systems –those systems with more actuators than degrees of freedom– actuated by DC motors. The main contribution is a control law in terms of voltage feeding each DC motor instead of a torque/force input, which does not need voltage or armature current feedback, but only position measurements and speed. The proposed voltage controller is useful for this class of electrically-driven mechanical systems used in experimental workbenches found in numerous automatic control laboratories. The effectiveness of the proposed controller is demonstrated through two underactuated mechanical systems: the disk-on-disk and the self-balancing robot. For the disk-on-disk system, numerical simulations are provided, whereas for the self-balancing robot, real-time experimental results are displayed.