Saturation control of a dc motor

A novel approach for implementing an active nonlinear vibration absorber is presented. The absorber takes advantage of the saturation phenomenon that occurs in autoparametric multi-DOF systems coupled with quadratic nonlinearities. The strategy is based on introducing a supplementary second-order controller that is coupled to the plant via an actuator and a nonlinear feedback control law. Once the plant is forced near resonance, its response becomes quickly saturated and the remaining oscillatory energy is channeled to the controller. We demonstrate theoretically and experimentally the application of the strategy to regulate the oscillations of a dc motor. We analyze the equations of motion and we assemble a circuit that emulates the controller equation and conduct analog simulations to investigate the technique. Finally, we perform experiments by using the circuit to suppress the vibrations of a rigid beam connected to a dc motor. Our initial investigations demonstrate that saturation control can be implemented very successfully to suppress the vibrations of resonantly excited systems. (Author)