Synthesis and implementation of sensor-less active shunt controllers for electromagnetically actuated systems

Electromagnetic transducers have been used extensively for active feedback control of mechanical vibration. In this paper, to reduce vibration, we demonstrate a new technique where an electrical impedance is connected to the terminals of an electromagnetic transducer. By measuring the coil terminal voltage and applying a related current, or vice-versa, vibration in the mechanical host system can be controlled. The task of impedance design is cast as a standard multi-input-multi-output (MIMO) control problem to facilitate synthesis by standard methods such as linear quadratic regulator (LQR) or H-2. Potential applications include: vehicle suspension systems, vibration isolation platforms, and the control of enclosed-sound fields. Active admittance or impedance controllers require no external sensors. The presented techniques are verified experimentally through the application to a single-degree-of-freedom (DOF) system.