Track-following controller for an acoustically excited double-paddle scanner

This paper presents preliminary results on the experimental application of a track-following control to an acoustically actuated micro-scanning mirror. Scanning mirrors demand high degree of precision in keeping constant the scanner operational frequency and amplitude of oscillation. This can hardly be achieved by using only open-loop strategies, since these micro devices are very sensitive to environmental conditions, which could cause changes in their natural frequencies. In order to maintain constant the operating frequency and amplitude, a closed-loop control strategy is proposed. The outline of this strategy is that the angular velocity of the scanning mirror must follow a sinusoidal reference signal of predefined frequency and amplitude. This control design is based on the internal model principle. We require that the acoustically actuated micro-scanner must oscillate at 1164Hz with a peak velocity of 0.08 m/sec. The obtained experimental results show that it was possible to control this new kind of optical scanners to the specified frequency and amplitude with small tracking error