Effects of a Delay-Type Directional Actuator on Feedforward Disturbance Attenuation Control System of Flexible Beam

This paper proposes a delay-type directional actuator for feedforward disturbance attenuation control of flexible beam. The frequency-dependent delay used in the existing directional actuator is replaced by a (frequency-independent) delay which is determined by a desired frequency at which the upstream propagating wave is exactly canceled out, which makes the implementation of the actuator easier. The validity of the proposed actuator is shown by examining the effects on open- and closed-loop systems based on frequency response experiments and first principle models: First, it is shown that a directional wave can be generated by the proposed actuator under a suitable condition. Secondly, by a comparison of the open-loop frequency responses from the first principle modeling and frequency response experiments, it is shown that a phase-lag in the feedback path is increased by the proposed actuator. Thirdly, based on the ideal controllers that perfectly cancels the disturbance, it is shown that the peak gains of the controller and the closed-loop system from the disturbance to the measured output and control input, are prevented by the proposed actuator.