This innovation consists of an analog controller, diamond-shaped patch actuator, and point sensors (such as accelerometers). The actuator is designed to couple to the flexural response of the structure in the same manner as a group of point sensors. This results in a co-located transducer pair. The signals from all sensors are combined, filtered, and amplified within the analog controller. The resulting signal is then applied to the actuator, which generates a control force out-of-phase with the measured response. Because the transducers are co-located, the vibration control system is inherently robust to variations in properties of the underlying structure that is being controlled. This type of control system actively suppresses the vibration of a flexible structure using surface-mounted transducers without any external mechanical connections.

One of the unique features of this system is the diamond-shaped piezoelectric actuator with interdigitated electrodes. These electrodes create a highly directional actuator that can be shaped so that it couples to the response of a flexible structure in the same manner as point sensors. The control system consists of this actuator, point sensors, and analog electronics. The miniaturization of the control and power electronics onto a small circuit board is another unique feature that makes the stand-alone vibration control unit practical. The active vibration control system is smaller, lighter-weight, and is expected to outperform comparable control systems. The technology is enabled by the development of a new actuator that allows control implementation with a very compact electrical circuit.

The gain of the control system must be adjusted to maximize system performance. However, this can be automated and incorporated within the control unit. The performance of the system will ultimately depend on the size and placement of the control units. For instance, small actuators do not efficiently couple to the structural response at low frequencies (below 500 Hz in some cases). Guidance on the sizing and placement of the control units can be provided.

This work was done by Noah Schiller, Randolph Cabell, and Daniel Perey of Langley Research Center. LAR-18034-1

Motion Control & Automation Technology Magazine

This article first appeared in the August, 2014 issue of Motion Control & Automation Technology Magazine.

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