NASA Langley Research Center has developed a point sensor and piezoelectric actuator system to actively sense and reduce vibrations in flexible structures. The system uses a directional piezoelectric actuator that couples to an underlying structure like four point forces acting normal to the structure. Four miniature accelerometers are located coincident with the piezoelectric point forces to create a matched actuator/sensor pair. This matched pair enables feedback control to be implemented using simple, robust, negative feedback that requires no knowledge of the dynamics of the structure, and can be implemented using analog electronics. When attached to a flexible structure, this active damping system can reduce vibrations in a variety of applications. Compared to other systems, this approach offers good performance with a simple and compact control system.
Many piezoelectric control approaches rely on complex digital electronics to implement model-based feedback control algorithms in order to reduce structural vibrations. This new device leverages a highly directional, diamond-shaped actuator with interdigitated electrodes and four miniature accelerometers at the corners to sense vibration. The diamond shape simplifies actuator coupling to the underlying structures, eliminating edge moments present in most piezoelectric actuators, and thereby enabling a matched actuator/sensor pair with the accelerometers as sensors. This matched pair greatly simplifies the control electronics; accelerometer responses are summed, integrated, amplified, and then feed back to the actuator using analog electronics. The resulting control action is equivalent to active damping, resulting in lower structural vibration. The compact design of the actuator allows it to be mounted on a surface or incorporated within, and the overall size of the actuator can be optimized to target a range of problem frequencies.
The system can be used to reduce vibration and noise in helicopters or airplanes, stabilize larger space structures, reduce noise radiation from vibrating panels in manufacturing applications, and to stabilize optical components or other sensitive machinery.