This paper provides a quantitative assessment of the performance of interdigital electrode (IDE) actuators and dampers constructed using ACX QuickPack(R) piezoelectric packaging technology. The details of the concept, device design, experimental plan and results, and analysis of the IDE devices are presented. Electromechanical coupling coefficients calculated using two different methods indicated values of 0.45 to 0.71 were achieved for IDE devices, as compared to 0.29 to 0.35 for conventional d(31) devices. Experimental results are provided that compare the damping and actuation performance of conventional d(31) devices with the performance of IDE devices, Resistively shunted IDE damper devices achieved greater than a factor of two in improvement in added damping over conventional PZT dampers. In addition, the high field generative strain of IDE actuators was shown to be 70% greater than that produced by a d(31) actuator.

This paper addressed the feasibility of using an active piezoelectric buffet suppression system to reduce buffet vibrations in vertical tail aircraft. During the assessment, functional requirements were defined, models were developed, and full-scale piezoelectric buffet suppression systems were designed and evaluated. A variety of actuator distributions, sensor locations and controller architectures were examined and it was found that significant performance improvements could be achieved (greater than 70 percent) with minimal weight penalties (less than 8 percent). This work enabled the evaluation of issues such as system performance versus added weight and piezoelectric actuator control authority and power requirements. The study showed that the added performance benefit (in terms of vibration reduction and fatigue life) are far greater than the weight penalty, and that piezoelectric actuators have the control authority required to suppress high energy buffet forces within aircraft geometry, weight, and power constraints. Further, the high performance achieved (much greater than that defined in the functional requirements) suggests that systems can be designed with a much lower weight penalty (1/2 to 1/4) than that assumed in this study.

Results are presented of on-going closed-loop ground experiments on the MACE test article, the objective of which is to investigate the extent to which closed-loop behavior of flexible spacecraft in zero gravity can be predicted, as well as to examine orbit system identification and control reconfiguration. The MACE hardware consists of three torque wheels, a two-axis gimballing payload, inertial sensors, and a flexible support structure. With the acquisition of a second payload, this is to represent a multiple payload platform with significant structural flexibility. When linear quadratic Gaussian control is used, payload pointing accuracy is improved by an order of magnitude when disturbed by a broadband torque disturbance. The successes and failures of the design and implementation process are discussed.