Self-sensing actuators for precision structures

Piezoceramic materials provide a practical way to implement structural control systems needed on precision spacecraft such as remote sensing satellites and sensitive astronomical platforms. Perhaps the most attractive feature of these materials is their capacity to function simultaneously as actuator and sensor. This makes possible self-sensing actuators (SSAs) in which a single electromechanical device serves as both sensor and actuator. Self-sensing actuation has been developed to a promising level of maturity in laboratory studies; however some issues remain to be resolved before SSAs can be used confidently on space systems. The sensitivity and dynamic range of SSAs are limited by noise and nonlinearities in the associated circuitry. Variations of circuit component parameters and of piezoelectric and dielectric properties also affect SSA performance. One challenge is to design circuits which can exploit the mechanical and electrical properties of piezoceramic materials in the space environment. Another challenge is to accurately and practically model SSAs to account for interactions with the structure and circuit elements. This paper explores the needs of spacecraft requiring high levels of dynamic precision, how self-sensing actuators might meet them, and identifies development needs.