AAS 95-320

Actuator/Sensor Placement Using Degree of Controllability and Observability for Digitally Controlled Orbiting Platforms

A. J. Ericsson, P. M. Bainum and G. Xing, Howard University, Washington, D.C.

Abstract

In this paper some definitions of degree of controllability/observability, which are based on the scalar measurement of the controllability/observability Grammian matrix, are presented for discrete-time systems. These definitions are applied to the actuator/sensor placement problem for thin flexible orbiting square platforms. For several typical systems, the LQG transient time responses along with the degrees of controllability and observability are presented. For this investigation several possible arrangements for actuator/sensor placement are considered. The maximum order of the open-loop state vector is selected to be 18 (describing 3 rigid rotational motions plus 6 flexible transverse modes). With this background six different systems are analyzed. These systems allow for comparisons in the number of states in the model, as well as, in the number of actuators/sensors in the system.