Digital Control System Development for Optical Mirror Figure Control

Abstract : The maintenance of accurate primary mirror figure in the face of environmental disturbances is the key to the achievement of diffraction-limited performance in a large space telescope. In order to develop the concepts of optical mirror figure control, an experimental program has been initiated at the Marshall Space Flight Center, Huntsville, Alabama. A major component in this experiment will be an XDS Sigma 5-2 multi-digital computer system which will realize the mirror figure control algorithm. Development of the control system for the experimental active mirror was initially described in two earlier MIT/DL reports in this series. This report extends the previous work in several areas. Figure control laws, suitable for digital computer implementation, have been designed and incorporated in a very flexible software package. A figure control system simulation capability was achieved by including models of the figure sensor, figure actuators, mirror structure and a simulation control module in the software package. This permits the figure sensor control software to be completely checked out and evaluated using the simulation before interface with the actual hardware components is attempted.