Adaptive error correction control system for optimizing mirror

Abstract

An adaptive control includes a digital error correction system (DECS) to reduce control system error to near zero by anticipating a problem and feeding forward in time a correction to deal with the problem before it happens. The adaptive control is used in a controlled system of the kind which is cyclical in operation and which operates in response to repetitive cycle commands so that the operation of the system is substantially predictable for a significant number of cycles of operation. The adaptive control is incorporated in a spatial chopping or scanning telescope system of the kind in which a telescope mirror is moved in repetitive cycle motions and in a rigidly prescribed pattern between varied orientations and wherein the mirror is held for a prescribed, relatively long period of time in each orientation and is moved rapidly in a relatively short period of time from one orientation to another. The adaptive control permits accurate control of the command waveform frequency and shape, enables the telescope system to keep position error near zero by using, in combination with the feedback loop, a feed forward loop directly driving the actuators during the transition period and actively holding the mirror in position during the dwell periods. The adaptive control provides the ability to eliminate overshoot and ringing, because the force command provides the precise amount of braking required to exactly stop the mirror motion.