Repetitive control of thermal shock disturbance

摘要

A control system (40) and procedure (50) that uses repetitive control to control repetitive error sources such as result from the phenomenon of thermal shock experienced by a spacecraft (10). Repetitive control is a "learning algorithm" that substantially eliminates errors in a stable control system (43) that performs highly repeatable tasks. The repetitive control system (40) and procedure (50) employs a repetitive signal generator (41) (G.sub.r), to store a sensed short-term error signal during each cycle and to process it to generate a signal that compensates for the error. The repetitive control system and procedure integrates (52) the error signal over several cycles, multiplies (53) the integrated value by a predetermined gain factor, and sums (54) it with the sensed error signal before the sensed error reaches the stable controller (43). An output filter (42), G.sub.f, which may be a multirate- sampling output filter, may be used to increase stability robustness of the repetitive control system (40) and procedure (50). The present repetitive control system (40) and procedure (50) substantially eliminates pointing error caused by thermal shock disturbance, for example. The repetitive control system (40) and procedure (50) "learns" the errors that exist in the system and over several cycles, converges on a substantially exact compensation for these errors. Implementation of the present control system (40) and procedure (50) allows the spacecraft (10) to maintain precise pointing throughout an eclipse and thereby allow the spacecraft (10) to perform its mission despite the presence of thermal shock disturbances or errors caused by other repetitive error sources.