Discrete time servomechanisms for an optical telescope

Describes the design study carried out for the servosystems for the 2.5 m Nordic Optical Telescope to be erected on La Palma in the Canary Islands. The servosystems are for the two main movements of the telescope: the azimuth-movement about a vertical axis; and the altitude-movement about a horizontal axis. A discrete-time state-variable feedback controller was designed for each of the servos. A joint state and disturbance estimator based on the system model and a linear disturbance model was added to the controller. This estimator does not only provide state estimates for the controller, but also estimates of the main disturbances