ABSTRACT
This chapter discusses the selection of sampling rate for a digital control system. Computer cost also increases because less time is available to process the controller equations. Reducing the sample rate for the sake of reducing cost, however, may degrade system performance or even cause instability. Aside from cost, the selection of sampling rate for digital control systems depends on many factors, including smoothness of the time response, effects of disturbances and sensor noise, parameter variations and quantization. Samplingis the process of deriving a discrete-time sequence from a continuous-time function. The main objective of many digital control system designs is to select a controller so that the system-tracking output, tracks or “follows” the tracking command input. An interesting problem involving the sample rate selection is encountered in the control system design of flexible spacecraft. In general, when the controller is implemented digitally, it will perform less well than the analog controller in the face of white noise disturbance inputs.
