A new algorithm for multirate digital control law synthesis

A novel algorithm for multirate digital control law synthesis is presented. The algorithm accommodates a generalized controller structure, and all sampling rates for sensor sample-and-hold circuits, digital processor circuits, and control sample-and-hold circuits can be chosen independently. The algorithm uses a gradient-type numerical search to determine the controller matrices so that a finite-time, linear, quadratic, cost function is minimized. The finite time avoids problems with destabilizing sets of controller matrices. To speed the numerical search, closed-form expressions are used to calculate the cost and gradient of the cost with respect to the controller matrices exactly