FEEDFORWARD CONTROLLER-DESIGN BY EIGENVALUE ASSIGNMENT

Active feedforward control algorithms have proven to be successful in the attenuation of stationary disturbances such as single frequency, multiple frequencies, and random inputs. In feedforward control the mean square value of a measurable response quantity induced by the disturbance input is minimized by coherent ''secondary'' control inputs. The traditional design procedure is to choose the location/number of control forces and error sensors based on a physical understanding of the response of the uncontrolled and controlled systems. Thus, an analytical procedure for actuator and sensor design in feedforward controlled systems is nonexistent in contrast to feedback control where pole allocation, optimal control, etc., are extensively used. Recent analytical work has demonstrated that feedforward controlled systems have new eigenproperties. The controlled eigenvalues and eigenfunctions are only a function of the control input location and the error quantity to be minimized. Here, an eigenvalue assignment design methodology for feedforward controllers is presented, and it is based on designing an optimal error sensor such that the controlled system eigenvalues have predetermined values.