Design of H/sub 2/ and H/sub /spl infin// controllers with two degrees of freedom

• Main Authors: Christen, U., Weilenmann, M.F., Geering, H.P.
• Format: Conference Proceeding
• Language: English
• Subjects: Control systems; Design methodology; Filters; Hydrogen; Motion control; Noise shaping; Regulators; Rotors; Tail; Transfer functions
• DOI: 10.1109/ACC.1994.734987

The tracking behavior of many feedback control systems can be improved by using a compensator with two degrees of freedom which processes the reference signal independently of the plant output signal, e.g., the reference signal can be processed by a static prefilter. This is described in the first part of this paper dealing with LQG/LTR and H/sub 2/ controllers. With H/sub /spl infin// methods, it is easy to design more sophisticated, dynamic feedforward controllers. They can be developed either in a second step, when the loop is already closed by a feedback compensator, or in one step together with the H/sub /spl infin// feedback part of the compensator. This latter possibility has the advantage that only one observer is needed for the two parts of the controller, thus the number of states of the complete compensator is minimized. An application of these design configurations to a helicopter is shown. Step responses without overshoot are achieved for position control.