State Space Design of Self-Tuning Control with Reference Signal Tracking

The problem of state space design of self-tuning control systems with reference signal tracking is considered. In earlier work on state space pole-placement design, the control law specification could not eliminate the steady state error, even for simple cases like a step input or sinusoidal input. Moreover, the value of the "offset" varies as the pole locations are changed. In this paper, a modified control law, which is based on the idea of placing the zeros of the error transfer function, is utilized for complete elimination of the steady-state error for any arbitrary reference signal. On-line design is carried out by first identifying the individual reference signal. It is proposed to use the recursive prediction error (RPE) method for Joint state and parameter estimation of the process innovations model. One can then design a controller that will place the poles of the closed-loop system at specified locations in addition to placing the zeros of error transfer function to cancel the poles of the reference input. Results of simulation demonstrate the tracking properties of a controller based on this approach.