An Adaptive Internal Model Controller

A modified internal model control scheme is introduced, which can significantly improve response to disturbance changes. It is applicable to open loop unstable systems, but not to systems with zeroes outside the unit circle. An adaptive controller is then designed, which uses a "standard" internal model control law when the parameter estimates are poor, but switches to the new control scheme when the estimates improve. Simulations show that this adaptive controller handles well both set point and disturbance changes.