A control problem of surface-mounted PM synchronous motor with unknown exosystem

The surface-mounted PM synchronous motor is a two-input, two-output nonlinear system. Recently, the robust output regulation problem of this motor system subject to a known neutrally stable exosystem was studied. The problem came down to a global robust stabilization problem of an augmented system composed of the original plant and an internal model. In this paper, we will further study the robust output regulation problem of the motor system subject to an unknown neutrally stable exosystem. Like the case where the exosystem is known, the current problem can be solved by globally stabilizing an augmented system. But unlike the case where the exosystem is known, the augmented system takes a much more complicated form due to uncertainty in the exosystem than the case where the exosystem is known. In particular, the dynamic uncertainty in the current augmented system is not input-to-state stable. By utilizing some dynamic coordinate transformation technique, and combining some robust control and adaptive control techniques, we will solve the problem via a recursive approach.