Adaptive control for nonlinear systems with time-varying control gain

We propose a scheme for nonlinear plants with time-varying control gain and time-varying plant coefficients,on the basis of a plant model consisting of a brunovsky-type model with polynomials as approximators. we develop an adaptive robust control scheme for this plant,under the following assumptions: (i) the plant terms involve time-varying but bounded coefficients,being its upper bound unknown; (ii) the control gain is unknown,not necessarily bounded,and only its signum is known. to achieve robustness,we use a combination of robustifying control inputs and dead zone-type update laws. we apply this methodology to the speed control of a permanent magnet synchronous motor (pmsm),and we achieve proper tracking results. copyright © 2012 alejandro rincon and fabiola angulo.