POLE PLACEMENT DIRECT ADAPTIVE-CONTROL FOR TIME-VARYING ILL-MODELED PLANTS

This note addresses the problem of preserving stability of pole placement direct adaptive control in spite of output bounded disturbances, time-varying plant model parameters, and unmodeled dynamics, assumed to be small in the mean. The controller parameter estimates are shown to track, in the mean, their true (time-varying) parameter values. Such a convergence property is achieved using an ad hoc, internally generated, excitation sequence which ensures persistent excitation. Furthermore, in the ideal case the convergence of the parameter estimates is exponential, avoiding, in particular, possible chaotic phenomena. © 1990 IEEE