Applications of hysteresis switching in parameter adaptive control

The authors demonstrate the usefulness of hysteresis switching in a broader context than previously considered. This is done by applying the switching algorithm to a number of specially structured families of identifier-based parameterized controllers of both the direct and indirect control types. Application to the former results in a model reference adaptive controller capable of stabilizing, without the persistent excitation, any single input, single output (SISO) process which can be modeled by a minimum-phase linear system whose transfer function has relative and McMillam degrees not exceeding prescribed integers m and n respectively. It is shown that such processes can also be adaptively stabilized with indirect adaptive controllers and hysteresis switching. An example is used to illustrate how hysteresis switching might be applied to implicitly tuned parameterized controllers to realize an adaptive controller with capabilities which, without switching, might be impossible to achieve