Restricted structure adaptive control including series 2 DOF tracking

A new approach to adaptive control is presented based on a multiple model control calculation, where the system model is identified using extended least squares. The control law calculation is for a restricted structure controller, such as a simple PID form. The restricted structure algorithm enables a simplified cost-function to be optimized numerically. This approach can be used for systems described by multiple models, where the restricted structure controller is optimised across a set of model/cost-function pairs. If these models are obtained by a plant identification step an adaptive algorithm results. The main advantage of the approach is the cautious nature of the solution. The new update of the controller involves averaging the cost across old and new models and this provides cautious robust adaptive control action. The solution also provides a degree of robustness that can be predefined, assuming the possible plant models are all within a given set