Imposing Constraints in a Full State Feedback System Using Multithreaded Controller

The article proposes a ground-breaking solution to address the challenge of imposing constraints in a full state feedback (FSF) control system. Its simplicity is comparable to the introduction of saturation blocks in the cascaded control system. In the developed control system, a given state variable is stabilized at the threshold value using a separate FSF controller. The overall controller consists then of a set of controllers, the main one with an external reference signal and auxiliary controllers with the internal references set to the desired limits to be imposed on each of the physical states of the investigated plant, operating in parallel fashion (hence the proposed name-multithreaded). This means that in each time instance, the processor executes all FSF controllers. Additionally, if the auxiliary integral states are implemented, a back-calculation algorithm is employed to keep the auxiliary states at the desired level for the controllers that are idling at a given time instance. The median of the calculated control signals is put through to the plant as a control signal. Such an elegant and straightforward way of handling constraints in the state feedback system has never been reported before and is currently patent pending. The proposed method is validated for a servo drive using hardware-in-the-loop setup. All the obtained results confirm technical feasibility of the controller structure and its ability to keep all the state variables within the required intervals.