Control of processes with dead time and input constraints using control signal shaping

Using the idea of ‘shaping the control signal’, the authors generalise the time-delay-filter-based deadbeat control for processes with dead time to a two-level control so that actuator saturation is avoided. The controller mimics experienced manual operation to provide a two-level control signal. At the first stage (level), the controller outputs a value very close to the actuator saturation bound to provide the largest acceleration and then the controller outputs a smaller value to maintain the steady-state output at the same level as the set point. The system quickly settles in a finite time, which is explicitly determined by the saturation bound and is independent of the controller and (almost) of the sampling period. The disturbance response can be freely tuned according to the desired phase or gain margin. Three examples are given to show the effectiveness of the proposed controller.