Modular disturbance observer based constrained PI-controller design

The paper deals with modular design of constrained disturbance observer (DO) based PI control with different filtering properties. After treating possible effects of control constraints completing deeper analysis of the core structure of the P controller with different types of additional dynamics approximations [1], it will be expanded by considering structures of constrained PI₁ controllers, in which the integral action is introduced as the DO based load (input disturbance) reconstruction and compensation using inversion of the plant dynamics. In the nominal case, for suppressing measurement and quantization noise different DO filters may be used without necessity to repeat for the new structure analysis of the optimal and critical P controller tuning. So, by simple means, open and flexible approach offering reasonably better performance than the traditional PI control is achieved. Thereby, the loop performance is evaluated by measuring deviations from strictly monotonic (MO) and one-pulse (1P) transients typical for plants with dominant first order dynamics [1], as illustrated by example of speed servo control using incremental encoder.