Discrete modified Smith predictor based on optimal control method for a plant with an integrator

Abstract

In this paper, a discrete modified Smith predictor based on optimal control design method is proposed. A plant with long dead-time is controlled by means of a predicted-state feedback technique and a modified Smith predictor composed of a plant predictor and an observer. In this method, states of a plant are obtained by an observer because the states are not measured directly in practice. The advantages of the proposed method are that a steady-state error caused by a disturbance can be eliminated and that an unstable plant can be made stable unlike conventional methods such as Smith predictor and Internal Model Control. It also achieves good robustness to modeling errors by adjusting weights of LQI-scheme. In simulation studies, it is shown that the proposed method is effective for these plants. Furthermore, by applying the proposed method to a pneumatic actuator, the effectiveness of the method is confirmed.

Positioning Control System Based on ZPETC and Optimal Control Method for Plant with Dead-Time

“…Astrom et al [4] has proposed method wherein a plant with dead-time is controlled by a predicted-state feedback technique and a modified Smith predictor [5] composed of a predictor and an observer. Ono et al [6] proposed a control method by using a new Smith predictor, which removes the effect of dead-time from a closed-loop system. Disturbance observer based on observer can remove effect of disturbance and modeling error from a system.…”

A Discrete PID Control System Using Predictors and an Observer for the Influence of a Time Delay

“…However, for plants with integrators, both IMC and the Smith predictor induce a steady state error due to an input-side disturbance; this is serious problem. The approaches used to solve this problem include the modified IMC [3], the modified Smith predictor that use a predictor of the controlled plant [4] [5], the method of connecting a PID controller predictor and a model of the controlled plant to the conventional PID control system (PID control with time delay compensation). [6] These are effective methods for reducing the influence of the time delay on the disturbance response.…”

Improving Digital Control System Performance Through a Novel Jitter Compensating Method

“…The author suggests to incorporate any constant time delay between input sampling and the response of the plant in the process (plant) model, when designing the controller. The solution is equally applicable in the design of plant dead-time compensators [43]. The solution considers a continuous time control system described by (3.1),…”