بررسي رفتار ديناميكي سيستم هاي كنترلي داراي پيش بيني كننده تاخير زماني اسميت

Investigating Dynamic Behavior of Control Systems Including Time-Delay Smith Prer ictor

The problem of Time-Delay or Dead Time (DT) in control systems is an old problem which is of primary importance in process control as well. It is known as one ofthe main effects in attenu ating the performance ofcontrol systems. The firs t proposed solution for this problem was the Smith predictor in i95 7. it was based on the idea ofremoving the time-delay from the charac teristic equation ofthe control loop, which seemed to be very attractive at the first. In this paper the dynamic behavior ofthe open loop transferf unction of control systems with Smith dead-time compensator were inves tigated. The various cases resulting to limited or non-limited phase behavior were discussed. In this way the stability characteristics of such systems were discussed and revealed that it is possible to make the behavior of the closed loop system to trace the beha vior ofthe minimum phase term available in the open loop transferfunction oj the system/or improving the performance ofthe control loop .