PID自动调谐控制器-毕业外文翻译.doc

Development and Evaluation of a PID Auto-Tuning Controller Abstract：This paper presents comparative studies regarding arecently developed extension of the widely used relay-feedback PID auto-tuner. The proposed method consists of two steps:process identification and controller design. First, a non-iterative procedure is suggested for identification of two points on the process Nyquist curve .A second-order-plus-dead-time model is obtained and then used for PID controller design based on the internal model principle (IMC). For the identification of the two points on the Nyquist curve a pure relay in the feedback loop (as used in standard auto-tuning) and a relay which operates on the integral of the error are used. The paper compares the performance of autotuning methods with experimental studies on a commercial auto-tuning PID controller - a Shimaden PID autotuner. Keywords: auto-tuning, PID controller, relay experiment, Nyquist plot, commercial PID controllers. I. INTRODUCTION At the beginning of the new millennium the PID controller continues to be a key component of industrial control. Their popularity is justified by the following advantages: they have a simple structure, their principle is well understood by instrumentation engineers and their control capabilities have proven to be adequate for most control loops. Moreover, due to process uncertainties, a more sophisticated control scheme is not necessarily more efficient in real-life applications than a well-tuned PID controller. However, it is common that PID controllers are poorly tuned in practice because the choice of controller parameters requires professional – specialized knowledge by the user. To simplify this task and to reduce the tuning-time (process starting up period), PID controllers can incorporate auto-tuning capabilities. The auto-tuners are equipped with a mechanism capable of computing the correct parameters automatically when the regulator is connected to the field [Astr?m, et al., 1984; A