【正文】 限制不可缺少的偏差被計(jì)算的時(shí)間段。在有幾分鐘響應(yīng)時(shí)間的環(huán)、數(shù)學(xué)環(huán)路調(diào)諧中被推薦，因?yàn)榉磸?fù)試驗(yàn)要花費(fèi)數(shù)天，而僅僅是為了找到一套穩(wěn)定的環(huán)價(jià)值。 發(fā)明。增加 P 值 直到環(huán)的輸出值擺動(dòng)，然后， P 值 應(yīng)該大約被設(shè)為標(biāo)準(zhǔn)值的四分之一。 軟件工具 一致的協(xié)調(diào)。手工協(xié)調(diào)方法相對(duì)來說可能沒有效率。 最佳控制行為就是過程能根據(jù)應(yīng)用作出相應(yīng)的變化。 摘要 三種參數(shù)控制的輸出值，比例，積分和微分綜合起來能夠計(jì)算出 PID 調(diào)節(jié)器的輸出，計(jì)算控制器輸出時(shí)， PID 算法的最終形式 u(t)為： 協(xié)調(diào)參數(shù)分別是： Kp:比例增益 — 偏差愈大時(shí)， Kp 也愈大，比例期補(bǔ)償更大。對(duì)總的控制作用的積分大小由積分時(shí)間常數(shù)來決定，即 Ki，積分值計(jì)算如下： 圖 變化時(shí)的反應(yīng)曲線 Iout：積分值 Ki:積分時(shí)間常數(shù)，協(xié)調(diào)參數(shù) e:偏差 =SPPV ζ：積分時(shí)間 積分值加速面向設(shè)定值的過程運(yùn)動(dòng)并且消除殘余的只與控制器發(fā)生作用的穩(wěn)態(tài)偏差。 e:偏差 =SPPV t:時(shí)間或瞬時(shí)時(shí)間（當(dāng)前的） 圖 2. Kp 改變后的變化曲線 一個(gè)高的比例增益產(chǎn)生于一種輸出值的大的變化。 由于它們悠久的歷史，簡(jiǎn)易，良好的理論基礎(chǔ)以及簡(jiǎn)單的設(shè)置、維護(hù)要求， PID 控制器被許多應(yīng)用實(shí)踐所采納。人不會(huì)這樣做，因?yàn)槲覀兪怯兄腔鄣目刂迫藛T，可以從歷史經(jīng)驗(yàn)中學(xué)習(xí)，但 PID 控 制器沒有學(xué)習(xí)能力，必須正確的設(shè)定。測(cè)量值與給定值之間的差就是偏差值，太高、太低或正常。 15 圖 1. PID 控制器框圖 注釋：由于控制理論和應(yīng)用領(lǐng)域的差異，很多相關(guān)變量的命名約定是常用的。根據(jù)具體的工藝要求，通過 PID 控制器的參數(shù)整定，從而提供調(diào)節(jié)作用。t work when the process is starting up from noload. This section describes some traditional manual methods for loop tuning. There are several methods for tuning a PID loop. The most effective methods generally involve the development of some form of process model, then choosing P, I, and D based on the dynamic model parameters. Manual tuning methods can be relatively inefficient. The choice of method will depend largely on whether or not the loop can be taken offline for tuning, and the response time of the system. If the system can be taken offline, the best tuning method often involves subjecting the system to a step change in input, measuring the output as a function of time, and using this response to determine the control parameters. Choosing a Tuning Method 8 MethodAdvantagesDisadvantages Manual TuningNo math required. Online experienced personnel. Ziegler–NicholsProven Method. Online upset, some trialanderror, very aggressive tuning. Software ToolsConsistent tuning. Online or offline method. May include valve and sensor analysis. Allow simulation before cost and training involved. CohenCoonGood process math. Offline method. Only good for firstorder processes. Manual tuning If the system must remain online, one tuning method is to first set the I and D values to zero. Increase the P until the output of the loop oscillates, then the P should be left set to be approximately half of that value for a quarter amplitude decay type response. Then increase D until any offset is correct in sufficient time for the process. However, too much D will cause instability. Finally, increase I, if required, until the loop is acceptably quick to reach its reference after a load disturbance. However, too much I will cause excessive response and overshoot. A fast PID loop tuning usually overshoots slightly to reach the setpoint more quickly。 however, some systems cannot accept overshoot, in which case an overdamped closedloop system is required, which will require a P setting significantly less than half that of the P setting causing oscillation. Effects of increasing parameters Parameter Rise Time shootSettling Time . Error Kp Decrease Increase Small Change Decrease Ki Decrease Increase Increase Eliminate Kd Small Decrease Decrease Decrease None –Nichols method Another tuning method is formally known as the Ziegler–Nichols method, introduced by John G. Ziegler and Nathaniel B. Nichols. As in the method above, the I and D gains are first set to zero. The P gain is increased until it reaches the critical gain Kc at which the output of the 9 loop starts to oscillate. Kc and the oscillation period Pc are used to set the gains as shown: Ziegler–Nichols method Control Type Kp Ki Kd P Kc PI Kp /Pc PID Kc 2Kp / Pc KpPc / 8 PID tuning software Most modern industrial facilities no longer tune loops using the manual calculation methods shown above. Instead, PID tuning and loop optimization software are used to ensure consistent results. These software packages will gather the data, develop process models, and suggest optimal tuning. Some software packages can even develop tuning by gathering data from reference changes. Mathematical PID loop tuning induces an impulse in the system, and then uses the controlled system39?？刂破鞯捻憫?yīng)可以被認(rèn)為是對(duì)系統(tǒng)偏差的響應(yīng)。 1． 控制環(huán)基礎(chǔ) 一個(gè)關(guān)于控制環(huán)類似的例子就是保持水在理想溫度，涉及到兩個(gè)過程，冷、熱水的混合。作為一個(gè)控制器，在確定溫度給定 值后，就可以粗略決定改變閥門位置多少，以及怎樣改變偏差值。為有效的控制系統(tǒng)選擇正確的參數(shù)被稱為整定控制器。 控制器理論 16 注釋：這部分描述 PID 控制器理想平行或非相互作用的形式。如果比例增益太高，系統(tǒng)將變得不穩(wěn)定。然而，因?yàn)榉e分從過去的積累誤差作出反應(yīng)，引起當(dāng)前的值越過設(shè)定值（跨過設(shè)定值向其它方向改變）。過大的比例增益會(huì)導(dǎo)致系統(tǒng)的不穩(wěn)定乃至崩潰。一些過程不允許在設(shè)定值以外易變的過程超限，如果發(fā)生了，將是不安全的。 方法的選擇基本依賴于控制環(huán)是否可以協(xié)調(diào)，以及系統(tǒng)的響應(yīng)時(shí)間。在線或脫機(jī)的方法。 然后增加 D 直到過程補(bǔ)償在足夠的時(shí)間內(nèi)是正確的。如同在上面的方法內(nèi)， I 和 D 常數(shù)開始時(shí)先被置零。 而最佳的控制值更難以發(fā)現(xiàn)。 避免不可缺少的時(shí)間段高于或低于預(yù)設(shè)值。 整定函數(shù)，知道 PV 已經(jīng)進(jìn)入可控制的區(qū)域。 數(shù)學(xué) PID 環(huán)路調(diào)節(jié)在系統(tǒng)里引起一個(gè)推動(dòng)，然后根據(jù)被控制的系統(tǒng)的頻率響應(yīng)設(shè)計(jì) PID 環(huán)標(biāo)準(zhǔn)值。 和 納撒尼爾 手工調(diào)節(jié) 如果系統(tǒng)必須保持在線，一種協(xié)調(diào)方法把積分 和微分時(shí)間常數(shù)置 零。 過程干擾，一些反復(fù)試驗(yàn)，非常良好的協(xié)調(diào)。最有效的方法一般與某種形式的過程模型的發(fā)展有關(guān)，然后選擇的 P,I 和基于動(dòng)態(tài)模型參數(shù)的 D?？刂骗h(huán)的協(xié)調(diào)根據(jù)那些期望控制過程的最佳值來調(diào)整它的控制參數(shù)。但是，信號(hào)噪音對(duì)偏差值非常敏感，而且如果噪音和微分度足夠大的話，將使系統(tǒng)變得不穩(wěn)定。積累的誤差通過積分調(diào)節(jié)后再作用于輸出。 比例度計(jì)算如下： Pout:比例度 Kp：比例系數(shù)，協(xié)調(diào)參數(shù)。汽車游覽控制就是一個(gè)自 動(dòng)化的過程控制的例子。輸出值將在期望值或一常量周圍擺動(dòng)，甚至破壞系統(tǒng)穩(wěn)定性。控制器的輸出對(duì)象和過程的輸入對(duì)象稱為控制參數(shù)。積分作用的缺乏可以防止系統(tǒng)根據(jù)控制目標(biāo)而達(dá)到它的目標(biāo)值。這三種控 制的結(jié)合可用來調(diào)節(jié)過程系統(tǒng)，例如調(diào)節(jié)閥的位置，或者加熱系統(tǒng)的電源調(diào)節(jié)。s shower water at the ideal temperature, which typically involves the mixing of two process streams, cold and hot water. The person feels the water to estimate its temperature. Based on this measurement they perform a control action: use the cold water tap to adjust the process. The person would repeat this inputoutput control loop, adjusting the hot water flow until the process temperature stabilized at the desired value. Feeling the water temperature is taking a measurement of the process value or process variable (PV). The desired temperature is called the setpoint (SP). The output from the controller and input to the process (the tap position) is called the manipulated