【正文】 32參考文獻[1] 盧 佩，劉效勇. 溫室大棚溫濕度模糊解耦控制系統(tǒng)設計與仿真. 農(nóng)機化研究，2010（1）：4447[2] 黃力櫟，胡斌，羅昕. 溫濕度解耦模糊控制系統(tǒng)的研究. 農(nóng)機化研究，2010（2）：5659[3] 朱虹. 基于模型的溫室環(huán)境控制算法研究. 南京：東南大學，2005[4] 師黎. 智能控制實驗與綜合設計指導. 北京：清華大學出版社, 2008 [5] 張瑞華. 溫室環(huán)境自動監(jiān)控. 計算機與農(nóng)業(yè), 2002（2）：810[6] 馮冬青，謝宋和等. 模糊智能控制. 北京：化學業(yè)出版社，2003 [7] 魯燕，何曉娥，陸海燕，李萍萍. ，2004，30（3）：810[8] 張曾科. 模糊數(shù)學在自動化技術中的應用. 北京：清華大學出版社，2003[9] 鄧璐娟. 智能溫室的模型和控制策略研究. 上海：上海大學，2004[10] 楊汝清. 智能控制工程. 上海：上海交通大學出版社，2001[11] 孫優(yōu)賢. 多變量解耦控制系統(tǒng). 浙江大學學報，1980（3）：1719[12] 章衛(wèi)國，楊向忠. 模糊控制理論與應用. 西北工業(yè)大學出版社，1999[13] 王濤，王艷平等. 模糊控制系統(tǒng)的設計及穩(wěn)定性分析. 科學出版社，2004[14] 李秋紅，葉志峰，徐愛民. 自動控制原理實驗指導. 國防工業(yè)出版社，2007[15] 王沫然，陳懷坤. Simulink4建模及動態(tài)仿真. 電子工業(yè)出版社，2002[16] Mohand Mokhtari. MATLAB 與Simulink工程應用. 電子工業(yè)出版社，2002[17] 陳曉平，李長杰. MATLAB及其在電路與控制理論中的應用. 中國科學技大學出版社，2004[18] 石辛民. 模糊控制及MATLAB仿真. 北京：清華大學出版社, 2008 44外文資料翻譯Ultrasonic distance meter Document Type and Number:United States Patent 5442592 Abstract:An ultrasonic distance meter cancels out the effects of temperature and humidity variations by including a measuring unit and a reference unit. In each of the units, a repetitive series of pulses is generated, each having a repetition rate directly related to the respective distance between an electroacoustic transmitter and an electroacoustic receiver. The pulse trains are provided to respective counters, and the ratio of the counter outputs is utilized to determine the distance being measured. Publication Date:08/15/1995 Primary Examiner:Lobo, Ian J. OF THE INVENTION This invention relates to apparatus for the measurement of distance and, more particularly, to such apparatus which transmits ultrasonic waves between two points. Precision machine tools must be calibrated. In the past, this has been acplished utilizing mechanical devices such as calipers, micrometers, and the like. However, the use of such devices does not readily lend itself to automation techniques. It is known that the distance between two points can be determined by measuring the propagation time of a wave travelling between those two points. One such type of wave is an ultrasonic, or acoustic, wave. When an ultrasonic wave travels between two points, the distance between the two points can be measured by multiplying the transit time of the wave by the wave velocity in the medium separating the two points. It is therefore an object of the present invention to provide apparatus utilizing ultrasonic waves to accurately measure the distance between two points. When the medium between the two points whose spacing is being measured is air, the sound velocity is dependent upon the temperature and humidity of the air. It is therefore a further object of the,present invention to provide apparatus of the type described which is independent of temperature and humidity variations. OF THE INVENTION The foregoing and additional objects are attained in accordance with the principles of this invention by providing distance measuring apparatus which includes a reference unit and a measuring unit. The reference and measuring units are the same and each includes an electroacoustic transmitter and an electroacoustic receiver. The spacing between the transmitter and the receiver of the reference unit is a fixed reference distance, whereas the spacing between the transmitter and receiver of the measuring unit is the distance to be measured. In each of the units, the transmitter and receiver are coupled by a feedback loop which causes the transmitter to generate an acoustic pulse which is received by the receiver and converted into an electrical pulse which is then fed back to the transmitter, so that a repetitive series of pulses results. The repetition rate of the pulses is inversely related to the distance between the transmitter and the receiver. In each of the units, the pulses are provided to a counter. Since the reference distance is known, the ratio of the counter outputs is utilized to determine the desired distance to be measured. Since both counts are identically influenced by temperature and humidity variations, by taking the ratio of the counts, the resultant measurement bees insensitive to such variations. DESCRIPTION of ultrasonic distance measurement 1, the principle of piezoelectric ultrasonic generator Piezoelectric ultrasonic generator is the use of piezoelectric crystal resonators to work. Ultrasonic generator, the internal structure as shown in Figure 1, it has two piezoelectric chip and a resonance plate. When it39。 仿真結果分析 經(jīng)過多次參數(shù)修改與系統(tǒng)調(diào)試，得到最終的仿真結果如圖55所示：圖55 系統(tǒng)仿真結果圖結果表明，溫室內(nèi)的溫度和濕度存在相互的影響，當沒有進行控制時當溫度升高時，濕度就會有所下降，溫度下降時濕度又會有所上升，同樣溫室濕度發(fā)生浮動時，溫度也會發(fā)生變化，并且是逆向的變化。此時就可以打開模塊參數(shù)對話框，在彈出的對話框中的查看模塊的默認參數(shù)，也能夠改變模塊的參數(shù)設置。表43 模糊控制規(guī)則表UENBNMNSZPSPMPBECNBPBPBPMPMPSZZNMPBPMPSPSZZZNSPBPSZZZNSNMZPMPSZZNSNSNMPSPMZZZNSNMNBPMZZNSNSNMNBNBPBZNSNMNMNBNBNB23第5章 系統(tǒng)仿真與調(diào)試 系統(tǒng)仿真模型的建立計算機的仿真過程是依據(jù)所研究的控制系統(tǒng)的實驗要達到的目標而建立起來的系統(tǒng)仿真模型，并在不同條件下通過計算機對建立的系統(tǒng)模型進行動態(tài)運行的過程。e，ec，u分別對應的模糊量為E，EC和U。為了保證系統(tǒng)能完全被控制一定要要求控制規(guī)則具有完備性。模糊控制跟其它的控制方法相比較，主要有一下幾個特點：(1) 模糊控制可以不用建立精確的數(shù)學模型，只要能夠掌握相關領域專家的以往知識和經(jīng)驗或操作或者是通過實踐得到的數(shù)據(jù)，因此比較適合數(shù)學模型難以精確的被控過程，以及系統(tǒng)結構和參數(shù)不是很清晰等場合。模糊解耦不需要系統(tǒng)有很精確的數(shù)學模型，進行起來比較簡單?？傊?，溫室的溫度和濕度這兩個環(huán)境因子有很強的耦合作用，兩者中的一個的變化會影響另一個的變化即存在相互影響，它們連同溫室里的其它環(huán)境因子共同構成了一個復雜的對象，要想對其進行很好很理想的控制是很難的，這需要系統(tǒng)各個部分的協(xié)力配合。并且，濕度的不適宜會導致作物產(chǎn)量的下降，由于溫室內(nèi)作物的不斷蒸騰作用和土壤的蒸發(fā)，溫室內(nèi)的濕度會很容易的比地面的濕度的高一些。第3章 解耦方法的選擇 系統(tǒng)環(huán)境因子的研究 溫度對作物的影響 溫度是影響農(nóng)作物生長發(fā)育相當重要的環(huán)境因素之一。 國內(nèi)外研究現(xiàn)狀和發(fā)展趨勢在溫室中對作物影響最嚴重的環(huán)境因子主要就是溫度和濕度這兩個因子，所以，對溫濕度進行智能解耦是當今溫室環(huán)境控制系統(tǒng)研究的主要方向，隨著我國溫室產(chǎn)業(yè)的不斷進步，溫室的大小和種類也隨之增加，我國的資源環(huán)境也跟著一步步短缺，所以，溫室也趨向于向節(jié)約資源同時高產(chǎn)高效的方向發(fā)展，如果溫度和濕度得到了優(yōu)良的解耦那么溫室的資源消耗就會大大的降低，溫室的這種特點尤其是冬季升溫和夏季降溫這兩個時候變現(xiàn)的更為明顯。但由于溫室內(nèi)較高的溫度和濕度這種不好的工作環(huán)境以及追求高效率、精準的作業(yè)，僅僅依靠人工來對這些環(huán)境進行監(jiān)控是不太現(xiàn)實的。此次研究的課題運用到了許多學科的新理論、新技術，本系統(tǒng)用的是智能控制中的模糊控制技術，針對很長時間以來溫室中的溫度和濕度存在很強的耦合關系和溫室溫濕度變化情況對監(jiān)控系統(tǒng)的反饋等問題提出了不錯的解決方案，提供了一種新的方法來解決系統(tǒng)控制不夠精準、能源消耗比較高、經(jīng)濟效益不理想等問題，同時也可以解決好時變性、大滯后和耦合性這些繁瑣的系統(tǒng)控制問題