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1、<p><b> 附錄A</b></p><p> A Multi-Sensor Based TemDerature Measuring System with Self-Diagnosis </p><p> Abstract- A new multi-sensor based temperature measuring system with
2、self-diagnosis is developed to replace a conventional system that uses only a single sensor. Controlled by a 16-bit microprocessor, each sensor output from the sensor array is compared with a randomly sel
3、ected quantised reference voltage at a voltage comparator and the result is a binary “one” or “zero”. The number of “ones” and “zeroes” is counted and the temperature can be estimated using statist</p>
4、<p> Transducers </p><p> I. INTRODUCTION </p><p> Conventional sensing system uses a single sensor to convert a measured into an electric signal. There is no built-in r
5、edundancy and the system is wholly dependent on the single sensor for its accuracy. Recently, a novel approach proposed by the author in [l] makes use of the principles of successive approximation and statistical es
6、timation to provide </p><p> a simple yet accurate estimate of the measured with only a small number of sensors. Replacing the single sensor with a multi-sensor array also improves the robustness of the
7、 system reducing system dependency on any single sensor. The system is still functional even with a few faulty sensors, though there will be a degradation in the accuracy of the </p><p&
8、gt; results. To overcome the degradation in the accuracy due to the presence of faulty sensors, a self-diagnostic algorithm is devised to determine and isolate faulty sensors so that these sensors are not used
9、in the determination of the temperature estimate. In this paper, the development of such concept into </p><p> a practical system for temperature measurement is described. </p><p> II. SYS
10、TEM ARCHITECTURE AND OPERATION </p><p> A. System Hardware Architecture </p><p> The hardware system consists of 36 temperature sensors in a ensure array, a signal conditioning circuit an
11、d a 16-bit micro- controller, as shown in Fig. 1. Each sensor, controlled by an analog switch, measures temperature and outputs a voltage. The output from all 36 sensors are fed into a switching </p>&
12、lt;p> circuit. The switching circuit consists of a decoder and an analog multiplexer that is controlled by the software to sequentially select an output from all the 36 sensors. The selected output
13、 is fed into the signal conditioning circuit for processing before being sent to the microcontroller. One complete “read cycle” involves reading the outputs from all 36 sensors. The sensors used in the sen
14、sor array are calibrated beforehand to obtain their voltage-temper</p><p> B. Temperature measurement </p><p> To obtain an estimate of the output temperature, mathematical princi
15、ples of successive approximation and statistical estimation are used. The analog sensor output are sequentially selected by the switching circuit and passed onto the non-inverting input of a voltage comparato
16、r for </p><p> digitization. A reference voltage that is determined by the software program is applied to the inverting input of the voltage comparator. If the analog sensor voltage is highe
17、r than the reference voltage then the output at the comparator is a binary “one”, else the result is a binary “zero”. </p><p> The initial reference voltage range of is established based on apriori
18、ty </p><p> knowledge of the characteristics of the temperature sensors and the temperature range to be measured. The voltage range is then quantized into m different levels with an equal step su
19、e of where m is the number of sensors in the sensor array and represents the maximum and minimum value of the initial voltage range before any successive approximation is carried out. The m reference vol
20、tages are randomly sorted. For each reading from the sensor array, a quantized refe</p><p> microcontroller for so hare processing. The microcontroller counts the number of binary “ones” in a read cy
21、cle. Based on the number of “ones”, statistical estimation is used to obtain the temperature estimate V as follows. If the accuracy of the estimate, given by Arid, does not meet a predetermined level, succ
22、essive approximation is carried out to reduce or narrow down the reference voltage range. The new reference voltage range for the new “read cycle” is given . w</p><p> III. SELF-DIAGNOSIS </p&
23、gt;<p> The self-diagnosis algorithm is a software controlled procedure to detect whether any of the sensors in the array is faulty, to isolate and deactivate any faulty sensors present and to compensate
24、for the faulty sensors. The diagnosis assumes that the majority of the sensors in the array are in good order. A sensor is classified as faulty if its measurement is more than x℃ from the actual temperature
25、.where x is a user defined value depending on the temperature sensor use</p><p> comparator for all the sensor outputs in a “read cycle’’. In principle, all the sensors are expected to produce
26、the same digital out& with two exceptions: when the reference voltage is very close to the voltage corresponding to the actual temperature ; if the sensor is faulty and gives rise to an inaccurate output dif
27、ferent film those of the majority sensors. Thus as the reference voltage applied to the comparator is shifted between him V (min) to V (max), it sho</p><p> state. Incrementing the status co
28、unter of a sensor indicates a high probability that the sensor is faulty. In Fig. 3 both sensor 20 and 26 will have their software counters incremented for the V, level since they belong to the minority state. The
29、constant reference voltage is shifted between the extreme ends of the voltage range through scanning (moving from V(min) to V (max) in fixed increments). For each diagnostic reference voltage applied, all s
30、ensor inputs are scanned</p><p> more “zeroes” than “ones”, then the non-faulty sensors lie below V and the next voltage range is from V(min) to V. second successive approximation is used to fur
31、ther reduce the range of the diagnostic reference voltage. After 2 stages of successive approximation, the initial voltage </p><p> range has been subdivided into 4 regions (quartiles) and the software a
32、lgorithm is able to determine which quartile does the majority of the sensors fall into. The upper and lower limit of the diagnostic voltage range of the quartile where the majority of the sensor readings are lo
33、cated is extended by 3 times the diagnostic incremental size to take care of boundary conditions. Boundary conditions occur during the successive approximation stages, when the sensor voltage readings a</p>
34、<p> accurately determined. Within this reduced diagnostic voltage range, the diagnostic reference voltage is sequentially incremented to detect the faulty sensors. Using the earlier example, it is given
35、that the initial voltage </p><p> range is 1.0V and the incremental step size is 0.01V and assuming that the surrounding temperature correspond to a voltage reading of 0.6V. In the less success
36、ive approximation, the diagnostic voltage range is reduced to [0.5V, 1.0V]. After the 2 successive approximation, the diagnostic voltage range is [0V, 0.75Vl. The limits of the voltage range are extended becau
37、se of boundary conditions to [0.47V, 0.78VI and progressive scanning is carried out. Thus the diagnosis wi</p><p> IV. EXPERIMENTAL, RESULTS </p><p> A prototype of the temperature me
38、asuring system was constructed using a MCB251 16-bit microprocessor and 36 LM35DZ temperature sensors that have an individual accuracy off 1℃ The system was then tested in an oven over a temperature range fi
39、lm 45℃ to 60℃ . The results are </p><p> shown in Table I. It can be seen that very accurate results over the temperature range of 45℃ to 60℃ are obtained. The maximum error is 0.05”C. This
40、 shows that the multi- sensor system is able to provide an improvement to the accuracy of the temperature estimate compared to the single sensor system. Next faulty sensors are deliberately introduced in
41、to the system. Two types of faulty sensors are introduced: “faulty- OW" (outputs OV) and “faulty-high” sens</p><p> measured temperature when 2,4 or 6 faulty-haymow sensors are introduced int
42、o the system at 25°C. The accuracy of the temperature measurement decreases as the number of faulty temperature sensors increases. The system exhibits a degree of robustness at the presence of faulty sensors at t
43、he expense of degradation in the accuracy of the temperature measurement. </p><p> CONCLUSION </p><p> A multi-sensor based temperature-measuring system with self diagnosis is described
44、. Based on successive approximation and statistical estimation, the system is able to produce accurate temperature measurement using a small number of sensors. With a multi-sensor array, the system ex
45、hibits a certain degree of redundancy although the accuracy is degraded when faulty sensors exist. A diagnostic algorithm is developed to identify% the faulty sensors and subsequently</p><p>&
46、lt;b> 附錄B</b></p><p> 多傳感器的自我測量診斷系統(tǒng)</p><p><b> 摘要</b></p><p> 一個新的傳感器的溫度測量系統(tǒng)的自我診斷、開發(fā),以取代傳統(tǒng)的系統(tǒng)只使用一個單一的傳感器。由16位微處理器,每個傳感器輸出的傳感器陣列是與隨機選取的參考電壓進行電壓比較,結果是一個二進制的“
47、1 ”或“0” ?!?”和“1”的計算使用統(tǒng)計估計和逐次逼近方法。軟件診斷算法是發(fā)達國家來檢測和隔離故障的應用于傳感器的算法,可以用在傳感器陣列,并可重新調整系統(tǒng)。 實驗結果表明,溫度測量獲得準確數(shù)據(jù),與自我診斷算法的準確性,及系統(tǒng)是否存在故障傳感器密切相關。</p><p><b> 導言</b></p><p> 傳統(tǒng)的傳感系統(tǒng)使用一個傳感器轉換測量成電信號。
48、不存在內(nèi)置冗余和系統(tǒng)的完全依賴單傳感器的精度。最近,一種利用一種原則提出新的方法, 逐次逼近和統(tǒng)計估計提供簡單而準確的估計的測量,只用少量的傳感器,取代了傳統(tǒng)只用單一的傳感器的方法, 多傳感器陣列還提高了系統(tǒng)的準確性,降低了系統(tǒng)依賴于任何單一傳感器,甚至那個系統(tǒng)有一個故障的傳感器。為了克服由于存在故障的傳感器系統(tǒng)準確性的問題,自我診斷算法是設計一種方法,以確定和隔離故障的傳感器,使這些傳感器不被用來測定溫度數(shù)值。本文的發(fā)展,這種概念納入
49、實際系統(tǒng)的溫度測量中。</p><p><b> 系統(tǒng)架構和運行</b></p><p> 他的硬件系統(tǒng)由36個溫度傳感器在恩索爾陣列的信號調理電路和一個16位微控制器所組成 。每個傳感器,有專門的控制的開關和輸出電壓。 所有的輸出36傳感器輸入開關電路。開關電路由一個解碼器和一個模擬多路控制軟件按順序選擇一個輸出。那個選定的輸出輸入信號調理電路處理前被發(fā)送到微控
50、制器。一個完成校準的傳感器用于傳感器陣列的校準,事先獲得其電壓溫度特性。其一系列數(shù)據(jù)被認為是線性的溫度數(shù)據(jù),才能在一個方程中使用,用軟件算法轉換電壓讀成溫度讀數(shù)。</p><p><b> 溫度測量</b></p><p> 要獲得的估計輸出溫度, 數(shù)學原則,逐次逼近和 統(tǒng)計估計方法。模擬傳感器輸出的 關于選定的順序開關電路和轉嫁 非反相輸入電壓比較。參考電壓是確
51、定的 ,軟件程序是用于反相輸入的 電壓比較。如果模擬傳感器電壓高比參考電壓那么輸出的比較結果是二進制“ 1 ” ,否則其結果是一個二進制“0” 。 基于Apriority 的特點,用溫度傳感器和溫度范圍來衡量電壓范圍 。然后根據(jù)quantized不同層次的步驟 ,說明的其中那些是一些傳感器 、傳感器陣列和代表 最高和最低值的初始電壓范圍 ,這些都要在逐次逼近之前進行。對于每個 傳感器陣列,一個參考電壓 是隨機挑選的比較在電壓進行 比較。
52、這是為了減少依賴任何傳感器參考電壓。輸出的比較值,是二進制“ 1 ”或“0”。那個 參考電壓生成軟件 算法和轉換成模擬電壓通過一個12 - 位數(shù)字到模擬轉換器 。一個完整的周期及處理模擬傳感器電壓所有36傳感器,從而獲得36位二進制數(shù)據(jù)。 二進制輸出比較是交給 微控制器的shore處理。微控制器清點二進制的“1”讀周期。基于 數(shù)量的“1” ,統(tǒng)計估計是用來獲取溫度估計值的。 如果精卻的估計,所給予參考電壓 ,不 滿足</p>
53、<p><b> 自診斷</b></p><p> 自我診斷算法是一種程序來檢測是否有任何傳感器陣列故障的,孤立和停用任何故障傳感器本和為了彌補故障的傳感器。診斷假設大多數(shù)傳感器陣列中的良好秩序。如果一個溫度傳感器的測量值X不同于的實際溫度 ,則它被列為故障的傳感器。其中x是一個用戶定義的值,取決于溫度傳感器的使用和精度要求。診斷同時參考電壓應用于電壓比較所有的傳感器的“閱
54、讀周期'' 。在原則上,所有的傳感器將產(chǎn)生同樣的數(shù)字。但有兩個例外:選擇的參考電壓,是非常接近相應的電壓的實際溫度;如果傳感器出現(xiàn)故障,并帶來一個不準確的輸出不同與那些大多數(shù)傳感器。因此,作為參考電壓適用于比較之間變換速度。它應該能夠分開好的與故障傳的感器。診斷算法如下。在某溫度下,不斷選取參考電壓應用于比較所有的傳感器陣列??倲?shù)的“1”和“0”的計算。一個傳感器屬于少數(shù)可能是錯誤的。每個傳感器具有相同的軟件的地位,與它
55、相關的是最初設定為零開始時診斷常規(guī)。這個計數(shù)器遞增,如果傳感器被認為屬于少數(shù)的狀態(tài)。表明其實高概率的故障傳感器。通過掃描 最大最小值,來不斷改變參考電壓之間極端的電壓范圍內(nèi)。對于每個診斷參考電壓適用,則所有傳感器進行掃描 。在整個電壓范圍已經(jīng)掃描過后,</p><p><b> 實驗結果</b></p><p> 原型的溫度測量系統(tǒng)建議使用MCB251 16位微處
56、理器和36 LM35DZ溫度傳感器,其具有良好的精確度。系統(tǒng)測試,在烤箱溫度范圍45 °C至60°C結果中可以看出,在溫度范圍45° C至6O° C的數(shù)據(jù)中,最大誤差僅為0.05°C。這表明,多傳感器系統(tǒng)較單一傳感器系統(tǒng)能夠提供的更精確的溫度測量。故障傳感器引入系統(tǒng)。兩種類型的故障傳感器介紹: 輸出過壓傳感器和產(chǎn)出虛擬數(shù)據(jù)傳感器 。</p><p> 結論多傳
57、感器的溫度測量系統(tǒng)的自我診斷方法。基于逐次逼近和統(tǒng)計估計,該系統(tǒng)能夠產(chǎn)生精確的溫度測量使用少量的傳感器。與多傳感器陣列相比,系統(tǒng)減少了一定程度的冗余。雖然精度不高,但當傳感器存在故障。診斷算法能找出故障傳感器,隨后停用他們。與診斷算法相比,該系統(tǒng)能夠分離出故障傳感器和生產(chǎn)準確溫度測量。不同于傳統(tǒng)的遙感系統(tǒng),該的系統(tǒng)采用了少量的傳感器的測量來確定參考數(shù)據(jù),并逐次逼近和統(tǒng)計估計。系統(tǒng)沒有內(nèi)置冗余,并可以改善測量。這個系統(tǒng)有廣泛的通用性,并可
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