外文翻譯----多傳感器的自我測(cè)量診斷系統(tǒng)-文庫(kù)吧資料
2024-09-04 17:13本頁(yè)面
【正文】 tial voltage range is and the step increment is then 100 diagnostic reference voltages (“read cycles”) need to be applied. To reduce the processing time of the diagnostic algorithm, successive approximation is used. The initial diagnostic reference voltage applied is in the mid value of the initial voltage range, . diagnostic scan is carried out. If the results from the “read cycle” show that there are more “ones” than “zeroes”, then the nonfaulty sensors lie above V and the next voltage range is from V to V (max). If the reverse is true, . more “zeroes” than “ones”, then the nonfaulty sensors lie below V and the next voltage range is from V(min) to V. second successive approximation is used to further reduce the range of the diagnostic reference voltage. After 2 stages of successive approximation, the initial voltage range has been subdivided into 4 regions (quartiles) and the software algorithm 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 located 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 are clustered close to the diagnostic reference voltages (V , V+) and the number of “ones” and “zeroes” cannot be 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 that the initial voltage range is and the incremental step size is and assuming that the surrounding temperature correspond to a voltage reading of . In the less successive approximation, the diagnostic voltage range is reduced to [, ]. After the 2 successive approximation, the diagnostic voltage range is [0V, . The limits of the voltage range are extended because of boundary conditions to [, and progressive scanning is carried out. Thus the diagnosis will take 2 + (78 47) = 33 cycles to plete instead of the original 100 cycles. Thus by using successive approximation, the voltage range to be scanned can be reduced drastically. IV. EXPERIMENTAL, RESULTS A prototype of the temperature measuring system was constructed using a MCB251 16bit 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 film 45℃ to 60℃ . The results are 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 ”C. This shows that the multi sensor system is able to provide an improvement to the accuracy of the temperature estimate pared to the single sensor system. Next faulty sensors are deliberately introduced into the system. Two types of faulty sensors are introduced: “faulty OW (outputs OV) and “faultyhigh” sensors (outputs VCC).The middle column of Table TI shows the effect on the measured temperature when 2,4 or 6 faultyhaymow sensors are introduced into the system at 25176。附錄AA MultiSensor Based TemDerature Measuring System with SelfDiagnosis Abstract A new multisensor based temperature measuring system with selfdiagnosis is developed to replace a conventional system that uses on
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