Design And Implementation Of Sensor Converter Test Bench

The sensor converter test bench is a unit test equipment designed for the testing requirements of related sensor converters in aircraft performance testing.It is mainly used for signal acquisition,signal provision,and communication interface function testing of certain types of sensor converters.The purpose is to help testers better analyze the performance indicators of the tested target sensor converters through automated testing methods.According to specific functional requirements,the test bench is designed with the following functional modules: power supply output module,thermocouple signal acquisition module,voltage signal acquisition module,programmable voltage output module,and digital communication module.The communication loop of each module is constructed using PCI(Peripheral Component Interconnect)bus,and programmable software logic design is performed based on FPGA(Field Programmable Gate Array)to achieve embedded software logic functions of each module.The power supply output is based on the AC-DC(Alternating Current to Direct Current)module to provide a stable DC source,utilize programmable switches to gate the output,and take overcurrent protection measures to provide a stable supply for the4-way power output,which can cover the power supply requirements of most commonly used test equipment.The thermocouple acquisition module performs signal preprocessing through cold junction compensation,utilizes filters and overvoltage protectors to ensure signal fidelity and reliability,and accurately acquires the measured signal through high-precision acquisition.The voltage acquisition module relies on a linear regulator to provide a reliable working power supply for the circuit,and uses a step-down device combined with the acquisition circuit to achieve high-precision acquisition with variable range.The program controlled voltage output module realizes the program controlled output of voltage based on DAC(Digital to Analog Converter),relies on dynamic adjustment circuitry to ensure anti-interference of the output,and sets output protection to ensure the safety of the output signal,achieving reliable output.The digital communication module utilizes high-speed synchronous transmission and asynchronous multimode transmission to achieve multimodal communication with the device under test to comprehensively detect its functional correctness.Use experimental equipment such as an oscilloscope and multimeter,and follow standard experimental procedures to verify the completeness and reliability of equipment functions.Through experiments,the output of four power supply channels is stable,and the minimum error of 28 V,+12V,-12 V,and 5V voltages can reach 50 m V.At least 0.5A of driving capacity can be maintained at-12 V output.At 28 V and 5V output,over 1A of driving capacity can be achieved,and at 12 V output,over 2A of driving capacity can be achieved.The thermocouple signal acquisition module can achieve 8-channel(-70～70)m V voltage acquisition,and the absolute value of measurement error is ≤ 0.05 m V.The voltage acquisition module can achieve12 channels(-10～10)V voltage acquisition,The measurement error accuracy can be controlled within 0.1% FS.The programmable voltage output module can stably achieve a DC voltage output of(-80～80)m V and maintain an absolute error value of ≤ 0.04 m V.The digital communication module can achieve synchronous communication with a period of 5 ms and a rate of 10 Mbps,as well as asynchronous UART communication with a baud rate range of(115.2～921.6)Kbps,while maintaining no frame loss and no data loss,ensuring the stability of the communication process.The overall function of the test bench is normal,meeting the application requirements in sensor converter testing and measurement.