The Design Of Oxygen Sensor Test Equipment

With the continuous development of the scale of the automobile market,the automotive electronics industry has entered a stage of rapid development,but the pollution problems are getting more and more attention,oxygen sensor works through converting the oxygen difference into voltage,and then feed back to the electronic control unit to control the fuel injection amount,so that the mixed gas reaches an optimum combustion ratio.Since oxygen sensor were invented and applied to the car exhaust system,the technology has undergone rapid development,product types are more and more diversified,develop towards higher accuracy,higher performance direction,so for the newly developed product,performance test is particularly important.the oxygen sensor performance test items are more complex,in addition to conventional static and combustion tests,but also the need for open-loop and closed-loop characteristics' test,and can get specific data and graphs.This requires the test equipment not only be able to simulate the true working environment of the oxygen sensor,but also can according to the oxygen sensor product category to switch the different interface circuit.through upper and lower computer communication to analyze and preserve test data,if necessary,to facilitate and maintain the system program efficiently.Based on the Cortex-M3 platform to design an oxygen sensor performance test equipment,the mechanical control platform and heating table are separate to ensure that oxygen sensor can reach the operating temperature as soon as possible,without affecting the performance of the main control system.system control board is based on STM32 control circuit design,also including the power supply circuit design,the oxygen sensor heating circuit design,data acquisition circuit design,serial communication circuit design,multimeter switching circuit design and other hardware circuits.the software design including the upper and lower computer communication program design,The design of the air-fuel ratio analyzer communication program,PWM control program design,ADC program design and IAP,CRC program and so on.The host computer test is developed by Python language,including the design of the host computer interface,the design of the test process,the test configuration program design,the interface is simple and easy to operate,the test data are analyzed by MATLAB,to get the output graph and verified data.the system through the air-fuel ratio analyzer to obtain ? value,through the upper and lower computer communication,we can clearly read and save the test results,operating the test process at the same time.The device can be upgraded via USB field debug and serial IAP design.