Research Of The Automatic Test System For Vehicles Exhaust Based On Two-Speed Idle

As the quantity of the automobile increasing rapidly,the test and diagnosis of automobile is becoming more and more important.The method under two-speed idle condition is one of the effective methods.As a result of realizing the automatic test system,it can cut labor intensity,improve the precision of test vehicles exhaust and improve the level of test and diagnosis.The control system bases on double single-chip.Based on the communication between K-line,OBDII and the ECU,the communication module which can acquire the rotate speed is designed.Based on the rotate speed,the rotate speed of engine which is controlled is realized at the same in period of time.The data which is tested form exhaust is acquired automatically by the acquired module.The module of rotate speed controlled is composed of step motor and gearing.The data acquisition is realized by the communication with exhaust gas analyzer.The automatic test system for test vehicles exhaust is developed based on two-speed idle.Because the rotate speed is acquired by communication and it is indeterminacy when the data is transmitted,there is indeterminacy time delay in the control system.In order to improve the control quality,it probes into the control of time-delay system.When the delay time is short,it adopts the Smith predictor;when the delay time is too long,it chooses the extrapolation.Do some simulations by MATLAB,they prove that the control method is very effectively.It is proved the system working stability by the experiment.It can control the rotate speed within Chinese Standard range and keep the test time accurately. The research goal is achieved.