The Software Processing Research On Several Sensors And Actuators In Engine Control System

Sensors and actuators are important parts of the engine control system. Sensorsresponsible to the electronic control unit (ECU) to provide information on the engineoperating state, or as a closed loop feedback control elements reflects the amount ofcharged state. Actuators adjust instruction are based on the amount of ECU which ischarged to achieve the setted targets. Error recognition sensors signal and incorrectoutput actuators control signal will result in disastrous control results. Therefore, theaccuracy and rationality of being measured and controlled are essential for effectivecontrol of the engine. It is requires not only ensuring a good match between theelectronic control unit hardware interface circuit with sensors and actuators, but alsorequires optimizing signal processing of engine sensors and actuators on the softwarelevel.Modern engine management system (EMS) uses control strategy be based on ahierarchical model and the software architecturewidely, realizes the sensor input signalsoftware management by the application-layer sensor module, converts the samplingsensor voltage signal into the corresponding of physical quantity, and the process ofreasonable judgment and signal diagnostics. The actuator assembly to the applicationlayer switches the control signal generated by the controller to the actuator drive signaland conducts the corresponding of limiting process. In this paper, against at several oftypical sensors and actuators in engine control system, to research the amount andfrequency of analog input signals and the discrete and PWM of output signals bysoftware processing methods. The main contents in this paper include:（1）The processed strategy of analog sensors signal by software. For the position ofthrottle, the pressure of intake manifold, the temperature of intake air and the switch ofoxygen sensors, used a static characteristic function or the lookup table of input/outputcharacteristics to represent the physical properties, then, carried out the conversions.Using the method of time delay and low-pass filters defibrillated the signal signals.According to the nominal threshold ranges checking and judging the reasonableness ofthe signals. Last but most, acquired the output signals by diagnosis and judgement.（2）The processed strategy of frequency sensors signal by software. For thecrankshaft position and the camshaft phase sensor, according to the signals which isacquired by hardware circuit, to check teeths and adjacent edentulous period, judged thereasonableness of the signal. Through checking the amont of teeths during eachcamshaft rotation cycle, the accuracy of the diagnosis was finished. Crankshaft and camshaft signals carried out through the establishment of the synchronization signalcharacteristics containing crankshaft and camshaft lookup table. The signal processingis realized by using filtering, integral and differential diagnosises. When the camshaftsignal deviation occurs, we would use the adaptive algorithm to adjust the camshaftsignal.（3）The processed strategy of frequency actuators signal by software. For thedispersed quantity of alarm lamp signal, the controled signal of ignition coils and themotor of driving throttle by PWM signal, which is used different of processing methods.According to the state of the engine, we determined the priority of alarm lamps workingpatterns, and calculated the output of state by the state machine. Determine the coilcurrent time and discharge time of spark plug which is based on the lookup table ofcalibration. According to check the threshold range of inspection, we determined thereasonableness of the ignition output signal. According to the throttle position, the dutycycle of the PWM signal was generated by the PWM signal generator, the time delaywas eliminated through the dither signal. According to the threshold limit value, wejudged the reasonableness of the signal.For these sensors and actuators above all, which is based on ETAS/ASCET platformto establish a corresponding signal processing models, and by the signal of processinglogic simulation correctness, the foundation of the EMS application layer software wasbuilt.