Research On Embedded Sotfware Testing Of EPS Through ECU In The Loop Simulations

As in recent years, Electric Power Steering system (EPS),which featured byenvironmental friendly, energy saving, having a excellent maneuver, have becoming moreand more popular among constomers and car manufacturers. In consequence, engineerswho develop EPS embedded software gradually realize that software test has greatersignificance in respect of drivers’ safety.Relying on university-enterprise cooperation project–‘An A0rank car’s EPS systemdevelopment’,this article will study the software testing throughout the developmentprocess,and finally resolve the problems using an application of ECU in the loop simulationtechnology.The establishment of ECU-in-the-loop test environment is the basis of ECU softwaretesting. This article carries out the work at two levels. Firstly, based on the Matlab/Simulink/xPC-Target, I established the ECU-in-the-loop simulation testing environmentfor a real-time simulation and the ECU input signal simulation. In this process, I made theanalog output cards and digital/frequency output card, which can generate real-timeanalog, digital and analog signal according to the instructions received from the CAN bus.Secondly, I established a model-based testing environment for EPS ECU software whosefocus is the unit under test model and control strategy model. Established EPS bench modeland vehicle testing model. Vehicle testing model is Established with veDYNA software, andI changed its Steering system model, so that it can carry out the steering wheel and powerinput simulation. Developed the EPS control strategy model for ECU software testingapplications. On this basis, took advantage of the EPS ECU prototypes and automatic code generation which our research group has developed, I established the EPS ECU under testprototype.Based on projects above,the article mainly research on three test technologies，simply，the control logic testing, fault logic testing and realization of test automation.The aim of control logic test is that examine the software after having known controllogic, and check the fault from the manual coding. software. The control strategy errorsimulating and evaluating the test results are the main technical difficulties. To simulate thecontrol strategy software error,We apply the method that stimulating the possible controlstrategies according to typical test conditions respectively. Because an error will be reflectedon the difference of two test graph which represent on the HIL and SIL experiments.In thisprocess, we need a right control strategy model as we done before. So this article measurethe error with ECU in the loop simulation. The target graph in this has been developed inprevious work.Fault logic test of ECU software testing is of great importance, it is to confirm whetherthe fault detection and response is consistent with the design purpose. Test case preparationand management, fault simulation and test results determination are the main technicalpoints. For the former, this paper use the fault test case definition table to manage andstandardize definitions, with the advantages of continuing the additional and revised tofacilitate follow-up test cases. According to the test case definition table, this paper builtSimulink fault simulation modules.The results is determined with a methedcalled”Analysing whether the ECU would produce the desired fault code andfault level code within the specified time”.When the failure tests accumulate to large quantities,it is necessary to realize the testautomation. The article adopt this solution to tackle the heavy and complex test job.Thismethod is featured by ’using trigger parameterto realize the random control for failurecombination and arrangement and using CAN bus to facilitate M files to achieveautomation. Finally, the article prove that this method has such merits as adding andadjusting test examples. Eventually,in actual process of embedded software test,we achieve an obvious testresult by using methods studied above efficiently.