Study Of Motor Vehicle Braking Performance Test System Based On Virtual Instument

The automobile braking performance affects the active security directly. To develop a quickly, accurate, and highly effective braking performance test system has the significance for enhancing the design manufacture level of the automobile braking system and for strengthening the ability of regular security detecting. The introduction of virtual instrument technology can reduce the system hardware expense, shorten the development cycle and enhance the system expansion ability. In this paper, applying the virtual instrument and the object-oriented analysis design method, taking the four wheels test bed as hardware platform, and taking LabVIEW as software development platform, the function strong and performance reliable automobile braking performance test system is constructed.The test system is composed by the hardware and the software two parts. In the hardware, the sensor, the personal computer and the data acquisition card are taken as the core device, and the signal adjust box circuit is matched The signal adjust box circuit having been designed includes some modules such as the system self-check, the analog signal filter and enlarge, the pulse signal restriction and reshaping, and the digital I/O signal isolation and reshaping and so on. The software part is composed by the top management program and the hardware driving program. The top management program mainly completes the gathering, memory, demonstration and analysis function for the scene examination signal and the control signal, as well as the inquiry and printing function for the historical signal. The hardware driving program is as dynamic link library (DLL) form for the top management program to recall, and mainly completes the functions such as working pattern setting, data gathering and transmission, and operation for the non-NI driving hardware and so on.With the base of the system software and hardware platform having been funding, using dynamics principle, the processing method of the test data such as the wheel rotate speed, the braking torque, the wheel cylinder pressure, the slip ratio and so on is researched. The realization of these data processing methods under LabWIEW7.1 development environment is analyzed with emphasis. Furthermore, the data acquisition module's design, the plan design of the test software and hardware subsystem and its control algorithm's realization.Finally, through the scene debugging work of the function modules, the system data acquisition and analysis's reliability is verified, and the debugging and the data analysis results are obtained. The results indicate that, the automobile braking performance test system can show the braking performance parameters such as the braking distance, the stop time, the biggest and smallest brake torque, the biggest and smallest braking pressure and so on real time, and can draw the corresponding test and analysis curve. It can realize real time test, data processing and analysis, test results output and other functions automatically, quickly and accurately. Furthermore, it can adapt the automobile of different ax, different wheel distance and different weightThe system has the characters such as its function is strong, its operation is convenient, its expanding is easy, its software and hardware design is safety and reliable, its usability is strong and so on. With this automobile performance test system, the examination precision and the examination speed of the automobile braking can be enhanced greatly, and it can be promoted to further application.