| Automobile brake performance test, as one of the most important projects of motor vehicle safety inspection, has been the focus of attention. At present, Roller Opposite forces Type Automobile Brake Tester is widely used in domestic, which generally adopts computer control technology to acquire and process braking force data. My project provides a test method of opposite forces Type Automobile Brake Tester. Firstly, respectively corresponding to the left and right wheels of the motor vehicle, the reseacher uses a computer to generate two fitting brake curve. Secondly, using digital to analog conversion way generates electrical signals, and adjusting amplitude and impedance to match the sensor output signal of the tester. Thirdly, we need to send the two signals to test system, and compare test results and the known brake curve, check the error of test system to realize the test of opposite forces Type Automobile Brake Tester.Based on the overall design of the system, the design of the hardware and software is given, which makes the system achieve the design target to output low frequency signal, and this design scheme provides simple PC software. The system hardware consists of three parts, one part is the LPC11U14 micro control unit based on ARM Cortex- M0 kernel, the second part is the USB communication unit, and the third part is DAC signal output control unit. Accordingly, the system software is divided into three parts, the first part is the LPC11U14 on-chip peripherals drivers, the second part is the realization of USB protocol stack, and the third part is the DAC driver software. PC software is developed using C programming language in the integrated development environment Labwindows/CVI provided by NI, and this design implements the USB device driver by means of the NI-VISA technology.This design completed the system hardware, software design, PCB design and system integration and test, the test results show that the system runs stably and reliably. |
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