Research On Anti-force Changeable Distance Roller Brake Testing Platform

With the rapid development of China's national economy and the improvement of people's living standards, the amount of vehicle increases incessantly. The traffic situation is becoming increasingly complex. Traffic safety has become a major social issue. Braking of the car is the most basic performance to protect the safe operation of motor vehicles and achieve the desired operational effectiveness. Car with good braking performance can be seizing the opportunity to avoid traffic accidents, in contrast, with poor braking performance, it is likely to cause a fatal car crash. For its special significance to the safety driving, braking performance is the most important aspect of vehicle performance testing, traffic management departments take it as a mandatory periodic one all over the world. At present, more than 80 percent of China's automobile performance detection stations use of anti-force-roller testing platform when testing braking performance. It has excellent performance, stable result of test, better test repeatability, convenience detection method and can work well with small space.But many problems were remain found in the inspection of this testing platform. For example, the testing car will be frequently qualified in the vehicle testing station A, but failed in B. In addition, there are also subjects of the vehicle braking normal, and the test results of stations has failed. Result of these phenomenon was mainly due to the detection equipment testing parameters caused by the inconsistency. As a matter of fact, whether can an accurate test data be drawn depends on the people, vehicles and equipment, three subjective or objective factors. Regardless of some subjective factors, people and vehicle, equipment functions as key causes. Since the productions which equipment maker produce have different roller diameter, test-center distance and rear roller higher than front one, result in different placement angle between wheel and roller, thus detection platform have different testing ability towards different car. Similarly, different models in the same brake test platform testing, as different diameter wheel; tire placement will be different angle, so different detection ability also. However, our country's standard of braking force detection is a unified, and this will directly affect the horizontal comparison of test data and test results'judge is impartiality.The purpose of this paper is to develop an anti-force variable-distance roller braking testing platform, finding reasonable placement angle to meet various types of automobile testing with similar detection ability. The study of this paper mainly includes the following:1. To introduce the structure of the current widespread use of anti-force roller testing platform and its working principle. Through analyzing the process of wheel braking on platform, identifying the trend of platform's testing ability by the influence of placement angle changing in a stable state and non-steady-state. In accordance with the detection of actual data which got from automotive performance testing station, analyzing detection ability in both states, drawn the conclusion that the detection ability in steady state is stronger than in non-steady state.2. Based on the dynamics analyzing of wheel on the platform, established dynamics model of braking procession in the environment of matlab/simulink. Contrasting the result of simulation with real experiment, the error is less than 5%, we could confirmed simulation model is closer to the actual truth of the working conditions. Utilizing simulation model test Jetta, Pajero, liberation automobile under placement angle from 25 to 35, showing that platform has similar testing ability for three types automobile when placement angle near 32 to 34. its test result can cover the largest adhesion force car on the road.3. Based on the result of Theoretical and experimental analysis, reconstruct the anti-force brake testing platform, designed changeable roller machine and transmission cable machine. Hydraulic servo control system has been designed and adopted the "master-slave" type of tracking and PID control method and to determine the parameters of the main components.4. After reconstruction, the equipment in accordance with the original control system has been added. Stated control theory of the changeable distance roller machine, selected AD card and sensor. Developed control system interface and designed the control system chart.For a long time in future, brake testing of automobile will mainly use anti-force roller braking testing platform. The development of new testing platform in this paper solves the problem of different car with different placement angle. Material condition is provided for the test results of horizontal fair comparison and evaluation, having a certain economic and social benefits.