| The brake testing on the test platform is one of the most important technological means for automotive braking security testing, and the braking performance is directly related to driving safety. This paper developed the method to calculate automatically the wheel diameter and regulate automatically the distance of rollers for a new anti-force rolling brake testing platform. The structure parameters of the test platform were described and the analysis of the forces applied on the test platform was presented. The relationship of braking force and height difference between the main roller and the secondary roller, formed angle was studied. A model calculating wheel diameter was proposed and the wheel diameter was calculated based on the position of the third roller. The distance between the main roller and the secondary roller was calculated based on setting formed angle and wheel diameter, and the distance was adjusted and the chain was tightened using hydraulic unit. The real vehicle testing results show that braking force testing can be improved by adjusting the distance between the main roller and the secondary roller.The main works around the techniques of regulate automatically the distance of rollers for a new anti-force rolling brake testing platform are described in the following sections.The mechanical structure of new roller reaction vehicle braking test platform was described and kinetic analysis of the test platform was conducted, and the rules of impact of the axle load, roller height difference, setting angle, roller surface adhesion coefficient, tire pressure, sampling frequency of braking signal and driver’s driving operation on the test precision of braking test platform were also tested and analyzed. The results of field vehicle test show that adjustment of roller distance and the change of tire pressure can have significant impact on the braking dynamic test result.In order to truly reflect the brake performance of automobile during full load, this paper researched platform type load test method of automobile brake performance, which had important significance to effectively conduct automobile full load brake performance test. Then this paper researched lifting load brake test method, analyzed the lifting load brake test principle and test method, the analysis result showed that two-axles automobile was not suitable to utilize lifting load method, as for multi-axles truck, adopted the method of lifting load on intermediate axle could effectively measure the braking force of automobile. Adjust wheelbase type load brake test method was researched, and then this paper analyzed the adjust wheelbase type lifting load brake test principle and test method, analysis thought that as for all the axles of two-axles automobile, multi-axles truck with three-axles, more than three-axles, adopting dual-axis trailer and three-axis trailer, all the vehicle braking force could be effective measured with the method of adjust wheelbase type load. This paper researched the tension and compression type load brake test method, then analyzed the load brake test principle and test method with tension and compression type, the analysis thought that it was suitable for various automobile types. Finally, this paper conducted comparative analysis on lifting load brake test method, adjust wheelbase type load brake test method, tension and compression type load brake test method.In order to accurately test the brake performance of automobile, this paper constructed friction loss model of brake testing platform, so as to conduct modification on the test result of braking force. Defined the relative slippage amount. After this, this paper constructed the friction loss model of anti-force brake testing platform depended on relative slippage quantity and placement angle. The result showed that, the friction loss model was effective, which could provide base to amend the friction loss of vehicle brake’s braking force. In order to improve the accuracy of test result of anti-force rolling brake testing platform, the friction loss caused by placement angle change shall be amended. After this, the automobile braking ratio shall be discriminated according to GB7258-2012 and GB 21861-2014. |
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