Research On Bench Testing Technology Of Automobile ABS Dynamic Performance Based On Inertia Simulation

ABS is a kind of improved technology based on general braking device, ithas common brake function of mechanical braking system, and also preventswheel from locking, it controls the braking torque on the wheel automaticly,makes the adhesion coefficient between the tire and road surface in near peak,shortens the braking distance maximum, improves the braking performance andprevent vehicle from sideslipping by adjust brake pressure of wheel cylinder. SoABS obtains fast development and widely used in automotive field. However, inthe aspects of using different ABS control algorithm in different conditions totest vehicle braking performance, the test method is very single used at home andabroad. The adhesion coefficient between tire and road surface is hard to be fastand accurate changed and the braking distance is also hard to estimate. So it can’tsatisfy the performance testing needs of ABS in the development process.This dissertation puts forward a bench test method of automobile brakingperformance. It is suitable for different road combination that based on furtherresearching working principle and testing technology of ABS.This method is kindof independent test method based on the flywheel inertia simulation. Theprinciple of this method is to simulate the translational kinetic energy of realvehicle by the rotational kinetic energy of flywheels, to dynamic simulate thebrake road conditions by using magnetic clutch.The adhesion coefficient betweentire and road surface is realized by controlling torque transmission betweenmaster and slave shaft of magnetic clutch. PC sends adhesion coefficient data tomagnetic clutch and single-chip microcomputer controls driving circuit to trackthe target current. The exciting current is closed-loop controlled by self-tuningfuzzy PID control method. The whole system can realize not only single adhesive coefficient of the road surface and reciprocal adhesive coefficient of the roadsurface, but also docking adhesive coefficient of the road surface. Thus it canmake performance evaluation to road condition recognition ability and dynamicresponse.By Analyzing Automotive dynamics and factors lead to wheel lock，wesummarize vehicle antilock braking characteristics，establish vehicle dynamicmodel in the process of brake, mechanical braking system model, tire-roadfriction model, automobile braking distance model and related theoreticalderivation, sum up the ideal braking process and the relationship between tire-road friction characteristics and slip rate in the braking process. We also analyzethe influence of wheel rotation inertia to the wheel motion state and severalmature ABS control strategy.This dissertation also has detailed explanation on mechanical structure ofABS test stand and operating principle, analyzes the overall design scheme andimplementation technique of data acquisition system. Put forward the modulardesign methods based on CAN-BUS and in-depth study wheelspeed signalprocessing method and magnetic clutch exciting current control algorithm.Finally, the dissertation makes further feasibility validation by a group ofexperimental data. This test method has good solutions to the problems such asbrake pressure is not easy to measure, slip rate computation is not accurate, thefriction coefficient between tire road is difficult to adjust and greatly improvedprecision and data repeatability.The research content of this dissertation belongs to auto safety and test areas.By researching dynamic performance testing methods and data acquisition andcontrol system, it can realize independent tests of ABS braking performance,shorten test cycle effectively, reduce test cost. At present, automobile brakeperformance test technology is still in the stage of development. Thedevelopment of the technology can provide new technical scheme for thedomestic automobile testing industry and scientific research colleges anduniversities which can promote the development of China’s automobile testingtechnology.