Modeling Of Brake And Research On Identification Of Parameters

The mathematical model of brake reflects the relationship between the brake torque and the brake pressure, depends on the different methods of modeling, the mathematical model of brake can divide into academic models and experiential models. The academic model is described by the mechanical theory and the geometry parameter of brake, and the experiential model is build by mathematical methods from the test data. By the different object of modeling, experiential models are divided into semi-static models and dynamic models. The friction coefficient change tardily in the braking process course the non-linear relationship between the brake torque and press is called semi-static model of brake.By the increase of speed of auto and highway largely, the energy consume during the braking process is more bigger, decay during the braking process is can't be avoided. In this situation, the linear model can't reflect the actual braking process. We should research the non-linear characteristic of brake, this paper build a semi-static experiential model based on abundant test, educe the variational characteristic of brake friction, and contrast the result of model and the result of test, prove the accuracy and the validity of the model. Specifically, the following research steps have been completed:1. Introduced the theory of brake system and kinds of brake simply, and analyse the dynamic of braking process of disc brake amply, divide the process into three moments: eliminate the brake gap, dynamic friction moment, static friction moment. Work out the differential eguation of each moment, and mainly introduce the method of calculate the brake torque of dynamic friction moment.2. By the result of investigate early times and the status quo of research of brake, choose the exponential function as the model of brake coefficient, and analyse the character of the model, and build a single DOF model of wheel.3. Research the test method of semi-static and dynamic character. Introduce the JF-122 test-bed simply, introduced the purpose, the character, the construction, the principle, the progress design and the operation method of the test bed. Study the method of design test, the method of deal with the test data. Using orthogonal regression experiment methods, do tests for semi-static model and dynamic model, research the influence of brake pressure and muzzle velocity to brake friction coefficient, and using the knowledge of statistic to validate the precision of the model.4. Using the Matlab/Simulink tool to simulate the brake coefficient model and single DOF model of wheel, in the same input of brake pressure, compare the output of brake torque and the rotate speed curve, and connect the brake coefficient model to the whole dynamic car model, and educe the torque curve and the rotate speed curve, and compare with the linear model.Above all, the research of this thesis is to build a dynamic model of brake with high precision, the model can follow the result of test data well, can used in the simulator to attend in the simulation of whole car in other situation, and can be a basic for farther research of performance of brake influenced by ABS.