| In recent years,with the rise of RV tourism,and with the efforts of the Ministry of Industry and Information Technology and other departments and a number of production enterprises,the RV industry has shown a high-speed growth trend,and at the same time,the safety of RV has also attracted people’s attention.Due to the complexity of its own structure,the independence of the braking system and the coupling of the connecting device between the tractor and the trailer,the braking force of the tractor and the trailer may not match when braking,which may easily lead to traffic accidents.In order to solve the synchronization of trailer’s linear braking and improve the stability of vehicle’s linear-braking,this paper designs a synchronous braking control device for trailer under all working conditions,which can effectively reduce the negative longitudinal hook force between tractor and trailer,and is of great significance to the braking safety of trailer.In this paper,the linear braking of trailer is analyzed in kinematics,and considering the braking delay characteristics of the electromagnetic brake of trailer,the braking conntol strategy that the braking acceleration of trailer follows that of tractor is adopted to eliminate the braking delay of electromagnetic brake from the braking principle and improve the braking stability of trailer.The main research contents of this paper are as follows:Firstly,according to the characteristics of trailer,the kinetic model of linear braking and the mathematical model of braking torque and current of electromagnetic brake are established,and the relationship among braking acceleration of tractor,ground braking force of trailer,longitudinal hook force of trailer and driving conditions is analyzed,which provides a theoretical basis for putting forward braking stability strategy of trailer.Secondly,due to the uncertainty of the driving condition of trailer,it is necessary to detect the attitude information of the vehicle in real time.In this paper,the angular velocity,acceleration and geomagnetic information of the vehicle are measured by MARG inertial sensor,and the attitude calculation method such as quaternion method is used to detect the attitude of the vehicle in real time.Thirdly,this paper designs a synchronous braking control strategy for trailer trailer under all working conditions.Based on the linear braking dynamics model of trailer and the mathematical model of braking torque and current of electromagnetic brake,this strategy takes the braking acceleration of tractor as the target tracking signal,and uses cubic spline interpolation function to expand its data,and uses grey model to predict the braking acceleration of tractor at the next moment as the following braking acceleration of trailer.According to the relationship between the braking torque of the RV and its following braking acceleration under the current driving condition,the braking torque should be calculated and converted into a current signal to control the electromagnetic brake to brake the RV,which can eliminate the braking hysteresis effect of the electromagnetic brake from the braking principle and realize the synchronous braking of the trailer.Finally,based on Carsim and Matlab/Simulink platform,the joint simulation of trailer’s linear braking is carried out to verify the effectiveness of the control strategy of trailer’s synchronous linear braking,and the hardware circuit of the control system is built according to the main functions of trailer’s synchronous braking system to complete the development of trailer’s synchronous braking. |
