Real-time Estimation Of Commercial Vehicle Mass And Road Slope

The real-time quality and road slope estimation of commercial vehicles can provide basic data support for vehicle running process monitoring and driver behavior evaluation system.In view of the characteristics of adding vehicle quality and road ramp detection device in commercial vehicles,it is difficult to realize and be widely used,using CAN(Controller Area Network)bus data to estimate these parameters is a more acceptable way for users and oems.Based on this,this paper studies the estimation algorithm of commercial vehicle total mass and road slope and realizes the algorithm in embedded device.The main research contents of this paper are as follows:(1)Considering the influence of engine flywheel and wheel inertia on vehicle dynamics under high transmission ratio of commercial vehicle,the longitudinal dynamics model of commercial vehicle is established.The vehicle state in the shift process is analyzed: the clutch meshes and the engine output torque is transferred to the wheel according to the dynamics model;The clutch is out,the engine is disconnected from the transmission system,and the vehicle has no power.Therefore,the vehicle dynamics equations are established according to the change of the clutch state in a single shift.Due to the short time and small change of the vehicle speed,it is considered that the external force of the vehicle in this process is unchanged.Based on this,the dynamic equations are solved to obtain the estimated value of the mass in a single shift process.Considering the deviation of the estimation result caused by the difference between the calculated torque and the actual torque of the engine and the influence of noise on the sensor,the recursive least square method(Recursive Least Square,RLS)is used to regression the estimated mass value of the multiple shift process,and the quality estimation algorithm is obtained.(2)The dynamic model of the vehicle by the forward euler method for discretization difference equation,selecting the speed,quality,from bottom slope as state variables,and to establish the state space equation of vehicle through the state space equation of structures,extended kalman filter,the speed,quality estimation results as observed quantity of extended kalman filtering iterative calculation of kalman filtering.The slope estimation algorithm is obtained by observing the slope in state variables.The measurement error covariance R matrix of the extended Kalman filter is obtained by the error analysis of vehicle speed and vehicle mass,and the process noise covariance Q matrix is estimated by the maximum likelihood criterion,so that the extended Kalman filter has certain adaptive ability.(3)The MATLAB/SIMULINK model of the algorithm is built,and saic Hongyan Shijie C500 tractor is used as the test vehicle to complete the road test.The CAN data in the test is recorded as the MATLAB data source to verify the validity of the algorithm.The offline simulation results show that the maximum estimation deviation of vehicle mass is less than 6%.The mean absolute error of ramp estimation is less than 0.5°(4)Algorithm program development,select embedded hardware platform ARM Cortex-A8 development board,operating system for Linux.By analyzing CAN protocol SAE J1939,the general communication of commercial vehicle industry,and combining DBC file to obtain the corresponding analytical format of speed,engine speed,engine output torque,clutch signal and brake signal in CAN bus.A Ui interface is designed to select CAN communication port,port baud rate and CAN data parsing format through the touch screen.In the CAN signal receiving module,start the Canutils process and read the CAN data parsing format in the Ui interface to filter and receive packets.In the quality and slope estimation module,the timer is used to read the analytical data as input for parameter estimation,and it is used as a sub-thread to reduce the lag of Ui interface,and finally the estimation results are fed back to Ui interface.Usb-can tool is used to send real vehicle messages to the development board for program testing,and output drawing analysis to the development board.The results of program running met expectations.