Roll Control Of Tractor Semi-Trailer Based On Kalman Filter

Tractor semi-trailer is composed of tractor and semi-trailer. Comparing with other common truck, it has a lot of advantages and plays an important role in modern road transport. But because of its large mass, high center of gravity, its rollover accident is easily to occur. So it is extremely important to improve the roll stability of tractor semi-trailer. The timely and exact information of the vehicle state is essential to safe control, but because of various limitations, some vehicle state variables can’t measured directly or have high measurement cost.This dissertation around state monitoring and roll control of tractor semi-trailer, mainly researched the state estimation based on Kalman filter theory and the strategy of tractor semi-trailer roll control:At first, a7-DOF dynamic model of tractor semi-trailer was established, and a simulation model with the Matlab/Simulink software was established too. Based on the model, a state estimator based on Kalman theory was designed, using easily measured parameters to estimate the parameters that are difficultly measured or have high measurement cost, after that, compared estimated values and simulation measurements and analyzed the influence with changes of process noise covariance Q and measurement noise covariance R. The results showed that Q and R have great effect on estimate accuracy of Kalman filter. So, this dissertation presented a optimization method based on Simulink Response Optimization to optimize Q and R, this method could solve the problem of noise measurement and improved the estimation accuracy of Kalman filter.Then, a fuzzy PID controller was designed to control the roll of tractor semi-trailer. Aiming the complexity of usual methods to setting PID controller parameters, presented using Matlab optimization function to setting PID parameters, this method provided a more convenient and effective way for the selection of PID parameters. This fuzzy PID controller controlled the roll angle to a certain range based the roll angle estimated by Kalman filter. The results showed that this fuzzy PID control strategy could improve the roll stability of tractor semi-trailer effectively.At present, the soft measurement technology based on Kalman filter and the active suspension based on fuzzy PID control are rarely used in tractor semi-trailer. This dissertation estimated the driving state of tractor semi-trailer which are difficultly measured or have high measurement cost using Kalman filter theory, which could greatly reduce the measurement and control cost. In addition, the trend of rollover could be forecasted based the measurement, then the control device could intervence timely to prevent rollover accident which caused by the oversize roll angle.