| With the rapid development of the logistics industry and the highway, tractor semi-trailer with its large carrying capacity, relatively low transportation cost has become one of the main types of highway transportation. However, due to the higher tractor semi-trailer centroid location, narrow wheelbase relative to the body and a series of features, its rolling stability is poor so that tractor semi-trailer is prone to rollover which is very dangerous; therefore, how to timely inform the driver of the vehicle rollover risk and control of the vehicle in the situation of the risk, becomes an effective way to solve the semi-trailer rollover problem.Aiming at the problem of rollover stability of tractor semi-trailer, this paper mainly studied the following aspects:Firstly, in this paper, on the basis of reading a large number of domestic and foreign literatures, rollover stability mechanism of the tractor semi-trailer and the factors affecting the stability of rollover are analyzed, which determines the method of improving the roll stability of tractor semi-trailer: On the one hand, using the rollover warning technology to remind the driver of dangerous driving behavior; on the other hand, using active anti-roll bars to control the dangerous situation which is too late for the driver to make an efficient operation.Secondly, this paper established the nine degrees of freedom rigid body tractor semi-trailer prediction models that can reflect the yaw-roll motion, and the professional simulation software Trucksim was used to validation the proposed model. Using the established nine degrees of freedom model as a rollover warning reference model, taking the lateral load transfer rates as indicators of tractor semi-trailer rollover, the TTR rollover warning algorithm was introduced, which can predict the rollover dangerous state of the tractor semi-trailer in a super real-time, and the accuracy is validated by simulation under different conditions.Finally, in order to reduce operational burdens and to further improve the rolling stability of the vehicle, the method for the semi-trailer axle to install active anti-roll bars was proposed to improve its rolling stability, and the optimal control moment was obtained by using the extended linear quadratic state regulator, then the simulation analysis under double lane conditions was conducted to validate the effectiveness of the control method. In terms of the shortcomings of continuous control system, e.g. high energy consumption and short life, an anti-rollover control strategy based on TTR warnings was proposed for achieving the intermittent control and its controlled results were compared to that with continuous control. The compared results demonstrate that the anti-rollover control warning strategy under TTR warnings developed in this research not only can effectively improve the roll stability of tractor vehicles, with energy saved,but also prolong the life of the anti-rollover device. |
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