Research On Roll Stability Control Of Liquid Tank Semi-trailer

As an efficient and inexpensive means of transport,it has become the principal part of dangerous goods in road transportation.But,in contrast with else semi-dragging trucks,its gravity center position is higher,weight and volume are bigger.At the same time,tractor has the coupling relationship with trailer.In addition,liquid sloshing also has the coupling relationship with vehicle motion.In the process of turning or emergency obstacle avoidance,the semi-trailer tank truck easily happens rollover,shimmies and folding accidents.Because liquid cargo generally has the characteristics of flammable,explosive and toxic,once having accidents,it is easy to cause the leakage,combustion and explosion of liquid products,what’s more,it causes not only heavy casualties and property losses,but also ecological disaster.In the design stage of the tank,engineers design swash plate to prevent the liquid sloshing,the stability of tank cargo has been studied extensively through optimizing the internal structure and shape of tank,a large number of theoretical,numerical and experimental were done to verify the effectiveness of the proposed design scheme,however the determined tank shape cannot reduce instability under the filling ratio variation、specific conditions and the different unstability conditions at the same time.Therefore,it is a more effective and widely adaptive way to control the stability of the tank vehicle through active safety control.Based on the basic equations of fluid dynamics and boundary conditions of liquid sloshing,the control equation of liquid sloshing in rigid tank body is established in this paper,reference the analysis of liquid fuel sloshing in spacecraft of previous study;then using Rayleigh Ritz method to solve the functional problems,the characteristic frequency and characteristic mode of liquid sloshing are determined,the force function and wave height mode function are solved,in the end,the inertial force and the dynamic force of the force sloshing mode are solved.The influence factors affecting the inertia force and the dynamic force are analyzed,establishing vehicle-liquid coupling model,analyzing the influence of liquid shake on stability of tank car,the stability control system took the tractor’s and semi-trailer’s yaw rate,side slip angle as control variables,three freedom degress model of semi-dragging truck as reference model,the additional yaw moment is calculated based on LQR control theory and the differential braking strategy is laid down through the analysis of the lateral stability of the semi-trailer tank truck.In different working conditions of step steering and fishhook steering,simulation research on the stability control is done.The simulation result indicates: the stability control system designed by the dissertation can improve the roll stability and yaw stability of liquid tank semi-trailer,reduce rollover accidents.