Research On Anti-rollover Control Algorithm For HEV Bus

Rollovers with a higher fatality rate than any other kinds of traffic accidents, is very harmful to the national economy and personal safety. Various countries have exerted large public concern about the rollover of vehicles and have formulated laws and regulations to improve the anti-rollover performance of vehicles. Lots of researches have been done abroad and buses equipped with corresponding technique have been produced. But the methods the parts manufacturers adopted are different, so the diversity of control effect is very wide. Nowadays, the main methods of anti-rollover used in commercial vehicles are active suspension technology, four-wheel steering technology, differential braking technology and active roll bar device. In the other hands, the researches of anti-rollover done in our country are still at theoretical research stage,and haven't produced related anti-rollover products with perfect technology and reliable performance. So that most commercial vehicles haven't been equipped with anti-rollover system and only luxury vehicles have been equipped with this system produced by foreign manufactuers, furthermore, the overload situation widely existed in road traffic further deteriorate the performance of stability of rollover.Considering the severity of energy crisis and the popularity of hybrid technology, more and more hybrid electric buses are running on the road in many our cities. Compared to the traditional buses, hybrid electric buses system need to add motor system and battery system, what's more, the batteries are always arranged in the top of the vehicle, and as a result, vehicle total mass is increased and the location of mass center is heighten. It makes the anti-rollover performance of hybrid electric buses become worse than ever. At present, most hybrid electric buses at service is urban bus, and because of the low velocity of urban road conditions, the influence of anti-rollover performance on vehicle safety is rather little, and in order to exploit hybrid electric buses market, bus manufacturers home and abroad mainly concentrate on the research and development of hybrid electric buses used on the intercity road on which the bus run in a relatively high speed. According to the FAW Group technical needs of next generation hybrid electric bus, vehicle rollover stability and related anti-rollover control algorithm are studied in this research. Based on the Lyapunov stability theory a model reference adaptive anti-rollover control algorithm is developed, and the methods to estimate the state parameters, such as the location of mass centre of the vehicle, the turning characteristics of vehicles and the angle rate of steer wheel with no driver's control while the vehicle is running in different conditions and trigger and termination conditions of active intervention is investigated. And the research contents in this research are included as follows:(1)The main reasons of the vehicle rollover in different road conditions is analyzed based on the vehicle dynamic characteristics. At the same time, by making use of the vehicle sensor signals ,the vehicle mass location is estimated ,the turning type is distinguished and the trigger and termination conditions corresponding to the active anti-roll control is studied.(2)A model adaptive control algorithm of anti-rollover is developed based on Lyapunov stability theory. The aforementioned algorithm can be used to calculate the braking force and apply the braking force on the corresponding wheels using the executive components such as hi-speed solenoid valve to achieve the purpose of active anti-rollover control.(3)Under the Matlab / Simulink environment, an offline simulation platform for anti-rollover control is built. The rules and laws in various countries and large foreign vehicle manufacturers on vehicle test for rollover characteristics have been studied to analyze the advantages and disadvantages of different dynamic rollover test. And then the effectiveness of the anti-rollover control algorithms in different road conditions is verified(4) The validity of the anti-rollover control algorithm in different road conditions is further verified on the HIL test bench, which is built under the Matlab / xPC environment.