Research On TTR-Based Warning And Anti-Rollover Control System Of Heavy Vehicles

Now in the developed countries, such as the United States and some European countries, the research on roll stability of heavy vehicles and tractor-trailer has been carried on earlier than the domestic and make some notable accomplishment. But it is still a domestic blank as to the earlier rollover warning. In this dissertation, through reviewing lots of foreign papers, the main aim is to study on the problem of roll stability of the tractor semi-trailer and establish a set of rollover warning system and a set of anti-rollover control system based on early warning and anti-rollover control algorithm, to further improve the active safety and reduce the rollover accidents happened of the tractor semi-trailer.Because of the sensitive factors, such as the larger weight of heavy vehicles, as well as its higher mass center and so on, the heavy vehicles have the poor dynamic roll stability. Once encounter the roll instability risks, the skilled driver can succeed to stop the rollover risks by taking the following correct measures, such as slowing the forward velocity by brake, reducing the output of engine power by the throttle, as well as taking the timely steering manipulation to correct the motion pose of the vehicle. However, due to excessive dynamic load transfer of vehicle happened in the drive axis and even the semi-trailer axis induced by the rear application phenomena, it makes the front driver often not sense the impeding rollover risks. Therefore, it is too late to make the driver take appropriate measures to prevent vehicle rollover.In order to reduce heavy truck rollover incidents, not only have the rollover impact factors of the heavy vehicles been considered to further optimize the vehicle structure parameters and to improve its passive safety, but it is also necessary to take active measures to improve the handling stability and avoid the rollover accidents by real-time monitoring, assessment, early warning of the rollover risk factors. Therefore, it is imperative to develop the early warning and active safety control system to timely tell the driver the impending rollover danger Rollover active safety control system.The main research contents and the conclusions are as follows in this dissertation:First, this paper presents a model-based early rollover warning algorithm and a set of anti-rollover LQR control algorithm based on early warning. The model-based early rollover warning algorithm utilize the TruckSim models and early warning reference model to predict the impeding vehicle rollover time in advance and tell the driver the warning signals so that drivers have enough time to take appropriate measures to prevent vehicle rollover, thereby greatly improving the vehicle's active safety performance of the heavy vehicles. As to the anti-rollover LQR control algorithm, the principle is to use the optimal additional yaw moment obtained from the control algorithm and then make it reasonable impose the corresponding wheels by taking the moment distribution methods based on the differential braking for the purpose of reducing the risk of rollover.Second, in order to study whether complexity of the warning preference rollover model or not to be influential factors of early rollover warning, this paper establish the preference models of 3-DOF and 5-DOF for the heavy trucks and correspondingly construct the rollover warning preference models of 5-DOF and 8-DOF for heavy tractor semi-trailer. The conclusions is that the more complex the model, the less precision of the early rollover warning.Finally, in this dissertation four kinds of steering case, such as ramp steering, entering steering, obstacle avoidance steering, and worst steering, have been chosen to take joint simulation in the environment of TruckSim and MatLab softwares. The main aim is to verify the accuracy and reliability of the rollover warning algorithm, as well as to verify the active roll stability after imposing the control algorithm of LQR optional control and differential braking. The simulation results show that the algorithm presented in this paper can effectively reduce the lateral load transfer ratio and actively void the occurrence of rollover accidents.