Research On Improved TTR Rollover Warning And Multi-objective Stability Control Algorithm Of Heavy Duty Vehicle

With the development of highway, the road transportation industry flourishes based on heavy duty vehicle. The wide application of heavy duty vehicle improves the efficiency of road transportation and reduces the cost of goods-delivery. While the heavy duty vehicle has a higher gravity-center, larger loads and relatively narrow tread in comparison with the height of vehicle. Therefore the stability of rollover threshold is lower, consequently, rollover tends to occur.Simultaneously, and there exists a complicated coupling relationship between the tractor and semitrailer, which causes occurrence of rollover, swing, and jackknife. For years the accidents of heavy vehicles are in a status of high frequency, and how to solve the problem of steability and safety of heavy duty vehicle has become a key factor in road development.The present research conducted by national research center and factories mostly focused on static stability mechasim analysise and simulation, while the technique of dynamic stability control is inadequate, further more, there is a blank in the rollover warning and stability control of heavy duty vehicle. This paper, firstly, based on the latest foundings home and abroad, made a research into the rollover warning and stability control technique, with a focus on the precise construction of warning and control model, and realization of dynamic rollover warning and robust stability control in disturbance. Secondly, as for semitraler, to solve the problem of rollover, swing and jackknife, this paper explored a set of multi-objective contrl strategy so as to ahieve comprehensive control over rollover, swing and jackknife. And thirdly, taking the above research as a basis, it independently developed rollover warning controller, constructed on-line platform for real vehicle rollover test, and the real vehicle tests were conducted to testify the conrol effect.According to the above technical route, the paper explored the following discussions. First of all, a dynamic model was built.The paper first built up a 3-DOF model and then utilized off-line identification technology, and explored to identify the key parameters of 3-DOF vehicle model.In addition, using the improved model to carry out on-line rollover prediction and control, the dynamic rollover threat could be precisely predicted. This alglorithm of vehicle rollover warning was characterized with simplicity, good real-time and convenient transplantation. In order to make the model closer to the real vehicle, the data obtained from real vehicle tests can be used to set the key parameters of the model. The modified model can precisely predict the risk degree of rollover which prepared a model basis for the later control technique.Secondly, rollover warning alglorithm of vehicle was developed. Using the alglorithm based on the dynamic rollover time, this research aimed to early warn the risk of rollover. Grounding on the reference rollover model, choosing the absolute value of lateral load transfer as the threshold of rollover, judging from the current vehicle status, it managed to predict in the coming three seconds whether the lateral load transfer reached the rollover threshold and got a real time TTR(Time to rollover). And then, according to predicting value, it triggerd the predicting device (buzzers and alarm lights) which reminded the driver to slow down and modify his driving, so as to avoid the potential hazards.Thirdly, rollover stability control alglorithm of vehicle was developed. It targeted at the design of robust controller to improve the stability control of heavy duty vehicle, the core of which was that the rollover accidents could be avoided by differential braking on the basis of robust feedback gain control. In this way the question of rollover stability control was transformed into robust interference restraint through H∞state feedback control. And then, taking the lateral load transfer as the control target, it designed a H∞state feedback controller and a PID controller. Next, utilizing the commercial software Trucksim as vehicle sophisticated model, it simulated the rollover stability control in open-loop and human-vehicle close loop situation. The simulation result proved that the LMI robust controller could effectively improve the vehicle rollover stability and has the better interference immunity and robustness. Fourthly, based on LQR control, multi-objective control strategy was studied. In regard to the properties of semitrailer and exsisting question, it built up the dynamic model with which the LQR control, multi-objective control strategy was explored through differential braking and improved the comprehensive control of rollover, swing, and jackknife stability of heavy duty vehicle and semitrailer. Simulation results showed that above control strategy could effectively improve the vehicle driving stability; avoid the occurrence of rollover, swing and jackknife.At last, the rollover warning control alglorithm of vehicle was tested on real vehicle. Grounding on the simulation results, it developed the heavy duty vehicle rollover warning test platform including sensors, data collecting system, warning controller and warning device. And utilizing the platform, the heavy duty vehicle rollover prediction and control tests were conducted on real vehicle. The tests results showed that the platform reached the expectant objective and could meet the demand of rollover prediction and control; and the rollover warning controller designed independently could effectively predict the risk degree of rollover. Furthermore, the controller was original and supplied a gap in the field of heavy duty vehicle active safety control which provided a guideline for the domestic manufacturers and research centers.In general, the paper firstly made an analysis on the heavy duty vehicle stability mechanism and put forward the technique scheme and route on the basis of latest research foundings home and abroad. And secondly it developed rollover warning and stability control alglorithm of vehicle which was conformed simulation results and could effectively improve the stability of rollover, swing and jackknife. Finally, it developed the heavy duty vehicle rollover warning test platform and the real vehicle tests were carried out on an airport of air force, and the rollover warning controller designed independently could effectively predict the rollover risk and warned the driver to modify his driving, so as to avoid the occurrence of rollover.?...