Research On Objective Evaluation Of Handling And Stability Of Heavy Commercial Vehicles

In recent years our domestic automobile industry has developed rapidly. But own-brand heavy commercial vehicle enterprises due to their weak foundation of research and development, product performance and brand awareness are not as foreign brands, occupy mostly low-end market. Therefore, how to improve product performance, enhance the competitiveness of the enterprises have been imminent.How to develop a high-performance vehicle is of great significance. Since the chassis performance is crucial to vehicle, the main performance of automobile chassis in the early design stages must be ensured.But in the modern chassis development, higher performance are requirements, in crucial conditions and the high-frequency response, the drive, brake, steering, suspension assembly interaction and mutual influence, separate evaluations on the various assemblies can not meet the need. Hence, we must conduct comprehensive performance evaluation to vehicles to meet matching requirements. However, we have not yet got an effective integrity of the objective evaluation method and system.Therefore it's urgently to establish an objective evaluation system based on the assembly of virtual prototype technology which can optimize and match automobile dynamic performance in the conceptual design stage of new vehicle development. This objective evaluation of the indicators must be able to identify a comprehensive inspection of vehicle dynamics.In the whole design stages of heavy commercial vehicle of our country, all of the heavy commercial vehicle enterprises concentrated on the development of various assemblies'fatures but not on vehicle performance due to their weak foundation of research and limited by their technology. Some manufacturers even maked a limited studying, they can not make the corresponding changes based on the evaluation results of the car. Therefore the inaccuration in the early stages of the objective of will directly affect vehicle performance, especially the performance at full load, complex conditions. If you do not have a comprehensive, scientific, objective evaluation system, can not match the standard, can not really grasp the matching technology of chassis, can not develop the high-quality heavy-duty commercial vehicles, the domestic commercial vehicle manufacturers also do not have their own core competitiveness.With the sustained and rapid development of the national economy, auto transport vehicles showing a high-speed, non-professional drivers, car-intensive tendency, and in particular, heavy commercial vehicles are more and more load, and the sharp increase in traffic accidents require vehicle must have good active safety in order to effectively suppress the occurrence of traffic accidents. Referred to as "the lifeblood of high-speed vehicles," the vehicle handling and stability are one of the main performances which imfects its active safety. As a nature of its own, vehicle handling and stability is not including the performance of the drivers. Open-loop test methods are considering a vehicle as a control system, analysising and studying the characteristics of cars in accordance with the general requirements of the system's quality control, transient response characteristics. Study on the characteristics of vehicle open-loop system using only an objective evaluation method, that is, to determine the objective evaluation index system in accordance with the principles of heavy commercial vehicle dynamics at first, and then do real vehicle tests, through the test apparatus to measure the physical characterization of the vehicles (such as: yaw rate, lateral acceleration, roll angle, etc.) to evaluate the car's handling and stability. Therefore, the real vehicle test is also the principal means to do the objective evaluation of handling and stability of heavy commercial vehicles in this article. Including the main contents of the thesis is as follows:First of all, collect the information of objective evaluation method of heavy-duty commercial vehicle's handling and stability in research companies and research units at home and abroad. Learn the status quo on the evaluation of the handling and stability of heavy vehicles, and study the previous research ideas, in order to determine the foundation for an objective evaluation system. Then sum up the domestic and foreign enterprises and research units'methods of objective evaluation of handling and stability, combined with theoretical analysis and relevant laws and regulations, as well as the selecting method of objective evaluation indicators of passenger handling and stability, so as to obtain the most scientific index system. For heavy commercial vehicles, we emphasis on the analysising of the differences of handling dynamics compared with the passenger cars; and for heavy-duty semi-trailer, we emphasis on the analysising of the differences of handling dynamics compared with heavy commercial vehicles. Evaluation methods, including how to select operating mode, the driver how to operate, parameters which required to measure and so on, and briefly explain the dynamics theory of the indicators selecting or the main factors.Then, do real vehicle test based on the selected indicators and test methods and collecte the test data. Here, for heavy commercial vehicles,we did the other 10 tests in addition to turning a motorcycle brake test; and for heavy-duty semi-trailer, due to the difficulty of the test and the limits of the conditions,can not be do real vehicle test.So we used the software Trucksim in the simulation analysis of vehicle, and recorded the data.Finally, the data processing of the vehicle's handling and stability test results is a very complex job.In particular, there is a variety of non-ideal data to increase data processing more difficult. Therefore, for each evaluation target, we studied a number of data-processing algorithms, and written some programs to reduce the complexity and difficulty of the data processing.