With the vigorous development of the automobile industry, various companies have successively built automobile testing grounds in our country. As the main facility of the automobile test ground, the high-speed ring road generally requires a special geometric design method to provide effective, safe and comfortable operating conditions for the continuous high-speed driving test of the automobile on a relatively limited site. Its technical indicators such as planar surface radius and horizontal super-high far exceed the limitations of highway geometric design technical standards. On the other hand, the curve part of the high-speed ring road is completely different from ordinary roads, and the geometric characteristics of its three-dimensional surface have a great impact on the safety and comfort of vehicles when driving at high speeds. These characteristics of high-speed rings determine that it is of special significance to conduct in-depth and systematic research on the geometric design technology of high-speed rings.
Based on the existing high-speed ring theory, this topic conducts in-depth research on the geometric alignment design and driving comfort index evaluation of high-speed rings. The main results are as follows:
1. After comparing the advantages and disadvantages of McConnell's and Bloss's transition curve design methods, an integral algorithm is introduced to optimize the calculation of McConnell's curve. The McConnell curve and Braus curve are widely used in the geometric design of high-speed rings in currently built or under construction automobile test sites. The McConnell curve is derived based on the comfort index, but its calculation has certain variations; while the Brause curve is closer to the driving trajectory, its geometric expression is clearer. Referring to the derivation formula of Braus curve, the numerical integration algorithm is introduced into the derivation of McConnell curve formula to improve its accuracy and improve its practical application value.
2. A design method for the vertical section of the high-speed ring of "vertical first and then horizontal" is proposed.
3. Introducing the lateral adhesion coefficient μ into the cross-section design of high-speed ring roads makes the vehicle speed distribution more consistent with the actual driving conditions: usually, when designing the cross-section of high-speed ring roads, the influence of the lateral adhesion coefficient μ on the vehicle speed is not considered. However, in actual operation, the existence of the μ value increases the test speed to a certain extent, and the driving comfort index also changes accordingly.
4. Vehicle model analysis software Carsim was used to verify the comfort index. CarSim software is a product of Mechanical Simulation Corp., which mainly studies the driving conditions of vehicles under various road conditions and driving actions. CarSim has a common interface with many software. Integration with other software allows users to run the car's dynamic model in a real-time environment. It not only can analyze the change rules of various sports comfort indicators, but also has more intuitive visual effects.
5. Completed the development of the high-speed loop geometric alignment design program (OTD) to realize the high-speed loop design and mapping function. The high-speed loop geometric alignment design program (OTD) adopts an AutoCAD2005-based development platform and uses Visual Studio. NET as a development tool to carry out secondary development of ObjectARX. It not only gives full play to AutoCAD's complete system openness and rich personalization capabilities, but also makes use of Visual C++ object-oriented development environment and application program interface to truly achieve rapid access to AutoCAD graphics database, and uses entity extended data mechanism to establish internal connection between graphics and data, realizing the entire size and parameter driving mechanism.
This topic has important reference value and popularization and application prospects for the design and construction of similar projects.