双层公交客车转向系设计开题报告

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1. 研究目的与意义（文献综述）

after entering the new century, china'sautomobile industry has developed rapidly. china has become the world's largestautomobile production and sales country, and the automobile manufacturingindustry has also become an important economic pillar related to nationaleconomy and people's livelihood. with the economic development and theimprovement of people's living standards, people's requirements for carhandling stability and riding comfort have gradually increased. at the sametime, with the popularization of the concept of green travel, buses have becomethe choice of many people, and the steering system, which is an importantfactor affecting the stability of bus handling, also needs to be morerationally and accurately optimized. the graduation design will take intoaccount both theoretical requirements and actual conditions to design andoptimize the steering system of double-decker buses.

the car steering mechanism is arelatively complicated space mechanism, which is a mechanism to ensure that thevehicle moves along the trajectory by reasonably matching the different anglesof the left and right steering wheels. the design requirements of theautomobile steering system can ensure that the car has high maneuverability;the coordination between the kinematics and the mechanical relationship betweenthe steering wheel and the corners of each steering wheel should be guaranteed;at the same time, the movement of the steering transmission mechanism and thesuspension steering device interfere should be minimal.

in china, many scholars in theautomotive industry have published articles on the latest research status ofsteering systems in journals, which have great guiding significance andreference value for steering systems. fang zhigang et al. used ahigh-precision, simple-to-calculate plane analysis method to optimize thesteering trapezoidal mechanism of a small van. the actual difference betweenthe trapezoidal corner difference and the ackerman corner difference wasoptimized by using the matlab optimization toolbox for the steering system ofthis minivan ^[1]. zhang jun et al. proposedthe concept of ideal steering trapezoid based on the typical integral steeringmechanism based on the shortcomings of the existing steering theory ofautomobiles, and established a mathematical model of ideal steering trapezoid.the deviation of the tie rod of the steering mechanism was taken as theoptimization target. a better parameter combination was obtained by optimizingthe actual vehicle parameters. it was verified that the unit of length was usedas the evaluation basis for the steering trapezoidal mechanism check^[2]. xuruiliang et al. introduced the recursive error function expression of theturning trapezoidal mechanism through theoretical analysis and calculation, determinedthe optimal objective function with the error squared sum as the minimum, andproposed the idea of using the probability density function as the weightingcoefficient function. as an example, the orthogonality method is used to studythe change law of the objective function, and the least square method of matlabis used to solve the optimization function^[3]. shisujuan et al. simulated annealing algorithm and local optimization algorithmbased on μ-1 law, getting rid of the problem of local optimal solution due toinappropriate initial value selection, and obtained the global optimal solution^[4]. liuling et al. established the nonlinear optimization model of the steeringtrapezoidal mechanism, and then introduced the out-of-bounds detection functionto improve the traditional particle swarm optimization algorithm, and gave amethod for solving the nonlinear optimization model of the steering trapezoidalmechanism. implementation procedures^[5]. zhou bing et al. used adamssoftware to establish a virtual prototype model of macpherson suspensionsteering mechanism, and analyzed the influence of key points in the steeringmechanism on ackerman steering characteristics and wheel toe angle changes ^[6]. xiang tiemingetal. used the steeringtrapezoidal base angle and trapezoidal arm length as design variables, and tookthe minimum cumulative relative deviation of the actual turning angle of theouter wheel and the ideal turning angle as the objective function. using matlabsoftware as an optimization design tool, optimize design^[7]。

2. 研究的基本内容与方案

using the library and networkresources in the school, through consulting relevant literature, under theguidance of the teacher, according to the development process of thedouble-decker bus steering system, comprehensive practical applications andoptimization choices were made to analyze the steering system design. whendesigning experience, you need to choose the steering system, includingmechanical steering system, hydraulic power steering system, electro-hydraulicpower steering system, electric power steering system, and steer-by-wiresystem. with the development of steering technology, great changes have alsotaken place in steering gear. currently, there are four main types of steeringgears: worm finger type, worm roller type, recirculating ball type and rack andpinion type. this design chose electric power steering system, rack and pinionsteering gear.

（1）read relevant literature to understand themain contents of the design of passenger car steering system, understand thecurrent progress of domestic and foreign research on the design andoptimization of automotive steering system and the current technicaldifficulties, and determine the steps of this steering system design.

3. 研究计划与安排

（1）graduationdesign presentation (2019.12.23): understand the requirements of graduationdesign, time node.

（2）graduationdesign preparation week (2019.12.26-2020.1.10): determine graduation project topics,orientation, collect materials and foreign language translation materials todetermine graduation project topics, improve graduation design task books(relevant parameters), and collect data inside and outside the school.

（3）winterholiday (2020.1.11-2.23): read the literature, install and learn relatedsoftware.

4. 参考文献（12篇以上）

[1] fangzhigang, guo xuexun, wang bin, xu guanneng. optimization of integrated steeringtrapezium mechanism [j] .beijing automobile, 2010 (06): 39-42.

[2] zhangjun, li enke, wang wei, qu xiang, liao linqing.study on trapezoidal trap andoptimization of tie rods for automobiles.

[3] xuruiliang, cao qingmei.parameter optimization of vehicle steering trapeziummechanism [j] .tractor and agricultural transport vehicle, 2008 (01): 38-40.