电动拖拉机底盘多目标优化设计
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摘要
针对目前电动拖拉机底盘布置研究相对较少的情况,基于现有的整机匹配结果进行了底盘布置设计,利用三维建模软件建立模型,输入质量参数,提取整机主要零部件重心位置参数,然后通过分析拖拉机牵引机组作业时的力学特性,建立相关数学模型。以电动拖拉机的牵引效率和整机质量作为优化目标,采用NSGA-Ⅱ算法进行多目标优化。综合考虑了犁耕作业下拖拉机的稳定性要求、驱动力要求、载荷波动情况以及传动系和行走系零件寿命等影响因素,制定了算法运行的约束条件,建立了约束方程组。以电动拖拉机的使用重力、前后电池组的质心和整机质心为目标变量,推导出动力性和经济性最优的目标函数。通过ModeFRONTIER平台,采用NSGA-Ⅱ算法对电池分布式方案进行了多目标优化。两种不同耕深条件下的优化结果对比分析表明,按照本文方式优化布置后的电动拖拉机在耕深为180 mm时,优化后的整体质量与经验法相比减少了14. 3%,配重质量为25. 3 kg;耕深为240 mm时,优化后的整体质量与经验法相比减少了10. 3%,配重质量仅为4. 4 kg,说明在牵引工况下无需额外增加配重就能达到良好的牵引性能。与经验法相比,两种耕深条件下拖拉机的配重都小很多,说明基于传统拖拉机的配重经验法计算并不适用于电动拖拉机,同时也能说明,电动拖拉机因自身总质量超过同功率段传统拖拉机,可以通过合理设计底盘布置方案,在没有配重的情况下达到理想的牵引效率。优化后的电动拖拉机底盘布置方案,在作业工况下驱动轮滑转率小于特征滑转率,整机牵引效率明显提高。
In view of the relatively few researches on the chassis layout of electric tractor,the chassis layout design was carried out based on the matching results of the whole machine. The model was established by using 3 D modeling software,and the center of gravity parameters of main parts of whole machine was extracted. Then,by analyzing the mechanical characteristics of tractor traction unit,a mathematical model was established. Taking the traction efficiency of the electric tractor and weight of the whole machine as the optimization objective,the NSGA-Ⅱ algorithm was used for multi-objective optimization. The influence factors of tractor's stability,driving force,load fluctuation and life of drive system and walking system parts were considered as the constraint conditions of the algorithm. The constraint equations were set up. The gravity function of the electric tractor,centroid of front and rear battery packs and centroid of the whole machine were taken as the target variables,and the objective function of optimal power and economy was derived. Through the Mode FRONTIER platform,the NSGA-Ⅱalgorithm was used to optimize the battery distribution. The results of the optimization under two different tillage depth conditions were compared and analyzed. It was found that when the tillage depth was180 mm,the overall weight of the optimized electric tractor was reduced by 14. 3% compared with theweight of experience method,and the counterweight was only 25. 3 kg. When the tillage depth was240 mm,the overall weight of the electric tractor was reduced by 10. 3% compared with the weight of experience method,and the counterweight was only 4. 4 kg. The results showed that the empirical method based on traditional tractor was not suitable for electric tractors. Under the working conditions,the driving wheel slip ratio of the optimized electric tractor was less than the characteristic slip ratio,and the traction efficiency of the whole machine was obviously improved.
In view of the relatively few researches on the chassis layout of electric tractor,the chassis layout design was carried out based on the matching results of the whole machine. The model was established by using 3 D modeling software,and the center of gravity parameters of main parts of whole machine was extracted. Then,by analyzing the mechanical characteristics of tractor traction unit,a mathematical model was established. Taking the traction efficiency of the electric tractor and weight of the whole machine as the optimization objective,the NSGA-Ⅱ algorithm was used for multi-objective optimization. The influence factors of tractor's stability,driving force,load fluctuation and life of drive system and walking system parts were considered as the constraint conditions of the algorithm. The constraint equations were set up. The gravity function of the electric tractor,centroid of front and rear battery packs and centroid of the whole machine were taken as the target variables,and the objective function of optimal power and economy was derived. Through the Mode FRONTIER platform,the NSGA-Ⅱalgorithm was used to optimize the battery distribution. The results of the optimization under two different tillage depth conditions were compared and analyzed. It was found that when the tillage depth was180 mm,the overall weight of the optimized electric tractor was reduced by 14. 3% compared with theweight of experience method,and the counterweight was only 25. 3 kg. When the tillage depth was240 mm,the overall weight of the electric tractor was reduced by 10. 3% compared with the weight of experience method,and the counterweight was only 4. 4 kg. The results showed that the empirical method based on traditional tractor was not suitable for electric tractors. Under the working conditions,the driving wheel slip ratio of the optimized electric tractor was less than the characteristic slip ratio,and the traction efficiency of the whole machine was obviously improved.
引文
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15 TONDJI Y,BOTEZ R.Semi-empirical estimation and experimental validation of the mass and the center of gravity location of the unmanned aerial system-uas-s4 of hydra technologies[C]∥International Conference on Unmanned Aircraft Systems(ICUAS),2016:1319-1326.
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18彭旭东,周受钦,谢友柏,等.汽车轮胎磨损机理的研究[J].润滑与密封,1999(6):50-52.PENG Xudong,ZHOU Shouqin,XIE Youbai,et al.Study on wear mechanisms for automobile tires[J].Lubrication Engineering,1999(6):50-52.(in Chinese)
19刘孟楠,周志立,徐立友,等.基于多性能目标的拖拉机运输机组优化设计[J].农业工程学报,2017,33(8):62-68.LIU Mengnan,ZHOU Zhili,XU Liyou,et al.Multi-objective optimization and design of tractor trailer systems[J].Transactions of the CSAE,2017,33(8):62-68.(in Chinese)
20刘孟楠.基于NSGA-Ⅱ算法的悬挂机组拖拉机配重方案优化[C]∥第十一届河南省汽车工程科技学术研讨会论文集,2014:20-23.
21徐立友,李晴,周志立.一种改进遗传算法在离合器参数优化中的应用[J].中国机械工程,2015,26(24):3307-3311,3317.XU Liyou,LI Qing,ZHOU Zhili.An improved genetic algorithm and its applications in clutch parameter optimization[J].China Mechanical Engineering,2015,26(24):3307-3311,3317.(in Chinese)
22潘金坤.基于mode FRONTIER的离合器碟形弹簧多目标优化设计[J].机械传动,2011(2):24-27.PAN Jinkun.Multi-objective optimal design of disc spring in clutch based on mode FRONTIER[J].Journal of Mechanical Transmission,2011(2):24-27.(in Chinese)
23张文春,方在华.理论牵引特性曲线数学模型及计算机作图程序[J].拖拉机,1987(5):23-28.
2 KIRSCH D.History of the electric automobile:battery-only powered cars[J].Technology and Culture,1995(3):710-712.
3 XU L Y,ZHANG X R,ZHU S M,et al.Driving system design for greenhouse electric tractor[C]∥International Conference on Computer Science and Environmental Engineering(CSEE),2015:1187-1194.
4 CARLIN M,ABENAVOLI R I,KORMANSKI H,et al.A hybrid electric propulsion system for a forestvehicle[C].Energy Conversion Engineering Conference,Honolulu:IECEC,1997:2019-2023.
5 BODRIA L,FIALA M.Design and testing of an electric powered walking tractor[J].J.Agric.Eng.Res.,1995,60(1):57-62.
6 WU Shufang,WANG Zongyan,WANG Yi,et al.Based on topology optimization method the cab mount bracket lightweight design[J].Trans Tech Publications,2012,152-154:1292-1297.
7 KIM J,PARK Y.Analysis of agricultural working load experiments for reduction gear ratio design of an electric tractor powertrain[J].Transactions of KSAE,2012,20(5):138-144.
8 MOUSAZADEH H,KEYHANI A,JAVADI A,et al.Life-cycle assessment of a solar assist plug-in hybrid electric tractor(SAPHT)in comparison with a conventional tractor[J].Energy Conversion and Management,2011,52(3):1700-1710.
9刘孟楠,徐立友,周志立,等.增程式电动拖拉机及其旋耕机组仿真平台开发[J].中国机械工程,2016,27(3):413-419.LIU Mengnan,XU Liyou,ZHOU Zhili,et al.Establishment of extended range electric tractor and its rotary cultivator's simulative platforms[J].China Mechanical Engineering,2016,27(3):413-419.(in Chinese)
10周志立,夏先文,徐立友.电动拖拉机驱动系统设计[J].河南科技大学学报(自然科学版),2015,36(5):78-81,86.
11徐立友,刘孟楠,周志立.串联式混合动力拖拉机驱动系设计[J].农业工程学报,2014,30(9):11-18.XU Liyou,LIU Mengnan,ZHOU Zhili.Design of drive system for series hybrid electric tractor[J].Transactions of the CSAE,2014,30(9):11-18.(in Chinese)
12 ABDOLMALEKI H,JAFARI A,TABATABAEIFAR A,et al.Development and evaluation of an in-situ tire testing facility with variable side slip angles[J].Journal of Terramechanics,2015,59:49-58.
13周志立,方在华,赵铨.拖拉机-农具机组牵引性能的计算机辅助分析[J].农业机械学报,1991,22(4):7-14.
14王宣锋,梁迎春,黄朝胜,等.超静定多轴牵引车制动试验载荷参数的优化[J].吉林大学学报(工学版),2011,41(2):316-320.WANG Xuanfeng,LIANG Yingchun,HUANG Chaosheng,et al.Load parameter optimization of brake test on statically indeterminate multi-axle tractor[J].Journal of Jilin University(Engineering and Technology Edition),2011,41(2):316-320.(in Chinese)
15 TONDJI Y,BOTEZ R.Semi-empirical estimation and experimental validation of the mass and the center of gravity location of the unmanned aerial system-uas-s4 of hydra technologies[C]∥International Conference on Unmanned Aircraft Systems(ICUAS),2016:1319-1326.
16董保利,左曙光,吴旭东.轮胎均匀磨损建模与仿真[J].计算机仿真,2009,26(2):274-277.DONG Baoli,ZUO Shuguang,WU Xudong.Modeling and simulation of even tire wear[J].Computer Simulation,2009,26(2):274-277.(in Chinese)
17胡伟,温旭辉,刘钧.电动汽车电机驱动系统寿命模型[J].电机与控制学报,2008,12(6):670-674.HU Wei,WEN Xuhui,LIU Jun.Life time model of motor drive system for electric vehicles[J].Electric Machines and Control,2008,12(6):670-674.(in Chinese)
18彭旭东,周受钦,谢友柏,等.汽车轮胎磨损机理的研究[J].润滑与密封,1999(6):50-52.PENG Xudong,ZHOU Shouqin,XIE Youbai,et al.Study on wear mechanisms for automobile tires[J].Lubrication Engineering,1999(6):50-52.(in Chinese)
19刘孟楠,周志立,徐立友,等.基于多性能目标的拖拉机运输机组优化设计[J].农业工程学报,2017,33(8):62-68.LIU Mengnan,ZHOU Zhili,XU Liyou,et al.Multi-objective optimization and design of tractor trailer systems[J].Transactions of the CSAE,2017,33(8):62-68.(in Chinese)
20刘孟楠.基于NSGA-Ⅱ算法的悬挂机组拖拉机配重方案优化[C]∥第十一届河南省汽车工程科技学术研讨会论文集,2014:20-23.
21徐立友,李晴,周志立.一种改进遗传算法在离合器参数优化中的应用[J].中国机械工程,2015,26(24):3307-3311,3317.XU Liyou,LI Qing,ZHOU Zhili.An improved genetic algorithm and its applications in clutch parameter optimization[J].China Mechanical Engineering,2015,26(24):3307-3311,3317.(in Chinese)
22潘金坤.基于mode FRONTIER的离合器碟形弹簧多目标优化设计[J].机械传动,2011(2):24-27.PAN Jinkun.Multi-objective optimal design of disc spring in clutch based on mode FRONTIER[J].Journal of Mechanical Transmission,2011(2):24-27.(in Chinese)
23张文春,方在华.理论牵引特性曲线数学模型及计算机作图程序[J].拖拉机,1987(5):23-28.