本文選題：北斗衛(wèi)星導航　切入點：自動轉向　出處：《江蘇大學》2017年碩士論文

【摘要】：拖拉機輔助駕駛技術是農業(yè)機械自動化與智能化的發(fā)展要求,對實現精準農業(yè)具有重要意義。拖拉機輔助駕駛系統(tǒng)不僅可以減輕駕駛員的工作強度,還可以提高作業(yè)精度和生產效率。本文對拖拉機輔助駕駛技術中自動轉向和路徑跟蹤算法進行了研究,以DF904拖拉機為研究對象,結合北斗衛(wèi)星高精度定位設備,采用PID算法控制實現自動轉向、變論域模糊算法控制實現路徑跟蹤。且通過遺傳算法對PID參數值進行了優(yōu)化,通過仿真和試驗進行了驗證。主要研究工作和結果具體如下:(1)確定了拖拉機自動導航系統(tǒng)的總體方案以及硬件選型,衛(wèi)星導航輔助駕駛系統(tǒng)由路徑跟蹤系統(tǒng)和自動轉向系統(tǒng)兩部分組成。根據這兩個系統(tǒng)的功能要求,分別進行了硬件的選型及集成。(2)自動轉向控制算法設計。通過分析臺架試驗數據,獲得拖拉機轉向數學模型,根據轉向模型,在Matlab環(huán)境下通過遺傳算法確定了合適的PID參數值,并在Matlab/Simulink環(huán)境下進行了轉向仿真試驗,從理論上驗證了采用遺傳算法優(yōu)化PID參數以控制自動轉向的精確性。(3)路徑跟蹤控制算法設計。針對在農田坑洼不平、路面復雜實際狀況下,拖拉機按預定路徑行走時具有較強的非線性和不確定性,以及在路徑偏差較小時會出現控制精度較低等情況,本文在模糊控制的基礎上引入變論域模糊控制理論,利用模糊控制器來動態(tài)改變輸入輸出論域,即在模糊規(guī)則不變的情況下讓初始論域隨輸入的變化而變化,解決了模糊控制在“零點”(偏差很小)附近控制精度低的問題。并且在Matlab/Simulink環(huán)境下進行了路徑跟蹤仿真試驗,仿真結果表明,變論域模糊控制能有效地對拖拉機行駛進行路徑跟蹤。(4)試驗研究。試驗包括臺架試驗和路徑跟蹤試驗。其中臺架試驗分別是在未加任何算法控制下以及采用PID算法控制下進行試驗,通過試驗確定了拖拉機的轉向模型和PID控制下的轉向性能。路徑跟蹤試驗分別為在平坦路面和坑洼路面上,行駛速度為3km/h、4km/h時的直線路徑跟蹤,試驗表明,在平坦路面上橫向位置平均誤差均小于3cm;在坑洼路面上遇障礙偏航后拖拉機能快速、準確地糾正偏差,返回預定路徑。本文完成基于北斗導航的拖拉機輔助駕駛系統(tǒng)的相關研制,并通過仿真和試驗測試了系統(tǒng)的性能。試驗表明,該衛(wèi)星導航輔助駕駛系統(tǒng)可實現拖拉機按預定路徑自動行駛。
[Abstract]:Tractor-assisted driving technology is the development requirement of agricultural machinery automation and intelligence, and it is of great significance to achieve precision agriculture.Tractor-assisted driving system can not only reduce the driver's working intensity, but also improve the working precision and production efficiency.In this paper, the automatic steering and path tracking algorithms in tractor assisted driving technology are studied. Taking DF904 tractor as research object and combining Beidou satellite high precision positioning equipment, PID algorithm control is used to realize automatic steering.Variable domain fuzzy algorithm control to achieve path tracking.The parameters of PID are optimized by genetic algorithm and verified by simulation and experiment.The main research work and results are as follows: 1) the overall scheme and hardware selection of tractor automatic navigation system are determined. The satellite navigation assistant driving system is composed of two parts: path tracking system and automatic steering system.According to the functional requirements of the two systems, the hardware selection and integration. 2) automatic steering control algorithm are designed.The mathematical model of tractor steering is obtained by analyzing the data of bench test. According to the steering model, the appropriate PID parameter value is determined by genetic algorithm in Matlab environment, and the steering simulation test is carried out under Matlab/Simulink environment.The design of path tracking control algorithm using genetic algorithm to optimize PID parameters to control the accuracy of automatic steering is theoretically verified.In view of the fact that the tractor has strong nonlinearity and uncertainty when walking according to the predetermined path under the condition of uneven farmland potholes and complicated road surface, and the control precision will be low when the path deviation is small, etc.In this paper, the variable domain fuzzy control theory is introduced on the basis of fuzzy control, and the fuzzy controller is used to dynamically change the input and output domain, that is to say, the initial domain changes with the change of input when the fuzzy rules are invariant.The problem of low precision of fuzzy control near "zero" (small deviation) is solved.The simulation results of path tracking in Matlab/Simulink environment show that variable theory field fuzzy control can effectively track the path of tractor.The test includes bench test and path tracking test.The bench test is carried out under the control of no algorithm and the control of PID algorithm respectively. The steering model of tractor and the steering performance under PID control are determined by test.The path tracking tests are linear path tracking at a speed of 3 km / h and 4 km / h on flat and pothole pavement, respectively. The test results show that,The average lateral position error on the flat pavement is less than 3 cm, and the tractor can correct the deviation quickly and accurately and return to the predetermined path after yawing on the pothole pavement.In this paper, the development of tractor assisted driving system based on Beidou navigation is completed, and the performance of the system is tested by simulation and test.The test results show that the satellite navigation aided driving system can automatically drive the tractor according to the predetermined path.
【學位授予單位】：江蘇大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：S219

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