一个树状多支结构模型式程序的线性运动——主动喷雾喷洒机的设计外文文献翻译、中英文翻译
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一个树状多支结构模型式程序的线性运动主动喷雾喷洒机的设计农业工程处,Kardinaal Mercierlaan 92,3001比利时鲁汶 摘要文件的第一部分,一个多体系统的运动线性方程已经确立。在这一部分, 这种方法是被用作计算由10个部分组成的喷涂机的运动计算方程的。吏罗拉式 是轮胎是典型的轮胎。给确定低通滤波品质的轮胎长度轮胎接触地面也被考虑。 通过一个直接承袭于多体模型的更小的示范模型,在一个带回路恢复功能的高斯 线性二次法的帮助下悬浮式喷雾设计出来。液压驱动拖拉机通过在对面旋转喷雾 吊杆来抵消拖拉机的意外旋转,这样喷嘴与田间作物间的距离仍然在可接受的范 围内。在模拟实验中,通过在规范化轨道上驾驶喷雾机,有偿和无偿喷雾吊杆运 动产生,并相应压缩了的部分喷雾产生。符号Ac 气缸净面积平方米Cd 因次流量系数-G 真实植物模型 GO 象征植物模型 Ga 非确定结构化添加剂 Gm 非确定结 构化添加剂HOO 卡尔曼滤波器及被评估的植物输出的开环传递 矩阵(=环路 增益,回报率)HOS 卡尔曼滤波的开环传递矩阵1.引言农业生产遭受严重的由昆虫,杂草和病虫害带来的损失。由于世界人口的成 倍增长,作物保护已成为世界上最重要的学科领域,用以提高生产力和作物产 量。传统的植保分类方法分为五类:化学、生物、农艺、机械、生物物理技术1。 化学防治方法目前最常使用。因为其特有的高效率,操作的简单性以及宽广的范 围:除草剂、杀虫剂可使用同一机器。这些化学物质溶解于液 体载体由拖拉机带动的喷雾吊杆进行大面积喷洒。目前倾向于使用浓缩剂喷洒(小喷量技术),化学药剂的成本上升,化学污 染的日益严重需要更精密的,尽可能在大面积土地均匀喷洒液体的喷洒机械的出 现。喷雾方式的不当主要是由于不同的水力设备之间的压力、喷嘴糟糕的状况、 驾驶拖拉机时速度不均、风况,最后也是很重要的,喷杆在垂直方向的无用的震 动偏移。由于土地状况所引起的拖拉机车身的不平衡导致了喷杆的不良动作,直 接导致农作物和喷嘴之间的垂直距离不断改变,导致了不规则分布喷雾的现象.。 当工作速度较髙,使农业机械的使用更剧烈、,震荡现象更加明显,如果土地状 况恶劣,拖拉机的影响更大。所有这些负面效应将加大阐述喷雾模型参数的难度。2显然,补偿无用的喷杆移动是比以往更加有趣和具有挑战性的研究领域。此外,,提供稳定的喷杆使化学药剂更接近于植物,使风力的负面影响大大减少。 拖拉机的振动能够由一个被动或主动的悬浮喷杆来相应的削减。静态悬浮装置由 不需要电源的液压缸、联通器和阻尼组成。被动3,4或主动减振器4-7由一个 或多个驱动器、感应器、信号传感器、滤波器、监察人、钟摆补偿组成,为了减 轻拖拉机上的喷杆不良滚动,这项课题已经被认知。主动方式是用古典频域技 术设计的典型的单输入单输出反馈控制系统。在主动系统中,液压驱动电液阀总 是使用的,因为通常液体动力由拖拉机带动。红外线或超声波检测装置,安装在 喷杆上监测喷嘴和地面的垂直距离。托马斯已经详细描述了这些传感器的特点和 动态特征8。在70年代末和80年代,控制学专家融合了最佳的古典理论和现代技术, 研制出新的控制理论。在这个新理论中,健全的补偿,必须满足某些假设的稳定 性和性能标准,将开发有关“hydro track”喷洒机械,在Delano公司工程车间 组装(图1)。线性二次高斯法与回路转换复原法(LQG/LTR方法)将用来作为控 制系统的设计工具。反馈系统通过一个液压器使喷杆在相反的方向抵消拖拉机轧旋的不良运动,这种距离在喷嘴和大田作物间仍然是可接受的范围。2.喷洒机械的运动方程hydro track喷雾机,由10个机构组成:焊接构架上的驾驶室、一个140L 的油箱,88万千瓦的电机,一个喷杆,正在组建的后面的两个车轮与前轴展开 两个前轮。固定在上框的涤纶液体储罐,拥有最大容量为3000L。臂总长度可相 差21和36米。在应用中,臂的长度等于27米.。四个轮子的直径一样为1.34 米,hydrostatically四个驱动波克兰液压马达等。拖拉机位于轮子上方较高处, 以防止在化学喷雾期间田间作物因机械碰触而损伤。拖拉机驾驶室,袖箱和汽车休息橡胶垫保证拖拉机框架的六个自由度。在前 轴悬架有一个三角结构。球形接头里的一个侧滑自由度被阻断,连接一个顶点的 轴与下垫面的拖拉机帧。其他顶点携带前轮。两个氮加载短跑盆充当弹簧-阻尼 系统,均放置在前轴和拖拉机底盘附近前轮以增加乘坐舒适性。压力阻尼器会自 动适应不断变化的喷洒机重量,以保持拖拉机机箱关于领域内的一个恒定的水 平。喷射臂是装在拖拉机的钢架的后方摆机制必须抑制不良的拖拉机的滚动 (图2)。主动悬架系统是放置在硬性规定上的拖拉机的喷杆和钢框之间的液压缸 来获取的。该机构装置共计31个自由度(d.O.f.):相对于土壤的拖拉机底盘有图2:喷雾机臂悬架和驱动器的背面 6d.o.f;关于底盘:驾驶室、油箱和发动机总计18d.o.f.,喷杆有一个转动自由 度,前轴有一个转动和上下的自由度(d.o.f.),每一个车轮有一个上下的d.o.f.。 上述四个液压驱动车轮受制于一个引进的虚构扭传动刚度与每个轮子的传动阻 尼。轮胎与地面的接触长度决定了轮胎上的低通滤波器品质,这取决于轮胎所要 承受的重量,这些已经被考虑在内。两个位移传感器(红外线或超声波)固定在喷 杆的嘴部用来测量喷嘴和土壤或田间作物之间的垂直距离。各个喷洒机器的零件已经在工厂地板上在机器组装期间被测量了。实测数据 已经输入Lexigraphic,一款三维的CAD-CAM-CAE操作软件系统。机器的10 个机构部件的机械参数(尺寸、重心、质量惯性矩和产品的惰性)已经被汇集到 UNIGRAPHICS里面。其他的型号参数(弹簧刚度、阻尼常数)由实验室测量或提 供货物的厂商直接给出。由于拖拉机的全部质量大大下降,在室外的土地上喷洒 操作,一个充满液体的把罐、一个半满的液体储_及一个空储罐底盘的模型参数 已经计算出。与地面接触的轮胎长度已经适应这三种情形。计算公式分别解释了文章中的关于三个不同容量罐体的一部分线性运动方 程。状态空间的转换,它们所代表系统的70个状态:62个状态来自于矢量二阶 模式和当使用Crowell轮胎模型时的8个代表轮胎动态时纵向和横向状态的。这种 状态,是用来在物理结构设计过程中,并在模拟阶段评价真实模型,取代机电液 补偿的。喷雾机的一个半满罐系统矩阵详载于附录。读者也许为便于标记这个矩阵, 会将拖拉机驾驶室、汽车的油箱的18个d.o.f.移取不予考虑,因为它们是无关的 自由度问题。在这种情况下,代表喷杆的转动的自由度是广义拉格朗日坐标Q7。 设计参数和必要的测量数据,在文档中详细描述了 9。3.动态的液压装置 忽视伺服驱动器和动态反馈系统的破坏。其系统方程应该把喷洒机的状态 方程的。由两个辅助状态与状态的变量和Pb可得到1019 汽缸的油容积Ac已经增加了一倍,这是考虑到油在液压管道中的可压缩性 和泄露情况。4.LQG/LTR方法的总结用LQGL/LTR方法设计的这种补偿器,要求一个具有代表性的空间状态的标称模型。 一台基于LQG的补偿器包括一个卡尔曼过滤器和一个调节器。测量信号通 过估计未知状态的卡尔曼过滤器传送出去。被估计的和直接地测量的状态通过传 动器由调节器产生驱动信号(s)。在无限(旧)时间不变的情况下,双重性原则和分离原则允许我们计算调节增益矩 阵K和卡尔曼增益矩阵K,独立地彼此又相似的规程11,只要等式4是可以 成立和计算求解的。这意味着无法控制和/或不可预见的模式逻辑(4)应渐近趋于 稳定。因为只有测量,此应用可以被视为一种输出反馈系统过滤器(相反的状态 反馈系统的所有状态测量和反馈,而不用直接观察)。由于这个原因,应该在调节 之前设计卡尔曼滤波器的逻辑。全状态反馈LQ控制器的相位幅度至少为60 (纯相位变动的60可能同时被容 忍在各种没有疏松的稳定输入渠道里)增益幅度无限大(增益在每个输入通道可 以增加无限大在不考虑疏松的稳定前提下)15;坏处增益边缘反增益在每个频道 的投入至少可以减少1/2或8分贝16。然而,这些令人印象深刻的稳定性不太 容易保证,尤其在实施最佳观测时。幸的是,存在着已设计的调整程序能充分恢复稳定性差的全状态反馈系统17。5.标称模型在复杂的机制中所描述的大型模型和众多的状态下设计补偿器期间,设计者 常常釆用如下两种模型:一种详细的评估模型或真实的模型代替真实的物理过程 的阶段进行模拟,另外一种是一个较小的设计模型或象征模型通常是从评价模 型,即使用综合补偿器。这个做法是根本的基于模型的补偿器开发的当控制系统 设计技术被运用,为了保持卡尔曼过滤器的维度可接受。LQG/LTR方法属于那 个小组,因为植物的标称模型将被合并在估计缺掉状态的植物在控制活动期间的 卡尔曼过滤器。一个标称模式应该从评估的模式中导出来,以一贯的方式,即设计模型必须尽可 能小,以维护尽可能多的信息。真正的模型,从一个半满罐的hydro track,看起 来似乎是最可行的选择减少的模型中导出。在这项研究中,减少模型可以遵循的 结构输出分布矩阵C(附录),这表明,只有拖拉机的旋转运动和喷杆,代表广义拉格朗日坐标仏和扔,都属于实测输出。因此听起来逻辑保留而必及其衍生物,连同仏和巧,作为状态的设计模型。被减少的标称模型的准确性与六个状 态(附录)由确认它的输入-输出页与原物的输入-输出页评估模型进行比较。图3 显示PG在整个频率范围内,均表现出完美的雷同,唯一的例外是由截短拖拉机 模式所导致的约20 rad 1的小偏差。6.结论一个详细的线性化的模型操作在由典型的Crowell模型代表的喷洒机器,由 multiband方法在第本文的的第一部分的概述中导出。虽然标称模型的6个状态 直接地从大拖拉机模型中推论出来,而不是使用被提炼的平衡的减少技术,但它 依然显示拥有一个充足的精确度。以这些模型,由于LQG/LTR方法的内在质量,喷杆的活跃悬浮成功地被设想了。严格的性能指标都容易得到满足,而不釆用成型滤波器,补偿器保留慢响 应对大型拖拉机大量变动和恢复的稳定边际创造对非模型动摇的有些免疫能输 入系统的动态现象作动器输入。同时,也表明强壮性测试针对非结构化模型的不 确定性是必要的,它们的成功应用是坚决通过提供可靠的评价模型得到的。喷洒应用机械喷雾器的基本单位和心脏是液体泵。因此,首先需要研究和确定液体泵的一 些运行参数。正如所有雾化技术一样,都需要外加的能源进行对液体的解体作用, 以完成雾化。航空股和旋转式雾化在能源供应乘飞机或离心力实现了雾化。水栗 是常用这些技术已获得均匀效果的。但对于液压喷嘴压力的气溶胶液体雾滴由泵 (或压缩天然气)作为能量来源。栗的类型泵机可以分为正面位移和非正面的类型。第一种形式来取代具体的液体体积 (空气)的革命。这意味着一些压力从阀释放,或者压力控制装置使用未被利用 的回水缸进行喷雾操作。容积式泵还将借助低真空,因此,也不会要求充填泵或 将它与下面的液体为首,然后开始抽水。非正面的泵(主要是离心),不需绕道阀, 不需要自己抽空气,但一般有更长的寿命比正面水泵,需要装修接近旋转部件 和受到快速磨损尤其磨料悬浮或湿粒子。A MODELLING PROCEDURE FOR LINEARIZED MOTIONS OF TREE STRUCTURED MULTIBODIES2: DESIGN OF AN ACTIVE SPRAY BOOM SUSPENSION ON A SPRAYING-MACHINEH.Ramon and J. De BaedekerK.U.Juvenilia, Department of Agricultural Engineering, Kardinaal Mercierlaan 92.3001 Leuven, Belgium(Received 26 August 1994) Abstract-In part 1 of the paper, the linearized equations of motion of a multiband system have been established. In this part, the method is used to compute the equations of motion of a spraying-machine consisting of 10 bodies. Ayres are represented by the Tyre model of Arolla. The contact length Tyre-ground which determines the low-pass filtering quality for the Ayres, is also taken into account. Through a smaller nominal model that has been derived directly from the multiband model, an active spray boom suspension is designed with the aid of the linear quadratic Gaussian method with loop transfer recovery. A hydraulic actuator counteracts undesired rolling of the tractor by rotating the spray boom in the opposite direction, such that the distance between the spray nozzles and the field crops remains within an acceptable range. In the simulations, compensated and uncompensated spray boom motions are generated by driving the machine over some incompressible standardized tracks and corresponding spray deposit distributions are generated.NOTATIONAc net area of the cylinder m2Cddimensionless discharge coefficient Gtrue plant modelGOnominal plant modelGa additive unstructured uncertaintiesGm additive unstructured uncertaintiesHOOopen loop transfer matrix of the Kalgan filter and plant evaluated al the output (=loop gain,return ratio)HOSopen loop transfer matrix of the Kalgan filter n*n-identity matrix1.INTRODUCTIONAgricultural production suffers severe losses from insects, plan diseases and weeds. Owing to an exponentially growing world population, crop proProtection has become one of the most important field operations to increase productivity and crop yield.Current methods of plant protection are classified in five categories: chemical, biological, agronomical, mechanical and biophysical techniques 1. Chemical control methods are Stilton most frequently utilized. Their efficiency is large, they are easy to employ and they-have a broad spectrum of applications: herbicides, pesticides, insecticides, which can be delivered by the same machinery. These chemicals are dissolved in a carrier liquid which is distributed over the field crops through tractors equipped with a spray boom.New tendencies towards the use of concentrated spraying agents (small volume spraying techniques), the rising cost of chemicals and increasing concern over pollution pressure on the environment moresque sophisticated spraying-machines which have to be able to spray the liquid as uniformly as possible across the field.Irregularities in the spray pattern are mainly acreacted by pressure variations in the hydraulic equipment, badly set (tuned) spray nozzles, a varying driving speed of the tractor, wind and last, but not least, by unwanted rolling and to a lesser degree by vertical translations of the spray boom. Both boom motions are caused by undesired movements of the tractor body that arc mainly effected by soil roughnesses. As a consequence, the vertical distances between crops and nozzles are changed continuously which results in an irregular spray deposit coistrilablution. Higher work velocities, made possible by the use of more powerful agricultural machines, even magnify vibrations, effected by soil irregularities, on tractor and implement- All these negative effects on Che spray pattern are more thoroughly explained in Ref. 2.Obviously, compensation of unwanted spray boom motions become more than ever an interesting and challenging research area. Besides, stabilized spray booms offer the possibility of dispersing the chemicals closer to the plants so that negative wind, effects are strongly reduced. Attenuation of the boom response to tractor vibrations can be accomplished by passive or active boom suspensions. Passive suspensions are a combination of springs, links and dampers and do not require a power supply. Active suspensions consist of a power source, one or more actuators, sensors, signal transducers, filters and controllers. Pendulum compensators with passive 3,4, or active dampers 4-7, in order to attenuate undesirable rolling movements of a spray boom on a tractor, have already been studied. The active versions are typical examples of single-input single-output feedback conrotl systems which are designed with classical arc- frequency-domain techniques. In an active system, hydraulic actuators with electro-hydraulic valves are always used, because fluid power is normally available on tractors. Ultrasonic or infrared measurement devices, mounted on the boom tips monitor the vertical distances between the tips and the ground. The characteristics and dynamics of these sensors are fully described by Thomas 8.At the end of the 1970s and during the 1980s, control specialists developed a new control theory that blends the best features of classical and modern techniques. In this respect, a robust compensator that Muslim satisfy some postulated robustness and perconformance criteria, will be developed on the spray- archine “Hydro track”,assembled at the engineering workshop of the company Delano (Fig. 1). The linear quadratic Gaussian method with loop transfer recovery (LQG/LTR method) will be used as a control system design tool. The feedback system should counteract undesigned tractor rolling by RotaING the spray boom in the opposite direction through a hydraulic actuator, such that the distance between the spray nozzles and the field crops remains within an acceptable range. 2.EQUATIONS OF MOTION OF THE SRRAVIN&MACHINEThe spraying-machine, Hydro track, consists of 10 bodies: a welded frame on which the cab, a fuel tank of 140 , a motor of 88 kW, a spray boom, two rear wheels and a front axle with two mounted from wheels, are built. A polyester liquid tank, fixed onto the frame* has a maximum content of 30001. The total boom length can vary between 21 and 36 RA. In this application, the length of the boom equals 27 m. The four identical wheels have a diameter of 1.34 m and are hydrostatically driven by four McClain hydraulic motors. The tractor stands high on its wheels to prevent field crops from mechanical damage during the chemical treatment,The tractor cab,the fuel tank and the motor rest on rubber cushions which preserve six degrees of freedom with regard to the tractor frame. The front axle suspension has a triangular structure. A Hesperidcal joint in which the yawing degree of freedom is blocked, connects one vertex of the axle with the underside of the tractor frame. The other invertins carry the front wheels. Two nitrogen-loaded dash pots that serve as spring-damper systems are placed between the from axle and Che tractor chassis near the front wheels to increase ride comfort. The pressure in the dampers is automatically adapted to the changing weight of the spraying-machine in order to retain the tractor chassis on a constant level with regard to the field. The spray boom is mounted on a steel frame at the backside of the tractor with a pendulum machanism which must attenuate undesired rolling of the tractor (Fig. 2). An active suspension system is obtained by placing a hydraulic cylinder between the spray boom and the steel frame that is rigidly fixed onto the tractor. The mechanism has in total 31 degrees of freedom (d.o.f.): 6 d.o.f. of the tractor chassis with regard to the soil; with regard to the chassis: in sum IS d.o.f. for the cab, the fuel tank and the motor, a rolling d.o.f. of the spray boom, a rolling and pitching calo.f, of the front axle and for every wheel 1 pitching d.o.f. The rotational d.o.f. of theLinearized motions for tree structured embodiers. Part 2four hydrostatically driven wheels are restricted by the introduction of a fictitious torsional driveline stiffness and driveline damping for each wheel. The contact length Tyre-ground which determines the outpass filtering quality of Che Ayres and which depends on the weight the Ayres has to bear, is taken into account. Two displacement sensors (infrared or ultrasonic) arc fixed onto the boom tips and register the vertical distance to the soil, or the field crops.Each part of the spraying-machine has been measured on Che factory floor during the assemblage process of the machine. The measured data have been imported in UNIGRAPHICS, a three-dimensional CAE-CAD-CAM system. The mechanical parPetersham of the 10 bodies in the machine (masses Centre of gravity, mass moments of inertia and products of inertia) have been generated within UNIGRAPHICS. The other model parameters (spring stiffness, damping constants) were measured at the laboratory or were disposed by kind permission of the manufacturers* Since the total tractor mass decreases considerably during Che spraying operation in the field, the model parameters of the chassis have been calculated for a full liquid tank, a half-full liquid tank and an empty liquid tank. The contact length Tyre-ground is adapted to these three aituNations.The linearized equations of motion are computed with the formula explained in part one of the paper for the three different tank contents. Transformed into the state-space, they are parented by a system of 70 states: 62 states derived from the vector second-order model and 8 states that represent the longitudinal and lateral Tyre dynamics when using the Tyre model of Arolla. This state equation is used as an evaluation or true model that replaces the physical structure during the design of the ectropic-hydraulic compensator, and in the simulation phase.The system matrices of the spraying-machine with a half-full tank are given in the Appendix. The reader should remark that for the ease of prepdenting the matrices, the 18 d.o.f. of the tractor cab, the motor and the fuel tank are removed because they are irrelevant to the problem. In this situation, the rolling degree of freedom of the spray boom is represented by the generalized Granola运an coordinate q1. The design parameters and the ne cessary measured data are thoroughly described in Ref, 9,3.DYNAMICS OF THE HYDRAULIC DEVICESNeglected overvalue and actuator dynamics can destabilize the feedback system. Their system equations should therefore be incorporated in the state equations of the spraying-machine.Two supplementary states with state variables pa and Pb are obtained 10 In whichThe oil volume in the cylinder has been doubled in order to take into account the compressible oil in the hydraulic conduits and hoses.4.SUMMARY OF THE LQG/LTE METHODThe compensator is designed with the LQG/LTR method that asks for a state space representation of the nominal model An LQG-based compensator consists of a Kalgan filter and a regulator. Measurement signals are sent through a Kalgan. filter which estimates the unknown states. The estimated and direct measured states arc used by the regulator that generates the actuator signal(s).In the infinite horizonIH) time-invariant aituNation, the duality principle and the separation pinSiple permit us to calculate the regulator gain matrix K,. and the Kalgan filter gain matrix Ef Independencedecently of each other with similar procedures 11, as long as ean (4) is stabilization and detectable. This means that the uncontrollable and/or unobservable modes of ean (4) should be asymptotically stable.Since only the output is measured, this application can be considered as an output feedback system with filter (contrary to a state feedback system where all the states are measured and fed back directly without observer). For that reason, it sounds logical to design the Kalgan filter before the regulator.Fig. 4. Inputoutput PG of the evaluation model with full tank (solid line) and empty tank (dashed line).To modify Kc or the PG of H00 by manipulation of the state weighting and control weighting matrices Q and R, equivalence loop shape techniques can be used 13. A full-state feedback LQ-controller has a phase margin of at least 60 (pure phase changes of 60 can be tolerated in each input channel simultaneously without loosing stability) and a gain margin of infinitely (the gain in each input channel can be increased infinitely without loosing stability) 15; the downside gain margin against gain reductions in each input channel is at least 1/2 or 8 dB However, these impressive stability margins arc not guaranteed any more In an optimum observer-based implementation. Fortunately,there exists a design adjustment procedure to recover the stability margins of the full state feedback system 17. 5. NOMINAL MODEJLDuring the design of compensators on complex mechanisms which arc described by large models with numerous states, the designer often employs two types of models: a detailed evaluation model or trueremains within the boundary of 士 L5V, which is only 13% of its total range (Fig. 10),the pressure in chamber a of the actuator fluctuates between 26 bar and 236 bar (Fig. 1 i). This represents more than 70% of the acceptable pressure range which argues for the chosen safety marn of 士 20,000从 How the cultimate target of reducing irregularities in the spray deposit distribution is reached, is shown in Table 3 and Fig. 12. The over application is decreased from 350 to 105% (ideal 100%) and the under Applingcation, which is worst in the middle between the spray nozzles, is increased from 0 to 96%.10. CONCLUSIONSA detailed linearized model of an operational spraying-machine in which the Ayres are represented by the Tyre model of Arolla, has been derived with the multiband method outlined in Pan 1 of the paper. Although the normalize model of 6 states was directly deduced from the large tractor model, instead of using more refined balanced reduction techniques, it is shown to possess a sufficient precision.With these models* an active suspension of a spray boom has been conceived successfully* owing to the intrinsic qualities of the LQG/LTR method. Citringent performance specifications are easily fulfilled without the introduction of shaping fillers, the comdispensator remains insensitive to large tractor mass variations and the recovered stability margins create a certain immunity to modeled destabilizing dynamic phenomena which could enter the system at the actuator input. It is also demonstrated thatmodel which replaces the real physical process Turin the simulation phase and a smaller design model c nominal model that is no- 配套讲稿:
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