數(shù)控系統(tǒng)輔助液壓挖掘機(jī)的概念課程畢業(yè)設(shè)計(jì)外文文獻(xiàn)翻譯@中英文翻譯@外文翻譯

Abstract A concept of digital control system to assist the operators of hydraulic excavators is presented and discussed. Then, control system based on described ideas was mounted on a special numerically controlled stand, equipped with D r A and A r D converters, where small hydraulic backhoe excavator K-111 fixtures were used. Experimental results shows that it fulfils all described requirements and can be used as the machine operator assist. It enables for precision tool guidance. automatic repetition of realized movements, realization of specific tool trajectories including energetically optimal path sand automatic improvement or optimization of realized paths. Tool trajectories can also be prescribed using the setting model, making excavator the machine of tele operator class. Presented system can be used as a basis for real machine control system. q 1998 Elsevier Science B.V. All rights reserved. Keywords: Digital control system; Hydraulic excavators; Tool trajectories 1. Introduction The automation of heavy machines, including hydraulic excavators, began in mid-1970s and was possible due to invention of real time controllers and hydraulic elements with good dynamic properties. The first excavator equipped with several mechatronics systems, which was shown as a working model, was the excavator FUTURE prepared by Orenstein and Koppel for BAUMA83 Fairs. Since that time, machines equipped with systems automating the engine operation, pumps operation, machine fixtures, machine diagnostic, etc., are presented and offered. Such systems bring real help to the operator and clear economical profit. For example, LIEBHERRR902 excavator equipped with LITRONIC System. has for a trench digging the efficiency 40% higher and unit costs 30% lower, than similar machine without such automatic system. Although automation . in some case, optimization of several machine systems develops quite fast, the main machine process the shoving processhas no proper understanding and description until now. Its automation is quite limited to systems repeating already performed. movements, laser levelling systems, etc. and systems optimizing such processes are not developed yet. Quite new experimental results show clear idea for energetically optimal tool trajectories in the case of cohesive materials. The tool tip has to be guided along slip lines, which are generated from the tip tool during the previous stage of the shoving process. To realize such trajectories for practical purpose and real machines, it is necessary to build a special control system for the tool motion, which enables automatic realization of such trajectories as well as realization of other tasks that help the operator. 2. The basic concept of the computer aided control systemIt It was shown before that analyzing the the soil deformation during the shoving process, it is possible to determine energetically optimal cutting tool trajectories. Hence, the automatic tool movement along slip lines generated in cohesive material has to be a quite important option of proposed system. It should also enable precision tool guidance, automatic repetition of already realized movements . for example, teach-in , realization of some tool movements impossible to realize manually, etc. Taking into account to-day experience with automation of heavy machines, such system should be constructed to assist machine operator, who still plays a main decisive and control role. Hence, the proper separation of tasks, between the control sys-tem and the operator, is necessary. Such control system for excavators was built on laboratory scale. Its basic assumptions can be stat d w x . as follows 13 : 1 operation of the central control system is based on cooperation of two digital systems. The first one controls directly the motion of the machine fixture using the control system of the hydraulic cylinders position. The second one works . out control signals for the first one. 2 Under the standard work conditions, action of the proportional hydraulic valves of the fixture cylinders is controlled through the computer. The direct operator control is . possible only in case of emergency conditions. 3The feedback between the machine environment and control system is realized through the operator. He participates continuously in the process of the con- . control of machine fixtures motion. 4 For realization of the tool motions which are impossible for manual control, the operator has a possibility to coordinate displacement of separate cylinders by means of hard- . ware or software. 5 The operator has a possibility to switch into automatic control of the fixture motionto realize a special tool trajectories. For example, it can be energetically optimal tool trajectory where tool tip moves along slip lines or specific trajectory . realized and stored previously. 6 The optimal cut-ting tool trajectories can also be realized as correction of trajectories given by the operator. Such correction is done mainly during the time parametrization of the tool path. 7 The trajectories given by the operator can be corrected by the system to take in toaccount such limitations as geometrical ones, maxi-mal power of the pump, maximal output of the pump, maximal pump efficiency, etc. Presented concept is based on such cooperation between the operator and control system that the fixture movements are controlled by the operator while the control system corrects him or, when ordered, can act automatically 3. Examples of the control system functioning The control system based on described above ideas was mounted on a special numerically con-trolled stand, equipped with PC computer having CrA and ArC converters, where small hydraulicw x backhoe excavator K-111 fixtures were used 1417 .The control system of the fixture motions utilizes the control system of the cylinder positions. The fixture cylinder displacement is controlled by the proportional hydraulic valves fed by the variable out putmultipiston pump. The control system for fixture cylinders is based on three control systems, each to control different cylinder displacement using PID or state control ler w x 14 . It enables control of the fixture motions using different methods of the tool trajectory planning, measuring of acting forces and displacements and determining other magnitudes related to the fixture movements. Experimental data acquisition is also possible. One of quite important problems, which should betaken into account when building the control system, is the way of the tool trajectory planning. It is . w x realized as usually in two steps 15 . In the first one, the trajectory shape is planned and determined. In the second one, the trajectory curve is parametric zed in time in a determined manner, what defines the trajectory within the generalized coordinate space. On this basis, the time runs of the generalized coordinates describing the configuration space of the machine are determined. In the case of an excavator, lengths of hydraulic cylinders are those coordinates 3.1. The tool mo ement along prescribed line The control system build for experimental standw x 1517 enables, among others, programming the work motion in the excavator work space, or in its configuration space, using point to point technique. In this method, the coordinates of the initial and final points, and sufficient number of the character isticnodal points, are defined. Values describing this points are then introduced to the system, where remaining points of the trajectory are calculated using interpolation methods. Linear or the third degree polynomial interpolation is used. The trajectory y parametrization in time can be realized through: determination of the total trajectory run-time and its division into individual segments of the path. System calculates the velocities of cylinders, determination of the run-time between following nodal points, taking into account some limitations . or conditions for optimization .In the case of standard excavator construction, it is quite difficult to precisely realize trajectories, where simultaneous movement of two or three cylinders is necessary. 3.2. The tool mo ement using the setting model along straight lines In presented case, the coordination of the fixture cylinder movement was realized by hardware, that means using the setting model. It can also be realized by software. The machine operator using special. buttons , can generate horizontal or vertical tool movement preserving the constant value of the tool cutting angle in every point of the machine working space. The prescribed tool path is stored using the point method in the configuration space. Further-more, the machine operator determines motion velocity which is corrected by control system taking in to account the feeder output. In Figs. 7 and 8, results of such control for the horizontal tool movement are shown. The cutting tool trajectory is presented in Fig. 7. In Fig. 8, the fixture cylinder lengths calculated for prescribed velocity are drawn with solid line. Their calculated lengths assumes the feed erout put are drawn with dotted line. The way of the tool path time parametrization was similar to that using the setting model. It is seen that velocities given by the operator are too high and system corrected cylinder motion timing to keep assumed feeder output. The example of the tool motion along the inclined line is presented in Figs. 9 and 10, where the tool trajectory and corresponding cylinder lengths are drawn. Such movement is realized as a sum of horizontal and vertical tool motions the line inclination depends on proportions between horizontal and. vertical velocities . For example, the tool trajectory long inclined line can be realized during the . withdraw stage of the shoving process Fig. 2 to follow the slip line or for automated, making the soil scarps. 3.3. Automatic tool mo ement along a slip line Analysis of experimental results of the soil shoving process shows that it is possible to predict theoretically the slip lines positions and energy etically optimal tool trajectories. It can be done for homogeneous material under laboratory conditions. In real situations, when material is not homogeneous and not well-defined, the material sleep lines has to be detected automatically. The procedure of automatic slip line detection is based on the observation that when cutting tool begins to penetrate more dense material, then the in crease of the horizontal force acting on the tool is observed. Such situation takes place also when the tool tip moves from the slip line where material. density is quite small to the virgin material material. not deformed beforebehind the slip line . Hence, the observed increase of the pushing force can be used for slip line detection. Such procedure, which simplified version is described below, can be realized as follows. Cutting tool motion is realized as a sum of horizontal, vertical and rotational movements and horizontal reaction of the soil is measured and followed. Firstly, the tool moves horizontally up to the moment when the horizontal force drops, that coincides with creation of slip lines system originating from the tool . end Fig. 1 . If such slip lines cannot be created as a result of horizontal pushing, a special procedure for. example tool rotation can be applied. Then, tool is moved vertically by prescribed displacement value and then moves again horizontally rotation of the. tool can be added up to the moment when horizontal force begins to increase. If so, , and then horizontally, and so on. This way, the tip of the tool automatically follows in a step way the slip line. Results of such preliminary tests are presented in Figs. 11 and 12. As a simplified model, the possibility of automatic tool movement along the soil scarpinclined with 0.61 rad. was investigated. For defined values of maximum horizontal force and defined vertical displacement, the control system automatically followed the tool along the scarp. The horizontal force vs. horizontal displacement and tool trajectory are shown in Fig. 11. The magnified fragment of Fig. 11, which shows the way in which system is acting, is presented in Fig. 12. 4. Conclusions Experimental results show that presented control system fulfils all described requirements and can be used as the machine operator assist. It enables for precision tool guidance, automatic repetition of realized movements, realization of specific tool trajectories including energetically optimal paths and automatic improvement or optimization of realized paths. Tool trajectories can also be prescribed using the setting model, making excavator the machine of tele operator class. Presented system can be used as abas is for real machine control system. Acknowledgements This research was sponsored by the Project KBN7T07C00412 Optimization of the soil shoving process due to heavy machines of an excavator type realized at Kielce University of Technology. 數(shù)控系統(tǒng)輔助液壓挖掘機(jī)的概念 摘要 數(shù)控系統(tǒng)輔助液壓挖掘機(jī)操作者的概念被提出和討論。然后，基于描述概念性的控制系統(tǒng)被安裝在專門的數(shù)控平臺(tái)上，平臺(tái)上配備 D/A 和 A/D 轉(zhuǎn)換器，已經(jīng)在小型液壓拉鏟挖掘機(jī) K-111 的工裝上應(yīng)用。實(shí)驗(yàn)結(jié)果表明它能滿足所有描述的需求，并且能用于輔助 機(jī)器操作員工作。它能為精密工具做引導(dǎo)，了解的運(yùn)動(dòng)的自動(dòng)重復(fù)和特定工具軌道 (包括最佳的路徑 )，還有自動(dòng)改進(jìn)或優(yōu)化路徑。工具軌道也能被規(guī)定使用設(shè)定模型，使挖掘機(jī)成為遙控操縱類別的機(jī)器?，F(xiàn)行的系統(tǒng)能基本用于真機(jī)控制系統(tǒng)。 1998 Elsevier 科學(xué) B.V. 版權(quán)所有。 關(guān)鍵詞 ： 數(shù)控系統(tǒng)；液壓挖掘機(jī)；工具軌道 1 介紹 重型機(jī)械的自動(dòng)化，包括液壓挖掘機(jī)在內(nèi)，始于 20 世紀(jì)七十年代中期并成為可能。這主要由于時(shí)實(shí)控制系統(tǒng)和高動(dòng)力性能的液壓元件的發(fā)明。第一臺(tái)配備若干機(jī)械電子系統(tǒng)的挖掘機(jī)被當(dāng)作模型展示，這是 Orenstein 和 Koppel 為 BAUMA83 展覽會(huì)準(zhǔn)備的未來(lái)的液壓挖掘機(jī)。自從那次以后，許多配備了自動(dòng)控制系統(tǒng)的器被展現(xiàn)和要求 如引擎操作，泵操作，機(jī)器工裝，機(jī)器診斷等等。這種系統(tǒng)帶來(lái)了真正的幫助和明顯的利潤(rùn)。舉例來(lái)說(shuō) , 被裝備 LITRONIC 系統(tǒng)的 LIEBHERR R902 挖掘機(jī)（對(duì)于挖溝機(jī)），對(duì)比沒(méi)有配備這種自動(dòng)控制系統(tǒng)的相同機(jī)型來(lái)說(shuō)，效率提高達(dá) 40成本降低 30。雖然一些機(jī)器的自動(dòng)系統(tǒng)（在一些情況下的優(yōu)化）發(fā)展的相當(dāng)快，但是直到現(xiàn)在主要的機(jī)器程序推處理 -沒(méi)有適當(dāng)?shù)睦斫夂兔枋?。它的自?dòng)化相當(dāng)?shù)挠邢蓿ㄈ缰貜?fù)運(yùn)動(dòng)和激光平行系統(tǒng)等等），并且優(yōu)化處理系統(tǒng)還沒(méi)有發(fā)展。比較新的實(shí)驗(yàn)結(jié)果清晰地表明，優(yōu)化的工裝軌跡在連續(xù)材料情況下，工具的尖端不得不沿著前一個(gè)推擠過(guò)程形成的滑道運(yùn)動(dòng)。實(shí)際上了解這樣的軌跡和真機(jī)，為工具的運(yùn)動(dòng)建立了一個(gè)特別的控制系統(tǒng)是必要的，這使得實(shí)現(xiàn)這樣的軌跡像實(shí)現(xiàn)其它幫助操作員實(shí)現(xiàn)其它任務(wù)一樣?？紤]到日益加重的機(jī)器的發(fā)展，這種系統(tǒng)必須適應(yīng)數(shù)控電 液驅(qū)動(dòng)。經(jīng)核實(shí)試驗(yàn)結(jié)果，這種控制系統(tǒng)的概念在這篇文章中提出。 2 計(jì)算機(jī)輔助控制系統(tǒng)的基本 據(jù)之前顯示，在推土過(guò)程中分析土體變形的力學(xué)機(jī)理，可能決定刀具軌跡的優(yōu)化。然而，在連續(xù)的材料中產(chǎn)生了工具沿著滑線的自動(dòng)移動(dòng)，這必須成為被提倡的系統(tǒng)的一個(gè)重要選項(xiàng)。這也應(yīng)該成為精密工具的向?qū)?，自?dòng)重復(fù)已經(jīng)確認(rèn)的運(yùn)動(dòng)（例如“討論會(huì)”），實(shí)現(xiàn)一些手工不能實(shí)現(xiàn)的工具動(dòng)作等等。 考慮到對(duì)重型機(jī)器自動(dòng)化的經(jīng)驗(yàn)少，這樣的系統(tǒng)應(yīng)該被裝配在機(jī)器 上來(lái)協(xié)助操作員，并且扮演決定性和控制性的角色。因此，在控制系統(tǒng)和操作員之間的適當(dāng)?shù)姆蛛x是必要的。 這種用于挖掘機(jī)上的控制系統(tǒng)是建立在實(shí)驗(yàn)室范圍上的，其基本假設(shè)可以闡述如下 13，（ 1）控制中心的操作系統(tǒng)是基于兩個(gè)數(shù)字系統(tǒng)的協(xié)作下的。第一個(gè)通過(guò)控制液壓缸的位置來(lái)控制機(jī)械夾具的運(yùn)動(dòng)。第二個(gè)為第一個(gè)系統(tǒng)產(chǎn)生控制信號(hào)。（ 2）在標(biāo)準(zhǔn)工況下，夾具液壓缸的比例液壓閥通過(guò)計(jì)算機(jī)來(lái)控制。直接的操作員控制僅在出現(xiàn)緊急情況下才能用。（ 3）機(jī)器環(huán)境和控制系統(tǒng)之間的反饋是通過(guò)操作員來(lái)實(shí)現(xiàn)的。他連續(xù)的參加機(jī)器夾具運(yùn)動(dòng)控制的過(guò)程中。（ 4）為了了解這種人工控制不能實(shí)現(xiàn)的工具運(yùn)動(dòng)，操作員有可能通過(guò)硬件或軟件來(lái)調(diào)整單個(gè)液壓缸的位移。（ 5）操作員有可能轉(zhuǎn)換夾具運(yùn)動(dòng)的自動(dòng)控制來(lái)認(rèn)識(shí)特殊的工具軌跡。在這里，工具的尖端沿著滑線或特定的已經(jīng)確認(rèn)的或是事先存在的軌跡移動(dòng)。（ 6）優(yōu)化的工具軌跡也可以被認(rèn)為是操作員給定的軌跡的修正。（ 7）系統(tǒng)可以在考慮某些限制的基礎(chǔ)上來(lái)修正操作員說(shuō)給定的軌跡，如：幾何關(guān)系限制，泵的最大能力限制，泵的最大輸出限制和泵的最大功率限制等等。 現(xiàn)行的概念是基于操作員和控制系統(tǒng)之間的協(xié)作，這就是說(shuō)夾具的移動(dòng)是在控制系統(tǒng)修正下的操作員的 控制或是在操作員的命下控制系統(tǒng)的自動(dòng)化控制。 3 控制系統(tǒng)功能實(shí)例 控制系統(tǒng)基于上述理念被安裝在一個(gè)特殊的數(shù)控場(chǎng)合，配備有 PC 和 C/A、A/C 轉(zhuǎn)換器。在小型液壓挖掘機(jī) K-111 的設(shè)備中有所應(yīng)用 14-17。夾具利用液壓缸的位置控制系統(tǒng)來(lái)實(shí)現(xiàn)夾具的位移控制。夾具液壓缸位移是靠變量柱塞泵反饋的成比例液壓值來(lái)控制的。夾具液壓缸控制系統(tǒng)基于三個(gè)液壓控制系統(tǒng)，每個(gè)控制系統(tǒng)應(yīng)用 PID 或是狀態(tài)控制器，控制不同的液壓缸的位移 14。 它可以用 工具軌跡計(jì)劃編制，測(cè)量作用力和位移，以及其它于夾具位移有關(guān)的量來(lái)控制夾具的 位移。實(shí)驗(yàn)的數(shù)據(jù)的獲得也是可行的。 當(dāng)建立控制系統(tǒng)時(shí)，應(yīng)該考慮的相當(dāng)重要的問(wèn)題之一是工具軌跡計(jì)劃編制的方法。這種方法（通常）從兩步來(lái)認(rèn)識(shí)