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附錄A譯文.
機(jī)器人和機(jī)械手
作者:Makoto Jinno, Tokyo(JP); Takamitsu Sunaoshi, Yamato-Shi(JP); Shiro Tsukada, Yokohama-shi(JP)
機(jī)器人是典型的機(jī)電一體化裝置,它綜合運(yùn)用了機(jī)械與精密機(jī)械、微電子與計(jì)算機(jī)、自動(dòng)控制與驅(qū)動(dòng)、傳感器與信息處理以及人工智能等多學(xué)科的最新研究成果,隨著經(jīng)濟(jì)的發(fā)展和各行各業(yè)對自動(dòng)化程度要求的提高,機(jī)器人技術(shù)得到了迅速發(fā)展,出現(xiàn)了各種各樣的機(jī)器人產(chǎn)品?,F(xiàn)代工業(yè)機(jī)器人是人類真正的奇跡工程。一個(gè)像人那么大的機(jī)器人可以輕松地抬起超過一百磅并可以在誤差+-0.006英寸誤差范圍內(nèi)重復(fù)的移動(dòng)。更重要的是這些機(jī)器人可以每天24小時(shí)永不停止地工作。在許多應(yīng)用中(特別是在自動(dòng)工業(yè)中)他們是通過編程控制的,但是他們一旦編程一次,他們可以重復(fù)地做同一工作許多年。機(jī)器人產(chǎn)品的實(shí)用化,既解決了許多單靠人力難以解決的實(shí)際問題,又促進(jìn)了工業(yè)自動(dòng)化的進(jìn)程。
目前,由于機(jī)器人的研制和開發(fā)涉及多方面的技術(shù),系統(tǒng)結(jié)構(gòu)復(fù)雜,開發(fā)和研制的成本普遍較高,在某種程度上限制了該項(xiàng)技術(shù)的廣泛應(yīng)用,因此,研制經(jīng)濟(jì)型、實(shí)用化、高可靠性機(jī)器人系統(tǒng)具有廣泛的社會(huì)現(xiàn)實(shí)意義和經(jīng)濟(jì)價(jià)值。 由于我國經(jīng)濟(jì)建設(shè)和城市化的快速發(fā)展,城市污水排放量增長很快,污水處理己經(jīng)擺在了人們的議事日程上來。隨著科學(xué)技術(shù)的發(fā)展和人類知識(shí)水平的提高,人們越來越認(rèn)識(shí)到污水處理的重要性和迫切性,科學(xué)家和研究人員發(fā)現(xiàn)塑料制品在水中是用于污水處理的很有效的污泥菌群的附著體。塑料制品的大量需求,使得塑料制品生產(chǎn)的自動(dòng)化和高效率要求成為經(jīng)濟(jì)發(fā)展的必然。 本文結(jié)合塑料一次擠出成型機(jī)和塑料抓取機(jī)械手的研制過程中出現(xiàn)的問題,綜述近兒年機(jī)器人技術(shù)研究和發(fā)展的狀況,在充分發(fā)揮機(jī)、電、軟、硬件各自特點(diǎn)和優(yōu)勢互補(bǔ)的基礎(chǔ)上,對物料抓取機(jī)械手整體機(jī)械結(jié)構(gòu)、傳動(dòng)系統(tǒng)、驅(qū)動(dòng)裝置和控制系統(tǒng)進(jìn)行了分析和設(shè)計(jì),提出了一套經(jīng)濟(jì)型設(shè)計(jì)方案。采用直角坐標(biāo)和關(guān)節(jié)坐標(biāo)相結(jié)合的框架式機(jī)械結(jié)構(gòu)形式,這種方式能夠提高系統(tǒng)的穩(wěn)定性和操作靈活性。傳動(dòng)裝置的作用是將驅(qū)動(dòng)元件的動(dòng)力傳遞給機(jī)器人機(jī)械手相應(yīng)的執(zhí)行機(jī)構(gòu),以實(shí)現(xiàn)各種必要的運(yùn)動(dòng),傳動(dòng)方式上采用結(jié)構(gòu)緊湊、傳動(dòng)比大的蝸輪蝸桿傳動(dòng)和將旋轉(zhuǎn)運(yùn)動(dòng)轉(zhuǎn)換為直線運(yùn)動(dòng)的螺旋傳動(dòng)。機(jī)械手驅(qū)動(dòng)系統(tǒng)的設(shè)計(jì)往往受到作業(yè)環(huán)境條件的限制,同時(shí)也要考慮價(jià)格因素的影響以及能夠達(dá)到的技術(shù)水平。由于步進(jìn)電機(jī)能夠直接接收數(shù)字量,響應(yīng)速度快而且工作可靠并無累積誤差,常用作數(shù)字控制系統(tǒng)驅(qū)動(dòng)機(jī)構(gòu)的動(dòng)力元件,因此,在驅(qū)動(dòng)裝置中采用由步進(jìn)電機(jī)構(gòu)成的開環(huán)控制方式,這種方式既能滿足控制精度的要求,又能達(dá)到經(jīng)濟(jì)性、實(shí)用化目的,在此基礎(chǔ)上,對步進(jìn)電機(jī)的功率計(jì)一算及選型問題經(jīng)行了分析。 在完成機(jī)械結(jié)構(gòu)和驅(qū)動(dòng)系統(tǒng)設(shè)計(jì)的基礎(chǔ)上,對物料抓取機(jī)械手運(yùn)動(dòng)學(xué)和動(dòng)力學(xué)進(jìn)行了分析。運(yùn)動(dòng)學(xué)分析是路徑規(guī)劃和軌跡控制的基礎(chǔ),對操作臂進(jìn)行了運(yùn)動(dòng)學(xué)正、逆問題的分析可以完成操作空間位置和速度向驅(qū)動(dòng)空間的映射,采用齊次坐標(biāo)變換法得到了操作臂末端位置和姿態(tài)隨關(guān)節(jié)夾角之間的變換關(guān)系,采用幾何法分析了操作臂的逆向運(yùn)動(dòng)學(xué)方程求解問題,對控制系統(tǒng)設(shè)計(jì)提供了理論依據(jù)。機(jī)器人動(dòng)力學(xué)是研究物體的運(yùn)動(dòng)和作用力之間的關(guān)系的科學(xué),研究的目的是為了滿足是實(shí)時(shí)性控制的需要,本文采用牛頓-歐拉方法對物料抓取機(jī)械手動(dòng)力學(xué)進(jìn)行了分析,計(jì)算出了關(guān)節(jié)力和關(guān)節(jié)力矩,為步進(jìn)電機(jī)的選型和動(dòng)力學(xué)分析與結(jié)構(gòu)優(yōu)化提供理論依據(jù)。 控制部分是整個(gè)物料抓取機(jī)械手系統(tǒng)設(shè)計(jì)關(guān)鍵和核心,它在結(jié)構(gòu)和功能上的劃分和實(shí)現(xiàn)直接關(guān)系到機(jī)器人系統(tǒng)的可靠性、實(shí)用性,也影響和制約機(jī)械手系統(tǒng)的研制成本和開發(fā)周期。在控制主機(jī)的選用上,采用結(jié)構(gòu)緊湊、擴(kuò)展功能強(qiáng)和可靠性高的PC工業(yè)控制計(jì)算機(jī)作為主機(jī),配以PCL-839卡主要承擔(dān)系統(tǒng)功能初始化、數(shù)據(jù)運(yùn)算與處理、步進(jìn)電機(jī)驅(qū)動(dòng)以及故障診斷等功能;同時(shí)對PCL-839卡的結(jié)構(gòu)特點(diǎn)、功能原理和其高定位功能等給與了分析。硬件是整個(gè)控制系統(tǒng)以及極限位置功能賴以存在的物質(zhì)基礎(chǔ),軟件則是計(jì)算機(jī)控制系統(tǒng)的神經(jīng)中樞,軟件設(shè)計(jì)的目的是以最優(yōu)的方式將各部分功能有機(jī)的結(jié)合起來,使系統(tǒng)具有較高的運(yùn)行效率和較強(qiáng)的可靠性。在物料抓取機(jī)械手軟件的設(shè)計(jì)上,采用的是模塊化結(jié)構(gòu),分為系統(tǒng)初始化模塊、數(shù)據(jù)處理模塊和故障狀態(tài)檢測與處理等幾部分。主控計(jì)算機(jī)和各控制單元之間全部由PCL-839卡聯(lián)系,并且由該卡實(shí)現(xiàn)抗干擾等問題,減少外部信號(hào)對系統(tǒng)的影響。 步進(jìn)電機(jī)的啟停頻率遠(yuǎn)遠(yuǎn)小于其最高運(yùn)行頻率,為了提高工作效率,需要步進(jìn)電機(jī)高速運(yùn)行并快速啟停時(shí),必須考慮它的升,降速控制問題。電機(jī)的升降速控制可以歸結(jié)為以某種合理的力一式控制發(fā)送到步進(jìn)電機(jī)驅(qū)動(dòng)器的脈沖頻率,這可由硬件實(shí)現(xiàn),也可由軟件方法來實(shí)現(xiàn)。本文提出了一種算法簡單、易于實(shí)現(xiàn)、理論意義明確的步進(jìn)電機(jī)變速控制策略:定時(shí)器常量修改變速控制方案。該方法能使步進(jìn)電機(jī)加速度與其力矩——頻率曲線較好地?cái)M合,從而提高變速效率。而且它的計(jì)算量比線性加速度變速和基于指數(shù)規(guī)律加速度的變速控制小得多。通過實(shí)驗(yàn)證明了該方法的有效性。 最后,對機(jī)械手主要研究內(nèi)容和取得的技術(shù)成果進(jìn)行了總結(jié),提出了存在的問題和不足,同時(shí)對機(jī)器人技術(shù)的發(fā)展和應(yīng)用進(jìn)行了展望。
研究機(jī)械手控制的目的是保持以計(jì)算機(jī)為基礎(chǔ)的機(jī)械手的動(dòng)態(tài)響應(yīng),以便與一些預(yù)先設(shè)定的系統(tǒng)性能和理想目標(biāo)保持一致。一般情況下,機(jī)械手的動(dòng)態(tài)性能直接依賴于控制算法的效率和機(jī)械手的動(dòng)態(tài)模型??刂茊栴}包括獲得自然的機(jī)械手系統(tǒng)的動(dòng)態(tài)模型,然后指定相應(yīng)的控制規(guī)則或步驟以達(dá)到想要的系統(tǒng)響應(yīng)和性能。
目前的工業(yè)機(jī)械臂控制將每一個(gè)機(jī)械臂的聯(lián)合看做一個(gè)簡單的聯(lián)合伺服。伺服方法不能充分地模仿不同的動(dòng)力學(xué)機(jī)械手,因?yàn)樗雎粤藱C(jī)械手整體的運(yùn)動(dòng)和配置。這些控制系統(tǒng)的參數(shù)的變化有時(shí)是足夠重要,以至于使常規(guī)的反饋控制方法失效。其結(jié)果是減少了伺服響應(yīng)的速度和阻尼,限制了精度和最終效應(yīng)的速度,使系統(tǒng)僅適用于有限精度的工作。機(jī)械手以這種方式控制速度降低而沒有不必要的震動(dòng)。任何在這一領(lǐng)域和其它領(lǐng)域的機(jī)械臂性能增益要求更有效率的動(dòng)態(tài)模型、精密的控制方法、專門的計(jì)算機(jī)架構(gòu)和并行處理技術(shù)。
在工業(yè)生產(chǎn)和其他領(lǐng)域內(nèi),由于工作的需要,人們經(jīng)常受到高溫、腐蝕及有毒氣體等因素的危害,增加了工人的勞動(dòng)強(qiáng)度,甚至于危及生命。自從機(jī)械手問世以來,相應(yīng)的各種難題迎刃而解。機(jī)械手可在空間抓、放、搬運(yùn)物體,動(dòng)作靈活多樣,適用于可變換生產(chǎn)品種的中、小批量自動(dòng)化生產(chǎn),廣泛應(yīng)用于柔性自動(dòng)線。機(jī)械手一般由耐高溫,抗腐蝕的材料制成,以適應(yīng)現(xiàn)場惡劣的環(huán)境,大大降低了工人的勞動(dòng)強(qiáng)度,提高了工作效率。機(jī)械手是工業(yè)機(jī)器人的重要組成部分,在很多情況下它就可以稱為工業(yè)機(jī)器人。工業(yè)機(jī)器人是集機(jī)械、電子、控制、計(jì)算機(jī)、傳感器、人工智能等多學(xué)科先進(jìn)技術(shù)于一體的現(xiàn)代制造業(yè)重要的自動(dòng)化裝備。廣泛采用工業(yè)機(jī)器人,不僅可以提高產(chǎn)品的質(zhì)量與產(chǎn)量,而且對保障人身安全,改善勞動(dòng)環(huán)境,減輕勞動(dòng)強(qiáng)度,提高勞動(dòng)生產(chǎn)率,節(jié)約原材料消耗以及降低生產(chǎn)成本,有著十分重要的意義。
一般機(jī)械手所用機(jī)械部件有滾珠絲杠、滑軌、氣控機(jī)械抓手等。電氣方面有可編程控制器(PLC)、編程器、步進(jìn)電機(jī)、步進(jìn)電機(jī)驅(qū)動(dòng)器、直流電機(jī)、光電傳感器、開關(guān)電源、電磁閥、旋轉(zhuǎn)碼盤、操作臺(tái)等部件??删幊炭刂破靼l(fā)出兩路脈沖到步進(jìn)電機(jī)驅(qū)動(dòng)器,分別驅(qū)動(dòng)橫軸、豎軸的步進(jìn)電機(jī)運(yùn)轉(zhuǎn);直流電機(jī)拖動(dòng)底座和手爪的旋轉(zhuǎn);接近開關(guān)、微動(dòng)開關(guān)、旋轉(zhuǎn)碼盤將位置信號(hào)反饋給主機(jī),由主機(jī)發(fā)出指令來實(shí)現(xiàn)對手臂的伸縮、上下、轉(zhuǎn)動(dòng)位置的控制;主機(jī)發(fā)信號(hào)到氣動(dòng)電磁閥,以控制手爪的張合來抓放物體。針對個(gè)別設(shè)計(jì)可根據(jù)工件的變化及運(yùn)動(dòng)流程的要求隨時(shí)更改相關(guān)參數(shù),具有很大的靈活性和可操作性。
附錄B 原文
Robot and manipulator
Inventors: Makoto Jinno, Tokyo(JP); Takamitsu Sunaoshi, Yamato-Shi(JP); Shiro Tsukada, Yokohama-shi(JP)
Robot is a type of mechantronics equipment which synthesizes the last research achievement of engine and precision engine, micro-electronics and computer, automation control and drive, sensor and message dispose and artificial intelligence and so on. With the development of economic and the demand for automation control, robot technology is developed quickly and all types of the robots products are come into being. The practicality use of robot products not only solves the problems which are difficult to operate for human being, but also advances the industrial automation program. Modern industrial robots are true marvels of engineering. A robot the size of a person can easily carry a load over one hundred pounds and move it very quickly with a repeatability of +/-0.006 inches. Furthermore these robots can do that 24 hours a day for years on end with no failures whatsoever. Though they are reprogrammable, in many applications (particularly those in the auto industry) they are programmed once and then repeat that exact same task for years.
At present, the research and development of robot involves several kinds of technology and the robot system configuration is so complex that the cost at large is high which to a certain extent limit the robot abroad use. To development economic practicality and high reliability robot system will be value to robot social application and economy development. With the rapid progress with the control economy and expanding of the modern cities, the let of sewage is increasing quickly: With the development of modern technology and the enhancement of consciousness about environment reserve, more and more people realized the importance and urgent of sewage disposal. Active bacteria method is an effective technique for sewage disposal,The lacunaris plastic is an effective basement for active bacteria adhesion for sewage disposal. The abundance requirement for lacunaris plastic makes it is a consequent for the plastic producing with automation and high productivity. Therefore, it is very necessary to design a manipulator that can automatically fulfill the plastic holding. With the analysis of the problems in the design of the plastic holding manipulator and synthesizing the robot research and development condition in recent years, a economic scheme is concluded on the basis of the analysis of mechanical configuration, transform system, drive device and control system and guided by the idea of the characteristic and complex of mechanical configuration, electronic, software and hardware. In this article, the mechanical configuration combines the character of direction coordinate and the arthrosis coordinate which can improve the stability and operation flexibility of the system. The main function of the transmission mechanism is to transmit power to implement department and complete the necessary movement. In this transmission structure, the screw transmission mechanism transmits the rotary motion into linear motion. Worm gear can give vary transmission ratio. Both of the transmission mechanisms have a characteristic of compact structure. The design of drive system often is limited by the environment condition and the factor of cost and technical lever. ''''The step motor can receive digital signal directly and has the ability to response outer environment immediately and has no accumulation error, which often is used in driving system. In this driving system, open-loop control system is composed of stepping motor, which can satisfy the demand not only for control precision but also for the target of economic and practicality. On this basis,the analysis of stepping motor in power calculating and style selecting is also given. The analysis of kinematics and dynamics for object holding manipulator is given in completing the design of mechanical structure and drive system. Kinematics analysis is the basis of path programming and track control. The positive and reverse analysis of manipulator gives the relationship between manipulator space and drive space in position and speed. The relationship between manipulator’s tip position and arthrosis angles is concluded by coordinate transform method. The geometry method is used in solving inverse kinematics problem and the result will provide theory evidence for control system. The f0unction of dynamics is to get the relationship between the movement and force and the target is to satisfy the demand of real time control. in this chamfer, Newton-Euripides method is used in analysis dynamic problem of the cleaning robot and the arthrosis force and torque are given which provide the foundation for step motor selecting and structure dynamic optimal ting. Control system is the key and core part of the object holding manipulator system design which will direct effect the reliability and practicality of the robot system in the division of configuration and control function and also will effect or limit the development cost and cycle. With the demand of the PCL-839 card, the PC computer which has a. tight structure and is easy to be extended is used as the principal computer cell and takes the function of system initialization, data operation and dispose, step motor drive and error diagnose and so on. A t the same time, the configuration structure features, task principles and the position function with high precision of the control card PCL-839 are analyzed. Hardware is the matter foundation of the control. System and the software is the spirit of the control system. The target of the software is to combine all the parts in optimizing style and to improve the efficiency and reliability of the control system. The software design of the object holding manipulator control system is divided into several blocks such as system initialization block, data process block and error station detect and dispose model and so on. PCL-839 card can solve the communication between the main computer and the control cells and take the measure of reducing the influence of the outer signal to the control system. The start and stop frequency of the step motor is far lower than the maximum running frequency. In order to improve the efficiency of the step motor, the increase and decrease of the speed is must considered when the step motor running in high speed and start or stop with great acceleration. The increase and decrease of the motor’s speed can be controlled by the pulse freque ncy sent to the step motor drive with a rational method. This can be implemented either by hardware or by software. A step motor shift control method is proposed, which is simple to calculate, easy to realize and the theory means is straightforward. The motor'''' s acceleration can fit the torque-frequency curve properly with this method. And the amount of calculation load is less than the linear acceleration shift control method and the method which is based on the exponential rule to change speed. The method is tested by experiment. A t last, the research content and the achievement are sum up and the problems and shortages in main the content are also listed. The development and application of robot in the future is expected.
The purpose of manipulator control is to maintain the dynamic response of a computer-based manipulator in accordance with some prespecified system performance and desired goals. In general, the dynamic performance of a manipulator directly depends on the efficiency of the control algorithms and the dynamic model of the manipulator. The control problem consists of obtaining dynamic models of the physical robot arm system and then specifying corresponding control laws or strategies to achieve the desired system response and performance.
Current industrial approaches to robot arm control treat each joint of the robot arm as a simple joint servomechanism. The servomechanism approach models the varying dynamics of a manipulator inadequately because it neglects the motion and configuration of the whole arm mechanism. These changes in the parameters of the controlled system sometimes are significant enough to render conventional feedback control strategies ineffective. The result is reduced servo response speed and damping, limiting the precision and speed of the end-effector and making it appropriate only for limited-precision tasks. Manipulators controlled in this manner move at slow speeds with unnecessary vibrations. Any significant performance gain in this and other areas of robot arm control require the consideration of more efficient dynamic models, sophisticated control approaches, and the use of dedicated computer architectures and parallel processing techniques.
In the industrial production and other fields, people often endangered by such factors as high temperature, corrode, poisonous gas and so forth at work, which have increased labor intensity and even jeopardized the life sometimes. The corresponding problems are solved since the robot arm comes out. The robot arms can catch, put and carry objects, and its movements are flexible and diversified. It applies to medium and small-scale automated production in which production varieties can be switched. And it is widely used on soft automatic line. The robot arms are generally made by withstand high temperatures, resist corrosion of materials to adapt to the harsh environment. So they reduced the labor intensity of the workers significantly and raised work efficiency. The robot arm is an important component of industrial robots, and it can be called industrial robots on many occasions. Industrial robot is set machinery, electronics, control, computers, sensors, artificial intelligence and other advanced technologies in the integration of multidisciplinary important modern manufacturing equipment. Widely using industrial robots, not only can improve product quality and production, but also is of great significance for physical security protection, improvement of the environment for labor, reducing labor intensity, improvement of labor productivity, raw material consumption savings and lowering production costs.
There are such mechanical components as ball footbridge, slides, an air control mechanical hand and so on in the design. A programmable controller, a programming device, stepping motors, stepping motors drives, direct current motors, sensor, switch power supply, an electromagnetism valve and control desk are used in electrical connection. The programmable controller output two lines pulses to stepping motors drives to drive the two stepping motors drives on beam and vertical axis; direct current motors drive the rotation of the base and the hand; sensors send signals of location to the mainframe, and the mainframe sends directive to control the extension and contraction, up and down, moves location; the mainframe send signals to control the opening and closing of the hand to carry objects. Related parameters can be changed according to request of the changes of the objects and movement flow at any time change the relevant parameters in the design, so it has great flexibility and operability.
8
實(shí) 習(xí) 總 結(jié)
專 業(yè):
性 質(zhì):
學(xué) 年:
班 級(jí):
姓 名:
學(xué) 號(hào):
指導(dǎo)教師姓名:
實(shí)習(xí)起止日期:
機(jī)械工程學(xué)院
實(shí)習(xí)時(shí)間:3月1日至3月19日
實(shí)習(xí)地點(diǎn):黑龍江科技學(xué)院校內(nèi)
這三周的畢業(yè)實(shí)習(xí)讓我了解了機(jī)械手方面的很多內(nèi)容。機(jī)械手現(xiàn)在在很多場合都很容易見到。我主要學(xué)習(xí)的事工業(yè)機(jī)械手。機(jī)械手是工業(yè)自動(dòng)控制領(lǐng)域中經(jīng)常遇到的一種控制對象。機(jī)械手可以完成很多工作,如搬物,裝配,切割,噴然等等,應(yīng)用十分廣泛。
在現(xiàn)代工業(yè)中,生產(chǎn)過程中的自動(dòng)化已成為突出的主題。各行各業(yè)的自動(dòng)化水平越來越高,現(xiàn)代化加工車間,常配有機(jī)械手,以提高生產(chǎn)效率,完成工人難以完成的或者危險(xiǎn)的工作,可在機(jī)械工業(yè)中,加工,裝配等生產(chǎn)很大程度上不是連續(xù)的。據(jù)資料介紹,美國生產(chǎn)的全部工業(yè)零件中,有75%是小批量生產(chǎn);金屬加工生產(chǎn)批量重有四分之三在50件以下,零件真正在機(jī)床上加工的時(shí)間僅占零件生產(chǎn)時(shí)間的5%,從這里可以看出,裝卸,搬運(yùn)等工序機(jī)械化的迫切性,工業(yè)機(jī)械手就是為實(shí)現(xiàn)這些工序的自動(dòng)化而產(chǎn)生的。目前在我國機(jī)械手常用于完成的工作有:注塑工業(yè)中從磨具中快速抓取制品并將制品傳送到下一個(gè)生產(chǎn)工序;機(jī)械手加工行業(yè)中用于取料,送料;澆鑄行業(yè)中用于提取高溫溶液等等。
專用機(jī)械手經(jīng)過幾十年的發(fā)展,如今已進(jìn)入了以通用機(jī)械手為標(biāo)志的時(shí)代。通用機(jī)械手可以應(yīng)用于更加多的場合,從而節(jié)約了不少的開發(fā)以及設(shè)計(jì)的成本。由于通用機(jī)械手的發(fā)展,進(jìn)而促進(jìn)了智能機(jī)器人的研制。通用機(jī)械手涉及的內(nèi)容,不僅包括一般的機(jī)械、液壓、氣動(dòng)等基礎(chǔ)知識(shí),而且還應(yīng)用了一些電子技術(shù)、電視技術(shù)、通訊技術(shù)、計(jì)算技術(shù)、無線電控制、仿生學(xué)等,因此它是一項(xiàng)綜合性較強(qiáng)的技術(shù)。目前國內(nèi)外對發(fā)展這一技術(shù)都很重視。幾十年來,這項(xiàng)技術(shù)的研究和發(fā)展一直比較活躍,設(shè)計(jì)在不斷的修改,品種在不斷的增加,應(yīng)用領(lǐng)域在不斷的擴(kuò)大。雖然在這方面相對于發(fā)達(dá)國家還有點(diǎn)落后,但是國內(nèi)現(xiàn)在也越來越感覺到機(jī)械手的重要性,國家大力支持相關(guān)的設(shè)計(jì)及產(chǎn)品的開發(fā)。在機(jī)器人的發(fā)展以及機(jī)械手的設(shè)計(jì)上也取得了一定的成果,國內(nèi)每年都將舉行機(jī)器人大賽,以增加研發(fā)單位的交流與合作。
目前國內(nèi)外的發(fā)展趨勢是:
(1)研制有更多自由度的液壓機(jī)械手,這樣機(jī)械手就可以變得更加的靈活,從而完成更加多的動(dòng)作。
(2)研制帶有行走機(jī)構(gòu)的機(jī)械手,這種機(jī)械手可以從一個(gè)工作地點(diǎn)移動(dòng)到另一個(gè)工作地點(diǎn)。
(3)研制維修維護(hù)方便的通用機(jī)械手。
(4)研制能自動(dòng)編制和自動(dòng)改變程序的通用機(jī)械手。
(5)研制具有一定感觸和一定智力的智能機(jī)械手。這種機(jī)械手具有各種傳感裝置,并配有計(jì)算機(jī)。根據(jù)仿生學(xué)的理論,用計(jì)算機(jī)充當(dāng)其大腦,使它進(jìn)行思考和記憶。用聽筒和聲敏元件作為耳朵能聽,用揚(yáng)聲器作為嘴能說話進(jìn)行應(yīng)答,用熱電偶和電阻應(yīng)變儀作為觸覺和感觸。用滾輪或者雙足式機(jī)構(gòu)腳來實(shí)現(xiàn)自動(dòng)移位。這樣的智能機(jī)械手可以由人的特殊
語言對其下達(dá)命令,布置任務(wù),使自動(dòng)化生產(chǎn)線成為智能化生產(chǎn)線。
(6)機(jī)械手的外觀達(dá)到美觀的要求,盡量用最簡單的結(jié)構(gòu)和設(shè)備能完成更加多的動(dòng)作。
(7)研制具有柔性系統(tǒng)的通用機(jī)械手
目前,在國外廣泛應(yīng)用的再現(xiàn)式通用機(jī)械手,雖然一般也都有記憶裝置,但其程序都是預(yù)先編好的,或由人在工作之前領(lǐng)動(dòng)一次,而后機(jī)械手可以按領(lǐng)動(dòng)的工作內(nèi)容正確進(jìn)行再現(xiàn)動(dòng)作。如果把這種再現(xiàn)式通用機(jī)械手稱為第二代機(jī)械手的話,那么現(xiàn)在處于研制階段的智能機(jī)械手就是第三代了?,F(xiàn)在研究的機(jī)械手正在朝著一種可以存儲(chǔ)大量的程序的并且可以改變并重新寫入程序的方向發(fā)展,而且機(jī)械手具有比原來的更多的自由度。機(jī)械手的研究和應(yīng)用在我國尚屬起步階段,就顯示出許多特殊的優(yōu)點(diǎn),展現(xiàn)了廣闊的應(yīng)用前景。對于工業(yè)機(jī)械手今后在我國的應(yīng)用和發(fā)展,建議做好以下工作:
(1) 加強(qiáng)機(jī)械手基礎(chǔ)性能的實(shí)驗(yàn)以及基礎(chǔ)理論研究,克服和解決制造技術(shù)及其它存在的問題。
(2) 改變目前機(jī)械手多用于冷加工的狀況,針對笨重,高溫,有毒,高粉塵,易燃易爆,單調(diào)等惡劣勞動(dòng)環(huán)境,有計(jì)劃,有步驟的推廣應(yīng)用和研制多種機(jī)械手,用于鑄,鍛,焊以及噴漆等工作中。
(3) 提高機(jī)械手運(yùn)動(dòng)速度。尤其是應(yīng)用于沖壓行業(yè)中的機(jī)械手,以適應(yīng)提高生產(chǎn)率和符合生產(chǎn)節(jié)拍的需要。要研究解決機(jī)械手的運(yùn)動(dòng)速度和緩沖,定位技術(shù)。
(4) 引進(jìn)國外先進(jìn)技術(shù),培養(yǎng)專門技術(shù)人才,普及機(jī)械手有關(guān)知識(shí)。
(5) 盡快的解決機(jī)械搜的定性設(shè)計(jì),定點(diǎn),定量生產(chǎn)以及配備件的生產(chǎn)和供應(yīng)問題,推進(jìn)機(jī)械手設(shè)計(jì)制造中的現(xiàn)代化(CAD/CAM),標(biāo)準(zhǔn)化,系列化工作,以滿足國內(nèi)外市場的需求。
工業(yè)機(jī)械手的種類很多,關(guān)于分類的問題,目前在國內(nèi)尚無統(tǒng)一的分類標(biāo)準(zhǔn),在此暫按使用范圍、驅(qū)動(dòng)方式和控制系統(tǒng)等進(jìn)行分類。
一、按用途分
機(jī)械手可分為專用機(jī)械手和通用機(jī)械手兩種:
1、專用機(jī)械手
它是附屬于主機(jī)的、具有固定程序而無獨(dú)立控制系統(tǒng)的機(jī)械裝置。專用機(jī)械手具有動(dòng)作少、工作對象單一、結(jié)構(gòu)簡單、使用可靠和造價(jià)低等特點(diǎn),適用于大批量的自動(dòng)化生產(chǎn)的自動(dòng)換刀機(jī)械手,如自動(dòng)機(jī)床、自動(dòng)線的上、下料機(jī)械手和“加工中心”。
2、通用機(jī)械手
它是一種具有獨(dú)立控制系統(tǒng)的、程序可變的、動(dòng)作靈活多樣的機(jī)械手。格性能范圍內(nèi),其動(dòng)作程序是可變的,通過調(diào)整可在不同場合使用,驅(qū)動(dòng)系統(tǒng)和控制系統(tǒng)是獨(dú)立的。通用機(jī)械手的工作范圍大、定位精度高、通用性強(qiáng),適用于不斷變換生產(chǎn)品種的中小批量自動(dòng)化的生產(chǎn)。通用機(jī)械手按其控制定位的方式不同可分為簡易型和伺服型兩種:簡易型以“開一關(guān)”式控制定位,只能是點(diǎn)位控制:可以是點(diǎn)位的,也可以實(shí)現(xiàn)連續(xù)軌跡控制,伺服型具有伺服系統(tǒng)定位控制系統(tǒng),一般的伺服型通用機(jī)械手屬于數(shù)控類型。
(二)按驅(qū)動(dòng)方式分
1、液壓傳動(dòng)機(jī)械手
是以液壓的壓力來驅(qū)動(dòng)執(zhí)行機(jī)構(gòu)運(yùn)動(dòng)的機(jī)械手。其主要特點(diǎn)是:抓重可達(dá)幾百公斤以上、傳動(dòng)平穩(wěn)、結(jié)構(gòu)緊湊、動(dòng)作靈敏。但對密封裝置要求嚴(yán)格,不然油的泄漏對機(jī)械手的工作性能有很大的影響,且不宜在高溫、低溫下工作。若機(jī)械手采用電液伺服驅(qū)動(dòng)系統(tǒng),可實(shí)現(xiàn)連續(xù)軌跡控制,使機(jī)械手的通用性擴(kuò)大,但是電液伺服閥的制造精度高,油液過濾要求嚴(yán)格,成本高。
2、氣壓傳動(dòng)機(jī)械手
是以壓縮空氣的壓力來驅(qū)動(dòng)執(zhí)行機(jī)構(gòu)運(yùn)動(dòng)的機(jī)械手。其主要特點(diǎn)是:介質(zhì)李源極為方便,輸出力小,氣動(dòng)動(dòng)作迅速,結(jié)構(gòu)簡單,成本低。但是,由于空氣具有可壓縮的特性,工作速度的穩(wěn)定性較差,沖擊大,而且氣源壓力較低,抓重一般在30公斤以下,在同樣抓重條件下它比液壓機(jī)械手的結(jié)構(gòu)大,所以適用于高速、輕載、高溫和粉塵大的環(huán)境中進(jìn)行工作。
3、機(jī)械傳動(dòng)機(jī)械手
即由機(jī)械傳動(dòng)機(jī)構(gòu)(如凸輪、連桿、齒輪和齒條、間歇機(jī)構(gòu)等)驅(qū)動(dòng)的機(jī)械手。它是一種附屬于工作主機(jī)的專用機(jī)械手,其動(dòng)力是由工作機(jī)械傳遞的。它的主要特點(diǎn)是運(yùn)動(dòng)準(zhǔn)確可靠,用于工作主機(jī)的上、下料。動(dòng)作頻率大,但結(jié)構(gòu)較大,動(dòng)作程序不可變。
4、電力傳動(dòng)機(jī)械手
即有特殊結(jié)構(gòu)的感應(yīng)電動(dòng)機(jī)、直線電機(jī)或功率步進(jìn)電機(jī)直接驅(qū)動(dòng)執(zhí)行機(jī)構(gòu)運(yùn)動(dòng)的械手,因?yàn)椴恍枰虚g的轉(zhuǎn)換機(jī)構(gòu),故機(jī)械結(jié)構(gòu)簡單。其中直線電機(jī)機(jī)械手的運(yùn)動(dòng)速度快和行程長,維護(hù)和使用方便。此類機(jī)械手目前還不多,但有發(fā)展前途。
(三)按控制方式分
1、點(diǎn)位控制
它的運(yùn)動(dòng)為空間點(diǎn)到點(diǎn)之間的移動(dòng),只能控制運(yùn)動(dòng)過程中幾個(gè)點(diǎn)的位置,不能控制其運(yùn)動(dòng)軌跡。若欲控制的點(diǎn)數(shù)多,則必然增加電氣控制系統(tǒng)的復(fù)雜性。目前使用的專用和通用工業(yè)機(jī)械手均屬于此類。
2、連續(xù)軌跡控制
它的運(yùn)動(dòng)軌跡為空間的任意連續(xù)曲線,其特點(diǎn)是設(shè)定點(diǎn)為無限的,整個(gè)移動(dòng)過程處于控制之下,可以實(shí)現(xiàn)平穩(wěn)和準(zhǔn)確的運(yùn)動(dòng),并且使用范圍廣,但電氣控制系統(tǒng)復(fù)雜。這類工業(yè)機(jī)械手一般采用小型計(jì)算機(jī)進(jìn)行控制。
一般固定程序的機(jī)械手,動(dòng)作比較簡單,自由度數(shù)較少。工業(yè)機(jī)器人自由度數(shù)較多,動(dòng)作靈活性和通用性較大。一般說來,機(jī)器人靠近機(jī)座的3個(gè)自由度是用來實(shí)現(xiàn)手臂末端的空間位置的,再用幾個(gè)自由度來定出末端執(zhí)行器的方位;7個(gè)以上的自由度是冗余自由度,是用來躲避障礙物的。
我做的是通用機(jī)械手,要求有較高的定位精度和較高的耐用度。結(jié)構(gòu)形式方案主要有:直角坐標(biāo)型,圓柱坐標(biāo)型,球坐標(biāo)型,關(guān)節(jié)型。
為了使機(jī)械手的通用性更強(qiáng),把機(jī)械手的手部結(jié)構(gòu)設(shè)計(jì)成可更換結(jié)構(gòu),當(dāng)工件是棒料時(shí),使用夾持式手部。如果有實(shí)際需要,還可以換成氣壓吸盤式結(jié)構(gòu)或電磁式吸盤結(jié)構(gòu)。手爪是機(jī)械手直接用下抓取和握緊(或吸附)工件夾持專用工具(如噴槍。扳子、焊接工具)進(jìn)行損作的部件。它具有模仿人手動(dòng)作的功能,,并安裝于機(jī)械手手臂的前端。手腕運(yùn)動(dòng)圖如圖3-1
3-1手腕運(yùn)動(dòng)示意圖
設(shè)計(jì)時(shí)考慮的幾個(gè)問題
(一)具有足夠的握力(即夾緊力)
在確定手指的握力時(shí),除考慮工件重量外,還應(yīng)考慮在傳送或操作過程中所產(chǎn)生的慣性力和振動(dòng),以保證工件不致產(chǎn)生松動(dòng)或脫落。
(二)手指間應(yīng)具有一定的開閉角
兩手指張開與閉合的兩個(gè)極限位置所夾的角度稱為手指的開閉角。手指的開閉角應(yīng)保證工件能順利進(jìn)入或脫開,若夾持不同直徑的工件,應(yīng)按最大直徑的工件考慮。對于移動(dòng)型手指只有開閉幅度的要求。
(三)保證工件準(zhǔn)確定位
為使手指和被夾持工件保持準(zhǔn)確的相對位置,必須根據(jù)被抓取工件的形狀,選擇相應(yīng)的手指形狀。例如圓柱形工件采用帶“V”形面的手指,以便自動(dòng)定心。
(四)具有足夠的強(qiáng)度和剛度
手指除受到被夾持工件的反作用力外,還受到機(jī)械手在運(yùn)動(dòng)過程中所產(chǎn)生的慣性力和振動(dòng)的影響,要求有足夠的強(qiáng)度和剛度以防折斷或彎曲變形,但應(yīng)盡量使結(jié)構(gòu)簡單緊湊,自重輕,并使手部的中心在手腕的回轉(zhuǎn)軸線上,以使手腕的扭轉(zhuǎn)力矩最小為佳。
(五)應(yīng)考慮被抓取對象的要求
1.抓取形狀 手指形狀應(yīng)根據(jù)工件形狀而設(shè)計(jì)。如工件為圓柱形.則采用“V”形
手指;圓球狀工件用圓弧形三指手指,方料用平面形手指,細(xì)絲工件用尖指勾形或細(xì)齒
鉗爪手指??傊畱?yīng)根據(jù)工件形狀來選定手指形狀。
2,抓取部位 抓取部位的尺寸盡可能是不變的.若加工后尺寸有變化,手指應(yīng)能適
應(yīng)尺寸變化的要求,否則不允許定為抓取部位。對于工件表面質(zhì)量要求高的,抓取時(shí)盡
量避開高質(zhì)量表面或在手指上加軟質(zhì)墊片(如橡皮.抱沫塑料.石棉襯墊等),以防夾持
時(shí)損壞工件。
3.抓取數(shù)量 若用一對手指抓取多個(gè)工件,為了不發(fā)生個(gè)別工件的松動(dòng)或脫落現(xiàn)
象,在手指上可增加彈性襯墊,如橡皮、泡沫、塑料等 ,對于較長工件可采用雙指或多指抓取。
(六)應(yīng)考慮手指的多用性
手指是專用性較強(qiáng)的部件,為適應(yīng)小批量多品種工件的不同形狀和尺寸的要求,可
制成組合式的手指,對于這種手指要求結(jié)構(gòu)簡單,安裝維修方便,更換迅速和準(zhǔn)確,以便擴(kuò)大機(jī)械手的使用范圍。
實(shí)習(xí)心得:本次實(shí)習(xí)了解了很多通用液壓機(jī)械手方面的知識(shí)。機(jī)械手應(yīng)用的十分廣泛,而我了解有限,設(shè)計(jì)方面大部分要依靠老師幫忙,還請老師多改正。