四自由度棒料搬運機械手設計-氣動機械手[圓柱坐標型 2KG]
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編號
無錫太湖學院
畢業(yè)設計（論文）
相關資料
題目： 四自由度棒料搬運機械手設計
信機 系 機械工程及其自動化 專業(yè)
學 號： 0923076
學生姓名： 陳 華
指導教師： 馮 鮮（職稱：講 師 ）
（職稱： ）
2013年5月25日
目 錄
一、畢業(yè)設計（論文）開題報告
二、畢業(yè)設計（論文）外文資料翻譯及原文
三、學生“畢業(yè)論文（論文）計劃、進度、檢查及落實表”
四、實習鑒定表
無錫太湖學院
畢業(yè)設計（論文）
開題報告
題目： 四自由度棒料搬運機械手設計
機電系 機械工程及其自動化 專業(yè)
學 號： 0923076
學生姓名： 陳 華
指導教師： 馮 鮮 （職稱：講 師 ）
（職稱： ）
2012年11月26日
課題來源
隨著世界經(jīng)濟的快速發(fā)展和現(xiàn)代科學技術的進步,物流產(chǎn)業(yè)作為國民經(jīng)濟中一個新興的服務部門,正在全球范圍內(nèi)迅速發(fā)展.在國際上,物流產(chǎn)業(yè)被認為是國民經(jīng)濟發(fā)展的動脈和基礎產(chǎn)業(yè),其發(fā)展程度成為衡量一國現(xiàn)代化程度和綜合國力的重要標志之一,被喻為促進經(jīng)濟發(fā)展的“加速器”.物流產(chǎn)業(yè)是指鐵路、公路、水路、航空等基礎設施,以及工業(yè)生產(chǎn)、商業(yè)批發(fā)零售和第三方倉儲運輸及綜合物流企業(yè)為實現(xiàn)商品的實體位移所形成的產(chǎn)業(yè).國民經(jīng)濟各個領域的物流經(jīng)濟實體從橫向構成了物流產(chǎn)業(yè).這個產(chǎn)業(yè)由鐵道、公路、水運、空運、倉儲、托運等行業(yè)為主體組成,同時還包含了商業(yè)、物資業(yè)、供銷、糧食、外貿(mào)等行業(yè)中的一半領域,還涉及到機械、電器業(yè)中的物流裝備生產(chǎn)行業(yè)和國民經(jīng)濟所有行業(yè)的供應、生產(chǎn)、銷售中的物流活動。
近年來工業(yè)自動化的發(fā)展機械器件逐漸成為一門新興的學科,并得到了較快的發(fā)展。工業(yè)現(xiàn)場的很多重體力勞動必將由機器代替,這一方面可以減輕工人的勞動強度,另一方面可以大大提高勞動生產(chǎn)率。例如,目前在我國的許多中小型生產(chǎn)行業(yè)中,往往沖壓成形這一工序還需人工上下料,既費時費力,又影響效率。為此我們研制了一套上下料機械手模擬裝置，以此為基礎,為進一步實用化做好充分準備。機械手是工業(yè)自動控制領域中經(jīng)常遇到的一種控制對象. 是一種模仿人手動作，并按設定程序，軌跡和要求代替人手抓（吸）取，搬運工件或工具進行操作的自動化裝置。其可以完成許多工作,如搬物、裝配、切割、噴染等等,應用面非常廣泛。工業(yè)生產(chǎn)中常用的進行水平/垂直位移的機械設備的動作由氣缸驅動，氣缸又又相應的電磁閥控制，該機械手除外形尺寸比實物小些以外,其結構、原理及功能與實際的機械手是完全一致的。
科學依據(jù)
機器人（又稱機械手，機械人，英文名稱：Robot），在人類科技發(fā)展史上其來有自，早在三國時代，諸葛亮發(fā)明的木牛流馬即是古代中國人的智能結晶。隨著近代的工業(yè)革命，機器產(chǎn)業(yè)的不斷發(fā)展成為近代工業(yè)的主要支柱。
機器人的研究從一開始就是擬人化的，所以才有機械手、機械臂的開發(fā)與制作，也是為了以機械來代替人去做人力所無法完成的勞作或探險。但近十幾年來，機器人的開發(fā)不僅越來越優(yōu)化，而且涵蓋了許多領域，應用的范疇十分廣闊。
工業(yè)機器人是典型的機電一體化高技術產(chǎn)品。在許多生產(chǎn)領域，它對于提高生產(chǎn)自動化水平，提高勞動生產(chǎn)率、產(chǎn)品質量和經(jīng)濟效益，改善工人勞動條件的作用日見顯著。不少勞動條件惡劣、生產(chǎn)要求苛刻的場合，工業(yè)機器人代替人力勞動已是必然的趨勢。
工業(yè)機器人是一種機體獨立，動作自由度較多，程序可靈活變更，能任意定位，自動化程度高的自動操作機械。主要用于加工自動線和柔性制造系統(tǒng)中傳遞和裝卸工件或夾具。工業(yè)機器人以剛性高的手臂為主體，與人相比，可以有更快的運動速度，可以搬運更重的東西，而且定位精度相當高，它可以根據(jù)外部來的信號，自動進行各種操作。
國內(nèi)現(xiàn)狀及發(fā)展趨勢 物流這一概念的形成和物流管理學科的建立只不過幾十年的歷史,引入我國也僅十幾年時間。但是物流這一概念賴以形成的流通行業(yè)卻已歷史久遠,早在人類社會出現(xiàn)商品交換的時期就已經(jīng)出現(xiàn)了。隨著時間的流逝，物流的發(fā)展趨勢大致可以歸納為以下幾點： ①物流需求彈性逐年增高,經(jīng)濟增長越來越依賴于物流的發(fā)展。 ②第三方物流的比重逐年增加。 ③進一步加快國際化進程。④ 物流體系綜合化； ⑤ 三流一體化。
國外機械手工業(yè)、鐵路工業(yè)中不僅在單機、專機上采用機械手上下料，減輕工人的勞動強度，而且在鐵路工業(yè)中應用機械手以加工鐵路車軸、輪等大、中批零件。并和機床共同組成一個綜合的數(shù)控加工系統(tǒng)。采用機械手進行裝配更始目前研究的重點，國外已研究采用攝象機和力傳感裝置和微型計算機連在一起，能確定零件的方位達到鑲裝的目的。
國外機械手的發(fā)展趨勢是大力研制具有某種智能的機械手。使它具有一定的傳感能力，能反饋外界條件的變化，作相應的變更。視覺功能即在機械手上安裝有電視照相機和光學測距儀（即距離傳感器）以及微型計算機。 觸覺功能即是在機械手上安裝有觸覺反饋控制裝置。工作時機械手首先伸出手指尋找工作，通過安裝在手指內(nèi)的壓力敏感元件產(chǎn)生觸覺作用，然后伸向前方，抓住工件。 總之，隨著傳感技術的發(fā)展機械手裝配作業(yè)的能力也將進一步提高。更重要的是將機械手、柔性制造系統(tǒng)和柔性制造單元相結合，從而根本改變目前機械制造系統(tǒng)的人工操作狀態(tài)。
研究內(nèi)容
本設計中的四自由度棒料搬運機械手，主要是針對圓形棒料的搬運。
本設計中的機械手有四個自由度，由底座的旋轉，手臂的升降，手臂的伸縮，手爪 的旋轉組成。本設計中的機械手是一種通用型棒料搬運機械手。
通過氣爪手指的不同選擇可滿足不同直徑的棒料的搬運。通過示教再現(xiàn)或程序的直接控制可實現(xiàn)在機械手工作范圍內(nèi)把棒料從指定點搬運到另一指定點，并把棒料翻轉過來。通過對機械手的相應控制還可實現(xiàn)對棒料的排列。
擬采取的研究方法、技術路線、實驗方案及可行性分析
由設計要求本設計機械手實現(xiàn)的作用：自動線上有A,B兩條輸送帶，之間距離為0.7米，現(xiàn)設計機械手將一棒料翻轉過來。
確定為四自由度的機械手。其中2個為旋轉，兩個為平移。
在工業(yè)機器人的諸多功能中，抓取和移動是最只要的功能。這兩項功能的實現(xiàn)的技術基礎是精巧的機械結構設計和良好的伺服控制驅動。
本次設計就是在這一思維下展開的。根據(jù)設計內(nèi)容和需求確定機械手，利用步進電機驅動和諧波齒輪傳動來實現(xiàn)機器人的旋轉運動；利用另一臺步進電機驅動滾珠絲杠旋轉，從而使與滾珠絲杠螺母副固連在一起的手臂實現(xiàn)上下運動；考慮到本設計中的機械手工作范圍不大，故利用氣缸驅動實現(xiàn)手臂的伸縮運動；末端夾持器則選用氣爪來做夾持器，用小型氣缸驅動夾緊。氣爪的旋轉則由與氣爪連接的擺動氣缸實現(xiàn)。
研究計劃及預期成果
研究計劃：
2012年11月12日~2012年11月18日：按照任務書要求查閱論文相關參考資料，填寫畢業(yè)設計開題報告書。
2012年11月19日~2012年11月24日：填寫畢業(yè)實習報告。
2012年11月25日~2012年12月2日：按照要求修改畢業(yè)設計開題報告。
2013年12月3日~2013年12月17日：學習并翻譯一篇與畢業(yè)設計相關的英文材料。
2013年1月11日～2013年1月15日：PLC程序設計。
2013年1月21日~2013年2月2日：CAD設計。
2013年3月6日~2013年5月25日：畢業(yè)論文撰寫和修改工作。
預期成果：
通過氣爪手指的不同選擇可滿足小于直徑60mm的棒料的搬運。通過示教再現(xiàn)或程序的直接控制可實現(xiàn)在機械手工作范圍內(nèi)把棒料從指定點搬運到另一指定點，并把棒料翻轉過來。通過對機械手的相應控制還可實現(xiàn)對棒料的排列。
特色或創(chuàng)新之處
采用多自由度，可一定程度的模擬人手動作。
可配合一些簡單的工具并行使用。
已具備的條件和尚需解決的問題
機械爪通用性不強，有一定的限制。
指導教師意見
指導教師簽名：
年 月 日
教研室（學科組、研究所）意見
教研室主任簽名：
年 月 日
系意見
主管領導簽名：
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英文原文
Spin control for cars
Stability control systems are the latest in a string of technologies focusing on improved diriving safety. Such systems detect the initial phases of a skid and restore directional control in 40 milliseconds, seven times faster than the reaction time of the average human. They correct vehicle paths by adjusting engine torque or applying the left- or-right-side brakes, or both, as needed. The technology has already been applied to the Mercedes-Benz S600 coupe.
Automatic stability systems can detect the onset of a skid and bring a fishtailing vehicle back on course even before its driver can react.
Safety glass, seat belts, crumple zones, air bags, antilock brakes, traction control, and now stability control. The continuing progression of safety systems for cars has yielded yet another device designed to keep occupants from injury. Stability control systems help drivers recover from uncontrolled skids in curves, thus avoiding spinouts and accidents.
Using computers and an array of sensors, a stability control system detects the onset of a skid and restores directional control more quickly than a human driver can. Every microsecond, the system takes a "snapshot," calculating whether a car is going exactly in the direction it is being steered. If there is the slightest difference between where the driver is steering and where the vehicle is going, the system corrects its path in a split-second by adjusting engine torque and/or applying the cat's left- or right-side brakes as needed. Typical reaction time is 40 milliseconds - seven times faster than that of the average human.
A stability control system senses the driver's desired motion from the steering angle, the accelerator pedal position, and the brake pressure while determining the vehicle's actual motion from the yaw rate (vehicle rotation about its vertical axis) and lateral acceleration, explained Anton van Zanten, project leader of the Robert Bosch engineering team. Van Zanten's group and a team of engineers from Mercedes-Benz, led by project manager Armin Muller, developed the first fully effective stability control system, which regulates engine torque and wheel brake pressures using traction control components to minimize the difference between the desired and actual motion.
Automotive safety experts believe that stability control systems will reduce the number of accidents, or at least the severity of damage. Safety statistics say that most of the deadly accidents in which a single car spins out (accounting for four percent of all deadly collisions) could be avoided using the new technology. The additional cost of the new systems are on the order of the increasingly popular antilock brake/traction control units now available for cars.
The debut of stability control technology took place in Europe on the Mercedes-Benz S600 coupe this spring. Developed jointly during the past few years by Robert Bosch GmbH and Mercedes-Benz AG, both of Stuttgart, Germany, Vehicle Dynamics Control (VDC). in Bosch terminology, or the Electronic Stability Program (ESP), as Mercedes calls it, maintains vehicle stability in most driving situations. Bosch developed the system, and Mercedes-Benz integrated it into the vehicle. Mercedes engineers used the state-of-the-art Daimler-Benz virtual-reality driving simulator in Berlin to evaluate the system under extreme conditions, such as strong crosswinds. They then put the system through its paces on the slick ice of Lake Hornavan near Arjeplog, Sweden. Work is currently under way to adapt the technology to buses and large trucks, to avoid jack-knifing, for example.
Stability control systems will first appear in mid-1995 on some European S-Class models and will reach the U.S. market during the 1996 model year (November 1995 introduction). It will be available as a $750 option on Mercedes models with V8 engines, and the following year it will be a $2400 option on six-cylinder $1650 of the latter price is for the traction control system, a prerequisite for stability control.
Bosch is not alone in developing such a safety system. ITT Automotive of Auburn Hills, Mich., introduced its Automotive Stability Management System (ASMS) in January at the 1995 North American International Auto Show in Detroit. "ASMS is a quantum leap in the evolution of antilock brake systems, combining the best attributes of ABS and traction control into a total vehicle dynamics management system," said Timothy D. Leuliette, ITT Automotive's president and chief executive officer.
"ASMS monitors what the vehicle controls indicate should be happening, compares that to what is actually happening, then works to compensate for the difference," said Johannes Graber, ASMS program manager at ITT Automotive Europe. ITT's system should begin appearing on vehicles worldwide near the end of the decade, according to Tom Mathues, director of engineering of Brake & Chassis Systems at ITT Automotive North America. Company engineers are now adapting the system to specific car models from six original equipment manufacturers.
A less-sophisticated and less-effective Bosch stability control system already appears on the 1995 750iL and 850Ci V-12 models from Munich-based BMW AG. The BMW Dynamic Stability Control (DSC) system uses the same wheel-speed sensors as traction control and standard anti-lock brake (ABS) systems to recognize conditions that can destabilize a vehicle in curves and corners. To detect such potentially dangerous cornering situations, DSC measures differences in rotational speed between the two front wheels. The DSC system also adds a sensor for steering angle, Utilizes an existing one for vehicle velocity, and introduces its own software control elements in the over allantilock-brake/traction-control/stability-control system.
The new Bosch and ITT Automotive stability control systems benefit from advanced technology developed for the aerospace industry. Just as in a supersonic fighter, the automotive stability control units use a sensor-based computer system to mediate between the human controller and the environment - in this case, the interface between tire and road. In addition, the system is built around a gyroscopelike sensor design used for missile guidance.
Beyond abs and traction control
Stability control is the logical extension of ABS and traction control, according to a Society of Automotive Engineers paper written by van Zanten and Bosch colleagues Rainer Erhardt and Georg Pfaff. Whereas ABS intervenes when wheel lock is imminent during braking, and traction control prevents wheel slippage when accelerating, stability control operates independently of the driver's actions even when the car is free-rolling. Depending on the particular driving situation, the system may activate an individual wheel brake or any combination of the four and adjust engine torque, stabilizing the car and severely reducing the danger of an uncontrolled skid. The new systems control the motion not only during full braking but also during partial braking, coasting, acceleration, and engine drag on the driven wheels, circumstances well beyond what ABS and traction control can handle.
The idea behind the three active safety systems is the same: One wheel locking or slipping significantly decreases directional stability or makes steering a vehicle more difficult. If a car must brake on a low-friction surface, locking its wheels should be avoided to maintain stability and steerability.
Whereas ABS and traction control prevent undesired longitudinal slip, stability control reduces loss of lateral stability. If the lateral forces of a moving vehicle are no longer adequate at one or more wheels, the vehicle may lose stability, particularly in curves. What the drive "fishtailing" is primarily a turning or spinning around the vehicle's axis. A separate sensor must recognize this spinning, because unlike ABS and traction control, a car's lateral movement cannot be calculated from its wheel speeds.
Spin handlers
The new systems measure any tendency toward understeer (when a car responds slowly to steering changes), or over-steer (when the rear wheels try to swing around). If a car understeers and swerves off course when driven in a curve, the stability control system will correct the error by braking the inner (with respect to the curve) rear wheel. This enables the driver, as in the case of ABS, to approach the locking limit of the road-tire interface without losing control of the vehicle. The stability control system may reduce the vehicle's drive momentum by throttling back the engine and/or by braking on individual wheels. Conversely, if the hteral stabilizing force on the rear axle is insufficient, the danger of oversteering may result in rear-end breakaway or spin-out. Here, the system acts as a stabilizer by applying the outer-front wheel brake.
The influence of side slip angle on maneuverability, the Bosch researchers explained, shows that the sensitivity of the yaw moment on the vehicle, with respect to changes in the steering angle, decreases rapidly as the slip angle of the vehicle increases. Once the slip angle grows beyond a certain limit, the driver has a much harder time recovering by steering. On dry surfaces, maneuverability is lost at slip-angle values larger than approximately 10 degrees, and on packed snow at approximately 4 degrees.
Most drivers have little experience recovering from skids. They aren't aware of the coefficient of friction between the tires and the road and have no idea of their vehicle's lateral stability margin. When the limit of adhesion is reached, the driver is usually caught by surprise and very often reacts in the wrong way, steering too much. Oversteering, ITT's Graber explained, causes the car to fishtail, throwing the vehicle even further out of control. ASMS sensors, he said, can quickly detect the beginning of a skid and momentarily activate the brakes at individual wheels to help return the vehicle to a stable line.
It is important that stability control systems be user-friendly at the limit of adhesion - that is, to act predictably in a way similar to normal driving.
The biggest advantage of stability control is its speed - it can respond immediately not only to skids but also to shifting vehicle conditions (such as changes in weight or tire wear) and road quality. Thus, the systems achieve optimum driving stability by changing the lateral stabilizing forces.
For a stability control system to recognize the difference between what the driver wants (desired course) and the actual movement of the vehicle (actual course), current cars require an efficient set of sensors and a greater computer capacity for processing information.
The Bosch VDC/ESP electronic control unit contains a conventional circuit board with two partly redundant microcontrollers using 48 kilobytes of ROM each. The 48-kB memory capacity is representative of the large amount of "intelligence" required to perform the design task, van Zanten said. ABS alone, he wrote in the SAE paper, would require one-quarter of this capacity, while ABS and traction control together require only one half of this software capacity.
In addition to ABS and traction control systems and related sensors, VDC/ESP uses sensors for yaw rate, lateral acceleration, steering angle, and braking pressure as well as information on whether the car is accelerating, freely rolling, or braking. It obtains the necessary information on the current load condition of the engine from the engine controller. The steering-wheel angle sensor is based on a set of LED and photodiodes mounted in the steering wheel. A silicon-micromachine pressure sensor indicates the master cylinder's braking pressure by measuring the brake fluid pressure in the brake circuit of the front wheels (and, therefore, the brake pressure induced by the driver).
Determining the actual course of the vehicle is a more complicated task. Wheel speed signals, which are provided for antilock brakes/traction control by inductive wheel speed sensors, are required to derive longitudinal slip. For an exact analysis of possible movement, however, variables describing lateral motion are needed, so the system must be expanded with two additional sensors - yaw rate sensors and lateral acceleration sensors.
A lateral accelerometer monitors the forces occurring in curves. This analog sensor operates according to a damped spring-mass mechanism, by which a linear Hall generator transforms the spring displacement into an electrical signal. The sensor must be very sensitive, with an operating range of plus or minus 1.4 g.
Yaw rate gyro
At the heart of the latest stability control system type is the yaw rate sensor, which is similar in function to a gyroscope. The sensor measures the speed at which the car rotates about its vertical axis. This measuring principle originated in the aviation industry and was further developed by Bosch for large-scale vehicle production. The existing gyro market offers two widely different categories of devices: $6000 units for aerospace and navigation systems (supplied by firms such as GEC Marconi Avionics Ltd., of Rochester, Kent, U.K.) and $160 units for videocameras. Bosch chose a vibrating cylinder design that provides the highest performance at the lowest cost, according to the SAE paper. A large investment was necessary to develop this sensor so that it could withstand the extreme environmental conditions of automotive use. At the same time, the cost for the yaw rate sensor had to be reduced so that it would be sufficiently affordable for vehicle use.
The yaw rate sensor has a complex internal structure centered around a small hollow steel cylinder that serves as the measuring element. The thin wall of the cylinder is excited with piezoelectric elements that vibrate at a frequency of 15 kilohertz. Four pairs of these piezo elements are arranged on the circumference of the cylinder, with paired elements positioned opposite each other. One of these pairs brings the open cylinder into resonance vibration by applying a sinusoidal voltage at its natural frequency to the transducers; another pair, which is displaced by 90 degrees, stabilizes the vibration. At both element pairs in between, so-called vibration nodes shift slightly depending on the rotation of the car about its vertical axis. If there is no yaw input, the vibration forms a standing wave. With a rate input, the positions of the nodes and antinodes move around the cylinder wall in the opposite direction to the direction of rotation (Coriolis acceleration). This slight shift serves as a measure for the yaw rate (angular velocity) of the car.
Several drivers who have had hands-on experience with the new systems in slippery cornering conditions speak of their cars being suddenly nudged back onto the right track just before it seems that their back ends might break away.
Some observers warn that stability controls might lure some drivers into overconfidence in low-friction driving situations, though they are in the minority. It may, however, be necessary to instruct drivers as to how to use the new capability properly. Recall that drivers had to learn not to "pump" antilock brake systems.
Although little detail has been reported regarding next-generation active safety systems for future cars (beyond various types of costly radar proximity scanners and other similar systems), it is clear that accident-avoidance is the theme for automotive safety engineers. "The most survivable accident is the one that never happens," said ITT's Graber. "Stability control technology dovetails nicely with the tremendous strides that have been made to the physical structure and overall capabilities of the automobile." The next such safety system is expected to do the same.
中文譯文
汽車的轉向控制
控制系統(tǒng)穩(wěn)定性是針對提高駕駛安全性提出的一系列措施中最新的一個。這個系統(tǒng)能夠在40毫秒內(nèi)實現(xiàn)從制動開始到制動恢復的過程，這個時間是人的反應時間得七倍。他們通過調整
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