工业机器人及其系统组成—外文翻译.doc

附录英文原文Industrial Robot and its systems componentsThere are a variety of definitions of the term robot. Depending on the definition used, the number of robot installations worldwide varies widely. Numerous single purpose muchines are used in manufacturing plants that might appear to be robots. These machines are hardwired to perform a single function and can not be reprogrammed to perform a different function. Such single-purpose machines do not fit the definition for industrial robots that is becoming widely accepted. This definition was developed by the robot Institute ofAmerica:A robot is a reprogrammable muhifunctional manipulator designed to move material, parts, tools, or specialized devices through variable progranmled motions for the perfommnce of a variety of tasks.Note that this definition cxmtalns the words reprograrnmable and multifunctional. It is these two characteristics that separate the true industrial robot from the various single-purpose machines used in modern manufacturing firms. The termreprogrammableimplies two things:The robot operates aec)rding to a written program, and this program can be rewritten to acconlmodatc a variety of manufacturing tasks.The termmultifunctionalmeans that the robot can, through reprogramming and the use of different cnd-effectors, perform a number of different manufacturing tasks. Definitions written around these two critical characteristics are becoming the accepted definitions among manufacturing professionals.The fimt articulated arm came about in 1951 and was used by the U.S. Atomic Energy Commission. In 1954, the first programmable robot was designed by George Devol. It was based on two important technologies:(1) Numerical control (NC) technology.(2) Remote manipulation technology.Numerical control technology provided a foma of machine control ideally suited to robots.It allowed for the control of motion by stored programs. These programs contain data points to which the robot sequentially moves, timing signals to initiate action and to stop movement, and logic statements to allow for decision rfmking.Remote manipulation technology allowed a machine to be more than just another NC machine. It allowed such machines to become robots that can perfoml a variety of manufactuing tasks in both inaccessible an unsafe environmonts. By mering these two technologies, Devol developed the first industrial robot, an unsophistieated programmable materials handling machine.The first conunercially produced robot was developed in 1959. In 1962, thefirst industrial robot to be used oil a production llne was installed by GeneralMotors Corporation. This robot was produced by Unimation. A major step forwardin robot control occurred in 1973 with the development of the T-3 industrial robotby Cincinnati Milaeron. The T-3 robot was the first commercially produced industrial robot controlled by a minicomputer.Numerical control and remote manipulation technology prompted the wide scaledevelopment and use of industrial robots. But major technological developmentsdo not take place simply because of such new capabilities. Something must providethe impetus for taking advantage of these capabilities. In the case of industrialrobots, the impetus was economies.The rapid inflation of wages experienced in the 1970s tremendously increased the personnel costs of manufacturing firms. At the same time, foreign competition became a serious problem for U. S. manufacturers. Foreign manufacturers who had under taken automation on a wide scale basis, such as those in Japan, began to gain an increasingly large share of the U.S. and world market for manufactured goods, particularly automobiles.Through a variety of automation techniques, includicg robots, Japanese manufacturers, beginning in the 1970s, were able to produce better automobiles more cheaply than nonautomated U.S. manufacturers. Consequently, in order to survive, U.S. manufacturers were forced to consider any technological developmentsthat could help improve productivity.It became imperative to produce better produets at lower costs in order tobe competitive with foreign manufacturers. Other factors such as the need to findbetter ways of performing dangerous marmfacturing tasks contributed to thedevelopment of industrial robots. However, the principal rationale has always been,and is still, improved productivity.One of the principal advantages of robots is that they can be used in settingsthat are dangerous to humans. Welding and parting are examples of applicationswhere rotmts can be dangerous to humans. Even though robots are closely asmciatedwith safety in the workplace, they can, in themselves, be dangerous.Robots and robot cells must be carefully designed and configured so that they do not endanger human workers and other machines. Robot work envelops should be accurately calculated and a danger zone surroundting the envelop clearly marked off. Red flooring strips and barriers can be userd to keep human workers out of a robots work envelope.Eren with such precautions it is still a good idea to have an automatic shutdown system in situations where robots are used. Such a system should should have the capacity to sense the need for an automatic shutdown of operations. Fault-tolerant computers and redunant systems can be installed to ensure proper shutdown of robotics systems to ensure a safe environment.Industrial robots is the science of designing, building, and applying industrial robcts. What are robots? In the late 1970s the Robotic Industries Association defined a robot as” a manipulator, designed to move material, parts,tools or specialized devices through variable programmed motions for the performance of a variety of tasks. Although this definition does not directlyinclude pick and place arms as robots, teleoperamrs and remotely controlled devicesare often referred to also as robots. The International Standards Organization(ISO) has a more lengthy definition of an industrial robot:A machine formed by a mechanism including several degrees of freedom, often having tile appearanoa of one or several arms ending in a wrist capable of holding a tool or a workpiece or an inspection device. In particular, its control unit must use a memorizing device and .sometimes it can use sensing or adaptation appliances taking into account environment and circumstances. These multipurtpose machines are generally designed to carry out a repetitive function and can be adapted to other functions.The RIA and ISO definitions both stress the muLtifunctional and programmable capabilities and, therefore, exclude special-purpose hard automation tools and equipment typically found in high volume production. Also excluded are manual remote manipulators, which are extensions of human hands for use in, for example, sterile, hot, or radioactive environments.In Japan, the Japanese Industrial Robot Association (JIRA) classifies industrial robots by the method of input informatkm and the method of teaching:1. Manual Manipulators. Manipulators directly activated by the operator.2. Fixed-sequence Robot. Robot that once programmed for a given sequence of operations is not easily changed.3. Variable-sequence Robot. Robot that can be programmed for a given sequence of operations and can easily be changed or reprogrammed.4. Playback Robot. Robot that memorizes work sequences taught by a human being who physically leads the device through the intended work pattern; the robot can then create this sequence repetitively from memory.5. Numerically Controlled (NC) Robot. Robot that operatas from and is controlled by digital data, as in the form of punched tape, cards, or digital switches; operates like a NC machine.6. Intelligent Robot. Robot that uses sensory perception to evaluate its environment andcmake decisions and proceeds to operate accordingly.The first-generation of robot systems was defined for the various robots with limited computer power. Their main intelligant functions include programming by showing a sequence of manipulation steps by a human operator using a teach box. Without any sensors, these robots require a prearranged and relatively fixed factory environment and, therefore, have limited use.The second-generation of robot systems was enhanced by the addition of a computer processor. A major step in industrial robotics development was the integration of a computer with the industrial robot mechanism. This has provided real-time calculation of trajectory to smooth the motions of the end effector and integration of mine simple force and proximity sensors to obtain external signals.The main applications of second generation robots include spot and arc welding, spray painting, and some assembly.Third-generation robot systems incorporate multiple eomputer processors and multiple arms that can operate asynchronously to perform .several functions. Distributed hierarchical mmputer organization is preferred, because it can coordinate motions and interface with external sensors, other machines, and other robots and can communicate with other computers. These robots can already exhibit intelligent behavior, including knowledge-based control and learning abilities.Japan ranks as the worlds top robot-producing and robot-using country, with more than 40% of the worlds industrial robot installations. The reasons for this penetration are sociological-and technological factors that are unique to Japan:industrial robots brought productivity and quality gains in Japanese industry, coupled with improvements of the work enviromnent. These have perpetuated the social-demand for more robots as well as increased the expectation from this technology.Current and emerging robot applications in industry can be categorized on the complexity and requirements of the job. They range from simple, low technolngy pick-and place operations through medium technology painting, some assembly and welding operations to high technology precision assembly and inspection operations.Pick-and-place Operations The earliest applications of robots were in machine loading unloading, pick-and-place, and material transfer operations. Such robots typically were not servo controlled and worked with pneumatic or hydraulic power. The Icxad-carrying requirements were high, working in dirty or hazardous factory environments. Replacing unskilled human labor often in hazardous jobs, these robots had to be robust and low in initial and maintenance costs.Painting and Welding Operations The next level in the sophistimtion of industrial robot applications was in spray painting, and spot and arc welding. These applications complemented or replaced certain skilled human labor. Often the justification was by eliminating dangerous environmental exposures. These applications often require tracking complex trajectories such as painting surface mntours, hence mrvo controlled articulated or spherical robot structures were used.Lead-through teaching modes became commom, and sometimes sophisticated sensors are employed to maintain process consistency. Experience has shown that when properly selected and implemented, thase robotic applications usually lead to reduced overall manufacturing costs and improved product quality compared with manual method.Assembly Operations The most advanced level of technology employing third-generation industrial robots is found in assembly. System repeatability is of utmost importance. End-of-arm tooling must be compliant, i.e., have both force and displacement control to adjust part insertions, which require that the robot actually feel its way along. This technology usually requires a measure of artificial intelligence. Assembly robots generally are electronically driven and operate in clean enviromnents. Assembly robots are expected to exceed further technology applications.Other Applications Other typical applications of robots include inspection, quality control, and repair; processing such as laser and water jet cutting and drilling, riveting, and clean room operations; and applications in the wood, paper, and food-processing industries. As industrial robot technology and robot intelligence improve even further, additional applications may be justified effectively.The components of a robot system could be discussed either from a physical point of view or from a systems point of view. Physically, we would divide the system into the robot, power system, and controller (computer). Likewise, the robot itself could be partitioned anthropomorphically into base, shoulder, elbow, wrist, gripper, and tool. Most of these terms require little explanation.Consequently, we will describe the components of a robot system from the point of view of information transfer. That is, what infomtation or signal enters the component; what logical or arithmetic operation does the component perform; and what information or signal does the component produce? It is important to note that the same physical component may perform many different information proees.sirkg operations (e. g. , a central computerperforms many different calculations on different data). Likewise, two physically separate components may perform identical information operations ( e. g., the shoulder and elbow actuators both convert signals to motion in very similar ways).Actuator Asmciated with each joint on the robot is an actuator which causes that joint to move. Typical actuators are electric motors and hydraulic cylinders. Typically, a robot system will contain six actuators, since six are required for full control of position and orientation. Many robot applications do not require this full flexibility, and consequently, robots are often built with five or fewer actuators.Sensor To control an actuator, the computer must have infommtion regarding the position and possibly the velocity of the actuator. In this context, the term position refers to a displacement from some arbitrary zero reference point for that actuator. For example, in the case of a rotary actuator , position would really the angular position and be measured in radians.Many types of sensors can provide indications of position and velocity. The various types of sensors require different mechanisms for interfacing to the computer. In addition, the industrial use of the manipulator requires that the interface be protected from the harsh electrical environment of the factory. Sources of electrical noise such as arc welders and large motors can easily makena digital system useless unless care is taken in design and construction of the interface.Computation We could easily have labeled the computation module computer,as most of the Functions to be described are typically perfommd by digital computers. However, many of the Functions may be performed in dedicated custom hardware or networks of computers We will, thus, discuss the commputational component as if it were a simple computer, recognizing that tile need for real-time control may require special equipment and that some of this equipment may even be analog, although the current trend is toward fully digital systems.One further note: We will tend to avoid the use of the term microprocessor in this book and simply say computer, although many current robot manufacturers use one or more microprocessors in their systems.The computation component performs the following operations: Servo Given the current position and/or velocity of an actuator, determine the appropriate drive signal to move that actuator toward its desired position. This operation must be performed for eaeh actuator. Kinematics Given the current statel of the actuators (position and velocity ),determine the current state of the gripper. Conversely, given a desired state of the hand, determine the desired state for each actuator.Dynamics Given knowledge of the loads on the arm (inertia, friction, gravity, acceleration), use this information to adjust the sorvo operation to achieve better performance.Workplace Sensor Analysis Given knowledge of the task to be performed, determine appropriate robot motion commands. This nmy include analyzing a TV picture of the workplace or measuring and compensating for forces applied at the hand.In addition to these easily identified co. mponents, there are also supervisory operations such as path planning and operator interaction.中文翻译工业机器人及其系统组成有许多关于机器人这个术语的定义。采用不同的定义，全世界各地机器人的数量就会发生很大的变化。在制造T 厂中使用的许多单用途机器可能会看起来像机器人。这些机器是硬连线的，不能通过新编程的方式去完成不同的工作。这种单用途的机器不能满足被人们日益广泛接受的关于工业机器人的定义。这个定义是由美国机器人协会提出的：机器人是一个以改编程序的多功能操作器，被设计涉及用束按照预先编制的、能够完成多种作业的运动程序运送材料、零件、工具或者专用设备。注意在这个定义中包含“可以改编程序”和“多功能”这两个词。正是这两个词将真证的机器人与现代制造工厂中使用的单一用途的机器区分开来。“可以改编程序”这个术语意味着两件事：机器人根据编写的程序工作，以及可以通过重新编写程序来适应不同种类的制造工作的需要。“多功能”这个词意味着机器人能够通过编程和使用的末端执行机构，完成不同的制造上作。围绕着这两个关键特征所撰写的定义正在变成制造业的专业人员所接受的定义。第一个带有活动关节的于臂于1951年被研制出来，由美国原子能委员会使用。在1954年，第一个可以编程的机器人由乔治狄弗设计出来。它基于下面两项重要技术：(1)数字控制(NC)技术；(2)远程操作技术。数字控制技术提供一种非常适合于机器人的机器控制技术。它可通过存储的程序对运动进行控制。这些程序包含机器人进行顺序运动的数据，开始运动和停止运动的时间控制信号，以及做出决定所需要的逻辑语句。远程操作技术使得一台机器的性能超出一台数控机器。它可以使这种机器能够在不容易进入和不安全的环_徉_境中完成各种制造任务。通过融合上述两项技术，狄弗研制出第一个机器人，它是一个不复杂的，可以编程的物料运送机器人。第-台商业化生产的机器人在1959年研制成功。通用汽车公司在1962 年安装了第一台用于生产线上的工业机器人，它是尤尼梅森公刊生产的。在1973 年，辛辛哪挺米兰克朗公司研制出T 3 工业机器人，存机器人的控制方面取得r 较大的进展。T 3 机器人是第一台商业化生产的采用计算机控制的机器人。数字控制技术和远程操作技术推动了大范围的机器人研制和应用。但是主要的技术进步并不仅仅是由于这些新的应用能力而产生的，而是必须由利用这些能力所得到的效益来提供动力。就工业机器人而古，这个动力是经济件。在 20 世纪70 年代中，丁资的快速增长大大增加了制造业的企业中的人工费用。与此同时，来自国外的竞争成为美国制造业所面临的一个严峻的考验。诸如日本等外国的制造厂家在广泛地应用自动化技术之后，其工业产晶，特别是汽车，在美国和世界市场上占据了日益增大的份额。通过采用包括机器人在内的各种自动化技术，从20世纪70 年代开始，口本的制造厂家能够比没有采用自动化技术的美国制造厂家生产更好的和便宜的汽车。随后，为了生存，美国制造厂家被迫考虑采用任何能够提高生产率的技术。为了与国外制造厂家进行竞争，必须以比较低的成术，生产出更好的产品。其他的因素，诸如寻找能够更好地完成带有危险性的制造工作的方式也促进了工业机器人的发展。但是，主要的理由一直是，而日现在仍然是提高生产率。机器人的一个主要优点是它们可以在对于人类来说是危险的位置上工作。采用机器人进行焊接和切断工作是比由人工来完成这些工作更安全的例子。尽管机器人与工作地点的安全密切相关，它们本身也可能是危险的。应该仔细地设计和配置机器人和机器人单元，使它们不会伤害人类和其他机器。应该精确地算出机器人的工作范围，且在这个范围的四周