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机器人1960年初，约瑟夫恩格柏格和乔治迪沃尔联合创建一个机器人公司美国通用机械公司，从此工业机器人开始变为现实。机器人并不只是另一种自动化机器。自动化始于工业革命期间，用机器来完成先前人工完成的工作。然而，这种自动化机器仅仅能做到为它设计的特定工作，而机器人能执行各种各样的工作。机器人必须有一对手臂。在装卸自动化机器、喷漆、焊接时，手臂必须能够复制人类工人的动作，并且能成千上百次完成传统自动化机器不能完成的工作。机器人的定义机器人工业协会(RIA)发表了一个机器人的定义，试图阐明哪些机器仅仅是自动化机械，哪些机器才是真正的机器人。RIA的定义如下：机器人是一种可重新编程的多功能机械手，为实现各种任务设计成通过可改变的程序动作来移动材料、零部件、工具、或专门装置。这个定义比本书末尾RIA术语汇编的定义更加广泛，是更合适机器人的定义。当我们看到这个短语的定义，我们会了解哪些机械是真正的机器人而哪些机械只是专用自动化机器。首先，机器人是“可重编程的多功能操纵手”。RIA的这句话告诉我们，机器人可以通过改变其内存中存储的信息进行示教（重编程）使机器人做不同的工作。可对机器人重新编程，使其装卸自动化机器、喷漆、焊接以及做许多其他的工作（多功能）。机器人是“机械手”。机械手是手臂（或手）可以拿起或移动物品，在这一点上，我们知道，机器人是一个可以示教从而做各种不同工作的机械手臂。定义说，机器人“设计成通过可改变的程序动作来移动材料、零部件、工具、或专门装置。”材料包括木材、钢材、塑料、纸板.在制造产品使用的任何材料。机器人也可以处理已加工完成的零部件。例如，机器人可以将一块钢装入数控车床，并卸出车床中已加工完成的零件。除了处理材料和零部件，机器人还可以安装如磨床、缓冲器、螺丝刀、焊枪等工具来执行有效的工作。在制造工厂中机器人也可以配备专门的仪器或设备来完成特殊的工作。机器人可以安装摄像机来检验零件或产品。也可以配备激光器来精确测量正在加工的零件的尺寸。RIA的定义用“通过可改变的程序动作来完成各种不同操作”这句话进行结尾，这句话强调的事实是：在制造工厂，机器人可以做许多不同的工作。机器人能做的工作种类只受限于应用工程师的创造性。机器人的工作由机器人完成的工作可分为两大类：危险性工作和重复性工作。危险性工作 许多机器人应用于对人类有危险的工作。这些工作因为有毒气体、较重材料的处理、高温材料的处理、在旋转或冲压机械旁工作或环境中含有高浓度的辐射而被认为是危险的工作。重复性工作 除了担任危险的工作外，机器人也非常适合做那些在制造工厂里必须做的完全重复的工作。许多工厂的工作要求一个人表现得更像一个机器，而不像一个人类。这项工作可能要将一个工件从这里取起并把它放到那里。同样的工作每一天都要做上百次。这个工作对判断力和能力要求较少。这并不是批评做这份工作的人,而是仅仅指出这些工作存在于许多行业，并且必须完整的完成产品的制作。机器人可以在这样的工作情况下工作，并且不会抱怨和经受与这些工作相关的疲劳和厌倦。机器人的速度虽然机器人提高了制造工厂的生产率，但是他们也并不是很快。目前，机器人正常运作速度或许已经接近人类操作员的速度。机器人的每个主要运动通常需要大约1秒时间。对一个机器人来说,让它们将一块钢从输送机到装载进数控车床大约需要十个不同的动作，这个动作将耗费10秒。人类操作员能在同样的时间里完成相同的工作。生产力的增长是一致性的操作的结果。在工作期间人类操作员一遍一遍的重复同样的工作，他或她就会慢下来。机器人在程序化的速度下连续的工作,因此在工作日内能完成更多的零件。可以制造定制的自动化设备做与机器人同样的工作。这种定制的自动化设备可以在不到一半的时间里完成机器人或人们的装载工作。问题是设计并制造这种特殊的机器,它只能完成特定的或定制的工作。如果在工作中有任何改变，这台机器必须完全重建，或仪器必须报废并设计制造另一台新的机器。另一方面，机器人可以重新编程，并且在同一天就可以做新的工作。定制的自动化设备在工业中仍然有一定的作用。如果公司知道一份工作多年来不会改变，尽快的定制自动化机器仍然是一个不错的选择。在工厂中有其他的一些定制的自动化设备不能轻易的完成的工作。对于这些工作机器人可能是个不错的选择。其中一个例子就是喷漆，它是一项具有危险性的工作，因为从许多油漆散发出来烟雾都是有毒和易爆的。现在由机器人来做外壳喷漆的工作。机器人已经被“示教”进行喷涂由公司制造的不同大小的外壳尺寸。另外，机器人可以在喷漆室这种有毒的环境下工作，从而毋须考虑这种烟雾对工作在室内的人长期的影响。柔性自动化机器人有另一个优点:“他们在制造工厂可以做不同的工作”。如果机器人在最初购买是用于装卸冲床并且这个工作在产品设计上不再需要改变时,在工厂里机器人可以去做另一个工作。例如，它可以移到装配操作的末端来卸载从输送机运输来的已完成的附件，并放到货盘出货。准确性和重复性机器人的一个重要特征是能准确的完成其任务。当机器人编制程序程以执行特定的任务时，它被引导到确定特定的点并且编制程序来记录所在点的位置，程序编制完成后，机器人转向“运行”并执行程序。可惜的是,这个机器人不会走到所有程序设定点的准确位置，例如，机器人可能会产生与确切点0.025英寸的误差。机器人在第一次执行点的计划中，如果0.025英寸是最大误差，就说明该机器人的精度为0.025英寸。除了准确性，我们也关心机器人的可重复性。一个机器人的重复性是衡量其每次程序执行后返回到与其程序点之间的位置接近程度。举例来说,第一次执行程序时，机器人产生0.025英寸的误差，在接下来的执行计划中，机器人在到达这个点之前的循环会产生0.010英寸的误差。虽然机器人共有0.035英寸的误差。但从最初的编程点，其精度为0.025英寸，其重复性为0.010英寸。机器人的主要部件机器人的主要部件有机械手、电源、控制器。机械手用来抓取制造中所需要的资料，零件，或特殊工具。电源提供机械手运动的动力。控制器用来控制电源，使机械手完成其任务。机器人的轴运动机器人机械手的不同运动形式是由机器人的自由度数或轴来定义的。如果机器人的机械臂可以旋转，这个机器人可以称为是一个单轴机器人。如果机械手可以上下移动以及旋转，机器人可称为双轴机器人。如果除了旋转运动和上下运动，机械手也可以延长其手臂，或称为“延伸”，这个机器人可认为是一个三轴机器人(如图24.1)。大多数工业机器人都有三个主轴运动(旋转、上下、延伸)以及一些短轴运动。图24.1有两个线性轴和一个旋转轴运动的三轴机器手机器人的短轴存在于机器人的手腕，机器人的手腕与机器人手臂的末端连接。机器人手腕有三个可能的运动或轴：俯仰、翻转、偏转（如图24.2）。手腕上下弯曲是俯仰运动，手腕的转动是翻转运动，手腕的侧面运动偏转运动。图24.2机器人手腕的三个自由度长轴与短轴的结合给了机器人六种能完成的动作(六轴或六个自由度数)。许多工业机器人装配了所有的六轴，然而，其中有三个长轴，仅仅只有一个或两个短轴。机器人的分类机器人的手臂末端可以达到的总面积称为工作区间。根据其工作区间，机器人可以分为四类：圆柱坐标机器人、直角坐标机器人、球坐标机器人和关节坐标机器人。也可以按控制方式，将机器人分为三种运动形式：拾取和放置运动、点到点运动、连续轨迹运动,这些术语描述机械手在其工作区间的动作。 本文摘选自“机器人及自动化系统”，罗伯特L胡克斯特拉，CmfgE，华南西部出版公司，1986年。Robots Industrial robots became a reality in the early 1960s when Joseph Engelberger and George Devol teamed up to form a robotics company they called “Unimation. A robot is not simply another automated machine. Automation began during the industrial revolution with machines that performed jobs that formerly had been done by human workers. Such a machine, however, can do only the specific job for which it was designed, whereas a robot can perform a variety of jobs.A robot must have an arm. The arm must be able to duplicate the movements of a human worker in loading and unloading other automated machines, spraying paint, welding, and performing hundreds of other jobs that cannot be easily done with conventional automated machines.Definition of A RobotThe Robot Industries Association (RIA) has published a definition for robots in an attempt to clarify which machines are simply automated machines and which machines are truly robots. The RIA definition is as follows:A robot is a reprogrammable multifunctional manipulator designed to move material, parts, tools, or specialized devices through variable programmed motions for the performance of a variety of tasks. This definition, which is more extensive than the one in the RIA glossary at the end of this book, is an excellent definition of a robot. We will look at this definition, one phrase at a time, so as to understand which machines are in fact robots and which machines are little more than specialized automation.First, a robot is a “reprogrammable multifunctional manipulator.” In this phrase RIA tells us that a robot can be taught (reprogrammed) to do more than one fob by changing the information stored in its memory. A robot can be reprogrammed to load and unload machines, weld, and do many other jobs (multifunctional).A robot is a “manipulator”. A manipulator is arm (or hand) that can pick up or move things. At this point we know that a robot is an arm that can be taught to do different jobs.The definition goes on to say that a robot is designed to move material, parts, tools or Specialized devices material, includes wood, steel, plastic, cardboardanything that is used in the manufacture of a product.A robot can also handle parts that have been manufactured. For example, a robot can load a piece of steel into an automatic lathe and unload a finished part out of the lathe.In addition to handling material and parts, a robot can be fitted with tools such as grinders, buffers, screwdrivers, and welding torches to perform useful work. Robots can also be fitted with specialized instruments or devices to do special jobs in a manufacturing plant .Robots can be fitted with television cameras for inspection of parts or products. They can be fitted with lasers to accurately measure the size of parts being manufactured. The RIA definition closes with the phrase, through variable programmed motions for the performance of a variety of tasks.” This phrase emphasizes the fact that a robot can do many different jobs in a manufacturing plant .The variety of jobs that a robot can do is limited only by the creativity of the application engineer.Jobs for Robots Jobs performed by robots can be divided into two major categories: hazardous jobs and repetitive jobs.Hazardous Jobs Many applications of robots are in jobs that are hazardous to humans. Such jobs may be considered hazardous because of toxic fumes, the weight of the material being handled, the temperature of the material being handled, the danger of working near rotating or press machinery, or environments containing high levels of radiation.Repetitive Jobs In addition to taking over hazardous jobs，robots are well suited to doing extremely repetitive jobs that must be done in manufacturing plants .Many jobs in manufacturing plants require a person to act more like a machine than like a human. The job may be to pick a piece up from here and place it there. The same job is done hundreds of times each day. The job requires little or no judgment and little or no skill .This is not said as a criticism of the person who does the job, but is intended simply to point out that many of these jobs exist in industry and must be done to complete the manufacture of products. A robot can be played at such a work station and can perform the job admirably without complaining or experiencing the fatigue and boredom normally associated with such a job.Robot SpeedAlthough robots increase productivity in a manufacturing plant, they are not exceptionally fast. At present, robots normally operate at or near the speed of a human operator. Every major move of a robot normally takes approximately one second. For a robot to pick us a piece of steel from a conveyor and load it into a lathe may require ten different moves taking as much as ten seconds. A human operator can do the same job in the same amount of time. The increase in productivity is a result of the consistency of operation. As the human operator repeats the same job over and over during the workday, he or she begins to slow down. The robot continues to operate at its programmed speed and therefore completes more parts during the workday.Custom-built automated machines can be built to do the same jobs that robots do. An automated machine can do the same loading operation in less than half the time required by a robot or a human operator. The problem with designing a special machine is that such a machine can perform only the specific job, or which it was built. If any change is made in the job，the machine must he completely rebuilt, or the machine must be scrapped and a new machine designed and built .A robot, on the other hand, could be reprogrammed and could start doing the new job the same day.Custom-built automated machines still have their place in industry. If a company knows that a job will not change for many years, the faster custom-built machine is still a good choice.Other jobs in factories cannot be done easily with custom-built machinery. For these applications a robot may be a good choice .An example of such an application is spray painting. Spray painting is a hazardous job, because the fumes from many paints are both toxic and explosive. A robot is now doing the job of spraying paint on the enclosures. A robot has been taught to spray all the different sizes of enclosures that the company builds. In addition, the robot can operate in the toxic environment of the spray booth without any concern for the long-term effect the fumes might have on a person working in the booth.Flexible AutomationRobots have another advantage: they can be taught to do different jobs in the manufacturing plant. If a robot was originally purchased to load and unload a punch press and the job is no longer needed due to a change in product design，the robot can be moved to another job in the plant. For example, the robot could be moved to the end of the assembly operation and be used to unload the finished enclosures from a conveyor and load them onto a pallet for shipment.Accuracy and RepeatabilityOne very important characteristic of any robot is the accuracy with which it can perform its task. When the robot is programmed to perform a specific task, it is led to specific points and programmed to remember the locations of those points .After programming has been completed, the robot is switched to run and the program is executed. Unfortunately, the robot will not go to the exact location of any programmed point，For example，the robot may miss the exact point by 0.025 in. If 0.025 in. is the greatest error by which the robot misses any point during the first execution of the program，the robot is said to have an accuracy of 0.025 in. In addition to accuracy, we are also concerned with the robots repeatability. The repeatability of a robot is a measure of how closely it returns to its programmed points every time the program is executed. Say, for example, that the robot misses a programmed point by 0.025 in. the first time the program is executed and that, fluxing the next execution of the program, the robot misses the point it reached during the previous cycle by 0.010 in. Although the robot is a total of 0.035 in. from the original programmed point，its accuracy is 0 .025 in, and its repeatability is 0 .010 in.The Major Parts of a Robot The major parts of a robot are the manipulator, the power supply, and the controller. The manipulator is used to pick up material, parts, or special tools used in manufacturing. The power supply supplies the power to move the manipulator. The controller controls the power supply so that the manipulator can be taught to perform its task.Axes of Robot MovementThe various movements that the manipulator of a robot can make are defined by its degrees of freedom or axes. If a robots manipulator can rotate, the robot is said to be a single-axis robot .If the manipulator can move up and down as well as rotate, the robot is called a two-axis robot. If in addition to the rotational movement and the up-and-down movement，the manipulator can also extend its arm, or reach, the robot is said to be a three axis robot(Fig.24.1).Most industrial robots have all three major axes(rotational, up and down, and reach) as well as some minor axes of movement.Fig.24.1 Three-axis robot with cylindrical (post-type) manipulator, illustrating two linear axes, and one rotational axis, of movementThe minor axes of a robot are found in the robots wrist, The wrist of a robot is attached to the end of the robots arm. These are three possible movements or axes of a rolx3t wrist: pitch, roll and yaw (Fig.24.2).The pitch movement bends the wrist up and down .The roll movement is the twisting of the wrist. The yaw movement is the side-to-side movement of the wrist. Fig.24.2 The three possible movements or axes of a robot wristThe combination of the major axes and the minor axes gives the robot six possible movements ( six axes or six degrees of freedom ).Many industrial robots are equipped with all six axes robots, however, have the three major axes but only one or two of the minor axes. Classification of Robots The total area that the end of the robots: arm can reach is called the work envelope. T Robots can be classified according to their work envelopes into four types: the cylindrical coordinate robot, the rectangular coordinate robot, the spherical coordinate robot, and the jointed arm coordinate robot. They also can be classified by motion control .There are three major classifications of motion for robots: pick-and-place, point-to-point, and continuous path. These terms describe the movements the manipulator can make within its work envelope, Selected from “Robotics and Automated systems”, Robert L. Hoekstra, CmfgE, South-Western Publishing Co, 1986.教师评语教师签名：12本科毕业论文（设计）完成情况登记表姓 名性 别 学 号学 院专 业农业机械化及其自动化班 级论文（设计）题目履带式机器人结构设计论文（设计）完成提交时间论文（设计）取得主要成果及学生