2022年2022年工业机器人概论 .pdf

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1、Smart Robot (1) How Robots Work There are three main parts of a typical industrial robot: the controller, the manipulator, and the end-effector (see Figure 1). The controller consists of the hardware and software usually involving a microcomputer or micro-electronic components which guide the motion

2、s of the robot and through which the operator programs the machine. The manipulator consists of a base, usually bolted to the floor, an actuation mechanism the electric, hydraulic, or pneumatic apparatus that moves the armand the arm itself, which can be configured in various ways to move through pa

3、rticular patterns. In the arm, “ degrees of freedom ” basically, the number of different jointsdetermine the robot dexterity, as well as its complexity and cost. Finally, the end-effector, usually not sold as part of the robot, is the gripper, weld gun, spray painting nozzle, or other tool used by t

4、he robot to perform its task. The structure, size, and complexity of the robots varies, depending on the application and the industrial environment. Robots designed to carry lighter loads tend to be smaller and are operated electrically; many heavier units move their manipulator hydraulically. Some

5、of the simpler units are pneumatic. Some of the heaviest material-handling robots and the newer light-assembly robots are support. A few robots are mobile to a limited degree, they may, for instance, roll along fixed tracks in the floor or in their gantry supports. Similarly, there is a great variet

6、y of end-effectors, particularly grippers, most of which are customized for particular applications. Grippers are available to lift several objects at once, or to grasp a fragile object without damaging it. Programming.There are essentially two methods of programming a robot. The most commonly used

7、method is “ teaching by guiding. ” The worker either physically guides the robot through its path or uses switches on a control panel to move the arm. The controller records that path as it is “ taught ” . This process is rather slow and ties up valuable production equipment for programming. 名师资料总结

8、- - -精品资料欢迎下载 - - - - - - - - - - - - - - - - - - 名师精心整理 - - - - - - - 第 1 页，共 4 页 - - - - - - - - - Now beginning to emerge is “ offline programming ” , where an operator writes a program in computer language at a computer terminal and directs the robot to follow the written instruction. Each metho

9、d of programming has advantages that depend on the application. Teaching by guiding is the simplest and is actually superior for certain operations; in spray painting, for example, it is useful to have the operator guide the robot arm through its path because of the continuous, curved motions usuall

10、y necessary for even paint coverage. However, teaching by guiding offers minimal ability to “ edit” a path that is, to modify a portion of the path without recording the entire path. Off-line programming is useful for several reasons: 1) production need not be stopped while the robot is being progra

11、mmed; 2) the factory floor may be an inhospitable environment for programming, and off-line programming can be done at a computer terminal in an office; 3) as mechatronic technologies become more advanced and integrated, they will increasingly be able to generate robot programs automatically from de

12、sign and manufacturing data bases; and 4) an off-line written program can better accommodate more complex tasks, especially those in which “ branching ” is involved (e.g. , “ if the part is not present, then wait for the next cycle” ). These branching decisions require some kind of mechanism by whic

13、h the robot devices are unable to sense their external environment. The vast majority of robotic devices are unable to sense their environment, although they may have internal sensors to provide feedback to their controller on the position of the arm joints. Sensors. Devices for sensing the external

14、 environment, while often used in conjunction with robots, are a growing technology in themselves. The simplest sensors answer the question, “ Is something there or not?” For example, a light detector mounted beside a conveyor belt can signal when a part has arrived because the part breaks a light b

15、eam. Somewhat more complex are proximity sensors which, by bouncing sound off objects, can estimate how far away they are. The technology for these devices is fairly well established. The most 名师资料总结 - - -精品资料欢迎下载 - - - - - - - - - - - - - - - - - - 名师精心整理 - - - - - - - 第 2 页，共 4 页 - - - - - - - - -

16、 powerful sensors, however, are those that can interpret visual or tactile information; these have just begun to be practical. Ideally, vision sensors would allow a robot system to respond to changes in its environment and to inspect products as well as or better than a human could. However, using c

17、omputers to process images from a video camera has proven to be a difficult programming task. Routine variations in lighting, the complexity of the everyday environment, common variations in shape or texture, and the difference between a two-dimensional camera image and a three-dimensional world all

18、 complicate the task of computer processing of a video image. Other kinds of sensing devices, from proximity sensors to touch and force sensors, have received much less attention than machine vision, but they also play an important role in the factory environment, especially in assembly applications

19、. Robot System Elements The industrial robot consists of the following major subsystems: A manipulator- the mechanical arm mechanism consisting of a series of links and joints which accomplish the motion of an object through space. Closely resembling a human arm and hand, it consists of a base, shou

20、lder, elbow, and wrist; An end effector- a gripper or tool which will perform the robots intended task; An actuator drive system-providing electric, hydraulic or pneumatic energy to the manipulator and the end effector; A control unit or computer to provide the logical direction for the robot. Manip

21、ulator Mechanisms Four parameters define the end point specifications or limits for a manipulator: Coordinate reference system of motion Range or reach of the robot Actuation source, i.e., how powered Capacity or weight limitation The work space in which a robot is effective is a direct function of

22、that volume 名师资料总结 - - -精品资料欢迎下载 - - - - - - - - - - - - - - - - - - 名师精心整理 - - - - - - - 第 3 页，共 4 页 - - - - - - - - - within which the robot wrist assembly can be operated to deliver a tool, or other functional device (Figure 2). Coordinate reference system. Robots can be classified according to t

23、he spatial reference system defining their three axes of motion (x,y,z). These three will produce vertical, horizontal, and in-out motion about the robot center of motion, normally its fixed base. There are presently four basic geometric configurations in use for robot motion, each of which offers m

24、ore or less freedom of activity, with a corresponding cost dependency, the more agile being the more costly. The job will determine the choice most suitable for use. Rectangular or Cartesian motion-moving in the classical up-down, left-right, in-out directions. The wrist can be controlled in height,

25、 width and depth of operation with a great degree of accuracy. Cylindrical or rotational motion-An extendable arm moves up and down as well as in and out from a central pole, and swivels angularly around the pole. Polar or spherical motion-An extended arm mounted on a central pivot, reaches above an

26、d below its pivot point and rotates angularly around the pivot. Revolute or jointed arm motion-Human-like arm can bend and swivel at the shoulder and bend at the elbow. This motion allows the arm to move back close to the base, extending the work area of the robot. 名师资料总结 - - -精品资料欢迎下载 - - - - - - - - - - - - - - - - - - 名师精心整理 - - - - - - - 第 4 页，共 4 页 - - - - - - - - -