機(jī)械手外文原文

1、Industrial RobotsModern 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 failu

2、res 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.A six-axis robot like the yellow one below costs about $60,000. What I find interesting is that deploying the robot c

3、osts another $200,000. Thus, the cost of the robot itself is just a fraction of the cost of the total system. The tools the robot uses combined with the cost of programming the robot form the major percentage of the cost. Thats why robots in the auto industry are rarely reprogrammed. If they are goi

4、ng to go to the expense of deploying a robot for another task, then they may as well use a new robot.This is pretty much the typical machine people think of when they think of industrial robots. Fanuc makes this particular robot. Fanuc is the largest maker of these type of robots in the world and th

5、ey are almost always yellow. This robot has six independent joints, also called six degrees of freedom. The reason for this is that arbitrarily placing a solid body in space requires six parameters; three to specify the location (x, y, z for example) and three to specify the orientation (roll, yaw,

6、pitch for example).If you look closely you will see two cylindrical pistons on the side of the robot. These cylinders contain anti-gravity springs that are a big part of the reason robots like these can carry such heavy loads. These springs counter-balance against gravity similar to the way the spri

7、ngs on the garage door make it much easier for a person to lift.You will see robots like these welding, painting and handling materials.The robot shown at right is made by an American company, Adept Technology. Adept is Americas largest robot company and the worlds leading producer of SCARA robots.

8、This is actually the most common industrial robot. SCARA stands for Selective Compliance Articulated (though some folks use Assembly here) Robot Arm. The robot has three joints in the horizontal plane that give it x-y positioning and orientation parallel to the plane. There is one linear joint that

9、supplies the z positioning. This is the typical pick and place robot. When combined with a vision system it can move product from conveyor belt to package at a very high rate of speed (think Lucy and the candies but way faster).The robots joint structure allows it to be compliant (or soft) to forces

10、 in the horizontal plane. This is important for peg in hole type applications where the robot will actually flex to make up for inaccuracies and allow very tight part fits.The machine at left can be called a Cartesian robot, though calling this machine a robot is really stretching the definition of

11、a robot. It is Cartesian because it allows x-y-z positioning. Three linear joints provide the three axes of motion and define the x, y and z planes. This robot is suited for pick and place applications where either there are no orientation requirements or the parts can be pre-oriented before the rob

12、ot picks them up (such as surface mounted circuit board assembly)The industrial robot is used in the manufacturing environment to increase productivity . It can be used to do routine and tedious assembly line jobs , or it can perform jobs that might be hazardous to do routine and tedious assembly li

13、ne jobs , or it can perform jobs that might be hazardous to the human worker . For example , one of the first industrial robots was used to replace the nuclear fuel rods in nuclear power plants . A human doing this job might be exposed to harmful amounts of radiation . The industrial robot can also

14、operate on the assembly line , putting together small components , such as placing electronic components on a printed circuit board . Thus , the human worker can be relieved of the routine operation of this tedious task . Robots can also be programmed to defuse bombs , to serve the handicapped , and

15、 to perform functions in numerous applications in our society .The robot can be thought of as a machine that will move an end-of-arm tool , sensor , and gripper to a preprogrammed location . When the robot arrives at this location , it will perform some sort of task . This task could be welding , se

16、aling , machine loading , machine unloading , or a host of assembly jobs. Generally , this work can be accomplished without the involvement of a human being , except for programming and for turning the system on and off .The basic terminology of robotic systems is introduced in the following : 1. A

17、robot is a reprogrammable , multifunctional manipulator designed to move parts , materials , tools , or special devices through variable programmed motions for the performance of a variety of different task . This basic definition leads to other definitions , presented in the following paragraphs ,

18、that give a complete picture of a robotic system 2. Preprogrammed locations are paths that the robot must follow to accomplish work . At some of these locations , the robot will stop and perform some operation , such as assembly of parts , spray painting , or welding . These preprogrammed locations

19、are stored in the robots memory and are recalled later for continuous operation . Furthermore , these preprogrammed locations , as well as other program data , can be changed later as the work requirements change . Thus , with regard to this programming feature , an industrial robot is very much lik

20、e a computer , where data can be stored and later recalled and edited .3. The manipulator is the arm of the robot . It allows the robot to bend , reach , and twist . This movement is provided by the manipulators axes , also called the degrees of freedom of the robot . A robot can have from 3 to 16 a

21、xes . The term degrees of freedom of freedom will always relate to the number of axes found on a robot .4. The tooling and grippers are not part of the robotic system itself ; rather , they are attachments that fit on the end of the robots arm . These attachments connected to the end of the robots a

22、rm allow the robot to lift parts , spot-weld , paint , arc-weld , drill , deburr , and do a variety of tasks , depending on what is required of the robot .5. The robotic system can also control the work cell of the operating robot . the work cell of the robot is the total environment in which the ro

23、bot must perform its task . Included within this cell may be the controller , the robot manipulator , a work table , safety features , or a conveyor . All the equipment that is required in order for the robot to do its job is included in the work cell . In addition , signals from outside devices can

24、 communicate with the robot in order to tell the robot when it should assemble parts , pick up parts , or unload parts to a conveyor .The robotic system has three basic components : the manipulator , the controller , and the power source .A . Manipulator The manipulator , which does the physical wor

25、k of the robotic system , consists of two sections : the mechanical section and the attached appendage . The manipulator also has a base to which the appendages are attached . Fig.1 illustrates the connection of the base and the appendage of a robot .The base of the manipulator is usually fixed to t

26、he floor of the work area .Sometimes , though , the base may be movable . In this case , the base is attached to either a rail or a track , allowing the manipulator to be moved from one location to another .As mentioned previously , the appendage extends from the base of the robot . The appendage is

27、 the arm of the robot . It can be either a straight , movable arm or a jointed arm . the jointed arm is also known as an articulated arm .The appendages of the robot manipulator give the manipulator its various axes of motion . These axes are attached to a fixed base , which , in turn , is secured t

28、o a mounting . This mounting ensures that the manipulator will remain in one location。At the end of the arm , a wrist is connected . The wrist is made up of additional axes and a wrist flange . The wrist flange allows the robot user to connect different tooling to the wrist for different jobs . The

29、manipulators axes allow it to perform work within a certain area . This area is called the work cell of the robot , and its size corresponds to the size of the manipulator . Fig.2 illustrates the work cell of a typical assembly robot . As the robots physical size increases , the size of the work cel

30、l must also increase .The movement of the manipulator is controlled by actuators , or drive systems . The actuators , or drive system , allows the various axes to move within the work cell . The drive system can use electric , hydraulic , or pneumatic power . The energy developed by the drive system

31、 is converted to mechanical power by various mechanical drive systems .The drive systems are coupled through mechanical linkages .These linkages, in turn , drive the different axes of the robot . The mechanical linkages may be composed of chains , gears ,and ball screws.B. ControllerThe controller i

32、n the robotic system is the heart of the operation. The controller stores preprogrammed information for later recall, control peripheral devices, and communicates with computers within the plant for constant updates in production The controllers is used to control the robot manipulators movements as

33、 well as to control peripheral components within the work cell. The user can program the movements of the manipulator into the controller through the use of a hand-held teach pendent. This information is stored in the memory of the controller for later recall. The controller stores all program data

34、of the robotic system. It can store several different programs, and any of these programs can be edited.The controller is also required to communicate with peripheral equipment within the work cell. For example, the controller has an input line that identifies when a machining operation is completed

35、. When the machine cycle is completed, the input line turns on, telling the controller to position the manipulator so that it can pick up the finished part. Then, a new part is picked up by the manipulator and placed into the machine. Next, the controller signals the machine to start operation.The c

36、ontroller can be made from mechanically operated drums that step through a sequence of events. This type of controller operates with a very simple robotic system. The controllers found on the majority of robotic systems are more complex devices and represent state-of-the-art electronics. That is, th

37、ey are microprocessor-operated. These microprocessors are either 8-bit, 16-bit, or 32-bit processors. This power allows the controller to be very flexible in its operation.The controller can send electric signals over communication lines that allow it to talk with the various axes of manipulator. Th

38、is two-way communication between the robot manipulator and the controller maintains a constant update of the location and the operation of the system. The controller also controls any tooling placed on the end of the robots wrist. The controller also has the job of communicating with the different plant computers . The communication link establishes