機(jī)器人--外文文獻(xiàn)

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-攀枝花學(xué)院本科畢業(yè)設(shè)計(jì) 英文翻譯Panzhihua UniversityRoboticsThe Robotics ApplicationMany of the robots in use tody do jobs that are especially difficult for human worker. These are the types of jobs that require great strength or pose danger. For example, robots are particularly useful in the auto-manufacturing industry where parts of automobiles must be welded together. A welding tool used by a human worker weighs about 100 pounds or more and is difficult to handle. As mechanical supermen, robots may be called upon to do anything from moving heay components between workstations on a factory floor to carrying bags of cement.Spray painting is another task suited to robots because robots do not need to breathe. Unlike human painters, they are unaffected by the poisonous fumes. Robots are better at this task, not because they are faster or cheaper than humans, but because they work in a place where humans cannot.Third in the list of useful jobs for robots is the assembly of electronnic parts. Robots shine at installing chips in printed circuit boards because of a capability that robots have that people don’t . A robot, one properly programmed, will not put a chip in the wrong place. This automatic accuracy is particularly valuable in this kind of industry because locating and fixing mistakes is costly.Robotics RevolutionEarlier robots were usually blind and deaf, but newer types of robots are fitted with video cameras and other sensing devices that can detect heat, texture, size, and sound. These robots are used in space projects, nuclear stations, and underwater exporation research.Inther efforts to expand the range of robotic applications, reseachers are looking beyon traditional designs to examine a variety of potential models from the biological world. The industrial arm is a classic example. Scientists have been able to model robots to imitate the vertebrate spine of a snake in order to paint the interior of automobiles. They have simulated the muscle structure and movement of an elephant’s trunk in an attempt to create a robotic arm capable of lifting heavy objects. Scientists also emulate the flexibility of an octopus where the tentacles can conform to the fragile objects of any shape and hold them with uniform, gentle pressure. A variation of this design can be used to handle animals, turn hospital patients in their beds, or lift asmall child.The challenge of equipping robots with the skills to operate independently, outside of a factory or laboratory, has taxed theingenuity and creativity of academic, military, and industral scientists for years. Simply put, robot hands-like robot legs, or eyes, -攀枝花學(xué)院本科畢業(yè)設(shè)計(jì) 英文翻譯orreasoning powers-have long way to go before they can approach what biological evlution has achieved over by the course of hundreds of millions of years. Much more will have to happen in laboratories around the world before the robots can be compared to nature’s handiwork.In the meantime, the robotics revolution is already beginning to change the kind of work that people do. The boring and dangerous jobs are now assumed by robots. By the turn of the century, more and more humans will be required for tasks that machine can not do. There are slso some industrialists who hope that by the year 2000 all their empoyee will be knowledge workers, no longer standing on assembly lines but rather sitting at desks and computer terminals to deal with information. These changes are already under way, and their pace accelerates every year.Intelligent RobotsA new phase in robot applications has been opened with the development of “intelligent robots”. An intelligent robot is bascally one that must be capable of sensing its surrounding and possess intelligence enough to respond to a changing environment in much the same way as we do. Such ability requires the direct application of sensory perception and artificial intelligence. Much of reseach in robotics has been and is still concerned with how to equip robots with visual sensors-eyes and tactile sensors-the”fingers”. Artificial intelligence will enable the robot to changes in its task and in its environment, and to reason and make decisions in reactiong to those changes.Visional SensoryMuch effort has been made to simulate similar human sensory abilities for inelligent robots. Among them ,vision is the most important sense as it is estimated that up to 80% of sensory information is received by vision. Vision can be bestowed on robotic systems by using imaging sensors in various ways. For improving accuracy of performance, it can help precisely adjust the robot hand by means of optical feedback control using visual sensors. Determining the location, orientation, and recognition of the parts to be picked up is another important application.Among the vision system, one of the key components is imagery sensor. The imagery sensor of a robot system is defined as an electro-optical device that converts an optical image to a video signal. The image sensor is usually either a TV-camera or a solid state sensory device, for exanple, change-couple devices(CCD). The latter device offers greater sensitivity, long endurance and lightweight, and is thus welcome when compared with the TV-camera. The camera system contains not only the camera detector but also, and very importantly, alens system. The lens determines the field of view, the depth of focous, ans other optical factors that directly affect the quality of the image detected by the camera. Either TV-camera or CCDs produce an image by generating an analogue value on every pixel, proportional to its light intensity. To enable a digital computer to work with this signal, an analongue-to-digital(A/D) converter is needed to transfer analogue into digital data, then stored in random access menory(RAM), installed in computer. The computer analyzes the data and extracts such imagery information as edges, colors and -攀枝花學(xué)院本科畢業(yè)設(shè)計(jì) 英文翻譯textures of the objects in the image. Finally, the computer interprets or understands what the image represents in terms of knowledge about the scene and gives the robot a symbolic description of its environment.Tactile SensoryNext to vision in importance is tactile sensing or touching. Imagine the blind can do delicate jobs relying on his/her sensitive tactile. A blind robot can be extremely effective in performing an assembly task using only a sense of touch. Touch is of particular importance for providing feedback necessary to grip delicate objects firmly without causing damage to them.To simulate tactile in human hands, a complete tactile-sensing system must peform three fundmental sensing perations: (1)joint force sensing which senses the force applies to robot’s hand, wrist and arm joints; (2)touch sensing which sense the preeure applied to various points on the hand’s surface or the gripper’s surface; (3)slip sensing which senses any movement of the object while it is being graspeed.The joint forces are usually sensed using various strain gauges arranged in robotwrist assembly. A strain gauge is a force-sensing element whose resistance changes in proportion to the amount of the force applied to the element. The simplest application of touch sensor is gripper equipped with an array of miniature microswitches. This type of sensor can only determine the presence or absence of an object at a particular point or an array of points of the robot hand. A more advanced type of touch sensors uses arrays of pressure-sensitive piezoelectric material (conductive rubber or foam, etc.). The arrangement allows the sensor to perceive changes in force and pressure within the robothand. Since the force at each point can be determined, the force on its surface can be mapped and the shapes of objects grasped in the robot hand be determined respectively. Slip sensing is required for a robot to create the optimum amount of grasping force applied to a delicate, fragile object. This ability prevents damage to the object and allows the object to be picked up without the danger of being droped. The gripping force is increased step by step until the object has been firmly grasped and no more slip occurs.The integration of tactile sensing and vision sensing can dramatically enhance robotic assembly task. An example of this type of sensors would be a vision used to locate and identify objects and position of the robot itself, combined with a tactile sensor usedto detech the distribution of force and pressure, and determine torque, weight, center of mass and compliance of the material it handle. The hand-eye coordination for general- purpose manipulation will be extremely powerful in the industrial world.-攀枝花學(xué)院本科畢業(yè)設(shè)計(jì) 英文翻譯