Read the text carefully and answer these question.
1) How do robots work?
2) How many categories can the application of robots be divided into? What are they?
3) What are practical achievements in the field of automated machines?
4) What problems do remain in robot development? How could they be solved?
The inspiration for the design of a robot manipulator is the human arm, but with some differences. For example, a robot arm can extend by telescoping – that is, by sliding cylindrical sections one over another to lengthen the arm. Robot arms also can be constructed so that they bend like an elephant trunk. Grippers, or end effectors, are designed to mimic the function and structure of the human hand. Many robots are equipped with special purpose grippers to grasp particular devices such as a rack of test tubes or an arc-welder.
The joints of a robotic arm are usually driven by electric motors. In most robots, the gripper is moved from one position to another, changing its orientation. A computer calculates the joint angles needed to move the gripper to the desired position in a process known as inverse kinematics.
Some multijointed arms are equipped with servo, or feedback, controllers that receive input from a computer. Each joint in the arm has a device to measure its angle and send that value to the controller. If the actual angle of the arm does not equal the computed angle for the desired position, the servo controller moves the joint until the arm's angle matches the computed angle. Controllers and associated computers also must process sensor information collected from cameras that locate objects to be grasped, or they must touch sensors on grippers that regulate the grasping force.
Any robot designed to move in an unstructured or unknown environment will require multiple sensors and controls, such as ultrasonic or infrared sensors, to avoid obstacles. Robots, such as the National Aeronautics and Space Administration (NASA) planetary rovers, require a multitude of sensors and powerful onboard computers to process the complex information that allows them mobility. This is particularly true for robots designed to work in close proximity with human beings, such as robots that assist persons with disabilities and robots that deliver meals in a hospital. Safety must be integral to the design of human service robots.
Today most robots are used in manufacturing operations; the applications can be divided into three categories: (1) material handling, (2) processing operations, and (3) assembly and inspection.
Material-handling applications include material transfer and machine loading and unloading. Material-transfer applications require the robot to move materials or work parts from one location to another. Many of these tasks are relatively simple, requiring robots to pick up parts from one conveyor and place them on another. Other transfer operations are more complex, such as placing parts onto pallets in an arrangement that must be calculated by the robot. Machine loading and unloading operations utilize a robot to load and unload parts at a production machine. This requires the robot to be equipped with a gripper that can grasp parts. Usually the gripper must be designed specifically for the particular part geometry.
In robotic processing operations, the robot manipulates a tool to perform a process on the work part. Examples of such applications include spot welding, continuous arc welding, and spray painting. Spot welding of automobile bodies is one of the most common applications of industrial robots in the United States. The robot positions a spot welder against the automobile panels and frames to complete the assembly of the basic car body. Arc welding is a continuous process in which the robot moves the welding rod along the seam to be welded. Spray painting involves the manipulation of a spray-painting gun over the surface of the object to be coated. Other operations in this category include grinding, polishing, and routing, in which a rotating spindle serves as the robot's tool.
The third application area of industrial robots is assembly and inspection. The use of robots in assembly is expected to increase because of the high cost of manual labour common in these operations. Since robots are programmable, one strategy in assembly work is to produce multiple product styles in batches, reprogramming the robots between batches. An alternative strategy is to produce a mixture of different product styles in the same assembly cell, requiring each robot in the cell to identify the product style as it arrives and then execute the appropriate task for that unit.
The design of the product is an important aspect of robotic assembly. Assembly methods that are satisfactory for humans are not necessarily suitable for robots. Using a screw and nut as a fastening method, for example, is easily performed in manual assembly, but the same operation is extremely difficult for a one-armed robot. Designs in which the components are to be added from the same direction using snap fits and other one-step fastening procedures enable the work to be accomplished much more easily by automated and robotic assembly methods.
Inspection is another area of factory operations in which the utilization of robots is growing. In a typical inspection job, the robot positions a sensor with respect to the work part and determines whether the part is consistent with the quality specifications.
In nearly all industrial robotic applications, the robot provides a substitute for human labour. There are certain characteristics of industrial jobs performed by humans that identify the work as a potential application for robots: (1) the operation is repetitive, involving the same basic work motions every cycle; (2) the operation is hazardous or uncomfortable for the human worker (e.g., spray painting, spot welding, arc welding, and certain machine loading and unloading tasks); (3) the task requires a work part or tool that is heavy and awkward to handle; and (4) the operation allows the robot to be used on two or three shifts.
Many robot applications are for tasks that are either dangerous or unpleasant for human beings. In medical laboratories, robots handle potentially hazardous materials, such as blood or urine samples. Robots are being used to assist surgeons in installing artificial hips, and very high-precision robots can assist surgeons with delicate operations on the human eye. Research in telesurgery uses robots, under the remote control of expert surgeons that may one day perform operations in distant battlefields.
In other cases, robots are used in repetitive, monotonous tasks in which human performance might degrade over time. Robots can perform these repetitive, high-precision operations 24 hours a day without fatigue. A major user of robots is the automobile industry. General Motors Corporation uses approximately 16,000 robots for tasks such as spot welding, painting, machine loading, parts transfer, and assembly. Assembly is one of the fastest growing industrial applications of robotics. It requires higher precision than welding or painting and depends on low-cost sensor systems and powerful inexpensive computers. Robots are used in electronic assembly where they mount microchips on circuit boards.
Activities in environments that pose great danger to humans, such as locating sunken ships, cleanup of nuclear waste, prospecting for underwater mineral deposits, and active volcano exploration, are ideally suited to robots. Similarly, robots can explore distant planets. NASA's Galileo, an unpiloted space probe, traveled to Jupiter in 1996 and performed tasks such as determining the chemical content of the Jovian atmosphere.
Robotic manipulators create manufactured products that are of higher quality and lower cost. But robots can cause the loss of unskilled jobs, particularly on assembly lines in factories. New jobs are created in software and sensor development, in robot installation and maintenance, and in the conversion of old factories and the design of new ones. These new jobs, however, require higher levels of skill and training. Technologically oriented societies must face the task of retraining workers who lose jobs to automation, providing them with new skills so that they can be employable in the industries of the 21st century.
Automated machines will increasingly assist humans in the manufacture of new products, the maintenance of the world's infrastructure, and the care of homes and businesses. Robots will be able to make new highways, construct steel frameworks of buildings, clean underground pipelines, and mow lawns. Prototypes of systems to perform all of these tasks already exist.
One important trend is the development of microelectromechanical systems, ranging in size from centimeters to millimeters. These tiny robots may be used to move through blood vessels to deliver medicine or clean arterial blockages. They also may work inside large machines to diagnose impending mechanical problems.
Perhaps the most dramatic changes in future robots will arise from their increasing ability to reason. The field of artificial intelligence is moving rapidly from university laboratories to practical application in industry, and machines are being developed that can perform cognitive tasks, such as strategic planning and learning from experience. Increasingly, diagnosis of failures in aircraft or satellites, the management of a battlefield, or the control of a large factory will be performed by intelligent computers.
Work in pairs or small groups. Read the text again and say whether the author is optimistic or sceptical about modern robots. Find the facts to prove your idea, then report the general idea of the group to the class.
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