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Robots
WHAT IS A ROBOT The term robot comes from the Czechoslovakian wordfor "forced labor," invented by Karel Capek. Karel Capek used robots in his plays and had them look and behave like people. Today, the word "robot" is harder to define because of new designs and technology. The third edition of Websters's New International Dictionary defines a robot as "a machine in the form of a human being that performs the mechanical functions of a human being." However, today's robot makers are not interested in giving their creations human forms. Most industrial robots look like lobsters or oversized grasshoppers. Around 1981, the members of the Robot Institute of America, held a meeting to develop a definition of an industrial robot. Finally after long debate, they came up with the definition: "A reprogrammable, multifunctional manipulator designed to move material, parts, tools or specialized devices, through variable programmable motions, for the performance of a variety of tasks." The key wor ds in their definition are "reprogrammable" and "multifunctional." By "reprogrammable" they mean that if a robot gets a new assignment, it will need new instructions, but its basic structure will not change (except maybe a new mechanical hand). By "multifunctional" they mean a robot is the mechanical counter part of a computer that can handle various problems without any major hardware modifications. The only thing that changes when a robot is reassigned is its program of instructions. In modern robots, programmable microprocessors control all the robot's movements and actions. Robots can be taught by using a teaching mode. An operator moves the robot's hand through all of the desired motions manually with his own hand. When the robot is activated, it will repeat those same motions over and over again. Most robots are equipped with one hand and one arm of several articulated joints. Some of these joints swivel in smooth arcs mimicking the behavior of the human shoulder, wrist, and elbow. Other robots move in straight lines similar to a crane. Robots rarely have a pair of arms, and are usually stationary. If a robot moves that is all it does. Examples are delivery robots rolling down halls delivering mail or supplies. The hands and arms of early robots were pneumatically powered (air pressure) or hydraulically powered (fluid pressure). Flexible tubes carried the pressurized substances to the joints. Now, electric motors located at the joint give the robot greater precision and control, but slow down its movements. All robot manufacturers dream of joints with human-like tendons. Most robots are blind and are insensitive to their surroundings. Some have sensors triggered by light, pressure, or heat that can create a crude picture of what is happening. ROBOTIC ARMS There are four types of robot arms that are used today. Degrees of freedom are the axes around the arm in which it is free to move. The area a robot arm can reach is its work envelope. Rectangular arms are sometimes called "Cartesian" because the arm's axes can be described by using the X, Y, and Z coordinate system developed by Descartes. Descartes is a famous French philosopher, scientist, and mathematician. If a pen were attached to the arm, it would draw a rectangle which would be its work envelope. Imagine a graph where X would be side to side, and Y would be in and out on the graph. Up and down would be Z which runs through the graph and describes depth. Z also adds the third dimension. A cylindrical arm also has three degrees of freedom, but it moves linearly only along the Y and Z axes. Its third degree of freedom is the rotation at its base around the two axes. The work envelope is in the shape of a cylinder. The spherical arm replaces up and down movements along the two axes with a rocking motion of the arm. The spherical arm's work envelope is a partial sphere which has various length radii. The last and most used design is the jointed-arm. The arm has a trunk, shoulder, upper arm, forearm, and wrist. All joints on the arm can rotate, creating six degrees of freedom. Three are the X, Y, and Z axes. The other three are pitch, yaw, and roll. Pitch is when you move your wrist up and down. Yaw is when you move your hand left and right. Rotate your entire forearm as if you are drilling a hole. Your arm would rotate around an axis that goes through the center of your wristbone. This motion is called roll. What a robot does is stated in its program. The program tells a microprocessor what to do. The microprocessor sends signals to joint boards, which in turn, send signals to a motor. Then the motor moves the joint the way the program wants it to. Robots can be programmed by a computer. An operator enters the work movements into a computer which tells the robot what to do. Robots can also be "taught" what to do by having its arm moved. The operator moves the robot's arm with his own arm through all the movements. The robot preforms the movements over and over again. ROBOTS IN INDUSTRY In factories today, industrial robots perform such tasks as welding, machine loading and unloading, material handling, spray finishing, assembly, and machine applications. In nuclear power plants and other facilities where radiation is hazardous to humans, robotic arms that are partly machine and human controlled are used for maintenance, repair, and waste removal. Similar arms on diving vehicles facilitate undersea salvage and exploration by navies and offshore oil industry. WELDING Industrial robots can perform two kinds of welding operations - spot and arc welding. For spot welding, two metal sheets are welded by laying one sheet on top of the other and fusing them with an electric gun at several points. This is a difficult and unpleasant task for humans because the welding gun is heavy. Also, assembly lines only allow a short time to move the gun, and welds can be placed inconsistently or missed. The parts move on a conveyor belt and as they pass by, the robot welds them. The robots remember the position of each weld that is to be made, and can recall other programs when a new material appears on the line. In arc welding, metal sheets are pressed together. Then a thin tungsten wire at the tip of and electrode is brought close to the surface. Current is passed through the electrode, creating a spark. The resulting heat, as much as 6,500 degrees Fahrenheit, melts the sheets together. Robots are used instead of humans because of the heat and flying sparks. Also, the robot must hold the electrode at the same height while welding. This is hard for a human to do hour after hour. MATERIAL HANDLING Material handling is the second largest industrial robot application. A common material handling task is palletizing parts as they come off a conveyor or depalletizing parts in order to put them on a conveyor. Pallets are platforms on which items are transported or stored. The robot must know if a pallet is filled, half-filled, or empty. Manufacturers use a bar code like the ones in supermarkets to tell the robot about the pallet. Also, some robots have two- dimensional vision that can recognize the pallet. The program tells the robot to place the parts in different positions. In depalletizing, the program tells the robot where to reach for and object and how to grab it with the correct force. Robots are now used in Hackettstown, New Jersey. They are used to pack M&M's and then weigh the package to see if the right amount has been packaged. The robots the place the packages in a box. MACHINE LOADING AND UNLOADING Machine loading and unloading robots pick up and transfer parts to and from machines. The die-casting industry uses robots to remove parts from die-casting machines. The die-casting process forms parts by pouring molten metals in molds which are cooled later. The working environment is unpleasant for humans because of the heat. Preparing molds is tiring and boring because the steps are repeated over and over again. Robots are well suited for this work. SPRAY FINISHING Spray finishing includes the application of paint, enamel, polyurethane, and other protective materials. Human workers must hold the gun a certain distance and angle from the surface. Also, he must move the gun continuously to prevent dripping. The painter uses his own judgements regarding a good finish. Because of this, products are never identically finished. The spray finishing environment is one of the most noxious for humans to work in. Fumes from solvents are toxic and sometimes carcinogenic. There is a hazard of fire since finishes are flammable, and noise from air discharge can damage hearing. In the automotive industry, robots are use to paint cars, but cannot paint all of it. Operators must finish the job after the robots have done what they can. The risk of fire demands the hydraulic robots rather than the electric driven robots. Since robots move more smoothly than humans, the paint coat will be more consistent. Also, robots can be programmed to switch colors. Spray finishing robots cut costs because they require less light, reduce fresh-air requirements, reduce exhaust, and lesson energy costs. Since robots can operated in isolated areas, fewer particles stick to coated surfaces as they dry. The isolated environment also means no ventilation or noise elimination is necessary. ASSEMBLY AND INSPECTION Robots can bolt or screw pieces together depending on the job needed. The assembly lines move fast, so robots are well suited for the job. The robots move fast and take only one or two seconds to fit pieces together. Inspection robots fit pieces into a mold to see if they fit correctly. If the piece doesn't fit the robot rejects or signals a warning. Robots can rotate pieces to see if they fit and can change angles. Some advanced robots scan the pieces as they go by on a conveyor belt. The robot then checks the piece's measurements to the correct measurements. This technique is very fast and usually accurate. Humans aren't really interested in this job. Humans would take longer to fit the pieces into the mold because they are not sure which way to turn the piece. Also, humans can't scan pieces and check the measurements as they go by. ROBOTS IN HAZARDOUS ENVIRONMENTS Master or slave manipulators are robotic arms that humans can control with joy sticks as well as computers. They are use in hazardous land, sea, and space environments. The nuclear industry handles radioactive fuel and wastes with these devices. The mining industry uses them for waster disposal. Sea salvage operations would be impossible to be carried out without these arms. Even the Space Shuttle use an arm that helps the astronauts launch satellites. Three robotic manipulators are used to maintain the linear accelerator, or "atom smasher", at the Los Alamos Meson Physic Facility in New Mexico. When protons are accelerated, strong radioactivity occurs. Even if the machine is off, radiation is still high and hazardous to humans. Workers use the manipulators to maintain the target area. The arms hang over the area from a large hydraulic system. The operators, which are sitting behind a protective wall, move the controller which moves the arm. The arm has bilateral force sensing which allows the arm to have collisions with objects, and yet continue to work. The arm absorbs the shock the same way a human hand does when catching a ball. With these manipulators, workers can do almost all of the things people can do but without risking the effects of radiation. Soldering, electrical wiring, welding, and handling materials are some of the tasks achieved. In deep-sea activities, the hazard is not the object being retrieved, but depth itself. Humans can withstand depths up to 300 feet. Depths after that can be dangerous and unsafe because of pressure. A device called a "wasp" was developed and tested. It is a cross between a diving suit and a submarine with two robotic arms. The pilot in the suit can walk on the floor at depths up to 2,000 feet. The diver can look out the plexiglass dome, and move the arms with a joy stick. The wasp has been used to make many undersea discoveries. Now, several companies have been making and developing remotely operated vehicles (ROVs). One called the Scorpio can dive to a depth of 3,000 feet. It is tethered to a vehicle on the surface where it is controlled from, but it does not need a human inside. Scorpio's two arms can lift up to 250 pounds water weight. Several multimillion dollar projects are underway to improve ROVs so they can dive to depths of 6,000 feet. They are needed to salvage costly equipment, and offshore oil industry hopes to use them to maintain rigs. ROBOTS OF THE FUTURE Robotics and robot technology is advancing quickly. There are many dreams to have a robot do something or everything for you. Here are some ideas that we might see in the future. Many people are working on robotic defense systems that can protect the United States from destruction. Here is one idea: To protect the Unites States from nuclear missile attack, hundreds of nuclear battle stations would be put in orbit. When the station detects a missile launch, it move a hollow tube towards the missile. Then the station launches a laser beam that hits the missile before it reenters the atmosphere. To help astronauts retrieve satellites from space, a remote manipulator operated from inside the ship can be used. The manipulator would get to the satellite by using four small thrusters. When it reached the satellite, it would use a grappling device to tow the satellite back to the ship. The idea of having the manipulator repair the satellite by itself and return to ship arose from t

 



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