Technology Interactions p. 326-346
A duck runs quacking across the floor, flapping its wings, and spreading its feathers. Finally it dives into a pond. The duck gently eats the pieces of grain from the man's hand. Not so remarkable is it? You need a little more information. The duck is a mechanical device made from metal. Still not so remarkable? The duck was made by a French inventor named Jacques de Vaucanson in the 1700's. That's pretty remarkable!
We think of robots as marvels of modern technology. However, the idea of machines designed to imitate human actions existed over 3,000 years. The ancient Egyptians made puppets on strings.
How Robotics Developed
The duck you just read about was a crude robot. A robot is a machine made to act like a living thing. Robotics is the study of robots. Robotics is a control system technology. Through input data and a variety of processes, people have learned to control the output of machines. Today, robots are designed to do many of the tasks that humans used to do.
Ancient attempts at robotics were not control system technologies. Crude robots could not react to changing conditions as modern robots can. Many technological events had to take place before true robotics could develop. Designers and engineers had to learn how to transfer forces. They did this through gears and levers. The development of punch cards, computers, and automation was also important.
Robots are used today in a variety of ways. For example, during some joint replacement operations in humans, a hole must be drilled into the bone to accept the artificial joint. The accuracy of this hole is critical. Some surgeons now use robotic systems to position the drill and make the actual hole. The accuracy and steadiness of the robotic arm are hard to beat.
Mobile robots can crawl into the most unusual places. The Mermaid is an underwater robot that searches the sea bottom for unexploded mines. It can hold onto the sea floor in the roughest current. When the robot locates the mine, it self-destructs by blowing itself up. This detonates the mine.
Walking robots are capable of moving over rough ground and even up stairs. Police departments in large cities use walking robots to retrieve explosives from buildings.
Deep beneath the dark Atlantic Ocean robotic divers searched for the sunken ocean liner Titanic. The cameras and sonar on board the robotic diver sent signals to the computer on the mother ship. Suddenly, observers could see the hull of the great ship resting on the floor of the ocean.
During the 18th and 19th centuries, mechanical robots were built for entertainment purposes. These robots used springs, gears , levers, and pulleys to perform many tasks. These robots were called automatons. Some of them could play musical instruments, write letters with pen and ink, and even perform magic tricks.
In the early 1800's, Joseph-Marie Jacquard, a French weaver, invented a punch card system. He used it in his factory to produce fabric patterns. Holes were punched in stiff paper cards. These holes corresponded to patterns woven in fabric. Some rods were pushed through the openings in the cards. Other rods were held back. This arrangement of rods represented the color and pattern threads that the machine had to weave. The punch card process laid the foundation for modern computers.
Punch Cards and Computers
Herman Hollerith invented the punch card tabulating machine. The machine was used to tally data (information) during the 1890 United States census. Data was punched into a card. The machine inserted rod through the holes in the card. The rods then made contact in small cups of mercury, completing an electrical circuit. The electrical connection then made the hands on a dial move one space. In this way data was recorded and added.
Hollerith had created an electrical scanner and sensor. This technology was essential to later developments in computer control technology. Hollerith's company later joined other companies to form IBM.
The first computers were built during the 1940's. They were huge calculating machines that took up an entire room. In 1948, a team of scientists invented the transistor. This reduced the size of the computer. It also multiplied the speed at which the computer could make calculations.
Automation is a technique that is used to make a process automatic. The word was first used in the 1940's. It described work that had been done by people that was now being done by machines.
Automated factories used machine tools that were now being computer controlled. The most accurate machines at the time were numerical control machines. The system used numbers to describe the shape of a part and the tool's movement through the material. A punched paper roll (punched tape) had these movements recorded on it. This roll was fed through the computer. The machine tool would then automatically cut, grind, or drill the part to shape. (show Carvin automation here)
MODERN ROBOTIC SYSTEMS
Machine tools are not robots. Robots are more accurate. They are also more flexible and can make decisions. The word robot was first used in 1922 by Karel Capek, a Czechoslovokian writer. He wrote a play about mechanical humans, or robots. They worked in factories, where they replaced human workers. The Czech word robota means "slave labor." In Capek's play, the robots finally rebel against their masters-and take over the world!
Robots represent great power in today's workforce. By the 1970's, Japan had over 7,000 robots in automobile factories. These robots moved materials and parts. They welded, assembled, and painted automobiles on the assembly line. Robotic systems are designed to have humanlike movements. In many ways, robotic systems model human systems. Just as your brain sends commands to your arms and legs, a computer sends instructions to a robot. Computers are the brains of modern robotic systems. They control the movement of mechanical robotic arms.
There are sixteen joints in the human arm, wrist, and fingers. These joints provide us with forty degrees of freedom. a degree of freedom is the ability of the robot to move in a direction. Movement in a combination of joints allows human, as well as robotic, arms to move in any direction. The flexibility of these joints allows robots to handle a variety of materials in a variety of shapes. This flexibility gives robotic arms, or manipulators, the ability to move in any direction and grasp a variety of items.
Human hands are very flexible. They can grip almost any object in a variety of positions. Robotic hands have a much more difficult time. Often a variety of robotic hands must be used as an assigned task changes. Robotic hands, known as end effectors, can be quickly attached to a robotic wrist as a task may change.
The Work Envelope
The place where two moving parts of a robot are connected is called a joint, or axis. An arm robot (see above picture) called a manipulator moves at its waist (on base), shoulder, elbow, and wrist joints. Each degree of freedom in a robotic arm is provided by combining the movements of these joints. The space that a robotic arm moves within is called its work envelope. The design, or architecture, of the robotic arm will determine the size and shape of its working envelope.
POWER FOR ROBOTIC MOVEMENTS
Each moving robotic arm can be powered in a variety of ways. The selection of a power source depends upon what the robotic arm has to do. An electric motor known as a stepper motor is commonly used as an actuator, or power source, for robotic movements. One complete rotation of a stepper motor can be divided into hundreds of individual steps. Each step represents a fraction of a degree of movement. A stepper motor can rotate a small amount or a step each time an electrical signal is sent to it. Waist, shoulder, elbow, and wrist joints may each be powered by separate motors. The motor shaft transmits the Mechanical Energy through gears, shafts, and pulleys to the robotic joint. Robot programmers control the precise movements of each joint by controlling the steps of the motor.
Electric stepper motors power robotic arms with speed and accuracy. At times, robotic arms lift heavy objects. Pneumatic and hydraulic power supply the extra force Pneumatic and hydraulic actuators use compressed air (pneumatic force) or hydraulic fluids (hydraulic force) to transfer power to the joints and grippers. Pneumatic and hydraulic systems are made up of cylinders and pistons, much like a doctor's syringe. The piston pushes on the fluid in the cylinder. A second piston on the other end of the cylinder moves as the fluid presses on it. The moving piston can make the robotic arms move forward and back. The pistons are controlled by electrical switches connected to computers. The switches open and close valves controlling air and hydraulic fluids.
CONTROLLING ROBOTIC SYSTEMS
Cables of wire travel from the computer to the robotic interface. The interface links the robotic motors to the computer. Inside the interface are electronic switches that turn the motors on and off. Electrical signals travel through the cable as coded information. The code consists of bursts of electrical current. When written, the code is represented by a series of 0's and 1's. This code is commonly referred to as binary code.
How does a robotic arm know what movements to make? How much pressure should the gripper apply? How can a robotic arm "remember" the patterns needed to paint an automobile?
Just as your brain controls your every movement, so do computers control the movement of robotic systems. The computer uses a series of instructions known as a program. Robotic programs are very complex. They must list in logical order all the steps needed for the robot to perform a task. Imagine listing each command that the brain sends to muscles when you pour milk from a container into a glass. Robotic software (program) designers prepare flowcharts that list the basic movements of a robot. These movements are then broken down into finer detail. They are then written in a language that computers can understand.
Computers send instruction to the actuators that power the movement of the joints. The instructions tell the robotic arm how far to travel, how much pressure to apply, and how to move a tool to perform a task. The instructions are sent as electronic signals that rotate stepper motors or open pneumatic valves, causing the pistons to travel. Robotic programmers write the computer instructions or software to control robotic hardware. Instructions can be created by guiding the robotic arm through a sequence of movements and programming the computer to remember the patterns of motion. Teaching a robot in this manner is called lead-through programming. Robots can also be programmed using keyboards or teach pendants. The pendant and keyboard give the robot direct instructions to move up, down, left, and right. Each movement is remembered by the computer and repeated as often as required.
How does a robot know where an item is? Humans have sensory organs such as eyes, skin, and ears. These allow us to track changes in our environment. Robots also have sensors so they can keep track of what's going on around them. Imagine that you are going to touch the handle of a saucepan on a stove. Your brain sends signals to the muscles and tendons in your hand to grasp the pot handle. Information is quickly sent to your brain through nerve bundles. The message is that your hand had grasped the handle and is ready for the next command.
What if the handle is too hot? If the handle is too hot, signals quickly return to your brain. There, they are translated as pain signals. Your brain sends new signals to your hand and your grip is released. The process of sending signals, interpreting received signals, and adjusting through signals is called feedback control. Robots use feedback control constantly. It allows them to know where they are and to adjust their actions.
Your fingers have over 17,000 sensors (nerve endings) that send data to your brain as you touch things. Robots use touch sensors known as contact sensors. These feed information back to the computer about a task that it is working on. Contact sensors send electrical signals to the computer. The data might include information on the shape of an object and how much pressure the grippers are placing on it. The computer can adjust the actions of the robot if changes are needed.
A robot may be equipped with cameras so it can view objects in the work envelope. The image picked up by the camera is the input. It is sent to the computer for analysis. Using that data, the computer outputs directions to the robot. Imagine freshly baked cookies moving down a conveyor line. Using its attached camera, the robotic arm looks for burnt and broken cookies. When one is sighted, the computer instructs the grippers to remove the bad cookie from the line.
Robotic arms that perform detailed work like welding or painting use angular or optical sensors. These track the arm's movement. These sensors, which are shaped like disks, have markings. The disks are placed at each joint in the robotic arm. As the joint moves, optical scanners (like cameras) read the code. They send this information to the computer. The computer interprets the information, calculates the angle of the joint, and outputs the needed command for the arm.
Probably the most famous robot arm, seen hard at work by millions of people, is the Remote Manipulator System (RMS) used aboard the Space Shuttle (see below). The RMS is a jointed robotic arm. It uses cameras and angle sensors to tell the computer its position. The arm can be used to release satellites into space as well as retrieve items already in orbit. The RMS can also serve as a remote work platform for doing repair work on space vehicles. Robots may also use sonar to measure distances. They use sensors to detect poisonous materials in the work envelope. These semsors are called non-contact sensors.
In the darkness of space, the Hubble Telescope is lifted by the remote manipulator system (RMS) from its berth in the cargo bay of the Earth-orbiting Space Shuttle Discovery. The orbiter uses electric motors to position its robotic arm. Video cameras help the astronauts view the arm as they manually move it towards its target.
A CLOSER LOOK
Some jobs are better done by robots. They are used, for example, for welding jobs in automobile assembly. They are also used for drilling precise holes in hip-replacement surgery. The way that machines interact with people has become an important dimension of technology. In the future, control by voice commands will become more widespread. Cog is the name of the humanoid robot shown below. It is programmed to mimic human movements and senses.
Rover Sojourner This solar-powered robotic vehicle was used by NASA to study the composition of soil and rocks on Mars. Controlled by computer, It could steer itself to avoid obstacles. It provided regular location updates.
ROBOT ANTS These one-inch robots contain tiny motors for locomotion and grasping. When it detects food, the robot ant sends out an electronic signal, which summons other ants. Robots that cooperate in imitation of social insects could be ideal for collecting toxic waste for disposal.
The first generation of robots was designed by industry to perform a variety of tasks. Known as red collar workers, these robots did simple tasks that were dangerous or unpleasant for human workers. Early robots were used to handle hot metal, weld metal parts, spray-paint, move parts, and load pallets. These early robots were large and not very flexible.
The second-generation robots used today can perform tasks more complex than the tasks performed by early robots. Today's robots are more flexible. They can be quickly taught to do several different operations. With movements accurate to a fraction of a millimeter, robotic arms can assemble intricate electronic circuits. They can solder wires as thin as a human hair.
Doc Beardsley's animatronic body gives him mobility and facial expressions. Unlike ordinary animatronic figures, however, Doc can see, hear and hold up his end of a conversation.
Are there negative impacts of the use of technology? What if your friend worked in a factory that assembled automobiles? She performs her job with the greatest accuracy and never misses work. Her supervisor often tells her that she is the most productive employee in the company. One day when your friend goes to work, She walks onto the assembly line floor to find a shiny robotic arm in her spot. The arm works twice as fast as your friend. It takes no breaks, and works twenty-four hours a day. Your friend has been displaced. "Displaced" is a term used to describe a person whose job has been taken over by automation or new technology. Many experts tell us that robotic technology may cause increased unemployment as companies switch to automation.
Others say that being displaced is not the same as being dismissed. Displaced employees usually find new work within the same company or with other companies that are not yet automated.
The use of robots in business and industry is part of the automation revolution. Automation is the process by which computers control a series of tasks in manufacturing. Automated factories can operate with very few people. Automated machines can usually work faster, at lower cost, and more accurately than human workers. Remember that robots are not paid a salary, are never late, never call in sick, never need health insurance, and never take vacations.
Robotic automation now allows manufacturers to produce products more cheaply. This allows products to be sold for less. This allows the manufacturer to become more competitive in the world market. In the future, the use of robots will increase.