What Is A Robot Essays - Robot, Industrial Robot, Mobile Robot

What is A Robot 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.