ines similar to a crane. Robots are usually kept stationary. But if a robot moves most of the time that is all it does. Examples are delivery robots rolling down halls delivering mail or supplies. Most robots are blind and are insensitive to their surroundings. Some other do have sensors triggered by light, pressure, or heat that can create a crude picture of what is happening in their surroundings. More or less it is not nesary for them to know what is happing to their surroundings. ROBOTIC ARMS There are four types of robot arms that are used today, they are rectangular arms, cylindrical arm, spherical arm, and jointed-arm . These arms have specific perpouses that are apapted for the perpouse. 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 thirddimension. 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 that 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...
