EVALUATION OF ROBOTS
The word robot first appeared in print in the 1920 play R.U.R. (Rossum’s Universal Robots) by Karl Kapek, a Czechoslovakian playwright. Robota is Czechoslovakian for worker or serf (peasant). Typical of early science fiction, the robots take over and exterminate the human race.
1954: The first programmable robot is designed by George Devol, who coins the term Universal Automation. He later shortens this to Unimation, which becomes the name of the first robot company (1962).
Isaac Asimov popularized the term robotics through many science - fiction novels and short stories.Asimov is a visionary who envisioned in the 1930’ s the positronic brain for controlling robots;this pre - dated digital computers by a couple of decades.Unlike earlier robots in science fiction, robots do not threaten humans since Asimov invented the three laws of robotics:
3. Types and classification of robots.
Industrial robots are available commercially in a wide range of sizes, shapes, and configurations. They are designed and fabricated with different design configurations and a different number of axes or degrees of freedom. These factors of a robot’s design influence its working envelope
Common Robot Designs 4.1. Cartesian
Robots which have three linear (prismatic joints P, as opposed to rotational R joints) axes of movement (X, Y, Z). Used for pick and place tasks and to move heavy loads. They can trace out rectangular volumes in 3D space.
The positions of these robots are controlled by a height, an angle, and a radius (that is, two P joints and one R joint). These robots are commonly used in assembly tasks and can trace out concentric cylinders in 3D space.
Spherical robots have two rotational R axes and one translational P (radius) axis. The robots’ end-effectors can trace out concentric spheres in 3D space.
The positions of articulated robots are controlled by three angles, via R joints. These robots resemble the human arm (they are anthropomorphic). They are the most versatile robots, but also the most difficult to program
4.5 SCARA (Selective Compliance Articulated Robot Arm)
SCARA robots are a blend of the articulated and cylindrical robots, providing the benefits of each. The robot arm unit can move up and down, and at an angle around the axis of the cylinder just as in a cylindrical robot, but the arm itself is jointed like a revolute coordinate robot to allow precise and rapid positioning. The robot consists of three R and one P joints; an example is shown belowWe will mostly deal with robotic arms; some other interesting types of robots are mobile robots, humanoid robots, and parallel robots.
4.6. Mobile robots
Mobile robots have wheels, legs, or other means to navigate around the workspace under control. Mobile robots are applied as hospital helpmates and lawn mowers, among other possibilities. These robots require good sensors to “see” the workspace, avoid collisions, and get the job done.
4.7. Parallel robots
Most of the robots discussed so far are serial robots, where joints and links are constructed in a serial fashion from the base, with one path leading out to the end-effector. In contrast, parallel robots have many “legs” with active and passive joints and links, supporting the load in parallel. Parallel robots can handle higher loads with greater accuracy, higher speeds, and lighter robot weight; however, a major drawback is that the workspace of parallel robots is severely restricted compared to equivalent serial robots. Parallel robots are used in expensive flight simulators, as machining tools, and can be used for high-accuracy, high-repeatability, high-precision robotic surgery.