What is a ROBOT?
The Robot Institute of America designates a robot as “a reprogrammable, multifunctional manipulator, designed to move material, parts, tools, or specialized devices through various programmed motions for the performance of a variety of tasks". The ISO defines ROBOT as “an automatically controlled, reprogrammable, multipurpose manipulator with three or more axes.” A robot on simple words is “a machine that does mechanical, routine tasks on human command”. The word robot is derived from robata, a Czech word meaning compulsory labor or servitude. The science and technology of designing, building, and programming robots is called Robotics.
Robotic devices, or robots, as they are usually called, are primarily smart machines with manipulators that can be programmed to do a variety of manual or human labor tasks automatically and with sensors.
Primary Components of robot
A typical robot normally consists of:
- One or more manipulators (arms),
- End effectors (hands),
- A controller,
- A power supply, and
- An array of sensors to provide information about the environment in which the robot must operate.
Many different types of manipulator arms have been developed to accomplish robot motions. The four major types of manipulator arms are the rectangular, cylindrical, spherical, and anthropomorphic (articulated or jointed arm). Each of these manipulator arm designs features two or more degrees of freedom (DOF)—a term that refers to the direction a robot’s manipulator arm is able to move. For example, simple straight line or linear movement represents one DOF.
If the manipulator arm is to follow a two-dimensional curved path, it needs two degrees of freedom: up and down and right and left.
Fig – Manipulator
To locate an end effector at any point and to orient this effector in a particular work volume requires six DOF. If the manipulator arm needs to avoid obstacles or other equipment, even more degrees of freedom are required.
For each DOF, one linear or rotary joint is needed. Robot designers sometimes combine two or more of these four basic manipulator arm configurations to increase the versatility of a particular robot’s manipulator.
Actuators are used to move a robot’s manipulator joints. Three basic types of actuators currently are used in contemporary robots: pneumatic, hydraulic, and electrical.Pneumatic actuators employ a pressurized gas to move the manipulator joint. This kind of actuator is found most often in nonservo, or pick-and-place robots.Hydraulic actuators are quite common and capable of producing a large amount of power.Electric motor-driven actuators provide smoother movements, can be controlled very accurately, and are very reliable.
Many industrial robots are fixed in place or move along rails and guide ways. Some terrestrial robots are built into wheeled carts, while others use their end effectors to grasp handholds and pull themselves along. Advanced robots use articulated manipulators as legs to achieve a walking motion.
A robot’s end effector (hand or gripping device) generally is attached to the end of the manipulator arm. Typical functions of this end effector include grasping, pushing and pulling, twisting, using tools, performing insertions, and various types of assembly activities.
Fig- End Effectors
End effectors can be mechanical, vacuum, or magnetically operated, can use a snare device or have some other unusual design feature. The shapes of the objects that the robot must grasp determine the final design of the end effector. Usually most end effectors are some type of gripping or clamping device.The actions that can be produced by the end effector or hand include: (1) motion (from point to point, along a desired trajectory or along a contoured surface); (2) a change in orientation; and (3) rotation.
Most industrial robots derive their primary electric power from the available electric grid that services the factory, laboratory, or facility. On Earth, mobile robots that are remotely operated by cable links can be provided electric power (via tethered lines) from a portable generator in the field or from a source of commercial (wall-power) in laboratory, industrial, or urban operational environments.
Untetherd, remotely operated mobile robots (those that use radio signals for control) must contain their own source of primary power, usually batteries or fuel cells. In some cases – such as remotely operated, heavy-duty mobile robots—the robot vehicle is propelled by a diesel or gasoline-powered engine, which also generates onboard electric power. Submersible mobile robots either obtain their electric power via cables from the surface ship.
Space robots (The robots which are send to space) of all types must provide their own electric power. For these robot systems, electric power is generated in a variety of ways, including the use of long-lived batteries, solar cells, or radioisotope thermoelectric generators—depending on the needs and location of the specific mission.
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