This article is an overview of robots, and explains what they are from a general point of view.

A robot may include a feedback-driven connection between sense and action, not under direct human control. The action may take the form of electro-magnetic motors or actuators (also called effectors) that move an arm, open and close grips, or propel the robot. The step by step control and feedback is provided by a computer program run on either an external or embedded computer or a microcontroller. By this definition, a robot may include nearly all automated devices.

Two basic ways of using effectors are to move the robot around (locomotion) or to move other object around (manipulation) These divide robotics into two mostly separate categories: mobile robotics (moving) and manipulator robotics (grabbing).

Joints connect parts of manipulators. The most common joint types are:

rotary (rotation around a fixed axis)
prismatic (linear movement)
A parallel robot is one whose arms (primary axes) have three concurrent prismatic joints or both prismatic and rotary joints. Degrees of freedom (DOF) means axes of movement. The human arm has 7 DOF. A 6 DOF arm is highly flexible.

Proprioceptive sensors sense the robot's actuators (e.g., shaft encoders, joint angle sensors). Proprioception is one of the most important senses of the human body.

Alternately, robot has been used as the general term for a mechanical man, or an automaton resembling an animal, either real or imaginary. It has come to be applied to many machines which directly replace a human or animal in work or play. In this way, a robot can be seen as a form of biomimicry. Lack of anthropomorphism is perhaps what makes us reluctant to refer to the highly complex modern washer-dryer as a robot. However, in modern understanding, the term implies a degree of autonomy that would exclude many automatic machine tools from being called robots. It is the search for ever more highly autonomous robots which is the major focus of robotics research and which drives much work in artificial intelligence.

Though we tend to think of robots as tremendously sophisticated, thanks typically to their anthropomorphic physical design and our excess of indoctrination to the robots of 1960s television, the fundamental elements are very simple. Motion is achieved by motors controlled by digital circuits that incorporate a key power semiconductor switching element called a thyristor or silicon-controlled rectifier (SCR). The robot turns when only one of two parallel motors is actuated: for example, stopping the left motor while running the right motor causes the dummy to turn left. Digital signals fed to the motor control circuitry determine which motors move at which times. The problem can range from very simple (e.g., turning left or right) to very complex (e.g., controlling an elbow and wrist to move an item from a conveyor belt to a shelf). The signals can be sent by an outside element (e.g., a human operator) or by internal circuitry that makes "decisions" based upon observations of the robot's environment and may alter these decisions based upon whether the motion is proceeding satisfactorily (see feedback).

Underlying simplicities notwithstanding, combinations of various computer systems and electromechanical subsystems can produce the appearance of profound sophistication, e.g., a "chess-playing robot" that really should be viewed as two discrete systems: (1) chess-playing software that has nothing to do with robotics; and (2) a robot that interacts with the chess board. The latter requires the abilities to [a] locate a chessman on the board based upon its expected coordinates, [b] lift the man, [c] remove any captured man from the board, and [d] reposition the first man--all without breaking or knocking down chess pieces or committing other environmental faux pas.

The term robot is also often used to refer to sophisticated mechanical devices that are remotely controlled by human beings, such as waldoes and ROVs, even though these devices are not autonomous.

Other interesting information about Medical Robotics or Robotic-assisted Surgery