What is a robot?

The official definition

Robot makers and statisticians use a shared definition. The International Federation of Robotics says its members use the vocabulary standard ISO 8373, which defines a robot as "a programmed actuated mechanism with a degree of autonomy to perform locomotion, manipulation or positioning".^[2]

The current edition is ISO 8373:2021. ISO says a revised edition is being prepared.^[1]

Each part of the definition matters. "Actuated" means the machine has actuatorsA part that makes a robot move, usually an electric motor with gears. that move it: the textbook Modern Robotics says these are typically electric motors, though pneumatic or hydraulic cylinders are also used. "Locomotion, manipulation or positioning" means it moves itself, handles things, or puts things in place.^{[2] [8]}

"A degree of autonomy" is defined too: the "ability to perform intended tasks based on current state and sensing, without human intervention". A robot does not have to be fully independent. For service robots, the IFR says autonomy ranges from partial, with people involved, to full.^[3]

Modern Robotics puts the core idea simply: robotics often includes artificial intelligenceComputer systems that do tasks which usually need human judgment, such as recognizing pictures or writing text. and computer perception, but an essential feature of any robot is that it moves in the physical world.^[8]

Robot or not?

Try applying the definition yourself. Some everyday machines fit it, some are robotic devices, and some are something else.

Three official kinds of robot

ISO 8373:2021 sorts robots by what they are used for, and the IFR says it added medical robots as a third category next to industrial and service robots.^[3]

• Industrial robot: an automatically controlled, reprogrammable multipurpose manipulator, programmable in three or more axes, used for automation in an industrial environment. It can be fixed in place or mounted on a mobile platform.^[4]
• Service robot: a "robot in personal use or professional use that performs useful tasks for humans or equipment". Professional cleaning robots are one example the IFR counts.^{[3] [6]}
• Medical robot: the third category in ISO 8373:2021.^[3]

Robots and robotic devices

Some machines look like robots but do not meet every part of the definition. The IFR says these are called robotic devices, and gives examples: a teleoperatedA person controlling a robot remotely instead of the robot acting on its own. remote manipulator, a haptic device, an end-effector such as a gripper on its own, and an unpowered exoskeleton.^{[3] [8]}

The line is not always sharp in practice. The IFR says its service robot statistics include systems with some human interaction or even full teleoperation, as well as fully autonomous ones, depending on the application.^[3]

So when you see a "robot" in a video, it is worth asking whether it is acting on its own or whether a person is steering it. The page on teleoperation and autonomy goes into this.

What a robot is made of

Modern Robotics says that at its most basic level a robot consists of rigid bodies connected by joints, with the joints driven by actuatorsA part that makes a robot move, usually an electric motor with gears..^[8]

It adds that robots are equipped with sensors to measure the motion at their joints, and may carry more sensors, such as ordinary cameras and depth (RGB-D) cameras, to locate objects or themselves.^[8]

Body, actuators, sensors and a program: the pages on robot sensors, motors and decision-making look at each part in turn.

Where the word comes from

The word is younger than you might think. Britannica says the Czech writer Karel Čapek invented it for his play R.U.R., published in 1920 and performed in 1921, deriving it from the Czech word for forced labour.^[5]

How many robots are there?

The International Federation of Robotics publishes yearly counts. These figures change every year, so they are shown with the date we checked them.