Want to keep learning?

This content is taken from the University of Reading's online course, Begin Robotics. Join the course to learn more.
Baxter robot picking up ping pong balls
Baxter robot

Sensors and Actuators

Sensors are devices which measure quantities which the robot can use to achieve given tasks.

Examples of what a robot may need to determine include:

  • How far away and where is an object (like another robot, a light, a wall)?
  • At what speed is the robot moving?
  • If the robot is on a hill, at what angle is it?
  • If the robot is rotating, by how much has it rotated?
  • Where is the robot, or in what direction is it going?
  • How far it has it travelled (which is odometry)?
  • How much power has it consumed?
  • What information is being communicated to the robot?

The robot may require internal and external sensors.

External sensors are used to measure other objects, for instance:

  • How far away is an object?
  • Where is the object?

Internal sensors are used to measure the robot itself, for instance:

  • How fast it is going
  • The angle of the robot
  • Where it’s ‘gripper’ is
  • How much power it’s consuming


An actuator is a device which causes something to happen.

This could be a robot movement, which is often achieved using motors:

  • An actuator is needed to make the robots wheels turn.
  • Or the joints of a robot arm to rotate.
  • Or for a robot gripper to open or close.

Or it could be to let the others know what the robot is doing.

  • A light being turned on to indicate the robot is working.
  • Sound is being emitted - so the actuator is a loudspeaker.
  • Communication in some form - so a transmitter is needed.
  • An LCD (Liquid Crystal Display) screen for showing pictures and other data.

Share this article:

This article is from the free online course:

Begin Robotics

University of Reading

Get a taste of this course

Find out what this course is like by previewing some of the course steps before you join: