How robots act

If sensors are how a robot perceives, actuators are how it acts on the world. The most common is the motor, which creates movement. Others include:

• Motors and wheels: to drive
• Servo motors: to turn to an exact angle, like a robot arm joint
• Buzzers and lights: to signal
• Relays: to switch other devices on and off

The controller sends a signal to an actuator to make it act, for example "spin the left motor forward". Sensing plus acting, joined by a decision, is the whole game.

Practice

For the water tank alarm you imagined earlier, which actuator would you use to warn people, and why that one?