Sensors and Actuators

How robots perceive the world and move within it

Sensors: the perception layer

Sensors convert physical phenomena into signals a robot can process. The most common families:

• Proprioceptive sensors measure the robot's own state — joint encoders, IMUs (inertial measurement units), and current sensors.
• Exteroceptive sensors measure the world — cameras, LiDAR, depth sensors, microphones, and tactile arrays.

No single sensor is sufficient. Real systems fuse multiple sensor streams to build a coherent picture of both the robot's state and its environment.

Actuators: producing motion

Actuators convert energy into movement. The main types you'll encounter:

• Electric motors — DC, brushless (BLDC), and stepper motors; the workhorses of modern robotics.
• Servos — Motors packaged with feedback control, trading raw performance for simplicity.
• Linear actuators — For pushing, pulling, and lifting in a straight line.

The choice of actuator shapes everything downstream: torque and speed limits, control strategy, power budget, and even the robot's safety characteristics.

Closing the loop

Sensors and actuators meet in the control loop: sense the current state, compare it to the desired state, and command the actuators to close the gap. This feedback principle — measure, compare, correct — is the beating heart of every robot.