What is a Robot

The sense-think-act loop and the anatomy of an embodied machine

The sense-think-act loop

Every robot, from a warehouse arm to a humanoid, runs the same fundamental loop:

1. Sense — Gather information about the world through sensors.
2. Think — Decide what to do based on that information.
3. Act — Change the world through actuators.

This loop runs continuously, often hundreds of times per second. What separates a robot from other machines is that its actions feed back into what it senses — it operates in a closed loop with the physical world.

Anatomy of a robot

A robot is composed of a few essential subsystems:

• Structure — The body: frame, joints, and links that give the robot its shape and workspace.
• Sensors — The perception layer: cameras, encoders, IMUs, force sensors.
• Actuators — The muscles: motors, servos, and drivers that produce motion.
• Compute — The brain: from microcontrollers running control loops to GPUs running learned policies.
• Power — Batteries or tethers, and the electronics that distribute energy safely.

Each subsystem is a building block. Understanding how they compose is the foundation for everything else in this manual.