How Do Robots Work? The Sense-Think-Act Loop in Plain English
Every robot, from a vacuum cleaner to a factory arm, runs the same three-step loop. Here is how it works, with everyday examples.
Short answer: a robot repeats a loop thousands of times a second: it senses the world, thinks about what to do, then acts. Sensors are the eyes and ears, a computer is the brain, and motors are the muscles. See the Sense-Think-Act loop in the Atlas for the formal version.
The three steps
1. Sense. Sensors turn the world into numbers. A lidar measures distance with laser pulses, a camera captures images, an encoder counts wheel turns.
2. Think. Software decides what to do with those numbers. It might be a few lines ("if the wall is closer than 20 cm, turn") or a large neural network.
3. Act. The computer commands actuators, such as a DC motor, to move. The movement changes the world, and the loop starts again.
A robot vacuum, step by step
- Sense: bump sensors and a distance sensor notice a chair leg.
- Think: the software marks the spot on its map and picks a path around it.
- Act: the wheel motors steer left.
Half a second later it senses the new position, and the loop repeats.
Why the loop matters
Reality is messy: wheels slip, sensors are noisy, people walk in the way. Because the robot keeps sensing, it can correct itself. This idea is called feedback. A robot without it is just a machine replaying a recording, which works only until something changes.
What goes wrong without it
A toy that drives forward for exactly 3 seconds will hit the wall if the floor is slippery. A robot that senses distance will stop in time. That difference is the whole point of sensing.
FAQ
Is a thermostat a robot? It senses and acts, but most definitions also want a physical body that does work in the world and some decision-making. It is a simple control system, not usually called a robot.
Do robots need AI? No. Many industrial robots follow fixed programs. AI helps when the world is unpredictable, for example recognising objects.
What is the best way to start learning? Build the loop yourself in a simulator, then on a small board such as an Arduino. Try Lesson 1 of the free Spark track in the Academy.
Keep learning
See how AI fits in: AI and robotics, the complete guide.
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