Robotics Fundamentals
What Is a Robot?
A plain-language introduction to what a robot actually is: a machine that senses the world, decides what to do and acts on it. And how that differs from an ordinary machine.
beginner · 10 min read
Lesson content
Forget the movies for a moment.
A robot is a machine that can do three things. It senses what is around it. It decides what to do about that. Then it acts to change something. All of this without a person steering every move.
That is the whole idea. Strip away the metal skin and the science fiction and a robot is just those three abilities running in a loop, over and over, a few dozen times a second.
Definition
Robot
A machine that senses its environment, processes what it senses to make a decision, then acts physically on the world with some degree of autonomy.
Formal definition
A programmable machine capable of carrying out a series of actions autonomously or semi-autonomously by sensing its environment, computing a response and actuating physical outputs.
Isn't my washing machine a robot, then?
Almost. But not quite.
A basic washing machine follows a timer. Thirty minutes of wash, ten of spin, the same every time. It has no way of telling whether the clothes actually came out clean. It acts, but it does not really sense or decide.
A robot closes that loop. It reads the world, picks what to do based on what it read and can do something different next time because the situation is different.
Add a turbidity sensor, plus logic that keeps washing until the water runs clear. Your washing machine has just become a robot. A very boring one, but a real one.
A robot is like a driver, not a train
A train follows its track. It goes exactly where the rails lead, every time and it cannot do anything else.
A driver watches the road. A child runs out, a light turns red, a lane is closed. The driver reacts, then picks a new route.
A robot is the driver, not the train. It takes in what is happening and chooses its next move instead of following a fixed track.
- Sense
Reading the world and the robot's own body, through sensors.
Without sensing, a machine can only ever repeat itself. It has nothing to react to.
- Think
Turning sensor readings into a decision, using a program or a controller.
This is where a robot's behaviour lives. The same body can act very differently with different code.
- Act
Changing the physical world using actuators like motors.
Acting on the physical world is what separates a robot from a pure software program.
- Autonomy
How much a robot does on its own, without a human deciding each step.
More autonomy means the robot handles more situations by itself. It is a spectrum rather than a yes or no.
Example
A robot vacuum, in three abilities
Senses: bump switches on the front and a downward-looking cliff sensor so it does not fall down the stairs.
Thinks: hit a wall? Turn. Edge of a step? Back up.
Acts: drives its wheels, spins its brush.
Now the interesting part. Change none of the hardware, not one screw and rewrite only the program. The same vacuum can cover the room in neat rows instead of random turns.
Same body, completely different behaviour. That is proof of where a robot really lives: in the think step.
| Ordinary machine | Robot | |
|---|---|---|
| Senses its surroundings | No | Yes |
| Decides based on what it senses | No | Yes |
| Acts physically on the world | Yes | Yes |
| Can react to a new situation | No | Yes |
Senses its surroundings
- Ordinary machine
- No
- Robot
- Yes
Decides based on what it senses
- Ordinary machine
- No
- Robot
- Yes
Acts physically on the world
- Ordinary machine
- Yes
- Robot
- Yes
Can react to a new situation
- Ordinary machine
- No
- Robot
- Yes
Thinking a robot has to look human, or look like anything in particular.
Most real robots are arms bolted to a floor, wheeled boxes, or flying frames. Shape follows the job rather than the movies.
Assuming a robot must be fully autonomous to count.
Autonomy is a spectrum. A surgical robot guided by a surgeon and a self-driving car are both robots. They just sit at different points on it.
Key takeaway
- A robot senses the world, decides what to do, then acts on it, all in a loop.
- The "decide" step is what separates a robot from a machine that only repeats itself.
- Robots don't have to look human. Their shape follows their task.
- Autonomy is a spectrum, from remote-controlled to fully self-driving.
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