Guide
How robots work: a beginner's guide for BattleBots fans
The short answer: every robot, from a 3 lb combat bot to a walking humanoid, runs the same loop: sense, decide, act. A BattleBot leaves the "decide" step to a human holding a radio. Most of what's new in robotics is moving that decision into the robot itself, with backdrivable electric motors, better sensors, and AI that learns from simulation and data.
Part 1: Why I'm learning robots in public
Picture the BattleBox. Two robots roll in, the countdown hits zero, a spinner winds up, and a wedge drives straight at it. Sparks. A chunk of metal slams into the wall. The whole crowd is on its feet.
Every one of those robots had a person behind it, thumbs on a radio, making every call.
That's changing. Robots are starting to make their own calls: where to step, what to grab, how to get back up after a fall. They're leaving the arena and showing up in warehouses, labs, and on sidewalks.
I want to understand that while it's happening, and I mean how it actually works, not the launch-video version.
I'm not an engineer. I don't have a robotics degree. So I'm teaching myself, and I'm writing down what I learn as I go. That's Servospace.
Why do it in public? Because it keeps me honest. When I write something you're going to read, I have to check it. I have to link where I got it. I have to admit when I don't get it yet. And when I get something wrong, someone will tell me, and I'll fix it where you can see it.
Why should you care? Most robotics writing is either for engineers or for hype. There isn't much for someone who's curious and starting from zero. I'm close to zero too. I'm a few steps ahead at most, and happy to say so.
I'll be skeptical of demos. A great video isn't a shipped product. I'll keep asking whether it was sped up, remote-controlled, or the one good take out of fifty.
That's it. Below is the guide I wish I'd had on day one.
Part 2: The beginner's guide
The one idea that connects them all
Every robot does three things over and over:
- Sense: figure out what's going on (where am I, what's around me, how are my joints bent).
- Decide: pick what to do next.
- Act: spin a motor, move a leg, close a hand.
A BattleBot hands the "decide" step to a human driver. Modern robots try to make that decision themselves, hundreds of times a second.
Here's how the parts on a BattleBot map to the parts in today's headlines:
| On a BattleBot | On a modern robot | What it's doing |
|---|---|---|
| Drive motors and wheels | Joint actuators in legs and arms | Turning electricity into motion |
| The driver's eyes | Cameras, depth sensors, lidar | Seeing the world |
| The driver's gut feel for "I'm flipped" | IMU (an accelerometer and gyroscope) | Knowing which way is up |
| The driver's thumbs | Control software | Turning goals into motor commands |
| Weapon | Hands, grippers, tools | Doing the actual job |
| Batteries | Batteries (still) | Still the thing everyone wishes were better |
A quick history of robot fights on TV
BattleBots premiered on Comedy Central on August 23, 2000, and ran for five seasons through 2002. It came back on ABC in 2015 and moved to Discovery Channel in 2018 (Wikipedia). In the UK, Robot Wars started on BBC Two in 1998 (RobotCombatWiki).
The three kinds of robot you'll keep seeing
Combat robots
BattleBots launched a 20-episode Pro League in 2026 that streams free on YouTube (Business Wire).
The TV bots are heavyweights, around 250 lb. Most newcomers start much smaller. The National Havoc Robot League (NHRL) in Norwalk, Connecticut, runs open tournaments in 3, 12 and 30 lb classes (NHRL rules). Its starter guide says a capable 3 lb bot can be built for around $400, mostly from 3D-printed plastic and off-the-shelf RC car and drone motors (NHRL wiki).
Combat bots are almost always remote-controlled, and that's the point: the sport is about mechanical design under brutal conditions. That's starting to shift, though. BattleBots' Pro League lineup includes Orbitron from Canada, which BattleBots bills as "the world's first AI-controlled robot" (Business Wire). That moves the "decide" step from the driver into the machine.
Quadrupeds: robot dogs
Four legs are easier than two. A dog-shaped robot can stand still without falling over, which buys a lot of forgiveness.
Boston Dynamics' Spot is the famous one. It sees with five stereo depth-camera pairs: two in front, one on each side, and one in back (Boston Dynamics). At the cheap end, Unitree's online store lists the Go2 Air from $1,600 before shipping, as of October 31, 2026 (Unitree store).
MIT's Mini Cheetah is the one to study. It weighs about 20 lb (9 kg), and in 2019 it became the first four-legged robot to do a backflip (MIT; ICRA 2019 paper). Each of its 12 motors is "about the size of a Mason jar lid." Those motors come up again below.
Humanoids: robots shaped like us
Humanoids are the hardest and the most hyped. Why build a robot shaped like a person? Because the world is already built for people: stairs, door handles, shelves, tools. In theory, a humanoid can work in a warehouse without the warehouse changing.
A few you'll see in the news:
- Atlas (Boston Dynamics). The old hydraulic Atlas, the one that did parkour, retired in April 2024. An all-electric version replaced it, aimed at real work starting with Hyundai's factories (Boston Dynamics).
- Digit (Agility Robotics). One of the few humanoids doing paid commercial work, including with logistics company GXO. Agility expects to start trading on Nasdaq on November 5, 2026 (Agility; our story).
- Unitree G1. A small humanoid you can actually buy. Unitree's store lists it at $13,500 before shipping, as of October 31, 2026 (Unitree store).
- Meta's "Max" (reported). The Information reports that Meta built a humanoid prototype with Chinese robot maker Fourier. Meta says it's internal research and not for sale (our story).
Real or hype? Three questions for any robot video
| Ask | Why it matters | Where to look |
|---|---|---|
| Is it sped up? | 2x footage makes slow robots look capable | Caption, on-screen "2x" or "4x" label |
| Is someone teleoperating it? | A human may be making the decisions, BattleBots-style | Caption, fine print, the company's blog post |
| Is it doing the task once or all day? | One clean take can hide dozens of failures | Whether the company reports hours, shifts, or paying customers |
How they actually work
Actuators: the muscles
On a BattleBot, a motor spins a wheel, and that's mostly it. On a walking robot, every joint needs a motor that can push and be pushed back.
Here's how the Mini Cheetah's motors work. Each one is a brushless motor with a small 6:1 gearbox (MIT). That's a deliberately low gear ratio. A big gear reduction gives you lots of torque but makes the joint stiff, like trying to turn a car's wheels with the engine off. A low ratio keeps the joint "backdrivable." When the foot slams into the ground, the motor gives a little instead of breaking, and the robot can feel the impact through the motor current. MIT's researchers called this proprioceptive actuation (MIT Cheetah actuator paper). It's often called quasi-direct drive.
If you've built a combat bot, you know this trade-off from the other side. A gearbox that gives your lifter enough torque also makes it slow and fragile under shock. Same physics, different stakes.
Older robots like the original Atlas used hydraulics, which are very strong but messy and complex. The industry has moved toward electric motors, and Atlas itself went electric in 2024.
Sensors: the senses
Robots need two kinds of sense:
- Looking outward: cameras, depth cameras, and lidar (a laser rangefinder) to map the room and spot obstacles.
- Looking inward: encoders that measure each joint's angle, and an IMU that measures tilt and acceleration. Your inner ear does the IMU's job for you.
The inward senses are underrated. A walking robot depends on knowing exactly how its own body is moving, often more than on what its cameras see.
Control: the reflexes
Control is the software that turns "walk forward" into thousands of tiny motor commands. The classic approach is to model the physics and solve for the best move many times a second. Using a method called model-predictive control, the Mini Cheetah ran at up to 2.45 m/s (ICRA 2019 paper).
The newer approach is to let the robot learn. In 2021, researchers at ETH Zurich simulated thousands of robot dogs in parallel on a single graphics card. Their quadruped learned to walk on flat ground in under four minutes of training and on rough terrain in about twenty, and the learned controller was then moved onto the real robot (Rudin et al., CoRL 2021). That's called sim-to-real, and it's a big reason legged robots improved so quickly.
AI: the part that's changing fastest
Walking is a reflex. Knowing what to do, like "put the apple in the bowl," is a different problem.
In 2023, Google DeepMind showed RT-2, a model that takes camera images and a plain-language instruction and outputs robot actions directly. It does this by treating motor commands like words in a sentence (Google DeepMind). Models like this are called vision-language-action models, and many humanoid companies are betting on some version of the idea.
A rough way to think about it: classic control keeps the robot upright, learned policies give it athletic skills, and big AI models are starting to give it common sense. That last layer is the least finished.
Where to start
You don't need a lab. Pick the path that matches what got you into robots in the first place.
If you loved the fights, build a small combat bot.
- Read NHRL's Combat Robotics Starter's Guide. It's straightforward about cost and safety, and it says the 30 lb class is not recommended for new competitors.
- Consider a kit for your first bot. Just 'Cuz Robotics sells the SSP 2.0, a 3 lb kit pitched at beginners, listed at $450 as of October 31, 2026. You'll still need a LiPo charger and a radio. NHRL's guide warns that kit bots won't win tournaments and can cost more than designing your own. Its guide also says you learn more from losing than from winning.
- Enter NHRL's 3 lb "XP" tournament, which runs alongside its regular Open events and is meant for less experienced competitors (NHRL wiki).
If you want to understand AI robots, build an arm.
- Hugging Face's open-source LeRobot project works with the SO-101, a 3D-printable arm. At launch, TechCrunch reported it started at about $100 (TechCrunch). The design files are on GitHub. You can teach it a task by demonstration and train a small policy, the same basic loop the big labs use.
If you want to watch and learn first:
- BattleBots on YouTube for the fights, including the free Pro League.
- Boston Dynamics on YouTube to see legged robots straight from the source.
- Russ Tedrake's free MIT course notes, Underactuated Robotics, when you're ready for the math of walking.
FAQ
Are BattleBots controlled by AI? Almost all combat robots are driven by a human with a radio. The 2026 BattleBots Pro League includes Orbitron, which BattleBots bills as the world's first AI-controlled robot.
How much does it cost to start combat robotics? NHRL says a capable 3 lb bot can be built for around $400. The SSP 2.0 beginner kit was listed at $450 on October 31, 2026, plus a charger and radio.
What's the cheapest robot dog or humanoid you can buy? As of October 31, 2026, Unitree's store lists the Go2 Air robot dog from $1,600 and the G1 humanoid at $13,500, both before shipping.
How do robots learn to walk? Many now train in simulation first, with thousands of virtual copies practicing in parallel, and then transfer what they learned to the real robot. This is called sim-to-real.
What I'm still figuring out
I don't know yet whether humanoids will be in homes in five years or twenty, and I haven't found anyone who can answer that honestly. What I do know is that the distance from watching a spinner on TV to understanding how a robot dog keeps its balance is shorter than it looks.
If you're starting from the same place, I'd love to learn alongside you. And if I got something wrong here, tell me.
Last updated October 31, 2026. Prices are list prices on the date shown and change often.
— Nate