How a humanoid robot works, one playground at a time

Marvin Bot is an open-source humanoid robot, a walking, two-armed machine about 1.41 m tall and 40 kg, that is being designed in the open so anyone can study, copy or improve it. This guide explains how it works, from its joints and motors to the AI that makes it walk, for a reader with school maths and physics and no robotics background.

1

What is a playground? One page on one topic, with sliders and a live picture. You change something (a battery size, a joint angle, a motor) and immediately see what happens, then read why. Each takes 20–40 minutes.

2

Where do I start? Meet the robot in 3-D first (playground 00), then follow the numbers from 01: each one builds on the ones before. Curious about one part? Click it on the robot below.

3

Stuck on a word? Dotted-underlined words link to the glossary, which explains every term in plain language.

Start with 00 · Marvin Bot in 3-D →

Where the project stands

Marvin Bot is in phase 1 of 7: it exists only as a computer model, tested in physics simulators, and no hardware has been built yet. Every number in this guide comes from the project repository as of 2026-10-29, or from a cited source. Where the two disagree, the page says so.

Height

1.41 m

Mass (with shells)

41.0 kg

Powered joints

27

Hands

2 × 8 servos

Actuators

23 motors + 4 servos

Battery

48 V · 630 Wh

Computer

Jetson AGX Orin

Parts cost

≈ $17.7k

The map

Click a part of the robot (left) or a box in the pipeline (right). For the real thing, in 3-D, open playground 00. The panel shows what that part does and which playgrounds explain it. The pipeline reads left to right: the robot is described once in a file, turned into models, trained in simulation, and finally built and run. The colours match the stages of the learning path below.

Pick a part

Click a body region or a pipeline box to see what it is and where to learn about it.

Suggested learning path

The playgrounds are numbered in the suggested order, from basics to advanced. Each stage builds on the ones before it, but every page names its own prerequisites, so you can also jump to whatever you are curious about.

How to use this guide

• Play first, then read. Each page opens with a short idea and a playground. Try the presets, then the “Try this” experiments, then read the explanation.
• Marvin Bot boxes (amber) give the robot’s real numbers, with the repository file they come from. Violet boxes mark places where a published source and the repository disagree.
• Decision notes. Every playground writes a short note from your settings. Copy it into an issue, a design discussion or an AI-assistant session to take the idea further.
• Words you don’t know are underlined with dots and link to the glossary. Every source is credited on its page and collected on the sources page.