How to read this book

What a chapter contains, what runs where in the page, and how the numbers are kept honest.

ROS via Rust teaches robotics by starting from a problem a robot actually has. One robot carries the whole book: a TurtleBot3 Burger, a differential-drive base with wheel encoders, an IMU and a 360° lidar. The repository this book belongs to builds the software that robot needs, in Rust, one problem at a time. Each chapter picks a problem the repository has solved, states it as a number a run can produce, derives the theory the problem needs and nothing more, and then shows the Rust that solves it.

Three passes over every chapter

Each chapter makes the same three passes, in this order, and you can read it any of the three ways.

Foundation is the mathematics: definitions, results, derivations. Long algebra sits in collapsed blocks. The text states the result before the proof, so you can skip a proof and keep the thread.
Conceptual is the widgets. Each one makes a single idea visible and names, in its header, the misconception it exists to kill. Drag the first slider first: it is the one the caption is about.
Practical is the code. Every listing is a literal excerpt of a file in the repository, with its path as the title, so you can open the file and read the rest.

The widgets run the repository's Rust

Nothing on these pages is a JavaScript re-implementation of an algorithm. The pure crates of the repository (robotics_core, robotics_models, robotics_filters, robotics_sim, robotics_mapping, robotics_localization, robotics_slam) are compiled to WebAssembly, and every widget calls that module. A widget's numbers are the robot's numbers: the same exact arc, the same Joseph-form update, the same ray caster. The page only holds the sliders and draws what comes back.

Every stochastic widget is seeded and shows its seed. Re-roll steps to another reproducible run; re-roll 0 is the one the text describes. If something looks odd, the seed is how someone else sees exactly what you saw.

The color code

The same five colors mean the same five things in every figure, equation and widget, and the book never uses them for decoration: prior, prediction, measurement, posterior, and ground truth, which is always a gray dashed line. Symbols are fixed book-wide on the notation page.

How the numbers are kept honest

A number in a chapter is one of three things: a result a widget computes in front of you; a result of the repository's own recorded runs, quoted with the file it comes from; or a worked example pinned by a Rust test. The last two are asserted by the book's build: npm run check evaluates the compiled module against closed-form results and against the numbers the chapters quote, and fails the deployment if any disagree.

One caution applies to every seeded simulation. The repository's recorded runs are native, and the random generator behind a seed is a different one in WebAssembly (it is 32-bit), so a seed names different noise on the page than on the robot. A chapter says which kind of number it quotes: recorded numbers are native and are asserted by cargo test in crates/robotics_wasm; the numbers a widget shows are the page's own draw, and the build pins those too. Where the repository's own documentation records a limitation, the chapter says so.

What is here, and what is not yet

This book is written incrementally, one chapter at a time. A topic gets a chapter only after its work has closed in the repository: its code finished, its numbers measured, its documentation written and committed. The home page lists the published chapters; a topic that is finished in the repository but not yet written up here is listed as planned and is not linked.

Today six chapters are written:

Localization has one chapter, on the Extended Kalman filter; its Monte Carlo half, though closed in the repository, is not yet written up here. Planning, control, exploration and the complete autonomy stack are planned. None of those has a chapter, not even a draft, because a chapter written while its experiments are still running would quote numbers that are not final.