| The bar I set | Where I landed | |
|---|---|---|
| Working autonomous robot, demonstrated on camera | Follows on GPS, four-mode state machine, demo filmed | ✓ Hit |
| Under 20 hours of active build time | ~18 hours | ✓ Hit |
| ~$180 in parts (initial estimate) | ~$400 with tax | Revised |
What Was Built
An autonomous robotic vehicle built from off-the-shelf parts. It tracks the operator's phone via GPS, steers with a phase-based control algorithm, and runs a four-mode state machine — Follow, Manual, Park, Neutral. The phone needs no app; a standard browser handles everything.
Why It Was Built
Could a complete beginner take a physical-robot idea to a working prototype on a fixed time and dollar budget, using AI as the expert guide? The original underwater sand-burrowing concept was ruled out as too ambitious — the wagon was the right first project: meaningful, achievable, and demonstrable on camera.
Starting Competence
Zero robotics, zero electronics, zero programming, zero multimeter use — every technical domain was new. The one relevant prior skill was structured planning and a willingness to be uncomfortable.
How AI Was Used
Eight hours of design review came before anything was bought — killing four failed tracking approaches (AirTag UWB, Bluetooth RSSI, direct UWB, native iOS app) on paper before a dollar was spent. During the build, AI worked as an expert on call: a screenshot of an unfamiliar error returned a diagnosis and a fix in minutes, over SSH from the field. The Follow-mode controller went through three full rewrites and roughly six outdoor tuning rounds, landing on a phase-based algorithm that drives straight, executes a time-locked arc, then resumes straight.
Timeline & Conditions
About one month of weekend sessions, ~18 hours of active build time. No external deadline — self-imposed success criteria. Prior design decisions were captured in handoff summaries so each re-entry was fast.
Outcome & Evidence
A complete, working autonomous robot. It follows the operator's phone via GPS, runs a four-mode state machine with failsafes, is controlled entirely from a phone browser, and was delivered within the time target. The demo video shows it tracking across open ground, turning, and stopping at the set distance.
Key Metrics
LewanSoul/Hiwonder tank chassis · Raspberry Pi 4 · phone GPS via browser Geolocation API → Flask on the Pi over WiFi · four operating modes · 10 Hz control loop · phase-based controller (3 rewrites, ~6 tuning rounds) · 4 tracking methods rejected · 1 motor failure (warranty replaced) · ~18 active hours.
Lessons Learned
The first eight hours — the design phase — held the most leverage in the whole project. AI as an expert on call compressed days of forum research into hours, but the hardware work was still hands-on. Hardware fails, and that's normal: isolate, document, decide, continue. Every deferred feature was a deliberate scope decision, not a failure.
