A mower that mows until the battery dies in the middle of the lawn isn't a product. This milestone gave the simulated mower a battery that drains by what it's actually doing, a dock with charging contacts, and a mission that goes home when it must, charges, and comes back to exactly where it stopped. It took three runs, and the two failures were both about the last few centimetres.
Phase 4 is the one Chris was waiting for: the robot plans a mowing pattern for a lawn and mows it. A planner turns the lawn (a GeoJSON polygon with keep-outs) into a path, a follower drives it on the RTK pose, and a report says, with ground truth, what got cut and whether anything went wrong. The first run finished the lawn. It also drove into the flowerbed 24 times. This post is about the four fixes between that run and a clean one, and about the tool that made the last fixes take seconds instead of minutes.
Chris's rule for this phase: "Before we build something in code, maybe it should have new telemetry?" So before the first ROS node existed, we wrote down the questions we'd ask of its data.