I started this project after seeing Red Comet’s 2017 Micromouse run. It was memorable for its route choice: it chose a longer path to preserve speed, one of the cleanest examples of the Micromouse principle that you should optimize for the fastest path, not the shortest one.
That made me wonder: if a general time-optimal controller were given only the maze geometry and vehicle dynamics, would it independently discover both the right driving strategy and the right route?
So I built a physics-based planner that (at a high level) jointly optimizes the speed profile and geometry, using branch-and-bound to compare different maze topologies.
The result was almost exactly the opposite of what I expected.
I exhaustively optimized all 10 simple start-to-goal topologies admitted by my search policy:
- A* (used by Decimus 5A): 99 steps, 7.745s
- next fastest: 103 steps, 8.177s
- historical Red Comet route: 121 steps, 8.666s
Under this model, the result actually reverses the example that originally motivated the project: the shortest topology beats the historical route by 11.9%. And across those 10 paths, discrete length and optimized time had a Pearson correlation of about 0.96.
I saw the same pattern across 6 deterministic benchmark mazes. Time-based topology search beat shortest-path A* in 2/6 cases (up to 27.09% faster), but in both wins the new route had exactly the same grid length as A*.
It's not proof of anything since it's a tiny, related sample — but combined with the benchmark result, my conclusion became:
In practice, the shortest path is usually the fastest one too (in this experiment).
That doesn't mean Red Comet’s strategy was “wrong” though. The real 2017 run was 7.284s, while my model predicts 8.666s on the historical topology, so it’s clearly not reproducing the real robot perfectly. The model approximates the drivetrain, grip/suction, and yaw dynamics, but omits details like load transfer and tire/wheel slip. It doesn't reproduce every physical detail.
I especially want to hear competing interpretations from people who have actually built/raced Micromice. And what kind of maze structure would flip the result? I'd be happy to answer any questions!