The Robot Moves!
The robot has been wired up and some rudimentary code written. It moves. The bumpers are all wired up as well and so it has collision detection.
The video shows the robot randomly moving around the workshop floor. It actually pushes all the debris on the floor to the edges of the area it covers, which is essentially what I hoped it would do. I swept the debris up with a dustpan after it stopped, which was easier than sweeping the whole floor.
Next step is to add a vacuum system so the robot collects debris rather than push it about.
Also, I'm not sure the cheap batteries I bought recently as battery packs are anywhere near the capacities they said they were. Hmm, not too much of a surprise bearing in mind the price.