The 3Pi distance between drive wheel axle center line and line centering sensors is 26 mm. Was this distance optimized based on overall robot dimensions?
Was there a geometric theory in play here? If so, where can I find such information?
It sounds like you are talking about the distance from the wheel axes to the nearest reflectance sensors (the outermost sensors) on our 3pi+ robot control boards. The placement of those sensors was based on positioning them as wide on the robot as possible without expanding the dimensions of the board, which is designed to nicely fit inside the 9.7 cm (3.8″) diameter bumper skirt.
The remaining placement of the remaining three reflectance sensors was based on positioning them as far forward on the robot as possible.