More pBasic Woes...

[Dan 550]

Well, frankly, I need some help. Since I despise tank drive (I don't like its tendancy to make the bot hop up and down and jitter and stuff.), I decided to engineer a nice, simple four-wheel steering system, much like Delphi Automotive has engineered recently for use on GM's large trucks, to reduce the turning radius of the trucks to about the radius of a compact car. Now, the diagram (Below; excuse the crudeness of the drawing please, I'm no artist, and all I have on this PC is Paint. By the way, it's not to scale at all.) I've included is basically the setup I want to go with, due to its mechanical simplicity, using only rack, van door motors (not pictured), pinion gears (blue circles), bearings, and drive motor assemblies (red boxes). The larger bearings (pink circles) are fixed in place, while the smaller (green circles) are attached to sliders (not pictured) and to the rack.
I have the mechanicals squared away here, but I have a bit of a problem with a bit of code I want to include to 'accident-proof' the robot. You see, I do not want a driver to have the ability to accidently leave the wheels in a turning angle when he should be going straight. I would like to put something in the code that the robot controller interprets as 'when x-axis = 0, return steering boxes to forward'.
Is it possible to define a zero point on the rack and make the motors turn the wheels so the point aligns zero rack with zero forward, automatically? Would this require use of the light sensors as well? This would really help prevent an escapade such as getting off the bridge while not at the bottom of it. (I did that once, and busted the dead axles on our rookie-year bot.)
http://us.f1.yahoofs.com/users/77b4b...eWRO8AdCukPBSH