pic: Prototype Drivetrain v2

[LLogan]

Originally Posted by 548swimmer

We haven't had any issues with handling, but why not investagate this in the off season.

With springs tensioning the suspension, it will rock only as far as it needs to. Using a diff. eq. we can figure out the specs on the spring. Ideally, at rest, the spring keeps the wheels exactaly level. Once the robot starts moving and the CG "shifts" the springs will expand cushioning any sudden blow (like a rapid acceleration). Additionally, if this robot starts to get flipped, all wheels can stay on the ground providing some traction.The front ones would lift off the most, increasing the Fn on the rear and center


That still leaves the problem of chain runs though. I'm not sure a slot would have low enough friction, plus the exterior has to be smooth for the bumpers.

The bolded part does not entirely make sense for what you want to do. There is absolutely no point in keeping all the wheels exactly level if only the center ones are driven. Your rear wheels will not be driven, so it's quite useless to increase the normal force on them. In fact, it's detrimental because you're decreasing the normal force that is on the center wheels.

I am unsure of why you are so set on a suspension.

Originally Posted by Edoc'sil

Forget the suspension if you are not doing two things:

Driving over rough terrain like the bumps
Powering all wheels

The whole point of a suspension is to make sure that the normal force is distributed as evenly as possible. Doing this is only advantageous when each wheel is powered, seeing as your tractive force is based on the sum of the forces of friction and thus the normal forces.

My advice: a suspension is not worth the hassle (and relatively useless) unless you are powering all wheels, or going over a surface that is not flat. To compensate for the sudden stops and starts, perhaps you could try to scale the acceleration and turning to your discretion through programming.