[patrickrd]

Regarding stability (propensity for robot to tip over), you should see no increased tipping in cases where there is no lateral (sideways) acceleration.

You can think of this geometrically by drawing lines between your three wheels (a triangle). Next, draw an arrow in the opposite direction as you would like the robot will accelerate. You will see in the forward and backwards direction the arrow can be equally long before it exits the triangle (and thus it can accelerate in these directions with equal magnitudes before it begins to tip). But once you also have a lateral component of acceleration, there are directions where the arrow cannot be the same length. For these shortened vectors (again indicating acceleration in the opposite direction), you cannot accelerate as quickly before your robot tips.

Practically, this means that whenever you are making purely longitudinal (forwards or backwards) accelerations, you will not see any difference in how fast you can go before you tip. However, when you are making lateral accelerations as well (such as turning while simultaneously moving forward or backwards), you will lose stability in certain directions.

Further, I noticed you want to put the driven/powered wheels in the front. Keep in mind that when you accelerate in the forward direction, you are simultaneously taking weight off the front wheels, thus reducing your traction. It would make sense to put your powered wheels on: (a) the heavier side of the robot, and (b) the "rear" side behind the direction you will most often accelerate.

Hope this helps.