Last night I built a pair of improved wiring harnesses so I could connect two motors to the Arduino. Once concern I have is that the control logic that manages the acceleration and deceleration could be so slow that it will interfere with the motor drive signaling when trying to control more than one motor. I have in mind to replace the floating point logic with a lookup table, but for now I like being able to easily fiddle with the motion parameters.

It turns out that two motors work pretty well with only minor tweaks to the existing code.