I am working on designing and building a small (1 1/2 lbs), 2-wheeled, differential drive Arduino-controlled autonomous robot. I have most of the electronics figured out, but I am having trouble understanding how much torque the motors will actually need to move the robot. I am trying to use the calculations shown here and the related calculator tool to determine what speed and torque I will need. I will be using wheels 32mm in diameter and one of Pololu's High-Power Micro Metal Gearmotors. I performed the calculations for a robot weight of 2 lbs to be safe and found that the 50:1 HP Micro Metal Gearmotors (625 RPM, 15 oz-in) should theoretically work fine, moving the robot at 3.43 ft/s with an acceleration of around 29 ft/s^2 up a 5-degree incline.
However, I have not found an explanation for several things that I think would be very important to know when choosing drive motors. When the robot is not moving and the motors are turned on at full power, they should need to deliver their full stall torque. Based on the calculations, it seems that any amount of torque can get the robot moving, but the more torque, the faster the robot's acceleration. Is this true? Also, if the power source cannot supply the full stall current of the motors, will the robot not be able to start moving? In my case, I am powering the robot through a 7.2V (6S) 2200mAh NiMH battery pack that can provide around 2.6A continuously, and when it does that the voltage drops to less than 1V. Will this be able to power my motors? Once the robot reaches full speed and is no longer accelerating, theoretically the motors will not be providing any torque, but I do not think this is the case. Is it, and if so, how will I know how much torque they will be providing? Will the motors I chose have enough torque to move my robot?