This assumes no loss in bearings, joints, etc.
Additionally, it would be great if you can let me know how to calculate the torque needed for each stepper motors too!
You are starting from the wrong end of the design. You are building a moving vehicle. You gave the weight as 30 lbs. Now how fast do you want it to go? And how fast will it accelerate? From that you can compute the torque required to bring the vehicle from stop to maximum speed in the time you have given.Google "vehicle acceleration power" and see if the results give you the formulas you need.Since you have 4 motors, divide the needed torque by 4 and you have the required motor torque. This assumes no loss in bearings, joints, etc.Paul
Or rolling resistance. What surface will this be moving over?Hardwood floor has less rolling resistance than carpet which in turn has (much) less than a lawnI am not sure where the stepper motors are defined in your configuration. You appear to be using the DC motors to drive the wheels for propulsion.What do the stepper motors do?