reycreator17:
Hi again Thanks everyone. Yeah. I kinda realize that, it is the friction between the gears inside the motors is what stop the whole thing or we call it as static friction. I just dont know how to compute for it. For my robot, i want it pretty slow maybe 0.05 m/s - 0.1 m/s and the acceleration would be maybe 0.025 m/s^2 plus may slope of 20 degrees maximum. I want it to be able to carry 5 kg on it.
@MarkT about the power consumption, I was thinking of using this source since it has 4A max drawing power for 12V.
https://www.amazon.com/Intocircuit-26000mAh-Capacity-Portable-External/dp/B00BB5VQCE
And this stepper motor.
https://www.sparkfun.com/products/9238
Any suggestions if this is overkill or good enough Thanks
You aren't listening?
No to stepper,
First determine the mechnical requirements, then the gears and motor, then the motor driver, then you can
think about power source (the endurance depends on the pattern of use and actual losses, you haven't anyway to determine that yet.
that yet).
You have some figures: 20 degrees, 5kg (total mass?), 0.1m/s
So total force to wheels is sin(20) * 5 * 9.8 = 17N
power = 17 x 0.1 = 1.7W
total torque = 17 x 0.04 = 0.7Nm
Now allow a good factor of 2 for losses, and guess that 2 wheels are driven,
so thats 1.7W and 0.7Nm to each wheel at 25rpm.
A 100:1 gearbox for each motor would mean 2500rpm motors with 7mNm of torque.
Assume 3.4W mechanical from the motors, 5W electrical in, so for 5 hour endurance uphill all the
way thats 25Wh (2.2Ah for 12V supply, say). Note thats about 2km run with 600m of ascent!!!
For more modest use the average power would be correspondingly less.