Hi folks,
After looking into and pricing some powerwheels for kids (ride on toys), I figured I could do a better job myself.
I designed a small skid steer I’d like to build…but I have a few questions.
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Powerwheels use 35w geared motors, so I figure 2, 100 watt motors @24v would be ample power (correct?).
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I believe I would need to hook the motors (on on each side) to a speed controller, but I’m not sure if they would need to be geared if I have the speed controller. I calculated about 400rpm would be ample speed for my kid, but keep finding motors at 2500rpm, or worm drives at 100rpm… need suggestions.
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Would I need a speed controller for each motor as the motors will have to run forward/backward independently?
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Finally, as it’s a skid steer, i would have two joystick controllers to independently control the forward/backward to turn the unit. What I’m uncertain about is how to incorporate a speed control with in that set up… perhaps I just set and forget the speed, which is typical in a skid steer/bobcat.
Any help would be appreciated to avoid costly mistakes.
Hello there!
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Not every motor is made equal. A 100 watt motor from brand A may have a 8000 RPM rate but a low torque and another from brand B may have a very high torque for only 100 rpm. We have a good tool to calculate the torque and rpm needed for motors: https://community.robotshop.com/tutorials/show/drive-motor-sizing-tool
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A gearbox will either reduce the RPM of the motor to increase it’s torque or reduce the torque to increase the speed. A 100:1 ratio gearbox reduces the rpm 100x but also increases the torque 100x. Please refer to the guide above to know the torque and gearbox needed.
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There are motor controller with 2 or more channels so it would be possible to hook up both motors on the same driver. See the link in answer 4 for an example.
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You could control the vehicle with just one joystick if you’d like. For example, if you push the joystick to the left, make the left track go backwards and the right track go forwards. If you push the joystick to the upper left corner, make the right track go at full speed and the left track go at half speed. If you’re not comfortable with programming, it might not be the best option. If you want to keep it simple, a driver like the https://www.robotshop.com/en/sabertooth-dual-motor-driver.html?product-code=RB-Dim-44 can be controlled with 2 0v to 5v inputs. Please note that this driver might not be suited to drive your motors, always make sure that the peak current of your motors do no exceed the specifications of the driver.
Please contact me if you have any other question.
Cheers!
