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Controlling the speed of motors with a servo controller. 
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Joined: Thu Jun 11, 2015 8:00 pm
Posts: 1
Post Controlling the speed of motors with a servo controller.
I have a bit of a problem with my coding, and any help would be greatly appreciated.

I built a gocart for my school class, and we are using two FRC motors for the drive wheels. The robot is powered using the tetrix HCMotorControllers. We have a standard 12-V battery powering the whole thing. When there is no load on it, beyond the wheels themselves, the wheels work just fine. When there is the weight of the cart itself being moved, it moves quite fast. However, when we tried to ride on it, the battery blew its fuse. Twice.

I originally had the power at 100%, and I lowered the power levels down to 50%. The robot still moves, and it carried a light person a few feet, but the problem is that the power levels go from 0% to 50% without any delay, which is what caused the fuse to blow in the first place. I was thinking that I would be able to affix a servo to the cart, and use it as a power regulator, similar to a gearshift on a car. However, Ihave no idea how to make it work. I was thinking that I could assign the servo value a variable, and then set the motor power to that variable. However, there was no change in the speed of the wheels, even though the code compiled, and it seemed to work.

Is there a way to make this work? If not, is there a ramp up program that I could use to make the motors ramp up to speed? If anyone could help me, that would be great!

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Thu Jun 11, 2015 8:16 pm
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Joined: Sun Nov 15, 2009 5:46 am
Posts: 1523
Post Re: Controlling the speed of motors with a servo controller.
The Tetrix motor controller can't possibly drive an FRC CIM motor. You need to look at the specs of the CIM motor and the Tetrix motor controller. The amount of current the CIM motors draw can easily fry the Tetrix motor controller. You are lucky that the fuse was blown instead of frying the motor controller which could get expensive. None of the FTC components are strong enough to allow you to ride on. I don't understand what you meant by using a servo as a gearshift. But it is expected that when starting a motor, the inductive load will cause a current surge that will certainly blow the fuse or worse, fry the Tetrix motor controller. If you want to build something to ride on, stick with all FRC components.

Sat Jun 27, 2015 1:42 am
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