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Unread 10-04-2013, 08:15
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Re: Question about encoders to control motor

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Originally Posted by gluxon View Post
Either way, that code is stopping and starting the motor at what I would guess to be a very high rate. I'd imagine some mechanical stress depending on the motor used, no?
You are already bang-bang controlling the motor anyway. That's how pulse width modulation works.

If your bang-bang controller is running fast enough and your sensor input is sufficiently noisy (enough to cause many on-off transitions), then the bang-bang control method is no different on the motor than running it by PWM.
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Unread 10-04-2013, 10:26
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Re: Question about encoders to control motor

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Originally Posted by Chris Hibner View Post
You are already bang-bang controlling the motor anyway. That's how pulse width modulation works.
That's not strictly true. If the motor accepts a PWM signal directly, then in some cases you may control it that way, but the speed controller is what receives your pwm signal, and it adjusts the voltage out in proportion to the PWM duty cycle, the motor never sees the pwm on-off cycles.
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Unread 10-04-2013, 10:36
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Re: Question about encoders to control motor

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Originally Posted by DjScribbles View Post
That's not strictly true. If the motor accepts a PWM signal directly, then in some cases you may control it that way, but the speed controller is what receives your pwm signal, and it adjusts the voltage out in proportion to the PWM duty cycle, the motor never sees the pwm on-off cycles.
The motor controller receives PWM as an input signal, and it outputs a PWM voltage to the motor. That's how it adjusts the output voltage... by Pulse-Width-Modulating the 12-volt battery power.

But there is a sense in which you're right. The input PWM period (for the Jag) is 5ms (200Hz). The output PWM frequency (for the Jag) is 15,000Hz. 15,000Hz is fast enough that the inductance of the motor (for a CIM anyway) smooths out the current so there's very little ripple.



Last edited by Ether : 10-04-2013 at 10:48.
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