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Author Topic: High Power PID Controller  (Read 1084 times)
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Hey guys, I was looking around and couldn't really find any PID controllers that were very high current/voltage.

I am building a 3-axis CNC machine and I want to be able to vary/regulate my router RPM. There is a product called Super PID which has a few videos on youtube and a website www.superpid.com. That is basically exactly what I am looking for except I don't wanna $155 on it. I have done PID control before but with 12V CPU fans and a 5V thermistor. So I was wondering what type of things do I have to consider when dealing with a 2-1/4HP 11Amp 220V router? I have a Hitachi m12vc, Currently it has a switch which regulates the rpm from 8000 RPM to 24,000 RPM. I'd like to be able to go down to 5000 RPM such as the SuperPID.

Also I was wondering what would be the best method for measuring the router RPM, I was thinking of using an optical sensor and a some white paint on the spindle head would work?

Okay well let me know if I missed anything, I am using a Arduino UNO with GRBL installed but i could use an external PID controller which I would set manually instead of via gcode.

Thanks
-Ryman
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I have the same router and found that it already has some form of electronic feedback for the speed control. If you remove the cover of the router you will find a module that sits over the shaft end. Removing this you will see a circular magnet on the shaft end which fits into a pocket in the module where the magnetic encoder is enclosed. It's been my intention to obtain another router so I can have a spare and then open up the module (it's hermetically sealed in what looks like silicone). Although hacking whatever chip is in there may be difficult, I imagine that the encoder signal could be used with an arduino to create an external PID controller. Take a look and see what you think.

The logic for such a controller is the easy part, I think. The more daunting task to me would be designing a safe and reliable power circuit.
« Last Edit: August 21, 2011, 01:13:17 pm by Yankee » Logged

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I have the same router and found that it already has some form of electronic feedback for the speed control. If you remove the cover of the router you will find a module that sits over the shaft end. Removing this you will see a circular magnet on the shaft end which fits into a pocket in the module where the magnetic encoder is enclosed. It's been my intention to obtain another router so I can have a spare and then open up the module (it's hermetically sealed in what looks like silicone). Although hacking whatever chip is in there may be difficult, I imagine that the encoder signal could be used with an arduino to create an external PID controller. Take a look and see what you think.

The logic for such a controller is the easy part, I think. The more daunting task to me would be designing a safe and reliable power circuit.

Yes, PID software is a pretty straight forward application function. The trick has always been to be able to get a reliable and accurate input variable (PV, process variable) and a accurate and reliable hardware output circuit able to control the final control element, The output variable, in this case a motor driver circuit.

 A decent GUI for user set-point adjustment and the ability to modify the 'PID tuning variables' is also nice but not nearly as difficult as designing and building the input and output interface circuitry.

Lefty
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Don't forget to check the PID library's in the playground

example
http://www.arduino.cc/playground/Code/PIDLibrary
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