Working on a project and need some help please. Trying to measure the current load on an auger system that has restriction fingers that move inside the tube ( from the outside) to maintain a tight feed through the auger.. Think of a jet thruster.. The auger motor is a 240vac motor. I was looking at using a hawkeye 921 current sensor and a large nema stepper motor or servo. To push against a piviot point to change the fingers position. It needs to be able to adjust the stepper positon and direction to Change the position of said restricton fingers to increase or decrease motor load.. Also would like to be able to data log the current sensing on an LCD screen and adjust the fingers manually if needed. Having never written an arduino code before I'm kinda lost for compiling a working library to perform this task.. Any help or guidance on this project would be much appreciated as I'm sure for someone with more experience in arduino this is probably a simple task... Thank you much in advance.. We have the mechanical portion ready for the controls system.
The hawkeye 921 provides a 4-20mA output with fullscale input switchable between 10,60 or 90 amps. At 240vac that's a beefy motor - several horsepower - and a stepper to do that would be a very expensive device.
But you say you've got the mechanics sorted.
Interfacing the hawkeye to an arduino is relatively straighforward - see the enclosed.
Allan
420.pdf (17.5 KB)
Thanks Allan, I will use that schematic... Being new to writing code for the arduino to use, where do you recommend I research on how to make the code? for example turn the stepper one way if current decreases or turn the other way if it increases... Need the current probe to be the input and the stepper movement to adjust the load accordingly.
A stepper motor is normally driven by dc pulses. The device you have will have drivers associated with it - look there.
But you mention monitoring ac current.....
I don't understand.
Just what sort of motor do you have?
Allan
Yea I need the arduino to monitor the current from the 240vac drive motor for the auger and control a stepper motor driver as an output which will adjust the resistance on the material flowing around the auger shaft... At the end of the shaft is a group of levers that protrude into the media and create a restriction.. Those levers are adjustable to an almost free flow or a tight restriction. A linear movement outside the shaft changes the position of these levers inside the shaft ( they pivot right outside the tube and protrude into the shaft) say a counter clockwise rotation of the stepper will increase the tube restriction and vice versa.. Need to try and maintain a constant current on the auger drive motor via restriction control... Let me know if it still don't make since and I will try and draw something up... Biggest question is how to make the arduino change an output based on an input signal.. I have used them before on my 3d printer and milling machine. I can modify a code but have never written one from scratch.. Where do you guys go to learn to do that? Kinda like making the 3d printer turn on the heater when a lower temp is detected and off when its too hot...
OK - I've got the idea.
You measure the current of the ac motor as we've discussed, and use a stepper motor to wind a restriction in and out .
It isn't a big problem, but if you've never written any code before, it's time to start!
I take it you've downloaded the IDE.
Fire it up, and open the 'examples' menu under the file menu.
Do you have an arduino?
If so connect it via a USB cable.
Try compiling and downloading some simple 'sketches' - ( the weird arduino name for a program.) Start with blinking a led..
It's learning time.
Play for a while and get back -stepper motors aren't that bad, and there are libraries to help.
Allan
Yes! Thank you very much Allan. I have the pieces and have modified code in ide before however this portion of it is like performing a round trip to the moon to me. Ive played with the example sketches a little but how to make one from scratch is beyond my knowledge.. Guess I just gotta spend more time in ide and get to know the ship a little better... Thank you for you're help and the quick responses!
What you want to do is called closed loop control. This is easy to do with Arduino since there are libraries (pre-written code) that perform the thorny parts of control, primarily the PID loop. Google it. But, please don't get lost in the math on Wikipedia, look for some simpler explanations like this one:
http://www.pc-control.co.uk/feedback_control.htm
The Hawkeye is the feedback element, the stepper motor receives the controller output.
Sweet thanks! Still trying to learn this programing thing.. How to make output 1 respond correctly to input 1.. You know what I mean.. How does one learn to build a library to suit individual project needs.. Sorry just never gone that far into it.. Do you typically modify a library or sketch to suit you're need or write one from scratch? I understand the function of say a closed loop ecm in a car but how to make a new program to make the components do what needs done is news to me... Any direction or guidance will be much appreciated and used for life on. Feel like I need to go back to school to program an arduino with a one of a kind sketch...