Stepper Motor and Driver

@zander Ron, My wife's uncle passed out while driving 80mph on the expressway.  Luckily his wife was able to steer the car and get him to come back to his senses.  He received a pace maker a couple weeks later and it has been a significant change.  More energy, better focus, etc.

Good luck!

@zander

Posted by: @zander

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They and many others sell UHMW plastic

I'll look into it.  I like the idea of using this as the edge guides.

Posted by: @zander

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Ok, I promise to stop now.

LOL, no need to stop.  I really appreciate all the advice/recommendations.  

Thinking about the requirements for this project I realized I forgot one important capability - solar powered.  I need to check the voltage range of the stepper motor.  I currently have two solar panels.  One is from Waveshare  (6V 5W) and the other is a 5V 2A solar panel.  I also have a Waveshare Solar Power Management Module with onboard batter charging.  Not sure if I need to get smaller stepper motors like those that come in the Arduino kits.

Mike

@zander

BTW, this discussion is being printed and placed in a file folder for this project.  Thanks again.

@huckohio I built a 7,200wH battery bank, 1,080W solar panels (57V 20A) so I am familiar.

What you need to do is some calcuations. Use WATTS, that way you don;t need to switch back and forth. Use 4 hrs at some percentage for total power from those two panels. I NEVER got 1,080Watts, unless you spend power to constantlyaligh them NS daily, and EW by the minute. Where I live the sun rises and sets in the NORTH. I used to watch the sunset from my couch in my lakeside home that was built on the compass, the lakesdie windows were facing due north. I have an excellent web site that will demonstrate the concept, it is at https://www.suncalc.org/#/49.3353,-124.4692,19/2017.09.16/13:12/5/2

Myhunch is those two panels together wil harvest. Even if they are 100% efficient, the experts tell me 4 hrs a day is the number they use but the following site will tell you exactly https://pvwatts.nrel.gov . If you have questions about any of the information you need to enter, just post or PM me.

So using rough calcs, 60WH is 12AH at 5V. If usage is average over 24 hrs, that is 500mA each hour but if you have 12 hrs of inactivity, then you have a power budget of 1A per hour. Check the specs of the stepper. Will you be raising and closing it multiple times, my friends with chickens only do that once a day. so 500mA up and 500mA down. Sounds doable, but if noty just scale up the solar panels.

Once that is done, now you have to add multipliers for clouds and rain. That means if those two are ok, then buy 3 more sets.

Hi @huckohio,

  Whilst stepper motors quote a small voltage, say 4V, they are rarely connected to such a low voltage. The problem is that as soon as they start to move, they generate a back voltage that opposes the supply voltage. It is the job of the driver to control the current going into the motor. Perhaps the first issue will be the driver board's voltage requirements.

Sorry, there are always complications and problems!

Best wishes, Dave

@zander 

Posted by: @zander

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What you need to do is some calculations. Use WATTS, that way you don;t need to switch back and forth. Use 4 hrs at some percentage for total power from those two panels. I NEVER got 1,080Watts, unless you spend power to constantly align them NS daily, and EW by the minute.

Ron, Take a deep breath and count to ten before you read this question... 😀  

Couldn't I just buy one of these versus doing all those calculations (Link or Link)?

@huckohio Those are indeed very handy units, if you are not going to do the math, get the ubit with the biggest battery (5200mAh) and see if it works, if not buy a second and keep adding until you have enough power. Keep them all the same, I would go with the 5W (2nd link) and wire the outputs in parallel. 

Posted by: @huckohio

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While it's in the high 90s outside I though I would look at replacing the automatic door on the chicken coop.  I watched Bill's video's on stepper motors and drivers and I think I picked out units that would work.  I would like confirmation that I selected a proper stepper motor (i have no specs on door weight, travel length, etc.).  This is my first time working with a stepper motor.

The vision would be to integrate this with the existing ESP32-S3 system already in the coop.  The ESP32-S3 would talk to the A4988 H-Bridge motor driver.  

For the stepper I've selected a Nema 17 Stepper Motor 42-34 3D Printer Motor DC 1A-3.4V 2 Phase 4 Wires 1.8 Degrees (Stepper Motor).

Since there are so many variations of the Nema17 I would confirmation this unit would work or maybe a suggestion on a better option.

Thanks

Mike

This motor should work fine if you gear it so the motor torque is adequate for the job. Timing belts and pulleys or a lead screw are good options. Use a voltage near the limit of the A4988 (35V) to get the highest RPM. Note that the 3.4 volt motor voltage is the minimum voltage that will produce 1A in the motor. There are other stepper drivers available that might be easier to select the desired 1A motor current. It appears the A4988 uses a sense resistor to detect motor current while some others use switch settings to determine current. Limit switches are also a good idea in case the motor misses a few steps and loses track of where the closed and open positions are. I would use the closed limit switch to reset a home position and input the number of steps you think are required to open the door. Or just run the motor until it hits the open limit switch. As others have said, a "chicken sensor" of some type would be a good idea to stop motion, much like those used on garage doors.

Bob

@bbutcher85 @huckohio Pololu is a good resource.