I'm motorizing a pole/round tube to rotate clockwise and counterclockwise to a limit switch. It will not be able to rotate the shaft more than 360 degrees. This could be done with relays, limit switches and a foot pedal to control it. This leaves me to use dc gear motors that have a lot of backlash. That is one reason I would like to use an arduino is so I can run a nema 17 stepper and my own gearing. I would also like to add features in the future to allow for an auto scanning feature and following another shaft if possible. Is it possible to control the rpm's with a potentiometer? Just so the speed can be adjusted on the fly when no pc is connected.
This will be used in a marine environment so It will end up in a sealed box of some sorts and under the deck. What board would work well for this? I have a little experience with arduino from 3D printers but still a noob. Any help you can provide would be appreciated.
Ok, why can't you use DC gear motors with less backlash?
You can make or procure your own gearing and it will have less backlash? Then why not use that with a DC motor?
You seem to be implying that if/because you use a stepper motor instead of a DC motor, backlash won't be a problem. Maybe it won't, but won't that be because of the gearing, rather than the type of motor?
Do you need to be able to accurately and repeatably rotate this tube to some arbitrary but precise angle? That's the reason you would use a stepper motor. If not, the downsides of using a stepper motor will outweigh the upsides. In this case I don't get what that upside is.
Compared to DC motors, stepper motors are bulky, slow, expensive, complex to drive and very inefficient. They are brilliant for 3D printers, CNC routers, inkjet printers, but are they the right type of motor for your application?
Some of the products that are sold for this purpose seem to have an issue with backlash. I guess it's because they use cheap dc gear motors from amazon. One product that starts at $699 uses the motor in the screenshot below. Where do you recommend I purchase a good dc motor from? It doesn't need to have two vertical shafts an can be round.
I don't know what the backlash is on these motors. Just know it's an issue. Lets say it is 1 to 2 degrees. For easier understanding lets say I have a flashlight attached to this pole. I rotate the pole to make things in the dark visible. The cone angle of the flashlight is 20 degrees. At 100 feet it's 35 feet wide. 2 degrees would cause me to miss about 2 feet of viewing. At closer distances like 20 feet it shouldn't be as much of an issue but I would prefer it be as accurate as possible within reason.
If I did use a dc motor instead of a stepper what is my options for powering the motor?
You should specify:
- the size of your motor
- the torque on the outputting shaft needed to make it work reliably
- the maximum rpm on the outputshaft
- your budget. What amount of money would be OK for you to get
maybe you can't specify this in numbers.
Then it is even more important that:
You should post some pictures or a pretty detailed description of what this whole thing is.
With this informations it will be much easier to suggest a suitable solution.
best regards Stefan
If the device is sealed. Does this mean it is completely sealed and must work on battery?
If yes for how long does it have to work on battery?
I guess that regarding the environment
- salty air
- high humidity
- water splashing around
All microcontrollers are more or less the same:
sensitive to high humidity and water
you have to protect them against it.
I don't have any recommendations for you.
I agree you need a high level of precision. But....
Exactly! You don't tell the mechanism "turn to 37.25 degrees because there's something at that angle I want to see". You don't know what the angle should be, in advance, certainly not to the level of precision needed. You say "turn left", "stop", "a little more", "slightly back" until you can see that you have illuminated the object. Then, maybe you could read off that exact angle if you wanted. But even if you could, would there be any point? Would the fish or whatever always be at that exact angle, any time you want to go back and look at it again? If so, then a stepper motor would be ideal. If not, then a stepper motor has no advantage and a DC motor is better.
If you want to be able to tell an astronomical telescope "show me the M27 nebula", then stepper motors are the best way to move the scope because M27 will always be at a precise, predictable position in the sky.
It will run off of the boats starting battery. It will be accessible but not have ventilation. It will be used in freshwater and not directly exposed to water.
Motors used in this application are typically 3 to 12 rpm. The screenshot I shared above is the exact motor a few of the manufacturers use. I would prefer to stay under $50 for the first one until I can build the first one and test it.
At some point I would like to have the unit stay focused on a specific point. I'm not sure but I would think I would need to know the angle the motor is at? I would like to design it with my future goals in minds so that I don't have to start over. Or at least use as much of the first one I build as possible.
The picture isn't mine it just showed a good angle of the mount. It is just a tube that rotates inside of another tube with a dc motor on top. It then mounts to the side of the boat or a trolling motor. There is a ton of these and they get pretty costly for what they are. They prevent you from rotating more than 360 degrees to stop the cable from binding. At some point it would be great if I could add a feature to allow it to follow the direction the trolling motor is pointing. I didn't think that or staying locked onto a certain direction would be possible without something like an arduino.
OK now there is a picture.
Never seen such a device before. I have some assumings how it might work. But assumings are a very bad basis for going on.
I'm sorry to say that: If you want me to give further advice you will have to explain this device in much more detail.
What is a "trolling motor???"
You should make additions to this picture
what part exactly is the
You should give these two tubes unique names
My suggestion
the outer tube
the inner tube
what exactly does it mean if the DC-motor is
Again no idea if this DC-motor is on the inner tube or the outer tube.
Remember: I have never seen such a device before
What exactly is the "scanner?"
Is it a camera?
or
something else?
Is this an outboard motor with something additional that is scanning?
What is it scanning?
The alternative to descxribing the real device is to describe with much more precision what you want the device to do
best regards Stefan
- 40Kgcm stepper with encoder
- Stepper motor driver
- Arduino UNO
- Limit switch
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