Wiper Motor for automating outdoor blind

Hardware
1

I was hoping for some advice before I embark on this project.
I have an outdoor blind, 6 meters long, that has a manual lever that you turn to open or close it. It is a roller blind, so it rolls up on a big roller at the top, and it runs in a metal track that runs on each side. It also had a metal bar at the bottom.

I want to motorise this blind so I can lower it based on the sun elevation, then completely open once the sun has set.

I looked into different blind motors, but they all seem way too small to turn this mammoth blind. After someone mentioned it I started looking at geared motors, and looked at wormdrive. Which then led me to look at wiper motors, out of a car.

I have found one, they are fairly cheap ($50), and seem to have enough torque and RPM to do the job. They are also 12V DC, so running them should be fairly simple.

I need to be able to somehow reverse polarity to the motor, so I can open and close, and I also need to be able to work out where the blind currently is.

I am looking to drive this all from something like a Wemos D1 Mini over MQTT.

So what would be the best way to work out how far the blind is open?

My current thinking is something along the lines of making a home switch at fully open. And then perhaps use time to work out how far the blind have opened (10 seconds = 50% for instance), and then depending on how accurate that is, maybe add another home at fully closed? Then I can tell the Wemos on power up, home the blind (open fully) and then it will know where it is from then on.

Is there a better way of doing this? I thought of doing it with a stepper so I know where the motor is at by counting steps, but I don’t think it will have the torque.

I am planning on attaching the wiper motor to where the existing lever attaches, which already has some gearing, I crudely measured it and it seems it requires about 2.5NM to move it, the wiper motor is 5NM with 29NM overdrive.

Any advice or comments appreciated

2

if you google outdoor roller blind tubular motor you should find the proper motors that fit inside the end of the roller blind. Not sure where in the world you are but here in Aus they can be bought. sure, you can go the wiper motor but in my opinion it will be bulky and ugly. I’d spend the money for a hidden motor, then use HA to control it.

assuming you mean blinds like these

3

Thanks Sparkydave, I am in Aus.
Do you know if these are generic, or made specific to fit my blind?
Also do you know how people integrate these into HA?

4

I’m fairly sure you can get generic ones. I had what sounds like the same blinds at my old house and the top roller is a standard size to accept the tubular motors. You take the hand powered winder gearbox off the end of the roller and insert the motor. To control it you can use a zwave device like this, or your own NodeMCU & relay control via MQTT for example. Personally I would go with the zwave controller as it provides overload protection and proper feedback etc. See the manual for more info. If you dont already have any zwave gear then just be sure to get the AUS frequency devices (ie: not from the US) as they must comply with our frequency range. I use an Aeotec Z-stick as a controller and have had zero issues. Some people in the US have complained on here about them but in saying that, I moved to it from a Vera which ended up in the bin… the people that didnt like the Z-stick bought Vera’s… go figure

5

Thanks, for your advise. I have hit up another couple of companies to see what they can offer me.

6

You would need to check the exact details but this may be very similar to what you need

7

That looks much better than a wiper motor. Fairly cheap too, might pull the blind apart on the weekend and remove the gear like you said and see what is what. How did you get position feedback with the zwave controller, did you use the limit switches?

8

does the tube need to go the entire length of the blind?

9

I didn’t end up getting them as I sold the house. The unit learns the current curve of the motor based on the changing load as it winds up and down, allowing it to determine the blind position.

10

If you end up using a Wemos D1 Mini it might also make sense to place Reed switches at the top and the bottom to get an indication - and an emergency shut off - when the blinds are fully open or fully closed.

11

Yeah, i was thinking that would be a good idea to home it with. I am waiting on one or two people to get back to me re the tubular motors. Depending on the total cost i will go either that way or the wiper motor way.
The blind is outdoors and there are plenty of places to hide the motor, although it will be better if it i can be hidden obviously.
I will post back with what i ended up doing and if it worked or not.

12

So i just wanted to report back with what ended up happening with this.
Any blind motor was close to $1500 for the size blind i had, and this was outside my price range.

I also had a look inside the tube and there was no obvious way to mount any motor in there with the supplied brackets, so i decided to have a play with the wiper motor idea.

I ordered a H bridge for about $20, this was a BTS7960 which is 43A H Bridge, which would be plenty for me.
I managed to get a old wiper motor from a scrapyard for about $10.
i had a Wemos D1 clone which was about $6. and a level shifter which was cents.(for changing 3.3v to 5v)

I used a old computer PSU, wihch has a 12v rail on it, for driving the wiper motor, and also has 5volt standby power for the wemos. The nice thing about this is you can electronicly power on the PSU when needed, and when it is off, it only supplies 5v standby power. So I have my electronics running on the always on 5v standby power, and when the blind is required to move, i just turn on the Power supply while it is moving, and then turn it back off, saving power.

I found 2 Photo Electric sensors in a photocopier (a friend did) and they basically transmit IR on the one side, and then there is a photo sensitive resistor on the other side. They are in the shape of a small U, i guess. When the path between the 2 ends is not obstructed, it lets power through the resistor as the IR is hitting the resister, and when you block it, no power makes it through.

I then 3d printed a rotary encoder wheel that fit on the wiper motor shaft. The Rotary encoder has slits in it, and these slits pass through the photo electric sensor, and as it turns, it blocks and then doesn’t block the IR. This means i can count steps with 1, and with 2, i can count steps backwards and forwards, and i will always know my exact position, giving me kind of a stepper motor.

I then used a reed switch as suggested at the top, to home the blind in the event of a power failure.

So at power on, I wait 2 seconds, and then I turn on the computer power supply, i move the blind up, at minimum dutycycle (slow) until i hit the reed switch at the top, i then back of until the reed switch is no longer triggering, and then i set that as position 0 (Open). I then turn of the PSU.

I then report over mqtt that the blind is open and it’s position is 0. HA picks this up and shows it in the UI.
I counted the steps from completely open to closed, and it is 9998 steps, what a weird coincidence. So in the Arduino i map the Cover position in HA which is 0 … 100 to 0 … 9998 and when HA asks me to set the blind to position 50 for instance, the arduino knows it has to move to position 4999. It will turn on the PSU, soft start the blind, i also use some basic PID to move slow, if i am only moving a little bit, but move fast if I am moving a lot. The blind will move, it will slow down as it gets closer to it’s desired position. Then stop, turn of the PSU and report the position on mqtt.

This is also hooked up to google assistant and siri via HA, so it makes opening and closing the blind very easy.

I had some trouble with the blind behaving erratically. Basically going up by itself in the afternoon. After a bit of troubleshooting i worked out it is the sun (which also emits IR), that hits the photo electric sensor and causing it to misbehave, once i build a little box around the whole setup, it stopped.

I suppose it doesn’t look as clean as what a tubular motor would have looked, but the project was alot of fun, and I was amazed by what you can accomplish with a few cheap parts and a bit of junk that you have laying around at home.

The ultimate goal is to have the blind use the Angle of the sun to auto close, which is now very easy to set up with a few automation’s.

1 Like
13

Pics or it didn’t happen :wink:

No, really - it sounds like a great project. Lots of fun, I bet.
And: honestly - do you have some pics you can share? Including the UI?
Would be great!

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Be kind, the welded frame and it’s cover (not in pics) is a work in progress. And as you can see I am not a welder.

1 Like
15

Veeery nice - thanks!
And all that for less that $50 :+1:

Like the slider in the UI, great idea!

1 Like
16

Nice work mate.

1 Like