Motorized Stroller Swinger

Intro: Motorized Stroller Swinger

In this instructable I'll show you how I made a portable, motorized stroller rocker / cradle swinger. It can easily fit lots of different types of strollers and cradles, so you can use one setup for multiple baby accessories.

Why make a motorized stroller rocker? Well, my elder brother and his wife had the first grandson of the family. When the dust settled, it turns out that being a parent is tiring. Apparently, babies don't sleep that well, and one of the things that helped his baby boy fall asleep was swinging his stroller back and forth. He said that they're swinging the stroller about 5 (!!) hours a day, so this problem had to be solved. They tried to buy a motorized stroller swinger online, but couldn't find a decent solution. He wanted something portable so he could use it at different spots around the house. It took a really long time to make working prototype (you can see my failed attempts at the bottom), find the right engine, and shipments from china took a really long time. So by the time it was ready, he didn't need the stroller rocker for his baby boy anymore... But then, he told me they're having a baby girl. So, long overdue, I made this motorized stroller rocker.

STEP 1: Prepare the Housing

Start by turning a box into the base of the product. Eventually, the motor controller will be placed inside the box, and the motor will be on top of the box.

• Cut a slit for the on/off switch (1st image).
• Drill holes for the suction cups to be screwed through (2nd image).
• Add holes for ventilation (3rd image).
• Add another hole connecting the inside of the box to the top part for wires going from the controller to the motor.
• Finally, drill a hole in the back of the box for the power supply to go through.

STEP 2: Attach Suction Cups

Screw the suction cups into their holes and lock them in place with bolts.

Tip - the suction cups are okay, but they don't hold the floor for too long too well. To fix that, just put some water on the floor before attaching to the floor. Future versions will have a strong suction cup.

STEP 3: Prepare the Arm

We need an arm to hold the stroller. I use a huge clamp which I took from an old jumper cable. Attach the clamp to one end of the metal rod. I also added some packing foam from an amazon package to make the clamp's grip better. To the other end of the rod, attach some sort of a connector. This connector will later be attached to the rotating piece that's connected to to the motor (see steps 4 & 7).

STEP 4: Attach Bearings (and Baby-proofing)

We now need to make the part that will be attached to the motor on one side and to the swinging arm on the other (take a look at step 9 or the intro video to see what it looks like). The swinging arm should have freedom to rotate, so you'll need to attach some kind of a bearing here. I used a ball bearing. The 'connector' side of the arm will be attached to this bearing soon.

Attach the bearing to this piece (the disc in my case, or some other object in yours). To connect the bearing to the rotating disc I 3D printed an adapter and glued everything with superglue. You'll most likely be using a different part instead of the odd disc I used, so I didn't include the STL files (but if you want it - let me know).

I tried to make sure everything is baby-proof and so there are no holes in the rotating disc. I covered the remaining holes with 3D printed covers.

STEP 5: Mount the Motor

Attach the motor to the box using some kind of a mount. You can make your own, but I bought it along with the motor. Next, attach the rotating object to the motor (the disc with a bearing in it in my case). Again, I used some 3D printed connectors, but it's only suitable for the scraps I used and so I didn't think it'd be helpful to share the designs - but let me know if I'm wrong here!

STEP 6: Prepare the Electronics (speed Control Unit)

It's time to connect everything.

• Place the speed-controller inside the box and hold it in place (with screws or hot-glue).
• Connect the motor to the controller.
• Connect the potentiometer (the knob) to the controller.
• Connect the power-supply (12V, 2A or more) to the controller.

Make sure everything is working properly before moving on!

STEP 7: Final Attachments

Almost done! Just a few final details :)

• Attach the knob to the other side of the potentiometer.
• Connect the arm to the rotating disc (or what-ever you're using in its place).
• Apply some hot glue to seal the hole of the power-supply (so the cable can't be pulled out). You can use a zip-tie instead if you like.
• Finally, I wanted to make sure the box can't be opened too easily, but that I could open it if needed (make sure everything is working before proceeding!). I took a small piece of scrap metal and drilled a couple of holes in it (kind of like a mending plate). I then attached it to the top and bottom parts of the box, holding the box closed.

STEP 8: Done! ... Almost :) (+ a Peek at the Previous Version)

At this point, I thought it's all done (see the first 2 images). I was pretty proud! But apparently, 3D printed parts can be a bad idea sometimes! . 3D printed objects rely on the adhesion of each layer to the next. So, for a 3D printed part to fail, on one of the layers has to fail. In my case, the connector holding the swinging arm and the rotating disc broke, so we had to fix it (see 3rd image). I'll show you the fix in the next step, but first...

Stroller Rocker Version 1.0 - and why it had to be replaced!

I thought this is a good place to mention that this is actually the 2nd prototype I've been making for this project! The first one was based on a linear actuator controlled by an Arduino and a Bluetooth-connected app (see 4th image). This was really nice to play with, and taught me quite a lot, but it was over-complicated. Making gentle, speed controlled, strokes using a linear actuator is not simple (you need to keep track of it's position and so on). The simplest way to make a gentle motion is by having a sinusoidal motion - transfer circular motion (rotation) to a linear one. Moreover, I wanted to make this product available to as many people as possible, and as popular as Arduino is for tinkerers, most people are still unfamiliar with it. These two reasons made me abandon the old design for the new one :) Let me know what you think!

STEP 9: One Mechanical Failure Later

As a quick fix to the broken 3D printed connector, my father suggested that we weld bolts to metal rod which makes the swinger-arm to act as 'breaks', and another bolt to the rotating disc (see picture, it's much clearer than my explanation). This seems to work well, and since then, the cradle rocker has been operating pretty often.

Future improvements include replacing the motor with a slightly quieter motor, using stronger suction cups, and putting everything in a more elegant box. Other suggestions are more than welcome!

If you like my project, feel free to visit my instructables page and my website! for more! See you soon!

Also, if you want to support my future projects, you can buy me a coffee :) 100% of all donations will go into new projects! Thanks!

Comments

[davidov]

Great work Nir! I was searching a lot on the internet to find a solution for this problem, and your solution seems to be the best! It is easy to build, and powerful enough to swing the stroller. I have one question though. Do you happen to have a video without background music? I'm curious of the noise of the motor. Any suggestion on a quieter alternative? Thank you!

[NirL]

Hi, sorry for the late reply. I'll try to see if I have one, but it's
been a while! It does make a bit of noise because I used a geared motor. A friend suggested replacing the motor with a nema17 stepper because it's supposed to be more quiet, but then you'd need a different controller (and I'm not sure about the torque it can hold). If you find a motor with ~20 kg/cm torque you should be fine (you can use a weaker one, but then you'd have to swing slower too). The best you can use is the type of motors used in electric scooters. Those are super quiet, and we actually built another version of this stroller swinger using it. These are a lot more expensive though, and require a controller of some sort as well.
I hope that helps!

[Skyfinder]

I'm moved :D 8yrs ago I had the same problem, same reasoning and same solution :°D It's amazing same problems leads to common solutions and designs... Great project, in my opinion, this should be a commercial product, still wondering why no one here in Italy made it or sell it.

[NirL]

Haha that's great!! Do you still have a picture of it?? I'd love to see!
Actually, my brother is trying to make a product based on this prototype I made ^^ They're making some big changes but it does seem like a pretty universal problem without a proper solution!
Thanks a lot for your very kind comments! It means a lot :)

[Skyfinder]

At the epoc I had another idea: instead of a circle, think it like a CAM: a spiral path of holes or guide, where changing the union point, changes the amplitude of the shaking :) Every baby, loves a different shaking, smaller or bigger. WIth the trimmer you change the speed ok, but with the CAM, the amplitude.

[NirL]

That's a great idea! :) I was thinking the same, and I even made a model for it (see the GIF below), but for the sake of simplicity I decided to stick with the scraps I had laying around. By the way, since the swing of the stroller is in one direction, its motion is:

x(t) = A * sin(2pi * f * t) , where A is the amplitude of the motion, and f is the frequency of rotation. Since we can only feel acceleration, we feel the second derivative of this equation with respect to time:
d^2(x) / dt^2 = - A * (2pi*f)^2 * sin(2pi * f * t)
So, the baby will feel acceleration with an amplitude of
A* (2pi*f)^2
which is linear in A but quadratic in f (the frequency of rotation). So we can modify the acceleration's amplitude more easily by increasing the frequency of than increasing the swing amplitude! (but this also changes the frequency of the swings of course).

[cburg]

What Great Idea and you did a nice job putting this project together. Would you have more information on the motor you used. The link no longer looks to be working.

Thanks and I will check out your website.

[NirL]

Thanks a lot for the nice comment :) Oddly, the link seems to work for me. Does this one work?
https://s.click.aliexpress.com/e/_9v6zCA
It's supposed to be the same one. If it doesn't, let me know and I'll try to replace it! I've been writing this instructable on&off for a few months now so maybe things have changed. Thanks for noticing! :)

[cburg]

Thank You for the reply. Yes, this link works. It turns out your link was fine, The problem was the fact I installed windows 11. (Big Mistake!!!!) I have had nothing but problems. I suggest anyone reading this to stay away from Win 11 until MS gets the bug out.
I wish you luck in your future projects.

[NirL]

Ahh... My windows keeps asking me to upgrade and I've been tempted to go for it, I guess I'll wait a few more months! Thanks for the tip! And for your kind comments!

[kmpres]

Great idea! Some sound proofing (foam pads) in the motor box and some rubber grommets under the motor's mounting screws should quiet the ride for your little one. I also suggest you enclose the works including the swing arm mechanics in a bigger box in case your toddler son decides to exercise his budding engineering talents by putting his fingers where they shouldn't go.

[NirL]

These are great ideas, really! :) I plan on making a new version of which includes sound proofing and housing everything in a larger box. Thanks a lot for the ideas and for the nice comment! :)

[schaude]

Good idea and well made!

For a further project I used a cheap motor from a windscreen wiper from eBay. This motor with gearing runs perfectly slow, it works with nearly any DC power supply and with voltages from 2 up to 14 V you can change its speed.

[NirL]

Nice! I've been looking at windscreen wiper motors as well, those are probably a good choice for the project. I had issues figuring out the torque they can apply, but I'm pretty sure they'll work well:)
Thanks a lot for the kind comment & for your input!

[Felix Pz]

Windscreen wiper motors are strong. I would expect a high torque. A friend of mine made a jigsaw with one of them to cut metal cillinders. However, I guess they are noisy.
On the other hand, I kept the motor of a lateral car window glass. The mechanism got broken but the motor is fine. It runs from a very few volts (maybe 2.5v, I don't remember it right now) up to 13v or more. It's very silent when runs slowly. I think it has enough torque for a project like mine. Maybe I'll use it.

[NirL]

Thanks for the input Felix :) I'll look around for a windscreen motor too and see how it works. Good luck with your project! Hoping for an update ;)

[Felix Pz]

I'm here taking some ideas for a project similar to this, though mine doesn't need to be babyproof.
As a tip for babyproofing, I suggest to hide the potentiometer somehow inside the box and make it accesible only by opening the box or, better, by a small hole (smaller than a baby's finger), letting the adults to act on it with some screwdriver, pencil, or similar.
I also would lock the box with some locker or shackle to avoid babies opening it.

[NirL]

Thanks the comment and for the tips Felix! :)
I actually did lock the box - I screwed a mending plate to both sides of the box, keeping it closed (I probably didn't write it clear enough, especially since I didn't have pictures of it). May as I ask what project are you working on?? I'm curious :)

[Felix Pz]

My project is still in the world of the ideas...
I want to make a "swing" for recharging Pb-acid batteries. This way, the electrolite inside the battery mixes continuously during the charge, leading to (presumably) a better build up and distribution of Pb on the plates.

[NirL]

Sounds useful, I wonder if it actually leads to a better build up! Sounds like a nice experiment!
You're probably planning to use some kind of a turning wheel like mine to make a smooth circular motion. Actually, you reminded me of an old instructable I saw, which sounds kind of exactly what you're looking for (maybe yours has to be sturdier if the batteries are heavy, but still):
https://www.instructables.com/DIY-PCB-Shaker/
If you ever make your own shaker I'm sure people would love to see it on the site! I know I will :)
Good luck with your creations :)