So, I'm fairly new to Aruino (i've done a couple projects and have played around with coding) and I love what I've done and learned about Arduino so far. That's why I'm trying to figure out the following:
I'm a brand new dad to a 3 week old beautiful baby boy and I'm wanting to use some hardware connected to the arduino to make a bassinet type baby bed rock back and forth. I have a vision in my head of what could possibly work hardware wise, but I just don't know what it would be called or where to start looking.
I have also a vision in my head : the rocking going into a resonance frequency and tossing the baby through the room.
A thread and a servo motor is probably enough. But the servo makes an unpleasant noise.
To be serious: congratulations, love and happiness for all of you.
Hahahaha! I have some great visuals in my head now of babies flying across the room. Thanks for that
But in all seriousness, the 'thing' I'm thinking about mounting the hardware on is something like this: http://goo.gl/Mp8ILI
So putting something like you had mentioned on the bottom of the legs that makes it move, maybe a 1/4" at most. In this case, would you still recommend a thread and a servo motor?
Suggest you sort out the physical side first - find out what sort of frequency you want, how much force and displacement you want in order to maintain the desired amplitude of movement. Driving through a tension cord with some flex in it would seem like the safest approach. For example, you could use a small geared motor with a crank on the output shaft. You need to sort out the mechanical characteristics to spec the motor, gearbox and crank though.
This project is simple enough that it doesn't require an Arduino. We have a commercial rocker chair for our baby and it uses a small DC motor that runs on 4x D-cell batteries. The crank is connected to the rocker via a small spring, the control knob runs the motor at different speeds. Eventually the rocker hits its resonant frequency.
If I may offer a bit of advice. We have two kids now and found that the rocker is a bit of a waste. Both boys only used it for a very short period of time. (several weeks) before they didn't need or want to be in it anymore. My advice would be to not do this project, it will be very short lived.
The frequency should be the natural frequency of the baby pendulum. Forcing any other frequency would be not only energy inefficient but, I would assume, also not comfortable.
+1 on the spring / tension cord coupling. Rigid connection would most likely result in damage to the motor and/or coupling. You would want to provide some breathing room for the moments when you put the baby in and out or when you want to take over and switch to "manual control".
@Digger - thank you for your advice and for explaining what you have/had. Do you know what brand your commercial rocking chair is/was? Have a link by chance?
Thanks everyone for all of your suggestions. Very helpful!
I finally managed to find an auto-rocker setup using a servo, a spring and a piece of bungee cord.
The key was finding something flexible enough to allow the right back and forth motion.
At this point I see no need to add a sound trigger, as my goal is simply to give myself a little more freedom from having to manually rock him to sleep, as opposed to something like a robotic nanny.
As much as the current setup seems to work, I'm guessing somebody with more of a background in physics could probably achieve better control of the rocking motion with something like a solenoid?
Update-
While the initial design did do the job once set up properly, it had its drawbacks. Namely, it required way too many pieces to hold the servo in the right position, and even then it required constant adjustment to get the proper motion.
A much better approach was suggested to me by a friend who had a baby the same week as I did... Instead of attaching the rocker to a chord controlled by an exterior-mounted servo, he suggested mounting a continuous rotation servo on the rocker itself with either a cam shape, or single arm propelling the rocker forward on each rotation.
I can post photos later, but the result is a much simpler setup with a far more consistent motion. There is one significant drawback however... With the first setup, the sound of the back and forth motion created just the right amount of white noise to put my son to sleep. The continuous rotation servo OTOH emanates a high pitched whine of the type that signals distress or strain in both the animal and mechanical world alike! As for my purposes, the continuous rotation servo is really just a geared dc motor in a hobby form factor, I wonder if I could replace it with a different motor that would produce less noise? Or at least, one that doesn't sound so grating?
