I just came back from a walk with my 4-month-old. He's sleeping in his pushchair. I am sitting next to the push-chair and slightly pulling the pushchair's side so it gently rocks from side to side in it's resonant frequency. This motion is what keeps my son asleep. I estimate that I am keeping about 2.5 Hz oscillation with amplitude around 10 mm, my finger is pulling with force around 2 N each cycle. The oscillation is damped a lot.
So I am sitting there, keeping the oscillation going, thinking... How to automate this? What device could be pulling the pushchair so I can make myself a cup of tea?
As a fun challenge, will you help me find/design a device to do this?
- Electro-mechanical, may have a micro-controller
- Has to be easy to tune the frequency. Or even better find it itself.
- As a bonus it could adjust to a range of amplitudes
- It has to be safe = not produce massive G-forces
- Preferably it should be pulling a string or rope that I will fix to a wall.
- A prototype has to be pulled off by me:
- off-the shelf parts, Lego Technic, re-purposing something ...
- some experience with similar crazy one-of-a-kind builds :)
- basic soldering and electrical-engineering skills
- software engineer, programming a microcontroller is not a problem
- some woodworking skills
- can order a 3d print
- under 50 USD in material
So far I am imagining a servo pulling a rope that will be controlled by a microcontroller. I am thinking if it would be possible to attach an accelerometer to the push-chair to find the resonant frequency.