Inspiration/ideas needed - making a toy 'jump'

Using Arduino Project Guidance
#1

So I recently got a cat. Who's pretty fantastic. And my brain says, hey, use your love of tinkering with electronics and make her some toys! I run downstairs and grab my box of goodies and brainstorm.

Well what I made is pretty sweet - but it's missing something.

She loves playing with those little stuffed mice - bats them around, throws them, chases them after she swats it down the hall. I thought - what if it moved on its own??

Using an Arduino Pro Mini I had, an accelerometer, and a vibration motor/disc, I made a toy that knows when it's being played with. After it sits still for a few seconds, it vibrates. I just tried out the prototype on her just now and somehow, my guesses at the timing of it were perfect. It seemed like it always went off and brought her attention back either just as she was losing interest, or just when she knew she won, and had it pinned under her paw. The look of WTF on her face when it buzzed under her foot was priceless.

The problem: The little vibration motor doesnt make it do much more than buzz if its on a carpet. It dances across the floor a little in the kitchen, but in the living room, it just sort of goes BZZ BZZ.

Any creative minds out there have an idea for how I can make it move more? I dont want anything she can get caught/hurt on, and the final version of this I see covered in fleece so her claws can grab onto it and toss it about. Right now, a 3d printed plastic shell isnt the best for gripping. I also want to keep it as small as possible. Right now it's about 45mm long and about 25mm in diameter. I'm going to lose some weight and size soon - the Pro Minis I have on hand are 5v versions - ordered some 3v versions today which will let me lose 2 batteries (4 LR44's right now, down to 2 when I switch to 3v) as well as lay the batteries flat instead of on their side, reducing the diameter.

I thought about maybe making it into more of an egg shape and using a mini DC motor and attaching a weight on a long (well, long for the size of the thing) arm and trying to spin the motor slowly so the weight makes it roll about. Problem is in something this small, theres not a lot of room for the arm. Also the size of the pro mini limits me - I cant exactly cut it in half to make room for a spinning weighted arm in the center of the egg shape.

Besides that, any other ideas anyone may have? I thought of a small spring loaded arm with a weight on the end that can be drawn back and released, but anything I can think of to draw it back and release it is too complicated to fit in a tiny enclosure.

Any ideas?

#2

You used to be able buy a toy clockwork mouse that had a rotating rubber tail and the tail sort-of acted as a wheel to make it move.

...R

#3

Hmm thats an interesting idea I hadn't considered. If I have a 'tail' thats outside the body of the toy, I can make it spin, and the tail hitting the floor would make it move enough. As long as the spin isn't very fast it wouldnt be able to hurt the cat (whipping it in the face, etc). If I used some stiff steel wire (covered in fleece or something soft) it'd be strong enough to move the toy.

Very cool idea. Thanks. Might need a geared motor to use that - any standard DC motor would spin too fast I think. My local microcenter had a few of them. I'd use a servo but even the smallest one I have seen is pretty big to fit inside, plus the power requirement for a servo is pretty beefy.

Open to any other ideas anyone has too. Less external moving parts = less chance of breaking when being swatted about :slight_smile:

#4

You can make a self-contained object jump by rapidly shifting a weight inside it. Example: Small cubes that self-assemble - YouTube

#5

I've been considering that but I'm facing a size issue - keeping it small. I might need to upscale the size a bit if I go that route. Though, I did just have an idea. Given my case is 3d printed and it needs to withstand cat whacking, the radius of the toy is a bit wider than the pro mini. As it stands now, the arduino is actually off center to make room for the batteries. When I get the 3v arduino, I'll need less batteries...

I'm thinking that maybe I can make the toy a cylinder shape. With a geared rod down the center. Inside, I pack as much of the weight onto one side of it as possible, mount a motor with a gear to the board/etc, and instead of a vibration, I turn on the motor which would force the entire set of innards to rotate around the center axle. If the case is light enough that would for sure give it a jolt - and if I spun it fast, then stopped, it might even hop or jump.

Very cool idea. Thanks for posting that video too. I'm going to see if I can find anything more about the details about how they built those.

#6

if I spun it fast, then stopped, it might even hop or jump.

Yes, in fact they use a friction brake on a rapidly spinning wheel to cause the jump.

#7

infernusdoleo:
I'd use a servo but even the smallest one I have seen is pretty big to fit inside, plus the power requirement for a servo is pretty beefy.

I have some (from Hobby King) that only measure about 14x16x6mm.

A servo seems ideal for moving a tail back and forth.

...R

#8