Perpetual Ball Roller


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Overview

This machine is controlled by a PicAxe Microcontroller. A servo (used for steering in R/C cars) is used to tilt the track for a ball to roll round. The degree of the tilt can be controlled by a potentiometer in manual mode or in automatic mode preset instructions on the microcontroller tell the servo how to move.

I struggled to find a name for this. I eventually settled on Perpetual Ball Roller. I like the "perpetual" part because it gives an idea that the ball will just keep going round and round but the name doesn't really describe what it is. I can't believe someone else hasn't made something similar but because I had no idea what to search for on Google I haven't found anything. If you are wondering what it is the best thing to do is it to watch the video. I'll detail some of the features here incase I didn't mention them on the video or you can't watch it.

Answers to feed back

Thanks to Hack-A-Day for posting this!


Electromagnets instead of servos
Electromagnets would probably work. I think it would be trickier to get so many different positions accurately. The simplicity to MAKE the project would decrease even if the viewing of it was not. If anyone tries it then send me a link to the video and I'll put it on this page. It is not something I am personally going to try.


The need for sensers
I originally thought they would be neeeded but the ball justs finds it's way into the rotation. The speed could be changed through the potentiometer and that was the original idea. I would not be particularly exciting though and I prefer the erratic routines.


Need the Microcontroller?
You could use a premade potentiometer to servo board. This would give you manual control. Problems with this are that it wouldn't be much cheaper if any cheaper at all and the main problem is that limits need to be set for the rotation of the servo or the device will rip itself apart.


Muscle Wire and rotating tracks etc
Not something I would do personally but would love to see it done.


It's not perpetual!
The track is a circle, that is no start and no end. It would go on for an indefinite period of time as you could change the servo batteries very quickly while the ball was still rolling. For added cost you could even make it solar power. As I explained before perpetual seems like a nice way to describe it. I left "motion" out so that people wouldn't think I was claiming perpetual motion. If it really gets under your skin... you may want to disconnect your computer from the internet.

[Lisa] In this house, we obey the laws of thermodynamics!


Videos

Perpetual Ball Roller Quiet Operation - Manual
Perpetual Ball Roller Quiet Operation - Automatic
Perpetual Ball Roller - Latest Routine

The video is slightly out of date. The code on now will give slightly different routines if you study it carefully.

Construction

Coding

The code is written in Basic and in theory should be easy to understand. I am a pretty messy coder so it may be difficult to understand. Read the comments and if that still doesn't help email me (address at bottom)

Text File of the Code
BAS File (open in Picaxe Programming Editor)Putting it all together

Here I will go into more detail on how it works so if you are wanting to make your own this is what you need to read

Parts List

  • Picaxe 08m
  • Resistors, switch, potentiometer
  • Stripboard
  • Suitable strong servo
  • 4 x AA battery pack
  • 3 x AA battery pack
  • Wire for frame

I have not included tools like soldering iron and solder etc. You will need a soldering iron with a decent rating (mine is 50W) to be able to solder the wire frame together.

The circuit is nothing fancy. It does not need to be as compact as my one but because of it's simplicity I just made it as small as possible. If you don't know how to put together the circuit or have questions on it then email me but I suggest you try some very simple PicAxe circuits first if you've never used one before.

For the switch, left is manual, centre is off and right is automatic. On manual mode the potentiometer is used to change the resistance that can be detected by a pin on the microcontroller using the readadc comand. This is then converted to pulses sent to servo which change its postion. On automatic mode the potentiometer is used to select 1 of 5 routines for the tilting of the track. The final routine is actually random mode which effectively cycles through the other modes.

The bearings that support the track are nuts and bolts. I've found these to be useful in various applications where motion won't go round and round (they would tighten!) but instead go back and forth. The metal loop that connects the servo to the track has extra length so a high level of tilt can be applied.

It is a completely useless desktop toy but so far people that have seen it have liked it. There is something in its simplicity that makes it easy to understand once you have seen it but it is unlikely to be anything you've thought of or seen before.

Links

Unigamer's Rolling Ball Sculptures - These are my Rolling Ball Sculptures
Picaxe - The official website
Tic-Tac-Tunes - A cool little musical toy that use Picaxe

Contact

unigamer [att_no_spam] gmail . com
change [att_no_spam] to @ and remove spaces