Dancing 3 inch tall brushbot

While I'm waiting on parts (extruder, beated bed,  and hotend) for my RepScrap 3D printer, I thought I would have a bit more fun...


Someone sent me this hilarious video, and it started me thinking...

 

 

I frequently attend various  vendor trade shows,  and invariably, the vendors hand out useless trinkets as advertising...  I usually do one of three things with these... 


    1) anything electronic gets tossed into the parts bin, 

    2) anything of a "toy" nature goes to my children (yes, I got that order straight) 

    3) everything else gets tossed them into the garbage.

 

 

 So I happen to have a pair of these "electronic devices" in my parts bin.  I think they are commercially known as "Hexbot Nanos


They would effectively replace the toothbrush head and pager motor in the above video....


But I also received one of these little wind up distractions to the left here...  


Mechanical spring wound clockworks makes him do a little dance...  


For some strange reason, he hadn't quite made it to the kids yet...  hmmm....






It looks like those Hexbots might just fit the bottom of his feet..... 


Maybe I could run them directly from an ATtiny84 as in THIS blog... 

yes, I know I should add a transistor to drive each motor, but when I looked up the current draw on a free running pager motor, low and behold they are around 20-40ma... well within the range of the ATtiny84 pins capability.


 Current and RPM specs:

 

Voltage

RPM Current (free) Current (stall)
1.5V 9700 17.5mA 120mA
3.0V 18420 22mA 260mA
5.0V 31900 32.1mA 420mA


 

 

 

 

 

 

Add a Sharp IR proximity sensor onto his chest, a small LiPo battery on his back for balance, the gratuitous leds on the head, and I think we just may have ourselves the next project.... It doesn't get much simpler...


(ok, ok... yes, I'll likely wire in a connector for the AVR programmer... but that's it...  well... and maybe find another pager motor to replace the spring would mechanism that makes him dance... but THATs it... really...


maybe...)


 

I thought I would put this picture in, just to show the scale... 

 

 

 

 

 

 

Update: 05/21/2014
Well, I've had some time to think and plan, and dismember the cheerful little dude...



 

Here is the sum of his parts.

You'll  notice the little white box lower middle of the picture.  That is the spring wound mechanism that made him dance...


It fit inside the body, in an area roughly 2.5cm high by 1.5cm wide by 1cm deep.

The is the space I have for electronics...




 This is the underside of our friendly Hexbot Nano, with the battery removed. I'll be simply connecting to the positive and negative battery wires for this build.

 
 

Opened up, you can see the miniature "pager" motor with the offset weight that vibrates the Hexbot Nano.  
I've also placed the protection diode inside the body of the Hexbots, as there was no room on the main circuit board. 

 
 

  I then hotglued the Dancing bot's feet onto the tops of the Hexbot Nano's and drilled a hole to pass the motor wires through.

 
Here is the blank board in it's body casing. That's it.  That's all the room I have for electronics.





Luckily, an Attiny84 in socket, as well as a power connector and the ISP header all fit exactly on the board! I couldn't have asked for a better fit! 

 The Sharp GP2Y0A21YK Infrared Distance Sensor is hotglued onto the stub that held the original Dancing bot's head, and the LiPo battery is velcroed onto the front of the body.

 Here, the ATtiny84 control board is placed into the body for sizing. 

Assembled, and ready to code.   I've placed the AA battery in the picture to demonstrate the size of this guy.






 Watch this space over the next few days, as I get this guy up and dancing... 

 (currently having problems with balance/center of gravity... this too will be conquered)

 

 

References and prior art:

 

https://www.youtube.com/watch?v=4_4POEtLd_4

http://www.hizook.com/blog/2011/09/08/infrared-remote-controlled-rc-steerable-vibrobot-created-naghi-sotoudeh

https://solarbotics.com/product/rpm2/

http://forum.arduino.cc/index.php/topic,6528.0.html

http://www.rcgroups.com/forums/showthread.php?t=322209

http://www.makershed.com/BrushBots_p/msbb.htm

http://lycomingrobotics.wikispaces.com/BrushBots

 

 

 


walks around on brushbot feet, and hopefully avoids obstacles...


This is a companion discussion topic for the original entry at https://community.robotshop.com/robots/show/dancing-3-inch-tall-brushbot

I really want to see this

I really want to see this guy in action!

Check out the second video…

It shows the little guy dancing on his windup spring… 

 

I want to run that off a pager motor too…

 

Something you may want to consider.

Motors have a bad habit of generating back EMF when they are stopped, as I recall. The problem one can run in to is that this back EMF can generate a voltage that is several times if not an order of magnitude above the original drive voltage. Put another way 20mA may not harm a uC pin, but, 6, 12, or even maybe 36 volts will definitely not make said micro happy.

Mind you, I am speaking/typing from things I have read over time. The info may be outdated or COMPLETELY WRONG. :slight_smile:

PS I hate that the last two comments I have made on your posts have not been positive. I haven’t DONE anything of note for a year or more. Your work is impressive and to be praised. I just want to make sure you have a heads up on possible pitfalls(?).

youre absolutely right…

Of course I’d be a fool if I didn’t put the inverse diodes across the motors…

And I appreciate the comments, even when not fully positive. I would consider this helpful critique. Not harmful criticism.

 

Much better than me blowing a chip and writing a rant on that, and then you’d be thinking Jeez, I could have told him that!

Cheers Bird.

 

 

 

that’s so cool unix. the

that’s so cool unix. the size, the balance, the dance. just great.

-Ashim

 

I think balance is going to be my worst enemy…

This thing has virtually no mass, but a high center of gravity.

Keeping it upright with those buzzing feet, and a sharp IR hotglued to his belly will be a challenge.

 

**I’ve updated the schematic… **

brushbot_bb2.jpg

I figured that I would add the transistor drivers while installing the protection diodes... I may not have room though. 

The entire enclosure for electronics is  3cm x 1.5cm x 0.8cm

I've also added the ISP header and a very small speaker for potential noise making...  What's dancing without singing?

 

That is very creative,

That is very creative, thanks for sharing it. As everybody here, i want to see him dancing and hear him singing…please proceed and don’t get disturbed by our comments :slight_smile: