Hi all, This is it!
As I got a fully (more or less) functional CNC (see here: http://letsmakerobots.com/node/24217), I can finally start doing what I have intended from the beginning: BUILDING BOTS.
This one will scratch my "must build track robot" itch and at the same time I hope I'll be able to use it as a development platform in general, to test various stuff on it.
Z-39 aims to be completely build using machined parts.
The motors are salvaged from some old CD writer hardware (TIP: there is always good stuff in old hardware ;) ).
The design is all done in Blender from scratch using this thank as inspiration for the track suspensions:
See the resemblence? ;)
The reduction gearbox provides a total of 64/1 reduction in three stages, one gearbox is used for each of the two motors.
The robot is roughly 20 cm long by 16 cm wide, guessing the weight to be about 500 grams.
As the power source I'm emploing 6 AA NiCD accumulators.
For the electronics part, I'm currently using a board I have built before for my previuos attempt at a bot (Sunday), it is a pretty smtraight forward AVR development board including a L293D driver on board (actually two stacked right now :D ). I think it is fairly similar to Ro-Bot-X's uBotino except for the servo connections. It accepts ATMega8/168/368 chips, includes a serial header, an ISP header, and some heae ashort live due to ders for the remaining outputs with GND and VCC connections for sensors and stuff.
Currently the only sensor is a TSOP1738 IR decoder so I'm able to contorl the bot with an IR remote.
The board has currently an ATMega8 MCU mounted, it should be sufficient for my needs for now.
The code (attached below) is actually written in the Arduino IDE and compiled for the ATMega8. Since the Arduino bootloader eats too much space (2000k out of the 8000k available) I'm not using it to upload the code, I'm using ISP for that with my UsbASP based programmer and avrdude.
I chose to use Arduino to write the code out of commodity/lack of time, doing it in C would have taking a lot of time/research.
I used the IRremote library here hacked to drop in size and work with the ATMega8 since it was written for 168/368, attched is the modified version in case you want it.
Current draw is 200-300 mA per motor the decision to use 6 Accus was a good one.
I have currently completed the mechanics of the robot as initially designed, however some improvements are asked for:
- encoders on both output shafts
- maybe I'll add some turret - arm - type of thing on the top
The mechanics performs pretty much as I had hoped so far how ever this guy might have a short live due to material fatigue, it already developed some play where there should be none, oh well I might have to declare this one completed and move on :/
As requested by Pat and Rogue and Jax I shall clean up the DXF files I used in generating the toolpaths for milling and upload them here to spread this guy around the world .. Yeah!
Update! Part files added - z39.zip upthere
And a few notes regarding the above:
- It all has been designed for 3 mm thick material - if you intend using a different thickness you need to adjust lots of it
- There are different sizes of screws and shafts used: 4mm for the big wheels ans the output gear, 3 mm for the smaller wheels, the other gears and suspension parts, 2 mm for the small input gears and the track links
- The motors I used are Mabuchi FF-130SH type here is a description http://home.fuse.net/SCJ/Track/ff-130sh.html if you have others you will need to adapt the mounting holes on the inner casing sides
- Hmm don't remember anything else ... but carefull there might be hidden devils in there ;)
So that's it have fun cutting it, building it an maybe some one sends me a nice lasercut set :D
Update 9-May-2011: Sometimes things that work should be left alone
Guibot contacted me asking if I would like to use the Motoruino on the bot, and do a review on it. Ofcourse I said yes and started tweaking the thing in preparation.
I was experimenting with cutting PCB board for future use so I decided to redo the gearbox using it. The material is far more resilient than wood but it did cut nicely. Sorry I forgot to take pictures :)
So I got it back togheter with the new gears, and new axes too, it was working better, especially after I have added more batteries to a total of 12 V.
Then guibot's kit arrived and I had it soldered, mounted and fuctional. Took the bot for a ride, showed it to my family ... but then yeah disaster stroke, the superglue holding the output gears to the shaft shattered leving the gear spin freeley.
The big problem is that I superglued the whole thing togheter :/ To take it apart it means to break some parts, and fixing it will only be temporary.
So I'll have to do new parts, but this time I will add bearings to support the axes this time, bearings I still have to buy currently.
I'm putting this one on hold for now, will update when I fix it.
Update - 05-03-2012 - EOL
This guy has long been dismantled ... yeah.