Christmas break show and tell thread.
Martin_H
Posts: 4,051
So Heater asked about people's plans, but this is my attempt at a show and tell thread. Did you do anything cool over the holiday?
My project started when I asked myself how hard could it be to write a gcode interpreter? I figured that I could write it in C++ in an afternoon and could move onto another project. It turned out to be a much thornier problem* than I expected, and consumed several days of effort. But here's a video of the results:
I'll post the source code and gcode over in my tiny robot arm thread. As an FYI, this was supposed to be the scara robot arm, but it couldn't push down hard enough to get suction, so I switched to the revolute arm.
* The hardest part was getting the software flow control correct as I wanted to use an existing PC tool called grbl control. It uses a standardized flow control scheme that I needed to reverse engineer. The second hardest part was learning gcode since it's not human friendly. The whole project left me with respect for Forth because it solves the serial I/O for you.
My project started when I asked myself how hard could it be to write a gcode interpreter? I figured that I could write it in C++ in an afternoon and could move onto another project. It turned out to be a much thornier problem* than I expected, and consumed several days of effort. But here's a video of the results:
I'll post the source code and gcode over in my tiny robot arm thread. As an FYI, this was supposed to be the scara robot arm, but it couldn't push down hard enough to get suction, so I switched to the revolute arm.
* The hardest part was getting the software flow control correct as I wanted to use an existing PC tool called grbl control. It uses a standardized flow control scheme that I needed to reverse engineer. The second hardest part was learning gcode since it's not human friendly. The whole project left me with respect for Forth because it solves the serial I/O for you.
Comments
I'm finishing up my Spider robot build tonight, should have some video tomorrow. I had fun yesterday building the controller board and the twins approve: http://www.youtube.com/watch?v=ICAyUKGNldY
David, that is quite a nice looking ornament.
The LED ring is mounted behind the plastic ornament.
As I mentioned in thread about the cheap LED arrays, I experimented with some MAX7219 chips for the first time.
I was really please how quickly I was able to get text scrolling across the arrays.
(This is the same video I've posted twice before to the forum.)
I've also been working on my hexapod. I'm also starting to play with the remote Paul K gave me.
I've added XBees to the hexapod and the remote now it just a simple matter of programming in order to get the one to control the other.
Try looking around for a suction device used in packaging lines where an individual folded box has to be picked up one by one to put some item into. It is like a suction cup with a hole drilled in it and a hose going to a vacuum source.
BTW, I love your robot!
Best,
Joe
Thanks for the suggestion and the compliment.
for some BLDC hall-sensor motors that are currently available on eBay. The RP23M-52V24 motor
comes with hall sensors and dual shaft but no encoder, and a while ago I experimented with the
AS5035 magnetic rotary encoder chip.
So there's going to be a 3-phase bridge and control board that mounts where the encoder normally
goes, with a hole in the middle and a little mezzanine board that plugs in over the end of the shaft for
the AS5035 to sit. The motor has a non-magnetic stainless shaft go super-gluing a magnet on the
end is all that's needed to give a nice symmetric field for the AS5035 to work with (it gives 256
pulses/revolution).
Motor (rated 200W, 24V, 3600rpm no-load, inter-winding resistance 0.4 ohms):
The board layout in development:
And the clever little AS5035 chip http://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&ved=0CDIQFjAA&url=http%3A%2F%2Fwww.ams.com%2Feng%2Fcontent%2Fdownload%2F1284%2F7211%2FAS5035_Datasheet_v1_0.pdf&ei=J1jDUt6_O6fR7AbnyIHwBA&usg=AFQjCNFY70p03YVn12dC7CwA9wCoHT6txA&sig2=DZvQ8b_UUR1KYc2HizTw6g&bvm=bv.58187178,d.ZGU
The diametrically magnetised 1/4 inch magnets are available from supermagnete.de I believe, IIRC.
The motors seem to be surplus stock or somesuch because they are going for £25 from a UK recycled goods supplier.
In the course of working on the board I realized some neat circuits for visualizing the hall-sensor outputs on a group
of 6 LEDs:
BTW: HNY!
Full story:
http://localroger.com/nixie/nixie.html
It would have been much easier to use a Microchip 3.3 volt ADC and have 12 bit resolution, but I used what I had on hand and the Propeller Mini does provide 5VDC. I used 3 2n7000 for bi-directional level shifting to control the ADC chip as that seemed the best way to deal with having a shared Data In and Data Out line.
Youall may think my choice of connectors for the Mini are a bit odd, but I wanted the Mini to be able to lie flat and the male pins are all protected on one side in this arrange -- better protection from damage to the i/o. I can easily connect cables or as seen in this case, a daughter board.
@localroger, with those nixie tubes you're all set to build a 1960's era computer that conquers mankind.
@erco, great spider bot. You've also thrown down the gauntlet for the double orbit challenge.
Actually, a funny fact about my avatar -- the movie Colossus: The Forbin Project was made without the use of a stand-in computer for Colossus. All of the Colossus "text displays" were obviously slides being scanned by a video camera. And while they had "modern" video chat it was impllemented with realistic early 1970's tech, with CRT monitors and huge vidicon-based cameras in massive desk-mounted consoles. I'd have to watch it again to be sure (always a treat) but I'm pretty sure there wasn't a Nixie tube to be seen, as they were trying to be "futuristic" LOL.