Archive for the ‘Uncategorized’ Category

Project meeting June 28

Sunday, June 27th, 2010

Come on down Monday night and join in on the BrushBotComm activities.  We’ll be continuing with the IR receiver transmitter protocol development and mounting the boards on to brush bots.

6/28, 7pm bRrainSilo

http://brainsilo.org/wiki/Location

Hope to see you there!

Monty

Project Meeting June 14

Friday, June 11th, 2010

The next group project meeting is Monday evening — same time, same place:
6/14, 7pm bRrainSilo

http://brainsilo.org/wiki/Location

How many people want to build up some BrushBotComm boards using the Tiny84 at the meeting?  (Tiny44’s are still out of stock)
If there’s enough interest, we’ll do it — please reply on the mailing list, or below, with the number of Tiny84 based boards you want to build.

For those with a board already, let’s start working on the Rx/Tx protocol now that we have the IR working, and figure out the best way to strap these boards onto the BrushBots!

See you all Monday!

Monty

No project meeting Monday 5/31

Friday, May 28th, 2010

No project meeting this Monday 5/31 as it’s a holiday.  But don’t let that stop you from dedicating your three day weekend to concocting the best IR communication protocol the Portland area has ever seen!  Or just kick back and enjoy some nice BBQ weather.  Whichever.

It would be cool to hear about any progress with the latest (ver0.3) IR Tx/Rx code that was released a couple weeks ago though.  Anybody try it yet?

Next project meeting: June 14.

Monty

PARTS Indoor Challenge and mouse sensors

Saturday, May 1st, 2010

After this morning’s PARTS meeting and Indoor Challenge, a few of us were talking about using optical mouse sensors for tracking robot position rather than wheel-based encoders.  Optical mouse sensors use optical-flow techniques to determine X & Y motion based on differences between successive snapshots of the underlying surface texture.  These sensors contain very-low resolution (18×18) cameras and all the necessary DSP to distill the information down to a delta-X and a delta-Y value.  It’s possible to read the raw image data out as well.

I’ve been wanting to play around with optical mouse sensors for a while, and the PARTS Indoor Challenge seemed like a good target application, so I threw some Avago ADNS-2620 sensors into the last DorkBot group order.  Unfortunately I didn’t have time this last week to do anything with them.  I figured I would need two sensors to track X, Y, and rotation since the mouse sensor doesn’t do rotation.  This certainly isn’t a new idea — mouse sensors have been used for robotics for quite a while, but I hadn’t done much research on it until now.  Here are some good links:

Precise Dead-Reckoning for Mobile Robots Using Multiple Optical Mouse Sensors (PDF)
Evaluates accuracy of two vs four mouse sensors compared to encoder-based dead reckoning.
Two sensors are significantly better than encoder-based DR if the robot speed is less than the max rate of the mouse sensors; four sensors are even bettter.
Four sensors are still significantly better than encoder-based DR even when the robot speed is greater than the max rate of the mouse sensors.
Testing was done on a felt surface, however, so the variability of the floor we’ve been running the PARTS Indoor Challenge on may require more than two sensors for robust positioning, even at slower speeds.

Cody’s Robot Optical Motion Sensor #1 (CROMS-1)
Nice writeup on hacking an optical mouse sensor, including creating a custom lens assembly for increased range.

Implementation Of An On-Chip Insect-Inspired Optic Flow Based  Navigation Sensor
NASA Tech Brief referenced by Cody’s above writeup.  Using optical mouse sensors with custom lens assemblies for flying robots (at low altitudes).  Overviews the optical design methodology and presents data from actual flight testing.  Concludes that optical mouse sensors are usable for terrain-following behavior on a robotic-flier.  Free registration is required to access the report.

Required components for optical mouse sensor (if you want to start from scratch rather than hack a mouse):
(These aren’t necessarily the best mouse sensor for robot navigation, but they are readily available.)

Avago ADNS-2620 optical mouse sensor
Data Sheet
Purchase:  Mouser 630-ADNS-2620 ($1.58, qty 1)

Avago HDNS-2100-001 lens
Data Sheet
Purchase: Mouser 630-HDNS-2100-001 ($0.18, qty 1)

Avago HDNS-2200 LED alignment clip
Data Sheet
Purchase: Mouser 630-HDNS-2200 (Non-stocked/Not available in small quantities! Grrr.  I think I can do without it.)

Avago HLMP-ED80-K0T0 LED
Data Sheet
Purchase: Mouser 630-HLMP-ED80-K0T00 ($0.39, qty 10)

More to come!

Monty

Hello

Saturday, April 3rd, 2010

New to the Portland area, therefore, new to the Parts group.

I’m currently working on a rather large robot that will use several microprocessors. I have just added AVR processors to the list of processors that I work with. Now to get them to all talk together. More later as I am sitting in the April meeting now…..

Flickr Pool Created / SMT Assembly Photos Posted

Saturday, March 27th, 2010

Hi folks, I created a Flickr pool for us.  You have to be approved to join in order to post new photos to the pool.

Here’s the link:
http://www.flickr.com/groups/portlandrobotics/

-Pete

cool site

Thursday, March 25th, 2010

these penguins have swam technology included into them. This pdf does not go into detail like I would like but very interesting!

http://www.festo.com/cms/en-us_us/10290.htm

click on brochure link on the right.

I think I am going to be researching this company for the next couple of days. very Intersting!

BrushBotComm board build follow-up Monday

Sunday, March 21st, 2010

The bRainSilo remodel progress is looking good for a group project meeting on Monday, so we’ll follow-up on the BrushBotComm board build we started a couple Saturdays ago.  We’ll continue assembling boards for those that didn’t get theirs built last time, and hopefully we can start programming them.

Time: Monday 3/22, 7:00pm
Location: bRainSilo: http://brainsilo.org/wiki/Location
Bring:

  • BrushBotComm boards if you already have them, built or not
  • Money if you haven’t paid for boards/parts yet
  • Soldering iron — if you have a decent one with a fine tip.  We still need to solder up some programming cables.
  • Desk lamp if you can — we didn’t really have enough light last time
  • Vision enhancement devices — I’ll bring my stereo-microscope and what magnifiers I have, but I think we could have used more last time

See you Monday!
Monty

Meeting Place. What would happen….

Sunday, March 7th, 2010

What would happen if we had swarm board development at BackSpace on a day other than Dorkbot Monday. Granted, lead and food don’t go together. There is not a lot of exposure to lead.  The meeting at the University was low key enough that I don’t think anyone would mind too much if we did the same thing on a slightly smaller scale. Limit people placing parts on boards to 4 and “baking” to 4 at the same time.  And, the process is close to smoke free. That might allow more people access to the venue without much hassle.

Next Meeting – March 6, 2010

Thursday, March 4th, 2010

Beginner CTL: TBD

Advanced CTL: Surface Mount Circuit Board Soldering (Scott Dixon, Jim Larson

Announcement: the rules for the new PARTS Indoor Challenge are posted. Get your robots ready for the April 3rd Meeting!

After the main meeting, the group build of the BrushBot controller will take place.  Those not participating in that may want to go watch the rest of the Autodesk Oregon Regional FIRST competition at the Memorial Coliseum.