You may remember the previous Electronic Design articles about the 914 PC Bot.
If you missed them, then check out the
914 overall review and
914 .NET review, both by William Wong.
William has now written a new article for Electronic Design about upgrading
the
914 PC Bot with the iGoLogic i3899 motherboard. Of course the 914 uses
standard PC parts, so the task of replacing the mini-itx board is fairly
straightforward. This will always allow the 914 to be 'future proof' as new
operating systems and software appear that are more demanding on system
resources.
If anyone is interested in purchasing a 914 PC Bot, there's one currently on
eBay with quite a low starting price and no reserve.
Bidding has already taken off even though
the auction still has over five days left to run. You never know - you might get a bargain!. Check out
the auction here.
C6Jones720 has written a short report on his work to easily achieve
stereo vision for the 914.
Typically stereo vision is quite tricky because two web cams have
to be used together at the same time. Chris has utilized a CCTV 'quad processor'
to combine up to four video feeds - one into each quarter/corner of the video
stream, so that the resulting video image can be processed in one go and all the
cameras are frame-locked together.
Chris has also started to dabble with Microsoft Robotics Studio 1.5 which
includes some sample vision applications for face and hand gesture detection
that work with normal web cams. It's worth downloading Microsoft Robotics Studio
and running these demos - I found they worked straight away with my web cam
after installing and typing the command lines Chris has detailed into the
Microsoft Robotics Studio command shell.
White Box Robotics are currently redeveloping their Microsoft Robotics Studio
services for the 914 PC Bot. You may remember that there was a Beta release of
the
914 MS Robotics Studio services which is still available on request to those interested. However,
the final release will be quite a rework from this, which allows at this stage,
for input from the community for feature and functionality suggestions.
Microsoft Robotics Studio version 1.5 has also been released since the Beta 914 MSRS services were written, which has come along with a lot of updated
documentation and tutorials. You may or not know that MS Robotics Studio applications can be
written in Visual Studio .NET using MS Robotics Studio as an add-in component to the project,
this allows you to build on top of the MS Robotics Studio framework and existing hardware
support it provides. Those of you who have used the White Box Robotics 914 .NET
components may not find MS Robotics Studio too much of a step in a different
direction, as well as finding that lots of other off the shelf hardware is
already supported.
If you have any feature or functionality requests that you would like to see in
the final V1.0 release of the 914 MS Robotics Studio services, or any other
input that will be useful to the White Box Robotics MS Robotics Studio
development team, then please post in the thread below.
Chris has now taken this theme further to produce an autonomous charging
solution using IR beacons and Odometry. You can read the article in PDF format
here:
914ChargerLocationByBeaconingAndOdometry.pdf (107Kb).
Chris has also produced a film of this is action and put it on YouTube which
can be found below:
This week Odometry
Man has a relaxing time, but not for long - because there's always an odometry
emergency somewhere in the world!!
This is the first episode of a multi part storyline. Please click on the
preview to the left to view this week's episode of Odometry Man in full. (320Kb).
Comic episodes will still be published each week on Mondays and remain archived in the
914 Comic Series section.
White Box Robotics
have updated their corporate website with some new info on the 9 series PC Bot.
There are two new downloadable PDF brochures about using the PC Bot with the
WBR
914 .NET controls and also
Player/Stage/Gazebo, which you can find on the
product overview page. These are definitely worth a read if you've not
looked at using either Linux and Player or .NET on your Bot yet, or you are thinking about purchasing a 914.
The
specification page has also been updated with the addition of a new
off-the-shelf variation of the 914 called the 'Extreme Edition'. The new model
features a 2Ghz Core 2 Duo by default, but a lower spec Bot is still available
as well as any other
custom variation you would like as always.
I got around to making a video of my 914 rotating and lifting head mod which you
can see below.
You'll notice that the lifting motion is quite slow - if you
look closely you can still see the motor shaft coupling rotating right up until
the blue under-head lights start flashing. The lifting speed could be improved
with a geared DC motor and some end switches, but the main limiting factor here
was stepper motor torque vs step speed.
All in all it serves the purpose for housing extra sensors such as sonar and
my IP web cam - the head wouldn't have to lift very far in order for those to
look out. The total lifting height is around 5"/12cm.
This is the last part of the 914 rotating and lifting head mod. You can check
out
part one and
part two if you missed them. All the photos can be found in the
image
gallery.
This week I have been mostly working on the rotating mechanism which I've
rebuilt twice. The main issue is that there is quite a lot of weight to move
around due to the lifting mechanism and it's stepper motor. The original plan
was to use a direct drive method from the stepper motor which was mounted under
the top plate of the chassis in the top drive bay. This worked ok, but even
using half-stepping the movement was still quite jerky.
I decided that I needed some gearing to make the movement a little smoother.
Firstly I built a gear box using some plastic gears and mounted that in the
chassis. This worked ok, but the resulting motion appeared to be a little like
some sort of Victorian era steam powered invention. I think this is because
quite a lot of momentum builds up in the head as it turns, and because there are
gaps between the gears this causes a sort of 'buffeting' as the head gear
bounces off the motor gear. Of course this is magnified to the outer radius
of the head so it is quite noticeable.
As the 914 itself uses stepper motors to drive it's wheels, I took a hint
from the way the drive train has been designed and next I used a toothed timing
pulley and belt combination. This came out a little larger as the two pulleys
are further apart than the gears were, which unfortunately means that the
assembly occupies most of the top two drive bays at the rear of the Bot. I
relocated my
Buffalo Airstation wireless bridge to a slot behind my
Alphacool LCD
display at the front of the Bot, which is largely wasted space, to make space
for the larger size of the gearbox. The results from this drive train is much
better - it feels much more solid and there is much less slack when the head is
stationary.
I've also sorted out the stepper motor drivers which are each made from
Picaxe-18 high power project boards programmed to pulse the right stepper motor
phases and the correct time. I've also added a piggy-back board to one of the
project boards to take a spare output from the Picaxe to turn on some blue LEDs
mounted up in the head shell. Both drivers share an RS232 bus and are currently
connected to the mini-itx board's serial port. I can therefore command the
rotating motion for speed, direction and distance, as well as turn on and off
stepper motor holding power. The lifting stepper motor driver takes commands for
'up' and 'down' and deals with the blue LEDs which can be turned on and off at
will.
Watch this space in the next two days for a video of the mod in action!