Subject:
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Re: Brainstorms
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Newsgroups:
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lugnet.robotics
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Date:
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Sat, 10 Aug 2002 16:29:14 GMT
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Viewed:
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789 times
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All:
I think the project that I am working, called RoboBricks,
on is quite relevant to this topic.
Since this is my first post to this group, I should introduce
myself as a very active member of the Home Brew Robitics Club
based out of San Jose, California. Bill Benson (another HBRC
member) and I concluded that we needed a more modular robotics
platform to enable some of the more sophisticated robots that
we were thinking of building. After evaluating our options,
we concluded that we were going to have to roll our own modules.
Hence, the birth of the RoboBricks project. There is a rather
non-flashy project page located at:
http://web.gramlich.net/projects/robobricks/index.html
Since microcontrollers are so cheap, we decided to put a
dedicated microcontroller on each module. Thus, our servo
module will keep the servo pulses flowing as you focus on
providing the higher level robot behavior. Likewise, our
shaft encoder board will keep track of the shaft position
while the central machine is mulling over some particularly
complicated bit of behavior.
We standardized around a 4-wire polarized connector that
provides power, ground, serial-up, and serial-down. In
a pinch this could be simplified to a 3-wire connector.
Communication occurs at 2400 baud using 8N1 (8 data bits,
no parity, and 1 stop bit) using standard "TTL" signaling
levels. Going down to 2 wires would be quite difficult
though. These modules can be arranged in a tree-like manor
to provide extensive sensor/actuator robot networks.
Oh, yeah, we made sure that each RoboBrick printed circuit
board has 4 holes across the top and bottom that exactly
fit and line up with the studs of a standard Lego brick.
We did *not* standardize on a central processor. Instead,
we let the user choose among a variety of processors.
One of our boards uses a PIC16F876 and another uses a
Basic-Stamp 2 from Parallax. Any chip that is pin compatible
with the Basic Stamp 2 can plug into our BS2Hub8 board.
There are now 3 or 4 pin BS2 pin compatibles including at least
one that uses Java as its native language. Longer term we
expect there to be a total glut of inexpensive old PDA's
(e.g. old Palm Pilots) on EBay that will take over the job of
central behavior.
The current status is that we are running an "alpha" where
about 20 members of the HBRC (Home Brew Robotics Club) are
going to build and use a small initial set of modules.
Once we have some happy customers, we are going to open
the availability up to a wider audience. I expect the
"alpha" will be winding down near the end of September.
The actual parts cost of these RoboBrick modules is
quite low. The board plus parts cost tends to range
from $5-$10 each. In fact, for most RoboBrick modules,
the printed circuit board is one of the most expensive
parts; the PCB board price will ramp down as we get
some volume up.
With that brief introduction to myself and RoboBricks,
I'll be quiet now and let people ask any follow up
questions.
Thank you,
-Wayne
In lugnet.robotics, John Barnes writes:
> Ok. I've seen a similar ebb and flow of ideas for modularization in this
> newsgroup before. The difference, is that now, most people who are reading
> this a probably well familiar with the RCX, Mindstorms, etc etc.
>
> The subject of this post is intended as an invitation to anyone who would
> like to contribute their ideas, wants, wishes, desires for a new direction
> for managing a microcomputer controlled Lego creation. As far as I see it
> there are only two real candidate architectures, modular and monolithic. I
> regard the RCX as a monolithic structure in the sense that is the entire
> core entity into which you plug motors and sensors. A modular approach, in
> this context, would split that monolithic central "thing" into a number of
> constituent entities, like power source, CPU, memory, sound making devices,
> displays etc etc.
>
> Modular?
>
> How do you connect them? By wires? By plugging modules together?
> What sort of granularity is required? All semi-intelligent? One master with
> loads of dumb I/O slaves?
> How do you supply power to all the modules? Independently? Along the common
> data communication interface (via the wires or plugging scheme mentioned above)?
> How does your software deal with the variable topology possible? Do modules
> somehow use some kind of dynamic address assignment(how does your software
> know which motor controller is which?)? Do modules have preset addresses or
> IDs (do you really like those fiddly little DIP switches?)? Or do you have
> some kind of initialization process to give them an ID they store internally
> in EEPROM (in which case they all look the same, and you have to try and
> remember what ID you programmed into each one to be able to talk to it again?)?
>
> etc ... etc ... etc
>
> Monolithic?
>
> Do you want a bigger RCX? How big - 6 motors/12 sensors?
> Assuming it uses 2x2 Lego style connectors, can it have connection studs on;
> just one face (top?)?, two faces (top and bottom to make it smaller? but
> harder to build into a model!)?
> Internal or external batteries/power?
> How much memory?
> Does it need a display? What sort?
> Does it need buttons? How many?
> Does it need both IR and RF comms?
> Does it need to be able to comm with other ones of its own kind?
>
> Please let your imagination wander and contribute your thoughts. Just
> remember to keep practicality in the back of your mind when blue-skying
> this. I may well decide to build a sample or two of what comes out of this,
> assuming something does. So it needs to be able to be done with existing
> commonplace technology.
>
> JB
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Message has 4 Replies:
 | | RE: Brainstorms
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| Wayne wrote (in his first post no less!) (...) <snip> (...) <snip> This is more like it. I've snipped out the juicy bits on the serial comms channel and modular power connector. The comms channel sounds a bit slow, but then again the fire alarm (...) (22 years ago, 10-Aug-02, to lugnet.robotics)
| | | RE: Brainstorms
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| Wayne, In the spec you indicate that each brick gets its own 128 bit random number. This is like a serial number that is initially use to uniquely identify each brick with a shorter BrickID. This is a common technique in fire alarm systems where (...) (22 years ago, 10-Aug-02, to lugnet.robotics)
| | | Re: Brainstorms
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| (...) the interconnect protocol is run so slowly. Why only 2400 baud? Anything where you have an actual copper wire connection could run orders of magnitude faster. Heck even iRDA goes faster over infraRed. ---...--- Steve Baker ---...--- Mail : (...) (22 years ago, 10-Aug-02, to lugnet.robotics)
| | | Re: Brainstorms
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| hi Fred, I would love to see a reaction from you on the discussion in this thread in lugnet.robotics. Not only because you're the inventor of the RCX but also you've done some some similar things, creating modular, stackable electronics with the aim (...) (22 years ago, 12-Aug-02, to lugnet.robotics)
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Message is in Reply To:
| | Brainstorms
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| Ok. I've seen a similar ebb and flow of ideas for modularization in this newsgroup before. The difference, is that now, most people who are reading this a probably well familiar with the RCX, Mindstorms, etc etc. The subject of this post is intended (...) (22 years ago, 8-Aug-02, to lugnet.robotics)
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