Subject:
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Re: Brute Force Brick
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Newsgroups:
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lugnet.robotics
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Date:
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Tue, 16 Mar 2004 00:45:20 GMT
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Viewed:
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1193 times
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In lugnet.robotics, Steve Hassenplug wrote:
> Why? How many ports are needed? (either In or Out)
> What do you need to do that requires more than 10 inputs, or 5
> outputs?
Well, think about a top of the table fixed industrial machine, instead
of a bot moving around. LEGO technics offers great possibilities to
build such a prototype.
I have two incredible machines in mind:
The first one is a sorter for electronic resistors. The second one is
more incredible: a field of kitchen herbes is kept in an x-y array,
with a growth lamp illuminating them. It has a robot carring system
underneath it, that can move each plant to a support point, where it
gets water, the growth length is measured and so on. And carry it
back. I have build a wooden modell of it, with robots running on two
levels. On the highest is the plant.
These are phantasies only but i carry them in mind for a little
time. Meanwhile i find solutions for those problems and documentate
them. I dont know, if i will ever build it.
It would be nice, to have a BFB, at that you can expand input and
output. Then you can control the modell with a single BFB instead of
multiple RCXes (or BFBs), because these modells need the one more
sensor and motor line, than you offer.
Of course, i see, that building an expansion unit is not so
easy. First - if you ever do it - you must distinguish between an
input and an output (sensor and motor). Expansion ports have a fixed
function in this scenery. Meaning, they are either sensor or motor.
Because switching a port between a sensor and a motor is not a task
without problems. I see it. Hard to describe. The motor pins are at
the end of a H-bridge, while the sensor pins are polaried. What
happens, if you connect the motor output of an RCX to an sensor input
and drive the motor back and forth? Will the sensor input be blown?
Probably this is a one try opportunity: there might be diodes
perfoming a steady short circuit after beeing blown. Or not?
The question now is: if you dont want to build an
AnalogDigitalConverter (ADC) on each sensor expansion board and have a
digital conversation, how can you transmit analog data from the
sensors to the BFB? The most simple solution would be to reserve lines
for the analog signals. 6 more analog lines to extend 10 to 16 (a very
reasonable number, because it has binary boundage).
Analog lines on an expansion bus are one solution, the other one is a
complete digital interface. But this would require a microprocessor on
each expansion board. Making the thing quite expensive (additional
ADCs).
So future is not quite clear.
Talking about bandwidth limitation is a theoretical issue, if you only
sent byte messages between BFBs or RCXs.
Nevertheless ideas are growing with machines to realise them.
An example where bandwidth might be stressed: if the moving bots have
to exchange exessive amount of environment data. soccer playing bots
for example. In this case, one BFB for each bot would be enougth, a
hardware interconnection across the expansion bus between BFBs would
not help. But this would be the last open question remaining to make
the BFB a perfect world solution.
> My Jeep does 75 on the highway, and that's about as fast as traffic
> will allow me to go.
Take a trip to germany. In the land of the porsches, bmws and
mercedes, there is no speed limitation on the highways. Lease a
porsche and feel the freedom of driving as fast as the machine can
over hundreds of miles (germany is not as big as the us). In one day
you can cross germany with that machine.
Steering a car with full speed (a porsche will run at 250 km/h
continously), over hundreds of kilometers is an exiting thing.
1 statute mile = 1.60934 km
250 kmh / 1.60934 = 155.3 mph
Greetings
Ralph
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