Subject:
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Re: Wireless Robots
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Newsgroups:
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lugnet.robotics
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Date:
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Mon, 22 Nov 1999 13:22:10 GMT
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Viewed:
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753 times
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In lugnet.robotics, lego-robotics@crynwr.com (Pete Sevcik) writes:
> Matt,
> I have built a lego robot controlled by a PC, using an IR link to communicate
> commands. It used the same IR technology as Mindstorms, but had an
> omni-directional IR link on the robot. The problem is link speed. For • reliable
> communication, you need an error recovery protocol on the link. I designed a
> lightweight protocol, which worked well but added about 5 bytes of packet
> overhead. At 1200 baud, it takes too long to get data to the PC, and get the
> response back to the robot. e.g the sensor detects a wall, but by the time • you
> get that info to the PC, and get back a command to turn, you have already hit
> the wall. IRDA technology is faster, but the distance is limited to 3 feet.
> Radio links would be fine, but the low cost links are limited to about 1200
> baud.
>
> I was trying to do all the processing in the PC.
Would you consider making the RIS perform the check or just sending a verbatim
copy of what it gets to the sender (two way radio) and making the PC check that
the information was sent OK. I know that a bad packet from the RIS does then
not mean that the packet the RIS received from the PC was faulty.
But consider that a faulty packet repeated from the RIS, would triger the PC to
send a resend CMD (of some sort) thereby indicating that the following CMD is a
resend, in case the former was faulty. The case as is would be the RIS
spends time checking 100% of all packets received for error. While the PC would
be idling in a loop for most of the time. Whereas you could argue that having
the PC spend its computing power on a trivial task, and the RIS just forwarding
verbatim withthe PC listening for errors, using the method outlined above would
perhaps be a timesaver - if the RIS can output verbatim faster than it would
perform errorcheck.
> The technique might work if >you found a way to split the work.
> Do tasks that require a quick reaction time
> within the robot. Send the slower, more difficult tasks, back to the PC. If
> you use a video camera, send the video data as analog, directly to the PC.
Would it be posible to [gently] strip the radio link from a Cybermaster kit and
reuse them with the RIS?
My concern would be to semi quickly assemble the original Cybermaster again.
Should I need it.
I have no idea wether the radio stuff is integrated on the Cybermaster PCB, in
which case this is pretty much hitting a brick wall - pardon the pun.
Otherwise a performance identical setup would be possible to design (if someone
knows how) and implementable (for the few who have access to an electronics
wizard).
-breiler
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Message is in Reply To:
 | | Re: Wireless Robots
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| Matt, I have built a lego robot controlled by a PC, using an IR link to communicate commands. It used the same IR technology as Mindstorms, but had an omni-directional IR link on the robot. The problem is link speed. For reliable communication, you (...) (25 years ago, 21-Nov-99, to lugnet.robotics)
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