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Subject: 
Re: Communication between the RCX and the Cybermaster
Newsgroups: 
lugnet.robotics
Date: 
Wed, 23 Aug 2000 04:57:51 GMT
Viewed: 
823 times
  
Jon Kongsvold wrote:

I am thinking of making a teleoperated autonomous robot which I can give
orders through the radio tower of the Cybermaster.  These orders will be
like "find a thing and pick it up", "drop down whatever you are carrying",
"tell me the color of whatever you are carrying" etc.  These messages should
then be sent to one or two RCXes that autonomously finds a way to solve the
problem and sends a message to the Cybermaster and then back to the
controlling PC, which then can send a new order to the Cybermaster.  Sort of
like the Mars Sojourner, you tell it to go somewhere to pick up and analyze
whatever is in that area etc, and the robot figures out how to do it by
itself.

The first problem I need to solve is to get the radio messages from the
Cybermaster to the RCX(es) that are the real brain of the robot.  The
Cybermaster should only be used as a base for moving the robot and
communicating with the PC, while the RCX(es) do all the "thinking" and
controls (at least) a robot arm, a "science station", for example measuring
color, temperature, weight (maybe possible using a rotation sensor for
calculating the weight...?) of the whatever it's carrying.

My first idea on how to solve this communication problem, is to make sort of
a telegraph sending and receiving messages from and to the Cybermaster and
the RCX.  Using one motor on each pbrick to push a touch sensor on the other
pbrick, I should be able to send signals between them (or maybe light
sensors and lamps are quicker than the motor solution?).  To make this work
I need to make my own communication protocol for this telegraph.  Have
anyone done this before?  Or maybe someone have some good tips for me on how
to implement the telegraph's communication protocol to make it as fast as
possible.  I fear that this telegraph will send and receive binary messages
between the pbricks horribly slow, haven't got a clue on how good bps-rate I
can get using this morse-like way of communicating between the pbricks.

Any ideas on what to put into my "science station" (it will be onboard the
robot) are also of interest, I want the robot to be able to find out as many
facts of the thing it is carrying as possible.  So if you have any ideas of
other things I can measure using my LEGO sensors (got a total of 9 touch, 5
rotation (including the 3 tachometers in the Cybermaster), one temperature
and 3 light sensors, which can send their input to the Cybermaster or two
RCXes), which should be used to find out a lot about the robot's position
and other movement related info and many different facts of the samples it
is picking up and analyzing.

I would recommend the CM talking to one RCX that then can use standard IR to
talk to the other(s).

I've been thinking of this for awhile now. I don't yet own a CM so I'm just
guessing that it has similar 'codes' (1 - 255) like the RCX.

I would put the single CM's motor port onto the Main RCX's Input.  Then do the
reverse to the CM from the RCX. From the RCX to the CM it is easy. Simply toggle
the Motor output from OFF to FLOAT. Since OFF shorts the output it's EXACTLY
like having a Switch flip on and off.  I BELIEVE the CM works the same way, but
can not confirm. If not you will need a fast relay if the input port can't
handle 8volts.

Using modes such as PULSE or EDGE you should be able to count and create a
command set.

If you would like to discuss this more, please contact me.

Dean
--
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Vancouver Lego Club: http://www.akasa.bc.ca/vlc



Message is in Reply To:
  Communication between the RCX and the Cybermaster
 
I am thinking of making a teleoperated autonomous robot which I can give orders through the radio tower of the Cybermaster. These orders will be like "find a thing and pick it up", "drop down whatever you are carrying", "tell me the color of (...) (24 years ago, 19-Aug-00, to lugnet.robotics)

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