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 Robotics / RCX / legOS / 3906
3905  |  3907
Subject: 
Re: position calculating for robots
Newsgroups: 
lugnet.robotics.rcx.legos
Date: 
Thu, 26 May 2005 19:47:38 GMT
Viewed: 
7469 times
  
In lugnet.robotics.rcx.legos, John Hambas wrote:
Thanks Thomas for your idea. The matter is that I was thinking of using angle
sensors in order to calculate the number of the turns that each wheel has driven
(I am talking for a robot with 2 wheels). I think that some advanced maths are
required for such thing but iam not sure. Does anyone knows if lejOS is more
powerful that BrickOS in maths? Has anyone tried something like that?

P.S. Alan from Australia, I accidentaly erased your e-mail. Contact me again

From something I read 12 years ago for my university project (a Lego robot of
course, but pre-RCX), I think it required differential equations (ugh!).
Probably a bit too memory-hungry for an RCX.  Perhaps you could use the PC's
computing power and send 2-way messages.  That's why I wanted a radio interface
for the RCX.  You could always try with a Cybermaster though - two built-in
shaft encoders and RC comms.

An alternative would be to build the robot differently - make one motor do the
forward and backward motion and the other do the spinning, with differential
gears adding and subtracting the two motor movements for each wheel.  Combining
the two motor movements will do a turn, the radius varying with the speed of the
two motors.  This method means that the robot has better straight-line travel,
since it depends on the speed of one motor for both wheels.  You can also gear
down the turning motor to get more accurate turning.

Measure the rotation of the forward motor for distance and that of the turning
motor for angle, then plot your course like a ship, with an amount of travel on
a bearing.  The maths for this should be simpler, allowing an RCX to do it.

Mark



Message has 1 Reply:
  Re: position calculating for robots
 
(...) There are various geometries have been implemented in Lego bricks for this. Here is one example: (URL) searching Google for "Lego adder subtractor" for others. (19 years ago, 2-Jun-05, to lugnet.robotics.rcx.legos)

Message is in Reply To:
  position calculating for robots
 
Thanks Thomas for your idea. The matter is that I was thinking of using angle sensors in order to calculate the number of the turns that each wheel has driven (I am talking for a robot with 2 wheels). I think that some advanced maths are required (...) (19 years ago, 26-May-05, to lugnet.robotics.rcx.legos)

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