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Subject: 
Re: Dead reckoning (was Re: Rover Programming)
Newsgroups: 
lugnet.robotics
Date: 
Fri, 28 Jun 2002 15:55:43 GMT
Original-From: 
Jona <jjeffords@!spamcake!ameritech.net>
Viewed: 
1068 times
  
Hi Simon,

In my experience casters can introduce errors in the navigation since they
tend to not be in the correct position following a turn. Over time this
small error can add up. I have had some success by rebuilding my bot to
center as much of the weight of the bot over the drive axle, and then using
a skid plate instead of a caster. The centralized weight allows the wheels
to bear the burden, and the skid plate only actually touches the ground for
split seconds at a time when there is a change in momentum.

If you find you are still having some problems with your current setup, you
may consider losing the casters.

Jona

----- Original Message -----
From: "Simon Brooke" <simon@jasmine.org.uk>
To: <sjbaker1@airmail.net>; <lego-robotics@crynwr.com>
Sent: Friday, June 28, 2002 4:30 AM
Subject: Re: Dead reckoning (was Re: Rover Programming)


On Friday 28 Jun 2002 8:27 am, you wrote:
Simon Brooke wrote:
So I'm now looking at software solutions that reduce inertia - i.e.
gradually ramping up and down speed in turns. We'll see how this
goes.

Yes - managing accelleration is a 'must'...both in speeding up and
slowing down - and easing into turns.  An abrupt change of speed will
generally result in wheel slip.

Well, I did the code changes to do acceleration and deceleration
yesterday and it's amazingly successful. I'm not yet quite as good as
the Seattle robot, but I suspect that's at least partly because mine
has a narrower track. I now believe that, with tweaks to the robot and
the code, I can get down to 1% error.

I'm *very* encouraged.

The two-large-wheels-plus-caster(s) seems to be the undesputed best
design for navigation (at least with Lego parts).

Oh, well, I'm currently using two large wheels plus two casters, so I'm
probably OK.

Cheers

Simon

--
simon@jasmine.org.uk (Simon Brooke) http://www.jasmine.org.uk/~simon/

;; when in the shit, the wise man plants courgettes



Message is in Reply To:
  Re: Dead reckoning (was Re: Rover Programming)
 
(...) Well, I did the code changes to do acceleration and deceleration yesterday and it's amazingly successful. I'm not yet quite as good as the Seattle robot, but I suspect that's at least partly because mine has a narrower track. I now believe (...) (22 years ago, 28-Jun-02, to lugnet.robotics)

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