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Subject: 
Re: optical mouse chips as vision sensors?
Newsgroups: 
lugnet.robotics
Date: 
Tue, 9 Jul 2002 03:02:08 GMT
Original-From: 
Mike Payson <mpayson@dawgdayzNOMORESPAM.com>
Viewed: 
1801 times
  
On Monday 08 July 2002 09:36 am, Steve Baker wrote:
> Laszlo Meszaros (ETH) wrote:
> > Keep in mind that the optical mouse chip detects skidding of the mouse
> > forward - backward - left - right. When fixed on the bottom of a lego
> > car it will never send signals about moving left and right. As fine as
> > I can emulate a lego car-like movement with my optical mouse it sends
> > only forward and backward movement signals.
> 
> Right - you only get translational motion - not rotation.  However, you
> could use two of these contraptions - on on each side of the robot (or one
> on the front and the other on the back) and thus derive the rotational
> speed from the difference in translational output from the two mouse chips.
> 
> I think you could also do this correctly with a single sensor (for a
> typical two-wheel-plus-caster/skid robot) if you mounted it far from the
> center of rotation of the robot.  Then, the lateral motion of the mouse
> chip would give you a pretty accurate idea of the rotational speed of your
> robot.

Hmmm... I don't see how that would work. How would a single sensor be able to
differentiate between rotational movement and straight forward & back
movement? I suppose you would be able to guess since you would know what
state the robot was in at any time (turning or straight), but it seems that
this would introduce a rather large margin of error. Or am I missing
something?

--
Mike Payson  |  DawgDayz Dog Walking & Pet Sitting
(206) 280-7295 | www.dawgdayz.com | mpayson@dawgdayz.com



Message has 2 Replies:
  Re: optical mouse chips as vision sensors?
 
Nevermind... I was assuming it would be mounted to the left or right of center (thus the rotation would still show up as forward or reverse). After thinking about it a moment, it occurs to me that by mounting the sensor in front of or behind the (...) (24 years ago, 9-Jul-02, to lugnet.robotics)
  Re: optical mouse chips as vision sensors?
 
(...) The mouse's camera chip tells you how fast the beast is moving forwards/backwards and how fast left/right - as two separate sets of numbers. If you mounted it on a boom (say) six inches ahead of the wheels of a typical two-wheel-plus-caster (...) (24 years ago, 9-Jul-02, to lugnet.robotics)

Message is in Reply To:
  Re: optical mouse chips as vision sensors?
 
(...) Right - you only get translational motion - not rotation. However, you could use two of these contraptions - on on each side of the robot (or one on the front and the other on the back) and thus derive the rotational speed from the difference (...) (24 years ago, 8-Jul-02, to lugnet.robotics)

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