Subject:
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Re: Homing with the IR Tower
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Newsgroups:
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lugnet.robotics
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Date:
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Tue, 27 Jul 1999 19:28:08 GMT
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Viewed:
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1073 times
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> I believe that tracks (or wheels coupled to behave like tracks) are a poor
> choice to get good results from odometry. I mean, as this mechanical
> arrangement relies on slippage to turn, it's unprecise for its own nature.
> IMO a differential drive is much more suitable to get the best from odometry.
My first thought: If you don't connect the tachometers directly to the tracks,
but to the separate, unpowered wheels, you don't have to care if the tracks
slip or not.
My second thought: When the robot turns, there is exactly one "fixed point"
(i.e., the point without slippage) on each of its tracks. Unless the
tachometer wheels are exactly on the same line as these two fixed points,
minor slippage on the tachometer wheels may still occur.
So yes, the differential drive with two driven wheels is more accurate than
tracks.
The problem is: It tilts easily when the claw lifts the can.
The robot goes out looking for cans, grabs one, then heads home. Hopefully, we
don't have to care whether it does its tasks in straight lines or not.
> I have another idea about using the Dennis Clark's IRPD to detect cans: we can
> turn it 90 degrees so the left and right detectors are on the same vertical
> line and become "bottom" and "top" detectors. Placing the sensor at the proper
> height on the bot, we should be able to tell if an obstacle is a wall (bottom
> detection only) or a can (bottom and top detection at the same time).
> Obviously I assume that the walls are higher than the cans :-)
One nice thing about IRPD is that you get two detectors in one input port.
> Hope this may help your project. I'll start mine sooner or later :-)
Thanks. Since the initial release of Mindstorms, the Recycler has been
pictured on the lid of the box. Isn't it a bit surprising that so much is
involved to make it actually working?
Cheers,
Hao-yang Wang
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Message has 1 Reply:
 | | Re: Homing with the IR Tower
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| (...) You can add more free wheels to make it very stable. (...) When I approached the Joel's challenge I was worried also about the time to collect the cans. My idea was to develop a reliable navigation system to minimize the time to find the cans. (...) (25 years ago, 28-Jul-99, to lugnet.robotics)
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Message is in Reply To:
| | Re: Homing with the IR Tower
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| (...) I'm intrigued too by Joel's challenge. This was the reason for I started my experiments with odometry months ago. The problem is always the same: much more projects in mind than time to carry them out :-) <snip!> (...) motors, (...) are (...) (...) (25 years ago, 27-Jul-99, to lugnet.robotics)
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