Subject:
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Re: Sword fighting robots
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Newsgroups:
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lugnet.robotics
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Date:
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Wed, 21 Aug 2002 22:07:18 GMT
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Original-From:
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Steve Baker <sjbaker1@airmail*IHateSpam*.net>
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Reply-To:
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sjbaker1@airmail.net#stopspam#
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Viewed:
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799 times
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Carl Kadie wrote:
> How can the two robots keep the right distance and orientation from each other?
I suppose you could use the IR transmitter and light sensor as a rangefinder.
Quite a few people have succeeded in getting range measurements using that
scheme. If the target is a known colour, that'll make it easier.
If the two robots take it in turns to rangefind - and are kind enough to tell
each other the answers they get then you could (in principle) put the range finding
mechanism off-center in each robot (say on their right hand sides). Hence, each
robot knows the range to it's opponent on the right side from it's own measurement
and the range on the left side from the information it's opponent sends it. Once
they get close enough for that ranging to work reasonably well, you'll get an
approximate idea of the orientations too.
> How can they move their swords precisely?
I doubt that they can - but sword fighting needn't depend on too much precision
providing you are measuring the moment of contact accurately. I would have thought
that a bump sensor mounted at the base of the sword (which would be hinged and held
in place with rubber bands) would detect when the sword had hit something.
Swinging the sword and stopping it dead when it hits something ought to be
reasonably convincing.
> We have two RXC 2.0's. 5 Lego motors (and one homemade one), two light
> sensors, 3 touch sensors, 2 light sensors, 1 angle sensor, 1 remote control.
> a good collection of regular Technic and regular Legos. If needed, I would
> buy more stuff for this project. I'm programming in NQC.
Perhaps you could figure out some mechanical arrangement in which starting
the robot moving forwards would *first* lunge the sword out forwards - and
only start to move the robot once the sword was fully extended. When reversing,
the motoer, the sword would first retract to the vertical - and when it reached
that position, the robot would engage it's wheels and drive backwards. You could
probably do that with a differential or a sliding worm gear. Then, short
bursts of motor power would lunge the sword around - and longer movements
would extend the sword and then start the robot driving in the same direction.
With two motors only, this arrangement could let you drive the robot forwards
and backwards *and* lunge and retract the sword all with just one motor -
and steer left/right *and* sweep the sword left and right with the other.
You'll need a differential adder/subtractor arrangement to have a simple
two-wheeled skid-steer drive that uses one motor for forwards/reverse and
the other for turning...there are lots of good designs on the web for those
things.
That would work out quite nicely since if you need to lunge, you'd first
extend the sword - and if that wasn't enough to make contact, the robot
would run forwards a bit. Similarly, if you needed to swing the sword
sideways and it didn't quite make it before hitting the limits or it's
travel, the robot would turn it's entire body to finish the manouver.
That leaves you an extra motor on each robot to do something else...parry
by rotating the sword to the horizontal position perhaps.
One light sensor should be enough for rangefinding - leaving you two sensors
for detecting the sword impact - perhaps two bump sensors, one for vertical
impact and one for horizontal.
I think the idea of swinging *and* lunging with the sword - and having the
robots 'put their whole bodies behind the move' when it's a big one - would
be visually more exciting.
----------------------------- Steve Baker -------------------------------
Mail : <sjbaker1@airmail.net> WorkMail: <sjbaker@link.com>
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Message is in Reply To:
 | | Sword fighting robots
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| IDEA: After watching the Tyron Powers version of Zorro, my 7-year-old son and I would like to make two Lego robots that can sword fight each other. To make it harder: They should be autonomous To make it easier: They should "cheat" by sending each (...) (22 years ago, 21-Aug-02, to lugnet.robotics)
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