Subject:
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Re: SSClagorpion
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Newsgroups:
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lugnet.technic
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Date:
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Tue, 20 Apr 2004 21:01:21 GMT
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Viewed:
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9612 times
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In lugnet.technic, Kevin L. Clague wrote:
> In lugnet.technic, Steve Hassenplug wrote:
> > > Hmmm.... We would need to know two things to determine we'd hit the edge of the
> > > table.
> > >
> > > 1. The foot is down as far as it will go.
> > > 2. The down foot is not touching anything.
> > >
> > > We would need one of these sensor pairs for each front foot.
> >
> >
> > Right. That's listed somewhere in my prior ramblings. It should work fine with
> > 2 inputs (one for each foot)
>
> OK. You are going to put two touch sensors on one port?
>
> I thought you needed to know that the leg is fully extended, but not touching.
> How will you do that with one sensor port?
There are a couple ways that come to mind. If you don't want to know the
details, skip ahead...
We want to know when the leg is extended, and the foot is not touching the
ground.
There will be four possible states:
1) Leg up, foot not touching ground
2) Leg extended, foot not touching ground
3) Leg up, foot touching ground
4) Leg extended, foot touching ground
The first thing to remember is that when the foot IS touching the ground, it
doesn't matter if the leg is extended. (that's the key to making it easy)
So, there's only three usable states. The "foot" sensor can override the
reading from the "leg" sensor.
If you connect a light sensor to look at the leg/knee joint, so it reads white
when the leg is extended, and grey or black when it's in other places, then you
can also connect the foot touch sensor to the same port.
When the foot sensor is "open" the RCX will read values from the light sensor,
so it can actually calculate the exact location of the leg/joint. When the foot
sensor is "closed" it can assume the foot is on the ground, so the leg must be
extended.
You could also do something like that with two touch sensors, and a couple
lights. I have even more ideas, but I think the light/touch combination would
be the best, and most "stock LEGO" approach.
> > If I understand this correctly, when he puts his other four feet down, and
> > senses one foot is off the table, he must continue walking forward, raising four
> > feet from the table, and leaving him standing on three feet, including NO front
> > feet.
> >
> > That makes me think we'll have to consider weight distribution, and how it will
> > balance on three feet.
>
> You are right, he needs to balance on the three feet that are further back, but
> it will not have to walk forward. It can walk backwards.
Well, it will walk forward enough to lift the other four feet off the ground,
before it starts backward, again.
I'm going to have to look at the walking logic more to understand why it can't
start walking backward, while all the feet are on the ground.
So, we'll need to make sure the center of gravity is closer to the third set of
legs, and it CAN'T be in front of the second set.
I hope Eric's listening. :)
Steve
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Message has 2 Replies:
 | | Re: SSClagorpion
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| In lugnet.technic, Steve Hassenplug wrote: <snip> (...) Nope. The sequence is: 1. All feet down. 2. Lift one foot group 3. Sweep legs 4. put feet down 5. Lift other foot group 6. Sweep legs So it does not need to walk forward to lift the feet. (...) (...) (20 years ago, 20-Apr-04, to lugnet.technic)
| | | Re: SSClagorpion
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| (...) Ahem, (...) So we can incorporate the tail's funtionality and weight to help aid the robot by swinging or uncurling the tail so it faces away from the body and is extended back. This shifts the center of gravity away from the front of the (...) (20 years ago, 21-Apr-04, to lugnet.technic)
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Message is in Reply To:
| | Re: SSClagorpion
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| (...) OK. You are going to put two touch sensors on one port? I thought you needed to know that the leg is fully extended, but not touching. How will you do that with one sensor port? (...) You are right, he needs to balance on the three feet that (...) (20 years ago, 20-Apr-04, to lugnet.technic)
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