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Subject: 
Re: robotic rovers
Newsgroups: 
lugnet.robotics
Date: 
Mon, 30 Aug 1999 23:49:57 GMT
Reply-To: 
nospam-dcchen@pacbell.net-nospamAVOIDSPAM
Viewed: 
1811 times
  
I wrote:
> > I have also figured that if you connect the two motors to each other (as
> > well as to their respective outputs), you should lock in their movements
> > together.  Perhaps you could run this thru a interrupter switch to shut
> > off this connection while turning. • To which you wrote:
> Well, I was with you up to this point...  I don't understand exactly what
> you're suggesting here. • Then he wrote: (much more concisely)
> I think what David meant with the phrase "lock in their movements together" is
> the incorporation of an electronic or mechanical device that will connect the
> respective wheel outputs so that the robot travels in an absolutely straight
> line...<snip>

It could work in theory, but I just tested it again with 2 motors that
were grossly mismatched.  Having both motors interconnected
(electrically) did NOT cause their respective torques to match up as I
had hoped.  I think the key would be in a mechanical lockup between the
two axles.

I had thought of one that could work, but haven't applied it yet.  It
goes like this:

Given an AB steering system (ie. each side controlled by a separate
motor).

Wheel A <---- Motor A ----> Differential <(inverted)- Motor B ---->
Wheel B
   ^
Clutch  (that can lock up this Differential)
   +-----Motor C

1) When going straight, the clutch is locked to the differential case
preventing it from rotating and effectively locking A in step with B.
2) Before turning, dis-engage the Clutch with Motor C, now A and B turn
independently.
3) Do your turn.
4) Re-engage the clutch before going straight.
5) Go straight.

Sure it ties up an extra output, but you now have synched outputs at
will.

Eh?
Dave



Message has 1 Reply:
  Re: robotic rovers
 
It sounds like you guys are trying to re-invent the adder/subtractor system. Check out (URL) for some designs using this. In an adder/subtractor you have two motors, A and B. The wheels are then run through a mechanical linkage such that one wheel (...) (27 years ago, 31-Aug-99, to lugnet.robotics)

Message is in Reply To:
  Re: robotic rovers
 
Steve, I think your post was meant to read like this: (...) I was working with this same idea yesterday, but the problem is this will not give you correct information when you are turning. Does anyone have a suggestion about how to do that? I want (...) (27 years ago, 30-Aug-99, to lugnet.robotics)

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