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Subject: 
Re: Tachocount
Newsgroups: 
lugnet.robotics
Date: 
Thu, 12 Nov 1998 16:59:05 GMT
Original-From: 
Laurentino Martins <LMARTINS@MARKTEST.nospamPT>
Viewed: 
2445 times
  
Do you think a tachometer needs to distinguish direction? Why?

Going forward or not, a vehicle _moves_ from one place to the other, so the space moved must always be added, never subtracted.
How could you otherwise figure _how_much_distance_ you traveled if sometimes it added and sometimes subtracted???

Have you ever seen a car were when the distance counter starts counting backwards when it reverses direction?

Laurentino Martins

--//--

At 16:38 12-11-1998 Thursday , you wrote:
"Eric Brok" <brok@fcjsvc.hvu.nl> writes:

I fiddled a liitle with it, but it doesn't seem too useful, first of
all because the internal motors are only practical to use for wheels

I'm sure the motors may be used for other things as well, albeit not as
easily as separate motors.

and second because the tachocounter doensn't distinguish direction.

But in a program you will always know which way the motors drive, right?
So one can possibly maintain a second variable for each motor that is
updated every time the motor changes direction.  That way, it may be
possible to keep track of the distance travelled.

So you can only use it as a feedback input while the motor is driven
by the program, so you know the direction. I used such a feedback
loop to make my Crusher walk a little straighter

This sounds useful enough for me.

The speed and torque of the motors also appeal to me.  The new 9V geared
motor almost always needs to be geared down anyway, so it's a good thing
that the Cybermaster motors have a somewhat slower pace.  (I still
haven't used them that much, though, but that's mostly due to the fact
that I don't have a computer at home.)

Fredrik



Message has 2 Replies:
  Re: Tachocount
 
(...) I think we need to think of other applications than cars as well. The tachometer can be useful in a lot of other mechanisms. Suppose we have a 2D plotter set up, and use one motor for the x coordinate and one for the y. That way, tachometers (...) (26 years ago, 12-Nov-98, to lugnet.robotics)
  Re: Tachocount
 
Good point of view, but I think that the intention of LEGO when created CyberMaster was to make vehicles. From that point of view it is a great bonus to have some tacho counters, since a toy car don't need them very much (but maybe Crusher needs (...) (26 years ago, 12-Nov-98, to lugnet.robotics)

Message is in Reply To:
  Tachocount
 
According to the Technical Reference, Tachocount counts the number of revolutions of the motor shafts (of the two built-in Cybermaster motors ONLY). I fiddled a liitle with it, but it doesn't seem too useful, first of all because the internal motors (...) (26 years ago, 11-Nov-98, to lugnet.robotics)

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