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Subject: 
Re: Adder/Subtractor revisited
Newsgroups: 
lugnet.robotics
Date: 
Tue, 2 Feb 1999 13:03:17 GMT
Viewed: 
1028 times
  
Cyberia wrote:

This is not what we did with our models.

In the method we, and others have used, you apply the motor power to the
carriers of the differentials. There are two possible places to apply the
drive force to each carrier (24 teeth or 16 teeth). You do not have to use
the same one for each carrier, this permits you some degree of control of
the steering ratio.

The output shafts can drive wheels directly or through reduction, or tracks
through some serious reduction.
Tracks require more torque, particularly when turning. Although the A-S
transmission seems ideal in this respect, the single motor for
forward/reverse requires toom much reduction to be useful (unless your bot
is not in a hurry).

Right. This is what I was trying to get at. If one motor gives too
little power, you can add the power of two together trough a
differential. Power the axles of the differential by two different
motors, and the added power comes out through the body. If you want to,
you could of course use that power to drive an adder-subtractor
construction. In that case you'd need three differentials.

You need the extra differential to add the power of two motors, because
they don't always rotate at exactly the same speed.

Regards,

Johannes.



Message has 3 Replies:
  Re: Adder/Subtractor revisited
 
Ahh, I see. I thought you meant to power the primary diff in the A-S transmission in this fashion. Yes, a third diff coupled carrier-to-carrier with the primary one in the A-S would work. Three diffs ! I don't think I have enough of them to model (...) (25 years ago, 3-Feb-99, to lugnet.robotics)
  Re: Adder/Subtractor revisited
 
(...) I can understand why you'd need a method like this if the two motors were radically different types, but if you're dealing with two identical motors (such as the 9V MindStorms motors), is this really necessary? The tolerances may be a teensy (...) (25 years ago, 4-Feb-99, to lugnet.robotics)
  Re: Adder/Subtractor revisited
 
In article <36B6F795.4B9310A6@n...a.kth.se>, johannes@nada.kth.se says... (...) Ingenious as it is, this thread and previous similar ones have pointed out the primary problems with the A-S drive approach: power transmission through the LEGO (...) (25 years ago, 6-Feb-99, to lugnet.robotics)

Message is in Reply To:
  Re: Adder/Subtractor revisited
 
This is not what we did with our models. In the method we, and others have used, you apply the motor power to the carriers of the differentials. There are two possible places to apply the drive force to each carrier (24 teeth or 16 teeth). You do (...) (25 years ago, 1-Feb-99, to lugnet.robotics)

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