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Subject: 
Re: moving in a straight line with two motors?
Newsgroups: 
lugnet.robotics
Date: 
Fri, 13 Nov 1998 16:19:21 GMT
Original-From: 
John Scott Kjellman <jkjellman@*AvoidSpam*ameritech.net>
Viewed: 
5106 times
  
Tim,

Instead of using the differential for angle sensors, why not use it to
allow a single motor to drive both wheels?  Then a single angle sensor
coupled with a motor could drive the steering mechanism.  This setup
would be very similar to a radio controlled car.

Just a thought.

KJohn

Tim Rueger wrote:
> 
> Hi,
> 
> One of the first things I ran into when making a mobile 'bot using one
> motor for each of two drive wheels was the mismatch in their speed.
> Needless to say, it's a nice way to make curved path.  Not what I want.
> 
> So I've got one of those nifty angle sensors.  I'd like to use it for
> feedback from the wheels to tell a motor to slow down when it gets too
> far ahead of the other one.  An obvious thing to do is to use two
> angle sensors and subtract them, but I'd like to do it with one sensor,
> given there are only 3 sensor inputs.
> 
> A simple mechanical way to do this is to use a differential gear,
> driving it backwards.  One input gets the rotation of one wheel, and
> the other input gets an inverted rotation of the other wheel.  With
> equal wheel rotations, there is no movement of the differential
> housing.
> 
> Unfortunately, gear slop keeps this from working well for me.  Any
> suggestions?
> 
> Thanks,
> -Tim
> 
> --
> Tim and/or Shelley Rueger - rueger "at" io.com
> WWW page: http://www.io.com/~rueger/



Message has 2 Replies:
  Re: moving in a straight line with two motors?
 
(...) At one point, in the distant past, I saw plans for a gear box that used either 2 or 3 differentials, I do not remember which. 2 motors were used, 1 to drive both axles, one for steering. axle1 == motor1 + motor2 axle2 == motor1 - motor2 With (...) (28 years ago, 13-Nov-98, to lugnet.robotics)
  Re: moving in a straight line with two motors?
 
(...) The problem with this is that you now have a car-style turning radius (determined by front wheel deflection and traction) instead of a tank-style turning radius (essentially zero). Daniel "Dan'l" Miller Senior, School of Aeronautics and (...) (28 years ago, 13-Nov-98, to lugnet.robotics)

Message is in Reply To:
  moving in a straight line with two motors?
 
Hi, One of the first things I ran into when making a mobile 'bot using one motor for each of two drive wheels was the mismatch in their speed. Needless to say, it's a nice way to make curved path. Not what I want. So I've got one of those nifty (...) (28 years ago, 13-Nov-98, to lugnet.robotics)

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