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Need some help with selecting the best method to interface wheel encoders to my — Parallax Forums

Need some help with selecting the best method to interface wheel encoders to my

MagnusMagnus Posts: 18
edited 2005-12-02 03:17 in General Discussion
Hi,
I have decided to add optical encoders to the wheels on my robot. I have been googeling for quite some time and it doesn't look that there is a standard way of doing this.

The frequences are not that extreme with 4 RPMs and 36 stripes on the encoder wheel we are talking about 300 ticks per second. But i need to poll four encoders to get the speed and direction of two wheels.

I have eveluated three deifferent approaches:

1. connect two optical encoders directly to the Javelin. While that might be possible i thing it will make it extremely hard to write the rest of the code and still beeing able to keep track of all pulses and time them.

2. Use my spare Basic Stamp (BS2E) as a separate counter/timer. This could be a possible way, but how do i interface the Javeling with the BS2 in a way that i don't loose any counts from the encoders.

3. Buy/build dedicated hardware to do the counting and timing. I'm no expert in designing circuits from scratch, but can anyone direct me to a solution or a chip that could help me do the job?

Any help or directions would p

Comments

  • Steve JoblinSteve Joblin Posts: 784
    edited 2005-11-10 01:43
    Check out the GMWW02 - Wheel Watcher Rotation Encoder for GM2/3/8/9 at http://www.solarbotics.com/

    There is also a version designed to work with a servo. You can see it here: http://www.nubotics.com/
  • MagnusMagnus Posts: 18
    edited 2005-11-10 09:46
    Interesting site. Since i allready have the encoders, the "WC-132 WheelCommander" could solve my problems if it is possible to interface with other encoders than theirs. Unfortunately it is not availible yet and it doesn't say how much it will cost.

    I wonder if something similar is possible to build arounf the BS2. Do you think it has enough power to do the counting and still handle some kind of serial communications? Controling the motors could probably be handeled by the Javelin.

    /Magnus
  • Steve JoblinSteve Joblin Posts: 784
    edited 2005-11-10 13:36
    Someone else is going to have to pick up the ball from here... I am way too much of a noob. Sorry I can't help... anyone?... anyone?... anyone?.....
  • Peter VerkaikPeter Verkaik Posts: 3,956
    edited 2005-11-10 15:34
    Repost your question on the robotics forum.
    I am sure they can help you.
    regards peter
    ·
  • Pete SkeggsPete Skeggs Posts: 2
    edited 2005-12-02 03:16
    Magnus,

    Check the site again. The WC-132 WheelCommander differential drive motion controller is now available.

    What resolution are your encoders?
  • Pete SkeggsPete Skeggs Posts: 2
    edited 2005-12-02 03:17
    Sorry -- I saw the resolution in your first post, after I made mine....
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