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One More Stupid Question, Please. . .about the servos. — Parallax Forums

One More Stupid Question, Please. . .about the servos.

MovieMakerMovieMaker Posts: 502
edited 2008-11-04 21:02 in BASIC Stamp
I put the first boe-bot together fine. No real problems. When I put the second one together, I thought it was going to be easier.·

Well, I found out the the florescent bulbs in my house have fixed it were I will NEVER be able to use IR for detection. This was not good. But, I said "ok."· You have to learn to accept things you cannot change. Until I move into another house (unlikely), I am stuck with this fact.

Moving right along, I cannot get the datalogger to work properly. But, I still have some more sugestions from this forum to try. So, I am still optimistic on this one.

But, When I pulse my Pingservo, it just goes to one location and vibrates.· And when I tell the bot to go forward, it runs right servo forward and left servo backwards. I guess I could plot out the exact points on the servo and change them, but what have I done wrong?· I wired all of this up the same.· I probably made a mistake. But, I have read hundreds of books and everything is getting out of focus now.·

This is my brain . . . . This is my brain on Bots. .......

No, seriously, I am probably doing something wrong.

Thanks for letting me bend your ear to listen to my stupid question.

I have BIG plans for both bots, but I am having problems just getting them to do the standard stuff.

Thanks,

[noparse]:)[/noparse]

Comments

  • allanlane5allanlane5 Posts: 3,815
    edited 2008-11-02 02:22
    Well, the mechanics of the situation are that in order for the BOE bot to move forward, the servo's have to turn in opposite directions.

    You see, the instructions have you mount the servo's in "mirror image" to each other on the BOE Bot. So, to have them both turn "forward", you have to command one to turn "left" while the other turns "right".

    This is one of those really un-obvious things that happens early on. You'll get it.
  • MovieMakerMovieMaker Posts: 502
    edited 2008-11-02 02:30
    Does that mean I installed them backwards?
  • Mike GreenMike Green Posts: 23,101
    edited 2008-11-02 02:45
    You installed them correctly. They are normally installed "backwards" from each other.
  • allanlane5allanlane5 Posts: 3,815
    edited 2008-11-03 00:38
    Nope, you installed them properly. It's proper installation that one has to turn "left" while the other turns "right" in order to move "forward".
  • MovieMakerMovieMaker Posts: 502
    edited 2008-11-03 14:26
    Well, the wheels are turning in oposite directions and the machine goes in circles.
  • JonathanJonathan Posts: 1,023
    edited 2008-11-03 15:05
    MM,

    Have you adjusted the servos to set the "zero point"? If you send a 1500uS pulse to the servos, do they both stop? If they are both moving forward, but one is moving faster than the other, the bot will do a slow circle.

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  • allanlane5allanlane5 Posts: 3,815
    edited 2008-11-03 16:27
    If the machine "goes in circles", then it's likely both wheels are turning on their servo's in the same direction.

    Pick up the Bot. Turn the Bot so you're looking at the right side, with the front of the bot pointing to your right.

    See, if you look at the right side of the Bot, in order to turn "forward" (clockwise), the servo has to rotate to the right.

    Now, turn the bot so you're looking at the LEFT side, with the front of the bot pointing to your left.

    If you look at the LEFT side of the bot, in order to turn "forward" (counter-clockwise, because you're looking at the LEFT side now) the servo has to rotate to the LEFT.

    Thus, you can't use the same number for the right servo as the left servo. If you do, both wheels will spin "in the same direction" (both right, or both left) and the bot will rotate in a circle.
  • MovieMakerMovieMaker Posts: 502
    edited 2008-11-03 20:20
    Thank You guys for your suggestions.· I will try when I get home from work. I believe that the servos that came with the bot do not have adjustments on them. The plastic is sealed. Am I supposed to drill a hole in order to adjust?

    If I remember correctly to center them, I gave them a 750 .



    ·
  • SRLMSRLM Posts: 5,045
    edited 2008-11-03 22:36
    The Parallax servos have a little cross head screw through the casing under the wire. Mine are blue and yellow.
  • MovieMakerMovieMaker Posts: 502
    edited 2008-11-04 02:02
    Thanks, I have some more honeydos to do. It'll have to be later. But, I will keep you informed.
  • MovieMakerMovieMaker Posts: 502
    edited 2008-11-04 21:02
    I finally found the servo adjustments. I saw them on the orginal servos of the first robot,but on the second one, they were not where I could see them easily. But, when I checked back, there they were. So, now I can run the tests if I can just get home from work and have time to do it.
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