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Robot Efficiency & other Robot stuff

Discussion in 'Robotics & Mechatronics' started by williB, Oct 6, 2004.

  1. williB

    williB New Member

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    would it be possible to store the energy from the reverse EMF of a stepper, as it is running.
    i was just wondering if i could save power in battery powered robot with a very large electrolytic capacitor connected across the main power supply.
     
  2. Optikon

    Optikon New Member

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    Re: Robot Efficiency

    yes, one form of it is called regenerative braking. A capacitor across mains supply will not save any power. Capacitors just store energy.
    To make the system effective, you will have to get that energy back into the battery. When the vehicle is moving but the drive is not driving the motors, the motors can act like generators and that energy can be recovered but it is more complicated than just using a capacitor.
     
  3. williB

    williB New Member

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    ok but when u turn off a coil in the stepper,, and redirect the back EMF with diodes twards the positive supply terminal,, where does it go..
    i can only assume that it is stored in the powersupply caps..
    so that is what i had in mind with the battery setup..
     
  4. dave

    Dave New Member

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  5. williB

    williB New Member

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    Ive just got my robot moving for the first time..last night..
    i am using two steppers ,one for each back wheel.
    the two steppers are connected together..ie driven by the same drive transistors..i will drive them seperately after i get four more IRF 510's
    i realized thet i had to run the second one in reverse so i made the proper connections
    something very strange happened ..
    When all power was off and i turned one wheel ..the other wheel turned in the same direction..!!
    so i turned it the other way .. the other wheel turned in the other direction!!...hmm..sort of an electronic mini car differential
     
  6. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    An electric motor works backwards as a generator, steppers do this as well as conventional motors - EPE did an article on a batteryless torch using a stepper motor the other year.
     
  7. williB

    williB New Member

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    i had a neighbor that called a flashlight a torch.
    over here , a torch is what the croud was using to find Frankenstein at night.. :shock: :wink: :wink:
     
  8. Optikon

    Optikon New Member

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    yes... HA HA... I always smile when I see "torch".. Frankenstein is precisely the image that pops into my mind! LOL
    :D
     
  9. williB

    williB New Member

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    Yeah mine too !! :lol: :lol:
     
  10. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    The English are far too civilised for such primative thoughts :lol:
     
  11. williB

    williB New Member

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    but are they good spellers :shock: :wink:
     
  12. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    Not me anyway 8)
     
  13. williB

    williB New Member

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  14. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    Why not just use the details for the PICKit 1 on MicroChips website?, it gives the circuit, source code for the 745, and source code for the VB program to run on the PC.

    Basically both the PICKit 1 and the PIC Net design use the code from the original 745 application note.
     
  15. williB

    williB New Member

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    I thought that i would show yall my robot car .
     

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  16. williB

    williB New Member

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    this board takes the signals from the PC .. later on from the Pic..
    and drives the steppers..
     

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  17. williB

    williB New Member

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    I think i should tie the FET inputs lightly to ground...lol. Just in case..
    oh a 330 uF capicitor across the power supply eliminates the spikes, and does'nt round the edges too much..
     
  18. williB

    williB New Member

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    this is my new setup.. that is the ICSP cable on the front..cool huh..
    my next step is to drive the steppers with just the pic..
     

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  19. williB

    williB New Member

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  20. williB

    williB New Member

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  21. bloody-orc

    bloody-orc New Member

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    hey what steppers did you use and how much current\voltage do they take?
    i´m thinking of mooving my own robot with steppers but when i put my stepper running on the table without any wheels or anything then it seems that the stepper is to weak :( i have a 5V\0.5A stepper and controller is uln2003a and pic
     

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