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RE: [rsa] Re: Help Needed! Chips are in, but 1 questions still

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  • Terry Kremin
    yep, you are completely correct, that is definitely it!! sorry about that. I had looked at trying to put diodes in my first homemade design, and my thought
    Message 1 of 16 , May 3 11:17 AM
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      yep, you are completely correct, that is definitely it!! sorry about that. I had looked at trying to put diodes in my first homemade design, and my thought process and logic got stuck there and I changed what I was calling them without actually changing them in my mental schematic!
       
      I feel really dumb right now! Too many things and not enough bandwidth....
       
       
       
      Thanks again for the help, and especially the rapidity of your help and suggestions - If I get any data from this rig published I will definitely give you a plug in the acknowledgements!
       

      _____________________

      Terry Kremin, Ph.D.
      Postdoctoral Fellow
      Ernest Gallo Clinic and Research Center, UCSF

      *******************
      "If the misery of the poor be caused not by the laws of nature, but by our institutions, great is our sin."      -- Charles Darwin



       


      From: sfrsa@yahoogroups.com [mailto:sfrsa@yahoogroups.com] On Behalf Of Dave Hylands
      Sent: Tuesday, May 03, 2005 9:43 AM
      To: sfrsa@yahoogroups.com
      Subject: RE: [rsa] Re: Help Needed! Chips are in, but 1 questions still

      Hi Terry,

      > Sorry for what may seem a simple (dumb)
      question,
      > but from what I know capacitors are basically a 1
      >
      way flow control valve in DC circuits, and a
      > variable frequency cut off
      depending on the
      > capacitors rating.

      I think you may be confusing diodes and capacitors. Diodes only allow current
      to flow in one direction.

      Some capacitors will only work properly if they're connected with the correct
      polarity (electrolytics and tantalums). The capacitors that you connect
      across the motor are normally monolithic or ceramic, and these types of
      capacitors work equally well with either polarity.

      A capacitor is basically like a little storage device that can hold charge.
      In the case of the motor, it absorbs the charge which is created by a current
      spike, which is noise.

      If you're familiar with modern plumbing, there's a device called a water
      hammer arrestor they often put on your water lines before going to a washing
      machine. These are basically performing the same function as a capacitor on
      the motor. When the washing machine opens the valve quickly there is a sudden
      inrush of water. The water hammer arrestor absorbs the initial shock. The
      capacitor on the motor is doing the same thing when the PWM is switching on
      and off.

      If your motor has a metal case, then adding additional capacitors from the
      metal case to each motor lead helps as well. The metal case will absorb the
      RF trasnmitted by the brushes arcing, and the capacitors will allow it to be
      dissapated.

      --
      Dave Hylands
      Vancouver, BC, Canada
      http://www.DaveHylands.com/

      -----Original Message-----
      From: sfrsa@yahoogroups.com [mailto:sfrsa@yahoogroups.com] On Behalf Of Terry
      Kremin
      Sent: Tuesday, May 03, 2005 10:25 AM
      To: sfrsa@yahoogroups.com
      Subject: RE: [rsa] Re: Help Needed! Chips are in, but 1 questions still


      Thank you again! Just got the chips in and am going to play with it today.

      Just one thing I am not clear on -
      putting a cap _across_ the motor leads.
      I understand from one current direction it will help ground out noise
      (reverse EMF?) or cut out AC frequencies, but as I am going to be using this
      motor in both directions and polarities, isn't that going to just create a
      parallel loop with the motor in one of the directions/polarities and cause
      problems?

      and from both the leads to ground will do the same(creat a closed circuit in
      one direction), correct? So the motor would just be a resistive loop attached
      in parallel to a close circuit?






      _____________________
      Terry Kremin, Ph.D.
      Postdoctoral Fellow
      Ernest Gallo Clinic and Research Center, UCSF
      *******************
      "If the misery of the poor be caused not by the laws of nature, but by our
      institutions, great is our sin."      -- Charles Darwin




      SF robot meetings are at 7PM on the first Wednesday of the month at SFSU's Science bldg - 1600 Holloway, room SCI 256.

      http://www.robotics-society.org/images/sfsu_map.gif


    • D K
      Hey Everybody, I m new to robotics and I figured I d jump right in and help out a group that needs help with updating their robot. Right now, they control
      Message 2 of 16 , Jun 20, 2005
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        Hey Everybody,

        I'm new to robotics and I figured I'd jump right in and help out
        a group that needs help with updating their robot.

        Right now, they control their robot's arms with R/C controllers,
        but they would like to have it automated/autonymous.

        So I want to use the BS2 to control the Vantec ESC RDFR.
        Are there any website/info that show example on how to
        program/wire the BS2 to send the proper PWM outs to
        the Vantec?

        Does anyone have any suggestions for a good shaft encoder to
        obtain positioining data?

        Cheers,
        DK
      • frederick chang
        Hello DK, I recommend the BASIC book written by Edwards. He goes over many examples with sample code for the basic stamp. Also, www.parallax.com
        Message 3 of 16 , Jun 20, 2005
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          Hello DK,

           

          I recommend the BASIC book written by Edwards.  

           

          He goes over many examples with sample code for the basic stamp.

           

          Also, www.parallax.com has a forum in which you can post questions regarding the use of BS2, but if you purchase that book, you’ll probably not need to use the forums.

           

          Cheers,

           


          From: sfrsa@yahoogroups.com [mailto: sfrsa@yahoogroups.com ] On Behalf Of D K
          Sent: Monday, June 20, 2005 8:48 PM
          To: sfrsa@yahoogroups.com
          Subject: [rsa] BS2, Vantec RDFR21, DC Motor ?

           

          Hey Everybody,

          I'm new to robotics and I figured I'd jump right in and help out
          a group that needs help with updating their robot.

          Right now, they control their robot's arms with R/C controllers,
          but they would like to have it automated/autonymous.

          So I want to use the BS2 to control the Vantec ESC RDFR.
          Are there any website/ info that show example on how to
          program/wire the BS2 to send the proper PWM outs to
          the Vantec?

          Does anyone have any suggestions for a good shaft encoder to
          obtain positioining data?

          Cheers,
          DK




          SF robot meetings are at 7PM on the first Wednesday of the month at SFSU's Science bldg - 1600 Holloway, room SCI 256.

          http://www.robotics-society.org/images/sfsu_map.gif



        • Camp Peavy
          On Rusty I m driving two RC car ESC s (Novak XRS s) with a BS2 and Mini Serial Servo Controller (MSSC) . ESC s take
          Message 4 of 16 , Jun 20, 2005
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            On "Rusty" I'm driving two RC car ESC's (Novak XRS's) with a BS2 and Mini Serial Servo Controller (MSSC) <http://www.camppeavy.com/rusty.jpg>.

             

            ESC's take commands just like servos. Have you used the Stamp to move a plain servo yet? If it works with a plain servo it should work with the ESC. ESC's just like servos are looking for pulses between 1 and 2 milliseconds (ms); 1-ms for one direction, 2-ms for the other and ~1.5-ms to stop. If you drive it directly from the BS2 you'll use the "pulsout" command. Pulsout 500 for one direction and 1000 for the other. The BS2's pulsout command runs at 2 micro-second (1/1,000,000/sec) units so 500 x 2 micro-seconds = 1 millisecond (1/1,000/sec) and 1000 x 2 micro-seconds = 2 milliseconds. The "stop" value should be 750 but it usually ranges between 730 and 770.

             

            Once you get it going you might want to seriously consider off-loading the pulsing to a peripheral board like the MSSC otherwise your Stamp might be too busy to do anything else. With the MSSC your Stamp simply gives it a value between 0 and 254 and goes back to more important things. The peripheral board does the pulsing.

             

            One of the tricks with the Novak XRS is you had to put it in the "stop" position before changing directions. They call this “Smart Braking II”. I implemented it through a “gosub” routine.

             

            Good luck and keep us posted.

             

            Camp

             

          • D K
            Thanks Camp and Fredrick. I have run through the Stamp in Class tutorial with the BS2 to move a Servo. I just wasn t sure if that was the same approach.
            Message 5 of 16 , Jun 21, 2005
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              Thanks Camp and Fredrick.

              I have run through the Stamp in Class tutorial with the BS2 to move a Servo.
              I just wasn't sure if that was the same approach. Thanks for the info.
              I'll try it out and let you guys know how it goes.

              If anyone with robotics experience is interested in playing with and help
              modifiying our
              robot from R/C controlled to BS2 controlled please let me know and I will
              give you more details. We are located in San Francisco.

              At this time we are only looking for an experienced Robotics Volunteer.
              I'm already the inexpereinced volunteer. :)


              Cheers,
              Dennis K.
            • Camp Peavy
              ... Does this robot have a particular function or is it free-range ? Camp
              Message 6 of 16 , Jun 21, 2005
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                > If anyone with robotics experience is interested in playing with and help modifiying our robot from R/C controlled to BS2 controlled please let me know and I will give you more details. We are located in San Francisco .

                 

                Does this robot have a particular function or is it "free-range"?

                 

                Camp

              • Dong Yun Jiang
                Hi,Camp and Peavy, I want to get more details about your robot. But I don t know enough about it. Pls send to me the information as detailed as possible. ...
                Message 7 of 16 , Jun 21, 2005
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                  Hi,Camp and Peavy, I want to get more details about your robot. But I don't know enough about it. Pls send to me the information as detailed as possible.
                   
                   
                  ----- Original Message -----
                  Sent: Wednesday, June 22, 2005 1:21 AM
                  Subject: Re: [rsa] BS2, Vantec RDFR21, DC Motor ?

                  > If anyone with robotics experience is interested in playing with and help modifiying our robot from R/C controlled to BS2 controlled please let me know and I will give you more details. We are located in San Francisco .

                   

                  Does this robot have a particular function or is it "free-range"?

                   

                  Camp



                  SF robot meetings are at 7PM on the first Wednesday of the month at SFSU's Science bldg - 1600 Holloway, room SCI 256.

                  http://www.robotics-society.org/images/sfsu_map.gif


                • zaman motamedi
                  Try www.humball.com They ve a good integrated, software upgradeable controller. Z.M ... From: sfrsa@yahoogroups.com [mailto:sfrsa@yahoogroups.com] On Behalf Of
                  Message 8 of 16 , Jun 21, 2005
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                    Message
                            Try www.humball.com
                            They've a good integrated, software upgradeable controller.
                            Z.M
                    -----Original Message-----
                    From: sfrsa@yahoogroups.com [mailto:sfrsa@yahoogroups.com] On Behalf Of D K
                    Sent: Monday, June 20, 2005 8:48 PM
                    To: sfrsa@yahoogroups.com
                    Subject: [rsa] BS2, Vantec RDFR21, DC Motor ?

                    Hey Everybody,

                    I'm new to robotics and I figured I'd jump right in and help out
                    a group that needs help with updating their robot.

                    Right now, they control their robot's arms with R/C controllers,
                    but they would like to have it automated/autonymous.

                    So I want to use the BS2 to control the Vantec ESC RDFR.
                    Are there any website/info that show example on how to
                    program/wire the BS2 to send the proper PWM outs to
                    the Vantec?

                    Does anyone have any suggestions for a good shaft encoder to
                    obtain positioining data?

                    Cheers,
                    DK




                    SF robot meetings are at 7PM on the first Wednesday of the month at SFSU's Science bldg - 1600 Holloway, room SCI 256.

                    http://www.robotics-society.org/images/sfsu_map.gif


                  • Jon Nebenfuhr
                    Yummm... Free Range Robots... They re real good with mustard and onions. ... robot from R/C controlled to BS2 controlled please let me know and I will
                    Message 9 of 16 , Jun 22, 2005
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                      Yummm... Free Range Robots... They're real good with mustard and onions. <drool>

                      --- In sfrsa@yahoogroups.com, Camp Peavy <cpeavy2@y...> wrote:
                      >
                      > > If anyone with robotics experience is interested in playing with and help modifiying our
                      robot from R/C controlled to BS2 controlled please let me know and I will give you more
                      details. We are located in San Francisco.
                      >
                      >
                      >
                      > Does this robot have a particular function or is it "free-range"?
                      >
                      >
                      >
                      > Camp
                    • Camp Peavy
                      ... ... more like motors and Ohmions . ;-) - cp
                      Message 10 of 16 , Jun 22, 2005
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                        > Yummm... Free Range Robots... They're real good with mustard and onions. <drool>
                        ... more like motors and Ohmions <sorry!>. ;-) - cp
                         
                      • D K
                        So if a ESC takes commands like a servo, does the ESC also control a DC motor like a servo? More specifically will it control the DC motor output to a given
                        Message 11 of 16 , Jun 27, 2005
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                          So if a ESC takes commands like a servo, does the ESC also control a DC
                          motor like a servo?
                          More specifically will it control the DC motor output to a given position
                          based on the PWM,
                          just as a servo would be commmanded to a given position based on the PWM?

                          Or would it need feedback from an encoder to determine position?

                          How do i control the speed of the motors using the ESC if i am only sending
                          Stop (1.5ms), CCW (1 ms) and CW (2ms) PWM commands?

                          Thanks everyone for helping me with my newbie questions.

                          DK

                          ----Original Message Follows----
                          From: Camp Peavy <cpeavy2@...>
                          Reply-To: sfrsa@yahoogroups.com
                          To: sfrsa@yahoogroups.com
                          Subject: Re: [rsa] BS2, Vantec RDFR21, DC Motor ?
                          Date: Mon, 20 Jun 2005 23:27:14 -0700 (PDT)


                          On "Rusty" I'm driving two RC car ESC's (Novak XRS's) with a BS2 and Mini
                          Serial Servo Controller (MSSC) <http://www.camppeavy.com/rusty.jpg>.



                          ESC's take commands just like servos. Have you used the Stamp to move a
                          plain servo yet? If it works with a plain servo it should work with the ESC.
                          ESC's just like servos are looking for pulses between 1 and 2 milliseconds
                          (ms); 1-ms for one direction, 2-ms for the other and ~1.5-ms to stop. If you
                          drive it directly from the BS2 you'll use the "pulsout" command. Pulsout 500
                          for one direction and 1000 for the other. The BS2's pulsout command runs at
                          2 micro-second (1/1,000,000/sec) units so 500 x 2 micro-seconds = 1
                          millisecond (1/1,000/sec) and 1000 x 2 micro-seconds = 2 milliseconds. The
                          "stop" value should be 750 but it usually ranges between 730 and 770.



                          Once you get it going you might want to seriously consider off-loading the
                          pulsing to a peripheral board like the MSSC otherwise your Stamp might be
                          too busy to do anything else. With the MSSC your Stamp simply gives it a
                          value between 0 and 254 and goes back to more important things. The
                          peripheral board does the pulsing.



                          One of the tricks with the Novak XRS is you had to put it in the "stop"
                          position before changing directions. They call this �Smart Braking II�. I
                          implemented it through a �gosub� routine.



                          Good luck and keep us posted.



                          Camp
                        • Camp Peavy
                          ... The ESC will not hold position like a servo you probably want a stepper motor. I ve got this one http://www.parallax.com/detail.asp?product_id=27964 but
                          Message 12 of 16 , Jun 27, 2005
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                            > So if a ESC takes commands like a servo, does the ESC also control a DC motor like a servo?

                             

                            The ESC will not hold position like a servo you probably want a stepper motor. I've got this one http://www.parallax.com/detail.asp?product_id=27964 but haven't done anything with it yet. I'll give it a go and give you some feedback <pun intended>.

                             

                            Camp

                             

                          • William Hubbard
                            ... The Electronic Speed Controller is just that - a motor SPEED controller. You can vary the direction and speed of a motor by varying the pulse width of the
                            Message 13 of 16 , Jun 27, 2005
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                              Quoting D K <dktkd@...>:

                              > So if a ESC takes commands like a servo, does the ESC also control a DC
                              > motor like a servo?
                              > More specifically will it control the DC motor output to a given position
                              > based on the PWM,
                              > just as a servo would be commmanded to a given position based on the PWM?
                              >
                              > Or would it need feedback from an encoder to determine position?
                              >
                              > How do i control the speed of the motors using the ESC if i am only sending
                              > Stop (1.5ms), CCW (1 ms) and CW (2ms) PWM commands?
                              >
                              > Thanks everyone for helping me with my newbie questions.

                              The Electronic Speed Controller is just that - a motor SPEED controller. You
                              can vary the direction and speed of a motor by varying the pulse width of the
                              input (i.e. servo) signal. Therefore, 1ms would be full-speed in one
                              direction, and 2ms would be full-speed in the other direction. Anything in
                              between will translate to a lower speed, typically with 1.5ms being "off".

                              By the way, servos that have been modified for free rotation (i.e. to be used
                              to drive wheels) behave similarly, but don't require the added expense of an
                              ESC. But it's slower, since servos are geared down a lot. But if you're
                              looking to simply rotate something to a known position, I think a servo is the
                              simplest (and cheapest) way to go.

                              If you want to note wheel rotation on a free-wheeling motor or servo, you
                              would have to use some kind of encoder to determine rotational position. And
                              I'm sure there must be a discussion board somewhere devoted just to that
                              topic. ;)

                              Bill H.
                            • D K
                              Thanks Camp and Bill. I didn t think it would be that easy but I figure I ask. If you were interested, the group that I am helping out is called Omnicircus.
                              Message 14 of 16 , Jun 27, 2005
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                                Thanks Camp and Bill.

                                I didn't think it would be that easy but I figure I ask.

                                If you were interested, the group that I am helping out
                                is called Omnicircus. Just do a search and you'll find them online.

                                They already have robots built, but they need to be upgraded.

                                Thanks again.
                                DK



                                ----Original Message Follows----
                                From: Camp Peavy <cpeavy2@...>
                                Reply-To: sfrsa@yahoogroups.com
                                To: sfrsa@yahoogroups.com
                                Subject: Re: [rsa] BS2, Vantec RDFR21, DC Motor ?
                                Date: Mon, 27 Jun 2005 13:16:21 -0700 (PDT)


                                > So if a ESC takes commands like a servo, does the ESC also control a DC
                                motor like a servo?



                                The ESC will not hold position like a servo you probably want a stepper
                                motor. I've got this one http://www.parallax.com/detail.asp?product_id=27964
                                but haven't done anything with it yet. I'll give it a go and give you some
                                feedback <pun intended>.



                                Camp
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