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Re: [diy_3d_printing_and_fabrication] Servo motors

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  • Graham Stabler
    if you do the sums to get say 0.1mm of resolution at the end effector needs much much more than 2048 ppr Graham ... if you do the sums to get say 0.1mm of
    Message 1 of 8 , Feb 27, 2013
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      if you do the sums to get say 0.1mm of resolution at the end effector needs much much more than 2048 ppr 

      Graham



      On 27 Feb 2013, at 11:32, Murilo Lana <murilo@...> wrote:

       

      Take a look at www.keling.com

      They have servos and other stuff at a vey good price.
      About the encoder I recommend the AMT CUI capacitive encoders. They cost about 25 bucks and have selectable resolution from 48 to 2048 PPR quadrature. Much simpler and cheaper than optical encoders. 

      Enviado via iPhone

      Em 27/02/2013, às 07:37, Graham <grezmos@...> escreveu:

       

      I doubt you would achieve suffiecient positioning resolution with that robot, the angle errors add up quickly, you really need extremely hi res encoders and servos, I doubt the installed encoders are up to it nor will the gearbox quality be up to it probably

      Graham

      On 27 Feb 2013, at 02:39, "prkeays" prkeays@...> wrote:

      > Scorbot training robotic manipulator

    • Murilo Torres
      It’s quadrature, so you get 8192 readings per revolution. If you drive a 5mm lead ball screw with this resolution you would get 0,0006mm precision. De:
      Message 2 of 8 , Feb 27, 2013
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        It’s quadrature, so you get 8192 readings per revolution. If you drive a 5mm lead ball screw with this resolution you would get 0,0006mm precision.

         

         

         

        De: diy_3d_printing_and_fabrication@yahoogroups.com [mailto:diy_3d_printing_and_fabrication@yahoogroups.com] Em nome de Graham Stabler
        Enviada em: quarta-feira, 27 de fevereiro de 2013 9:05
        Para: diy_3d_printing_and_fabrication@yahoogroups.com
        Assunto: Re: [diy_3d_printing_and_fabrication] Servo motors

         

         

        if you do the sums to get say 0.1mm of resolution at the end effector needs much much more than 2048 ppr 

         

        Graham


        On 27 Feb 2013, at 11:32, Murilo Lana <murilo@...> wrote:

         

        Take a look at www.keling.com

         

        They have servos and other stuff at a vey good price.

        About the encoder I recommend the AMT CUI capacitive encoders. They cost about 25 bucks and have selectable resolution from 48 to 2048 PPR quadrature. Much simpler and cheaper than optical encoders. 

        Enviado via iPhone


        Em 27/02/2013, às 07:37, Graham <grezmos@...> escreveu:

         

        I doubt you would achieve suffiecient positioning resolution with that robot, the angle errors add up quickly, you really need extremely hi res encoders and servos, I doubt the installed encoders are up to it nor will the gearbox quality be up to it probably

        Graham

        On 27 Feb 2013, at 02:39, "prkeays" prkeays@...> wrote:

        > Scorbot training robotic manipulator

      • Graham Stabler
        except he is not driving a leadscrew he want to use it on a robot Graham Sent from my iPad ... except he is not driving a leadscrew he want to use it on a
        Message 3 of 8 , Feb 27, 2013
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          except he is not driving a leadscrew he want to use it on a robot

          Graham

          Sent from my iPad

          On 27 Feb 2013, at 15:20, "Murilo Torres" <murilo@...> wrote:

           

          It’s quadrature, so you get 8192 readings per revolution. If you drive a 5mm lead ball screw with this resolution you would get 0,0006mm precision.

           

           

           

          De: diy_3d_printing_and_fabrication@yahoogroups.com [mailto:diy_3d_printing_and_fabrication@yahoogroups.com] Em nome de Graham Stabler
          Enviada em: quarta-feira, 27 de fevereiro de 2013 9:05
          Para: diy_3d_printing_and_fabrication@yahoogroups.com
          Assunto: Re: [diy_3d_printing_and_fabrication] Servo motors

           

           

          if you do the sums to get say 0.1mm of resolution at the end effector needs much much more than 2048 ppr 

           

          Graham


          On 27 Feb 2013, at 11:32, Murilo Lana <murilo@...> wrote:

           

          Take a look at www.keling.com

           

          They have servos and other stuff at a vey good price.

          About the encoder I recommend the AMT CUI capacitive encoders. They cost about 25 bucks and have selectable resolution from 48 to 2048 PPR quadrature. Much simpler and cheaper than optical encoders. 

          Enviado via iPhone


          Em 27/02/2013, às 07:37, Graham <grezmos@...> escreveu:

           

          I doubt you would achieve suffiecient positioning resolution with that robot, the angle errors add up quickly, you really need extremely hi res encoders and servos, I doubt the installed encoders are up to it nor will the gearbox quality be up to it probably

          Graham

          On 27 Feb 2013, at 02:39, "prkeays" prkeays@...> wrote:

          > Scorbot training robotic manipulator

        • Murilo Torres
          Ok... got it. Well, the angular resolution decreases when you get far from the axis. Using a planetary gear box or other precision reduction is a way to
          Message 4 of 8 , Feb 27, 2013
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            Ok... got it.

             

            Well, the angular resolution decreases when you get far from the axis. Using a planetary gear box or other precision reduction is a way to mechanically multiply the resolution, and of course, sacrificing the speed…

             

            De: diy_3d_printing_and_fabrication@yahoogroups.com [mailto:diy_3d_printing_and_fabrication@yahoogroups.com] Em nome de Graham Stabler
            Enviada em: quarta-feira, 27 de fevereiro de 2013 12:37
            Para: diy_3d_printing_and_fabrication@yahoogroups.com
            Assunto: Re: RES: [diy_3d_printing_and_fabrication] Servo motors

             

             

            except he is not driving a leadscrew he want to use it on a robot

             

            Graham

            Sent from my iPad


            On 27 Feb 2013, at 15:20, "Murilo Torres" <murilo@...> wrote:

             

            It’s quadrature, so you get 8192 readings per revolution. If you drive a 5mm lead ball screw with this resolution you would get 0,0006mm precision.

             

             

             

            De: diy_3d_printing_and_fabrication@yahoogroups.com [mailto:diy_3d_printing_and_fabrication@yahoogroups.com] Em nome de Graham Stabler
            Enviada em: quarta-feira, 27 de fevereiro de 2013 9:05
            Para: diy_3d_printing_and_fabrication@yahoogroups.com
            Assunto: Re: [diy_3d_printing_and_fabrication] Servo motors

             

             

            if you do the sums to get say 0.1mm of resolution at the end effector needs much much more than 2048 ppr 

             

            Graham



            On 27 Feb 2013, at 11:32, Murilo Lana <murilo@...> wrote:

             

            Take a look at www.keling.com

             

            They have servos and other stuff at a vey good price.

            About the encoder I recommend the AMT CUI capacitive encoders. They cost about 25 bucks and have selectable resolution from 48 to 2048 PPR quadrature. Much simpler and cheaper than optical encoders. 

            Enviado via iPhone


            Em 27/02/2013, às 07:37, Graham <grezmos@...> escreveu:

             

            I doubt you would achieve suffiecient positioning resolution with that robot, the angle errors add up quickly, you really need extremely hi res encoders and servos, I doubt the installed encoders are up to it nor will the gearbox quality be up to it probably

            Graham

            On 27 Feb 2013, at 02:39, "prkeays" prkeays@...> wrote:

            > Scorbot training robotic manipulator

          • Graham Stabler
            well the angular resolution stays the same as it is an angle but with a longer arm you get more movement for a given angular resolution so I know what you
            Message 5 of 8 , Feb 27, 2013
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              well the angular resolution stays the same as it is an angle but with a longer arm you get more movement for a given angular resolution so I know what you mean. Adding gearing is good if it has extremely low backlash, ideally you want to stick the encoder on the output and have a really good gearbox like a harmonic drive to stop servo oscillation. You can get high res encoders fairly cheaply, there are some 16bit absolute Avago (formally HP) ones that not too horrendously expensive and some of the magnetic ones have lots of bits, not sure of the accuracy though.

              It can be done but not easy just need to do the sums and check your wallet :)

              Graham



              On 27 Feb 2013, at 15:53, "Murilo Torres" <murilo@...> wrote:

               

              Ok... got it.

               

              Well, the angular resolution decreases when you get far from the axis. Using a planetary gear box or other precision reduction is a way to mechanically multiply the resolution, and of course, sacrificing the speed…

               

              De: diy_3d_printing_and_fabrication@yahoogroups.com [mailto:diy_3d_printing_and_fabrication@yahoogroups.com] Em nome de Graham Stabler
              Enviada em: quarta-feira, 27 de fevereiro de 2013 12:37
              Para: diy_3d_printing_and_fabrication@yahoogroups.com
              Assunto: Re: RES: [diy_3d_printing_and_fabrication] Servo motors

               

               

              except he is not driving a leadscrew he want to use it on a robot

               

              Graham

              Sent from my iPad


              On 27 Feb 2013, at 15:20, "Murilo Torres" <murilo@...> wrote:

               

              It’s quadrature, so you get 8192 readings per revolution. If you drive a 5mm lead ball screw with this resolution you would get 0,0006mm precision.

               

               

               

              De: diy_3d_printing_and_fabrication@yahoogroups.com [mailto:diy_3d_printing_and_fabrication@yahoogroups.com] Em nome de Graham Stabler
              Enviada em: quarta-feira, 27 de fevereiro de 2013 9:05
              Para: diy_3d_printing_and_fabrication@yahoogroups.com
              Assunto: Re: [diy_3d_printing_and_fabrication] Servo motors

               

               

              if you do the sums to get say 0.1mm of resolution at the end effector needs much much more than 2048 ppr 

               

              Graham



              On 27 Feb 2013, at 11:32, Murilo Lana <murilo@...> wrote:

               

              Take a look at www.keling.com

               

              They have servos and other stuff at a vey good price.

              About the encoder I recommend the AMT CUI capacitive encoders. They cost about 25 bucks and have selectable resolution from 48 to 2048 PPR quadrature. Much simpler and cheaper than optical encoders. 

              Enviado via iPhone


              Em 27/02/2013, às 07:37, Graham <grezmos@...> escreveu:

               

              I doubt you would achieve suffiecient positioning resolution with that robot, the angle errors add up quickly, you really need extremely hi res encoders and servos, I doubt the installed encoders are up to it nor will the gearbox quality be up to it probably

              Graham

              On 27 Feb 2013, at 02:39, "prkeays" prkeays@...> wrote:

              > Scorbot training robotic manipulator

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