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Choice of motor - application query

simonturner83
Hi

I am currently working on a design concept for a motion system - I would be very grateful for any advice that could be given on a suitable type of motor for the application (e.g. servo, stepper, DC motor etc.).
 The related requirements for the motion system are as follows:
  1. Rotate a cylindrical object placed on its side on friction rollers to allow inspection, where rotation occurs around the axial axis as per test tube rollers or pipe weld rollers.
    1. Details of the cylindrical object:
      1. It is unattached to the rollers, i.e. placed on for rotation / inspection then removed.

    2. Can weigh up to 20kg.



  • The cylindrical object is required to rotate at a very slow speed, typically 1rpm and lower, where the upper limit is likely to be in the region of 15rpm. The friction rollers on the motion system will be in the region of 1/10 to 1/20 of the circumference of the cylindrical object.

  • The rotation of the cylindrical object is required to be significantly consistent, i.e. smooth rotation with minimal stepping / juddering.

  • The motion  profile is likely to just be one full rotation of the cylindrical object at a fixed speed, but there may be a requirement to perform the rotation in increments with pauses in between (i.e. one full rotation split into 6x moves). The duty will be low, i.e. 5-10 such operations per day.

  • Allow some basic position/speed control, where closed-loop is preferable.

Many thanks.



Parents
  • 0
    The load weighs 20kg people. He is after an electrical solution. Not a problem for steppers, take my CNC lathe which has them and you wouldn't want to try to stop them! If you want a closed loop for steppers this is not a problem and not difficult to implement, but you will need a high-resolution position sensor ie. a shaft encoder. Stepper motors are a very good solution for accurate positioning and are much less complex than full servo implementations, and do not have many of the snags such as needing full data on the load inertia, stability calculations, zero drift, integral or differential control etc. They are more expensive for higher power and large quantities, but I already said that above. 3,4&5 above become fairly trivial, which is not true of a conventional full servo. The trick which you need to know is called micro-stepping. Digital is generally better and easier!
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  • 0
    The load weighs 20kg people. He is after an electrical solution. Not a problem for steppers, take my CNC lathe which has them and you wouldn't want to try to stop them! If you want a closed loop for steppers this is not a problem and not difficult to implement, but you will need a high-resolution position sensor ie. a shaft encoder. Stepper motors are a very good solution for accurate positioning and are much less complex than full servo implementations, and do not have many of the snags such as needing full data on the load inertia, stability calculations, zero drift, integral or differential control etc. They are more expensive for higher power and large quantities, but I already said that above. 3,4&5 above become fairly trivial, which is not true of a conventional full servo. The trick which you need to know is called micro-stepping. Digital is generally better and easier!
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