Choosing the Right Rotary Servo Feedback Device - Part 3

Choosing the Right Rotary Servo Feedback Device - Part 3 Servo Motors Electromechanical and Drives Division North AmericaThis is the final of a three-part series that spoke to the various feedback devices that are provided as options on Parker Servo Motors. Part 1 & Part 2 provided the basic theory of operation for the devices and provided some guidance on why you might choose one versus the other, along with some helpful formulas for calculating required resolution. The following is a quick summary and recommendations on selecting the best feedback device for your motion control application.


Summary and recommendations

Incremental encoders (optical)

Choosing the Right Rotary Servo Feedback Device Servo Motor  Electromechanical and Drives Division

  • Good resolution - up to 20,000 ppr on standard Parker product

  • Good for applications where going back to home for out of application situation (power down) is not a concern

  • Low cost

Absolute encoders

Choosing the Right Rotary Servo Feedback Device Servo Motor Electromechanical Division

  • Provide absolute position upon powering up (no homing required)

  • Provide a very high resolution

    • 16 bit = 65,536 ppr

    • 20 bit = 1,048,576 ppr

  • Options for memory download to support “smart” encoder option

  • Option to allow for single cable from the motor for power and feedback


Choosing the Right Rotary Servo Feedback Device - Parker Servo Motor - Parker Electromechanical Division

  • Good resolution (12 bit)

  • Very rugged – 40g vibration and 200g shock

  • High temp suitability – up to 200 deg. C

  • Provide absolute position within a single turn

  • Accuracy not as good as incremental or absolute encoders

  •  Low cost

 Performance needs

  • Speed and position control
    • Understand your resolution requirement
    • Select your feedback device based on the environment and the aforementioned pros and cons
  • Torque Control
    • Feedback only provides position data to support the commutation of the motor. Go with resolver or incremental to save money

With the wide variety of application demands and environmental conditions, spanning both rotary and linear servo motor designs, selecting a compatible motor and feedback device can be a daunting task. We hope that this blog post helps in making the right choices for your most challenging applications.

Learn More

Watch this video to learn more about the features and benefits of the Parker K series frameless servo motor. The feedback devices referred to above can be readily used with this motor.



Jeff Nazzaro - Parker Servo Motor - Parker Electromechanical DivisionArticle contributed by Jeff Nazzaro, gearhead and motor product manager, Electromechanical & Drives Division, Parker Hannifin Corporation.





Related Content

Struggling to Select the Right Encoder Feedback? Read this. - Part 1

Choosing the Right Rotary Servo Motor Feedback Device - Part 2

Ensuring Precise Linear Movement With Position Feedback Systems

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