Design World

  • Home
  • Technologies
    • 3D CAD
    • Electronics • electrical
    • Fastening & Joining
    • Factory automation
    • Linear Motion
    • Motion Control
    • Test & Measurement
    • Sensors
    • Fluid power
  • Learn
    • Ebooks / Tech Tips
    • Engineering Week
    • Future of Design Engineering
    • MC² Motion Control Classrooms
    • Podcasts
    • Videos
    • Webinars
  • LEAP AWARDS
  • Leadership
    • 2022 Voting
    • 2021 Winners
  • Design Guide Library
  • Resources
    • 3D Cad Models
      • PARTsolutions
      • TraceParts
    • Digital Issues
      • Design World
      • EE World
    • Women in Engineering
  • Supplier Listings

Novel Encoder Feedback for Position and Velocity Accuracy

By Editor | July 10, 2012

Share

For applications that require position or velocity feedback integrated into electromechanical actuators, the LinACE absolute linear encoder is a novel approach. The encoder has an accuracy of ±5 µm and delivers full closed-loop control.

The encoder comprises a solid steel shaft with fully integrated scale and a sliding read-head module with no internal moving parts, making the entire system resistant to shock and vibration. It is reliable over a wide temperature range, with an operating temperature range from -40°C to +85°C.

Renishaw-LinACE-encoder

Diagram of the absolute code under the shaft surface of the LinACE encoder

As with most actuators, the shaft is made from steel, to exploit its ‘soft’ magnetic characteristics. The absolute code under the shaft surface is composed of small circumferential grooves, which are filled with non-magnetic material such as hard chrome or copper, depending on the application. Finally, the surface is plated with hard chrome and polished to a fine finish.

Since the scale is passive, external magnetic fields have negligible effect and LinACE is immune to dirt contamination. Because the scale extends all round the shaft, it can even be rotated as it moves in and out without losing position. Furthermore, the scale manufacturing technique retains a hard, smooth outside surface on the shaft, so operation of the actuator is not affected by its presence. Shaft diameters range from 4 mm to 30 mm and measuring lengths are up to 750 mm.

LinACE-absolute-encoder

LinACE absolute encoder being used on an example actuator

The scale is read by a module that incorporates a custom-made ASIC with an array of Hall-effect sensors, for a reliable, compact, solid-state detection method. Signals from the ASIC are processed to provide a range of industry-standard output configurations, allowing replacement of traditional analog voltage or current transducers, classical potentiometers and LVDTs. Furthermore, absolute positions can be communicated in a range of protocols including CAN, SSI, SPI, I2C, RS422, RS485 asynchronous serial and PWM, with a range of resolutions from 100 µm to 0.5 µm.

The module includes two bronze bearings that are integrated in the stainless steel housing for smooth movement while maintaining precise alignment of the sensor over the shaft, even under hostile conditions.

Renishaw-LinACE-absolute-shaft-encoder

LinACE absolute shaft encoder.

Placing the scale directly on the actuator shaft provides several metrology benefits. First, the system has an accuracy of ±5 µm, thanks to internal compensation inside the read-head. Second, because the scale is marked directly onto the actuator shaft, it gives direct measurement of the actual position of the shaft, eliminating hysteresis and backlash while improving repeatability and stability.

LinACE can be fitted directly onto the front of an actuator, minimizing overall system size, reducing complexity and eliminating potential failure modes by removing the need for parallel measuring systems. Available in kit form, it can also be integrated into hydraulic and pneumatic actuators. The device lets designers consider new possibilities for the use of actuators in space-limited and demanding closed-loop applications.

Renishaw
www.renishaw.com


Filed Under: Design World articles, Semiconductor, Encoders • linear, Encoders • optical, Encoders (rotary) + resolvers, Encoders • absolute, Linear motion • slides, Motion control • motor controls
Tagged With: Renishaw
 

Tell Us What You Think!

Related Articles Read More >

Motion & Control Enterprises purchases RSA and Global Controls, fourth acquisition this year
49503-ACS Motion-CMxa
ACS Motion Control releases SPiiPlusCMxa EtherCAT motion controller
SDP-SI-040
SDP/SI launches brushless DC motors and motion control products series
PACMotion-servos
High-performance integrated motion control line from Emerson

DESIGN GUIDE LIBRARY

“motion

Enews Sign Up

Motion Control Classroom

Design World Digital Edition

cover

Browse the most current issue of Design World and back issues in an easy to use high quality format. Clip, share and download with the leading design engineering magazine today.

EDABoard the Forum for Electronics

Top global problem solving EE forum covering Microcontrollers, DSP, Networking, Analog and Digital Design, RF, Power Electronics, PCB Routing and much more

EDABoard: Forum for electronics

Sponsored Content

  • Global supply needs drive increased manufacturing footprint development
  • How to Increase Rotational Capacity for a Retaining Ring
  • Cordis high resolution electronic proportional pressure controls
  • WAGO’s custom designed interface wiring system making industrial applications easier
  • 10 Reasons to Specify Valve Manifolds
  • Case study: How a 3D-printed tool saved thousands of hours and dollars

Design World Podcasts

May 17, 2022
Another view on additive and the aerospace industry
See More >
Engineering Exchange

The Engineering Exchange is a global educational networking community for engineers.

Connect, share, and learn today »

Design World
  • Advertising
  • About us
  • Contact
  • Manage your Design World Subscription
  • Subscribe
  • Design World Digital Network
  • Engineering White Papers
  • LEAP AWARDS

Copyright © 2022 WTWH Media LLC. All Rights Reserved. The material on this site may not be reproduced, distributed, transmitted, cached or otherwise used, except with the prior written permission of WTWH Media
Privacy Policy | Advertising | About Us

Search Design World

  • Home
  • Technologies
    • 3D CAD
    • Electronics • electrical
    • Fastening & Joining
    • Factory automation
    • Linear Motion
    • Motion Control
    • Test & Measurement
    • Sensors
    • Fluid power
  • Learn
    • Ebooks / Tech Tips
    • Engineering Week
    • Future of Design Engineering
    • MC² Motion Control Classrooms
    • Podcasts
    • Videos
    • Webinars
  • LEAP AWARDS
  • Leadership
    • 2022 Voting
    • 2021 Winners
  • Design Guide Library
  • Resources
    • 3D Cad Models
      • PARTsolutions
      • TraceParts
    • Digital Issues
      • Design World
      • EE World
    • Women in Engineering
  • Supplier Listings