RESOLUTE™ absolute optical encoder - Performance

Renishaw is introducing RESOLUTE, a true absolute, fine pitch optical encoder system that has excellent dirt immunity, and an impressive specification that breaks new ground in position feedback.

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Renishaw is introducing RESOLUTE, a true absolute, fine pitch optical encoder system that has excellent dirt immunity, and an impressive specification that breaks new ground in position feedback.

Motion control performance

Typical sub-divisional error graph for RESOLUTE™ absolute encoderTypical noise (Jitter) graph for RESOLUTE™ absolute optical encoder

RESOLUTE's astonishing performance is the result of a sophisticated, reliable and completely unique method of operation. Think of RESOLUTE as an ultra-fast miniature digital camera, taking photos of a scale that consists of a long, non-repeating bar code.

RESOLUTE analyses these photos to determine its position down to resolutions as small as 1 nanometre (1 billionth of a metre) and with remarkable low noise (jitter to 7 nm RMS) and SDE (sub-divisional error, the error within a scale grating period) of just ±40 nm. This provides encoder feedback of superior fidelity, to ensure smoother velocity control and rock-solid positional stability.

Click on graph to enlarge

High speed absolute encoder

RESOLUTE's unique method of operation enables very high speeds to be achieved. The maximum surface reading speed is 100 m/s, which corresponds to 36,000 rev/min on a 52 mm RESA ring. Remarkably, these speeds can be achieved with resolutions as tiny as 1 nanometre (or 27 bits on a 52 mm ring).

 

 

The maximum operating speed rating for the linear encoder version is 100 m/s. The angle encoder version is ring-size dependent.

RESA diameter (mm)

Maximum operating speed (rev/min)

52

36,000

75

25,000

104

18,000

115

16,500

150

12,000

209

9000

229

8300

255

7400

300

6300

350

5400

417

4500

489

3900

550

3400

Caution: Very high speed motion axes require additional design consideration. For applications that will exceed 50% of the rated maximum operating speed of the ring, please contact Renishaw for further advice.

Fine resolution absolute encoder

The advanced optical detection method makes very fine resolutions feasible, without any compromise on speed.

Linear absolute encoder resolutions

Linear absolute encoder versions of RESOLUTE are available as standard with resolution options of 1 nm, 5 nm and 50 nm.

Rotary (angle) absolute encoder resolutions

Rotary (angle) absolute encoder versions of RESOLUTE have a variety of resolutions according to the protocol being used...

BiSS® versions are available with resolutions of 32 bits (4,294,967,296 counts per revolution), 26 bits (67,108,864 counts per revolution) and 18 bits (262,144 counts per revolution). Note that BiSS versions with 32 bit protocol are providing resolution that is below the noise floor of the encoder. Please see the RESOLUTE datasheet for more details.

FANUC versions are available with resolutions of 27 bits (134,217,728 counts per revolution) and 23 bits (8,388,608 counts per revolution). Note also that 27 bit resolution is only compatible with newer versions of Fanuc controllers. Please contact FANUC to confirm compatibility.

For resolution information for other protocols, please contact Renishaw.

High accuracy absolute encoder

Typical RESOLUTE™ RELA absolute encoder accuracy graphTypical RESOLUTE™ REXA absolute encoder accuracy graph

RESOLUTE is available with a range of high accuracy scales, in both linear and rotary format. The majority of linear users will be satisfied with the ±5 µm/m accuracy of FASTRACK™ RTLA linear tape scale and versatile RESA rings.

For even higher accuracy, Renishaw also manufacture RELA ZeroMet™ linear spars with sub-micron certified accuracy and rotary REXA rings with sub-arc second installed accuracy.

For long-length applications where metrology cannot be compromised, Renishaw recommends the use of RSLA high-accuracy stainless steel linear spars. RSLA offers a total accuracy (including slope and linearity) better than ±4 μm over 5 m – an industry first! RSLA can be coiled for simple storage and handling yet once uncoiled behaves as a spar scale.

Click on graph to enlarge

High dirt immunity

RESOLUTE™ absolute encoder scale - cleanRESOLUTE™ absolute encoder scale - particle contaminationRESOLUTE™ absolute encoder scale - grease contamination

RESOLUTE uses a state-of-the-art DSP (Digital Signal Processor) to analyse the photo to decipher all the complex aspects of code redundancy and cross-checking, focusing and motion blur, thus rejecting the effects of dirt and contamination. This analysis is so advanced that it can even calculate position in cases where parts of the code appear to the human eye to be completely obliterated by particulate contamination and even more impressively, overcome the light-scattering effects of oily or greasy smears that cause other encoders to miscount or raise alarms.

The three photos here show clean scale (top), particulate contamination (middle) and greasy contaminants (bottom). In all three cases, absolute position could be determined.

Wide set-up tolerances

Example absolute encoder with typical yaw toleranceRESOLUTE™ absolute encoder with ±0.5° yaw tolerance

RESOLUTE does not follow the conventional technique of using dual tracks side-by-side (one incremental, one absolute) which inherently suffer de-phasing problems when small amounts of angular misalignment are introduced. Instead, this new absolute encoder features a single track, optical absolute scale, combining both the absolute position and embedded phase information into one single code. This technology provides RESOLUTE with far wider set-up tolerances for quick and easy installation and superior long-term reliability, even if the motion axes settle or move over time. To further aid installation and diagnostics, there is an integral set-up LED on the readhead.

 

BiSS® is a registered trademark of iC-Haus GmbH

Data sheets

3D models (step format)

Videos