Skip navigation

True absolute linear and absolute rotary encoders revolutionise position feedback

March 2012

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.

RESOLUTE™ is the world’s first absolute encoder capable of 27-bit resolution at 36,000 rev/min. It has an astonishing market-leading resolution of just 1 nanometre at up to 100 m/s for both linear and rotary (angle) encoding applications.

True absolute encoding

RESOLUTE™ on RESA ring

The new system reads a unique single-track optical scale and offers further attractive benefits to machine designers by acquiring absolute position immediately upon switch-on, without the need for battery back-up. This completely eliminates the need for reference returns.

Unique combinations of ruggedness, ultra-high speed and exceptional resolution, mean that RESOLUTE™ is already attracting high levels of interest from manufacturers of high-performance lathes as well as slower-moving axes requiring the highest levels of precision and motion control integrity.

Outstanding positional stability

RESOLUTE™ absolute optical encoder readhead

RESOLUTE™ can serve this wide range of markets because it offers more than just raw speed and high resolution.

The RESOLUTE™ absolute encoder uses sophisticated new optics to read the fine pitch 30 µm scale with impressive low noise levels (jitter <10 nm RMS) for outstanding positional stability, while the enhanced detection method intrinsically provides a very low sub-divisional error (SDE) of ±40 nm. The result is better surface finish of machined parts from CNC machine tools, better scanning and velocity control, and rock-solid servo stiffness on linear motors or rotary direct-drives when holding position.


Advantages of single track, optical absolute scale

RESOLUTE™ RESA absolute scale close up

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.


Linear encoder options

RESOLUTE™ on RSLA with FASTRACK™ RTLA

The linear encoder version of RESOLUTE™ is available with a comprehensive range of scale options. RELA Invar spars offer “zero” expansion and ±1 µm accuracy on lengths up to 1 m. For high performance on long axes and significantly more robustness than glass scales, RSLA stainless steel spars have a total accuracy of ±4 µm over 5 m. Plus, for the quickest and easiest installation there's FASTRACK™ and RTLA tape scale with ±5 µm/m accuracy.

Angle encoder options

Angle encoder options are also well catered for; RESA rings are bolt-hole compatible with Renishaw's leading SiGNUM™ RESM rings and are offered in a standard range of diameters from 52 mm to 550 mm, with even larger size options available to order. Like the SiGNUM™ RESM, RESA rings feature large through-holes for easy design-in and a patented taper mount for quick, easy and precise adjustment of eccentricity, whilst minimising shaft preparation costs.


Ultimate reliability and safety

RESOLUTE™ absolute encoder linked RESA and REXA rings

Ultimate reliability is assured with RESOLUTE™'s IP64 sealed readhead with wipe-clean recovery. The precision optics give excellent immunity to dirt on the scale, which is further enhanced by extensive redundancy in the scale code. Safety is assured by a built-in separate and independent position checking algorithm. This actively checks every reading, ensuring any potential problem is flagged long before it reaches the controller.

The revolutionary readhead also incorporates a temperature sensor to measure heat build-up giving extra system protection, by signalling an alarm condition if head temperature rises above +80°C. This alarm is in addition to the signal monitoring, position-checking and speed monitoring that is carried out constantly inside the readhead.

The RESOLUTE™ absolute encoder uses purely serial communication resulting in exceptional noise immunity. It is available with a variety of protocols to enable easy connection to a wide range of industry-standard controllers and potential customers are advised to check with Renishaw for the latest list.

As with all Renishaw position encoders, RESOLUTE™ is backed by a truly responsive global sales and support network. Furthermore it satisfies the highest environmental standards, with both WEEE and RoHS compliance.

Find out more about RESOLUTE absolute optical encoder.

 

Editor downloads

Images

Data sheets