High-resolution encoder offers multi-turn absolute feedback at zero incremental cost

Kollmorgen servo motors are now available with its fourth generation SFD-M smart feedback device. Supplied at no additional cost over its earlier SFD models, this encoder delivers four times greater positioning accuracy and uses energy-harvesting technology to track absolute multi-turn positioning even when the system is powered off.

Kollmorgen has released the new SFD-M (Smart Feedback Device, Multi-Turn). It enables machine builders to accomplish high-resolution multi-turn feedback with absolute positioning information available at system startup.

Designed to work with AKDTM and AKD2G drives, this absolute multi-turn encoder can be integrated into Kollmorgen-housed servo motors at no extra charge compared to the SFD-3 single-turn absolute encoder, delivering multi-turn performance, four times greater positioning accuracy and fifty times lower EMF noise.

Comparable third-party encoders come with a premium price. With the new device, customers can achieve significant savings in machine designs that perform at the highest precision, efficiency and effectiveness levels.

The device measures the position of the rotor shaft throughout each 360º rotation without needing a reference to a home position, and it registers the total number of rotations the shaft has made in either direction.

This absolute multi-turn positioning capability is excellent when precise position tracking is needed over large rotational distances, such as in machine tool positioning, packaging machines, material handling, satellite tracking and many other applications.

Further, the device maintains absolute positioning information in real-time even when the system is powered down, eradicating the necessity for time-consuming homing sequences upon startup.

Absolute multi-turn encoders from other providers often need a battery to retain positioning information when the system is powered down or during a power failure. These external batteries necessitate replacement and can be subject to failure. Other alternatives include mechanical gear trains, which are noisy and backlash-prone and add size to the motor.

The new Kollmorgen SFD-M eradicates these issues, instead using energy-harvesting technology to reliably maintain positioning information without needing batteries or gear trains. Battery-free operation eliminates maintenance issues while supporting efforts to reduce the consumption of natural resources and minimise waste.

"Our new SFD-M encoder provides multi-turn absolute functionality with exceptional position accuracy and resolution at zero additional cost over Kollmorgen motors with single-turn encoders," said Chris Cooper, Kollmorgen's senior director of Global Product Management.

"That's a huge benefit for precision and productivity at a savings of hundreds of dollars per motor and potentially several thousand dollars in a complex, multi-axis machine. Single motor-to-drive cable technology with auto-drive setup further lowers total costs. We are very proud to offer all of these benefits to our customers as an integral part of Kollmorgen's industry-leading servo systems."