Kollmorgen introduces new SFD-M multi-turn encoder

Robot and automation systems motion control components provider Kollmorgen recently introduced its fourth generation Smart Feedback Device, Multi-Turn (SDF-M).

The feedback sensor allows robot systems engineers to achieve high-resolution multi-turn feedback with absolute positioning information available at system startup.

Offered at no additional cost over Kollmorgen’s earlier SFD models, the company said its latest encoder offers four times greater positioning accuracy and uses energy-harvesting technology to track absolute multi-turn positioning even when the system is powered off.

“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 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.”

SFD-M now available in servo motors

Kollmorgen’s servo motors are now available with the new SFD-M. 

Designed to work with AKDTM and AKD2G drives, the SFD-M absolute multi-turn encoder can be integrated into Kollmorgen housed servo motors at no additional charge compared to the SFD-3 single-turn absolute encoder, providing up to 50 times lower EMF noise.

With the SFD-M, Kollmorgen said customers can achieve savings in machine designs that perform at the highest levels of precision, efficiency and effectiveness.

Turn tracking for packaging, material handling

The SFD-M measures the position of the rotor shaft throughout each 360 degree rotation without requiring 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 ideal when precise tracking of position is required over large rotational distances, such as in machine tool positioning, packaging machines, material handling, satellite tracking and many other applications.

Additionally, the SFD-M maintains absolute positioning information in real time even when the system is powered down, eliminating the need for time-consuming homing sequences upon startup.

Energy-harvesting technology

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

The new Kollmorgen SFD-M instead uses energy-harvesting technology to reliably maintain positioning information with no need for batteries or gear trains. Kollmorgen said battery-free operation reduces maintenance issues while also supporting efforts to reduce the consumption of natural resources and minimize waste.

Performance specifications

Resolution

• 24 bits per revolution
• 16,777,216 counts per revolution
• 0.0772 arc-sec per count

Multi-turn absolute range

• 16 bits = 65,536 motor revolutions

Accuracy

• < +/– 1 arc-min typical at 25ºC
• < +/– 3 arc-min worst case