Kollmorgen introduced the new SFD-M (Smart Feedback Device, Multi-Turn). It allows machine builders to achieve high-resolution multi-turn feedback with absolute positioning information available at system startup. 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 multi-turn performance, four times greater positioning accuracy and fifty times lower EMF noise. With the SFD-M, customers can achieve substantial savings in machine designs that perform at the highest levels of precision, efficiency and effectiveness.
Precise and productive motion
The SFD-M measures the position of the rotor shaft throughout each 360º 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 for battery-free operation absolute multi-turn encoders from other providers 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 eliminates these issues, instead using energy-harvesting technology to reliably maintain positioning information with no need for batteries or gear trains. Battery-free operation eliminates maintenance issues while also supporting efforts to reduce the consumption of natural resources and minimize waste.
Exceptional performance
The SFD-M is highly accurate, offering a 24 bit resolution, that is 16,777,216 counts per revolution or 0.0772 arc-sec per count. The multi-turn absolute range is 16 bits, representing 65,536 motor revolutions and the typical accuracy is < +/– 1 arc-min typical at 25ºC, or < +/– 3 arc-min worst case. The new encoders offer 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
