Kollmorgen Debuts SFD-M Encoder for Multi-Turn Absolute Feedback

Kollmorgen has introduced the SFD-M absolute encoder to its line of smart feedback devices (SFD). This new high-resolution encoder offers accurate multi-turn feedback in Kollmorgen’s servo motor offerings and features advanced energy-harvesting technology, allowing systems to maintain their positions even when powered off.

Kollmorgen’s servo motor featuring the new SFD-M encoder designed for precise and efficient motion. Image used courtesy of Kollmorgen

SFD-M Absolute Multi-Turn Encoder

The new fourth-generation SFD-M absolute multi-turn encoder is designed to work with Kollmorgen’s AKD and AKD2G drives in a single motor housing. According to Kollmorgen, the new SFD-M provides four times more accuracy in positioning and significantly reduces EMF noise compared to Kollmorgen's earlier SFD-3 single-turn absolute encoder. Despite its enhancements, the SFD-M costs are the same as those of previous SFD models.

The new SFD-M encoder accurately tracks the rotor shaft's position in every 360º rotation, handles multiple rotations without needing a reference home position, and stores the total rotation count in either direction. By maintaining absolute positioning data in real time, the new encoder eliminates homing sequences during startups, which can be otherwise time-consuming.

The SFD-M encoder is available for use in Kollmorgen servo motors, helping systems designers and OEMs avoid premium prices often associated with multi-turn encoders.

The SFD-M encoder is designed for use with Kollmorgen AKD and AKD2G servo drives. Image used courtesy of Kollmorgen

Battery-free, High-resolution Performance

Traditional multi-turn encoders often rely on gear trains or batteries to retain data on the motor's position during power losses. The new SFD-M encoders, however, overcome this limitation by leveraging Kollmorgen’s “energy harvesting” technology. This battery-free technology maintains position data even in the event of power losses.

When it comes to performance, the SFD-M is engineered to deliver smooth motions and tight, precise control loops in demanding automation environments such as tool positioning, satellite tracking, and material handling. The encoder’s robust multi-turn memory tracks up to 65,536 full revolutions, ensuring seamless long-distance rotation. The SFD-M features a 24-bit resolution that delivers 16.7 million counts per revolution and smooth feedback down to 0.0772 arc seconds per count. The encoder also features an angular accuracy of <+/- 1 arc-minute at room temperature.

The SFD-M features single-cable technology that simplifies setup in servo systems. Image used courtesy of Kollmorgen

Smart Position Feedback

With support for a single motor-to-drive cable and auto-drive configurations, the SFD-M reduces wiring complexity and streamlines setup. As affirmed by Kollmorgen’s Senior Director of Global Product Management, Chris Cooper, the new solution not only offers better performance but also reduces the cost of labor and components, especially in large multi-axis machines.

As industries aim to enhance their servo system’s performance on a budget, the new SFD-M encoder stands as a potential choice for implementing smarter, low-cost, multi-turn servo systems.

Featured image used courtesy of Kollmorgen