Dunkermotoren’s Quasi Absolute Encoder for Absolute Positioning

In any servo motion application, there needs to be a reference position. This is the physical position where the servo drive will read zero. With most absolute encoders, a special homing or referencing routine is executed, either zeroing the current position, moving the servo to a sensor, or moving the servo to a hard stop and zeroing the position once there is a position error. From this point, the system can then count the number of encoder pulses, which reports the position of the axis. If the system is powered off, the position is saved in memory, and provided the axis doesn’t move during the power off state, the position will be restored.

Dunkermotoren has added a new software feature for its absolute encoders. It allows the servo to lose power but not the position, even if there are movements after power is lost.

Dunkermotoren’s new Quasi Absolute Encoder (QAE) software feature enables precise battery-free positioning, even if a power failure occurs. Image used courtesy of Dunkermotoren

Quasi Absolute Encoder (QAE)

Referencing a servo eats up a lot of production time, especially if the axis is very long. Dunkermotoren’s new QAE software feature automatically saves the current position in the event of a power failure. Once power is restored, the encoder will report the saved position, and the servo can return to that position even if the servo moved while power was off.

With this feature, machinery that is moved would not have to be referenced again, or a vertical axis with mechanical brakes wouldn’t need to be referenced after a power cycle. This feature is sometimes seen on other servo systems, but the difference is that other manufacturers require a battery to save the position. Dunkermotoren can restore positioning without the need for a battery.

The QAE functionality is compatible with all of Dunkermotoren’s dPro and Dmove Co drives and has a single-turn resolution of 4096 cpr. This style of encoder can be used with self-locking applications, such as a vertical axis or any drive system with a mechanical brake.

Industrial farming uses servo motors to move heavy equipment accurately. Image used courtesy of Unsplash

Accurate Encoder Positioning

Some applications require high-accuracy positioning, and if you need to calibrate your system frequently, you might find your positioning varies slightly. Not all applications have a continuous power supply; for example, mobile drilling applications would be powered down and moved to a different site every day, which would require recalibration for most servo systems. By using an encoder and dPro or dMove Co servo from Dunkermotoren, the system wouldn’t need recalibration at every site, resulting in faster setup times and shorter work days.