Harmonic Drive HMA Series, Manual

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1-8 Detector specifications (Absolute encoder)
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1-8 Detector specifications (Absolute encoder)
Absolute encoders installed in the HMA series are multi-turn absolute encoders. The encoder consists
of a single-turn detector for detecting the motor shaft position, and a multi-turn detector for detecting
the number of revolutions.
The encoder constantly detects the absolute position of the machine and stores it by means of the
battery backup, regardless of whether the driver or external controller power is turned ON or OFF.
Accordingly, once the origin is detected when the machine is installed, originating is not required for
subsequent power ON operations. This facilitates the recovery operation after a power failure or
breakdown.
The single-turn absolute position detector and the accumulation counter that detects the number of
revolutions are both made dual-redundant, where data is constantly checked between two identical
devices while the power is ON to ensure a highly reliable design that allows self-detection of encoder
errors should they occur.
In addition, a backup capacitor is installed in the encoder to retain absolute positions even when the
driver-encoder extension cable is disconnected for initial startup of the device, etc. (internal backup).
However, the backup capacitor has a limited life and its performance deteriorates. Therefore, it is
recommended that you replace the battery in the battery backup built in the HA-800 driver while the
driver is receiving power.
Specifications
Type
*1
Magnetic sensor/electronic battery backup type
(Single-turn optical sensor, multi-turn magnetic sensor/electronic battery backup
type)
Resolution
Single-turn
detector
2
17
: 131,072 pulses
Multi-turn
detector
2
16
: 65,536 (-32,768 to 32,767)
Maximum allowable motor
shaft rotational speed
7,000 r/min
*2
Safety/redundancy
･
Check method in which two identical single-turn detectors are compared
･
Check method in which two identical cumulative revolution counters that detect
the number of revolutions are compared
Backup time by external
battery
1 year (when power is not supplied)
Backup time by internal
battery
30 minutes (after 3 hours of charge, ambient temperature of 25
℃
, axis stopped)
(For backup while the driver and encoder are disconnected briefly)
*1: HMAC08 is equipped with an optical encoder; other models are equipped with a magnetic encoder.
*2: This is the rotational speed limit of the encoder and is different from the rotational speed that the motor can
drive.