JVL MAC050 - High Resolution Velocity

82 JVL A/S - User Manual - Integrated Servo Motors MAC050 - 4500
2.18 High resolution velocity
2.18.1 Introduction
This feature offers the possibility to obtain 2 things:
1. The motor velocity and acceleration can be set with a 64 times higher resolution than
normally.
2. The positioning range is expanded to full 32 bits.
2.18.2 Function description
Traditionally, the JVL MAC motors have used an internal resolution 16 times higher than
the physical encoder resolution of 8000/8192 pulses per revolution.
This allows the user to select target/maximum velocity and acceleration with a 16 times
higher resolution.
However, some applications need an even higher resolution than the default resolution
for the motors
This feature offers 1024 times higher velocity resolution than the physical encoder.
This can be accomplished by setting a bit in the setup bits register.
This will have the following effects:
1. The Velocity registers get a 64 times higher resolution.
2. The Acceleration registers get a 64 times higher resolution.
3. The valid position ranges in Position and Gear modes are expanded from +/-67mil-
lion counts to +/- 2147 million counts.
4. The internal Position registers get a 64 times higher scaling.
5. The internal Position registers change from 32 bit to 64 bit.
The following paragraphs list more details, including all registers affected.
The scaling of the Actual Velocity and Actual Position registers are NOT changed and has
the same resolution regardless if the high resolution velocity is enabled or not.
To get an idea of the improvement in resolution, the following two tables show how
many RPM one count in the Target Velocity registers means for supported sample times
and encoder resolutions. Values are in RPM per count:
The formula is RPM/Count = (sample_frequency_in_Hz * 60) / (encoder_resolution *
(1024 or 16)).
Classic resolution (default):
Note: Only MAC800-1200 in some versions are available with 8000 CPR encoder. All other motors are
with 8192 CPR encoders.
Sample
time
Sample
frequency
Encoder resolution
(RPM/count)
Encoder used
8000 CPR
Encoder used
8192 CPR
1.0 ms 1000 Hz 0.468750000 0.457763671
1.3 ms 769.23 Hz 0.360576562 0.352125901
2.0 ms 500 Hz 0.23437500 0.228881835
2.6 ms 384.61 Hz 0.180288281 0.176062950