Delta Tau GEO BRICK LV Manuel D’Utilisation
Turbo PMAC User Manual
Basic Motor Setup
85
Proportional Gain: Ixx30
The proportional gain term Ixx30 is set according to the equation:
The proportional gain term Ixx30 is set according to the equation:
)
MHz
(
PFMCLK
*
08
Ixx
000
,
660
30
Ixx
=
For example, with PFMCLK at the default of 9.83 MHz, and Ixx08 at the default of 96, Ixx30 = 660,000 /
(96 * 9.83) = 700.
(96 * 9.83) = 700.
Derivative Gain: Ixx31
The derivative gain term Ixx31 is set to zero, because the loop behaves like a velocity-loop servo drive,
and there is no need to have the Turbo PMAC add damping.
The derivative gain term Ixx31 is set to zero, because the loop behaves like a velocity-loop servo drive,
and there is no need to have the Turbo PMAC add damping.
Velocity Feedforward Gain: Ixx32
The velocity feedforward gain term Ixx32 is set according to the equation:
The velocity feedforward gain term Ixx32 is set according to the equation:
)
kHz
(
ServoFreq
*
6660
32
Ixx
=
where ServoFreq is the frequency of the servo interrupt as established by I7m00, I7m01, and I7m02 (or
I6800, I6801, and I6802 on a Turbo PMAC2 Ultralite). For example, with ServoFreq at the default of
2.26 kHz (I7m00=6527, I7m01=0, I7m02=3), Ixx32 = 6660 * 2.26 = 15,050.
I6800, I6801, and I6802 on a Turbo PMAC2 Ultralite). For example, with ServoFreq at the default of
2.26 kHz (I7m00=6527, I7m01=0, I7m02=3), Ixx32 = 6660 * 2.26 = 15,050.
If you set Ixx30 differently from what its above formula dictates, Ixx32 should be changed from the value
its above formula dictates in inverse proportion to the change in Ixx30. For instance, if Ixx30 is half of
what is calculated above, Ixx32 should be twice what is calculated above.
its above formula dictates in inverse proportion to the change in Ixx30. For instance, if Ixx30 is half of
what is calculated above, Ixx32 should be twice what is calculated above.
Integral Gain and Mode: Ixx33, Ixx34
The integral gain term Ixx33 typically is set to zero because there are no offsets or disturbances to the
digital electronic loop. Some people will use integral gain to force zero steady-state errors, even when
other gains are not well set.
The integral gain term Ixx33 typically is set to zero because there are no offsets or disturbances to the
digital electronic loop. Some people will use integral gain to force zero steady-state errors, even when
other gains are not well set.
Integration mode Ixx34 is irrelevant if Ixx33 is set to zero. If Ixx33 is used, setting Ixx34 to 1 turns on
the integral gain only when the commanded velocity is zero; setting Ixx34 to 0 turns it on all of the time.
the integral gain only when the commanded velocity is zero; setting Ixx34 to 0 turns it on all of the time.
Acceleration Feedforward Gain: Ixx35
The acceleration feedforward gain term Ixx35 typically is set to zero, because the electronic loop has no
inertia to overcome. However, some users will want to use Ixx35 to compensate for the small time delays
created by the addition process in pulse generation that will cause small following errors when the
velocity is changing. For a given servo update time, an optimum Ixx35 value can be found that virtually
eliminates errors at all accelerations.
The acceleration feedforward gain term Ixx35 typically is set to zero, because the electronic loop has no
inertia to overcome. However, some users will want to use Ixx35 to compensate for the small time delays
created by the addition process in pulse generation that will cause small following errors when the
velocity is changing. For a given servo update time, an optimum Ixx35 value can be found that virtually
eliminates errors at all accelerations.
Notch Filter Parameters: Ixx36 – Ixx39
Notch filter parameters Ixx36 to Ixx39 are set to zero in the open-loop case, because the electronic loop
itself has no resonance, even if the mechanical system does.
Notch filter parameters Ixx36 to Ixx39 are set to zero in the open-loop case, because the electronic loop
itself has no resonance, even if the mechanical system does.
Testing the Setup
Preparing for the Test
With an open-loop system, you can test much of the initial operation of the setup without attaching
anything to the Turbo PMAC, because the loop operates entirely within Turbo PMAC. To do this, you
will have to disable your position limits by setting bit 17 of Ixx24 to 1. If no other bits of Ixx24 were set
to 1, this would mean setting Ixx24 to $20000.
anything to the Turbo PMAC, because the loop operates entirely within Turbo PMAC. To do this, you
will have to disable your position limits by setting bit 17 of Ixx24 to 1. If no other bits of Ixx24 were set
to 1, this would mean setting Ixx24 to $20000.
The initial test should be simple monitoring of motor position and velocity as commands are given to the
motor. The position-reporting window in the PMAC Executive program provides a very convenient way
to monitor this. Select the window option that displays position, velocity, and following error for the
motor you are testing. Specify the units of the reported position and velocity (counts per second for
velocity equals Hertz).
motor. The position-reporting window in the PMAC Executive program provides a very convenient way
to monitor this. Select the window option that displays position, velocity, and following error for the
motor you are testing. Specify the units of the reported position and velocity (counts per second for
velocity equals Hertz).