
Motion Control
MultiFlex PCI 1000 Series User's Manual
83
Step 3
- Set the Proportional gain Slide Control Scale 0.20% (
Press P+ zoom button
)
Step 4
- Verify that the Proportional gain is set to 0.0001, Integral and Derivative gain = 0. Generally
Derivative gain and Integral gain are not required to tune a closed loop stepper.
Step 5
- From the
Servo Setup
dialog verify that
Closed Loop Mode
is enabled and that the
Encoder Scaling
has been set
Step 6
- Toggle the
Motor Off
and
Motor On
buttons to initialize the closed loop position registers
Step 7 -
Start the move with the
Move +
or
Move -
buttons
Step 8
- Observe the plot of following error during the move
Step 9
- Increase the proportional gain and repeat the move until the point of diminishing returns is
reached (the following error no longer decreases). Further increases of the proportional gain
will tend to cause the motor to emit a grinding noise or stall during a commanded move.
Step 10
- If the axis moves slowly near the end of the move and/or stops a few counts short of the
target the Minimum Velocity is probably set too low.
Step 11
- Save the closed loop stepper settings by selecting
Save All Axes Settings
from the Servo
Tuning
File
menu. This operation will copy all settings into the mcapi.ini file so that any
windows application program can load axis settings upon opening.
i
For additional information on using the Servo Tuning program please refer to:
The
Tuning the Servo
section of the
Motion Control
chapter
The Servo Tuning program on-line help
i
To disable closed loop stepper operation, issue the
MCSetModuleInputMode
function with
Mode
=
MC_IM_OPEN_LOOP
or deselect the closed loop check
box in the Servo Tuning Servo Setup dialog..
Reverse Phasing of a closed loop stepper
If the closed loop stepper is reverse phased, issuing a move command will cause the motor to 'take off' in
the wrong direction at full torque / speed. Once the position error exceeds the value entered for the
allowable following error (default = 1024) a motor error will occur and the axis will stop. To change the
phasing either:
Issuing the
MCSetServoOutputPhase ( )
function with
Phase
=
MC_PHASE_REVERSE
Selecting the
Reverse Phase
option in the Servo Tuning Servo Setup dialog
Swap the encoder phase A and B connections to the controller.
Closed loop stepper example
Axis 5 is a 51,200 micro steps per rotation stepper motor. A 2,000 count (500 line) incremental encoder is
coupled to the stepper motor shaft. The required maximum step rate for this application is 896,000 steps
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