CNC Setup Utility Manual
P/N 70000490C - Tuning the Current, Velocity, and Position Controller
5-8 All rights reserved. Subject to change without notice.
10-December-04
• MC_2323: U Vel. Control Integral Timecons (.1ms)
• MC_2923: Spindle Vel. Control Integral Timecons (.1ms)
For example, if you are adjusting the X-axis, then you change the
MC_2022 and MC_2023 pair for the X-axis adjustment. Each axis has a
Machine Constant pair for the fine-tuning adjustment.
See “Velocity Proportional – Manual Tuning Test
” and “Velocity Integral –
Manual Tuning Test
.”
Position Controller Auto-tuning Test
The system provides an auto-tuning feature for the position controller.
To auto-tune the position controller
1. On the Software Options menu, select Motion Setup/Testing
(option 3) and press
ENTER.
2. On the MST screen, select an axis [X, Y, Z, U, or S (spindle)]. This
activates the axis.
3. Press PosTune (F8). Press the Start key to execute the command
on the active axis. (For Off-line, press Alt+S.)
The proportional gain is increased starting with a value of 10 until the
risetime is less than 50 times the sample frequency or the overshoot
is larger than 4%. The velocity setpoint, feedback, and the position
proportional gain are shown in the test window.
If velocity feedforward is active, the system also calculates friction
feedforward, MC_2x30 and MC_2231, torque offset (only for vertical
axes). Friction feedforward is used to reduce reversal spikes. If
adjustments are necessary, adjust manually. If spike is
overcompensated decrease by 10; otherwise, increase by 10. Torque
offset is only used for vertical axes. It compensates for any
gravitational force in an unbalanced vertical axis.
If velocity feedforward is activated, the gain for acceleration
feedforward, MC_2x29, is calculated. The gain is increased until the
peaks that the lag presents when accelerating and decelerating are
reduced to 10 microns.
If the lag cannot reach 10 microns or if the graph starts to degenerate,
increase MC_2x22 by 0.5 and decrease MC_2x23 by 0.005, and
repeat the test. If the test still fails, look at the plot and determine at
which point the plot starts to degenerate. Enter this value for
MC_2x29.
See “Position Proportional – Manual Tuning Test
” and “Acceleration
Feedforward – Manual Tuning Test.”
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