Hypertherm V9 Series Phoenix Rev.11 - Manual (Page 72)

72 Phoenix 9.76.0 Installation and Setup Manual 806410
2 – Machine Setup
Proportional Gain: Proportional Gain correlates to elastic stiffness in the control loop. Increasing the proportional gain
increases the static stiffness, but decreases response of the servo loop.
Under proportional loop control, the drive system will apply a restoring torque to the motor in proportion to
the position error of the axis.
With a Proportional Gain too high, the system will be unstable which will result in overshoots and a generally
“nervous” and shaky axis. This is also referred to as a “hot” control loop.
With a proportional gain too low, the system will respond in a loose or sloppy manner. This can be seen in
the test pattern when the outside corners become rounded and the circle segments do not all meet in the
center.
Integral Gain: Integral Gain improves the positioning accuracy of the control loop.
Integral Gain can be used to compensate for static friction or gravity. Excessive Integral Gain can result in
system instability.
For most shape cutting machines, this parameter should be set to zero (0).
Derivative Gain: Derivative Gain helps to dampen sudden changes in velocity. The higher the Derivative Gain, the
slower the response time to the control loop.
For most velocity loop drives, this parameter will be set to zero (0).
Feedforward Gain: Feedforward Gain can be used to drive the following error to zero during machine motion. In all
digital control loops there is a finite amount of error that is introduced by the velocity command.
Increasing Feedforward Gain can reduce this introduced error.
Velocity Gain: When using a current loop amplifier, the internal velocity loop in the CNC can be used to provide
dampening without an external tachometer.
Using the internal velocity loop with a current loop amplifier can result in higher static stiffness, smoother
machine motion, and less overshoot.
Servo Error Tolerance: Servo error, also called following error, is the difference between the commanded motor
position and the actual motor position. The servo error tolerance is the upper limit of the amount of following
error allowed before the CNC faults.
The amount of servo error tolerance depends on the cutting system mechanics. Setting the servo error
tolerance too low could cause the CNC to fault repeatedly. Setting it too high could cause inaccurate
motion or mechanical harm. Set the Following Error parameter in the Watch window and observe
steady-state operation of the cutting system (some following error is normal). Set the servo error tolerance to
a value slightly higher than the steady-state following error.
Encoder Counts per rev: Enter a value that is the number of encoder edges per revolution of the Contour Bevel Head
axis.
It is possible to enter fractional encoder units and the CNC will keep track of these fractions automatically.
Encoder Counts per rev are equal to the resolution of the encoder multiplied by the encoder revolutions per
rev.