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HA0373T Rev Ck May 2017
Chapter 6
6.2.2
Control Settings Tab
Fig. 6.2 Position aligner Control Settings panel
Feedback Loop Settings
- When operating in Closed Loop mode, the proportional,
integral and differential (PID) constants can be used to fine tune the behaviour of the
feedback loop to cha nges in the output voltage or p osition. While closed loop
operation allows more precise control of the beam position, feedback loops need to
be adjusted to suit the different types of sensor that can be connected to the system.
The default values have been optimised to work with the senso r, in the op to-
mechanical set up shown in Fig. 5.2.
Proportional
- This parameter makes a change to the output which is proportional
to the current error value. A high proportional gain results in a large change in the
output for a given error. If set too high, the system can become unstable.
It accepts values in the range 0 to 1
Integral
- This parameter accelerates the process towards the demanded set point
value, ensuring that the positional error is eventually reduced to zero. If set too
high, the output can overshoot the demand value.
It accepts values in the range 0 to 1.
Derivative
- This parameter damps the rate of change of the output, thereby
decreasing the overshoot which may be caused by the integral term. However, the
differential term also slows down system response. If set too high, it could lead to
instability due to signal noise amplification.
It accepts values in the range 0 to 1.
For more details on setting the PID parameters, see Appendix B .
