Geschäftsführer: Dr. Bernt Götz • Telefon 03641/66880 • Fax 03641/668866 • www.piezosystem.de
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continue working after your actuator has been damaged.
The values of calibration are valid only for a specified assembly configuration. Any change
in the assembly configuration can cause the modes OVL or UDL. Please provide us with
your assembly configuration in advance.
14. controller adjustment
When any actuator made by
piezosystem jena
is connected to the
d-Drive
pro
, their specific values
are read from the actuator
’s ID-chip. The Digital Signal Processor (DSP) of the device is set with
these values automatically. These parameters were investigated in the
piezosystem jena
laboratory and ensure safe function of the actuator.
There are no kp-, ki- and kd-values for actuators without a measurement system because the
closed loop mode is impossible in this configuration. Closed loop is automatically switched off.
To adapt the controller properties to your special application, please start with the default values.
First turn on the closed loop mode by pressing the OL/CL-button. Change one parameter step by
step and check the result with the oscilloscope on the “ANALOG” socket of the pertaining amplifier.
You must install the monitoring output to
Upos/OL
with the
monsrc
command.
In general, change the parameters in small steps and, depending on the actuator's reaction,
slightly increase the step width. If the system begins to oscillate, switch off the closed loop
immediately by pressing the OL/CL-button of the pertaining amplifier, then reset the last values
entered!
First check the function of the notch filter. The notch filter is switched off as our factory standard
setting. If the application has a new weight or special setups are given, the resonant frequency of
the whole system will change (bigger mass = lower resonant frequency).
The sweep function of the internal function generator can be used to determine the resonant
frequency. Please read 10.3.1 sweep generator. Set the amplitude to 5%, the offset to 0%, and the
sweep time to 1 (1 sec/decade). Set the
amplifier to open loop (“OL/CL” LED lights green). With
the MOD/MON cable (MON plug) you can connect the oscilloscope to the ANALOG socket of the
amplifier. The following adjustments on the oscilloscope are required: store function, time base =
0.5 sec/div, and input voltage = 0.1 V/div. The display shows the response of the actuator
measured by the integrated measurement system. Before the measured curve swings out, there is
a position where the amplitude is 0 Volts. This is the adjusted notch frequency. At the resonant
frequency, the measured curve goes very high. At this point you have to adjust the notch frequency
to the resonant frequency to linearize the curve. Using the notch filter might increase noise.
The correct ki-value is determined as follows:
In the function generator set rectangle to 1 Hz, amplitude to about 50%, and offset to 25%. Please
set the monitoring output to
Upos/CL
with the
monsrc
command. The following adjustments on
the oscilloscope are required: store function, time base=0.05 sec/div, and input voltage=1 V/div.
Set the amplifier to closed loop (OL/CL-LED lights red). The oscilloscope display shows the step
response of the actuator measured by the integrated measurement system. If the slew rate is too
low, please increase the ki-value. The overswing after the rise time should be smaller than 1% of
the total step.
In these adjustments, the actuator system can begin to oscillate in resonant frequency.
Please switch off the closed loop immediately by pressing OL/CL-button of the concerned
amplifier. Then reset the last values entered! Continuous use at resonance can damage the
actuator!
Now you can try to increase the slew rate
,
as long as no oscillation or large overshooting occurs.
