Geschäftsführer: Dr. Bernt Götz • Telefon 03641/66880 • Fax 03641/668866 • www.piezojena.com
86
the LEDs still light up, check the connection between the amplifier and actuator. Additionally, a
mechanical blocking or overload of the actuator can prevent actuators from reaching their position.
If none of the described troubleshooting has worked, turn off the system and contact our support
team. Please do not 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.
10 controller adjustment
When any actuator made by
piezosystem jena
is connected to the EVDxxx amplifier, their specific
values are read from the actuator
’s ID-chip. The Digital Signal Processor (DSP) of the amplifier is
set with these values. 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 OFFSET potentiometer in. 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
Umes/OL
in the
analog i/o
menu.
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 OFFSET potentiometer button of the pertaining amplifier, then reset
the last values entered!
First of all check the function of the notch filter. This has been factory adjusted so that the main
resonant frequency is suppressed in an actuator with standard mass loading. If your application
has a different mass, the resonant frequency changes (higher mass = lower frequency). The notch
parameters are adjustable in the
choose menu
“
slewrate/filter
”
. In
filter type
one has to select
notch.
The bandwidth has to be reduced.
The sweep function of the internal function generator can be used to determine the resonant
frequency. Use
function generator
in the
choose menu
of the actuator. 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
menu,
set rectangle to 1 Hz, amplitude to about 50%, and offset to 25%.
Please set the monitoring output to
Umes/CL
in the
analog i/o
menu. 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 yellow). 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 in the
digital controller
menu. The overswing after the rise
time should be smaller than 1% of the total step.
