THORLABS K-Cube Piezo Controller User Manual page 32

Chapter 5
The output voltage is controlled by the DSP, allowing the Kinesis server to set the
output voltage. The output voltage can also be controlled by the top panel
potentiometer. In addition, one of the 3 possible external inputs (SMA input, Hub
Channel 1 or Hub Channel 2) can also be added to the signal that controls the output
voltage.
5.3.2 Description of Closed Loop Mode
Fig. 5.3 shows a simplified block diagram of the piezo controller in closed loop mode
(with the rear panel EXT IN terminal used for feedback)..
Off
Hub Channel 1
Hub Channel 2
EXT SMA
Hub
In closed loop, the role of the external inputs changes, and the selected input receives
the position signal from the external position reader. The DSP now implements a
digital PI (proportional-integral) control feedback loop. This control loop monitors the
actual position reading and adjusts the high voltage output to maintain a constant
position (set point). This set point can be varied by adjsuting the OUTPUT pot on the
front panel or the Output control on the GUI.
32
ADC
Pot
USB
position signal
Fig. 5.3 Closed Loop Schematic Diagram
Closed Loop
DSP DAC
TSG001
HA0365T Rev Dk Jan 2017
SMC
HV OUT
HV
Piezo
actuator