- Encoder: [[file:doc/L-9517-9678-05-A_Data_sheet_VIONiC_series_en.pdf][Renishaw Vionic]] and used [[file:doc/L-9517-9862-01-C_Data_sheet_RKLC_EN.pdf][Ruler]]
To have a quasi-static excitation between -80 and 150V.
As the gain of the PD200 amplifier is 20, the DAC output voltage should be:
\[ V_{dac}(t) = 3.25 + 4.25\sin(2\pi \cdot t) \]
Verify that the voltage offset is zero!
Measure the output vertical displacement $d$ using the interferometer.
Then, plot $d$ as a function of $V_a$, and perform a linear regression.
Conclude on the obtained stroke.
** Stiffness Measurement
Add some (known) weight $\delta m g$ on the suspended mass and measure the deflection $\delta d$.
This can be tested when the piezoelectric stacks are open-circuit.
As the stiffness will be around $k \approx 10^6 N/m$, an added mass of $m \approx 100g$ will induce a static deflection of $\approx 1\mu m$ which should be large enough for a precise measurement using the interferometer.
Then the obtained stiffness is:
\begin{equation}
k = \frac{\delta m g}{\delta d}
\end{equation}
** Hysteresis measurement
Supply a quasi static sinusoidal excitation $V_a$ at different voltages.
The offset should be 65V, and the sin amplitude can range from 1V up to 85V.
For each excitation amplitude, the vertical displacement $d$ of the mass is measured.
Then, $d$ is plotted as a function of $V_a$ for all the amplitudes.
** Piezoelectric Actuator Constant
Using the measurement test-bench, it is rather easy the determine the static gain between the applied voltage $V_a$ to the induced displacement $d$.
Use a quasi static (1Hz) excitation signal $V_a$ on the piezoelectric stack and measure the vertical displacement $d$.
Perform a linear regression to obtain:
\begin{equation}
d = g_{d/V_a} \cdot V_a
\end{equation}
Using the Simscape model of the APA, it is possible to determine the static gain between the actuator force $F_a$ to the induced displacement $d$:
\begin{equation}
d = g_{d/F_a} \cdot F_a
\end{equation}
From the two gains, it is then easy to determine $g_a$:
Alternatively, we could impose an external force to add strain in the APA that should be equally present in all the 3 stacks and equal to 1/5 of the vertical strain.
This external force can be some weight added, or a piezo in parallel.
** Capacitance Measurement
Measure the capacitance of the 3 stacks individually using a precise multi-meter.
Perform a system identification from $V_a$ to the measured displacement $d$ by the interferometer and by the encoder, and to the general voltage $V_s$.
This can be performed using different excitation signals.
This can also be performed with and without the encoder fixed to the APA.
** Compare the results obtained for all 7 APA300ML
Compare all the obtained parameters for all the test APA.
