diff --git a/test-bench-apa.bib b/test-bench-apa.bib index e75acde..a727c74 100644 --- a/test-bench-apa.bib +++ b/test-bench-apa.bib @@ -11,6 +11,8 @@ } + + @book{fleming14_desig_model_contr_nanop_system, author = {Andrew J. Fleming and Kam K. Leang}, title = {Design, Modeling and Control of Nanopositioning Systems}, diff --git a/test-bench-apa.org b/test-bench-apa.org index 8bc275c..9347b71 100644 --- a/test-bench-apa.org +++ b/test-bench-apa.org @@ -109,12 +109,15 @@ CLOSED: [2024-04-02 Tue 10:17] SCHEDULED: <2024-04-02 Tue> ** DONE [#C] Add sitffness of APA shell from FEM :@philipp: CLOSED: [2024-04-02 Tue 10:01] -** TODO [#C] Check things about resistor in parallel with the force sensor +** DONE [#C] Check things about resistor in parallel with the force sensor +CLOSED: [2024-04-04 Thu 10:42] Verify that everything interesting to say about that is either done before in the thesis or in this report. -** TODO [#B] A lieu d'identifier le plant et de tracer sur le root locus, tracer le plant dampé depuis le modèle et comparer a la mesure +** CANC [#B] A lieu d'identifier le plant et de tracer sur le root locus, tracer le plant dampé depuis le modèle et comparer a la mesure +CLOSED: [2024-04-04 Thu 10:42] +- State "CANC" from "TODO" [2024-04-04 Thu 10:42] * Introduction :ignore: In this chapter, the goal is to make sure that the received APA300ML (shown in Figure ref:fig:test_apa_received) are complying with the requirements and that dynamical models of the actuator are well representing its dynamics. @@ -1861,16 +1864,25 @@ exportFig('figs/test_apa_super_element_comp_frf_force.pdf', 'width', 'half', 'he * Conclusion <> -The main characteristics of the APA300ML such as hysteresis and axial stiffness have been measured and were found to comply with the specifications. +In this study, the received amplified piezoelectric actuators "APA300ML" have been characterized to make sure they are fulfilling all the requirements determined during the detailed design phase. -The dynamics of the received APA were measured and found to all be identical (Figure ref:fig:test_apa_frf_dynamics). -Even tough a non-minimum zero was observed on the transfer function from $u$ to $V_s$ (Figure ref:fig:test_apa_non_minimum_phase), it was not found to be problematic as large amount of damping could be added using the integral force feedback strategy (Figure ref:fig:test_apa_iff). +Geometrical features such as the flatness of its interfaces, electrical capacitance and achievable strokes were measured in Section ref:sec:test_apa_basic_meas. +These simple measurements allowed for early detection of a manufacturing defect in one of the APA300ML. +Then in Section ref:sec:test_apa_dynamics, using a dedicated test bench, the dynamics of all the APA300ML were measured and were found to all match very well (Figure ref:fig:test_apa_frf_dynamics). +This consistency indicates good manufacturing tolerances, facilitating the modeling and control of the nano-hexapod. +Although a non-minimum zero was identified in the transfer function from $u$ to $V_s$ (Figure ref:fig:test_apa_non_minimum_phase), it was found not to be problematic as large amount of damping could be added using the integral force feedback strategy (Figure ref:fig:test_apa_iff). +Then, two different models were used to represent the APA300ML dynamics. +In Section ref:sec:test_apa_model_2dof, a simple two degrees of freedom mass-spring-damper model was presented and tuned based on the measured dynamics. +After following a tuning procedure (see Section ref:ssec:test_apa_2dof_model_tuning), the model dynamics was shown to match very well with the experiment. +However, it is important to note that this model only represents the axial dynamics of the actuators, assuming infinite stiffness in other directions. -- Compare 2DoF and FEM models (usefulness of the two) -- Good match between all the APA: will simplify the modeling and control of the nano-hexapod -- No advantage of the FEM model here (as only uniaxial behavior is checked), but may be useful later +In Section ref:sec:test_apa_model_flexible, a /super element/ extracted from a finite element model was used to model the APA300ML. +This time, the /super element/ represents the dynamics of the APA300ML in all directions. +However, only the axial dynamics could be compared with the experimental results yielding a good match. +The benefit of employing this model over the two degrees of freedom model is not immediately apparent due to its increased complexity and the larger number of model states involved. +Nonetheless, the /super element/ model's value will become clear in subsequent sections, when its capacity to accurately model the APA300ML's flexibility across various directions will be important. * Bibliography :ignore: #+latex: \printbibliography[heading=bibintoc,title={Bibliography}] @@ -2022,8 +2034,6 @@ if args.Ga == 0 switch args.type case '2dof' actuator.Ga = -2.5796; - case 'flexible frame' - actuator.Ga = 1; % TODO case 'flexible' actuator.Ga = 23.2; end @@ -2037,8 +2047,6 @@ if args.Gs == 0 switch args.type case '2dof' actuator.Gs = 466664; - case 'flexible frame' - actuator.Gs = 1; % TODO case 'flexible' actuator.Gs = -4898341; end diff --git a/test-bench-apa.pdf b/test-bench-apa.pdf index 53f0327..8615729 100644 Binary files a/test-bench-apa.pdf and b/test-bench-apa.pdf differ diff --git a/test-bench-apa.tex b/test-bench-apa.tex index 62d29dd..4a701ff 100644 --- a/test-bench-apa.tex +++ b/test-bench-apa.tex @@ -1,4 +1,4 @@ -% Created 2024-04-03 Wed 18:15 +% Created 2024-04-04 Thu 11:14 % Intended LaTeX compiler: pdflatex \documentclass[a4paper, 10pt, DIV=12, parskip=full, bibliography=totoc]{scrreprt} @@ -59,7 +59,7 @@ Section \ref{sec:test_apa_model_flexible} & \texttt{test\_apa\_4\_model\_flexibl \end{table} \chapter{First Basic Measurements} -\label{sec:org399d3a7} +\label{sec:org228596b} \label{sec:test_apa_basic_meas} Before measuring the dynamical characteristics of the APA300ML, first simple measurements are performed. @@ -68,7 +68,7 @@ Then, the capacitance of the piezoelectric stacks is measured in Section \ref{ss The achievable stroke of the APA300ML is measured using a displacement probe in Section \ref{ssec:test_apa_stroke_measurements}. Finally, in Section \ref{ssec:test_apa_spurious_resonances}, the flexible modes of the APA are measured and compared with a finite element model. \section{Geometrical Measurements} -\label{sec:org9db80da} +\label{sec:org726c24d} \label{ssec:test_apa_geometrical_measurements} To measure the flatness of the two mechanical interfaces of the APA300ML, a small measurement bench is installed on top of a metrology granite with excellent flatness. @@ -103,7 +103,7 @@ APA 7 & 18.7\\ \end{center} \end{minipage} \section{Electrical Measurements} -\label{sec:orgbec5e3a} +\label{sec:orgd08d506} \label{ssec:test_apa_electrical_measurements} From the documentation of the APA300ML, the total capacitance of the three stacks should be between \(18\,\mu F\) and \(26\,\mu F\) with a nominal capacitance of \(20\,\mu F\). @@ -144,7 +144,7 @@ APA 7 & 4.85 & 9.85\\ \end{center} \end{minipage} \section{Stroke and Hysteresis Measurement} -\label{sec:org7997ce8} +\label{sec:org1a772f2} \label{ssec:test_apa_stroke_measurements} In order to verify that the stroke of the APA300ML is as specified in the datasheet, one side of the APA is fixed to the granite, and a displacement probe\footnote{Millimar 1318 probe, specified linearity better than \(1\,\mu m\)} is located on the other side as shown in Figure \ref{fig:test_apa_stroke_bench}. @@ -184,7 +184,7 @@ From now on, only the six APA that behave as expected will be used. \caption{\label{fig:test_apa_stroke}Generated voltage across the two piezoelectric stack actuators to estimate the stroke of the APA300ML (\subref{fig:test_apa_stroke_voltage}). Measured displacement as a function of the applied voltage (\subref{fig:test_apa_stroke_hysteresis})} \end{figure} \section{Flexible Mode Measurement} -\label{sec:orga2217ed} +\label{sec:orgf072115} \label{ssec:test_apa_spurious_resonances} In this section, the flexible modes of the APA300ML are investigated both experimentally and using a Finite Element Model. @@ -245,7 +245,7 @@ Another explanation is the shape difference between the manufactured APA300ML an \caption{\label{fig:test_apa_meas_freq_compare}Obtained frequency response functions for the 2 tests with the instrumented hammer and the laser vibrometer. The Y-bending mode is measured at \(280\,\text{Hz}\) and the X-bending mode at \(412\,\text{Hz}\)} \end{figure} \chapter{Dynamical measurements} -\label{sec:orgdf7ee61} +\label{sec:org2e49535} \label{sec:test_apa_dynamics} After the basic measurements on the APA were performed in Section \ref{sec:test_apa_basic_meas}, a new test bench is used to better characterize the dynamics of the APA300ML. This test bench, depicted in Figure \ref{fig:test_bench_apa}, comprises the APA300ML fixed at one end to a stationary granite block, and at the other end to a 5kg granite block that is vertically guided by an air bearing. @@ -281,7 +281,7 @@ Finally, the Integral Force Feedback is implemented, and the amount of damping a \caption{\label{fig:test_apa_schematic}Schematic of the Test Bench used to measured the dynamics of the APA300ML. \(u\) is the output DAC voltage, \(V_a\) the output amplifier voltage (i.e. voltage applied across the actuator stacks), \(d_e\) the measured displacement by the encoder and \(V_s\) the measured voltage across the sensor stack.} \end{figure} \section{Hysteresis} -\label{sec:org7aacb8e} +\label{sec:org63e3610} \label{ssec:test_apa_hysteresis} As the payload is vertically guided without friction, the hysteresis of the APA can be estimated from the motion of the payload. @@ -295,7 +295,7 @@ This is the typical behavior expected from a PZT stack actuator where the hyster \caption{\label{fig:test_apa_meas_hysteresis}Obtained hysteresis curves (displacement as a function of applied voltage) for multiple excitation amplitudes} \end{figure} \section{Axial stiffness} -\label{sec:org5cd81d2} +\label{sec:org68f94d3} \label{ssec:test_apa_stiffness} In order to estimate the stiffness of the APA, a weight with known mass \(m_a = 6.4\,\text{kg}\) is added on top of the suspended granite and the deflection \(d_e\) is measured using the encoder. @@ -357,7 +357,7 @@ To estimate this effect for the APA300ML, its stiffness is estimated using the ` It is found that the open-circuit stiffness is estimated at \(k_{\text{oc}} \approx 2.3\,N/\mu m\) while the the closed-circuit stiffness \(k_{\text{sc}} \approx 1.7\,N/\mu m\). \section{Dynamics} -\label{sec:org9be9924} +\label{sec:org7856f12} \label{ssec:test_apa_meas_dynamics} In this section, the dynamics from the excitation voltage \(u\) to the encoder measured displacement \(d_e\) and to the force sensor voltage \(V_s\) is identified. @@ -403,7 +403,7 @@ All the identified dynamics of the six APA300ML (both when looking at the encode \caption{\label{fig:test_apa_frf_dynamics}Measured frequency response function from generated voltage \(u\) to the encoder displacement \(d_e\) (\subref{fig:test_apa_frf_encoder}) and to the force sensor voltage \(V_s\) (\subref{fig:test_apa_frf_force}) for the six APA300ML} \end{figure} \section{Non Minimum Phase Zero?} -\label{sec:org5d96397} +\label{sec:org49578de} \label{ssec:test_apa_non_minimum_phase} It was surprising to observe a non-minimum phase behavior for the zero on the transfer function from \(u\) to \(V_s\) (Figure \ref{fig:test_apa_frf_force}). @@ -433,7 +433,7 @@ However, this is not so important here as the zero is lightly damped (i.e. very \caption{\label{fig:test_apa_non_minimum_phase}Measurement of the anti-resonance found on the transfer function from \(u\) to \(V_s\). The coherence (\subref{fig:test_apa_non_minimum_phase_coherence}) is quite good around the anti-resonance frequency. The phase (\subref{fig:test_apa_non_minimum_phase_zoom}) shoes a non-minimum phase behavior.} \end{figure} \section{Effect of the resistor on the IFF Plant} -\label{sec:orge8ed591} +\label{sec:org8b60e04} \label{ssec:test_apa_resistance_sensor_stack} A resistor \(R \approx 80.6\,k\Omega\) is added in parallel with the sensor stack which has the effect to form a high pass filter with the capacitance of the piezoelectric stack (capacitance estimated at \(\approx 5\,\mu F\)). @@ -449,7 +449,7 @@ It is confirmed that the added resistor as the effect of adding an high pass fil \caption{\label{fig:test_apa_effect_resistance}Transfer function from \(u\) to \(V_s\) with and without the resistor \(R\) in parallel with the piezoelectric stack used as the force sensor} \end{figure} \section{Integral Force Feedback} -\label{sec:orge2d1f26} +\label{sec:orga8f1ff3} \label{ssec:test_apa_iff_locus} In order to implement the Integral Force Feedback strategy, the measured frequency response function from \(u\) to \(V_s\) (Figure \ref{fig:test_apa_frf_force}) is fitted using the transfer function shown in equation \eqref{eq:test_apa_iff_manual_fit}. @@ -506,7 +506,7 @@ The two obtained root loci are compared in Figure \ref{fig:test_apa_iff_root_loc \caption{\label{fig:test_apa_iff}Experimental results of applying Integral Force Feedback to the APA300ML. Obtained damped plant (\subref{fig:test_apa_identified_damped_plants}) and Root Locus (\subref{fig:test_apa_iff_root_locus})} \end{figure} \chapter{APA300ML - 2 Degrees of Freedom Model} -\label{sec:org42297a7} +\label{sec:org4cdbff1} \label{sec:test_apa_model_2dof} In this section, a simscape model (Figure \ref{fig:test_apa_bench_model}) of the measurement bench is used to compare the model of the APA with the measured frequency response functions. @@ -521,7 +521,7 @@ The obtained model dynamics is compared with the measurements in Section \ref{ss \caption{\label{fig:test_apa_bench_model}Screenshot of the Simscape model} \end{figure} \section{Two Degrees of Freedom APA Model} -\label{sec:org97d98f4} +\label{sec:org5d75a3a} \label{ssec:test_apa_2dof_model} The model of the amplified piezoelectric actuator is shown in Figure \ref{fig:test_apa_2dof_model}. @@ -548,7 +548,7 @@ Such simple model has some limitations: \caption{\label{fig:test_apa_2dof_model}Schematic of the two degrees of freedom model of the APA300ML, adapted from \cite{souleille18_concep_activ_mount_space_applic}} \end{figure} \section{Tuning of the APA model} -\label{sec:org29ff205} +\label{sec:org10fafb5} \label{ssec:test_apa_2dof_model_tuning} 9 parameters (\(m\), \(k_1\), \(c_1\), \(k_e\), \(c_e\), \(k_a\), \(c_a\), \(g_s\) and \(g_a\)) have to be tuned such that the dynamics of the model (Figure \ref{fig:test_apa_2dof_model_simscape}) well represents the identified dynamics in Section \ref{sec:test_apa_dynamics}. @@ -607,7 +607,7 @@ The obtained parameters of the model shown in Figure \ref{fig:test_apa_2dof_mode \end{table} \section{Obtained Dynamics} -\label{sec:orgbff057f} +\label{sec:org0831884} \label{ssec:test_apa_2dof_model_result} The dynamics of the two degrees of freedom model of the APA300ML is now extracted using optimized parameters (listed in Table \ref{tab:test_apa_2dof_parameters}) from the Simscape model. @@ -631,7 +631,7 @@ This indicates that this model represents well the axial dynamics of the APA300M \caption{\label{fig:test_apa_2dof_comp_frf}Comparison of the measured frequency response functions and the identified dynamics from the 2DoF model of the APA300ML. Both for the dynamics from \(u\) to \(d_e\) (\subref{fig:test_apa_2dof_comp_frf_enc}) (\subref{fig:test_apa_2dof_comp_frf_force}) and from \(u\) to \(V_s\) (\subref{fig:test_apa_2dof_comp_frf_force})} \end{figure} \chapter{APA300ML - Super Element} -\label{sec:org703026b} +\label{sec:org8292e07} \label{sec:test_apa_model_flexible} In this section, a \emph{super element} of the APA300ML is computed using a finite element software\footnote{Ansys\textsuperscript{\textregistered} was used}. @@ -651,7 +651,7 @@ It will be used to measure the strain experience by this stack, and model the se \caption{\label{fig:test_apa_super_element_simscape}Finite Element Model of the APA300ML with ``remotes points'' on the left. Simscape model with included ``Reduced Order Flexible Solid'' on the right.} \end{figure} \section{Identification of the Actuator and Sensor constants} -\label{sec:org1fc96a6} +\label{sec:org28294e9} \label{ssec:test_apa_flexible_ga_gs} Once the APA300ML \emph{super element} is included in the Simscape model, the transfer function from \(F_a\) to \(d_L\) and \(d_e\) can be extracted. @@ -694,7 +694,7 @@ From these parameters, \(g_s = 5.1\,V/\mu m\) and \(g_a = 26\,N/V\) were obtaine \end{table} \section{Comparison of the obtained dynamics} -\label{sec:orgd657b0f} +\label{sec:org14d2335} \label{ssec:test_apa_flexible_comp_frf} The obtained dynamics using the \emph{super element} with the tuned ``sensor gain'' and ``actuator gain'' are compared with the experimentally identified frequency response functions in Figure \ref{fig:test_apa_super_element_comp_frf}. @@ -719,20 +719,27 @@ Using this simple test bench, it can be concluded that the \emph{super element} \caption{\label{fig:test_apa_super_element_comp_frf}Comparison of the measured frequency response functions and the identified dynamics from the ``flexible'' model of the APA300ML. Both for the dynamics from \(u\) to \(d_e\) (\subref{fig:test_apa_2dof_comp_frf_enc}) (\subref{fig:test_apa_2dof_comp_frf_force}) and from \(u\) to \(V_s\) (\subref{fig:test_apa_2dof_comp_frf_force})} \end{figure} \chapter{Conclusion} -\label{sec:org0ba1df7} +\label{sec:org10e068b} \label{sec:test_apa_conclusion} -The main characteristics of the APA300ML such as hysteresis and axial stiffness have been measured and were found to comply with the specifications. +In this study, the received amplified piezoelectric actuators ``APA300ML'' have been characterized to make sure they are fulfilling all the requirements determined during the detailed design phase. -The dynamics of the received APA were measured and found to all be identical (Figure \ref{fig:test_apa_frf_dynamics}). -Even tough a non-minimum zero was observed on the transfer function from \(u\) to \(V_s\) (Figure \ref{fig:test_apa_non_minimum_phase}), it was not found to be problematic as large amount of damping could be added using the integral force feedback strategy (Figure \ref{fig:test_apa_iff}). +Geometrical features such as the flatness of its interfaces, electrical capacitance and achievable strokes were measured in Section \ref{sec:test_apa_basic_meas}. +These simple measurements allowed for early detection of a manufacturing defect in one of the APA300ML. +Then in Section \ref{sec:test_apa_dynamics}, using a dedicated test bench, the dynamics of all the APA300ML were measured and were found to all match very well (Figure \ref{fig:test_apa_frf_dynamics}). +This consistency indicates good manufacturing tolerances, facilitating the modeling and control of the nano-hexapod. +Although a non-minimum zero was identified in the transfer function from \(u\) to \(V_s\) (Figure \ref{fig:test_apa_non_minimum_phase}), it was found not to be problematic as large amount of damping could be added using the integral force feedback strategy (Figure \ref{fig:test_apa_iff}). +Then, two different models were used to represent the APA300ML dynamics. +In Section \ref{sec:test_apa_model_2dof}, a simple two degrees of freedom mass-spring-damper model was presented and tuned based on the measured dynamics. +After following a tuning procedure (see Section \ref{ssec:test_apa_2dof_model_tuning}), the model dynamics was shown to match very well with the experiment. +However, it is important to note that this model only represents the axial dynamics of the actuators, assuming infinite stiffness in other directions. -\begin{itemize} -\item Compare 2DoF and FEM models (usefulness of the two) -\item Good match between all the APA: will simplify the modeling and control of the nano-hexapod -\item No advantage of the FEM model here (as only uniaxial behavior is checked), but may be useful later -\end{itemize} +In Section \ref{sec:test_apa_model_flexible}, a \emph{super element} extracted from a finite element model was used to model the APA300ML. +This time, the \emph{super element} represents the dynamics of the APA300ML in all directions. +However, only the axial dynamics could be compared with the experimental results yielding a good match. +The benefit of employing this model over the two degrees of freedom model is not immediately apparent due to its increased complexity and the larger number of model states involved. +Nonetheless, the \emph{super element} model's value will become clear in subsequent sections, when its capacity to accurately model the APA300ML's flexibility across various directions will be important. \printbibliography[heading=bibintoc,title={Bibliography}] \end{document}