diff --git a/matlab/index.org b/matlab/index.org index d2ad407..059a265 100644 --- a/matlab/index.org +++ b/matlab/index.org @@ -72,6 +72,7 @@ Based on the Figure [[fig:rotating_xy_platform]], the equations of motions are: \bm{G}_d \begin{bmatrix} F_u \\ F_v \end{bmatrix} \end{equation} +Where $\bm{G}_d$ is a $2 \times 2$ transfer function matrix. \begin{equation} \begin{bmatrix} d_u \\ d_v \end{bmatrix} = diff --git a/paper/paper.org b/paper/paper.org index 02ab2d9..262a917 100644 --- a/paper/paper.org +++ b/paper/paper.org @@ -1,4 +1,4 @@ -#+TITLE: Vibration control of a rotating Stewart platform +#+TITLE: Active Damping of Rotating Positioning Platforms :DRAWER: #+LATEX_CLASS: ISMA_USD2020 #+OPTIONS: toc:nil @@ -53,20 +53,42 @@ * Introduction <> +*** Establish the importance of the research topic :ignore: +# Active Damping + Rotating Systems +*** Applications of active damping :ignore: +# Link to previous paper / tomography -* Theory -<> +cite:dehaeze18_sampl_stabil_for_tomog_exper -** Rotating Positioning Stage +*** Current active damping techniques :ignore: +# IFF, DVF -# Description of the system +*** Describe a gap in the research :ignore: +# No literature on rotating systems => gyroscopic effects + +*** Describe the paper itself / the problem which is addressed :ignore: + +*** Introduce Each part of the paper :ignore: + +* System Under Study +** Rotating Positioning Platform +# Simplest system where gyroscopic forces can be studied +Consider the rotating X-Y stage of Figure [[fig:rotating_xy_platform]]. + +# Present the system, parameters, assumptions + +# Small displacements + +# Constant rotating speed + +# Explain the frames (inertial frame x,y, rotating frame u,v) - $k$: Actuator's Stiffness [N/m] - $m$: Payload's mass [kg] -- $\omega_0 = \sqrt{\frac{k}{m}}$: Resonance of the (non-rotating) mass-spring system [rad/s] - $\Omega = \dot{\theta}$: rotation speed [rad/s] - +- $F_u$, $F_v$ +- $d_u$, $d_v$ #+name: fig:rotating_xy_platform #+caption: Figure caption @@ -74,34 +96,96 @@ [[file:figs/rotating_xy_platform.pdf]] +#+name: fig:cedrat_xy25xs +#+caption: Figure caption +#+attr_latex: :width 0.5\linewidth +[[file:figs/cedrat_xy25xs.jpg]] + ** Equation of Motion +The system has two degrees of freedom and is thus fully described by the generalized coordinates $u$ and $v$. Let's express the kinetic energy $T$ and the potential energy $V$ of the mass $m$ (neglecting the rotational energy): + +Dissipation function $R$ +Kinetic energy $T$ +Potential energy $V$ #+name: eq:energy_inertial_frame \begin{subequations} \begin{align} - T & = \frac{1}{2} m \left( \dot{x}^2 + \dot{y}^2 \right) \\ - R & = \frac{1}{2} c \left( \dot{x}^2 + \dot{y}^2 \right) \\ - V & = \frac{1}{2} k \left( x^2 + y^2 \right) + T & = \frac{1}{2} m \left( \left( \dot{u} - \Omega v \right)^2 + \left( \dot{v} + \Omega u \right)^2 \right) \\ + R & = \frac{1}{2} c \left( \dot{u}^2 + \dot{v}^2 \right) \\ + V & = \frac{1}{2} k \left( u^2 + v^2 \right) \end{align} \end{subequations} The Lagrangian is the kinetic energy minus the potential energy: #+name: eq:lagrangian_inertial_frame \begin{equation} -L = T-V = \frac{1}{2} m \left( \dot{x}^2 + \dot{y}^2 \right) - \frac{1}{2} k \left( x^2 + y^2 \right) +L = T - V \end{equation} -The external forces applied to the mass are: +From the Lagrange's equations of the second kind eqref:eq:lagrange_second_kind, the equation of motion eqref:eq:eom_mixed is obtained ($q_1 = u$, $q_2 = v$). +\begin{equation} + \frac{d}{dt} \left( \frac{\partial L}{\partial \dot{q}_i} \right) + \frac{\partial D}{\partial \dot{q}_i} - \frac{\partial L}{\partial q_i} = Q_i +\end{equation} + +\begin{equation} + \frac{d}{dt} \left( \frac{\partial T}{\partial \dot{q}_i} \right) - \frac{\partial T}{\partial q_i} + \frac{\partial R}{\partial \dot{q}_i} - \frac{\partial V}{\partial q_i} = Q_i +\end{equation} + +with $Q_i$ is the generalized force associated with the generalized variable $q_i$ ($F_u$ and $F_v$). + \begin{subequations} \begin{align} - F_{\text{ext}, x} &= F_u \cos{\theta} - F_v \sin{\theta}\\ - F_{\text{ext}, y} &= F_u \sin{\theta} + F_v \cos{\theta} + m \ddot{u} + c \dot{u} + ( k - m \Omega ) u &= F_u + 2 m \Omega \dot{v} \\ + m \ddot{v} + c \dot{v} + ( k \underbrace{-\,m \Omega}_{\text{Centrif.}} ) v &= F_v \underbrace{-\,2 m \Omega \dot{u}}_{\text{Coriolis}} + \end{align} +\end{subequations} + +# Explain Gyroscopic effects + + + + +# Laplace Domain + +\begin{subequations} + \begin{align} + u &= \frac{ms^2 + cs + k - m \Omega^2}{\left( m s^2 + cs + k - m \Omega^2 \right)^2 + \left( 2 m \Omega s \right)^2} F_u + \frac{2 m \Omega s}{\left( m s^2 + cs + k - m \Omega^2 \right)^2 + \left( 2 m \Omega s \right)^2} F_v \\ + v &= \frac{-2 m \Omega s}{\left( m s^2 + cs + k - m \Omega^2 \right)^2 + \left( 2 m \Omega s \right)^2} F_u + \frac{ms^2 + cs + k - m \Omega^2}{\left( m s^2 + cs + k - m \Omega^2 \right)^2 + \left( 2 m \Omega s \right)^2} F_v + \end{align} +\end{subequations} + +# Change of variables +\begin{equation} +\begin{bmatrix} d_u \\ d_v \end{bmatrix} = +\bm{G}_d +\begin{bmatrix} F_u \\ F_v \end{bmatrix} +\end{equation} +Where $\bm{G}_d$ is a $2 \times 2$ transfer function matrix. + +\begin{equation} +\bm{G}_d = \frac{1}{k} \frac{1}{G_{dp}} +\begin{bmatrix} + G_{dz} & G_{dc} \\ + -G_{dc} & G_{dz} +\end{bmatrix} +\end{equation} +With: +\begin{subequations} + \begin{align} + G_{dp} &= \left( \frac{s^2}{{\omega_0}^2} + 2 \xi \frac{s}{\omega_0} + 1 - \frac{{\Omega}^2}{{\omega_0}^2} \right)^2 + \left( 2 \frac{\Omega}{\omega_0} \frac{s}{\omega_0} \right)^2 \\ + G_{dz} &= \frac{s^2}{{\omega_0}^2} + 2 \xi \frac{s}{\omega_0} + 1 - \frac{{\Omega}^2}{{\omega_0}^2} \\ + G_{dc} &= 2 \frac{\Omega}{\omega_0} \frac{s}{\omega_0} \end{align} \end{subequations} -From the Lagrange's equations of the second kind eqref:eq:lagrange_second_kind, the equation of motion eqref:eq:eom_mixed is obtained. + +- $\omega_0 = \sqrt{\frac{k}{m}}$: Natural frequency of the mass-spring system in $\si{\radian/\s}$ +- $\xi$ damping ratio + + #+name: eq:lagrange_second_kind \begin{equation} @@ -186,18 +270,104 @@ As the rotation speed increases, one of the two resonant frequency goes to lower #+name: fig:campbell_diagram #+caption: Campbell Diagram +#+attr_latex: :scale 1 [[file:figs/campbell_diagram.pdf]] # Bode Plots for different ratio wr/w0 The magnitude of the coupling terms are increasing with the rotation speed. +#+name: fig:plant_compare_rotating_speed +#+caption: Caption +#+attr_latex: :scale 1 +[[file:figs/plant_compare_rotating_speed.pdf]] -** Integral Force Feedback +* Integral Force Feedback +** Control Schematic +** Equations -** Direct Velocity Feedback +** Plant Dynamics +#+name: fig:root_locus_pure_iff +#+caption: Figure caption +#+attr_latex: :scale 1 +[[file:figs/root_locus_pure_iff.pdf]] + +** Physical Interpretation + +* Integral Force Feedback with Low Pass Filters + +#+name: fig:loop_gain_modified_iff +#+caption: Figure caption +#+attr_latex: :scale 1 +[[file:figs/loop_gain_modified_iff.pdf]] + +#+name: fig:root_locus_modified_iff +#+caption: Figure caption +#+attr_latex: :scale 1 +[[file:figs/root_locus_modified_iff_bis.pdf]] + +#+name: fig:root_locus_wi_modified_iff +#+caption: Figure caption +#+attr_latex: :scale 1 +[[file:figs/root_locus_wi_modified_iff.pdf]] + +* Integral Force Feedback with Parallel Springs + +#+name: fig:rotating_xy_platform_springs +#+caption: Figure caption +#+attr_latex: :scale 1 +[[file:figs/rotating_xy_platform_springs.pdf]] + +#+name: fig:plant_iff_kp +#+caption: Figure caption +#+attr_latex: :scale 1 +[[file:figs/plant_iff_kp.pdf]] + +#+name: fig:root_locus_iff_kps +#+caption: Figure caption +#+attr_latex: :scale 1 +[[file:figs/root_locus_iff_kps.pdf]] + +#+name: fig:root_locus_iff_kp_bis +#+caption: Figure caption +#+attr_latex: :scale 1 +[[file:figs/root_locus_iff_kp_bis.pdf]] + +#+name: fig:root_locus_opt_gain_iff_kp +#+caption: Figure caption +#+attr_latex: :scale 1 +[[file:figs/root_locus_opt_gain_iff_kp.pdf]] + +#+name: fig:plant_iff_compare_rotating_speed +#+caption: Figure caption +#+attr_latex: :scale 1 +[[file:figs/plant_iff_compare_rotating_speed.pdf]] + +* Direct Velocity Feedback + +#+name: fig:root_locus_dvf +#+caption: Figure caption +#+attr_latex: :scale 1 +[[file:figs/root_locus_dvf.pdf]] + +* Comparison of the Proposed Active Damping Techniques + +#+name: fig:comp_root_locus +#+caption: Figure caption +#+attr_latex: :scale 1 +[[file:figs/comp_root_locus.pdf]] + +#+name: fig:comp_compliance +#+caption: Figure caption +#+attr_latex: :scale 1 +[[file:figs/comp_compliance.pdf]] + +#+name: fig:comp_transmissibility +#+caption: Figure caption +#+attr_latex: :scale 1 +[[file:figs/comp_transmissibility.pdf]] * Conclusion <> diff --git a/paper/paper.pdf b/paper/paper.pdf index 18fb306..0d4ce84 100644 Binary files a/paper/paper.pdf and b/paper/paper.pdf differ diff --git a/paper/paper.tex b/paper/paper.tex index 094fd5b..8eec7a7 100644 --- a/paper/paper.tex +++ b/paper/paper.tex @@ -1,4 +1,4 @@ -% Created 2020-06-08 lun. 11:40 +% Created 2020-06-22 lun. 13:27 % Intended LaTeX compiler: pdflatex \documentclass{ISMA_USD2020} \usepackage[utf8]{inputenc} @@ -31,15 +31,9 @@ \affil[1] {Precision Mechatronics Laboratory\NewLineAffil University of Liege, Belgium \NewAffil} \affil[2] {BEAMS Department\NewLineAffil Free University of Brussels, Belgium \NewAffil} \affil[3] {European Synchrotron Radiation Facility \NewLineAffil Grenoble, France e-mail: \textbf{thomas.dehaeze@esrf.fr}} +\bibliographystyle{IEEEtran} \date{} -\title{Vibration control of a rotating Stewart platform} -\hypersetup{ - pdfauthor={}, - pdftitle={Vibration control of a rotating Stewart platform}, - pdfkeywords={}, - pdfsubject={}, - pdfcreator={Emacs 27.0.91 (Org mode 9.4)}, - pdflang={English}} +\title{Active Damping of Rotating Positioning Platforms} \begin{document} \maketitle @@ -49,16 +43,23 @@ } \section{Introduction} -\label{sec:org335669b} +\label{sec:orgd20252d} \label{sec:introduction} +\cite{dehaeze18_sampl_stabil_for_tomog_exper} +\section{System Under Study} +\label{sec:orgacbe1ae} +\subsection{Rotating Positioning Platform} +\label{sec:org07e4fc8} +Consider the rotating X-Y stage of Figure \ref{fig:rotating_xy_platform}. -\section{Theory} -\label{sec:org8b756e7} -\label{sec:theory} - -\subsection{Rotating Positioning Stage} -\label{sec:orgbf4a596} +\begin{itemize} +\item \(k\): Actuator's Stiffness [N/m] +\item \(m\): Payload's mass [kg] +\item \(\Omega = \dot{\theta}\): rotation speed [rad/s] +\item \(F_u\), \(F_v\) +\item \(d_u\), \(d_v\) +\end{itemize} \begin{figure}[htbp] \centering @@ -67,39 +68,304 @@ \end{figure} +\begin{figure}[htbp] +\centering +\includegraphics[width=0.5\linewidth]{figs/cedrat_xy25xs.jpg} +\caption{\label{fig:cedrat_xy25xs}Figure caption} +\end{figure} + \subsection{Equation of Motion} -\label{sec:orgaa8880a} +\label{sec:orgac1a52a} +The system has two degrees of freedom and is thus fully described by the generalized coordinates \(u\) and \(v\). -Let's express the kinetic energy \(T\) and the potential energy \(V\) of the mass \(m\): -\begin{align} +Let's express the kinetic energy \(T\) and the potential energy \(V\) of the mass \(m\) (neglecting the rotational energy): + +Dissipation function \(R\) +Kinetic energy \(T\) +Potential energy \(V\) +\begin{subequations} \label{eq:energy_inertial_frame} -T & = \frac{1}{2} m \left( \dot{x}^2 + \dot{y}^2 \right) \\ -V & = \frac{1}{2} k \left( x^2 + y^2 \right) -\end{align} + \begin{align} + T & = \frac{1}{2} m \left( \left( \dot{u} - \Omega v \right)^2 + \left( \dot{v} + \Omega u \right)^2 \right) \\ + R & = \frac{1}{2} c \left( \dot{u}^2 + \dot{v}^2 \right) \\ + V & = \frac{1}{2} k \left( u^2 + v^2 \right) + \end{align} +\end{subequations} -The Lagrangian is the kinetic energy minus the potential energy. +The Lagrangian is the kinetic energy minus the potential energy: \begin{equation} \label{eq:lagrangian_inertial_frame} -L = T-V = \frac{1}{2} m \left( \dot{x}^2 + \dot{y}^2 \right) - \frac{1}{2} k \left( x^2 + y^2 \right) +L = T - V \end{equation} +From the Lagrange's equations of the second kind \eqref{eq:lagrange_second_kind}, the equation of motion \eqref{eq:eom_mixed} is obtained (\(q_1 = u\), \(q_2 = v\)). +\begin{equation} + \frac{d}{dt} \left( \frac{\partial L}{\partial \dot{q}_i} \right) + \frac{\partial D}{\partial \dot{q}_i} - \frac{\partial L}{\partial q_i} = Q_i +\end{equation} -\subsection{Integral Force Feedback} -\label{sec:org754b644} +\begin{equation} + \frac{d}{dt} \left( \frac{\partial T}{\partial \dot{q}_i} \right) - \frac{\partial T}{\partial q_i} + \frac{\partial R}{\partial \dot{q}_i} - \frac{\partial V}{\partial q_i} = Q_i +\end{equation} + +with \(Q_i\) is the generalized force associated with the generalized variable \(q_i\) (\(F_u\) and \(F_v\)). + +\begin{subequations} + \begin{align} + m \ddot{u} + c \dot{u} + ( k - m \Omega ) u &= F_u + 2 m \Omega \dot{v} \\ + m \ddot{v} + c \dot{v} + ( k \underbrace{-\,m \Omega}_{\text{Centrif.}} ) v &= F_v \underbrace{-\,2 m \Omega \dot{u}}_{\text{Coriolis}} + \end{align} +\end{subequations} + +\begin{subequations} + \begin{align} + u &= \frac{ms^2 + cs + k - m \Omega^2}{\left( m s^2 + cs + k - m \Omega^2 \right)^2 + \left( 2 m \Omega s \right)^2} F_u + \frac{2 m \Omega s}{\left( m s^2 + cs + k - m \Omega^2 \right)^2 + \left( 2 m \Omega s \right)^2} F_v \\ + v &= \frac{-2 m \Omega s}{\left( m s^2 + cs + k - m \Omega^2 \right)^2 + \left( 2 m \Omega s \right)^2} F_u + \frac{ms^2 + cs + k - m \Omega^2}{\left( m s^2 + cs + k - m \Omega^2 \right)^2 + \left( 2 m \Omega s \right)^2} F_v + \end{align} +\end{subequations} + +\begin{equation} +\begin{bmatrix} d_u \\ d_v \end{bmatrix} = +\bm{G}_d +\begin{bmatrix} F_u \\ F_v \end{bmatrix} +\end{equation} +Where \(\bm{G}_d\) is a \(2 \times 2\) transfer function matrix. + +\begin{equation} +\bm{G}_d = \frac{1}{k} \frac{1}{G_{dp}} +\begin{bmatrix} + G_{dz} & G_{dc} \\ + -G_{dc} & G_{dz} +\end{bmatrix} +\end{equation} +With: +\begin{subequations} + \begin{align} + G_{dp} &= \left( \frac{s^2}{{\omega_0}^2} + 2 \xi \frac{s}{\omega_0} + 1 - \frac{{\Omega}^2}{{\omega_0}^2} \right)^2 + \left( 2 \frac{\Omega}{\omega_0} \frac{s}{\omega_0} \right)^2 \\ + G_{dz} &= \frac{s^2}{{\omega_0}^2} + 2 \xi \frac{s}{\omega_0} + 1 - \frac{{\Omega}^2}{{\omega_0}^2} \\ + G_{dc} &= 2 \frac{\Omega}{\omega_0} \frac{s}{\omega_0} + \end{align} +\end{subequations} -\subsection{Direct Velocity Feedback} -\label{sec:org9cbf82a} +\begin{itemize} +\item \(\omega_0 = \sqrt{\frac{k}{m}}\): Natural frequency of the mass-spring system in \(\si{\radian/\s}\) +\item \(\xi\) damping ratio +\end{itemize} + + + +\begin{equation} +\label{eq:lagrange_second_kind} + \frac{d}{dt} \left( \frac{\partial L}{\partial \dot{q}_j} \right) = \frac{\partial L}{\partial q_j} +\end{equation} + +\begin{subequations} +\label{eq:eom_mixed} + \begin{align} + m\ddot{x} + kx = F_u \cos{\theta} - F_v \sin{\theta}\\ + m\ddot{y} + ky = F_u \sin{\theta} + F_v \cos{\theta} + \end{align} +\end{subequations} + +Performing the change coordinates from \((x, y)\) to \((d_x, d_y, \theta)\): +\begin{subequations} + \begin{align} + x & = d_u \cos{\theta} - d_v \sin{\theta}\\ + y & = d_u \sin{\theta} + d_v \cos{\theta} + \end{align} +\end{subequations} + +Gives +\begin{subequations} +\label{eq:oem_coupled} + \begin{align} + m \ddot{d_u} + (k - m\dot{\theta}^2) d_u &= F_u + 2 m\dot{d_v}\dot{\theta} + m d_v\ddot{\theta} \label{eq:du_coupled} \\ + m \ddot{d_v} + (k \underbrace{-\ m\dot{\theta}^2}_{\text{Centrif.}}) d_v &= F_v \underbrace{-\ 2 m\dot{d_u}\dot{\theta}}_{\text{Coriolis}} \underbrace{-\ m d_u\ddot{\theta}}_{\text{Euler}} \label{eq:dv_coupled} + \end{align} +\end{subequations} + +We obtain two differential equations that are coupled through: +\begin{itemize} +\item \textbf{Euler forces}: \(m d_v \ddot{\theta}\) +\item \textbf{Coriolis forces}: \(2 m \dot{d_v} \dot{\theta}\) +\end{itemize} + +Without the coupling terms, each equation is the equation of a one degree of freedom mass-spring system with mass \(m\) and stiffness \(k- m\dot{\theta}^2\). +Thus, the term \(- m\dot{\theta}^2\) acts like a negative stiffness (due to \textbf{centrifugal forces}). + +\subsection{Constant Rotating Speed} +\label{sec:org47aaeee} +To simplify, let's consider a constant rotating speed \(\dot{\theta} = \Omega\) and thus \(\ddot{\theta} = 0\). + +\begin{equation} +\label{eq:coupledplant} +\begin{bmatrix} d_u \\ d_v \end{bmatrix} = +\frac{1}{(m s^2 + (k - m{\omega_0}^2))^2 + (2 m {\omega_0} s)^2} +\begin{bmatrix} + ms^2 + (k-m{\omega_0}^2) & 2 m \omega_0 s \\ + -2 m \omega_0 s & ms^2 + (k-m{\omega_0}^2) \\ +\end{bmatrix} +\begin{bmatrix} F_u \\ F_v \end{bmatrix} +\end{equation} + +\begin{equation} +\label{eq:coupled_plant} +\begin{bmatrix} d_u \\ d_v \end{bmatrix} = +\frac{\frac{1}{k}}{\left( \frac{s^2}{{\omega_0}^2} + (1 - \frac{{\Omega}^2}{{\omega_0}^2}) \right)^2 + \left( 2 \frac{{\Omega} s}{{\omega_0}^2} \right)^2} +\begin{bmatrix} + \frac{s^2}{{\omega_0}^2} + 1 - \frac{{\Omega}^2}{{\omega_0}^2} & 2 \frac{\Omega s}{{\omega_0}^2} \\ + -2 \frac{\Omega s}{{\omega_0}^2} & \frac{s^2}{{\omega_0}^2} + 1 - \frac{{\Omega}^2}{{\omega_0}^2} \\ +\end{bmatrix} +\begin{bmatrix} F_u \\ F_v \end{bmatrix} +\end{equation} + +When the rotation speed is null, the coupling terms are equal to zero and the diagonal terms corresponds to one degree of freedom mass spring system. +\begin{equation} +\label{eq:coupled_plant_no_rot} +\begin{bmatrix} d_u \\ d_v \end{bmatrix} = +\frac{\frac{1}{k}}{\frac{s^2}{{\omega_0}^2} + 1} +\begin{bmatrix} + 1 & 0 \\ + 0 & 1 +\end{bmatrix} +\begin{bmatrix} F_u \\ F_v \end{bmatrix} +\end{equation} + +When the rotation speed in not null, the resonance frequency is duplicated into two pairs of complex conjugate poles. +As the rotation speed increases, one of the two resonant frequency goes to lower frequencies as the other one goes to higher frequencies (Figure \ref{fig:campbell_diagram}). + +\begin{figure}[htbp] +\centering +\includegraphics[scale=1]{figs/campbell_diagram.pdf} +\caption{\label{fig:campbell_diagram}Campbell Diagram} +\end{figure} + +The magnitude of the coupling terms are increasing with the rotation speed. + +\begin{figure}[htbp] +\centering +\includegraphics[scale=1]{figs/plant_compare_rotating_speed.pdf} +\caption{\label{fig:plant_compare_rotating_speed}Caption} +\end{figure} + +\section{Integral Force Feedback} +\label{sec:org78c2eab} +\subsection{Control Schematic} +\label{sec:org6a00238} + +\subsection{Equations} +\label{sec:org5480f1b} + +\subsection{Plant Dynamics} +\label{sec:orgbb0952e} + +\begin{figure}[htbp] +\centering +\includegraphics[scale=1]{figs/root_locus_pure_iff.pdf} +\caption{\label{fig:root_locus_pure_iff}Figure caption} +\end{figure} + +\subsection{Physical Interpretation} +\label{sec:orgdb25e2c} + +\section{Integral Force Feedback with Low Pass Filters} +\label{sec:org2985d35} + +\begin{figure}[htbp] +\centering +\includegraphics[scale=1]{figs/loop_gain_modified_iff.pdf} +\caption{\label{fig:loop_gain_modified_iff}Figure caption} +\end{figure} + +\begin{figure}[htbp] +\centering +\includegraphics[scale=1]{figs/root_locus_modified_iff_bis.pdf} +\caption{\label{fig:root_locus_modified_iff}Figure caption} +\end{figure} + +\begin{figure}[htbp] +\centering +\includegraphics[scale=1]{figs/root_locus_wi_modified_iff.pdf} +\caption{\label{fig:root_locus_wi_modified_iff}Figure caption} +\end{figure} + +\section{Integral Force Feedback with Parallel Springs} +\label{sec:orga4142a5} + +\begin{figure}[htbp] +\centering +\includegraphics[scale=1]{figs/rotating_xy_platform_springs.pdf} +\caption{\label{fig:rotating_xy_platform_springs}Figure caption} +\end{figure} + +\begin{figure}[htbp] +\centering +\includegraphics[scale=1]{figs/plant_iff_kp.pdf} +\caption{\label{fig:plant_iff_kp}Figure caption} +\end{figure} + +\begin{figure}[htbp] +\centering +\includegraphics[scale=1]{figs/root_locus_iff_kps.pdf} +\caption{\label{fig:root_locus_iff_kps}Figure caption} +\end{figure} + +\begin{figure}[htbp] +\centering +\includegraphics[scale=1]{figs/root_locus_iff_kp_bis.pdf} +\caption{\label{fig:root_locus_iff_kp_bis}Figure caption} +\end{figure} + +\begin{figure}[htbp] +\centering +\includegraphics[scale=1]{figs/root_locus_opt_gain_iff_kp.pdf} +\caption{\label{fig:root_locus_opt_gain_iff_kp}Figure caption} +\end{figure} + +\begin{figure}[htbp] +\centering +\includegraphics[scale=1]{figs/plant_iff_compare_rotating_speed.pdf} +\caption{\label{fig:plant_iff_compare_rotating_speed}Figure caption} +\end{figure} + +\section{Direct Velocity Feedback} +\label{sec:org6a1be4f} + +\begin{figure}[htbp] +\centering +\includegraphics[scale=1]{figs/root_locus_dvf.pdf} +\caption{\label{fig:root_locus_dvf}Figure caption} +\end{figure} + +\section{Comparison of the Proposed Active Damping Techniques} +\label{sec:orga9658c0} + +\begin{figure}[htbp] +\centering +\includegraphics[scale=1]{figs/comp_root_locus.pdf} +\caption{\label{fig:comp_root_locus}Figure caption} +\end{figure} + +\begin{figure}[htbp] +\centering +\includegraphics[scale=1]{figs/comp_compliance.pdf} +\caption{\label{fig:comp_compliance}Figure caption} +\end{figure} + +\begin{figure}[htbp] +\centering +\includegraphics[scale=1]{figs/comp_transmissibility.pdf} +\caption{\label{fig:comp_transmissibility}Figure caption} +\end{figure} \section{Conclusion} -\label{sec:org8d24de3} +\label{sec:orgcdf948f} \label{sec:conclusion} -\section{Acknowledgment} -\label{sec:orgb252937} +\section*{Acknowledgment} +\label{sec:org6c21e13} - -\bibliography{ref} +\bibliography{ref.bib} \end{document}