winter-day-2016-lecture.tex

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\title{Indoor positioning using smartphones}


%\subtitle
%{Presentation Subtitle} % (optional)

\author[Simo S\"arkk\"a]{Assoc.~Prof.~{\bf Simo S\"arkk\"a}}
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\institute[EEA Department]{\balert{EEA Department / ELEC@Aalto, Finland}} % (optional, but mostly needed)

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%\date[March 2, 2016]{\alert{Research Winter Day, March 2, 2016}}
\date{March 24, 2016}

%\subject{Talks}
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\begin{frame}
  \frametitle{Contents}
  \tableofcontents[pausesections]
  % You might wish to add the option [pausesections]
\end{frame}

\section{Motivation}

\begin{frame}
  \frametitle{Why indoor positioning is important}

  % guidance
  % IoT
  % fire brigade
  % medical personnell

  \begin{columns}
  \begin{column}{0.7\textwidth}
  \begin{itemize}[<+->]

%  \item Indoor positioning has \alert{applications} in various areas.

  \item {\em Shopping mall applications:}
    \begin{itemize}[<+->]  
  	\item \alert{Wayfinding} in \balert{shopping malls}.
	\item Wayfinding and navigation in \alert{garages}.
  	\item Targeted \alert{advertisement} and \balert{analytics}.
    \end{itemize}
  \item {\em Hospitals}:
    \begin{itemize}[<+->]  
      \item Tracking of \alert{patients}.
      \item Alerting of \alert{medical personnel}. 
      \item Positioning of \alert{wireless medical equipment}. 
    \end{itemize}
  \item {\em Internet-of-things (IoT):}
    \begin{itemize}[<+->]    
      \item Positioning of \alert{IoT devices}.
      \item \alert{Ad-doc network} formation.
    \end{itemize}
  \item {\em Safety and security:}
    \begin{itemize}[<+->]    
      \item Navigation in \alert{burning buildings}.
      \item \alert{Security personnel} tracking.
    \end{itemize}
  \end{itemize}
  \end{column}
  \begin{column}{0.3\textwidth}
  \includegraphics[width=0.8\columnwidth]{nurse_nav} \\
  \includegraphics[width=0.8\columnwidth]{IoT} \\
  \includegraphics[width=0.8\columnwidth]{fire}
  \end{column}
  \end{columns}
\end{frame}

\begin{frame}
  \frametitle{Why indoor positioning is hard}

  % - 1m accuracy requirement
  % - GPS does not work indoors
  % - Different floors are significant
  \begin{columns}
  \begin{column}{0.7\textwidth}
  \begin{itemize}[<+->]       
  \item \alert{GPS does not work indoors} -- nor any other satellite navigation system.
  \item The \alert{accuracy requirement} is often \alert{1 meter}.
  \item \alert{Mobile phone network} positioning is not accurate enough.
  \item Accurate \alert{height} information is important (which floor).
  \item \alert{Indoor maps} can be challenging to obtain.
  \end{itemize}
  \end{column}
  \begin{column}{0.3\textwidth}
  \includegraphics[width=\columnwidth]{nogps} \\
  \includegraphics[width=\columnwidth]{accuracy} \\
  \includegraphics[width=\columnwidth]{floor}
  \end{column}
  \end{columns}
\end{frame}

\begin{frame}
  \frametitle{Sensors in modern smartphones}

  \begin{columns}
  \begin{column}{0.6\textwidth}
  \begin{itemize}[<+->]       
  \item \alert{GPS/GNSS receiver} for (outdoors) satellite positioning.
  \item \alert{Accelerometer and gyroscope} measure the local moment and rotation.
  \item \alert{WiFi, Bluetooth, and 3G/4G/5G} devices measure radio signals.
  \item \alert{Magnetometer} (compass) measures the local magnetic field direction.
  \item \alert{Barometer} measures the local pressure (gives information on height).
  \item \alert{Camera} measures the optical properties of the environment (i.e. takes pictures).
  \end{itemize}
  \end{column}
  \begin{column}{0.4\textwidth}
  \includegraphics[width=\columnwidth]{smartphone}
  \end{column}
  \end{columns}
\end{frame}

\section{Indoor positioning methods}

\begin{frame}
  \frametitle{WiFi and beacon-based positioning}

  \begin{columns}
  \begin{column}{0.6\textwidth}
  \begin{itemize}[<+->]       
  \item \alert{WiFi and (Bluetooth) beacons} are often used for indoor positioning.
  \item Based on measuring strengths of \alert{radio transmitters in known locations}.
  \item Requires building a \alert{map of the radio environment}.
  \item \alert{Accuracy} is limited by \alert{local attenuation and device differences}.
  \item \alert{Radio maps} need to be \alert{updated} continuously -- can be labour-intensive.
  \end{itemize}
  \end{column}
  \begin{column}{0.4\textwidth}
  \includegraphics[width=\columnwidth]{floorplan} \\
  \vspace{2em}
  \includegraphics[width=\columnwidth]{wifimap}
  \end{column}
  \end{columns}
\end{frame}

\begin{frame}
  \frametitle{Magnetic positioning}

  \begin{columns}
  \begin{column}{0.6\textwidth}
  \begin{itemize}[<+->]       
  \item \alert{Magnetic positioning} utilizes \alert{local magnetic field variations} in buildings.
  \item Requires creating a \alert{map of the magnetic field variations}.
  \item Due to field ambiguity, needs to be combined with \alert{inertial navigation} and \alert{orientation tracking}.
  \item \alert{Locally accurate}, benefits from \alert{combining with WiFi/Beacon positioning}.
  \end{itemize}
  \end{column}
  \begin{column}{0.4\textwidth}
  \includegraphics[width=\columnwidth]{terrain-matching} \\
  \vspace{2em}
  \includegraphics[width=\columnwidth]{magnetic}
  \end{column}
  \end{columns}
\end{frame}

\section{Sensor fusion and SLAM}

\begin{frame}
  \frametitle{Inertial navigation, PDRs, and orientation tracking}

  \begin{columns}
  \begin{column}{0.6\textwidth}
  \begin{itemize}[<+->]       
  \item \alert{Acceleration and angular velocity} can be \alert{integrated} to give position and orientation.
  \item Unknown \alert{initial conditions and sensors drifts} cause problems.
  \item The \alert{known gravitation direction} helps in \alert{orientation tracking}.
  \item Accelerometer can also be used to \alert{detect steps} -- gives a measurement of \alert{speed/distance}.
  \item \alert{Barometer} can be used to for \alert{local height tracking}. 
  \item Best when \alert{combined} with \alert{radio and magnetic} positioning methods.
  \end{itemize}
  \end{column}
  \begin{column}{0.4\textwidth}
  \includegraphics[width=\columnwidth]{mobile2} \\
  \includegraphics[width=\columnwidth]{grav}
  \end{column}
  \end{columns}
\end{frame}

\begin{frame}
  \frametitle{Simultaneous localization and mapping (SLAM)}

  \begin{columns}
  \begin{column}{0.5\textwidth}
  \begin{itemize}[<+->]       
  \item In \alert{simultaneous localization and mapping (SLAM)} the radio/ magnetic
  map is created while positioning.
  \item Considerably \alert{harder} than \alert{separate mapping and positioning}.
  \item Typically based on detecting a \alert{return to known location}:
  \begin{itemize}[<+->]       
  \item We can do a \alert{loop closure} to confirm the traveled path.
  \item \alert{Inertial navigation} can be used to map a small unknown area at a time.
  \item Known wall locations provide \alert{constraints}.
  \end{itemize}
  \end{itemize}
  \end{column}
  \begin{column}{0.5\textwidth}
  \includegraphics[width=\columnwidth]{slam} \\
  \end{column}
  \end{columns}
\end{frame}



\begin{frame}
  \frametitle{Gaussian processes, Kalman and particle filtering}

  \begin{columns}
  \begin{column}{0.65\textwidth}
  \begin{itemize}[<+->]       
  \item \alert{WiFi, beacon, and magnetic maps} typically estimated using \alert{Gaussian processes} (GPs).
  \item GPs are \alert{machine learning tools} for \alert{learning} the field from noisy observations.
  \item \alert{Inertial sensor fusion} is often done using \alert{(extended) Kalman filters}.
  \item \alert{Sensor fusion} with \alert{radio and magnetic} often done with \alert{particle filters}.
  \item When combined, can be used for \alert{simultaneous localization and mapping (SLAM)}.
  \item Generally, \alert{multi-sensor processing} is treated as a (Bayesian) \alert{statistical inverse problem}.
  \end{itemize}
  \end{column}
  \begin{column}{0.35\textwidth}
  \includegraphics[width=\columnwidth]{TikZ-covariance-figure} \\
  \includegraphics[width=\columnwidth]{pf_est}
  \end{column}
  \end{columns}
\end{frame}


\section{Future insights and summary}

\begin{frame}
  \frametitle{Computer vision, future insights}

  \begin{columns}
  \begin{column}{0.51\textwidth}
  \begin{itemize}[<+->]
  \item \alert{Smartphone camera} can be used for determining the \alert{3D structure of indoor environment}.
  \item When \alert{combined with SLAM}, eliminates the need for floorplans -- and eases SLAM.
  \item Even better is to use a \alert{depth-camera, laser, or miniature radar}.
  \item Other \alert{improvement possibilities}:
  \begin{itemize}[<+->]
  \item Cooperative positioning.
  \item Other signals of opportunity.
  \item Modeling of human behaviour.
  \end{itemize}
  \end{itemize}
  \end{column}
  \begin{column}{0.49\textwidth}
  \includegraphics[width=\columnwidth]{pointcloud} \\
  \end{column}
  \end{columns}
\end{frame}

\begin{frame}
  \frametitle{Summary}

  \begin{itemize}[<+->]       
  \item \alert{Indoor positioning} has applications, e.g., in shopping malls, hospitals, internet-of-things, and security.
  \item Hard, because \alert{GPS does not work} indoors and the \alert{accuracy requirements} are tight.
  \item Smartphones have a number of sensors: \alert{radio, inertial, magnetic, and barometer sensors} (among others).
  \item Indoor positioning typically use \alert{WiFi, beacons, or magnetic field variations}.
  \item \alert{Inertial navigation, step counting, and barometer} can be combined with the methods.
  \item \alert{Simultaneous localization and mapping (SLAM)} methods build maps while positioning.
  \item Computational methods include \alert{Gaussian processes} together with \alert{Kalman and particle filters}.
  \end{itemize}
\end{frame}

\end{document}