fixed baraomter issue (skip first few readings due to sensor errors)
added new eval using shortest-path + plotting removed compiler warnings for clean-code fixed some minor issues added new TeX code and new graphics
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@@ -21,3 +21,6 @@
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mit pfad laeuft es falsch, weil die andere treppe kuerzer zum ziel ist und das wlan dort besser passt}
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\commentByFrank{zu grosser einfluss vom pfad ist also kein allheilmittel.. kann, wie beim treppenhaus, auch nach hinten los gehen}
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\commentByFrank{path1: bad start due to nearby AP and bad parameters (path-loss too high)}
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@@ -12,3 +12,9 @@
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\subsection{Weighting}
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\subsection{Pathfinding}
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\commentByFrank{describe the multi-path version}
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\commentByFrank{describe the single-path version}
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\commentByFrank{exp-dist for distance to the path. more distance = less-likely}
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\commentByFrank{lambda-factor controls the allowed deviation from the shortest-path}
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@@ -6,26 +6,41 @@
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preferred over absolute ones. However, due to noisy sensors \todo{cite oder grafik? je nach platz}, one
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single reading is not enough as a relative base. Harnessing the usual setup time of a navigation-system (
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route calculation, user checking the route) we use the average of all barometer readings during this
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timeframe as realtive base $\overline{\mPressure}$.
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timeframe as realtive base $\overline{\mObsPressure}$. However, it is often necessary to omit the first few
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sensors readings, as the sensor needs some time to settle and the estimated base would otherwise be far off
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the real values (see fig. \ref{fig:baroSetupError}). Besides, we use the system's setup time to estimate the
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sensors uncertainty $\sigma_\text{baro}$ for later use within the evaluation.
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During each transition from $\mStateVec_{t-1}$ to $\mStateVec_t$, the predicted pressure $\mStatePressure$ is
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adjusted according to the resulting $z$-change, if any:
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\begin{figure}
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\include{gfx/baro/baro_setup_issue}
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\caption{Sometimes the barometer provides erroneous \SI{}{\hpa} readings during the first seconds. Those
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need to be omitted before $\sigma_\text{baro}$ and $\overline{\mObsPressure}$ are estimated.}
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\label{fig:baroSetupError}
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\end{figure}
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During each transition from $\mStateVec_{t-1}$ to $\mStateVec_t$, we need a corresponding, relative pressure
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prediction $\mStatePressure$ which is adjusted according to the resulting $z$-change, if any:
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\begin{equation}
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\mState_{t}^{\mStatePressure} = \mState_{t-1}^{\mStatePressure} + \Delta z \cdot \SI{0.105}{\hpa}
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,\enskip
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\Delta z = \mState_{t-1}^{z} - \mState_{t}^z
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.
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\label{eq:baroTransition}
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\end{equation}
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Within the evaluation bla bla
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The evaluation following the transition then compares the predicted relative pressure with the observed one
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using a normal distribution with the previously estimated $\sigma_\text{baro}$:
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\begin{equation}
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xx
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p(\mObsVec_t \mid \mStateVec_t)_\text{baro} = \mathcal{N}(\mObs_t^{\mObsPressure} \mid \mState_t^{\mStatePressure}, \sigma_\text{baro}).
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\label{eq:baroEval}
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\end{equation}
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we use the system's setup time to not only determine the relative base but also for estimating the barometers
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uncertainty \sigma_\text{baro} used within the evaluation.
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\subsection{Wi-Fi \& iBeacons}
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For additional absolute location hints, we use the Smartphones Wi-Fi and iBeacon sensor to measure the signal-strengths
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@@ -40,7 +55,7 @@
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and calculate the resulting probability as described in \cite{ipin2015}:
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\begin{equation}
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\mProb(\mObsVec \mid \mStateVec)_\text{wifi} =
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\mProb(\mObsVec_t \mid \mStateVec_t)_\text{wifi} =
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\prod\limits_{i=1}^{n} \mathcal{N}(\mRssi_\text{wifi}^{i} \mid P_{r}(\mMdlDist_{i}, \Delta{f_{i}}), \sigma_{\text{wifi}}^2).
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\label{eq:wifiTotal}
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\end{equation}
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@@ -56,6 +71,9 @@
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Again, $\mPLE$ is determined emprically. \todo{faellt hier meist kleiner aus, weil ja kuerzere reichweite etc}
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\subsection{Step- \& Turn-Detection}
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To prevent degradation within the particle-filter \cite{??} due to downvoting of particles with increased
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