first draft introduction, as far is toni can write.
This commit is contained in:
@@ -1,54 +1,41 @@
|
||||
\section{Introduction}
|
||||
|
||||
Sensor fusion approaches are often based upon probabilistic descriptions like particle filters, using samples to represent the distribution of a dynamical system.
|
||||
To update the system recursively in time, probabilistic sensor models process the noise measurements and a state transition function provides the system's dynamics.
|
||||
To update the system recursively in time, probabilistic sensor models process the noisy measurements and a state transition function provides the system's dynamics.
|
||||
Therefore a sample or particle is a representation of one possible system state, e.g. the position of a pedestrian within a building.
|
||||
In most real world scenarios one is then interested in finding the most probable state within the state space, to provide the "best estimate" of the underlying problem.
|
||||
In the discrete manner of a sample representation this is often done by calculating a single value, also known as sample statistic, to serve as a "best guess".
|
||||
This values is often calculated by means of simple parametric point estimators, e.g. using weighted-average of all samples or that one sample with the highest overall weight \cite{}.
|
||||
In the discrete manner of a sample representation this is often done by providing a single value, also known as sample statistic, to serve as a "best guess".
|
||||
This value is then calculated by means of simple parametric point estimators, e.g. the weighted-average over all samples, the sample with the highest weight or by assuming other parametric statistics like normal distributions \cite{}.
|
||||
%da muss es doch noch andere methoden geben... verflixt und zugenäht... aber grundsätzlich ist ein weighted average doch ein point estimator? (https://www.statlect.com/fundamentals-of-statistics/point-estimation)
|
||||
%Für related work brauchen wir hier definitiv quellen. einige berechnen ja auch https://en.wikipedia.org/wiki/Sample_mean_and_covariance oder nehmen eine gewisse verteilung für die sample menge and und berechnen dort die parameter
|
||||
|
||||
%multimodalities...
|
||||
While such methods are computational fast and suitable most of the time, it is not uncommon that they fail to recover the state in more complex scenarios.
|
||||
Especially time-sequential, non-linear and non-Gaussian state spaces, depending upon a high number of different sensor types, frequently suffer from a multimodal representation of the posterior distribution.
|
||||
As a result, those techniques are not able to provide an accurate statement about the most probable state, rather causing misleading or false outcomes.
|
||||
For example in a localization scenario where a bimodal distribution represents the current posterior, a reliable position estimation is more likely to be at one of the modes, instead of somewhere in-between.
|
||||
Additionally, in most practical scenarios the sample size and therefore the resolution is limited, causing the variance of the sample based estimate to be high \cite{Verma2003}.
|
||||
|
||||
It is obvious, that a computation of the full posterior could solve the above, but finding such an analytical solution is an intractable problem, what is the reason for applying a sample representation in the first place.
|
||||
Another promising way is to recover the probability density function from the sample set itself, by using a non-parametric estimator like a kernel density estimation (KDE).
|
||||
With this, it is easy to find the "real" most probable state and thus to avoid the aforementioned drawbacks.
|
||||
However, non-parametric estimators tend to consume a large amount of computational time, which renders them unpractical for real time scenarios.
|
||||
Nevertheless, the availability of a fast processing density estimate might improve the accuracy of today's sensor fusion systems without sacrificing their real time capability.
|
||||
|
||||
\commentByToni{Der nachfolgende Satz ist ziemlich wichtig. Find ich aktuell noch nicht gut. Allgemein sollte ihr jetzt noch ca eine viertel Seite ein wenig die Methode grob beschrieben werden.
|
||||
The basic idea ...
|
||||
We formalize this ...
|
||||
Our experiments support our ..
|
||||
}
|
||||
|
||||
%interested in the most proper state within the state space of the dynamic system
|
||||
%echte antwort computationel complex deswegen %weighted-average -> problem multimodal; sample mit höhsten wert -> springt viel rum
|
||||
%-> Density -> KDE
|
||||
|
||||
%Egal auf welchem Weg das sample set entstanden ist, am ende muss ein verwertbarer wert rauskommen. irgendein
|
||||
|
||||
After calculating
|
||||
|
||||
|
||||
|
||||
In real world scenarios
|
||||
|
||||
|
||||
%find the state that describs our probleme the best
|
||||
%
|
||||
|
||||
% ... in many real world scenarios an estimate of the problem state is required e.g. the position of a pedestrian within a building...
|
||||
%this is often done by calculating the weighted-average of all samples or
|
||||
|
||||
%however multimodalities.
|
||||
|
||||
% in the optimal case
|
||||
|
||||
bessere entscheidung kde raus machen, als einfach nur
|
||||
|
||||
to receive this information
|
||||
|
||||
based upon a set of descrete samples
|
||||
|
||||
%for this purpose parameteric estimators like ... are often used in real time scenarios because of their low complexity and short computatinal time.
|
||||
|
||||
% however,
|
||||
non parameteric estimators like kde
|
||||
In this paper, a novel approximation approach for rapid computation of the KDE is presented.
|
||||
%Therefore, this paper presents a novel approximation approach for rapid computation of the KDE.
|
||||
%In this paper, a well known approximation of the Gaussian filter is used to speed up the computation of the KDE.
|
||||
|
||||
|
||||
|
||||
\cite{Deinzer01-CIV}
|
||||
|
||||
|
||||
|
||||
% KDE wellknown nonparametic estimation method
|
||||
% Flexibility is paid with slow speed
|
||||
% Finding optimal bandwidth
|
||||
|
||||
@@ -2880,3 +2880,14 @@ year = {2003}
|
||||
year={2017, submitted},
|
||||
}
|
||||
|
||||
@inproceedings{Verma2003,
|
||||
author = {Verma, Vandi and Thrun, Sebastian and Simmons, Reid},
|
||||
doi = {10.1.1.68.4380},
|
||||
booktitle={Proc. of the International Joint Conference on Artificial Intelligence (IJCAI)},
|
||||
pages = {976--984},
|
||||
title = {{Variable resolution particle filter}},
|
||||
year = {2003}
|
||||
}
|
||||
|
||||
|
||||
|
||||
|
||||
Reference in New Issue
Block a user