176,471 research outputs found
Linear estimation in Krein spaces. Part II. Applications
We have shown that several interesting problems in Hâ-filtering, quadratic game theory, and risk sensitive control and estimation follow as special cases of the Krein-space linear estimation theory developed in Part I. We show that all these problems can be cast into the problem of calculating the stationary point of certain second-order forms, and that by considering the appropriate state space models and error Gramians, we can use the Krein-space estimation theory to calculate the stationary points and study their properties. The approach discussed here allows for interesting generalizations, such as finite memory adaptive filtering with varying sliding patterns
Near-Optimal Sensor Scheduling for Batch State Estimation: Complexity, Algorithms, and Limits
In this paper, we focus on batch state estimation for linear systems. This
problem is important in applications such as environmental field estimation,
robotic navigation, and target tracking. Its difficulty lies on that limited
operational resources among the sensors, e.g., shared communication bandwidth
or battery power, constrain the number of sensors that can be active at each
measurement step. As a result, sensor scheduling algorithms must be employed.
Notwithstanding, current sensor scheduling algorithms for batch state
estimation scale poorly with the system size and the time horizon. In addition,
current sensor scheduling algorithms for Kalman filtering, although they scale
better, provide no performance guarantees or approximation bounds for the
minimization of the batch state estimation error. In this paper, one of our
main contributions is to provide an algorithm that enjoys both the estimation
accuracy of the batch state scheduling algorithms and the low time complexity
of the Kalman filtering scheduling algorithms. In particular: 1) our algorithm
is near-optimal: it achieves a solution up to a multiplicative factor 1/2 from
the optimal solution, and this factor is close to the best approximation factor
1/e one can achieve in polynomial time for this problem; 2) our algorithm has
(polynomial) time complexity that is not only lower than that of the current
algorithms for batch state estimation; it is also lower than, or similar to,
that of the current algorithms for Kalman filtering. We achieve these results
by proving two properties for our batch state estimation error metric, which
quantifies the square error of the minimum variance linear estimator of the
batch state vector: a) it is supermodular in the choice of the sensors; b) it
has a sparsity pattern (it involves matrices that are block tri-diagonal) that
facilitates its evaluation at each sensor set.Comment: Correction of typos in proof
Theoretical optimal modulation frequencies for scattering parameter estimation and ballistic photon filtering in diffusive media
The efficiency of using intensity modulated light for estimation of
scattering properties of a turbid medium and for ballistic photon
discrimination is theoretically quantified in this article. Using the diffusion
model for modulated photon transport and considering a noisy quadrature
demodulation scheme, the minimum-variance bounds on estimation of parameters of
interest are analytically derived and analyzed. The existence of a
variance-minimizing optimal modulation frequency is shown and its evolution
with the properties of the intervening medium is derived and studied.
Furthermore, a metric is defined to quantify the efficiency of ballistic photon
filtering which may be sought when imaging through turbid media. The analytical
derivation of this metric shows that the minimum modulation frequency required
to attain significant ballistic discrimination depends only on the reduced
scattering coefficient of the medium in a linear fashion for a highly
scattering medium
Discrete spherical means of directional derivatives and Veronese maps
We describe and study geometric properties of discrete circular and spherical
means of directional derivatives of functions, as well as discrete
approximations of higher order differential operators. For an arbitrary
dimension we present a general construction for obtaining discrete spherical
means of directional derivatives. The construction is based on using the
Minkowski's existence theorem and Veronese maps. Approximating the directional
derivatives by appropriate finite differences allows one to obtain finite
difference operators with good rotation invariance properties. In particular,
we use discrete circular and spherical means to derive discrete approximations
of various linear and nonlinear first- and second-order differential operators,
including discrete Laplacians. A practical potential of our approach is
demonstrated by considering applications to nonlinear filtering of digital
images and surface curvature estimation
MIMO PID Controller Tuning Method for Quadrotor Based on LQR/LQG Theory
In this work, a new pre-tuning multivariable PID (Proportional Integral Derivative)
controllers method for quadrotors is put forward. A procedure based on LQR/LQG (Linear Quadratic
Regulator/Gaussian) theory is proposed for attitude and altitude control, which suposes a considerable
simplification of the design problem due to only one pretuning parameter being used. With the aim to
analyze the performance and robustness of the proposed method, a non-linear mathematical model of
the DJI-F450 quadrotor is employed, where rotors dynamics, together with sensors drift/bias properties
and noise characteristics of low-cost commercial sensors typically used in this type of applications are
considered. In order to estimate the state vector and compensate bias/drift effects in the measures,
a combination of filtering and data fusion algorithms (Kalman filter and Madgwick algorithm for attitude
estimation) are proposed and implemented. Performance and robustness analysis of the control system
is carried out by employing numerical simulations, which take into account the presence of uncertainty
in the plant model and external disturbances. The obtained results show the proposed controller design
method for multivariable PID controller is robust with respect to: (a) parametric uncertainty in the plant
model, (b) disturbances acting at the plant input, (c) sensors measurement and estimation errors
JOINT ESTIMATION OF STATES AND PARAMETERS OF LINEAR SYSTEMS WITH PARAMETER FAULTS UNDER NON-GAUSSIAN NOISES
Joint estimation of states and time-varying parameters of linear state space models is of practical importance for the fault diagnosis and fault tolerant control. Previous works on this topic consider the joint estimation in the Gaussian noise environment, but not in the presence of outliers. The known fact is that the measurements have inconsistent observations with the largest part of the observation population (outliers). They can significantly make worse the properties of linearly recursive algorithms which are designed to work in the presence of Gaussian noises. This paper proposes the strategy of the joint parameter-state robust estimation of linear state space models in the presence of non-Gaussian noises. The case of parameter-dependent matrices is considered. Because of its good features in robust filtering, the extended Masreliez-Martin filter represents a cornerstone for realization of the robust algorithms for joint state-parameter estimation of linear time-varying stochastic systems in the presence of non-Gaussian noises. The good features of the proposed robust algorithm for joint estimation of linear time-varying stochastic systems are illustrated by intensive simulations
- âŠ