3,671 research outputs found
Velocity-aided Attitude Estimation for Accelerated Rigid Bodies
Two nonlinear observers for velocity-aided attitude estimation, relying on
gyrometers, accelerometers, magnetometers, and velocity measured in the
body-fixed frame, are proposed. As opposed to state-of-the-art body-fixed
velocity-aided attitude observers endowed with local properties, both observers
are (almost) globally asymptotically stable, with very simple and flexible
tuning. Moreover, the roll and pitch estimates are globally decoupled from
magnetometer measurements
Gradient-like observer design on the Special Euclidean group SE(3) with system outputs on the real projective space
A nonlinear observer on the Special Euclidean group for full
pose estimation, that takes the system outputs on the real projective space
directly as inputs, is proposed. The observer derivation is based on a recent
advanced theory on nonlinear observer design. A key advantage with respect to
existing pose observers on is that we can now incorporate in a
unique observer different types of measurements such as vectorial measurements
of known inertial vectors and position measurements of known feature points.
The proposed observer is extended allowing for the compensation of unknown
constant bias present in the velocity measurements. Rigorous stability analyses
are equally provided. Excellent performance of the proposed observers are shown
by means of simulations
Non-linear Symmetry-preserving Observer on Lie Groups
In this paper we give a geometrical framework for the design of observers on
finite-dimensional Lie groups for systems which possess some specific
symmetries. The design and the error (between true and estimated state)
equation are explicit and intrinsic. We consider also a particular case:
left-invariant systems on Lie groups with right equivariant output. The theory
yields a class of observers such that error equation is autonomous. The
observers converge locally around any trajectory, and the global behavior is
independent from the trajectory, which reminds of the linear stationary case.Comment: 12 pages. Submitted. Preliminary version publicated in french in the
CIFA proceedings and IFAC0
Rigid Body Attitude Estimation: An Overview and Comparative Study
The attitude estimation of rigid body systems has attracted the attention of many researchers over the years. The development of efficient estimation algorithms that can accurately estimate the orientation of a rigid body is a crucial step towards a reliable implementation of control schemes for underwater and flying vehicles.
The primary focus of this thesis consists in investigating various attitude estimation techniques and their applications.
Two major classes are discussed. The first class consists of the earliest static attitude determination techniques relying solely on a set of body vector measurements of known vectors in the inertial frame. The second class consists of dynamic attitude estimation and filtering techniques, relying on body vector measurements as well other measurements, and using the dynamical equations of the system under consideration.
Various attitude estimation algorithms, including the latest nonlinear attitude observers, are presented and discussed, providing a survey that covers the evolution and structural differences of these estimation methods.
Simulation results have been carried out for a selected number of such attitude estimators. Their performance in the presence of noisy measurements, as well as their advantages and disadvantages are discussed
Constructive Equivariant Observer Design for Inertial Velocity-Aided Attitude
Inertial Velocity-Aided Attitude (VAA) is an important problem in the control
of Remotely Piloted Aerial Systems (RPAS), and involves estimating the velocity
and attitude of a vehicle using gyroscope, accelerometer, and inertial-frame
velocity (e.g. GPS velocity) measurements. Existing solutions tend to be
complex and provide limited stability guarantees, relying on either high gain
designs or assuming constant acceleration of the vehicle. This paper proposes a
novel observer for inertial VAA that exploits Lie group symmetries of the
system dynamics, and shows that the observer is synchronous with the system
trajectories. This is achieved by adding a virtual state of only three
dimensions, in contrast to the larger virtual states typically used in the
literature. The error dynamics of the observer are shown to be almost globally
asymptotically and locally exponentially stable. Finally, the observer is
verified in simulation, where it is shown that the estimation error converges
to zero even with an extremely poor initial condition.Comment: 11 pages, 2 figures, submitted to NOLCOS 202
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