6,001 research outputs found
Suspended Load Path Tracking Control Using a Tilt-rotor UAV Based on Zonotopic State Estimation
This work addresses the problem of path tracking control of a suspended load
using a tilt-rotor UAV. The main challenge in controlling this kind of system
arises from the dynamic behavior imposed by the load, which is usually coupled
to the UAV by means of a rope, adding unactuated degrees of freedom to the
whole system. Furthermore, to perform the load transportation it is often
needed the knowledge of the load position to accomplish the task. Since
available sensors are commonly embedded in the mobile platform, information on
the load position may not be directly available. To solve this problem in this
work, initially, the kinematics of the multi-body mechanical system are
formulated from the load's perspective, from which a detailed dynamic model is
derived using the Euler-Lagrange approach, yielding a highly coupled, nonlinear
state-space representation of the system, affine in the inputs, with the load's
position and orientation directly represented by state variables. A zonotopic
state estimator is proposed to solve the problem of estimating the load
position and orientation, which is formulated based on sensors located at the
aircraft, with different sampling times, and unknown-but-bounded measurement
noise. To solve the path tracking problem, a discrete-time mixed
controller with pole-placement constraints
is designed with guaranteed time-response properties and robust to unmodeled
dynamics, parametric uncertainties, and external disturbances. Results from
numerical experiments, performed in a platform based on the Gazebo simulator
and on a Computer Aided Design (CAD) model of the system, are presented to
corroborate the performance of the zonotopic state estimator along with the
designed controller
PRIORITIES IN COST SHARING FOR SOIL AND WATER CONSERVATION: A REVEALED PREFERENCE STUDY
Resource /Energy Economics and Policy,
Gas rotation, shocks and outflow within the inner 3 kpc of the radio galaxy 3C 33
We present optical integral field spectroscopy obtained with the Gemini
Multi-Object Spectrograph of the inner kpc of the
narrow line radio galaxy 3C 33 at a spatial resolution of 0.58 kpc. The gas
emission shows three brightest structures: a strong knot of nuclear emission
and two other knots at kpc south-west and north-east of the
nucleus along the ionization axis. We detect two kinematic components in the
emission lines profiles, with a "broader component" (with velocity dispersion
km s) being dominant within a 1 kpc wide strip
("the nuclear strip") running from the south-east to the north-west,
perpendicular to the radio jet, and a narrower component ( km
s) dominating elsewhere. Centroid velocity maps reveal a rotation
pattern with velocity amplitudes reaching km s in the
region dominated by the narrow component, while residual blueshifts and
redshifts relative to rotation are observed in the nuclear strip, where we also
observe the highest values of the [N II]/H{\alpha}, [S II]/H{\alpha} and [O
I]/H{\alpha} line ratios, and an increase of the gas temperature (
K), velocity dispersion and electron density ( cm). We
interpret these residuals and increased line ratios as due to a lateral
expansion of the ambient gas in the nuclear strip due to shocks produced by the
passage of the radio jet. The effect of this expansion in the surrounding
medium is very small, as its estimated kinetic power represents only of the AGN bolometric luminosity. A possible signature of
inflow is revealed by an increase in the [O I]/H{\alpha} ratio values and
velocity dispersions in the shape of two spiral arms extending to 2.3 kpc
north-east and south-west from the nucleus.Comment: 16 pages, 14 figures, accepted by MNRA
- …