Authors:
Robert Mahony,
Tarek Hamel,
Volume: 1, Page 2971 Paper number 1760
Abstract:
A number of recent papers have considered trajectory tracking control
design for unmanned aerial vehicles (UAVs). One method to obtain an
integrated non-linear control for such vehicles is to exploit the underlying
cascade structure (input/output linearizability) of the systems. The
dynamics of these vehicles have a particular form when expressed in
an inertial frame of reference that lends itself to this approach.
In practice, an autonomous vehicle has access only to absolute measurements
of non-inertial variables such as linear acceleration and angular velocity
along with local measurements of inertial quantities such as position,
velocity and orientation. Expressing the dynamics of a typical system
in body fixed frame coordinates introduces dynamic coupling that appears
to destroy the simple structure of the inertial equations. In this
paper it is shown that the inherent passivity-like properties of the
underlying mechanical system may be exploited to obtain Lyapunov control
design for the more general system equations expressed in the body
fixed frame of an unmanned aerial vehicle. This avoids a possibly
difficult and highly non-robust state reconstruction that would be
necessary before existing control designs could be applied.
Authors:
Pedro Encarnação,
António M. Pascoal,
Volume: 1, Page 2977 Paper number 1837
Abstract:
A new methodology is proposed for the design of path following systems
for autonomous underwater vehicles. Global convergence to reference
paths is achieved with a nonlinear control strategy that takes explicitly
into account the dynamics of the vehicle. Formal convergence proofs
are indicated. Simulation results with the model of a prototype autonomous
underwater vehicle are presented to illustrate the performance of the
path following system derived.
Authors:
Giorgio Bartolini,
Mauro Coccoli,
Elisabetta Punta,
Volume: 1, Page 2983 Paper number 1614
Abstract:
This paper deals with the application of the sliding mode control theory
to the specific case of a manipulator for which mono-directional control
actions only have to be considered. In particular the control of an
underwater gripper is presented. Many even complex robotic structures,
can be actuated by mono-directional control actions, for example the
so called tendon-arms, the jet-actuated vehicles, underwater vehicles
with mono-directional thrusters, etc.. The robotic system which is
considered in the paper belongs to the above class, since it is actuated
by voice coil motors which, acting on a hydraulic circuit, are able
to generate mono--directional forces. In practical realizations actuators
often show imprecise relationships between the electrical input signals
and the mechanical outputs, that is joint forces or torques. Such a
situation constitutes a source of uncertainties we have to deal with.
A sliding mode control methodology based on the use of a simplex of
constant control vectors is presented, which has revealed to be general
enough to work with different applications too.
Authors:
Pascal Morin,
Claude Samson,
Volume: 1, Page 2989 Paper number 1626
Abstract:
A characterization of the Lie Algebra Rank Condition by transverse
periodic functions is applied to feedback stabilization of a class
of nonlinear systems. The approach is illustrated on controllable homogeneous
driftless systems subjected to known additive perturbations. A generalized
path tracking problem for mobile robots is then addressed, in connection
with some aspects of the path planning problem.
Authors:
António Pedro Aguiar,
Ahmad N. Atassi,
António M. Pascoal,
Volume: 1, Page 2995 Paper number 1894
Abstract:
This paper addresses the problem of regulating the dynamic model of
a nonholonomic wheeled robot of the unicycle type to a point with a
desired orientation. A simple controller is derived that yields global
convergence of the trajectories of the closed loop system in the presence
of parametric modeling uncertainty. Controller design relies on a non
smooth coordinate transformation in the original state space, followed
by the derivation of a Lyapunov-based, adaptive, smooth control law
in the new coordinates. Convergence to the origin is analyzed and simulation
results are presented.
Authors:
Petter Ögren,
Lars Petersson,
Magnus Egerstedt,
Xiaoming Hu,
Volume: 1, Page 3001 Paper number 1858
Abstract:
A solution to the trajectory tracking problem for mobile manipulators
is proposed and implemented on a real robotic system. Given a trajectory
for the gripper to follow, a tracking algorithm for the manipulator
is designed, and at the same time the base motions are generated in
such a way that the base is coordinated with the gripper while reactively
avoiding obstacles. Furthermore, it is shown that the method allows
arbitrary upper and lower bounds on the gripper-base distance to be
set, and this can be achieved without introducing deadlocks into the
system.
Authors:
Guangyan Xu,
Danwei Wang,
Keliang Zhou,
Volume: 1, Page 3007 Paper number 1168
Abstract:
This paper proposes a robust trajectory tracking control scheme for
a nonholonomic wheeled mobile robot. This control scheme achieves full
state tracking in the sense of uniform ultimate boundedness. It is
robust against the uncertain inertia parameters, unknown disturbances
and initial errors.
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