G. INDIVERI

The issue of designing smooth planar paths with maximum curvature and curvature derivative constraints is addressed. The proposed solution can be used to build C^infty class reference paths for marine vehicles linking a set of via points while guaranteeing bounded curvature and curvature derivative.

The use of mono-directional thrusters on under- water vehicle poses interesting issues on actuator allocation, fault detection and accommodation. Preliminary results relative to the horizontal motion of an unhabited underwater vehicle (UUV) are presented.

A nonlinear control law to steer the unicycle model to a static or dynamic target pose is presented. If the target is static the control signals are smooth in their arguments and the solution guarantees exponential convergence of the distance and orientation errors to zero. The major advantages of the proposed approach are that there is no need...

This reports describes the basic ideas behind a novel parameter identification algorithm exhibiting high robustness with respect to outlying data. The algorithm consists in minimizing an entropy-like cost function of the identification residuals. Robustness to outliers is obtained as a consequence of the fact that the used cost function rewards...

Swedish wheeled robots have received growing attention over the last few years. Their kinematic models have interesting properties in terms of mobility and possible singularities. This paper addresses the issue of kinematic modeling, singularity analysis, and motion control for a generic vehicle equipped with N Swedish wheels.

A closed loop, time-invariant and globally stable control law for a bicycle-like kinematic model is proposed. The resulting paths are smooth and the curvature bounded on the whole state space trajectories. As linear velocity can be kept arbitrary small, thus avoiding large lateral accelerations and actuator saturation problems, it is suggested...

Calculating smooth tra jectories of bounded curvature has received a very wide attention in the robotic literature of the last 40 years. Most results focus on the study of wheeled non-holonomic vehicles and are concerned with 2D path generation algorithms. The problem of smooth and least curvature 3D path planning is addressed with a...

In this paper, the feedback control of a nonholonomic 3D vehicle is considered; namely, the problem of steering an underactuated rigid body to a target position along a desired direction is addressed. A simple time-invariant strategy is determined on the basis of standard vector kinematics and a Lyapunov-like stability analysis. The resulting...

A novel strategy to design time invariant motion controllers for underactuated mobile systems is applied to the position and attitude control of an underactuated 3D vehicle. The idea consists in defining a velocity vector field such that an ideal, fully actuated system would exponentially achieve the control objective by simply following such...

A lumped parameter model of open-frame unmanned underwater vehicles (UUV's) including the effects of propeller-hull and propeller-propeller interactions is presented. The identification of the model parameters consists of a least squares method using only on-board sensor data without requiring any towing tank tests. The identification scheme is...

The objective of the low level control system of marine vehicles is to generate a desired thrust in the face of environmental disturbances and modelling uncertainties. The control objective of standard low level control solutions is the propeller angular speed that is assumed to be related to the produced thrust through a known hydrodynamic...

Swedish wheeled mobile robots have remarkable mobility properties allowing them to rotate and translate at the same time. Being holonomic systems, their kinematics model results in the possibility of designing separate and independent position and heading trajectory tracking control laws. Nevertheless, if these control laws should be...