Range-only measurements based target following for wheeled mobile robots

We consider the problem of navigation and guidance of a wheeled mobile robot towards a maneuvering target based on the measurements concerning only the distance from the robot to the target. We propose a sliding mode controller that drives the robot to the predefined distance from the target and makes the robot follow the target at this distance. Mathematically rigorous proof of convergence and stability of the proposed guidance law is presented. Simulation results confirm the applicability and performance of the proposed guidance approach.     

Equiangular navigation and guidance of a wheeled mobile robot based on range-only measurements

We consider the problems of a wheeled mobile robot navigation and guidance towards an unknown stationary or maneuvering target using range-only measurements. We propose and study several methods for navigation and guidance termed Equiangular Navigation Guidance (ENG) laws. We give mathematically rigorous analysis of the proposed guidance laws. The performance is confirmed with computer simulations and experiments with ActivMedia Pioneer 3-DX wheeled robots.     

Design of a 3D snapshot based visual flight control system using a single camera in hover

The problem of developing a reliable system for sensing and controlling the hover of a Micro Air Vehicle (MAV) using visual snapshots is considered. The current problem is part of a larger project, which is developing an autonomous MAV, controlled by vision only information. A new algorithm is proposed that uses a stored image of the ground, a snapshot taken of the ground directly under the MAV, as a visual anchor point. The absolute translation of the aircraft and its velocity are then calculated by comparing the subsequent frames with the stored image and fed into the position controller. In order to increase the performance, several issues, such as effects of scale uncertainty on the closed loop stability of the platform are investigated. For controller design and testing purposes, we analytically derive a complete model of a small size helicopter with no stabilizing bar (flybar). The simulation results for 2D and 3D snapshots confirm the effectiveness of the proposed algorithm.     

Method for tracking of environmental level sets by a unicycle-like vehicle

We consider a single Dubins-like vehicle traveling with a constant longitudinal speed in a planar region supporting an unknown field distribution. A sensor provides the distribution value at the vehicle location. We present a new sliding mode control method for tracking environmental level sets: the vehicle is steered to the set where the distribution assumes a pre-specified value and circulates along this set afterwards. The proposed control algorithm does not employ gradient estimation and is non-demanding with respect to both computation and motion. Its mathematically rigorous justification is provided. The effectiveness of the proposed guidance law is confirmed by computer simulations.     

Fe2O3/TiO2/Activated Carbon Nanocomposite with Synergistic Effect of Adsorption and Photocatalysis

Fe₂O₃/TiO₂/activated carbon (FT/AC) nanocomposites supported on silica gel beads were synthesized using a sonochemical method and fully characterized. The response surface method was applied to optimize the removal of Pb(II) ions by nanocomposites under visible light. The experiments were conducted by adjusting three parameters, i.e., initial concentration of Pb(II) ions, dosage of Fe₂O₃/TiO₂ (FT) photocatalyst, and pH. The FT/AC nanocomposite showed higher efficiency for Pb(II) ion removal in comparison with FT due to the synergistic effect of activated carbon combined with Fe₂O₃/TiO₂.     

Unsupervised help-trained LS-SVR-based segmentation in speaker diarization system

Multimedia Tools and Applications - In this paper, we propose a new segmentation method for diarization applications. In the proposed method, segmentation is performed using a discriminatively...     

A method for guidance and control of an autonomous vehicle in problems of border patrolling and obstacle avoidance

We present a sliding mode based method for a unicycle-like vehicle control and guidance. The proposed guidance-control law is applied to the problems of border patrolling and obstacle avoidance. A mathematically rigorous analysis of this law is provided.     

Effective Permeability Calculation Using Boundary Element Method in Naturally Fractured Reservoirs

A model is presented to calculate the effective permeability tensor in naturally fractured reservoirs using Boundary Element Methods (BEM). Arbitrary fractures of different scales based on their length are considered. Interface boundary condition is used to model the short fractures as an enhancement of matrix permeability. Long fractures, on the other hand are treated as source/sink in the corresponding blocks. Periodic boundary condition is applied to the grid-block boundaries to calculate the elements of effective permeability tensor. Darcy's law and Navier-stoke's equation are applied to fluid flow in rock matrix and fractures, respectively. An important feature of this approach is that the fluid flow in matrix-fracture interface is coupled by Poisson's equation and fluid flow in the rest of the matrix is formulated by Laplace's equation. This paper also presents an innovative approach to optimization and parallelization of the model by High Performance Computing (HPC) techniques. The model has been validated against analytical results and applied to a typical case where arbitrary fractures of different sizes are assumed within the grid blocks. The effective block permeability tensors can be implemented into a reservoir simulator to calculate fluid flow through the naturally fractured reservoirs.     

Navigation of a unicycle-like mobile robot for environmental extremum seeking

We consider a single Dubins-like mobile robot traveling with a constant longitudinal speed in a planar region supporting an unknown field distribution. A single sensor provides the distribution value at the current robot location. We present a new sliding mode navigation strategy that drives the robot to the location where the field distribution attains its maximum. The proposed control algorithm does not employ gradient estimation and is non-demanding with respect to both computation and motion. Its mathematically rigorous analysis and justification are provided. Simulation results confirm the applicability and performance of the proposed guidance approach.