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Autonomous landing of quad rotor UAV on a maritime vessel is a challenging task, as low cost sensors, unknown movements of the landing surface, and external disturbances make it difficult to generate a relative pose estimate with sufficient accuracy for landing. In this work, we propose an architecture that avoids sensor limitations while allowing for accurate relative pose estimation, even in the...
The tailsitter aircraft merges the endurance and speed of fixed-wing aircraft with the flexibility and VTOL abilities of rotorcraft. Because of the requirement to be functional at a full range of attitudes, quaternions are typically employed to calculate attitude error. Attitude control is then accomplished by using the vector component of the error quaternion to drive flight control surfaces. This...
This paper presents a 100 Hz monocular position based visual servoing system to control a quadrotor flying in close proximity to vertical structures approximating a narrow, locally linear shape. Assuming the object boundaries are represented by parallel vertical lines in the image, detection and tracking is achieved using Plücker line representation and a line tracker. The visual information is fused...
The paper studies the problem of finite time formation control for multiple vehicles. The vehicle is modeled as the full actuated rigid body, both the formation time and the geometric structure of the formation are specified by the task. An open optimal control law is derived by using Pontryagins minimum principle, and is converted to the closed form by feeding the current state back under the assumption...
This paper proposes a new approach to the boundary value problem of finding a vehicle path from an initial state, defined by a position and velocity vector, to a target position. The presented method explicitly considers magnitude constraints on both the velocity and the acceleration of the vehicle when determining the path. A semi-analytic and computationally efficient algorithm is employed, applicable...
Road traffic accident is one of the major causes of death in Bangladesh. In this article, we propose a method that uses road side video data to learn the traffic pattern and uses vision based techniques to track and determine various kinetic features of vehicles. Finally, the proposed method detects anomaly (possibility of accident) and accidents on the road. The proposed method shows approximately...
In this article an adaptive controller is developed in order to estimate the inertia tensor, the mass and the wind parameters (considering wind as a parameter in the input) for the underactuated quad-rotor mini-aircraft. Experimental tests are performed in an educational platform. The proposed control scheme uses the parameter estimation issued from gradient type algorithm. Finally simulations and...
We investigate methods to improve fault-tolerance of Autonomous Underwater Vehicles (AUVs) to increase their reliability and persistent autonomy. We propose a learning-based approach that is able to discover new control policies to overcome thruster failures as they happen. The proposed approach is a model-based direct policy search that learns on an on-board simulated model of the AUV. The model...
This paper presents a novel Vision-based Nonlinear Model Predictive Control (NMPC) scheme for an under-actuated underwater robotic vehicle. In this scheme, the control loop does not close periodically, but instead a self-triggering framework decides when to provide the next control update. Between two consecutive triggering instants, the control sequence computed by the NMPC is applied to the system...
In this paper, we tackle the problem of trajectory tracking for a particular class of underactuated vehicles with full torque actuation and a single force direction (thrust) that is fixed relative to a body attached frame. Additionally, we consider that thrust reversal is not available. We present the design of a hybrid controller that, under some given assumptions, is able to globally asymptotically...
This paper presents an on-line three dimensional trajectory planner for an unmanned vehicle following a Leader vehicle, where the Follower remains at a specified relative position with respect to the Leader. The planner defines the trajectory for a virtual vehicle that will be used as reference for the real Follower vehicle. The virtual Follower behaves like a three dimensional trailer attached to...
A stabilization and control technique developed for steering swarms of unmanned micro aerial vehicles is proposed in this paper. The presented approach based on a visual relative localization of swarm particles is designed for utilization of multi-robot teams in real-world dynamic environments. The core of the swarming behaviour is inspired by Reynold's BOID model proposed for 2D simulations of schooling...
This paper considers the problem of directing a family of underactuated ships to formation tracking a set of closed orbits and achieve attitude synchronization. It shows that our previous concentric compression design is useful to the coordinated motion of underactuated ships. The condition that the total linear speed of each ship is greater than zero is ensured by introducing a potential function...
We propose a method capable of acquiring an occupancy grid map-based representation of the local, static driving environment around an intelligent vehicle in the presence of dynamic objects. These corrupt the representation due to violating the underlying static-world assumptions of common grid mapping algorithms and are therefore detected and filtered from the map. For this purpose, a subsequent...
Changing lane is one of the methods to reach the destination faster and also could bring more highway traffic accidents. This study through the traffic feature recognition, cluster analysis, similarity measurements and estimation, analyzed the vehicle operation parameter before changing lane, proposed a changing lane probability estimating model which combines the SOM (Self-Organization Map) and BP...
The goal of this paper is the analysis of cryptographic mechanisms utilised in VANET communication for Intelligent Transportation Systems with focus on security. The practical part of the contribution is dedicated to modelling of security properties of VANET networks in OPNET Modeler modelling tool extended by the implementation of the OpenSSL library. The designed models simulate a transmission of...
This paper is concerned with the design of an observer-based fault detection module for nonlinear rail vehicle suspension systems with the method of restructuring states and faults which can affect the system performance. An alarm signal will be sent by the designed observer if the residual evaluation is larger than a prescribed threshold when there are detectable actuator and sensor faults. The track...
The technology of vehicle video detecting and tracking has been playing an important role in the ITS (Intelligent Transportation Systems) field during recent years. The occlusion phenomenon among vehicles is one of the most difficult problems related to vehicle tracking. In order to handle occlusion, this paper proposes an effective solution that applied Markov Random Field (MRF) to the traffic images...
This paper presents a novel method on the motion and path planning for unicycle robots in environments with static circular obstacles. The method employs a family of 2-dimensional analytic vector fields, which have singular points of high-order type and whose integral curves exhibit various patterns depending on the value of a parameter λ. More specifically, for a known value of λ the vector field...
An estimator of external generalized forces (force plus moments) acting on aerial platforms, and based on the momentum of the mechanical system, is proposed for the control of VToL UAVs together with a hierarchical architecture separating the translational and rotational dynamics of the vehicle. The closed-loop system equations are shaped as mechanical impedances, programmable through the controller...
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