The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
The use of the Bluetooth smart technology as a communication framework to interconnect the robots is presented in this paper. Moreover, signal metrics of this network are used to provide an embedded Range Only localization scheme (RO-SLAM). When working with teams of robots, the communication between them is very important as it allows them to cooperate for the performing of the tasks. Additionally,...
This paper considers the disturbance observer- based distributed fault-tolerant containment control problem for longitudinal motion of multiple unmanned aerial vehicles (multi-UAVs) in the presence of actuator, sensor faults, and input saturation when only a subset of the multi-UAVs has access to the leaders. The communication network is an undirected, fixed topology and the distributed control scheme...
This paper presents two approaches considering a distributed framework for joint optimization of sensor coverage for target detection and target tracking for maximizing estimation performance for multi-agent systems. The first algorithm is based on the Lloyd algorithm, which uses a centroid of Voronoi partitions, one of the workarounds of sensor coverage problems. The other algorithm is based on the...
The inspection of bridges and other infrastructure with UAVs when the sensors need to be in contact with the surface (i.e. ultrasound for crack inspection or reflector prism for beam deflection) is a great challenge due to the coupling which occurs between the aerial and the inspection problems. This paper presents a new design of a multirotor UAV that can be used in some of these applications to...
This paper presents a combined perception systems and planning algorithms approach to the problem of autonomous aerial robotic navigation and exploration in degraded visual (dark) GPS-denied environments. A perception system that comprises of a synchronized near-infrared stereo camera system, flashing LEDs, inertial sensors and a 3D depth sensor is utilized in order to derive visual-inertial odometry...
This paper proposes a guidance algorithm of a UAV for multiple targets tracking, considering physical constraints of the platform and its sensor. The on-board sensor used for target tracking is a camera. To relax the need of a gimbal system and provide flexibility in utilisation of the vision sensor, a new rotorcraft type of UAV is developed. The main focus in designing tracking guidance is to develop...
This paper presents a novel application of Recursive Fast Orthogonal Search (R-FOS) to develop a time- varying, linear, state-space model approximating the dynamics of a quadcopter. The algorithm is successfully executed in real-time at a rate of 1000Hz using a simulated quadcopter testbed. The performance of the linear models is evaluated in terms of Accumulated Mean Squared error (AMSE) over finite...
Multi-agent pursuit-evasion games are a common way to describe problems in topics like police missions, surveillance, or warfare. Since many agents are involved in such problems, a game-theoretical solution seems reasonable. Game-theoretical solution approaches are generally very complex, especially in games with more than two agents, as it is the case in this paper. More and more unmanned aerial...
This paper describes the 4-Dimensional Trajectory (4DT) optimisation algorithm implemented to avoid a variety Global Navigation Satellite System (GNSS) signal degradations predicted by Avionics Based Integrity Augmentation system (ABIA). The paper focusses on descent and initial curved GNSS approach phases in a dense Terminal Manoeuvring Area (TMA) scenario, with multiple aircraft converging on the...
Autonomous navigation and obstacle avoidance in complex terrains such as canyons or urban/indoor environments is one of the biggest challenges for the next generation of unmanned aircraft systems. Insects such as honeybees use optical flow for various navigation tasks. Similar strategies can be used by unmanned aircraft as well. More importantly, optical flow can be combined with inertial measurements...
Visual-inertial odometry (VIO) is a nonlinear estimation problem where control inputs, such as acceleration and angular velocity, play a significant role in the estimation performance. In this paper, we examine effects of controls on the VIO problem. We first analyze the effects of acceleration and angular velocity inputs on state observability of the VIO problem. Representing the vehicle dynamics...
Estimation of an Unmannaed Aerial Vehicle's (UAV) state, i.e., its pose and velocity, is fundamentally important to its operation. Computer vision provides an alternate or augmentation source for performing state estimation. This work uses an existing monocular Visual Simultaneous Localization and Mapping (VSLAM) system which estimates scaled vehicle position. Two observers are proposed for Visual...
A comparison of attitude estimation algorithms is performed to allow selection of an appropriate algorithm for a quadrotor collision recovery system. A Multiplicative Extended Kalman Filter (MEKF), an Unscented Kalman Filter (UKF), a complementary filter, an H∞ Filter, and adaptive varieties of the selected filters are chosen for comparison. The adaptive modifications to the estimation algorithms...
We treat the problem of collaborative multi- vehicle localization using time-varying range and relative velocity measurements. The proposed solution combines local nonlinear observers that estimate the relative positions between agents and their neighbors, and cooperative filters that fuse each agent's local estimates to globally localize them with respect to a target (and therefore to each other)...
In this work, we demonstrate that the position tracking performance of a quadrotor may be significantly improved for forward and vertical flight by incorporating simple lumped parameter models for induced drag and thrust, respectively, into the quadrotor dynamics and modifying the controller to compensate for these terms. We further show that the parameters for these models may be easily and accurately...
The tilting trirotor presented in this paper is able to perform levelled flight at almost null attitude which is an important requirement for fixed wing tilt rotors in view of the lift control during transition from hovering to forward flight. The nonlinear dynamics, the large effect of wind due to the small scale, and the absence of aerodynamic data at low speed and Reynolds numbers, are crucial...
This paper presents a novel autonomous take-off and landing approach which uses a discrete-time finite-horizon suboptimal nonlinear control strategy to achieve a smooth landing on specific colored platform. By color-based tracking we can improve the performance of the position landing by correcting the position given by the GPS. The signal of the GPS is not always reliable since the accuracy strongly...
The objective of this paper is to demonstrate the application of optimal control for generating dynamically constrained minimal time trajectories in micro unmanned airships. By design, airships are generally underactuated and underpowered limiting their maneuvering capabilities. Using a simplified dynamic model derived with experimentally derived coefficients, two trajectory planning simulations are...
Current state-of-the-art vision-based sense and avoid systems based on morphological and hidden Markov model filtering require the manual selection of static (timeinvariant) detection thresholds. Manually selecting suitable static detection thresholds is challenging (and currently requires highly trained operators) because it involves balancing tradeoffs between detection and false alarm performance...
The aim of this study is to investigate methods for computing the position of an intruder aircraft relative to an observer aircraft with onboard stereo cameras. To focus on relative position estimation rather than the intruder aircraft detection through image processing, the first phase is to generate camera images given the relative position information. This process uses a simple pinhole camera...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.