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This article deals with the design of a novel algorithm that combines a Modified Super-Twisting Controller with a High Order Sliding Mode Observer to enable an aerial vehicle to track a trajectory under the assumption that i) its translational velocities are unavailable and ii) there are unmodeled dynamics and external disturbances. We present a mathematical justification that ensures the existence...
Rapidly developing UAS technology necessitates reliable counter UAS systems. This paper proposes a formation controlled dragnet as a possible solution and compares potential intercept algorithms that can be used in this scenario. Proportional navigation and target-predictive path planning, both existing algorithms, are explored and an original approach, Adaptive Radius Optimal Defense (AROD), is introduced...
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...
This article proposes a control strategy based on the constrained generalized predictive control (GPC) in combination with a geometric attitude controller for trajectory tracking of the quadcopter vehicle. The generalized predictive control approach allows tracking time varying trajectories using optimal control actions to meet constraints on the desired trajectory. The geometric attitude controller...
Recently, the complexity of control systems for autonomous Aerial Manipulators (AMs), i.e. Unmanned Aerial Vehicle (UAV) + Robot Manipulator (RM), is growing faster as per our demand of being able to perform more and more complex tasks. In the present work, we go a step forward adding an optimiser to the actual (nonlinear) control strategy, in order to comply with high-level control demands related...
This paper presents a theoretical and practical implementation of a Kalman Filter (KF) to obtain the attitude and angular velocity from a nine degrees of freedom (DoF) inertial measurement unit (IMU). These include three DoF from an accelerometer, three from a magnetometer and the last three from a gyroscope. It differs from other attitude filters in two main aspects, the model representation and...
This paper deals with monocular image-based aircraft Sense and Avoid for small UAVs. After summarizing previous results of the authors it proposes a complete solution which calculates time to closest point of approach, relative closest point of approach (CPA) and the direction of intruder at CPA. These parameters are enough to make a collision decision and design the avoidance maneuver. The applicability...
This paper describes a problem in which a network consisting of a sensor-equipped UAV and multiple beacons, operating in a large geographical space, uses distance measurements to estimate the position of a target and pursue it. The positions of the beacon are also not known to the UAV and needs to be estimated by the UAV, again using distance measurements. Distance measurements are assumed to have...
A quadrotor is an underactuated unmanned aerial vehicle with four inputs to control the dynamics. Trajectory control of a quadrotor is a challenging task and usually tackled in a hierarchical framework where desired/reference attitude angles are analytically determined from the desired command signals, i.e. virtual controls, that control the positional dynamics of the quadrotor and the desired yaw...
Unmanned Aerial Vehicles (UAVs) exhibit great agility and usually require a trained pilot to operate them, while being restricted to line-of-sight range. This prevents their wide introduction in applications such as inspection for disaster scenarios. Our goal is to enable rescue teams untrained in piloting to teleoperate a UAV as an aid to their mission, while being able to focus on the task at hand...
As robotic technology matures, fully autonomous robots become a realistic possibility, but demand very complex solutions to be rapidly engineered. In order to be able to quickly set up a working autonomous system, and to reduce the gap between simulated and real experiments, we propose a modular, upgradeable and flexible hardware-in-the- loop (HIL) architecture, which hybridizes the simulated and...
In the context of Unmanned Aerial Vehicle (UAV) teleoperation, the platform is remotely controlled by a human pilot. In order to provide a better situational awareness to the pilot, haptic feedback can be sent through the controller to indicate the presence of obstacles around the UAV. This feedback makes obstacle avoidance easier for the pilot and complements the visual cues obtained from a camera...
In this study, we present a class of nonlinear analytical solutions for the dynamics of a fixed wing unmanned aircraft vehicle (UAV). These solutions are needed for the integration and fusion of sensor data for input to guidance and control algorithms. Derivation and integration of the 3-rd order vector differential equation of motion, and its applications to various dynamical models are presented...
The model-based event-triggered strategies have been developed as an alternate for Zero-Order-Hold (ZOH)- based event triggered scheme in continuous-time for multi-agent systems (MAS). However, traditional event-triggered schemes need the knowledge of system dynamics whereas model-based schemes are sensitive to model uncertainties. Therefore, in this paper, a novel distributed event-triggered consensus...
This paper deals with the design of a consensus algorithm for a multi-aircraft (type Quadrotor) leader-follower system. This algorithm uses directed communication topologies, as well as input saturation for the follower agents. The convergence analysis of the proposed strategies is analyzed by using Lyapunov stability theory. Semi-global asymptotic consensus tracking is obtained for the case of leader...
A nonlinear adaptive controller for an unmanned aerial vehicle (UAV) has been developed using Echo State Network (ESN), which is a form of three-layered recurrent neural network (RNN). Online learning is used to train the ESN in real-time starting from randomized weights. The ESN is integrated into ArduPilot, an open source autopilot, for complex flight simulations. Software-in-the-loop and hardware-...
This article addresses the trajectory-tracking problem for a miniature Quadrotor aircraft system using a super-twisting technique in real-time application. This strategy ensures the convergence in finite time to a desired programmed trajectory under bounded external perturbations such as wind gusts. The proposed solution consists of implementing a real-time strategy based on super-twisting control...
In this paper, a vision-aided terrain referenced navigation (VATRN) algorithm constructed by point-mass filter (PMF) is accelerated by graphic processing unit (GPU). The terrain referenced navigation algorithm estimates the vehicle's position by blending INS data with measured terrain height, and matching that data with the stored digital terrain elevation database (DTED). On the other hands, the...
With the rapid development of small imaging sensors and unmanned aerial vehicles (UAVs), remote sensing is undergoing a revolution with greatly increased spatial and and temporal resolutions. While more relevant detail becomes available, it is a challenge to analyze the large number of images to extract useful information. This research introduces a new general framework to process high-resolution...
This paper presents the development of an object path following algorithm for a quadcopter using on-board vision and localization. This development aims to increase capabilities of autonomous unmanned aerial vehicles (UAV), with the use of object path following. By following an object's path, reliance on obstacle avoidance strategies can be reduced, under the assumption that the object's path is free...
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