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This paper describes the development of a Sense and Avoid (S&A) algorithm that can ensure an Unmanned Aerial Vehicle (UAV) being able to avoid collisions autonomously. Firstly, the Closest Point of Approach (CPA) can predict the conflict. Secondly, the developed path planner generates the feasible path using differential geometric guidance and flatness techniques, where the constraints of UAV...
This paper details the design and performance assessment of a unique collision avoidance decision and control strategy for autonomous vision-based See and Avoid systems. The general approach revolves around re-positioning a collision object in the image using image-based visual servoing, without estimating range or time to collision. The decision strategy thus involves determining where to move the...
Detect and Avoid (DAA) technology is widely acknowledged as a critical enabler for unsegregated Remote Piloted Aircraft (RPA) operations, particularly Beyond Visual Line of Sight (BVLOS). Image-based DAA, in the visible spectrum, is a promising technological option for addressing the challenges DAA presents. Two impediments to progress for this approach are the scarcity of available video footage...
The diffusion of multirotors in different fields of application comes together with a variety of critical issues. For instance, they often have to operate close to high electric and magnetic fields, like in power lines areas. In order to ensure sufficient reliability in this kind of missions, a small quadcopter has been tested by performing electromagnetic compatibility tests. The experiment was carried...
In this paper, an unmanned aerial vehicle (UAV) based forest fire detection and tracking method is proposed. Firstly, a brief illustration of UAV-based forest fire detection and tracking system is presented. Then, a set of forest fire detection and tracking algorithms are developed including median filtering, color space conversion, Otsu threshold segmentation, morphological operations, and blob counter...
A fault tolerant cooperative control (FTCC) strategy for a team of an unmanned aerial vehicle (UAV) and unmanned ground vehicles (UGVs) in the presence of actuator faults are investigated in this paper. A combination of a linear model predictive control (MPC) and input-output feedback linearization is implemented on each UGV, while a combination of a sliding mode control and linear quadratic regulator...
The integration of Global Navigation Satellite System (GNSS) integrity augmentation functionalities in Unmanned Aerial Systems (UAS) has the potential to provide an integrity-augmented Sense-and-Avoid (SAA) solution suitable for cooperative and non-cooperative scenarios. In this paper, we evaluate the opportunities offered by this integration, proposing a novel approach that maximizes the synergies...
In this paper, we propose an Integrated Fault Tolerant Controller (IFTC) for quadrotor UAVs based on Sliding Mode Passive and Active FTCs, along with Trirotor conversion maneuver. A Sliding Mode Observer is used to detect and estimate actuator faults affecting rotors, and a fault severity based decision station activates the suitable controller. The new controller not only ensures fault tolerance,...
A group of unmanned vehicles can provide essential support to human task forces in a variety of missions, like in search and rescue operations. A crucial factor for task coordination is to maintain a reliable connectivity among the autonomous platforms. Radio-frequency is the common technology adopted for unmanned systems to operate wirelessly. However, this technology has some limitations that can...
This paper describes a technological development project in charge of collecting and relaying data using UAVs (Unmanned Aerial Vehicles) from one or more small, low power, modular sensor nodes that can be placed in remote areas or floating on the water surface. The overall characteristics and architecture of the proposed sensor nodes and system around them are described. Field tests for one custom-built...
In recent years, the technology of wireless sensor networks (WSNs) have evolved quickly leading to sensors with increased memory, storage, processing, and communication capabilities. WSNs have many applications in the commercial, environmental, and military fields. In addition, the technology of unmanned aerial vehicles (UAVs) has gone through revolutionary improvements, which have led to highly advanced...
This paper presents an overview of unmanned aircraft systems developed at the University of Colorado and the development of a new software defined radio sensor that will be integrated into the existing systems. The architecture and performance of the new sensor is discussed. Potential research applications enabled by the radio sensor are covered.
Scores of avalanche injuries and fatalities occur annually. This research presents an avalanche search and rescue (SAR) proof-of-concept option that utilizes a small unmanned aerial vehicle (UAV) helicopter with a payload capable of detecting and locating a buried victim's cell phone. Cell phones involved in this research were modern-day fourth generation (4G) Long Term Evolution (LTE) devices with...
In order for Remotely Piloted Aircraft Systems (RPAS) to coexist seamlessly with manned aircraft in non-segregated airspace, enhanced navigational capabilities are essential to meet the Required Navigational Performance (RNP) levels in all flight phases. A Multi-Sensor Data Fusion (MSDF) framework is adopted to improve the navigation capabilities of an integrated Navigation and Guidance System (NGS)...
Fixed wing Unmanned Aerial Vehicles (UAVs) are an increasingly common sensing platform, owing to their key advantages: speed, endurance and ability to explore remote areas. While these platforms are highly efficient, they cannot easily be equipped with air data sensors commonly found on their larger scale manned counterparts. Indeed, such sensors are bulky, expensive and severely reduce the payload...
The Extended Kalman Filter (EKF) and Unscented Kalman Filter (UKF) are methods usually applied in the sensor fusion for Unmanned Aerial Vehicles due to its nonlinear navigation equations. This paper presents a comparison between the two filters considering the position, velocity and attitude of the vehicle and the IMU bias. The simulation experiments are designed according to performance evaluation...
The Kalman filter is an algorithm used for data estimation and sensor fusion. It has been used for decades in several projects, especially in the aerospace industry, being the Apollo program for lunar explorations one of the first to apply the filter. As a way to analyze the practical Kalman filter application in real situations, this paper shows its use in the estimation of the horizontal attitude...
This paper proposed a framework for airborne multisensor management for multitarget tracking, considering each of multiple unmanned aircraft as a sensor. The purpose of the algorithm is to quantify the performance of the multitarget tracking and to determine the time and location of the sensor deployment. Utilizing the posterior Cramer-Rao lower bound, the inverse of the Fisher information matrix,...
Among the main sub-areas covering the cooperative control problem of Unmanned Aerial Vehicles (UAVs), formation flight has attracted great interest and has been widely investigated. The main purpose of the formation flight control is to establish a desired shape of formation for a group of vehicles by controlling the positions of each vehicle. The present paper deals with the problem of position formation...
Cooperative and non-cooperative Sense-and-Avoid (SAA) capabilities are key enablers for Unmanned Aircraft Vehicle (UAV) to safely and routinely access all classes of airspace. In this paper state-of-the-art cooperative and non-cooperative SAA sensor/system technologies for small-to-medium size UAV are identified and the associated multi-sensor data fusion techniques are introduced. A reference SAA...
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