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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...
This paper presents a novel approach to estimate the relative position of an aerial vehicle that is connected to a fixed location on the ground through a taut tether of varying length. The onboard commercial-of-the-shelf (COTS) inertial sensors are the only source of sensory data used for the proposed approach. A three-dimensional (3D) dynamics model of the tethered quadcopter system is presented...
This work presents the flight test validation of an autonomous nano quadrotor called Crazyflie 2.0 in arbitrary trajectory tracking. The complexity of the control tasks were due to the low rigidity and high flexibility of propellers and airframe components, high sensitivity of vehicle inertial dynamic model to the battery location, uncalibrated motors, and unsteady battery depletion rate. Keeping...
This paper describes an unmanned aerial vehicle (UAV) ice tracking framework for use in sea ice management applications. The framework is intended to be used in an ice management scenario where the UAV should detect and track the movement of icebergs and ice floes in an Arctic environment, and seeks to enable the UAV to do so autonomously. This is achieved by using an occupancy grid map algorithm...
Experimental and computational studies of the hovering performance of microcoaxial shrouded rotors were carried out. The ATI Mini Multi-Axis Force/Torque Transducer system was used to measure all six components of the force and moment. Meanwhile, numerical simulation of flow field around rotor was carried out using sliding mesh method and multiple reference frame technique by ANASYS FLUENT. The computational...
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 an optimized method to employ a team of multirotors for collecting images to generate a 3D map of an area with emphasis on special features (e.g. man-made structures) and areas of avoidance. When an area is too large to be mapped by one multirotor within its battery life, then either several flights or several multirotors need to be employed to complete the job. This paper introduces...
In this paper, an approach to estimate the mass of a quadcopter using only inertial measurements and pilot commands is presented. For this purpose, a lateral dynamic model describing the relation between the roll rate and the lateral acceleration is formulated. Due to the quadcopter's inherent instability, a controller is used to stabilize the system and the data is collected in closed loop. Under...
The present paper describes the design of a nonlinear flight control method for a fixed-wing UAV using an extended state observer (ESO). The dynamics of a UAV contains uncertainties such as modeling error and actuator dynamics that deteriorate control performance. Moreover, wind disturbance seriously affects stability with respect to the dynamics of a small UAV. The ESO can estimate not only the state...
Taken together, recent advances in microelectromechanical systems, wireless mesh networks, digital circuits, and battery technology have made the notion of autonomous pico air vehicles viable. In this work we describe the core technologies enabling these future vehicles as well as propose two possible future platforms. We draw on recent research on high thrust density atmospheric ion thrusters, microfabricated...
This paper addresses the problem of trajectory tracking for underactuated quadrotors. A quaternion based guidance law is proposed which feeds into an attitude control system based on a PD+ control law. The desired attitude from the guidance law is defined such that the attitude control system tries to align the position error along the axis of the translational actuator. Simulation results are provided...
A number of autonomous unmanned aerial vehicles (UAV) are tasked to search an unknown/uncertain environment, and neutralize targets whenever they come across such threats. Due to resource constraints of the UAVs, neutralizing some threats require simultaneous effort of a certain number of UAVs in minimum. When a UAV detects multiple such targets which require team efforts, it needs to communicate...
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...
Small unmanned aircraft systems (UAS) typically do not offer the redundancy typical in commercial aviation due to budget and weight limitations. UAS, therefore, have a nontrivial probability of encountering a scenario in-flight that requires an emergency landing. For fixed-wing UAS, one of the most common in-flight emergencies is a total loss of engine or motor thrust, necessitating that the UAS glide...
UAVs provide exceptional capabilities and a myriad of potential mission sets, but the ability to disguise where the aircraft takes off and lands would expansively advance the abilities of UAVs. This paper describes the development of a nonlinear estimation algorithm to predict the terminal location of an aircraft and a trajectory optimization strategy to mitigate the algorithm's success. A recursive...
In polar region operations, drift ice positioning and tracking is useful for both scientific and safety reasons. Many sensors can be employed to generate detections of sea ice, such as satellite-carried Synthetic Aperture Radar (SAR) and, recently, imagery equipment carried by Unmanned Aerial Systems (UAS). Satellite-carried SAR has the advantage of being able to cover large areas and provide consistent...
We describe an analytical process to determine how much UAS traffic is feasible. The process is a simulator and data processing tools. The two are applied to the US San Francisco Bay Area and Norrköping, Sweden. The amount of UAS traffic is measured in flights per day and simulated up to 200,000 flights. A UAS traffic volume is feasible if specified metrics meet operational requirements with high...
This work proposes an adaptive dynamic controller for an unmanned aerial vehicle (UAV) to track a desired trajectory. Initially, reference velocities are generated by a controller that is based only on the kinematic model of the UAV. Subsequently, new control actions are calculated to compensate for the internal dynamics of the robot. Then the model parameters that characterize the robot dynamics...
In this study, we investigate the feasibility of detecting small intruder aircraft through camera images obtained onboard a small unmanned aircraft. The research group (Small Unmanned Aerial Vehicle Laboratory) from NASA Langley Research Center flew a set of missions with their small UAS (sUAS) where one of those vehicles is outfitted with three 4K resolution cameras located at the tips of the wings...
Unmanned aircraft flying beyond line of sight in uncontrolled airspace need to maintain adequate separation from local inclement weather patterns for regulatory compliance and operational safety. Although commercial solutions for ‘weather avoidance’ exist, they are tailored to manned aviation and as such either lack the accuracy or the size, weight, and power (SWaP) requirements of small Unmanned...
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