Charles W. Hewgley

Performance, Control, and Simulation of the Affordable Guided Airdrop System

This paper addresses the development of an autonomous guidance, navigation and control system for a flat solid circular parachute. This effort is a part of the Affordable Guided Airdrop System (AGAS) that integrates a low-cost guidance and control system into fielded cargo air delivery systems. The paper describes the AGAS concept, its architecture and components. It then reviews the literature on circular parachute modeling and introduces a simplified model of a parachute. This model is used to develop and evaluate the performance of a modified bang-bang control system to steer the AGAS along a pre-specified trajectory towards a desired landing point. The synthesis of the optimal control strategy based on Pontryagins principle of optimality is also presented. The paper is intended to be a summary of the current state of AGAS development. The paper ends with the summary of the future plans in this area.

Mobile system for precise aero delivery with global reach network capability

This paper discusses the current status of the development of the mobile aerial delivery system to be further employed in a variety of different applications. High accuracy of the developed system enables its use in precision troop resupply, precise sensors placement, urban warfare reconnaissance and other similar operations. This paper overviews the overall system architecture and components of the developed aero delivery system itself and then proceeds with describing the current status of integrating it with an advanced deployment platform, unmanned aerial system, to achieve mobility and autonomy of operations. The paper also discusses some other systems in development pursuing similar goals and reviews some novel applications that become possible with the developed aerial delivery system.1

Precision Guided Airdrop for Vertical Replenishment of Naval Vessels

Abstract : This paper addresses the investigation into the feasibility of the use of precision guided airdrop as a means to deliver cargo to naval vessels at sea. In this context, precision guided airdrop means delivering unmanned cargo packages that, once dropped from an aircraft at high altitude, have the capability to guide themselves to a precise landing point by con- trolling an aerodynamic decelerator (parafoil or parachute) to which the cargo package is attached. The paper describes the problem of replenishment of naval vessels at sea and describes the benefits that the application of precision airdrop might provide. Improved accuracy of aerial delivery systems is the major focus of analysis, and how the application of model predictive control has potential to achieve the necessary improvements in accuracy that would make shipboard landings possible. A simple example is developed of a model predictive control algorithm adapted to track a target landing area that is moving with constant velocity. Additional techniques are also surveyed, as well as other potential applications of precision airdrop to maritime operations.

Shipboard Landing Challenges for Autonomous Parafoils

This paper examines some of the challenges that must be overcome if future aerial delivery systems are to have the capability to land on the flight deck of a ship underway. The unique aspects of trajectory planning for landing on a ship’s flight deck are first examined, followed by formulation of the position estimation problem for a moving target. Some preliminary investigations into characterizing the wind over a moving landing platform at sea are then described. Finally, experimental results are presented for testing of a small prototype autonomous parafoil with a simple moving target on land.

Autonomous Aerial Payload Delivery System “Blizzard”

Abstract : This paper presents a self-contained aerial payload/sensor delivery system Blizzard and discusses its potential applications.

Improved Surface Layer Wind Modeling for Autonomous Parafoils in a Maritime Environment

This paper investigates the use of atmospheric boundary layer theory to produce more accurate wind estimates for guiding an autonomous parafoil during the last portion of its flight before touchdown. The problem of wind estimation for a prototype autonomous parafoil aerial delivery system is first explained, followed by the simple assumptions for wind estimation that its guidance algorithm makes. A logarithmic wind profile model in the atmospheric surface layer is then introduced. The parameters and limitations of this model are discussed, along with the characteristics of this model that make it especially useful over the surface of the ocean. Finally, the incorporation of this model into the guidance algorithm of the prototype aerial delivery system is discussed, and subsequently evaluated in flight tests against the original algorithm that did not include the logarithmic surface layer wind model.

Use of bio-loggers to characterize red fox behavior with implications for studies of magnetic alignment responses in free-roaming animals

Background Spontaneous magnetic alignment (SMA), in which animals position their body axis in fixed alignments relative to magnetic field lines, has been shown in several classes of vertebrates and invertebrates. Although these responses appear to be widespread, the functional significance and sensory mechanism(s) underlying SMA remain unclear. An intriguing example comes from observations of wild red foxes (Vulpes vulpes) that show a ~fourfold increase in hunting success when predatory ‘mousing’ attacks are directed toward magnetic north-northeast. This form of SMA is proposed to receive input from a photoreceptor-based magnetoreception mechanism perceived as a ‘visual pattern’ and used as a targeting system to increase the accuracy of mousing attempts targeting hidden prey. However, similar to previous observational studies of magnetic orientation in vertebrates, direct evidence for the use of magnetic cues, and field-based experiments designed to characterize the biophysical mechanisms of SMA are lacking. Here, we develop a new approach for studies of SMA using triaxial accelerometer and magnetometer bio-loggers attached to semidomesticated red foxes.ResultsAccelerometer data were recorded from 415 ground-truth events of three behaviors exhibited by an adult red fox. A 5-nearest neighbor classifier was developed for behavioral analysis and performed with an accuracy of 95.7% across all three behaviors. To evaluate the generalizability of the classifier, data from a second fox were tested yielding an accuracy of 66.7%, suggesting the classifier can extract behaviors across multiple foxes. A similar classification approach was used to identify the fox’s magnetic alignment using two 8-way classifiers with differing underlying assumptions to distinguish magnetic headings in eight equally spaced 45° sectors. The magnetic heading classifiers performed with 90.0 and 74.2% accuracy, suggesting a realistic performance range for a classifier based on an independent set of training events equal in size to our sample.ConclusionsWe report the development of ‘magnetic ethograms’ in which the behavior and magnetic alignment of foxes can be accurately extracted from raw sensor data. These techniques provide the basis for future studies of SMA where direct observation is not necessary and may allow for more sophisticated experimental designs aimed to characterize the sensory mechanisms mediating SMA behavior.

Miniature Autonomous Rocket Recovery System (MARRS)

This paper discusses the development and testing of the new-generation recovery system in highpowered rockets. It starts from the overall description of the rocket system, the requirements of the Miniature Autonomous Rocket Recovery System (MARRS) and is followed by a description of a flight tested MARRS. Next, simulation and results from the flight tests are given. This paper ends with conclusions and recommendations for follow-on testing.

Visual Pose Estimation for Shipboard Landing of Autonomous Parafoils

This paper outlines an investigation into the use of a simple, focal-plane imaging sensor for guidance of an autonomous parafoil system for approach and landing on a moving platform such as a ship underway. The perspective-projective transformation between an object in a three-dimensional world and an image on a two-dimensional plane is analyzed and then formulated using a homogeneous coordinate system. The estimation problem is addressed; specifically, the challenge of dealing with the out-of-frame condition due to parafoil oscillation as it approaches the target. A dual-mode Kalman estimation-scheme is proposed that suspends measurement when the target is out-of-frame, and incorporates a two-view measurement when the target reenters the frame.