Jaret C. Riddick, PhD
Senior Fellow, CSET at Georgetown University
Virginia Polytechnic Institute and State University
Arlington, Virginia, United States
Further information is forthcoming
Dr. Francis Phillips
Research Qerospace Engineer
US Army DEVCOM Army Research Laboratory
Presentation Title: Development of an Integrated Baseless Small Unmanned Aerial System
Abstract: The use of small unmanned aerial systems (sUAS) has expanded dramatically over the last decade. These systems can be used for many applications ranging from communications to bridge inspections, agriculture, payload transport, firefighting, meteorology, and beyond. A current major limitation to the use of these systems is the available energy in these systems, whether through batteries or some other fuel source. Considering specifically sUAS weighing below 50 lbs., most of these sUAS are electrically powered and have nominal flight times of up to 60 minutes for long distance or duration applications where the primary purpose is information gathering and/or establishment of communications, it would be beneficial to find methods to conserve energy and potentially recharge the batteries. This talk will focus on development of an integrated sUAS capable of tracking, landing on, recharging, and releasing from existing powerlines, thereby enabling continuous operation of a sUAS without the need to return to a base station for recharging. The development of such an integrated system starts with the ability to track and fly along powerlines. Once the battery life reaches some minimum threshold, the integrated sUAS would grasp onto the powerline and an auxiliary electromagnetic system would be used to harvest the magnetic field emitted by the powerline, thereby recharging the sUAS batteries.
This talk is separated into three portions, each focusing on a separate portion of the proposed integrated system. First, efforts to develop a control scheme and morphing wings to track powerlines and subsequently match the natural curvature of powerlines through careful tuning of the long period oscillation for a fixed wing sUAS. This effort both includes the use of a time-of-flight sensor to locate powerlines, as well as the development of control laws and wing morphing mechanisms to follow the powerlines. Control laws were developed capable of considering a morphing parameter representative of changing the airfoil shape from a NACA 2410 to a NACA 2414, which is useful in tuning the phugoid mode. Simple prototypes have been developed capable of performing matching a commanded airfoil shape based on the control laws. The second portion considers efforts to develop an active gripper system to grasp, perch, and eventually release from an object such as a powerline or tree branch, thereby eliminating the motor power usage. Several different configurations of an active gripper system were developed and analyzed. These systems are designed to be bistable such that they can maintain an open configuration during flight as well as the closed configuration when perched. Furthermore, due to the bistable design, no energy is required to maintain either the open or grasped states but rather energy is only required when switching between states. The energy to grasp is provided via an impulse when the gripper strikes the object on which it will perch, enabling a rapid grasping motion without requiring additional energy input from the sUAS. Opening of the active grasper is enabled via the use of active materials (shape memory alloys or active polymers). Some of the developed systems are also prototyped and flight tested on a custom sUAS. The third portion of this talk will briefly discuss mechanisms to recharge the sUAS from the powerlines. All powerlines that carry a current will emit a magnetic field. Therefore, this integrated system will include an electromagnetic system to harvest such magnetic fields and use them to recharge the sUAS.
Biography: Dr. Francis Phillips currently works as a research aerospace engineer for the US Army DEVCOM Army Research Laboratory, where he leads a program focused on development of reconfigurable aerial vehicles including exploring the application and control of active materials to enable reconfiguration as well as aeroelastic analysis coupled to design for reconfigurable vehicles. Prior to joining the Army Research Laboratory, he earned his Ph.D. in Aerospace Engineering from Texas A&M University studying the fatigue of shape memory alloys. Dr. Phillips’ areas of interest include smart materials, reconfigurable structures, and aeroelasticity.