Research and Technology

Langley Research Center is engaged in the basic an applied research necessary for the advancement of aeronautics and space flight, generating advanced concepts for the accomplishment of related national goals, and provding research advice, technological support, and assistance to other NASA installations, other government agencies, and industry. Highlights of major accomplishments and applications are presented

Empowering and assisting natural human mobility: The simbiosis walker

This paper presents the complete development of the Simbiosis Smart Walker. The device is equipped with a set of sensor subsystems to acquire user-machine interaction forces and the temporal evolution of user's feet during gait. The authors present an adaptive filtering technique used for the identification and separation of different components found on the human-machine interaction forces. This technique allowed isolating the components related with the navigational commands and developing a Fuzzy logic controller to guide the device. The Smart Walker was clinically validated at the Spinal Cord Injury Hospital of Toledo - Spain, presenting great acceptability by spinal chord injury patients and clinical staf

Regulating stepping during fixed-speed and self-paced treadmill walking

textBackground: Treadmill walking should closely simulate overground walking for research validation and optimal skill transfer. Traditional fixed-speed treadmill (FS) walking may not simulate natural walking because of the fixed belt speed and lack of visual cues. Self-paced (SP) treadmill walking, especially feedback controlled SP treadmill walking, enables close-to-real-time belt speed changes with users' speed changes. Different sensitivity levels of SP treadmill feedback determine how fast the treadmill respond to user's speed change. Few studies have examined the differences between FS and SP treadmill walking, or the difference between sensitivity levels of SP treadmills, and their methods were questionable because of averaging kinematics and kinetics parameters, and failing to examine directly treadmill and subjects' speed data. This study compared FS with two SP modes with variation of treadmill speed and user's speed as dependent variables. Method: Thirteen young healthy subjects participated. Subjects walked on a motorized split-belt treadmill under FS, high sensitivity SP (SP-H) and low sensitivity SP (SP-L) conditions at normal walking speed. Root mean square error (RMSE) for subject's pelvis global speed (Vpg), pelvis speed with respect to treadmill speed (Vpt), and treadmill speed (Vtg) data were collected for all trials. Results: Significant condition effects were found between FS and the two SP modes in all RMSE values (p < 0.001). The two sensitivity levels of SP had similar speed patterns. Large subject × condition interaction effects were found for all variables (p < 0.001). Only small subject effects were found. Conclusions: The results of the study reveal different walking patterns between FS and SP. However, the two sensitivity levels failed to differ much. More habituation time may be needed for subjects to learn to optimally respond to the SP algorithm. Future work should include training subjects for more natural responses, applying a feed-forward algorithm, and testing the effect of optic flow on FS and SP speed variation.Kinesiology and Health Educatio

Vibration-Induced Atomization Of Liquids With Application To Ultrasonic Medical Nebulizers

Existing literature on the operation of ultrasonic vibrating mesh nebulizers does not entirely explain the principles by which these devices atomize liquid medication. Many of the studies on this topic assume a spray or extrusion mode of droplet generation, but it can be demonstrated that the high frequency vibration of these devices is sufficient to produce appropriately-sized aerosol droplets. A sufficiently small volume or thin film of liquid that is vibrated under correct conditions will produce a fountain of atomized liquid droplets which are appropriately sized for transport and deposition deep into the lungs, which is necessary for inhalation therapy. The formation of standing waves on the surface of this sort of thin film have an oscillating frequency that is roughly half the driving frequency and a wavelength that is equal to a function of the ultrasonic driving frequency, fluid density, and interfacial surface tension. The standing wavelength in particular is shown to be approximately three times the mean droplet diameter that makes up the resulting spray. Also, several studies have shown that cavitation is likely to be present in vibrating films of water which destabilize the capillary waves and may alter the overall droplet diameter distribution of the resulting fountain. This study validates these phenomena by relating existing concepts of liquid atomization to the operating parameters of known atomizing systems and the Omron Micro Air vibrating mesh nebulizer, along with numerically altering these parameters to show trends in response conditions. A CFD analysis is performed which assists in model verification and reveals that some critical configuration driving amplitude and liquid depth must be fulfilled in order for droplet kinetic energy to exceed fluid resistance energy so that the atomization process can initiate. The Omron Micro Air operates at an ultrasonic frequency of approximately 180 kHz and is able to maintain a liquid film that is the correct thickness to generate capillary waves leading to droplet ejection. The vibrating mesh component is assumed to be largely responsible for maintaining this film thickness along with acting as a sizing screen to only release droplets that are 3 µm or smaller. The exact function of the vibrating mesh is not analyzed in detail during this study, as the primary focus is to verify and identify parameters of atomization of a thin film of water under the aforementioned operating conditions

MODELING AND PROTOTYPING A MODULAR, LOW-COST COLLISION AVOIDANCE SYSTEM FOR UAVS

Many challenges arise when attempting to use unmanned aerial vehicles (UAVs) in indoor environments, such as the lack of a GPS signal for use in navigation and the smaller margin of error in movements. Typically, those challenges are addressed by using a collision avoidance system. However, most commercially available collision avoidance systems are expensive, limited in suppliers, and are restricted to use on a specific platform. Additionally, some of the collision avoidance systems choose to forego obstacle detection in one or more directions, usually the upward direction. This work proposes that it is possible to develop a custom, low-cost collision avoidance system with modular capabilities, allowing it to be adapted to any UAV platform. The feasibility of the proposed system was determined by creating a single-direction prototype that was implemented on a small quadcopter and tested by flying the quadcopter towards a wall at slow speeds. To develop the system’s control algorithm a model of a quadcopter was built. Two different control algorithms were developed and tested via simulation with the model, and the better performing algorithm was implemented in the prototype. The feasibility of the proposed collision avoidance system is promising with the prototype able to prevent the quadcopter from colliding with a wall. However, further refinement in the methodology and techniques used to develop the system is needed to improve performance and reliability of the system, especially as obstacle detection is added in other directions of motion. Keywords

Langley aerospace test highlights, 1985

The role of the Langley Research Center is to perform basic and applied research necessary for the advancement of aeronautics and space flight, to generate new and advanced concepts for the accomplishment of related national goals, and to provide research advice, technological support, and assistance to other NASA installations, other government agencies, and industry. Significant tests which were performed during calendar year 1985 in Langley test facilities, are highlighted. Both the broad range of the research and technology activities at the Langley Research Center and the contributions of this work toward maintaining United States leadership in aeronautics and space research, are illustrated. Other highlights of Langley research and technology for 1985 are described in Research and Technology-1985 Annual Report of the Langley Research Center

A cyber-physical system for smart healthcare

Abstract: The increasing number of patients in hospitals is becoming a serious concern in most countries owing to the significantly associated implications for resources such as staff and budget shortages. This problem has prompted researchers to investigate low-cost alternative systems that may assist medical staff with monitoring and caring for patients. In view of the recent widespread availability of cost-effective internet of things (IoT) technologies such as ZigBee, WiFi and sensors integrated into cyber-physical systems, there is the potential for deployment as different topologies in applications such as patient diagnoses and remote patient monitoring...M.Tech. (Electrical and Electronic Engineering Technology

Aeronautical Engineering: A special bibliography with indexes, supplement 54

This bibliography lists 316 reports, articles, and other documents introduced into the NASA scientific and technical information system in January 1975

Rotational fluid flow experiment: WPI/MITRE advanced space design GASCAN 2

The design and implementation is examined of an electro-mechanical system for studying vortex behavior in a microgravity environment. Most of the existing equipment was revised and redesigned as necessary. Emphasis was placed on the documentation and integration of the mechanical and electrical subsystems. Project results include the reconfiguration and thorough testing of all the hardware subsystems, the implementation of an infrared gas entrainment detector, new signal processing circuitry for the ultrasonic fluid circulation device, improved prototype interface circuits, and software for overall control of experiment design operation

Fracture Toughness of a Hyperelastic Material During Surgical Cutting

Despite being one of the most important organs of vertebrates, the material properties of skin are also one of the most poorly understood. In the field of designing medical devices and surgical tools there are significant advantages to having a model that describes the interaction of forces between a blade tip and skin during surgical cutting. In general, skin can best be described as a composite layer consisting of a viscoelastic dermis with interwoven collagen and elastin fibers beneath a superficial epidermis. The purpose of this research is to study the fracture toughness of porcine skin during practical cutting applications, the behavior of skin under quasistatic loads, and viscoelastic behavior of skin during stress relaxation. To fully describe the mechanics of skin in this model tensile test are conducted to determine the material properties of skin. The fracture toughness of the material is calculated by measuring the energy release rate of the material during required during cutting with Number 11 scalpel blade with a tip radius of 12 [micro]m . These results are then compared to a finite element analysis with a debonding interface and a Mooney-Rivlin hyperelastic material model with viscoelastic relaxation in an effort to predict the loads required by tools during surgical applications. The main outcome of this research is the development of a testing protocol and material model of skin that can be used in finite element simulations of uniaxial loads and surgical cutting