Terence Haran

Diagnostic Capabilities for Electromagnetic Railguns

In the past 30 years, there have been significant advances in the development of modeling and simulation algorithms for electromagnetic railguns. The development of instrumentation capable of measuring the physical parameters that occur during a high-velocity launch, however, has not kept pace with the advances in modeling capabilities. In addition, there has been an increase in the size and complexity of existing railguns, and therefore it has become necessary to find instrumentation that has the flexibility to conform to the variations present from one railgun to the next, to aid in the cross-utilization of instrumentation across the community. This paper will describe results from Georgia Tech and U.S. Navy to evaluate diagnostic techniques that measure different phenomena at higher resolution in both time and space in order to provide the data needed to validate railgun models. The diagnostics described here address all aspects of railgun testing, including the launcher, projectile, and pulsed power supplies and all phases of the evaluation process from validation of modeling and simulation tools to structural health monitoring. Specific quantities for which diagnostics will be described include temperature, electric and magnetic field sensors, and strain measurements. Examples of electromagnetic sensors that will be presented include colossal magnetoresistance sensors, which respond to changes in a magnetic field with a change in resistance, and a slab-coupled optical sensor for detecting electric fields. Test results from railguns at both Georgia Tech and the French-German Institute in Saint-Louis will be described.

Stress Wave Measurements in an Electromagnetic Launcher

This paper discusses strain measurements that were conducted on the electromagnetic rail launcher at the Georgia Institute of Technology. The dynamic strain in the rails of the launcher was measured using fiber Bragg grating strain sensors with an interrogation system developed by micron optics. The fiber optic sensors are immune to the large pulsed electromagnetic fields in the bore of the launcher. The immunity of this system to electromagnetic interference allowed for dynamic strain measurements to be made during launch. These measurements show changes in the dynamic strain that are indicative of a critical velocity of the rails. These changes include wave radiation, wave reflection and strain amplification above the critical velocity. The magnitude of the stress waves are large enough for plastic deformation of the rails to occur. This plastic deformation could directly affect the lifetime of the rails in the electromagnetic launcher. The apparent critical velocity seen in these experiments is lower than the value from the Bernoulli-Euler beam theory. This is believed to be caused by a combination of the nonlinear load-deflection curve and effective mass of the containment. In addition to these phenomena, jerk effect waves and asymmetries between the two different rails were also observed.

Diagnostic capabilities for electromagnetic railguns

In the past 30 years, there have been significant advances in the development of modeling and simulation algorithms for electromagnetic railguns. The development of instrumentation capable of measuring the physical parameters that occur during a high velocity launch, however, has not kept pace with the advances in modeling capabilities. In addition, there has been an increase in the size and complexity of existing railguns and therefore it has become necessary to find instrumentation that has the flexibility to conform to the variations present from one railgun to the next, to aid in the cross-utilization of instrumentation across the community. This paper will describe results from Georgia Tech and Navy efforts to evaluate diagnostic techniques that measure different phenomenon at higher resolution in both time and space in order to provide the data needed to validate railgun models. The diagnostics described here address all aspects of railgun testing, including the launcher, projectile, and pulsed power supplies and all phases of the evaluation process from validation of modeling and simulation tools to structural health monitoring. Specific quantities for which diagnostics will be described include temperature, electric and magnetic field sensors, and strain measurements. Examples of electromagnetic sensors that will be presented include colossal magneto-resistance (CMR) sensors, which respond to changes in a magnetic field with a change in resistance, and a slab coupled optical sensor (SCOS) for detecting electric fields. Test results from railguns at both Georgia Tech and ISL will be described.

Handheld thermal imaging for law enforcement and counterdrug applications

Although the potential benefits of infrared imaging systems in law enforcement applications have been apparent for many years, budget and technology constraints have prevented their widespread deployment. Recent technology improvements and cost reductions, however, have made the routine use of handheld thermal imagers practical for the law enforcement community. This effort involved both an analysis of operational and technical requirements associated with law enforcement use as well as a comprehensive review of commercially available handheld infrared imaging systems. The use of handheld infrared systems in the counterdrug environment is also addressed, including the results of an analysis of proven applications, a review of training requirements, and a summary of legal issues associated with infrared surveillance. Results generated by the NVTHERM infrared sensor model are also shown for one handheld imager to provide representative information regarding low-cost thermal imager performance.

Improved night vision demonstrator program status

Although existing night vision equipment provides a significant improvement in target detection in low light conditions, there are several limitations that limit their effectiveness. Focus is a significant problem for night vision equipment due to the low f-number optics required to obtain sufficient sensitivity as well as the dynamic nature of night vision applications, which requires frequent focus adjustments. The Georgia Tech Research Institute has developed a prototype next-generation night vision device called the Improved Night Vision Demonstrator (INVD) in order to address these shortfalls. This paper will describe the design of the INVD system as well as an analysis of its performance.

In Situ Measurement of Strain and Temperature for Railgun Launcher Diagnostics

The challenging physical environment associated with electromagnetic launchers (EMLs) makes reliable in situ measurements of physical parameters particularly difficult. The resulting lack of data hinders the validation of simulation codes that are used to support the design of new EMLs. As a result, there have been substantial efforts to develop new instrumentation that is compatible with the harsh environment of an EML. This paper will describe recent developments from Georgia Tech and U.S. Navy research to improve instrumentation capabilities for temperature and strain.

Infrared reflectivity of pedestrian mannequin for Autonomous Emergency Braking testing

In order to be able to evaluate the performances of different Autonomous Emergency Braking (AEB) systems for pedestrian crash avoidance and mitigation, a standard surrogate pedestrian mannequin needs to be developed. One of the requirements for pedestrian mannequin is to ensure it “looks” like a real representative pedestrian to each of the sensor modalities used in AEB systems. The purpose of this paper is to generate the recommended IR reflectance specifications for the standard surrogate pedestrian mannequin based on the collected data from various sources and the experiments.

In situ temperature and strain instrumentation for harsh electromagnetic environments

The challenging physical environment associated with electromagnetic launchers (EMLs) makes reliable in situ measurements of physical parameters particularly difficult. The resulting lack of data hinders the validation of simulation codes that are used to support the design of new electromagnetic launchers. As a result, there have been substantial efforts to develop new instrumentation that is compatible with the harsh environment of an electromagnetic launcher. This paper will describe recent developments from Georgia Tech and US Navy research to improve instrumentation capabilities for temperature and strain.

Hands-Free Focus Night Vision Technology Demonstration

The Georgia Tech Research Institute is currently developing a device to demonstrate a hands-free focus technology for head-mounted night vision sensors. The demonstrator device will integrate a computational imaging technique that increases depth of field with a digital night vision sensor. The goal of the demonstrator is to serve as a test bed for evaluating the critical performance/operational parameters necessary for the hands-free focus technology to support future tactical night vision concepts of operation. This paper will provide an overview of the technology studies and design analyses that have been performed to date as well as the current state of the demonstrator design.