System analysis and design of a low-cost micromechanical seeker system

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2008.Includes bibliographical references (p. 137-140).Precision guided targeting systems have been in use by the U.S. military for the last half-century. The desire for high targeting accuracies while maintaining minimal collateral damage has driven the implementation of guidance systems on a myriad of different platforms. Current seeker systems using global positioning system (GPS)-aided technology offer good accuracy, but are limited by an adversary's signal jamming capabilities and the dynamic nature of the military target environment. Furthermore, ultra-accurate inertial measurement units (IMU) that serve as stand-alone guidance systems are very expensive and offer no terminal guidance enhancement. As a result, it is cost prohibitive to equip some platforms with precision guidance capability. The demand for high accuracy at low cost has prompted substantial recent development of micro-electromechanical systems (MEMS) IMU's and optical focal plane arrays (FPA). The resulting decreasing device size and production costs coupled with higher unit performance have created opportunities for implementing seeker-enabled systems on platforms previously deemed impractical. As a result, the author proposes a design methodology to develop a low-cost system while satisfying stringent performance requirements. The methodology is developed within the context of a strap-down seeker system for tactical applications. The design tenets of the optical sensor, the inertial sensor, and projectile flight dynamics were analyzed in-depth for the specific scenario. The results of each analysis were combined to formulate a proposed system.(cont.) The system was then modeled to produce system miss distance estimates for differing engagement situations. The system demonstrated 3[sigma] miss distance estimates that were less than the maximum allowable error in each case. The system cost was tabulated and a production price was approximated. Using current technology and pricing information for the main components, the analysis shows that a system with a 3[sigma] miss distance of 0.801 m could be built for a unit price in the range of $11,730 -$19,550, depending on production costs. Design limitations are discussed, as well as strategies to improve the analysis for future consideration.by Brian J. Nagle.S.M

A Novel Approach to Imaging using a Dual Field-of-View Sensor

Most modern aircraft, such as missile systems and unmanned aerial vehicles have limited size, weight, power and cost (SWaP-C) capability. As the defence budget for military forces such as the UK and US continue to shrink, the emphasis on SWaP-C continues to strengthen. Military forces require smart weapons capable of precision strike, with a priority on safety. System manufacturers understand these requirements and limitations, and in response, develop miniaturised systems and components and also aim to consolidate these, into a single miniaturised solution. The growth of remotely operated aircraft, offers an ever present need for better, cheaper imaging systems. In general, sensors and seekers tend to be the biggest contribution to the cost and weight of an aircraft. Often, multiple imaging systems are needed dependent on the operational requirements. In this thesis, a novel dual field-of-view imaging system/seeker is proposed, which uses a single imaging sensor to superimpose both a wide field-of-view and a narrow field-of-view image of the same scene, co-boresighted. This allows multiple operational requirements to function simultaneously. The wide field-of-view allows for continuous monitoring and surveillance of an area, whilst the narrow field-of-view enables target detection, identification and tracking capabilities. Secondly, this thesis proposes a novel image separation technique to facilitate the separation of the superimposed imagery, using only the geometric relationship between the two different field-of-views. The separation technique is then extended to operate over sequential frames (i.e. video), and to function with fixed cameras that exhibit (un)desired camera motions, such as vibrations or "jitter". The image quality of the separation technique is broadly analysed over a range of images with varying image characteristics and properties. A novel image quality metric (IQM) was also proposed in this thesis, and was used to analyse the image quality of the recovered images, and its performance compared to already available IQMs. Finally, the separation technique is enhanced to operate with motion cameras, which exhibit motions such as pan, tilt, zoom and rotate etc. The separation technique, in most cases, was found to provide image recovery, comparable to current image enhancement techniques, and moreover, found to be far more robust to errors in registration, compared to current techniques. Initial hardware designs for the dual field-of-view imaging system, designed in conjunction with Prof. Andy Harvey from the University of Glasgow and Dr. James Babbington from Qioptiq Ltd., a lens design and manufacturing company, has also been presented

DESIGN AND TESTING OF A MULTI-UNIT PAYLOAD DELIVERY AND TRACKING SYSTEM FOR GUIDED MUNITIONS TO COMBAT UAV SWARM THREATS

A growing problem facing national security revolves around inexpensive, easily manufactured drones. Sophisticated software can link drones into swarms and inflict heavy damage on the United States and her allies’ assets, while rudimentary drones could also be used by terrorists to strike civilians from afar. Current defenses against drone swarms are conventional missiles that can cost hundreds of thousands of dollars; the disproportion in cost is not in U.S. favor. The NPS Rocket Propulsion Lab has explored the design of a low-cost delivery vehicle capable of deploying multiple guided munitions laterally out of the missile body at an altitude greater than that of the drone swarm. The guided munitions would be tasked by a targeting hub that would remain aloft above the specific drones, providing unique guidance commands to each deployed unit. This thesis focused on the deployment of the munitions from a flight system, utilizing both Computational Fluid Dynamics and real flight testing to design an effective ejection mechanism and tracking approach. Additionally, high-level design and analysis of a targeting system within the missile was performed. Although there are many solutions being explored to this pressing problem, this thesis seeks to give the United States more cost-symmetric options and capabilities when it comes to air defense against drone swarms in the future.http://archive.org/details/designandtesting1094562706Ensign, United States NavyApproved for public release; distribution is unlimited

Visual versus visual-inertial guidance in hawks pursuing terrestrial targets

The aerial interception behaviour of falcons is well modelled by a guidance law called proportional navigation, which commands steering at a rate proportional to the angular rate of the line-of-sight from predator to prey. Because the line-of-sight rate is defined in an inertial frame of reference, proportional navigation must be implemented using visual-inertial sensor fusion. In contrast, the aerial pursuit behaviour of hawks chasing terrestrial targets is better modelled by a mixed guidance law combining information on the line-of-sight rate with information on the deviation angle between the attacker’s velocity and the line-of-sight. Here we ask whether this behaviour may be controlled using visual information alone. We use high-speed motion capture to record n=228 flights from N=4 Harris’ hawks Parabuteo unicinctus, and show that proportional navigation and mixed guidance both model their trajectories well. The mixed guidance law also models the data closely when visual-inertial information on the line-of-sight rate is replaced by visual information on the motion of the target relative to its background. Although the visual-inertial form of the mixed guidance law provides the closest fit, all three guidance laws provide an adequate phenomenological model of the behavioural data, whilst making different predictions on the physiological pathways involved

Robust Image-Based Visual Servo Control of an Uncertain Missile Airframe

A nonlinear vision-based guidance law is presented for a missile-target scenario in the presence of model uncertainty and unknown target evasive maneuvers. To ease the readability of this thesis, detailed explanations of any relevant mathematical tools are provided, including stability definitions, the procedure of Lyapunov-based stability analysis, sliding mode control fundamentals, basics on visual servo control, and other basic nonlinear control tools. To develop the vision-based guidance law, projective geometric relationships are utilized to combine the image kinematics with the missile dynamics in an integrated visual dynamic system. The guidance law is designed using an image-based visual servo control method in conjunction with a sliding-mode control strategy, which is shown to achieve asymptotic target interception in the presence of the aforementioned uncertainties. A Lyapunov-based stability analysis is presented to prove the theoretical result, and numerical simulation results are provided to demonstrate the performance of the proposed robust controller for both stationary and non-stationary targets

1995 BRAC Commission

Navy - Air War Center, Technical Centers and Labs, China Lake, CA - Data Call (Part 2 of 2) June 15, 1994. Box 175, L-107

Defense Acquisitions: Assessments of Major Weapon Programs

A letter report issued by the General Accounting Office with an abstract that begins "The weapons the Department of Defense (DOD) develops have no rival in superiority. How they are developed can be improved, without sacrificing the superiority of the outcome. GAO's reviews over the past 20 years have found consistent problems with weapon investments--cost increases, schedule delays and performance shortfalls--along with underlying causes, such as pressure on managers to promise more than they can deliver. The best practices of successful product developments offer a knowledge-based approach DOD can use to improve the way it develops new weapons. This report is new for GAO, and draws on its work in best practices for product development. GAO's goal for this report is to provide congressional and DOD decision makers with an independent, knowledge-based assessment of defense programs that identifies potential risks, and offers an opportunity for action when a program's projected attainment of knowledge diverges from the best practice. It can also highlight those programs that employ practices worthy of emulation by other programs. GAO plans to update and issue this report annually to the congressional defense committees.

Performance factors for airborne short-dwell squinted radar sensors

Millimetre-wave radar in a missile seeker for the engagement of ground targets allows all-weather, day and night, surface imaging and has the ability to detect, classify and geolocate objects at long ranges. The use of a seeker allows intelligent target selection and removes inaccuracies in the target position. The selection of the correct target against a cluttered background in radar imagery is a challenging problem, which is further constrained by the seeker’s hardware and flight-path. This thesis examines how to make better use of the components of radar imagery that support target selection. Image formation for a squinted radar seeker is described, followed by an approach to automatic target recognition. Size and shape information is considered using a model-matching approach that is not reliant on extensive databases of templates, but a limited set of shape-only templates to reject clutter objects. The effects of radar sensitivity on size measurements are then explored to understand seeker operation in poor weather. Size measures cannot easily be used for moving targets, where the target signature is distorted and displaced. The ability to detect, segment and measure vehicle dimensions and velocity from the shadows of moving targets is tested using real and simulated data. The choice of polarisation can affect the quality of measurements and the ability to reject clutter. Data from three different radars is examined to help to understand the performance using linear and circular polarisations. For sensors operating at shorter ranges, the application of elevation monopulse to include target height as a discriminant is tested, showing good potential on simulated data. The combination of these studies offers an insight into the performance factors that influence the design and processing of a radar seeker. The use of shadow imagery on short-dwell radar seeker imagery is an area offering particular promise

Electronic warfare self-protection of battlefield helicopters : a holistic view

The dissertation seeks to increase understanding of electronic warfare (EW) self-protection (EWSP) of battlefield helicopters by taking a holistic (systems) view on EWSP. It also evaluates the methodologies used in the research and their suitability as descriptive tools in communication between various EWSP stakeholders. The interpretation of the term "holistic view" is a central theme to the dissertation. The research methodology is bottom-up – which is necessary since no previous work exists that could guide the study – and progresses from analysis to synthesis. Initially several methods are evaluated for presenting findings on EWSP, including high-level system simulation such as Forrester system dynamics (FSD). The analysis is conducted by a comprehensive literature review on EW and other areas that are believed to be of importance to the holistic view. Combat scenarios, intelligence, EW support, validation, training, and delays have major influence on the effectiveness of the EWSP suite; while the initial procurement decision on the EWSP suite sets limits to what can be achieved later. The need for a vast support structure for EWSP means that countries with limited intelligence and other resources become dependent on allies for support; that is, the question of EWSP effectiveness becomes political. The synthesis shows that a holistic view on EWSP of battlefield helicopters cannot be bounded in the temporal or hierarchical (organizational) senses. FSD is found to be helpful as a quality assurance tool, but refinements are needed if FSD is to be useful as a general discussion tool. The area of survivability is found to be the best match for the holistic view – for an EWSP suprasystem. A global survivability paradigm is defined as the ultimate holistic view on EWSP. It is suggested that future research should be top-down and aiming at promoting the global survivability paradigm. The survivability paradigm would give EWSP a natural framework in which its merits can be assessed objectively.reviewe

Joint ACCESS: high-speed assault connector (HSAC) for joint expeditionary logistics

Includes suppmentary materialThe current notion of seabasing requires that three Battalion Landing Teams (BLT) of a 2025 Joint Expeditionary Brigade (JEB) need to be able to transit from the Sea Base to the objective within a 10 hour period. Of the three BLTs, two of them must be transported by surface craft a distance of no more than 200nm in sea state 4 or less. The two surface bound BLTs need to be loaded onto the transporting craft and delivered to shore, whether it is a port facility or austere beachhead. There is no current or future system of connectors to meet all the time-distance, sea state, and interface flexibility requirements for this aspect of seabasing. To meet these requirements a High Speed Assault Connector (HSAC) is needed which either augments current or replaces existing connector platforms to deliver and support the required forces ashore. The Joint ACCESS is a HSAC that brings the necessary speed, payload capacity, interface capability, and mission flexibility needed to fill the Sea Base to shore transportation gap. With a maximum speed of 43kts and payload capacity of 800LT, 12 Joint ACCESS trimarans can transit 200nm and fully offload in 7 hours. Its beachable design uses a floating bow ramp to reach out to austere beaches, while its combat system suite provides self defense in addition to robust offensive capabilities.http://web.archive.org/web/20050218202650/http://www.nps.navy.mil/tsse/files/2004.htmApproved for public release; distribution is unlimited