Agustin, R.M. et al.

Anszperger, J. et al.

Bedrossian, N.S. et al.

Bernstein, J. et al.

Borenstein, J.T. et al.

Chaudhry, A.I. et al.

Elwell, J.

Hall, W.D. et al.

Kourepenis, A.

Kwan, A. et al.

Nazarenko, A.I. et al.

Oh, J. et. al.

Schwartz, G. et al.

Shenai, S. et al.

Sitomer, J. et al.

Stoll, J.C. et al.

Vytal, J.J.

Weinberg, M.S.

Agustin, R.M.; Mangoubi, R.S.; Hain, R.M.; Adams, N.J.

Robust Failure Detection for Reentry Vehicle Attitude Control Systems

Journal of Guidance Control and Dynamics, Vol. 22, No. 6, Nov-Dec, 1999, pp. 839-845. (Draper Report no. P-3624-REV-B)

Abstract: This paper presents a robust failure detection methodology for the attitude control system of reusable launch vehicles (RLVs). In particular, we consider the problem of estimating the thrust from multiple jets firing from an RLV reaction control system (RCS), as well as the related problem of distinguishing between failures in the RCS and the aerosurfaces. For accurately known vehicle and sensor models, the Kalman filter provides the optimal estimate for the jet thrust in the least-squares sense. During reentry, however, plant model uncertainties are a major problem for such a filter, as the vehicle's aerodynamics vary widely with rapidly changing Mach number, making gain scheduling impractical. Consequently, the Kalman filter's performance degrades. Even if the Mach number were known accurately, rapid gain scheduling may not be desirable or even possible, because of the large data storage requirements it entails. Transient, robust H-infinity or game-theoretic filters are proposed for next-generation RLVs, and a prototype design is demonstrated for the Space Shuttle Orbiter's attitude determination system. Simulation results demonstrate that the robust filters can be insensitive to plant model uncertainties over a much wider range of Mach numbers than a traditional Kalman filter, while remaining sensitive to failures in the aerosurfaces and the RCS jets.

Subjects: ROBUST FAILURE DETECTION AND ISOLATION (RFDI), ATTITUDE CONTROL SYSTEMS, REUSABLE LAUNCH VEHICLES, REACTION CONTROL SYSTEMS (RCS), KALMAN FILTERING, ORBITER SPACECRAFT, FAILURE ANALYSIS, REENTRY VEHICLES, ROBUSTNESS (MATHEMATICS), COMPUTER SIMULATION

Anderson, J.M.; Parry, J.R.; Prestero, M.G.

Vorticity Control Propulsion and Maneuvering: an Enabler of Unique Asymmetric UUV Missions

Submarine Technology Symposium. Held at Johns Hopkins University (JHU), MD, 05/11/1999 to 05/13/1999. Sponsored by: JHU Applied Physics Laboratory (APL). (Draper Report no. P-3727)

Abstract: Analysis and experiments by M. Triantafyllou and others at the Massachusetts Institute of Technology (MIT) and elsewhere indicated that vorticity control (VC)-based propulsion and maneuvering concepts (employing fish-like motions to move man-made vehicles) offer the potential for high propulsion efficiency, exceptional maneuvering capability, and improved stealth for unmanned undersea vehicle warfare missions. Subsequent development at Draper Laboratory of a prototype vehicle using VC propulsion and maneuvering has reached the point of demonstrating the feasibility of this method of propulsion and has given initial confirmation of the potential for improved propulsion efficiency and maneuverability. In particular, experiments have shown the ability to operate continuously in a circle one-vehicle length in diameter and the ability to turn in three-quarters of a body length or less. Screw propellers and jet pumps are proven underwater vehicle propulsion methods. These, combined with lifting surfaces and thrusters, provide traditional maneuvering capabilities. They have, however, severe performance limitations when looked at over the range of potentially required speed capability and maneuverability for a number of future missions. The strength of VC propulsion and maneuvering lies in exactly these areas of weakness: operations in surf and very shallow water zones or in high current gradients, demanding the ability to exert virtually instantaneous high maneuvering forces in any direction. Such capabilities will enable in-shore surveillance, reconnaissance, and other covert missions that cannot now be accomplished, and expand the reach of submarines into areas that make them a truly asymmetric threat.

Subjects: VORTICITY CONTROL UNMANNED UNDERSEA VEHICLE (VCUUV), ASYMMETRY, VORTICITY CONTROL PROPULSION, MANEUVERABILITY

Anderson, J.M.; Kerrebrock, P.A.

The Vorticity Control Unmanned Undersea Vehicle (VCUUV) Performance Results

International Symposium on Unmanned Untethered Submersible Technology. 11th. Held in Durham, NH, 08/23/1999 to 08/25/1999. Sponsored by: AUSI. (Draper Report no. P-3747)

Abstract: The Vorticity Control Unmanned Undersea Vehicle (VCUUV) at Draper Laboratory is the first mission-scale, autonomous underwater vehicle that uses vorticity control propulsion and maneuvering. The VCUUV is a self-contained free-swimming research vehicle, that follows the morphology and swimming motion of a yellowfin tuna. A rigid pressure hull comprises the forward half of the vehicle, which houses batteries, electronics, ballast, and a hydraulic power unit. The aft section is a freely-flooded articulated robot tail that is terminated with a lunate caudal fin. Utilizing tail kinematic data from the MIT Robotuna, the VCUUV has demonstrated stable steady swimming up to 2.4 kn and aggressive maneuvering trajectories with turning rates up to 75 deg/s. This paper summarizes the vehicle integration, field experiments, and performance results of this novel vehicle propulsion study.

Subjects: VORTICITY CONTROL UNMANNED UNDERSEA VEHICLE (VCUUV), AUTONOMOUS UNDERWATER VEHICLES, UNDERWATER PROPULSION

Anszperger, J.; Silver, L.; Satlow, F.; Hermanson, J.

Testing Environment for the GPS Space and Control Segments

Joint Services Data Exchange (JSDE). Held in Norfolk, VA, 11/15/1999 to 11/19/1999. (Draper Report no. P-3784)

Abstract: The GPS satellite constellation is controlled by ground-based facilities collectively known as the Operational Control Segment (OCS) (Figure 1). The OCS includes a central Master Control Station (MCS) located at Schriever APB, CO, a backup MCS (BUMCS) located in Gaithersburg, MD, and a number of geographically dispersed Ground Antennas (GAs) and Monitor Stations (MSs), also known as ground stations or remote sites. This paper describes the Telecommunication Simulator Test Station (TSTS), a relatively new facility located at Cape Canaveral Air Station (CCAS), Florida. The purpose of the TSTS is to provide a high-fidelity testing environment for new GPS satellite and OCS software releases, a facility for checkout of production satellites prior to launch, and testbeds for GA and MS hardware releases.

Subjects: GLOBAL POSITIONING SYSTEM (GPS), TELECOMMUNICATION SIMULATOR TEST STATION (TSTS)

Barton, G.H.; Tragesser, S.G.

Autonomous Intact Abort System for the X-34

Atmospheric Flight Mechanics. Held in Portland, OR, 08/09/1999-08/11/1999. Sponsored by: AIAA. (Draper Report no. P-3759)

Abstract: Autonomous algorithms are developed that provide trajectory guidance for horizontally landing vehicles such as the X-34 under a variety of abort conditions. The nominal guidance system of the X-34 is incapable of directing the vehicle to a safe landing for many possible situations in which trajectory is far away from nominal conditions (as in the case of an engine failure). To minimize the risk of losing the vehicle, the autonomous intact abort system considers multiple landing sites and redesigns certain guidance inputs in order to adapt to the new conditions presented by the abort. The abort system design is demonstrated in a high-fidelity simulation to prove the feasibility of the concept for various engine-out scenarios. These abort algorithms are being incorporated into the X-34 vehicle to flight test this new technology as a part of the Future-X Pathfinder Flight Demonstration Program.

Subject: X-34, ALGORITHMS, ABORT GUIDANCE, TRAJECTORY CONTROL

Barton, G.H.; Tragesser, S.G.

Autolanding Trajectory Design for the X-34

Atmospheric Flight Mechanics. Held in Portland, OR, 08/09/1999 to 08/11/99Sponsored by: AIAA. (Draper Report no. P-3758)

Abstract: An Autolanding I-load Program (ALIP) is developed to design unpowered autolanding trajectories for the X-34 Mach 8 vehicle. The trajectory comprises geometric flight segments that are based on the Shuttle approach and landing design (steep glideslope, circular flare, and exponential flare to shallow glideslope). Enforcing physical constraints such as loads, vertical descent rate, continuity, and smoothness reduces the design problem to a two-point boundary value problem with conditions on the initial and final dynamic pressure. Finding a solution required the development of trajectory simulation techniques that constrained the flight profile to a prescribed geometry. The design methodology can be extended beyond the autolanding flight regime by repeating the series of geometric segments and solving multiple two-point boundary values problems (one for each series). The techniques described in this paper facilitate the rapid design of reference trajectories.

Subject: X-34, TRAJECTORIES, AUTOLANDING I-LOAD PROGRAM (ALIP), TRAJECTORY SIMULATION

Bedrossian, N.S.; McCants, E.

Space Station Attitude Control during Payload Operations

Astrodynamics Specialist Conference. Held in Anchorage, AK, 08/16/1999 to 08/19/1999, pp. 1083-1094. Sponsored by: AAS/AIAA. (Draper Report no. P-3778)

Abstract: Evaluating the feasibility of planned robotic operations requires an analysis methodology and tools that can quickly assess proposed attitude control strategies. In this paper, an efficient approach to model the attitude dynamics of the Space Station during payload motion is presented. This formulation was then used to develop momentum optimal attitude command trajectories for the Space Station control moment gyroscope (CMG) attitude hold controller for use during robotic payload operations. This methodology was applied to a realistic Space Station assembly operation and compared with other alternatives. The results indicate that the optimized attitude command trajectory results in the smallest peak CMG momentum cost.

Subjects: INTERNATIONAL SPACE STATION (ISS), ATTITUDE CONTROL, SPACE STATION PAYLOADS, REMOTE MANIPULATOR SYSTEM (RMS), CONTROL MOMENT GYROSCOPES (CMG)

Bernstein, J.; Bottari, J.; Kirkos, G.

Advanced MEMS Ferroelectric Ultrasound 2D Arrays

IEEE Ultrasonics Symposium, 10/17/1999 to 10/21/1999 Sponsored by: IEEE. (Draper Report no. P-3769)

Abstract: This paper discusses the design of advanced micromachined ferroelectric ultrasound transducers for use at 3 MHz. 16 x 16 arrays of resonant monomorph sensors have been constructed with sol-gel lead zirconate titanate (PZT) as the active ferroelectric layer deposited on insulating layers of ZrO2 and SiO2. A novel in-plane polarization of the PZT is used to maximize sensitivity, while trading off reduced output capacitance to match the CMOS buffer electronics. This results in about 30 dB-improved sensitivity compared with conventional polarizing across the thickness of the PZT layer. Fluid-filled through wafer holes are used as an acoustic matching network to achieve resonance at both 1 and 3 MHz. A lumped element equivalent circuit model will be presented, as well as finite-element analysis showing frequency response and resonant gain. Performance predictions for projector efficiency and receive response are given. Test results are presented, including transmit response, receive sensitivity, and frequency response.

Subjects: MICROELECTROMECHANICAL SYSTEM (MEMS), FERROELECTRIC DEVICES, ULTRASOUND IMAGES

Bernstein, J.J.; Xu, B.M.; Ye, Y.H.; Cross, L.E.; Miller, R.

Dielectric Hysteresis from Transverse Electric Fields in Lead Zirconate Titanate Thin Films

Applied Physics Letters, Vol. 74, No. 23, 06/07/1999, pp. 3549-3551. (Draper Report no. P-3717)

Abstract: Excellent symmetric dielectric hysteresis is observed from lead zirconate titanate (PZT) thin films using transverse electric fields driven by interdigitated surface electrodes. The 1-micron-thick PZT films with a Zr/Ti ratio of 52/48 are prepared on ZrO2 buffered, 4-in-diameter silicon wafers with a thermally grown SiO2 layer. Both the ZrO2 buffer layer and PZT film are deposited by using a similar sol-gel processing. Remnant polarization of about 20 micro-C/cm2 with coercive field less than 40 kV/cm is obtained as measured using a triangle wave at 50 Hz. Thicker films are being developed, and retention for the transversely polarized state is currently under study. One of the objectives of this study is to develop a large array of d33-driven unimorph-sensing elements for a high-resolution acoustic imaging system.

Subjects: LEAD ZIRCONATE TITANATE (PZT), THIN FILMS, HYSTERESIS, ELECTRIC FIELDS, ACOUSTIC IMAGING

Bernstein, J.; Miller, R.; Kelley, W.; Ward, P.

Low-Noise MEMS Vibration Sensor for Geophysical Applications

Journal of Microelectromechanical Systems, Vol. 8, No. 4, 12/1999, pp. 433-438. (Draper Report no. P-3648-REV-A)

Abstract: The need exists for high-sensitivity, low-noise vibration sensors for various applications such as geophysical data collection, tracking vehicles, intrusion detectors, and underwater pressure gradient detection. In general, these sensors differ from classical accelerometers in that they require no dc response, but must have a very low noise floor over a required bandwidth. Theory indicates a capacitive micromachined silicon vibration sensor can have a noise floor on the order of 100 ng/ over a 1-kHz bandwidth while reducing size and weight tenfold compared with existing magnetic geophones. With early prototypes, we have demonstrated a Brownian-limited noise floor at 1.0 g/, orders of magnitude more sensitive than surface micromachined devices such as the industry standard ADXL05.

Subjects: CAPACITIVE SENSORS, SEMICONDUCTORS, GEOPHYSICAL FACTORS, MICROSENSORS, NOISE, SILICON, VIBRATION MEASUREMENT, BROWNIAN NOISE

Boccuzzi, R.; Brown, T.; Cook, B.; Dodds, L.; Kochocki, J.; LeBlanc, M.; Robillard, M.; Stadelmann, E.; Stewart, W.; O'Brien, W.; Hudson, P.; Bracewell, T.; Farmer, K.; Gaborno, N.; Kono, K.; Vassar, E.

A Simulation-Based Test and Evaluation Capability

Institute of Navigation National Technical Meeting. Held in San Diego, CA, 01/25/1999 to 01/27/1999, pp. 567-562.  (Draper Report no. P-3699)

Abstract: SiBaTEC, a Simulation-Based Test and Evaluation Capability, provides a user with the ability to perform real-time hardware-in-the-loop (HIL) simulations. For a system under investigation, SiBaTEC permits design verification, testing of potential components, and subsystem modifications before commitment to a prototype, and testing of modified prototypes in simulation. Furthermore, SiBaTEC provides a means of performing system surveillance through repeatable monitoring and margin testing of hardware and embedded software and hypothesis testing of potential aging and wear-out phenomena. SiBaTEC accomplishes these activities by means of a real-time simulation host supported by a network-based suite of tools, and custom input/output (I/O) capabilities. This paper describes these capabilities of SiBaTEC as well as the current system integration testing on a MK6 guidance system.

Subjects: SIMULATION-BASED TEST AND EVALUATION CAPABILITY (SIBaTEC), HARDWARE IN THE LOOP (HIL), MODELS (SIMULATIONS), DESIGN ENGINEERING, PROTOTYPES, TESTING AND EVALUATION, TRIDENT MK6

Boelitz, F.W.

Kistler Launch Assist Platform (LAP) Return Burn Control

Guidance, Navigation, and Control Conference. Held in Portland, OR, 08/09/1999 to 08/11/1999, pp.1289-1299. Sponsored by: AIAA. (Draper Report no. P-3740)

Abstract: The thrust vector control (TVC) design for the Return Burn segment of the Kistler K-1 Launch Assist Platform (LAP) is presented. The design features a two-mode controller that initially provides state-dependent preignition orientation of the rocket engine, and upon ignition, rapid orientation of the vehicle x-axis back toward the launch zone. Following this pitch reversal, the controller seamlessly switches to a second mode that features integral control with acceleration direction estimation. This second mode provides the fine pointing required by guidance to ballistically loft the LAP back to the launch zone. Control gains for the design are precomputed prior to launch through an automated design procedure that searches over a broad family of gains. The automated design tool simultaneously applies frequency domain and time domain constraints, which results in a controller that achieves stable response with adequate margin and minimal settling time.

Subjects: THRUST VECTOR CONTROL SYSTEMS, KISTLER K-1 VEHICLE, LAUNCH
ASSIST PLATFORM (LAP)

Borenstein, J.T.; Gerrish, N.D.; Currie, M.T.; Fitzgerald, E.A.

New Ultrahard Etch-Stop Layer for High-Precision Micromachining

Proceedings of the 1999 12th IEEE International Conference on Microelectromechanical Systems (MEMS) Orlando, FL, 01/17/99 to 01/21/99, pp. 205-210. (Draper Report no. P-3679)

Abstract: In this work, we describe a high-precision fabrication method for silicon micromachining based on a newly developed epitaxial etch stop. This etch stop, composed of a silicon-germanium ally with no boron doping, outperforms traditional boron-doped etch stops in several important and fundamental ways. Etch selectivities in a variety of standard etchants compare favorably with those obtained using high-concentration boron diffused and epitaxial layers. Microstructural analysis of the new etch-stop layer demonstrates a significant reduction in defect density relative to boron-doped counterparts. Tuning-fork gyroscopes built with the new etch-stop show build dimensions comparable to those fabricated with conventional methods. We propose a band structure model for the etch-stop mechanism that mimics the hole-injection phenomenon often invoked for boron doping, and conclude with a brief discussion of the advantages of this new fabrication technology.

Subjects: MICROELECTROMECHANICAL SYSTEM (MEMS), MICROMACHINING, ETCHING, SILICON, ALLOYS, GERMANIUM, ETCH BEHAVIOR, GYROSCOPES

Cantwell, R.H., Ventresca, R.

GPS Continuous Track on a Spinning Vehicle with Multiple Patch Antenna

International Technical Meeting of the Satellite Division of the Institute of Navigation (ION GPS). Held in Nashville, TN, 09/14/1999 to 09/17/1999, Sponsored by: ION (Draper Report no. P-3721)

Abstract: The objective is to use multiple patch antennas to allow visibility to the GPS satellite vehicles for continuous tracking on a spinning platform without going through the acquisition process. Our methodology is to use patch antennas mounted to allow overlapped visibility coverage of the GPS satellite vehicles. An inertial measurement unit (IMU) is used to determine the attitude and position or coverage of each antenna. Ephemeris is
collected from each visible satellite. Using the GPS receiver's position and the positions of the GPS satellite vehicles (SVs), the receiver determines which satellites are in the field of view (FOV) of each antenna. The overlapped coverage allows an SV to be acquired and tracked on two antennas. At this time, we do a direct track handover from the receiver channel whose antenna will be going out of view to another receiver channel using the antenna that has come into view. This eliminates interruption in signal tracking and thereby results in continuous, accurate navigation solutions. This technique has been demonstrated successfully on multiple spinning vehicles.

Subjects: ANTENNAS SPINNING (MOTION), INERTIAL MEASUREMENT UNIT (IMU), SATELLITE VEHICLES (SV), GLOBAL POSITIONING SYSTEM (GPS)

Cefola, P.J.; Nazarenko, A.I.; Yurasov, V.

Refinement of Satellite Ballistic Factors for the Estimation of Atmosphere Density Variations and Improved LEO Orbit Prediction

Space Flight Mechanics Meeting. Held in Breckenridge, CO, 02/07/1999 to 02/10/1999. Sponsored by: AAS/AIAA. (Draper Report no. P-3713)

Abstract: In an earlier work, Prof. Nazarenko discussed an atomosphere density tracking process that operates in parallel to the orbit determination process. This atmosphere density tracking process employs ballistic coefficient data observed over short arcs from multiple satellites. The process includes: (1) a procedure for constructing the density variations that operates on a 2- or 3-h grid, (2) a procedure for estimating the true ballistic coefficients of the employed satellites that operates on a 28- or 56-day interval (1 or 2 monthly solar cycles), and (3) procedure for forecasting the atmosphere density at future times. This paper focuses on the improvement of the algorithm for estimating the true ballistic coefficient of the employed satellites. The main aspect of this improvement consists of applying, for updating the ballistic factors of nonstandard satellites, a linear function of altitude to model the systematic errors. Numerical testing based on simulated data has been undertaken to verify the correctness of the algorithm. The products of the study include a proposal to work with the real data. The possibility of complex utilization of data from both NORAD and the Russian Space Surveillance System is discussed.

Subjects: LOW EARTH ORBIT (LEO), PREDICTIONS, DENSITY MEASUREMENT, BALLISTICS

Chaudhry, A.I.; Thele, J.D.; Kang, D.S.

High-Velocity Teleoperated Rover

Aerospace Defense Sensing Simulation and Controls (AeroSense). 13th. Held in Orlando, FL, 04/05/1999 to 04/09/1999. Sponsored by: SPIE. (Draper Report no. P-3719) 

Abstract: The High-Velocity Teleoperated rover (HVTR) is motivated by a goal to exceed human physical speed with small ground vehicles for operations in an urban environment. A typical small (man-packable) ground vehicle's speed tops out at 1-2 m/s (2-4 mph). Limited speed is attributed to real-time sensing and processing of the external environment. Low speed makes traversing multiple city blocks taxing on the patience of a human operator. Traversing around a block may take 10-20 min. Even with operator assistance, using video does not significantly increase the speed. This is due to the low perspective of the camera view and camera vibration in outdoor setting.

Subjects: HIGH-VELOCITY TELEOPERATED ROVER (HVTR), MICROROVER, UNMANNED VEHICLES, EXPLOSIVE ORDINANCE DISPOSAL (EOD)

Connelly, J.; Kourepenis, A.; Larsen, D.; Marinis, T.F.

Inertial MEMS Development for Space

International Conference on Integrated Micronanotechnology for Space Applications. 2nd. Held in Pasadena, CA, 04/11/1999 to 04/15/1999. (Draper Report no. P-3726)

Abstract: Micromachined silicon inertial sensors offer revolutionary improvements in cost, size, and reliability for guidance, navigation, and control. Inertial sensors represent an important segment of an emerging microelectromechanical systems (MEMS) technology, which combines semiconductor materials and processing to create integrated mechanical and electrical systems. Batch manufacturing techniques produce thousands of virtually identical MEMS devices, each a few square millimeters in size, enabling enabling inertial systems at a fraction of the cost, size, and power of any previous technology. Development of MEMS inertial instruments is driven by the high-volume, commercial market that targets modest performance applications at prices below $20 per axis. However, Draper Laboratory has developed higher-performance, multi-axis systems using commercial processes to ensure availability and affordability for lower-volume military and space applications. The performance of these new MEMS inertial systems is quickly approaching bias stability of 1 deg/h and scale-factor stability of 100 ppm over -40°C to +85°C. Radiation testing is now underway to evaluate response to predicted space environments. Future MEMS inertial systems will reflect a radical departure from the ways they have been conceived, fabricated, and tested in the past. New inertial devices have been incorporated enabling multi-axis measurement in a planar array and development is underway on a new wafer-scale process integrating sensors and application-specific integrated circuits (ASICs) to create complete systems on a chip. These higher performances, lower power, inertial microsystems will be ideally suited for many spaces applications. This paper addresses Draper's inertial MEMS designs, fabrication methods, instrument and performance progression, and development activities related to space applications. Space radiation issues for MEMS are discussed, expected environments are identified, and radiation testing of MEMS instruments is described. In addition, MEMS packaging development toward high-level multi-axis system integration is reviewed.

Subjects: MICROELECTROMECHANICAL SYSTEM (MEMS); INERTIAL SENSORS; GUIDANCE, NAVIGATION, AND CONTROL (GN&C); APPLICATION-SPECIFIC INTEGRATED CIRCUITS (ASIC)

Cunningham, B.T.; Regan, R.; Clapp, C.; Hildebrant, E.; Weinberg, M.; Williams, J.

Miniature Silicon Electronic Biological Assay Chip and Applications for Rapid Battlefield Diagnostics

Battlefield Biomedical Technologies. Held in Orlando, FL, 04/06/1999, pp. 26-34. Sponsored by: SPIE.

Aerospace Defense Sensing Simulation and Controls (AeroSense). 13th. Held in Orlando, FL, 04/05/1999 to 04/09/1999. Sponsored by: SPIE. (Draper Report no. P-3718)

Abstract: Assessing the medical condition of battlefield personnel requires the development of rapid, portable biological diagnostic assays for a wide variety of antigens and enzymes. Ideally, such a assay would be inexpensive, small, and require no added reagents while maintaining the sensitivity and accuracy of laboratory-based assays. In this work, a Microelectromechanical System (MEMS)-based biological assay sensor is presented that is expected to meet the above requirements. The sensor is a thin silicon membrane resonator (SMR) that registers a decrease in resonant frequency when mass is absorbed onto its surface. By coating the sensor surface with a monolayer of antibody, for example, we have detected the corresponding antigen with a detection resolution of 0.25 ng/ml in phosphate buffer solution. Micromachining techniques are being used to integrate many (64 elements on the first test chip) identical SMR sensors into a single silicon chip, which would be capable of simultaneously performing a wide variety of biomedical assays. The sensors require only a small printed circuit board and 8-V power supply to operate and provide a readout. This presentation will describe the operation of the SMR sensor, the fabrication of the sensor array, and initial test results using commercially-available animal immunoglobulins in laboratory-prepared test solutions.

Subjects: MICROELECTROMECHANICAL SYSTEM (MEMS), BIOSENSORS, IMMUNOASSAYS, BIOCHIPS, BATTLEFIELDS

Draim, J.E.; Cefola, P.; Proulx, R.; Larsen, D.; Granholm, G.R.

Elliptical Sun-Synchronous Orbits with Line of Apsides Lying In or Near the Equatorial Plane

Astrodynamics Specialist Conference. Held in Anchorage, AK, 8/16/1999 to 8/19/1999, pp. 183-205. Sponsored by: AAS/AIAA. (Draper Report no. P-3755)

Abstract: This paper explores the characteristics of retrograde, sun-synchronous elliptic orbits with line of apsides lying in or near the equatorial plane. Coverage plots for a five-satellite ring showing the number of satellites in view and elevation angle data versus latitude and local time are presented. Stability of the orbit is discussed. Also analyzed is the effect of the trapped radiation field environment (Van Allen Belts) on these orbits, as well as the exposure to damage by natural and man-made debris. A major advantage seen for these orbits is that they can be used to provide augmented earth coverage for a selected latitudinal zone and a selected time of day (for all longitudes). This feature should prove useful for nongeostationary satellite communications systems where increased capacity is needed during daytime peak-traffic hours in heavily populated latitude bands.

Subjects: ELLIPSO SATELLITES, SUN-SYNCHRONOUS ORBITS, APSIDES, EQUATORIAL ORBITS, ELLIPTICAL ORBITS

D'Souza, C.; Bogner, A.J.; Brand, T.; Tsukui, J.; Koyama, H.; Nakamura, T.

An Evaluation of the GPS Relative Navigation System for ETS-VII and HTV

AAS Guidance and Control Conference. 22nd. Held in Breckenridge, CO, 02/03/1999 to 02/07/1999. Sponsored by: AAS. (Draper Report no.P-3711)

Abstract: The Global Positioning Satellite (GPS) system is increasingly being used for spacecraft navigation. Not only is GPS being used in the traditional role of absolute navigation, but it is also playing a role in relative navigation, particularly for spacecraft rendezvous. Two such instances in which relative GPS navigation is playing a key role in spacecraft rendezvous are the Engineering Test Satellite 7 (ETS-VII) and the HII Transfer Vehicle (HTV). ETS-VII is a test satellite developed by the National Space Development Agency of Japan (NASDA) and is designed to test the performance of a relative GPS system. HTV is the Japanese resupply vehicle for the International Space Station (ISS) and is being developed by NASDA. As currently envisioned for HTV, the ISS will send its GPS measurement information over a radio frequency (RF) link to HTV, which will simultaneously take GPS measurements to the same satellites. The HTV will difference the GPS measurements in a filter to provide highly accurate relative position and velocity information. NASDA has selected relative GPS navigation to be used for the rendezvous from approximately 23 km from the ISS to 500 m, after which a laser sensor will be used to position the visiting vehicle for grappling by an ISS arm. The Charles Stark Draper Laboratory has evaluated the GPS relative navigation system for both ETS-VII and HTV. This paper will describe the testing methodology of the GPS relative navigation system that was used to confirm the tests carried out by Mitsubishi Electric Corporation (MELCO) under contract to NASDA. The testing methodology used by Draper involved the use of an RF satellite signal simulator. In addition to providing a description of the filter architecture, MELSO also provided the trajectory data to drive the satellite signal simulator. A Northern Telecommunications (NorTel) Satellite Signal Simulator (SSS) used the target and chaser vehicle trajectory information to create the RF signal that a GPS receiver would expect to experience along the trajectory. Measurement data, including pseudorange and delta range measurements were recorded from the GPS receiver, with each trajectory being run separately. The recorded data from the two trajectories were then processed in a filter. Proper merging of the measurement data in the relative navigation filter involved the synchronization of data from the two receivers. Only those measurements that were from common satellites were used in the filter. The measurement data from the target and the chaser GPS receiver were time-tagged with slightly different times. Therefore, in order to difference the measurements, they had to be brought to a common time. This was performed using linear interpolation, with the target measurement being the reference time. The filter was an 8-state linearized Kalman filter. The states included the three relative position states, three relative velocity states, a relative clock bias state, and a relative clock drift state. The position and velocity states were expressed in the Hill frame, which is a curvilinear, rotating frame. The filter dynamics for the position and velocity were described by the well-known Hill-Clohessy-Wiltshire equations. An evaluation was also performed as to whether using the position and velocity for the target and the chaser for the propagation would improve the navigation results and it was found to improve the results. However, the Hill-Clohessy-Wiltshire equations, which yield a closed-form state transition matrix (STM), were still used in the propagation of the covariance matrix. With the use of numerical integration for the state equations and the state transition matrix for the propagation of the covariance matrix, excellent filter performance was obtained. The relative position accuracy was better than 0.4 m and the relative velocity accuracy was better than 6 cm/s. During coasting periods of the trajectory, the velocity accuracy was better than 1 cm/s.

Subjects: GLOBAL POSITIONING SYSTEM (GPS); GUIDANCE, NAVIGATION, AND CONTROL (GN&C); SPACECRAFT MOTION; RECEIVERS

Elwell, J.

Inertial Navigation for the Urban Warrior

Digitization of the Battlespace. 4th. Held in Orlando, FL, 04/07/1999 to 04/08/1999, pp. 196-204. Sponsored by: SPIE.(Draper Report no. P-3716)

Abstract: Individual soldier geolocation in situations such as urban warfare where loss of Global Positioning System (GPS) track can impact mission success has become a critical problem. Concepts such as RF "time difference of arrival" and "dead reckoning" techniques have not demonstrated their ability to support navigation reliably inside buildings on their own. Inertial navigation is the only technology that operates independent of external assets. The advent of micromechanical inertial sensor technology has resulted in low-cost, very small, low-power navigation systems capable of fitting in a soldier's boot. A miniature navigator consisting of three micromechanical gyroscope and accelerometer packages, including supporting application-specific integrated circuit chips, and capable of operating in support of such a mission has been developed. However, because of accelerometer and gyroscope drift, navigating inertially over long time periods, using even the most precise and most expensive inertial sensors available today, remains close to impossible. Inertial augmentation techniques are therefore required, and the concept of personal inertial navigation systems aided by zero velocity updating of the accelerometers with each footfall has been examined and shown to be sufficient to determine the location of an individual soldier accurately within a large building complex after hours of operation. In addition to the accelerometer, updates of the gyro via zero attitude rate techniques also enhance position accuracy, as well as provide an attitude reference in support of soldier-carried targeting sensors.

Subjects: URBAN WARFARE, GLOBAL POSITIONING SYSTEM (GPS), INERTIAL NAVIGATION, MINIATURIZATION

Flueckiger, K.; Dowdle, J.

A High Antijam INS GPs Navigator

Association of Old Crows. Held in Adelphi, MD, 04/07/1999 to 04/08/1999. Sponsored by: NAVWAR. (Draper Report No. P-3728)

Abstract: Traditionally, integrated inertial and Global Positioning System (GPS) sensing has been used to provide accurate high-bandwidth navigation solutions. Algorithms designed to integrate these sensors have not used the full sensor data available in a centralized manner. The so-called loosely-coupled integration approach assumes that GPS provides a (low-bandwidth) Position, Velocity, and Time (PVT) solution to the navigation algorithm. Traditionally, tight integration approaches demand that GPS provide pseudorange and delta-range measurements. In contrast, the Deep Integration Algorithm, introduced here, uses raw in-phase and quadrature (I and Q) components from the GPS receiver's correlator outputs. By using this full information from the receiver hardware, analysis and hardware results indicate that the Deep Integration Algorithm will improve GPS jamming immunity significantly. A preliminary implementation of the Deep Integration Algorithm for a single SV has been embedded successfully within a commercial-off-the-shelf C/A receiver. Results indicate that the receiver loss-of-lock threshold can be extended by approximately 15 to 20 dB in a sustained jamming environment. Results from two dynamic scenarios are presented here: (1) a velocity step along the SV line-of-sight, and (2) a tactical munition scenario. Both scenarios are presented under a variety of jamming environments. The results are extrapolated to predict the performance of the Deep Integration Algorithm, with full multi-SV tracking capability, using P(Y)-code receiver hardware. This analysis is consistent with performance predictions based on (software-only) simulation.

Subjects: INERTIAL NAVIGATION SYSTEMS (INS), GLOBAL POSITIONING SYSTEM (GPS), ANTIJAMMING, MILITARY APPLICATIONS, COMMERCIAL APPLICATIONS

Fuhry, D.

Adaptive Atmospheric Reentry Guidance for the Kistler K-1 Orbital Vehicle

Guidance, Navigation, and Control Conference. Held in Portland, OR, 08/09/1999 to 08/11/1999, pp. 1275-1288. Sponsored by: AIAA. (Draper Report no. P-3738)

Abstract: The Kistler K-1 is designed to be a fully-reusable, two-stage launch vehicle for economical delivery of small satellite payloads to low earth orbit. Greatest efficiency and hence lowest cost are achieved by flyback of both vehicle stages to the near vicinity of the launch site. After deploying the payload and performing necessary phasing maneuvers, the second-stage Orbital Vehicle (OV) performs a deorbit burn to achieve the desired trajectory conditions at atmospheric entry. After entering the atmospheric, the OV is steered aerodynamically until reaching the deployment point for a stabilization parachute. Subsequently, drogue and main parachutes complete deceleration of the vehicle for landing on airbags. This paper presents the design of an atmospheric guidance algorithm for bank-to-turn steering of the OV prior to deployment of the stabilization parachute. Reentry guidance targets a desired geographic position for deployment of the drogue parachute. The algorithm employs a numerical predictor/corrector technique to compute the bank angle and the start time of a single bank reversal required to null the predicted target position miss. Aerodynamic loads and heating are limited implicitly by selection of deorbit target conditions for reentry trajectory shaping. Results obtained using the Draper Laboratory K-1 Integrated Vehicle Simulation illustrates guidance performance under nominal and dispersed conditions.

Subjects: KISTLER K-1 VEHICLE, REUSABLE LAUNCH VEHICLES, ALGORITHMS, STEERING, REENTRY GUIDANCE

Granholm, G.R.; Proulz, R.J.; Cefola, P.J.

Orbit Determination for Medium Altitude Orbits Using GPS Receivers and Ground-Based Tracking

Astrodynamics Specialist Conference. Held in Anchorage, AK, 08/16/1999 to 08/19/1999, pp. 401-420. Sponsored by: AAS/AIAA. (Draper Report no. 3760)

Abstract: The past few years have seen a proliferation of nontraditional medium or high-altitude constellations designed for use in communications. A constellation considered for use in the Ellipso system features 10 satellites in highly elliptical sun-synchronous frozen line of apsides (SSFLA) orbits. These orbits pose unique challenges to the orbit determination process, including high eccentricity, tesseral resonance, critical inclination, and sensitivity to solar radiation pressure. This paper will compare the effectiveness of GPS-based tracking with ground-based tracking in terms of accuracy of differential correction (DC) solutions. A "Truth" orbit will be simulated using a high-precision Cowell numerical integrator. This orbit is then used to create simulated GPS pseudoranges and ground-based Doppler range and range-rate measurements. The GPS constellation is modeled and propagated using analytic J2-only equations expressed in equinoctial elements. To improve speed and performance, the GPS simulation is coded using a message-passing interface (MPI) parallel implementation. The pseudoranges and range/range-rate observations are used in a least-square DC process to solve for state parameters, solar radiation and drag coefficients, and ground station biases. Differences between the touch and fit/predict orbits are analyzed numerically and graphically. Cases are run for both atmospherically quiet and perturbed epochs and with atmospheric and gravitational mismodeling. It is found that the accuracy of the solution is strongly affected by atmospheric conditions. Both methods yield similar solutions, but the dc process scan requires more ground-based observations than GPS pseudoranges. Overall, both tracking methods are shown to be viable for these types of orbits.

Subjects: ORBIT DETERMINATION, ORBITAL ALTITUDE, GPS RECEIVER INTERFACE PROCESSOR (GRIPS), GROUND-BASED SURVEILLANCE AND TRACKING SYSTEM (GSTS), ELLIPSO SATELLITES, APSIDES

Guinon, W.; Setterlund, R.H.; Phillips, R.

Reducing the Power Requirements of an Interferometric GPS Receiver for Spacecraft Attitude Determination

Vision 2010: Present and Future: National Technical Meeting. Held in San Diego, CA, 01/25/1999 to 01/27/1999, pp. 561-573. Sponsored by: ION. (Draper Report no. P-3706)

Abstract: The ongoing development of micromechanical inertial systems that require very little power suggests the concomitant development of a low-power GPS receiver. The combination of such an interferometric receiver with inertial instruments would fill the need for a low-cost, lightweight, low-power attitude determination system for use in small, low-cost satellites with modest accuracy requirements (0.1 to 0.5 deg.). Power consumption by the GPS receiver can be reduced by turning off the RF front end, the frequency synthesizer, the reference oscillator and the digitizer for brief intervals of time while using the inertial system to maintain adequate attitude knowledge and to simplify obtaining subsequent IGPS attitude updates without time-consuming integer ambiguity resolution. This study looks at the implications of this strategy on the details of the receiver operation and design, including reacquisition, and the trade between pre- and post-detection integration, as well as power consumption. The accuracy of such a system as a function of the interval between GPS measurements was assessed. Depending on this interval and on other parameters such as inertial measurement unit (IMU) quality, antenna baseline, etc., system power consumption on the order of 1 W or less can be achieved. Accuracies in the 0.1- to 0.5-deg regime are readily achievable. Volume, weight, and power projections are based on existing technology and hardware, leading to a system concept for a spacecraft attitude determination that could be of enormous benefit for small satellites.

Subjects: GLOBAL POSITIONING SYSTEM (GPS), RECEIVERS, SPACECRAFT, ATTITUDE DETERMINATION, POWER REQUIREMENTS

Hall, W.D.; Odoni, A.R.

A New Airport Capacity Allocation Method and Its Simulation Through Optimization

Date: 9/28/1999. (Draper Report no. P-3764)

Abstract: This paper describes the Arrival-Departure Capacity Allocation Method (ADCAM), a new approach to airport capacity allocation that accounts for airport arrival capacity, departure capacity, and the interactions between arrivals and departures. ADCAM provides the users of the Air Transportation System with additional flexibility during periods when airport capacity is insufficient to serve demand without delay, and it improves the ability of the airlines and air traffic management to predict and manage the outcome of such situations. Implementation of new procedures in the air transportation system is an expensive endeavor. This expense must be justified by tangible benefits, which can be difficult to determine analytically before the procedure change has been implemented. Indeed, even after a procedural change, it is extremely difficult to assess its impact because of the lack of controlled experimental conditions. The benefit of the arrival-departure capacity allocation method is assessed here through simulation. A unique feature of the simulation is that optimization is used to model the response of an airline to air traffic flow management. The simulation is able to assess not only traditional measures of system performance such as airport throughput and passenger-minutes of delay, it also measures the value to the airlines of their realized plans. Using the simulation, one can compare the airlines' optimal solutions under ADCAM to those under the current method of allocating airport capacity, answering the question: "How much better could the airlines operate under ADCAM?" The simulation results suggest that operations under ADCAM would be more predictable than they are today, that the airlines could save considerable amounts of money, that airline service would improve, that fuel would be saved and hazardous emissions reduced.

Subjects: AIRPORT CAPACITY, ARRIVAL-DEPARTURE CAPACITY ALLOCATION METHOD (ADCAM), OPTIMIZATION, MODELS (SIMULATIONS)

Hammett, R.

Fault-Tolerant I/O Networks Applied to Ship Control

Ship Control Systems Symposium. 12th. Held in The Hague, Netherlands, 10/19/1999 to 10/21/1999. Sponsored by: SCS. (Draper Report no. P-3741)

Abstract: Future ships will require sophisticated onboard control systems to control machinery, automate tasks, optimize subsystem performance, and simplify maintenance. These controls will exploit the availability of inexpensive computer processing, will use many sensors and actuation devices, and will provide for completely integrated and coordinated control of all subsystems. The crew's increased reliance on these automated functions makes it essential that they provide dependable operation despite equipment failure or battle damage, e.g., they must be fault tolerant and damage survivable. An example of such a system is the U.S. Navy Seawolf submarine ship control. But the redundant sensors and actuation system used on Seawolf, with their associated electronics and wiring, must be made more compact and affordable for the approach to find widespread use on future ships. This paper describes how the use of data buses, intelligent sensors, and fault-masking actuation electronics can be used to construct input/output (I/O) networks that provide flexibility and growth, and that are highly dependable, affordable, and easily installed. These I/O networks can make widespread use of fault- and damage-tolerant systems practical. The use of I/O networks complements other efforts to make greater use of electrical actuation aboard ships. This paper explores the requirements for such systems and examines some of the technology trade-off that must be made, such as network media type (i.e., optical fiber, wired, or wireless), power distribution to network electronics, network topology (ring or bus), network size vs. speed, distributed vs. centralized I/O processing, and cross connections between I/O channels. The paper concludes by describing a concept for a fault-tolerant network I/O system and discussing the steps needed to develop such systems for future ships.

Subjects: FAULT-TOLERANT PROCESSORS, INPUT/OUTPUT PROCESSING, SHIP CONTROL SYSTEMS, SEAWOLF SHIP CONTROL SYSTEM

Hammett, R.C.

Ultrareliable Real-Time Control Systems-Future Trends

IEEE Aerospace and Electronic Systems Magazine, Vol.14, No. 8, 08/1999, pp. 31-6. (Draper Report No. CSDL-99-008-REV-A)

Abstract: Today's aircraft use ultrareliable real-time controls for demanding functions such as Fly-By-Wire (FBW) flight control. Future aircraft, spacecraft, and other vehicles will require greater use of these types of controls for functions that currently are allowed to fail, fail to degraded operation, or require human intervention in response to failure. Fully automated and autonomous functions will require ultrareliable control. But ultrareliable systems are very expensive to design and require large amounts of onboard equipment. This paper will discuss how the use of low-cost sensors with digital outputs, digitally commanded fault-tolerant actuation devices, and interconnecting networks of low-cost data buses offer the promise of more affordable ultrareliable systems. Specific technologies and concepts to be discussed include low-cost automotive and industrial data buses, "smart" actuation devices with integral fault masking capabilities, management of redundant sensors, and the fault detection and diagnosis of the data network. The advantages of integrating the control and distribution of electrical power with the control system will be illustrated. The design, installation, and upgrade flexibility benefits provided by an all-digital and shared network approach will be presented. The economic benefits of systems that can operate following failure and without immediate repair will be reviewed. The inherent ability of these redundant systems to provide effective built-in test and self-diagnostics capabilities will be described. The challenges associated with developing ultrareliable software for these systems and the difficulties associated with exhaustive verification testing will be presented as will additional development hurdles that must be overcome.

Subjects: AVIONICS, CONTROL SYSTEMS, REAL-TIME SYSTEMS, FAULT-TOLERANT COMPUTERS, SENSORS, ACTUATORS, COMPUTER SOFTWARE, SELF-TESTS, COST-EFFECTIVENESS, ULTRARELIABLE REAL-TIME SYSTEMS

Hattis, P.; Bailey, R.

Overview of the Kistler K-1 Guidance & Control System

Guidance, Navigation, and Control Conference. Held in Portland, OR, 08/09/1999 to 08/11/1999, pp. 1247-1254. Sponsored by: AIAA. (Draper Report no. P-3735)

Abstract: Draper Laboratory, under contract to Kistler Aerospace Corporation, is developing the complete flight guidance and control software for the K-1 launch vehicle. The K-1 is a fully reusable two-stage vehicle. The entire K-1 flight is performed autonomously except for one uplink of expected landing site winds before landing. The Launch Assist Platform (LAP) first stage flies a nearly open-loop three NK-33 engine boost phase, and subsequently reignites the center engine after staging to enable return to the launch site in a controlled coasting flight. The Orbital Vehicle (OV) second stage uses a single NK-43 engine to fly a fully closed-loop ascent to orbit. The LAP trajectory is designed to trade return propellant requirements against OV ascent performance impacts. Orbital maneuvers that are computed onboard the OV are used to circularize its orbit, deploy the payload, rephase the OV orbit for landing after 24 h, and then deorbit the vehicle. The OV reentry is flown with control thrusters used to bank the vehicle as directed by a predictor-corrector guidance law. Landing of both stages is done with a parachute descent and airbag touchdown, with return trajectories biased to provide correction of expected parachute wind drift effects during descent.

Subjects: KISTLER K-1 VEHICLE, GUIDANCE AND CONTROL, LAUNCH VEHICLES, LAUNCH ASSIST PLATFORM (LAP), ORBITAL VEHICLES

Henderson, T.; Dennehy, N.

Attitude Control and Energy Storage (ACES) Flywheel Demonstration Testbed

Space Power Workshop. 17th. Held in Long Beach, CA, 04/19/1999 to 04/21/1999. (Draper Report no. P-3730)

Subjects: FLYWHEELS, ATTITUDE CONTROL AND ENERGY STORAGE (ACES), ROTORS, TESTBEDS

Houston, K.M.; Hillman, R.E.; Kobler, J.B.; Meltzner, G.S.

Development of Sound Source Components for a New Electrolarynx Speech Prosthesis

International Conference on Acoustics, Speech, and Signal Processing (ICASSP). 24th. Held in Phoenix, AZ, 03/15/1999 to 03/19/1999. Sponsored by: IEEE. (Draper Report no. P-3690)

Abstract: For many individuals who lose their voices due to laryngeal cancer or trauma, the only option for speech is to use an electrolarynx (EL), which is a battery-powered vibrator that is held to the throat. Current devices produce speech that is very machine-like in sound with low levels of loudness and intelligibility that also draws undesired attention to the user. A project at Draper Laboratory, the Mass. Eye and Ear Infirmary, and MIT aims to develop a much improved EL called the Electrolarynx Communication System (ELCS), which is a DSP-based device consisting of a sound source, control, and speech enhancement subsystems or modules. This paper introduces the ELCS and discusses developments to date in the sound source module. Specific topics include the design of a new linear EL transducer and investigations into glottal waveform synthesis that should result in much more nature speech output.

Subjects: SPEECH PROCESSING, SYNTHETIC SPEECH, PROSTHESIS, ELECTROLARYNX, COMMUNICATION SYSTEMS, SPEECH ARTICULATION

Kirkos, G.; Bernstein, J.J.; Miller, R.; Finberg, S.; Houston, K.; Xu, B.; Ye, Y.; Cross, L.E.

Design of Micromachined PZT-on-Silicon 3-MHz Ultrasound Transducer Arrays (Abstract Only)

U.S. Navy Workshop on Acoustic Transduction Materials and Devices, 1999. (Draper Report no. P-3715)

Abstract: The DARPA-funded Sonoelectronics program is developing a hand-held underwater 3-D camera for high-resolution imaging through murky water. Draper is teamed with Lockheed Martin IRIS and Stanford University to create the sonar system. Potential commercial applications include medical ultrasound, fish identification, and nondestructive testing (NDT). This talk will discuss the design of micromachined ultrasound transducers for use at 3 MHz. A monomorph structure is constructed on resonant diaphragms, with sol-gel lead zirconate titanate (PZT) as the active ferroelectric layer deposited on insulating layers of ZrO2, SiO2, and undoped polysilicon. A novel in-plane polarization of the PZT is used to maximize sensitivity, while trading off output capacitance to match the CMOS buffer electronics. This results in 30-dB improved sensitivity compared with conventional polarizing across the thickness of the PZT. Fluid-filled through wafer holes (etched using deep inductively coupled plasma (ICP) etching) are used as an acoustic matching network to achieve resonance at both 1 and 3 MHz. A lumped-element equivalent circuit model will be presented, as well as finite-element analysis showing frequency response and resonant gain. Performance predictions for projector efficiency are based on FEA analysis, while receive sensitivity is derived from transmit response using reciprocity relations. Arrays of 16 x 16 elements are being fabricated currently. In Phase 2, 32 x 64 element arrays will be tiled into 128 x 128 retina arrays. Predicted receive sensitivity is -207 dB ref. 1 V/mPa at 3 MHz, while transmit response is predicted to be 115 dB ref. 1 mPa/V @ 1 m.

Subjects: ULTRASOUND IMAGES, LEAD ZIRCONATE TITANATE (PZT), TRANSDUCERS

Kogan, R.G.; Desai, M.; Pien, H.; Grimson, E.

Model-Based Visualization of Ultrasound Images

Battlefield Biomedical Technologies. Held in Orlando, FL, 04/06/1999, pp. 84-92. Sponsored by: SPIE.(Draper Report no. P-3725)

Abstract: Ultrasound imaging is the most pervasive, cost-effective, portable, high-resolution, and non-ionizing modality of diagnostic imaging available. The use of ultrasounds, however, has been hampered by the noise properties and poor contrast inherent in such imagery. A novel processing system is currently being developed that overcomes some of these disadvantages by producing a high-quality rendering of the anatomical structure of interest. In particular, a normal anatomical atlas is used as the starting point; this atlas is produced from either CT or MR imagery. As the ultrasound probe is moved along the body, image registration techniques, as well as external instrumentation that monitors the position and attitude of the ultrasound probe, are used to provide a continuous mapping between the ultrasound observations and the atlas. As discrepancies between the atlas and the observed anatomy occur, the atlas is deformed to reflect actual observations. Operated in this mode, the system displays the deformed high-resolution atlas to the user, providing a high-contrast, low-noise rendering of the patient's anatomy. In scenarios such as battlefield critical care, where large, immobile CT or MR scanners are not feasible, deformation of a high-quality atlas to match real-time ultrasound imagery can provide for much improved assessment and treatment possibilities.

Subjects: ULTRASOUND IMAGES, ANATOMY, IMAGE PROCESSING, IMAGE REGISTRATION

Kourepenis, A.

Low-Cost MEMS Inertial Systems for GPS Antijam Applications

Date: 4/8/1999. (Draper Report no. P-3729)

Abstract: Microelectromechanical Systems (MEMS) technologies have the enormous potential to enable the realization of low-cost inertial systems for a myriad of both commercial and military applications. With the large volume needs of the commercial market seeking inertial systems for automotive, camcorder, toys, and other applications, an economical base for the low-cost manufacture of these technologies will be established. These same capabilities can be leveraged to realize low-cost inertial systems critical to the development and deployment of weapons platforms at costs unable to be matched in other technologies. Current applications being demonstrated with MEMS inertial technologies include competent munitions, autonomous vehicles, robotics, and personal navigation. Many of these applications use MEMS-based Inertial Navigation System/Global Positioning Systems (INS/GPS) to enable precise guidance, na