Abramson, M. et al.

Abramson, M. et al.

Abramson, M. et al.

Abramson, M. et al.

Allinger, D.F. et al.

Allred, C.L. et al.

Anderson, J.A. et al.

Aron, E.C. et al.

Barbour, N.M.

Barbour, N.M. et al.

Barbour, N.M.

Barrows, T.M.

Barton, G.H.

Bedrossian, N.S. et al.

Bloom, I.B.K.

Boelitz, F. et al.

Borenstein, J. et al.

Borenstein, J.T. et al.

Connelly, J. et al.

Cunningham, B. et al.

Design, Fabrication, and Vapor Characterization of a Microfabricated Flexural Plate Resonator Sensor and Application to Integrated Sensor Arrays

DiMatteo, R.S. et al.

Eiceman, G.A. et al.

Gupta, N. et al.

STS-99 Shuttle Radar Topography Mission Stability and Control

Hammett, R.

Hammett, R.C.

Hattis, P. et al.

Johnson, W.M. et al.

Johnson, W.M. et al.

Kerrebrock, P.A. et al.

King, K.R. et al.

Kondoleon, C.A. et al.

Kondoleon, C.A. et al.

Kondoleon, C.A. et al.

Laine, J.P. et al.

LeBlanc, J. et al.

Leisk, G.G. et. al.

Miller, R.A. et al.

Moynahan, S.A. et al.

Murphy, M. et al.

Owens, M.M. et al.

Petrovich, A. et al.

Phillips, R. et al.

The Role of Short-Periodic Motion in a Formation Flying of Satellites with Large Differential Area to Mass Ratio

Time-Optimal Reorientation of Asymmetric Rigid Bodies

STS-99 Shuttle Radar Topography Mission Dynamics and Control - Mission Overview

Socha, M. et al.

Tapalian, C. et al.

Wall, C., III; et al.

8th Saint Petersburg International Conference on Integrated Navigation Systems

Date: 5/28/2001 to 5/30/2001. (Draper Report no. CSDL-2001-029)

Subjects: NAVIGATION SYSTEMS, INERTIAL SYSTEMS, INERTIAL SENSORS, INTEGRATED SYSTEMS, SATELLITES

Abramson, M.; Carter, D.; Kolitz, S.; McConnell, J.; Ricard, M.; Sanders, C.

Autonomous Satellite Tasking for Observation of Ephemeral Terrestrial Phenomena

Florida Artificial Intelligence Research Society (FLAIRS) Conference. 14th. Held in Key West, FL, 05/21/2001 to 05/23/2001. Sponsored by: American Association for Artificial Intelligence (AAAI). (Draper Report no. P-3869)

Abstract: We present initial results from algorithms developed for autonomous reconfiguration of Earth observation satellites. This wilI reduce requirements on the human operators of satellites, improve system resource utilization, and provide the capability to dynamically respond to temporal terrestrial phenomena. Our initial system model consists of one satellite, a single point of interest on Earth (e.g., a volcano) with the objective to maximize the number of observations during a fixed time interval. An approach using integer programming and astrodynamics jointly was used to calculate integrated observation and burn plans that maximize the number of observations during the fixed time interval.

Subjects: EARTH OBSERVATION SATELLITE (EOS), AUTONOMY, TASKING

Abramson, M.; Kolitz, S.; McConnell, J.; Sanders, C.

Human-System Integration in Autonomous Satellite Tasking

FLAIRS Conference. 14th. Held in Key West, FL, 05/21/2001 to 05/23/2001. Sponsored by: AAAI. (Draper Report no. P-3870)

Abstract: We describe the design and initial testing of Draper's Earth Phenomena Observing System (EPOS) a simulation testbed for algorithms being developed for autonomous reconfiguration of Earth observation satellites. Specifically, this paper addresses EPOS human-system integration (HSI) issues and their impact on overall system design. An initial version of EPOS was analyzed to determine current levels of system autonomy across a range of potential users, including Earth scientists, system operators, and algorithm developers. Results will be used to help determine the appropriate levels of automation to be employed in future versions of EPOS.

Subjects: EARTH PHENOMENA OBSERVING SYSTEM (EPOS), EARTH OBSERVATION SATELLITE (EOS), AUTONOMY, TASKING, HUMAN COMPUTER INTERACTION (HCI), ALGORITHMS

Abramson, M.; Cleary, M.; Kolitz, S.

Steps Toward Achieving Robust Autonomy

AAAI Spring Symposium. Held in Stanford, CA, 03/26/2001 to 03/28/2001. Sponsored by: AAAI. (Draper Report no. P-3876)

Abstract: We define and describe a robust autonomous system and provide motivating scenarios in which robust autonomy is critical for success. We describe Draper's approach to achieving robust autonomy and successful applications of the approach. Finally, we discuss a number of technical challenges to achieving robust autonomy that we are working on in our current research and development.

Subjects: AUTONOMY, ROBUSTNESS, UNINHABITED COMBAT AIR VEHICLES (UCAV), EMBEDDED COLLABORATIVE INTELLIGENT SYSTEMS (ECIS), EUROPAN SUBMARINE, ADVANCED UNDERWATER VEHICLE (AUV), AUTONOMOUS MINEHUNTING AND MAPPING TECHNOLOGY (AMMT), SMALL AUTONOMOUS AERIAL VEHICLE (DSAAV)

Abramson, M.; Carter, D.; Kolitz, S.; McConnell, J.; Ricard, M.; Sanders, C.

The Design and Implementation of Draper's Earth Phenomena Observing System (EPOS)

Space. Held in Albuquerque, NM, 08/28/2001 to 08/30/2001. Sponsored by: AIAA. (Draper Report no. P-3910)

NASA Earth Science Technology. Held in College Park, MD, 08/28/2001 to 08/30/2001. Sponsored by: NASA. (Draper Report no. P-3910-REV-A)

Abstract: Current Earth observation systems trade coverage and revisit times against the number and measurement sensitivity of satellites and on-board sensors. The coverage and utility of observations these large satellites provide are restricted by their selected orbit, launch time, and bus reliability. To lower development and operations costs, a recently proposed alternative is to develop and launch a large suite of smaller size satellites that perform single-purpose measurements. We present initial results from algorithms developed for autonomous reconfiguration of large numbers of Earth observation satellites made possible in a future world wherein refueling of satellites and/or launching of new satellites is cost effective. The algorithms will reduce requirements on the human operators of such a system of satellites, improve system resource utilization, and provide the capability to dynamically respond to temporal terrestrial phenomena. Our initial system model consists of small numbers of satellites, a single point of interest on Earth (e.g., hurricane) with the objective to maximize the total coverage of the target during a number of orbits. An integrated approach using integer programming, network optimization, and astrodynamics was used to calculate integrated observation and maneuver plans that maximize the total coverage of the target while adhering to fuel constraints.

Subjects: EARTH PHENOMENA OBSERVING SYSTEM (EPOS), ALGORITHMS

Allinger, D.F.; Strauss, C.; Kwon, D.

Applications of Speech Technology to Unmanned Vehicles

Digital Avionics Systems Conference. 20th. Held in Daytona Beach, FL, 10/14/2001 to 10/18/2001, pp. 5B41-5B49. Sponsored by: IEEE. (Draper Report no. P-3914)

Abstract: This paper describes the application of speech technology to the functions of mission planning, command, and control of a Vehicle Control Unit (VCU). The VCU is capable of controlling either an unmanned aerial vehicle or unmanned ground vehicle. Configured as a commercial-off-the-shelf (COTS) laptop with a display screen, track ball, keyboard, and joystick, the VCU must be transported in a suitcase and requires "hands-on" operation at all times. For many mission scenarios in which manual manipulation of data and visual display is impractical, speech may provide the only way to interact with the computer. This paper describes the technical approach taken to configure the VCU with speech technology, enabling the human operator to vocally, dynamically plan a mission.

Subjects: SPEECH TECHNOLOGY, VEHICLE CONTROL UNIT (VCU), UNMANNED AERIAL VEHICLES (UAV), UNMANNED GROUND VEHICLES (UGV)

Allred, C.L.; Borenstein, J.; Hobbs, L.W.

Neutron Irradiation-Induced Dimensional Changes in MEMS Glass Substrates

Materials Research Society (MRS) Symposium. Held in Boston, MA, 11/26/2001 to 11/30/2001. Sponsored by: MRS. (Draper Report no. P-3912)

Abstract: A study is made of radiation-induced expansion/compaction in Pyrex and Hoya SD-2 glasses, which are used as substrates for Microelectromechanical System (MEMS) devices. Glass samples were irradiated with a neutron fluence composed primarily of thermal neutrons, and a flotation technique was employed to measure the resulting density changes in the glass. Transport of ions in matter (TRIM) calculations were performed to relate fast (~1-MeV) neutron atomic displacement damage to that of boron thermal neutron capture events, and measured density changes in the glass samples were thus proportionally attributed to thermal and fast neutron fluences. The trend for strain with thermal neutron fluence (n/cm2) was found to be a linear compaction of -2.8 x 10-20 for Pyrex and -1.0 x 10-21 for Hoya SD-2. For fast neutron fluence, the trend for strain was also linear: -6.1 x 10-21 for Pyrex and -7.9 x 10-22 for Hoya SD-2. The measured radiation-induced compaction of Pyrex is found to agree with that of previous studies. To our knowledge, this work represents the first study of compaction in Hoya SD-2 with neutron fluence. Hoya SD-2 is of considerable importance to MEMS, owing to its close thermal expansivity match to silicon from 25-500°C.

Subjects: SUBSTRATES, GLASS, DIMENSIONAL ANALYSIS, NEUTRON IRRADIATION

Anderson, J.A.; Chhabra, N.K.

Maneuvering and Stability Performance of a Robotic Tuna

Stability and Maneuvering Symposium - SICB Annual Meeting. Held in Chicago, IL, 01/06/2001 to 01/07/2001. Sponsored by: SICB. (Draper Report no. P-3868)

Abstract: The Draper Laboratory Vorticity Control Unmanned Undersea Vehicle (VCUUV) is the first mission-scale, autonomous underwater vehicle that uses vorticity control propulsion and maneuvering. Built as a research platform with which to study the energetics and maneuvering performance of fish-swimming propulsion, the VCUUV is a self-contained, free-swimming research vehicle that follows the morphology and kinematics of a yellowfin tuna. The forward half of the vehicle is composed of a rigid hull that houses batteries, electronics, ballast, and hydraulic power unit. The aft section is a freely flooded articulated robot tail that is terminated with a lunate caudal fin. Utilizing experimentally optimized body and tail kinematics from the MIT RoboTuna, the VCUUV has demonstrated stable steady swimming speeds up to 1.2 m/s and aggressive maneuvering trajectories with turning rates up to 75 deg/s. This paper summarizes the vehicle maneuvering and stability performance observed in field trials and compares the results to predicted performance using theoretical and empirical techniques.

Subjects: VORTICITY CONTROL UNMANNED UNDERSEA VEHICLE (VCUUV)

Anderson, R.S.; Hanson, D.S.; Kourepenis, A.S.

Evolution of Low-Cost MEMS Inertial System Technologies

International Technical Meeting of the Satellite Division of the Institute of Navigation (ION GPS). Held in Salt Lake City, UT, 09/11/2001 to 09/14/2001. Sponsored by: ION. (Draper Report no. P-3951)

Abstract: MEMS continues to mature and enable the realization of many previously unachievable applications. Advanced microfabrication techniques have produced small, low-cost silicon inertial sensors of high performance, ruggedness, and inherent symmetry that have been evaluated in automotive antiskid and traction control systems and in advanced guided munitions development programs. Continued advances in both the inertial sensor, application-specific integrated circuit (ASIC) electronics and packaging technologies are required to realize low-cost inertial measurement units (IMU) for applications ranging from gun-launched guided munitions, guided missiles, personnel navigation, and autonomous vehicles. Additional investment is also required in GPS receiver packaging technology to realize an integrated MEMS/GPS IMU that meets the overall performance, size, and cost goals of these applications. Draper Laboratory and the government have invested over $100M developing the pacing technologies to meet these systems needs. These investments will ultimately realize IMUs that are smaller (less than 3 in3), higher performing (1 deg/h and less than 1 mg), and lower in cost (less than $1200/IMU) than is achievable in any competing technology. This paper details the technology roadmap for attaining this end objective, detailing the advances achieved to date, and identifies the future advances required in the sensor, electronics, and packaging arenas. Specific IMU designs and requirements will be presented to better convey the complex demands and applications for this exceptional technology.

Subjects: MICROELECTROMECHANICAL SYSTEM (MEMS), INERTIAL MEASUREMENT UNIT (IMU), APPLICATION-SPECIFIC INTEGRATED CIRCUITS (ASIC), GLOBAL POSITIONING SYSTEM (GPS)

Aron, E.C.; Barton, G.H.; Bottkol, M.S.

RADX-34 - A Future-X Demonstration of Autonomous Robust Abort Technologies on the X-34

Guidance and Control Conference. 24th. Held in Breckenridge, CO, 01/31/2001 to 02/04/2001, pp. 215-232. Sponsored by: American Astronautical Society (AAS). (Draper Report no. P-3867)

Abstract: The Charles Stark Draper Laboratory, Inc. has been conducting the RADX-34 Future-X Pathfinder Flight Demonstration experiment under the direction of the NASA Marshall Space Flight Center. The Future-X experiment will use the X-34 to demonstrate autonomous abort technologies needed for the next generation of reusable launch vehicles. This project will involve integration of real-time abort mission planning algorithms with the existing guidance and control to provide abort coverage for the low-Mach flights of the X-34. This paper describes the design and capability of the abort planner 3 months prior to the conclusion of its development. The mission planner described herein is able to respond to loss of thrust, determine which runways can be reached within the vehicle constraints, and designate an appropriate landing site. This project, when complete, will mark the first step in the development of the Next Generation of Guidance and Control (NGGC) autonomous algorithms. NGGC algorithms will help ensure that the second generation of reusable launch vehicles will meet their cost, safety, and reliability requirements.

Subjects: X-34, FUTURE-X, REUSABLE LAUNCH VEHICLES, ALGORITHMS, NEXT GENERATION OF GUIDANCE AND CONTROL (NGGC)

Barbour, N.M.

Inertial Components - Past, Present, and Future

Guidance, Navigation, and Control Conference. Held in Montreal, Quebec, Canada, 08/06/2001 to 08/09/2001. Sponsored by: AIAA. (Draper Report no. P-3925)

Abstract: This paper presents an overview of the development of inertial components, starting with early rocket guidance using spinning mass components through the development of competent munitions using MEMS sensors. It is a compilation of information on evolving gyroscope and accelerometer use in specific system applications, rather than on the sensor development itself. It shows how the component technology changed over the years in the areas of aircraft navigation, submarine inertial navigation, intercontinental and submarine-launched ballistic missile guidance, space systems, and tactical missiles and munitions. Where possible, the description is chronologically based.

Subjects: INERTIAL COMPONENTS, COMPETENT MUNITIONS ADVANCED TECHNOLOGY DEMONSTRATION (CMATD), MICROELECTROMECHANICAL SYSTEM (MEMS)

Barbour, N.M; Schmidt, G.

Inertial Sensor Technology Trends

IEEE Sensors Journal, Vol. 1, No. 4, December 2001, pp. 332-339. (CSDL-P-3858-REV-A)

Abstract: This paper presents the status of inertial sensor technology in underwater navigation applications, followed by a prediction of where inertial instrument technology is heading and in which applications the future sensor technologies will find a niche. Many kinds of sensors have been developed. The GPS is cheap and ubiquitous, but it is uncertain whether it would be continuously available in military scenarios.

Subjects: INERTIAL SENSORS; GUIDANCE, NAVIGATION, AND CONTROL (GN&C); TECHNOLOGY FORECASTING; TECHNOLOGY DEVELOPMENT; GLOBAL POSITIONING SYSTEM (GPS); INERTIAL NAVIGATION; MOBILE ROBOTS; SENSORS; UNDERWATER VEHICLES; UNDERWATER NAVIGATION; INERTIAL INSTRUMENTS; MILITARY APPLICATIONS

Barbour, N.M.

MEMS for Navigation - a Survey

Institute of Navigation National Technical Meeting. Held in Long Beach, CA, 01/22/2001 to 01/24/2001. Sponsored by: ION. (Draper Report no. P-3871)

Subjects: MICROELECTROMECHANICAL SYSTEM (MEMS), INERTIAL NAVIGATION SYSTEMS (INS), GLOBAL POSITIONING SYSTEM (GPS), OVERVIEW

Barrows, T.M.

Apparent Mass of Parafoils with Spanwise Camber

Aerodynamic Decelerator Systems Technology. 16th. Held in Boston, MA, 05/21/2001 to 05/24/2001, pp. 96-104. Sponsored by: AIAA. (Draper Report no. P-3865)

Abstract: For an arbitrarily shaped body there may be more than one center of apparent mass. The apparent mass of a parafoil shape for motions along various axes is computed using potential flow analysis. From this, the 6 x 6 apparent mass matrix about some reference point is computed. Parametric forms for estimating the terms are given. The existence of multiple mass centers results in off-diagonal terms in this matrix that couple the translational and rotational motions. It is shown how the nondiagonal 6 x 6 apparent inertia matrix about a certain reference point can be used to compute the corresponding apparent mass matrix at any other reference point. Dynamic equations, including nonlinear terms are presented.

Subjects: PARAFOILS, APPARENT MASS, PARAMETRIC ANALYSIS, NONLINEAR EQUATIONS

Barton, G.H.

New Methodologies for Assessing the Robustness of the X-34 Autolanding Trajectories

Guidance and Control Conference. 24th. Held in Breckenridge, CO, 01/31/2001 to 02/04/2001, pp. 193-214. Sponsored by: AAS. (Draper Report no. P-3866)

Abstract: An Autolanding I-load Program (ALIP) has been developed for the rapid design of 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 glide slope, circular flare, exponential flare to shallow glide slope). The motivation for this paper is to develop a rapid methodology to quantify the robustness of the trajectory design for satisfying the landing requirements within vehicle constraints when in the presence of uncertainties in aerodynamics, vehicle, environment, and winds. The approach taken involves using the ALIP-set of nonlinear equations and defining an aeromechanic term for quantifying the energy potential. Examples will be given on quantifying the level of robustness using touchdown footprints, energy disturbance rejection and maximum wind profiles, with and without the benefit of an air data system.

Subjects: X-34, AUTOLANDING I-LOAD PROGRAM (ALIP), TRAJECTORY CONTROL, LANDING

Bedrossian, N.S.; Jang, J.-W.; McManis, J.; Tempelton, J.

eSim: a Software Architecture for Web-Enabled Simulation

Enabling Technology for Simulation Science. 5th. Held in Orlando, FL, 04/17/2001 to 04/20/2001, pp. 145-152. Sponsored by: SPIE. (Draper Report no. P-3902)

Abstract: eSim was developed by Draper-Houston to provide a distributed analysis and simulation capability. It is a concept and architecture for Web-enabled simulation. It utilizes a Client/Server construct to Web-enable any simulation. First-generation eSim is a general-purpose simulation server. With eSim, any simulation can be executed, input parameters entered, and results viewed either in text format, graphically, or via animation from a standard Web browser. Additional software and modifications to existing simulations are not required. eSim(i) provides an interactive capability that allows changing input parameters and viewing corresponding results during the simulation. It also provides the capability to run the simulation in "real-time" mode. Examples are used to illustrate eSim and eSim(i) capabilities.

Subjects: SIMULATION, WORLD WIDE WEB (WWW), EXTERNAL ENVIRONMENT SIMULATOR (ESIM), COMPUTER PROGRAMS (SOFTWARE, COMPUTER SOFTWARE, COMPUTER SYSTEMS PROGRAMS)

Bloom, I.B.K.

Analytical Evidence of PEEK Processing Differences

American Chemical Society (ACS) Northeast Regional Meeting (NERM). Held in Durham, NH, 06/24/2001 to 06/27/2001. Sponsored by: ACS. (Draper Report no. P-3878)

Abstract: Subtle variations in the compression-molded vs. extrusion processing of polyetheretherketone (PEEK) have been linked to defects in precision ball bearing retainers. Freshly extruded PEEK was found to be dimensionally stable after it was cut into precision parts. Problems in the machining process led to a switch to the use of compression-molded rods of the same polymer base stock. Uniformity issues arose with the use of this material. This presentation traces the analytical process and the use of different thermal analysis techniques that identified the root problem. Heat treatments and age-induced crystallization play a role in the identification of which PEEK provides all the desired characteristics.

Subjects: POLYETHERETHERKETONE (PEEK), BALL BEARING RETAINERS, DEBURRING

Boelitz, F.; Gibson, C.

Ascent Load Management Using Wind Look-Ahead Sensors

Guidance and Control Conference. 24th. Held in Breckenridge, CO, 01/31/2001 to 02/04/2001, pp. 69-83. Sponsored by: AAS. (Draper Report no. P-3879)

Abstract: Winds, which vary in magnitude and direction throughout ascent, are an important environmental factor influencing the design and operation of launch vehicles. The combination of wind-induced aerodynamic loads and large propulsive forces requires rocket designers to carefully balance the need for structurally robust vehicles against the need for low weight in order to maximize payload lifting capability and operational efficiency. An on-board or aircraft-based wind look-ahead sensor (most likely Doppler LIDAR) coupled to a new guidance and control system that incorporates this improved wind knowledge in a closed-loop fashion would improve the load management and launch on demand capabilities of current systems. Improved load management would decrease the frequency of launch delays (slips) by expanding the acceptable launch envelope. Reducing expected environmental load dispersions could lead to reducing the weight of those structures primarily influenced by the wind, which in turn would increase the fraction of the payload delivered to orbit. This paper presents both the operational concept and some load management results using a model-based predictive control (MBPC) method. Simulations have shown dramatic reduction in Q-alpha loads and bending moments with the implementation of an MBPC control law using a wind look-ahead sensor.

Subjects: WIND SENSORS, LAUNCH VEHICLES, LIDAR, MODEL-BASED PREDICTIVE CONTROL (MBPC)

Borenstein, J.T.; King, K.R.; Terai, H.; Vacanti, J.P.

Capillary Formation in Microfabricated Polymer Scaffolds

Materials Research Society (MRS) Symposium. Held in Boston, MA, 11/26/2001 to 11/30/2001. Sponsored by: MRS. (Draper Report no. P-3917)

Abstract: One of the primary challenges for engineering thick, complex tissues such as vital organs is the requirement for a vascular supply for nutrient and metabolite transfer. Earlier work has shown that solid freeform fabrication techniques such as three-dimensional printing (3DP) are capable of producing biodegradable scaffolds for the subsequent formation of a wide range of tissues and organs. While this approach shows great promise as a method for constructing complex tissues and organs in vitro, the resolution of the process is currently limited to length scales larger than the narrowest capillaries in the microcirculation. In this work, microfabrication technology is demonstrated as an approach for organizing endothelial cells in vitro at the size scale of the microcirculation. Standard process techniques utilized to build MEMS (Microelectromechanical Systems) devices include photolithography, silicon and glass micromachining, and polymer replica molding. Photolithography is used to print a model network of blood vessels on silicon wafers; the network is designed to replicate the fluid dynamics of the vasculature of a particular tissue or organ. A reverse image of the channel network is formed either by deep reactive ion etching (DRIE) of silicon or through the use of a thick negative-polarity photoresist (SU-8). Polymeric scaffolds are formed by replica molding, using the silicon wafer as a master mold. Microfluidic chambers have been constructed from polydimethylsiloxane (PDMS) and other biocompatible polymers. Initial cell seeding experiments demonstrate that rat lung endothelial cells attach in a single layer to the walls of these structures without occluding them, providing early evidence that MEMS process technology can serve as a method for organizing capillary networks.

Subjects: MICROELECTROMECHANICAL SYSTEM (MEMS), POLYMERS, MICROFABRICATION

Borenstein, J.T.; Terai, H.; King, K.R.; Kaazempur-Mofrad, M.R.; Weinberg, E.J.; Vacanti, J.P.

Microfabrication Technology for Vascularized Tissue Engineering. Abstract Only

BioMEMS and Biomedical Nanotechnology World. 2nd. Held in Columbus, OH, 09/22/2001 to 09/25/2001. (Draper Report no. P-3913A)

Abstract: Loss or failure of a vital organ is one of the most critical problems facing the health care field today. For the first time, the number of individuals in the United States awaiting an organ for transplant has risen above 75,000. In spite of advances in living donor organ transplantation, a severe shortage of donor organs available to these patients remains as the crux of the problem. Mechanical and bioartificial devices represent one avenue to address the organ shortage, while other researchers are working to establish xenografts as a viable alternative. In parallel with these efforts, the field of tissue engineering is undergoing rapid growth, based on early successes in culturing and expanding cells to form replacement tissues such as skin, bone, and cartilage. Tissue engineering, unlike the aforementioned alternatives, represents a complete and permanent solution to the problem of organ loss or failure. This work addresses the application of microfabrication technology toward the engineering of vital organs that require a blood supply. The primary challenge for tissue engineering vital organs is the requirement for a vascular supply for nutrient and metabolite transfer. In one approach, cells are harvested and expanded on a biodegradable polymer scaffold, and factors that promote angiogenesis and blood vessel in-growth are added to form the blood supply for the organ. However, for thick, complex tissues such as the liver, kidney, and heart, the lack of an intrinsic blood supply becomes a major limitation in forming the engineered organ. In this work, a novel approach is described in which the organ's vasculature is engineered in vitro. The core technology for this process is microfabrication, in which a blueprint for the microcirculation is built into the biodegradable scaffold. The process begins with the generation of a fluid dynamic model that replicates the physiology of blood flow in the target organ, and that accounts for nonlinear blood rheology and the effects of hematocrit. This model forms the basis of the lithographic templates used to pattern the blood vessel network in the micromachining process. Master molds are then produced using high-aspect-ratio micromachining methods, typically either silicon etching or thick photoresist processes. Polymer films are cast in the master molds and are integrated to form thick, three-dimensional scaffolds for cell seeding and expansion. Endothelial cells are introduced via dynamic seeding in the microfluidic network, while parenchymal cells are introduced through the interstices of the scaffold matrix. Initial work has focused on the fabrication of scaffolds produced using either nondegradable, biocompatible templates, or biodegradable templates based on polylactic/polyglycolic or other resorbable polymer systems. Microfluidic networks have been designed, built, and tested, and have produced highly uniform flow patterns that mimic large-scale physiologic properties such as total flow rate, as well as small-scale phenomena such as fluid velocity in the capillaries. Early cell seeding results demonstrate successful attachment and proliferation of endothelial cells along the walls of the microfluidic channels as small as 15 microns in diameter. The current focus is to scale up the technology to a full, three-dimensional system with the blood volume and cell density required for a complete organ.

Subjects: TISSUE ENGINEERING, ORGAN TRANSPLANTS, MICROFABRICATION

Brock, L.D.

Role of Open Systems in Implementing Navy HUMS

American Helicopter Society International. 57th. Held in Washington, DC, 05/09/2001 to 05/11/200, pp. 191. Sponsored by: AHS. (Draper Report no. P-3892)

Abstract: The Navy's Integrated Mechanical Diagnostics Health and Usage Monitoring System (IMD-HUMS) is being designed with an open-system architecture. This paper explores the particular type of open system being developed for IMD-HUMS. Open systems can exist at several different levels from the unit level to a functional level. The scope of the systems covered by a particular open-system architecture can also vary over a broad range from a single platform to the whole domain for that class of system. These different types of open systems will have different characteristics and different purposes and advantages. The IMD-HUMS open-system is being designed for a particular purpose at a specific level. The IMD-HUMS open system architecture is being established at the functional level to allow the design of third-party HUMS technology modules for integration into the system. The open system architecture applies to the IMD-HUMS system being developed for the Navy by BFGoodrich Aerospace. The open system is being validated by the integration of five Joint Advanced Health and Usage Monitoring System (JAHUMS) Advanced Concepts Technology Demonstration (ACTD) technology modules for demonstrations of their operational effectiveness.

Subjects: JOINT ADVANCED HEALTH AND USAGE MONITORING SYSTEM (JAHUMS), OPEN SYSTEMS, ADVANCED TECHNOLOGY DEMONSTRATION (ATD)

Chari, R.J.; Geller, D.K.; Norris, H.L.; D'Souza, C.N.; Brand, T.J.

Autonomous Orbital Rendezvous Using Angles-Only Navigation

Astrodynamics Specialist Conference. Held in Quebec City, Canada, 07/30/2001 to 08/02/2001. Sponsored by: AAS/AIAA. (Draper Report no. P-3932)

Abstract: This paper describes techniques for orbital rendezvous and close approach where navigation is accomplished with angles-only measurements. The ability to determine distance along the line-of-sight is enhanced by a combination of techniques. First, the relative trajectory between the chaser and target is designed to create changes in the line-of-sight, enhancing the observability of relative position. Second, the chaser executes maneuvers designed to further enhance the observability of the position component along the line-of-sight. The target vehicle is assumed to be nonmaneuvering and in a near-circular orbit, but the basic techniques should extend to modestly elliptical orbits. The modeled system includes several representative mission scenarios.

Subjects: ORBITAL RENDEZVOUS, ANGLES-ONLY NAVIGATION

Connelly, J.; Kourepenis, A.; Marinis, T.; Hanson, D.

Micromechanical Sensors in Tactical GN&C Applications

Guidance, Navigation, and Control Conference. Held in Montreal, Quebec, Canada, 08/06/2001 to 08/09/2001. Sponsored by: AIAA. (Draper Report no. P-3930)

Abstract: Micromachined silicon inertial sensors offer revolutionary improvements in cost, size, and reliability for guidance, navigation, and control (GN&C). Batch manufacturing techniques produce thousands of virtually identical microelectromechanical system (MEMS) devices, each a few square millimeters in size. Development of inertial MEMS is driven by the high-volume, commercial market that targets modest performance applications at prices below $10 per axis. Draper Laboratory has recently demonstrated higher performance, multi-axis systems using commercial processes for lower-volume tactical applications ranging from guided munitions to microsatellites. More accurate sensors enabled by deep reactive ion etch technology and new digital electronics are rapidly approaching bias stabilities of 1 deg/h and 100 micro-g over -40°C to +85°C. Future architectures under development reflect a radical departure from early demonstration systems. New sensors with complementary input axes have led to multi-axis sensor arrays, and new wafer-scale processes, integrating sensor arrays, and application-specific integrated circuits (ASICs) are creating complete systems on a chip.

Subjects: GUIDANCE, NAVIGATION, AND CONTROL (GN&C); MICROELECTROMECHANICAL SYSTEM (MEMS)

Cunningham, B.; Weinberg, M.; Pepper, J.; Clapp, C.; Bousquet, R.; Hugh, B.; Kant, R.; Daly, C.; Hauser, E.

Design, Fabrication, and Vapor Characterization of a Microfabricated Flexural Plate Resonator Sensor and Application to Integrated Sensor Arrays

Sensors and Actuators B - Chemical, Vol. B73, No. 2, 3/10/01, pp. 112-123. (Draper Report P-3797-FINAL)

Abstract: A chemical vapor detection and biosensor array based on microfabricated silicon resonators coated with thin-film polymer sorption layers is described. The resonators within the array are microelectromechanical (MEM) flexural plate wave (FPW) sensors that have been miniaturized to allow many independently addressable sensors to be integrated within a single silicon chip. The target analyte of an individual sensor within the chip is selected by placing a polymer coating onto the resonating membrane. Detection is performed by monitoring changes in the frequency and damping factor of the resonance as the coating interacts with the environment. This work documents vapor response characterization of an individual sensor element within an array and reports on the operation of an eight-element sensor array. Polymer coatings targeted toward detection of chemical weapon agents have been applied to the sensor and chemical vapor exposure tests using two chemical weapon simulants and four vapor phase interferents have been performed. Data describing temperature dependence, long-term/short-term drift stability, detection limits, detection linearity, and vapor selectivity will be presented. The use of resonant damping information is shown to provide the ability to discriminate between vapor analytes that produce equal resonant frequency shifts.

Subjects: CHEMICAL VAPOR DEPOSITION (CVD), BIOSENSORS, FLEXURAL WAVES, MICROELECTROMECHANICAL SYSTEM (MEMS)

DiMatteo, R.S.; Greiff, P.; Finberg, S.L.; Young-Waithe, K.A.; Choy, H.K.H.; Masaki, M.M.; Fonstad, C.G.

Enhanced Photogeneration of Carriers in a Semiconductor Via Coupling Across a Nonisothermal Nanoscale Vacuum Gap

Applied Physics Letters, Vol. 79, No. 12, 9/17/01, pp. 1894-1896. (Draper Report no. P-3899-FINAL)

Abstract: Enhanced generation of carriers when a thermophotovoltaic cell is placed in submicron proximity to a heated surface is demonstrated using custom-designed InAs photodiodes and special silicon-based heater chips produced using microelectromechanical system techniques. The short-circuit current of the photocells is shown to increase sharply (up to fivefold) when the spacing between the heater and photodiode surfaces is reduced, while at the same time, the heater temperature decreases, consistent with increased radiative transfer between the two surfaces. By varying the spacing sinusoidally (at up to 1 kHz), it is demonstrated that the increase in the short-circuit current occurs in phase with the decrease in separation, thereby ruling out thermal effects. It is argued that the increase in short-circuit current is due to increased evanescent coupling of blackbody radiation from the hot surface to the cold photocell, consistent with recent theoretical predictions. The demonstration of this effect is the initial step in the development of a class of energy conversion devices.

Subjects: THERMOPHOTOVOLTAICS (TPV), CHARGE CARRIERS, PHOTOCELLS, ENERGY CONVERSION, VIAS

Eiceman, G.A.; Tadjikov, B.; Krylov, E.; Nazarov, E.G.; Miller, R.A.; Westbrook, J.; Funk, P.

A Miniature RF-Mobility Analyzer as a Gas Chromatographic Detector: Oxygen-Containing Volatile Organic Compounds, Pheromones, and Other Insect Attractants

Journal of Chromatography A, Vol. 917, No. 1, 5/11/01, pp. 205-217. (Draper Report no. P-3856)

Abstract: A high electric field, radio-frequency ion mobility analyzer (RF-IMS) was used as a small detector in gas chromatographic separations of mixtures of volatile organic compounds, including alcohols, aldehydes, esters, ethers, pheromones, and other chemical attractants for insects. The detector was equipped with a 2 m Ci63Ni ion source and the drift region for ion characterization was 34 mm wide x 20 mm long and 0.6 mm high. The rate of scanning for the compensation voltages was 60 V s-1 and permitted 4 to 6 scans to be obtained across a capillary chromatographic elution profile for each component. The RF-IMS scans were characteristic of a compound and provided a second dimension of chemical identity to chromatographic retention adding specificity in instances of co-elution. Limits of detection were 1.6 to 55 x 10-11 g with an average detection limit for all chemicals of 9.4 x 10-11 g. Response to mass was linear from 2 to 50 x 10-10 g with an average sensitivity of 4 pA ng-1. Separations of pheromones and chemical attractants for insects illustrated the distinct patterns obtained from gas chromatography with RF-IMS scans in real time and suggest an analytical utility of the RF-IMS as a small, advanced detector for on-site gas chromatographs.

Subjects: RADIO FREQUENCIES; ION MOBILITY; GAS CHROMATOGRAPHY; INSECTS

Gupta, N.; Plump, J.

Design of a VTOL Micro Air Vehicle that Incorporates Counter-Rotating, Reversible Thrust Propellers

AUVSI 2001. Held in Baltimore, MD, 07/31/2001 to 08/02/2001. Sponsored by: AUVSI. (Draper Report no. P-3919)

Abstract: The miniaturization of electronic guidance and navigation systems has opened a new frontier in aviation. The opportunity now exists to develop miniature aerial vehicles capable of autonomous flight. Such vehicles could perform reconnaissance missions in environments that are unsafe to humans. Their small size minimizes their chance of being detected in hostile areas and allows them mobility not afforded by typical full-size vehicles and humans. The Charles Stark Draper Laboratory has developed a 12-in VTOL Micro Aerial Vehicle design capable of high-speed forward flight. The innovative design incorporates a pair of counter-rotating, variable pitch propellers enclosed in a protective duct structure. Independent control of propeller pitch provides thrust and yaw control for the vehicle while in a hover mode. Translation control is provided by four independently actuated control surfaces that are placed in the area of high-speed flow aft of the propeller disks. In its forward flight mode, the duct acts as the primary lifting surface and the control surfaces act as movable canard wings. Power is provided by a commercial-off-the-shelf 0.25 in3 displacement 2-stroke glow-fuel engine. A volume of 9 in3 has been reserved in the main fuselage to house the Draper Microelectromechanical integrated navigation package. A payload sensor bay with a volume of 3 in3 has also been incorporated into the design.

Subjects: MICRO AIR VEHICLES (MAV), AUTONOMY, VERTICAL TAKEOFF AIRCRAFT (VTOL AIRCRAFT)

Hamelin, J.L.; Jackson, M.C.; Kirchwey, C.B.; Pileggi, R.A.; Sackett, L.L.

STS-99 Shuttle Radar Topography Mission Stability and Control

Astrodynamics Specialist Conference. Held in Quebec City, Canada, 07/30/2001 to 08/02/2001. Sponsored by: AAS/AIAA. (Draper Report no. P-3929)

Abstract: The Shuttle Radar Topography Mission (SRTM) flew aboard Space Shuttle Endeavor February 2000 and used interferometry to map 80% of the Earth's landmass. SRTM employed a 200-ft deployable mast structure to extend a second antenna away from the main antenna located in the Shuttle payload bay. Mapping requirements demanded precision pointing and orbital trajectories from the Shuttle on-orbit Flight Control System (FCS). Mast structural dynamics interaction with the FCS impacted stability and performance of the autopilot for attitude maneuvers and pointing during mapping operations. A damper system added to ensure that mast tip motion remained within the limits of the outboard antenna tracking system while mapping also helped to mitigate structural dynamic interaction with the FCS autopilot. Late changes made to the payload damper system, which actually failed on-orbit, required a redesign and verification of the FCS autopilot filtering schemes necessary to ensure rotational control stability. In-flight measurements using three sensors were used to validate models and gauge the accuracy and robustness of the premission notch filter design.

Subjects: STS-99, SHUTTLE RADAR TOPOGRAPHY MISSION, FLIGHT CONTROL SYSTEMS (FCS)

Hammett, R.

Design by Extrapolation: An Evaluation of Fault-Tolerant Avionics

Digital Avionics Systems Conference. 20th. Held in Daytona Beach, FL, 10/14/2001 to 10/18/2001, pp. 1C51-1C512. Sponsored by: IEEE. (Draper Report no. P-3889)

Abstract: Over the past 30 years, safety-critical avionics systems such as Fly-By-Wire (FBW) flight controls, full-authority digital engine controls, and other systems have been introduced on many commercial and military airplanes and spacecraft. Early FBW systems, such as on the F-16 and Airbus A320, were considered revolutionary and were introduced with extreme caution. These early systems and their successors all make use of redundant and fault-tolerant avionics to provide the required dependability and safety, but have used significantly different architectures. This paper examines the different levels of criticality and fault tolerance required by different types of avionics systems, establishes architectural categories of fault-tolerant architectures, and identifies the discriminating features of the different approaches. Examples of discriminators include the level of redundancy, methods of engaging backup systems, protection from software errors, and the use of dissimilar hardware and software. The strengths and weaknesses of the different approaches will be identified. The paper concludes with some speculation on trends for future systems based on this evaluation of previous systems.

Subjects: FLY-BY-WIRE CONTROL, AVIONICS, FAULT-TOLERANT SYSTEMS

Hammett, R.C.

Networking Intelligent Components to Create Intelligent Spacecraft

IEEE Aerospace Conference. Held in Big Sky, MT, 03/10/2001 to 03/17/2001. Sponsored by: IEEE. (Draper Report no. P-3850)

Abstract: Spacecraft utilize complex digital electronic controls to perform their missions. Although these systems have benefited from the availability of ever-faster computers and miniaturized electronics, overall control system architectures have changed little, utilizing a shared, centralized computer programmed to service many subsystems. These centralized systems perform well, but are a challenge to design and integrate, requiring complex custom software, custom input/output (I/O) electronics and extensive vehicle wiring. The availability of microprocessors, memories, and serial data terminals small and rugged enough to be embedded directly into subsystem mechanical components has opened the door to revolutionary new distributed architectures. These so-called "smart" or intelligent components can be interconnected into a network to form a distributed architecture. This paper discusses work done to define these distributed architectures and to construct prototype components. Important issues addressed include the physical network required to distribute data and power to components, highly reliable, fault-tolerant operation, the importance of industry standards, and a discussion of packaging and installation considerations.

Subjects: INTELLIGENT CONTROL SYSTEMS, SPACECRAFT, INPUT/OUTPUT MODELS, SCALABLE FAULT-TOLERANT INTELLIGENT NETWORK OF X(TRANS)DUCERS (SFINX)

Hattis, P.; Fill, T.; Rubenstein, D.; Wright, R.; Benney, R.; LeMoine, D.

Status of an On-Board PC-Based Airdrop Planner Demonstration

Aerodynamic Decelerator Systems Technology. 16th. Held in Boston, MA, 05/21/2001 to 05/24/2001, pp. 1-11. Sponsored by: AIAA. (Draper Report no. P-3880)

Abstract: Precision airdrop from high altitude is important for a range of missions while limiting risk to carrier aircraft. Since 1998, the New World Vistas program has sponsored the development of a Draper Laboratory onboard Precision Aerial Delivery Planner and a Planning Systems, Inc. WindPADS wind/density field estimator to address these mission requirements. The resulting system derives an airdrop Computed Aerial Release Point on-board the carrier aircraft while in-flight to the Drop Zone (DZ). This enables adaptation to DZ changes while accurately accounting for current environment data. Reference trajectories for low-glide airdrop systems are also generated en route to the DZ. Two Ethernet-connected laptop personal computers are being used for the Planner, with its embedded airdrop simulation, and for WindPADS. The Planner PC also has access to data from the carrier aircraft 1553 data bus. Interfaces between the PCs and to the carrier aircraft have been tested successfully. Data are being collected by the Army to improve the Planner's parachute model fidelity. The software for both PCs is in the final development and testing phase. A summer 2001 flight demonstration is planned involving airdrops of a ballistic round parachute, a ballistic cross parachute, and a low-glide round parachute.

Subjects: AIRDROP TECHNOLOGY, PRECISION AERIAL DELIVERY PLANNER, COMPUTER SYSTEMS

Hopkins, R.E.

The Pendulous Integrating Gyroscope Accelerometer (PIGA) from the V-2 to Trident D5, the Strategic Instrument of Choice

Guidance, Navigation, and Control Conference. Held in Montreal, Quebec, Canada, 08/06/2001 to 08/09/2001, Paper no. AIAA-2001-4288. Sponsored by: AIAA. (Draper Report no. P-3923)

Abstract: For over 50 years, the inertial guidance industry has developed successive generations of increasingly accurate guidance, navigation, and control (GN&C) systems for intercontinental ballistic missiles (ICBM) and submarine-launched ballistic missiles (SLBM). The comparatively short time of guided flight and high acceleration levels characteristic of the ballistic missile application place a premium on accelerometer performance to achieve desired weapon system accuracy. To date, the accelerometer design of choice for strategic missiles has been the Pendulous Integrating Gyroscopic Accelerometer (PIGA) style instrument, an accelerometer whose origins trace back to the German V-2 rocket, and has been refined through several generations of development to achieve unsurpassed performance. This article will trace the evolution of the PIGA, starting with its initial development for the V-2, through its early adaptation by the U.S. GN&C industry for the pioneering Titan and Polaris ICBM/SLBM systems, to its current state-of-the-art incarnation: the 10-PIGA, which is employed in the Trident II D5 missile. Some of the specialized technologies of PIGA accelerometers, such as gas-bearing wheels, ultrastable ball bearings, precision electromagnetic components, and "designer chemical" flotation fluids will be discussed. Finally, this article will conclude with a brief discussion of new trends in inertial instrument design, and offer some unexpected similarities and contrasts between the new generation of solid-state instruments and the PIGA.

Subjects: PENDULOUS INTEGRATING GYRO ACCELEROMETER (PIGA), INTERCONTINENTAL BALLISTIC MISSILES (ICBM), SUBMARINE-LAUNCHED BALLISTIC MISSILES (SLBM)

Johnson, W.; Phillips, R.

Low-Power Avionics Sensor Suite (LOPASS) NASA New Millennium Program Space Technology 6: Space Avionics

Space. Held in Albuquerque, NM, 08/28/2001 to 08/30/2001. Sponsored by: AIAA. (Draper Report no. P-3926)

Subjects: LOW-POWER ATTITUDE SENSOR SUITE (LOPASS), NEW MILLENNIUM PROGRAM

Johnson, W.M.; Phillips, R.E.

Space Avionics Stellar-Inertial Subsystem

Digital Avionics Systems Conference. 20th. Held in Daytona Beach, FL, 10/14/2001 to 10/18/2001, pp. 8.D.2-1-9. Sponsored by: IEEE. (Draper Report no. P-3893)

Abstract: Draper Laboratory has developed a space avionics system for attitude determination and control of small low-power microsatellites. This work has been funded by the NASA New Millennium Program (NMP). The goal is to determine microsatellite attitude to better than 0.1 deg with a minimum power expenditure. The revolutionary, enabling technologies that make this happen include an Electron-Bombarded Charge-Coupled Device (EBCCD) star camera that can detect dim stars (Magnitude=8) and a Microelectromechanical System (MEMS) 3-axis inertial rate sensor module. These enabling devices have been developed at Draper over the last 10 years and represent relatively mature technology. The performance of the two enabling sensors (EBCCD and MEMS) depends on the early amplification and digital conversion of the optical and inertial signals, respectively, to a digital format. The amplification of the optical signal in the EBCCD star camera removes the effect of the CCD detector noise and the effect of the read-out noise. The digital conversion of the inertial sensor data at the preamplifier stage eliminates the subsequent effect of the noise and drift error terms. The immediate NASA application is microsatellites in Low Earth Orbit (LEO) NASA science missions that often require 20-rpm spinning microsatellites. This paper will describe some of the design features of the Draper Low-Power Avionics Sensor Suite (LoPASS) approach, including the digital processing of the EBCCD and MEMS data. Examples of the LoPASS sensor's digital processing include: use of the UTMC 69R000 microcontroller to implement the digital processing, measuring star centroids on a discrete CCD array with high accuracy, providing digital temperature compensation for the MEMS gyros, application of a simple Kalman filter to optimize the attitude solution, and low-power operation with rad-hard sensors and processor. The result is a space avionics stellar-inertial subsystem that weighs approximately 1 kg and has an average power of approximately 2 W. The optical camera, inertial sensors, and the microcontroller are all rad-hard. The star camera is turned on every 5 min with a 3-s star sighting to update the MEMS gyro drift and achieve the 0.1-deg attitude knowledge requirement.

Subjects: AVIONICS, NEW MILLENNIUM PROGRAM, ATTITUDE DETERMINATION, ATTITUDE CONTROL, MICROSATELLITES

Johnson, W.; Phillips, R.

Stellar/Inertial (EBCCD/MEMS) Attitude Measurement and Control of all Small Satellites

Space. Held in Albuquerque, NM, 08/28/2001 to 08/30/2001. Sponsored by: AIAA. (Draper Report no. P-3896)

Abstract: This paper describes a miniature stellar-inertial subsystem that is being developed for application on small satellites. The goal is to determine the satellite attitude to better than 0.1 deg with a minimum power expenditure. NASA has funded Draper Laboratory to participate in Phase A of the Space Technology-6 (ST-6) portion of the New Millennium Program (NMP). Our task is to demonstrate that the Draper Low-Power Avionics Sensor Suite (LoPASS) concept has been developed and meets the needs described above. The system is being designed to accommodate both NASA science missions that often require 20-rpm spinning microsatellites, as well as inertially stabilized spacecraft. The revolutionary, enabling technologies include an Electron-Bombarded Charge-Coupled Device (EBCCD) star camera that can detect dim stars (Magnitude=8) at high readout rate and a Microelectromechanical System (MEMS) 3-axis inertial rate sensor module. These enabling devices have been developed at Draper over the last 10 years and represent relatively mature technology. The unique aspect of the LoPASS concept is the use of a MEMS gyro with modest performance (deg/h) to achieve very effective performance. This is done with the periodic attitude update from the EBCCD star camera, as well as careful measuring and modeling of the LoPASS system dynamics. By varying the stellar update rate, we can effectively trade star camera power for attitude performance. This paper will describe some of the design features of the Draper LoPASS approach and will discuss the progress that has been made on the current laboratory demonstration. The ongoing LoPASS Pseudo-Star Demonstration will be described, including the novel techniques used to detect the dim stars, locate the 20-rpm spin axis (line of sight (LOS)) in inertial space, and update the MEMS gyro error characteristics. Future plans for space flight test demonstration hardware and the introduction of these systems into operational spacecraft will be discussed.

Subjects: LOW-POWER ATTITUDE SENSOR SUITE (LOPASS), ELECTRON-BOMBARDED CHARGE-COUPLED DEVICE (EBCCD), MICROELECTROMECHANICAL SYSTEM (MEMS)

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

Application Requirements of Artificial Muscles for Swimming Robots

Electroactive Polymer, Actuators, and Devices-Smart Structures and Materials. Held in Newport Beach, CA. 03/05/2001 to 03/08/2001, pp. 364-374. Sponsored by: SPIE. (Draper Report no. P-3882)

Abstract: In the near future, we will find biomimetic undersea robots in the forefront of unmanned underwater applications due to their ability to operate in new, challenging, and highly dynamic environments such as rivers, surf, and turbulent pipe flow. In particular, fish-like vehicles (FLVs) have emerged as a viable technology for highly maneuverable, efficient, and stealthy platforms. Attempts to produce fish-like motion using conventional mechanical means have proved difficult, however, resulting in complex and unreliable machines, especially when compared to the simplicity of a rotating propeller and conventional control surfaces. To take full advantage of fish-like propulsion, a new actuation strategy is needed, to which artificial muscles may be uniquely suited. Some artificial muscles are made of materials with relatively low specific gravity (compared to conventional mechanical systems), and so will be nearly neutrally buoyant in underwater applications. This is critical in FLV actuation, as correct longitudinal mass distribution is required to avoid stability problems. Additionally, some artificial muscle formulations require water, sometimes including an electrolyte, which is easily provided in underwater applications. Finally, for stealthy applications, artificial muscles may provide acoustically quiet actuation due to their suppleness and reduced number of interconnecting mechanical components. In this paper, we suggest artificial muscle-based actuation strategies for FLVs, based on experience with the Vorticity Control Unmanned Undersea Vehicle (VCUUV), an 8-ft long autonomous robotic tuna. Recently developed artificial muscles are surveyed and evaluated as to their suitability for fish-like propulsion. Requirements for force, power, and strain as well as implementation issues are discussed.

Subjects: VORTICITY CONTROL UNMANNED UNDERSEA VEHICLE (VCUUV), FISH-LIKE VEHICLES (FLV), SWIMMING, ROBOTIC TUNA, MUSCLES

King, K.R.; Terai, H.; Wang, C.C.; Vacanti, J.P.; Borenstein, J.T.

Microfluidics for Tissue Engineering Microvasculative: Endothelial Cell Culture

Miniaturized Chemical and Biochemical Analysis Systems. 5th. Held in Monterey, CA, 10/21/2001 to 10/25/2001. Sponsored by: CASSS. (Draper Report no. P-3909)

Abstract: Development of an integrated blood supply is a critical step toward tissue engineering vital organs. We are attempting to engineer microvasculature using microfluidic networks for the guidance of endothelial cell growth. In this work, we have focused on fabrication of the microfluidic scaffold, in vitro seeding, and extended cell culture in the device. Capillary networks were fabricated in biocompatible polydimethylsiloxane (PDMS), sterilized, coated with cell adhesion molecules, and seeded with cells. Cell-containing devices were then connected to a closed-loop bioreactor for long-term culture. We have used the device to demonstrate continuous-flow culture of endothelial cells for up to 4 weeks without occlusion or contamination.

Subjects: TISSUE ENGINEERING, MICROFLUIDICS, MICROVASCULAR SYST