Overview of the PredGuid Skip Entry Guidance Algorithm

Space Station Zero Propellant Maneuver Flight Results Compared to Eigenaxis

Zero-Propellant Maneuver Concept and Flight Results

Micro RF Tags for Medical Imaging

Enhancement of In Vitro Capillary Tube Formation with Synthetic Nanotopography

Micromachined Surface Stress Sensor with Electronic Readout

Linear Covariance Analysis Techniques Applied to Orion Cislunar Operations

Autonomous Landing and Hazard Avoidance Technology

Target Geolocation from a Small Unmanned Aircraft System

Biodegradable and Biocompatible Gecko-Inspired Tissue Adhesive

Performance Evaluation of Stem Cell Multiresolution Texture Analysis

Vacuum-Sealed MEMS Package with an Optical Window

Performance of an Automated Feature Tracking Lunar Navigation System

Unmanned System Risk Management

Self-Contained Method for Safe and Precise Lunar Landing

Barton, G.H.; Hattis, P.D.; Neave, M.D.; Putnam, Z.R.

Overview of the PredGuid Skip Entry Guidance Algorithm

Aerospace Control and Guidance Systems Committee Meeting, Salt Lake City, UT, 3/5/2008-3/7/2008. Sponsored by: SAE (Draper Report no. P-4656)

Subjects: ENTRY GUIDANCE, ALGORITHMS, CREW EXPLORATION VEHICLES (CEV), CREW MODULE (CM)1

Bedrossian, N.S.; Bhatt, S.A.

Space Station Zero Propellant Maneuver Flight Results Compared to Eigenaxis

Space Flight Mechanics, Galveston, TX, 1/27/2008-1/31/2008. Sponsored by: AAS and AIAA (Draper Report no. P-4631)

Abstract: The first-ever Zero Propellant Maneuver (ZPM) rotated the International Space Station (ISS) 90 deg without using propellant on November 5, 2006. On March 3, 2007, another ZPM reoriented the ISS 180 deg, also without any propellant use. This paper describes the ZPM concept and presents the flight results for these two particular ZPMs in comparison to the corresponding eigenaxis trajectories. The reason a ZPM trajectory can avoid momentum saturation while the eigenaxis cannot is presented. The ZPMs are preplanned trajectories used to command the Control Moment Gyro (CMG) attitude hold controller to perform the maneuver between specified initial and final states while maintaining the CMGs within their operational limits. Each trajectory is obtained by computationally solving an optimal attitude control problem with pseudospectral methods. The ZPM thus provides the capability to control the rotational state of a spacecraft (e.g., large-angle maneuvers, rate damping, momentum dumping, etc.) without the need to use thrusters.

Subjects: ZERO PROPELLANT MANEUVER (ZPM), INTERNATIONAL SPACE STATION (ISS), TRAJECTORIES

Bedrossian, N.S.; Bhatt, S.A.; Lammers, M.L.; Nguyen, L.; Zhang, Y.

Zero-Propellant Maneuver Concept and Flight Results

Air Force Test & Evaluation (T&E) Days, Los Angeles, CA, 2/5/2008-2/7/2008. Sponsored by: AIAA (Draper Report no. P-4633)

Abstract: This paper presents the Zero Propellant Maneuver (ZPM) rotational control concept and its demonstrations in flight. On November 5, 2006, a ZPM was used to reorient the International Space Station (ISS) 90 deg without using any propellant. In addition, a ZPM was used to perform a 180-deg ISS rotation on March 3, 2007. The ZPMs are preplanned trajectories used to command the Control Moment Gyro (CMG) attitude hold controller to perform the maneuver between specified initial and final states while maintaining the CMGs within their operational limits. Each trajectory was obtained from a computational solution to an optimal attitude control problem. The ZPM thus provides the capability to perform large-angle attitude maneuvers, rate damping, momentum desaturation, etc., without the need to use thrusters. This approach is applicable to any spacecraft controlled by momentum storage devices.

Subjects: ZERO PROPELLANT MANEUVER (ZPM), MANEUVERS, TRAJECTORIES, INTERNATIONAL SPACE STATION (ISS)

Bernstein, J.J.; Bancu, M.G.; Ciocan, R.; Lenkinski, R.E.; Marquis, R.P.; Ivanishev, A.; Frangioni, J.V.

Micro RF Tags for Medical Imaging

Solid-State Sensor, Actuator, and Microsystems Workshop, Hilton Head Island, SC, 6/1/2008-6/5/2008. Sponsored by: Transducers Research Foundation (TRF) (Draper Report no. P-4658)

Abstract: This paper presents Micro Resonant Devices (MRDs), which are visible in magnetic resonance imaging (MRI) scans. These LC resonators are fabricated using electroplated spiral inductors combined with thin-film Ta₂O₅ capacitors, formed by a novel oxy-nitride plasma oxidation process. Arrays of resonators were fabricated with diameters of 0.3, 0.5, and 1 mm. To compensate for process variations, resonators were fabricated with parametrically varying capacitor areas. In this study, we characterize the first such devices for their detectability as a function of size in salt-containing aqueous media and in vivo using a clinical MRI scanner and a scanning ultrahigh-frequency (UHF) microscope.

Subjects: MICRODEVICES, IMAGING, MAGNETIC RESONANCE IMAGING (MRI)

Bettinger, C.J.; Zhang, Z.; Langer, R.; Gerecht, S.; Borenstein, J.T.

Enhancement of In Vitro Capillary Tube Formation with Synthetic Nanotopography

Technical Proceedings of the Nanotechnology Science and Technology Institute (NSTI), Boston, MA, 6/1/2008-6/5/2008. Sponsored by: NSTI (Draper Report no. P-4663A)

Abstract: Tissue engineering scaffolds often aim to control cell behavior using a variety of signaling modalities, including chemistry, mechanical properties, and local microenvironmental factors such as oxygen concentration. However, few efforts have explored the use of nanotopography as a means to regulate cell function. Controlling the morphology and function of cells using substrate nanotopography is a phenomenon that can be utilized in a variety of fields, including tissue engineering and regenerative medicine. In this work, we explored the possibility of using nanofabricated surfaces to control the function of endothelial cells to ultimately enhance in vitro vasculargenesis. We chose to culture endothelial progenitor cells (EPCs) on poly(dimethylsiloxane) substrates with ridge-groove geometries of approximately 600 nm in width. EPCs cultured on nanotopographic were found to exhibit enhanced morphological alignment and elongation, reduced proliferation, and enhanced migration. Protein-level expression of endothelial cell markers was not significantly affected by topography, as determined by fluorescent microscopy. However, an in vitro capillary tube formation assay induced the formation of larger, more organized vascular structures in EPCs cultured on nanotopographic versus flat substrates. These results suggest substrate nanotopography could function as a tool for controlling EPC function and achieving enhanced vasculargenesis. Furthermore, these nanotopographic substrates could serve as a template for engineering more complex vascularized tissues and organs.

Subjects: TISSUE ENGINEERING, NANOTOPOGRAPHY, CELLS, MANIPULATING

Carlen, E.T.; Weinberg, M.S.; Dubé, C.E.; Zapata, A.M.; Borenstein, J.T.

Micromachined Surface Stress Sensor with Electronic Readout

Review of Scientific Instruments, Vol. 79, 015106, 1/2008 (Draper Report no. P-4569)

Abstract: A micromachined surface stress sensor has been fabricated and integrated off chip with a low-noise, differential capacitance, electronic readout circuit. The differential capacitance signal is modulated with a high-frequency carrier signal, and the output signal is synchronously demodulated and filtered, resulting in a DC output voltage proportional to the change in differential surface stress. The differential surface stress change of the Au(lll) coated silicon sensors due to chemisorbed alkanethiols is Δσ_s≈-0.42±0.0028 Nm^-1 for 1-dodecanethiol (DT) and Δσ_s≈-0.14±0.0028 Nm^-1 for 1-butanethiol (BT). The estimated measurement resolution (1-Hz bandwidth) is ≈0.12 mNm^-1 (DT: 0.2 pg mm^-2 and BT: 0.8 pg mm^-2) and as high as  ≈3.82 µNm^-1 (DT: 8 fg mm^-2 and BT: 24 fg mm^-2) with system optimization.

Subjects: MICROELECTROMECHANICAL SYSTEMS (MEMS), SURFACE STRESS SENSORS, CAPACITANCE

D'Souza, C.N.; Clark, F.D.

Linear Covariance Analysis Techniques Applied to Orion Cislunar Operations

Space Flight Mechanics Conference, Galveston, TX, 1/27/2008-1/31/2008. Sponsored by: AAS and AIAA (Draper Report no. R-3018)

Abstract: Linear covariance techniques are applied to the cislunar phase of the Orion mission. Both the guidance and navigation systems are analyzed, particularly as they relate to 3-sigma navigation performance and trajectory dispersion. In addition the deltaV statistics will be presented. This paper documents the preliminary integrated analyses performed to provide the expected onboard dispersion and navigation errors.

Subjects: LINEAR COVARIANCE ANALYSIS,CREW EXPLORATION VEHICLES (CEV),CISLUNAR SPACE

Epp, C.D.; Robertson, E.; Brady, T.M.

Autonomous Landing and Hazard Avoidance Technology

Aerospace Conference, Big Sky, MT, 3/1/2008-3/8/2008. Sponsored by: IEEE (Draper Report no. P-4657)

Abstract: The ALHAT Project is funded by NASA to develop an integrated AGN&C (Autonomous Guidance, Navigation and Control) hardware and software system capable of detecting and avoiding surface hazards and guiding humans and cargo safely, precisely, and repeatedly to designated lunar landing sites. There are important interdependencies driving the design of a lunar landing system, including such things as lander hazard robustness, landing site conditions (terrain and natural lighting), trajectories, sensors, crew involvement, and others. The ALHAT system must be capable of operating in a wide range of lunar environments and supporting global lunar access for both crewed and robotic missions. This paper discusses the major factors driving the design of a lunar landing system as well as the current state of the technology development. The supporting analysis and testing results will be presented that show the system interdependencies and their relative importance, as well as the trades needed to optimize the landing system. The emphasis is on the final phase of the landing where Hazard Detection and Avoidance (HDA) and Hazard-Relative Navigation (HRN) are the primary considerations in achieving a safe landing. The current sensor options being considered and the status of the development of those sensors are discussed.

Subjects: AUTONOMOUS GUIDANCE, NAVIGATION, AND CONTROL (AGN&c), AUTONOMOUS HAZARD DETECTION AND AVOIDANCE, LUNAR LANDING

Hattis, P.D.; Moran, B.A.

Enabling Robust and Reliable Spacecraft Function

31st Guidance and Control Conference, Breckenridge, CO, 2/1/2008-2/6/2008. Sponsored by: AAS (Draper Report no. P-4622) 

Abstract: Contemporary spacecraft must realize high levels of reliability while demonstrating robustness to the space environment. This must be done while accommodating tight constraints on component weight, power, and volume as well as meeting mission-specific performance requirements. This paper addresses and compares some of the applicable Guidance, Navigation and Control (GN&C) design trades and solution options for earth orbital spacecraft, vehicles traveling beyond earth orbit, and vehicles transiting an atmosphere during entry from space. Some GN&C-specific component selection considerations associated with spacecraft operating in Earth orbit, cis-lunar flight, lunar orbit, earth entry, and Mars entry are reviewed with account for applicable reliability requirements, performance objectives, and vehicle design constraints.

Subjects: GUIDANCE NAVIGATION AND CONTROL (GN&C), SPACECRAFT REENTRY, SPACECRAFT

Madison, R.W.; DeBitetto, P.A.; Olean, A.R.; Peebles, M.

Target Geolocation from a Small Unmanned Aircraft System

Aerospace Conference, Big Sky, MT, 3/1/2008-3/8/2008. Sponsored by: IEEE (Draper Report no. P-4602)

Abstract: Draper Laboratory and AeroVironment, Inc. of Monrovia, CA, are implementing a system to demonstrate target geolocation from a Raven-B Unmanned Aircraft System (UAS) as part of the U.S. Army Natick Soldier Research, Development & Engineering Center's Small UAS (SUAS) Advanced Concept Technology Demonstration (ACTD). The system is based on feature tracking, line-of-sight calculation, and Kalman filtering from Draper's autonomous vision-aided navigation code base. The system reads imagery and telemetry transmitted by the UAS and includes a user interface for specifying targets. Tests on a snapshot of ongoing work indicate horizontal targeting accuracy of approximately 10 m, compared with 20-60 m for the current Raven-B targeting software operating on the same flight video/telemetry streams. This accuracy likely will be improved through further mitigation of identified error sources. This paper presents our targeting architecture, the results of tests on simulator and flight data, an analysis of remaining error, and suggestions for reducing that error.

Subjects: TARGET GEOLOCATION, UNMANNED AERIAL SYSTEMS (UAS)

Mahdavi, A.; Ferreira, L.S.; Sundback, C.A.; Nichol, J.W.; Chan, E.; Carter, D.J.; Bettinger, C.J.; Patanavanich, S.; Chignozha, L.; Joseph, E.B.; Galakatos, A.; Pryor, H.; Pomerantseva, I.; Masiakos, P.T.; Faquin, W.C.; Zumbuehl, A.; Hong, S.; Borenstein, J.T.; Vacanti, J.P.; Langer, R.; Karp, J.M.

Biodegradable and Biocompatible Gecko-Inspired Tissue Adhesive

Proceedings of the National Academy of Sciences of the USA, Vol. 105, No. 7, 2/19/2008, pp. 2307-2312 (Draper Report no. P-4626)

Abstract: There is a significant medical need for tough biodegradable polymer adhesives that can adapt to or recover from various mechanical deformations while remaining strongly attached to the underlying tissue. We approached this objective by utilizing a novel polymer poly(glycercol sebacic acid acrylate) (PGSA) and modifying the surface to mimic the nanotopography of gecko feet, which allows attachment to vertical surfaces. Translation of existing gecko-inspired adhesives for medical applications is complex as multiple parameters must be optimized, including biocompatibility, biodegradation, strong adhesive tissue bonding, and compliance and conformational matches to tissue surfaces. Ideally these adhesives would also have the ability to deliver drugs or growth factors to promote healing. As a first demonstration, we have created a gecko-inspired tissue adhesive from a biocompatible and biodegradable elastomer combined with a thin tissue reactive, biocompatible surface coating. Tissue adhesion was optimized by varying dimensions of the nanoscale pillars, including the ratio of tip diameter to pitch and the ratio of tip diameter to base diameter. Coating these nanomolded pillars of biodegradable elastomers with a thin layer of oxidized dextran significantly increased the interfacial adhesion strength on porcine intestine tissue in vitro and in the rat abdominal subfascial in vivo environment. This gecko-inspired medical adhesive has potential applications for sealing wounds and for replacement or augmentation of sutures or staples.

Subjects: POLYMERS,TISSUES, ADHESIVES

Mangoubi, R.S.; Desai, M.N.; Sammak, P.J.

Performance Evaluation of Stem Cell Multiresolution Texture Analysis

5th International Symposium on Biomedical Imaging: From Nano to Macro, Paris, France, 5/14/2008-5/17/2008. Sponsored by: IEEE (Draper Report no. P-4617)

Abstract: We apply texture image analysis methods to the problem of automated classification of stem cell nuclei. Using known probability models for the coefficients of texture multiresolution decompositions, we derive likelihood ratio test statistics. We also derive the probability density functions of these non-Gaussian statistics and use them to evaluate the performance of the classification test. Results indicate that the likelihood ratio test can successfully distinguish with probability 0.95 between nuclei that are pluripotent and those with varying degrees of differentiation. The test also recognizes when two nuclei whose level of differentiation is similar by assigning them to the same class, even if prior information says the contrary. Finally, the test statistics and their density functions are applicable to a general texture classification problem.

Subjects: STEM CELLS, TEXTURE CLASSIFICATION

Marinis, T.F.; Soucy, J.W.; Lawrence, J.G.; Marinis, R.T.; Pryputniewicz, R.J.

Vacuum-Sealed MEMS Package with an Optical Window

58th Electronics Components & Technology Conference, Lake Buena Vista, FL, 5/27/2008-5/30/2008. Sponsored by: IEEE (Draper Report no. P-4659)

Abstract: A vacuum-sealed package with an optical window is a useful diagnostic tool for Microelectromechanical Systems (MEMS) devices, as well as a critical component of optical devices, such as imaging bolometers, scanning mirrors, and variable wavelength filters. In either of these applications, the package must meet a number of stringent requirements. It cannot contaminate devices by either outgassing or shedding particulates. The window must be optically flat to allow devices to be observed or measured with interferometric tools when the package is used as a diagnostic tool. When it serves as an integral part of an optical MEMS device, the window must also have the requisite transmissibility over the device's operating wavelength range. The vacuum level in many applications can also be quite challenging to achieve. Typically, pressures less than a few millitorr are necessary to prevent gas damping from limiting attainable Q values. Packages utilized for diagnostic purposes are often subjected to harsh environmental testing to evaluate how MEMS devices respond to mechanical shock, vibration, or thermal shock. Consequently, package robustness, particularly the glass-to-package seal integrity, is an important design element. We have successfully used a sputtered composite structure of gold over platinum over titanium to fabricate a seal ring on the window. The window is attached to a leadless ceramic chip carrier package by soldering with a 50 microns thick eutectic gold-tin preform. The sealing process is to load package assemblies, preforms and windows into a high-vacuum system, degas them, raise the temperature of all components to 325C, bring them into contact, and cool. We have used finite-element analysis (FEM) to optimize the seal geometry as a function of coefficient of thermal expansion (CTE) mismatch, solder material, and window material to meet environmental requirements and optical flatness specifications. We have validated these FEM calculations by subjecting sealed packages to mechanical shock and helium leak testing. The optical flatness of windows was evaluated by direct optical interferometry measurements and high-resolution measurements on sealed MEMS devices. The gas permeability of sealed packages was evaluated by measuring the Q of resonant devices over a period of several months. This fundamental understanding of window design, validated by experimental testing, extends our MEMS packaging capability to support the needs of both diagnostic investigations and optical device packaging.

Subjects: MICROELECTROMECHANICAL SYSTEMS (MEMS), OPTICAL DEVICES

Osenar, M.J.; Clark, F.D.; D'Souza, C.N.

Performance of an Automated Feature Tracking Lunar Navigation System

Space Flight Mechanics Conference, Galveston, TX, 1/27/2008-1/31/2008. Sponsored by: AAS and AIAA (Draper Report no. R-3019)

Abstract: The performance of this automated lunar landmark system has been investigated using linear covariance techniques. Lunar surface feature tracking will be shown to be an effective method for lunar navigation using a digital camera. The camera has been shown to improve performance primarily by decreasing downrange position error in subsequent sightings of a particular feature. Error analysis has shown that the limited knowledge of lunar gravity is the biggest hindrance to navigation performance. With a large feature set and a wide camera field of view, active feature tracking is expected to achieve a 3-sigma RSS position error of under 500 m, and 3-sigma RSS velocity error under 3 m/s in low lunar orbit.

Subjects: LUNAR NAVIGATION, LINEAR COVARIANCE ANALYSIS, LUNAR SURFACE

Page, L.A.; Nervegna, M.F.; DiBiaso, D.M.

Unmanned System Risk Management

International Conference on Robotics and Automation, Pasadena, CA, 5/19/2008-5/23/2008. Sponsored by: IEEE (Draper Report no. P-4592)

Abstract: This paper describes Unmanned System Risk Management, a methodology for managing the risks involved in unmanned vehicle missions. The methodology includes a human/machine collaborative process for risk management that is embedded into a system's broader process for initiating a mission. The methodology also includes an architecture that structures how risk-related information flows throughout the distributed system and how risk information is collected from and presented to the user. It also includes the development and integration of algorithms dedicated to managing specific categories of risk. Each risk category is supported by specific risk analysis and/or mitigation algorithms. The architecture is extendable so that developers can incorporate additional, risk-category-specific algorithms over time without needless complexity. The methodology has been implemented in the Risk-aware Mixed-initiative Dynamic Replanning (RMDR) system, which allows an operator to manage a heterogeneous team of unmanned underwater and air vehicles. RMDR includes autonomy functionality onboard the vehicles as well as on a host platform with an operator in the loop. RMDR currently includes algorithms to analyze and/or mitigate the risks of being detected, of colliding with other vehicles, of running out of energy, and of image collection failure due to environmental conditions. Risk mitigation algorithms are incorporated into both team-level and vehicle-level plan generation.

Subjects: UNMANNED SYSTEMS,RISK MANAGEMENT, RISK-AWARE MIXED-INITIATIVE DYNAMIC REPLANNING PROGRAM (RMDR)

Paschall II, S.C.; Sostaric, R.; Cohanim, B.E.; Brady, T.M.

Self-Contained Method for Safe and Precise Lunar Landing

Aerospace Conference, Big Sky, MT, 3/1/2008-3/8/2008. Sponsored by: IEEE (Draper Report number P-4598)

Abstract: The return of humans to the Moon will require increased capability beyond that of the previous Apollo missions. Longer stay times and a greater flexibility with regard to landing locations are among the many improvements planned. A descent and landing system that can land the vehicle more accurately than Apollo with a greater ability to detect and avoid hazards is essential to the development of a Lunar Outpost and also for increasing the number of potentially reachable Lunar Sortie locations. This descent and landing system should allow landings in more challenging terrain and provide more flexibility with regard to mission timing and lighting considerations, while maintaining safety as the top priority. The lunar landing system under development by the ALHAT (Autonomous precision Landing and Hazard Avoidance Technology) project is addressing this by providing terrain-relative navigation measurements to enhance global-scale precision, an onboard hazard-detection system to select safe landing locations, and an Autonomous Guidance, Navigation, and Control (GN&C) capability to process these measurements and safely direct the vehicle to this landing location. This ALHAT landing system will enable safe and precise lunar landings without requiring lunar infrastructure in the form of navigation aids or a priori identified hazard-free landing locations. The safe landing capability provided by ALHAT uses onboard active sensing to detect hazards that are large enough to be a danger to the vehicle, but too small to be detected from orbit, given current orbital terrain resolution limits. Algorithms to interpret raw active sensor terrain data and generate hazard maps, as well as to identify safe sites and recalculate new trajectories to those sites are included as part of the ALHAT system. These improvements to descent and landing will help contribute to repeated safe and precise landings on the Moon.

Subjects: LUNAR LANDING, AUTONOMOUS PRECISION LANDING AND HAZARD DETECTION AND AVOIDANCE TECHNOLOGY (ALHAT), MOON MISSIONS, GUIDANCE NAVIGATION AND CONTROL (GN&C)