Browse Topic: Attitude control

Items (256)
Find
Automatic Pilot InstallationsARP419B (Current)04/14/2020
These recommendations cover the mechanical and electrical installation and installation test procedures for automatic pilots of the type normally used in transport type aircraft. The material in this ARP does not supercede any airworthiness requirement in the Civil Air Regulations.
A-4 Aircraft Instruments Committee
Multifunctional Structure Stabilizes and Rotates SatellitesTBMG-3636204/01/2020
Many satellites are in space to take photos. But a vibrating satellite, like a camera in shaky hands, can’t get a sharp image. Pointing it at a precise location to take a photo or perform another task is an important function that requires accuracy. Researchers have developed a way to cancel out the vibrations of a satellite by vibrating the solar panels in the opposite direction — called active noise cancellation.
De-Orbit Device for SmallSatsTBMG-3570212/01/2019
To decrease de-orbit time and allow for higher-altitude orbits of small satellites, researchers at NASA and the University of Florida have developed a retractable drag device capable of modulating drag area while providing 3-axis stabilization. The device increases area without increasing mass, increasing the ability to control rotation and attitude in 12U, 15-kg CubeSats and other small satellites.
Collins Aerospace provides avionics for C-130H modernization programSAE-MA-0000209/03/2019
The Lockheed C-130H Hercules fleet operated by the Air National Guard and U.S. Air Force Reserve is getting new Collins Aerospace Systems avionics that will help extend the life of the legacy aircraft by 20 years.
Kucinski, William
Attitude Control of the Vehicle with Six In-Wheel Drive and Adaptive Hydro Pneumatic Suspensions2019-01-045604/02/2019
The ability of actively adjusting attitude provides a great advantage for those vehicles used in special environments such as off-road environment with extreme terrains and obstacles. It can improve vehicles’ stability and performance. This paper proposes an attitude control system for realizing the active attitude adjustment and vehicle motion control in the same time. The study is based on a vehicle with six wheel independent drive and six independent suspensions (6WIDIS), which is a kind of unmanned vehicle with six in-wheel drives and six independent hydro pneumatic suspensions. With the hydro- pneumatic suspensions, the vehicle’s attitude can be actively adjusted. This paper develops a centralized- distributed control strategy with attitude information obtained by multi-sensor fusion, which can coordinate the complex relationship among the six wheels and suspensions. The attitude control system consists of three parts. The first part is the attitude determination that includes
Li, Boxin, Zheng, Gangtie, Wang, Zhaokui
Ray Optics Simulation of Inertial Navigation SystemsTBMG-3328511/01/2018
Attitude detection is a crucial element in aircraft and spacecraft navigation. The motion of an aircraft consists of a translational component (motion of its center of mass with respect to the Earth) and a rotational component (rotation of the aircraft around its center of mass). Attitude detection is the measurement of the rotational component of the aircraft's motion, and depending on the mission this measurement might need to be extremely accurate. Advances in computer simulation technology have made it easier than ever to set up high-fidelity numerical simulations of inertial navigation and attitude control systems of the type typically found aboard aircraft and spacecraft.
Calculation of Weapon Platform Attitude and Cant Using Available Sensor FeedbackTBMG-2878304/01/2018
When firing artillery, there is typically a maximum angle that the platform cannot exceed relative to the Earth plane. This is due to the large recoil forces involved and the risk of destabilizing the platform the weapon is mounted to. Mobile systems are particularly sensitive to this as the attitude of the platform relative to Earth is constantly changing. A simple solution is to add pitch and roll sensors directly to the platform. However, many mobile systems already have an assortment of sensors that can be used to calculate the platform attitude.
Gimbal for Steering Propelled CubeSatsTBMG-2856103/01/2018
NASA is preparing for the next generation of CubeSats that are propelled and will make directional maneuvers. The new gimbal mount provides a seat for the motor, and controls the position of the thrusters that propel the CubeSat as it moves about and/or changes orbits.
Soil Moisture Active-Passive Project Spacecraft Flight SoftwareTBMG-2816001/01/2018
The Soil Moisture Active-Passive (SMAP) Project Spacecraft Flight Software controls all aspects of command and data handling (CDH) in the SMAP spacecraft. Required capabilities include uplink and command, telemetry and downlink, vehicle attitude control, science instrument control, onboard science data storage and downlink, spacecraft deployments, and spacecraft fault detection and response.
Wallops Arc-Second Pointer (WASP)TBMG-2802412/01/2017
The Wallops Arc Second Pointer (WASP) is a balloon-borne attitude control system capable of pointing a telescope or instrument with accuracy and stability down to the arc second, or 1/3600 of a degree of angular measurement. When a high-powered telescope is integrated with WASP, it provides a highly precise platform for conducting astronomical research. To date, the WASP system has been tested aboard five helium-filled scientific balloons at altitudes between 100,000 – 125,000 feet with flight durations up to 15 hours. During these pathfinder missions, the WASP controlled instrument structures with masses between 1,000 – 2,000 lbs.
Interface Between STAR-CCM+ and 42 for Enhanced Fuel Slosh AnalysisTBMG-2614801/01/2017
Fuel slosh is excited during spacecraft maneuvers. The forces and torques exerted on the spacecraft by the slosh must be controlled by the attitude control system to maintain correct pointing and spacecraft orbit. In some rare cases, the attitude control system may excite the slosh and cause a loss of control of the spacecraft, or the expected spacecraft motion from a certain control command will be different enough from the control command to adversely affect the mission. By linking the computational fluid dynamics (CFD) and the flight simulation software, the fuel slosh can be modeled at high fidelity by the CFD software, while receiving and passing information to and from the flight simulation software, thus increasing the fidelity of both models. In the past, fuel slosh has either been modeled with an equivalent mechanical model, such as a pendulum, or with a standalone CFD simulation.
Analysis of Low-Cost MEMS Accelerometer and Gyroscope Characteristics for Stochastic Sensor Simulation within Motorcycle Models2016-32-002711/08/2016
Vehicle dynamics control (VDC) for motorcycles had a fast growth during the last 10 years. The available technologies comprise curve-safe ABS and traction control (TC) systems, anti-wheelie control, right up to comprehensive motorcycle stability systems including even more control functions. VDC systems rely on real-time information about the current motorcycle dynamic state. Thus motorcycles are equipped with additional sensor units, namely MEMS inertial measurement devices, capable of gathering accelerations and angular rates. The application of model-based estimation theory enables the determination of the necessary information about the in-plane and out-of-plane motion, e.g. the motorcycle lean angle. Since VDC systems include safety critical control functions, the validation within simulations including sensor characteristics is mandatory. The MEMS accelerometer and gyroscope features include low-cost and small footprint, however there are considerable stochastic sensor errors to
Winkler, Alexander, Grabmair, Gernot
H Infinity Attitude Controller Design for a Rigid-Flexible Satellite Considering the Parametric Uncertainty2016-36-037710/25/2016
In designing of the Attitude Control System (ACS) is important take into account the influence of the structure’s flexibility, since they can interact with the satellite rigid motion, mainly, during translational and/or rotational maneuver, damaging the ACS pointing accuracy. In the linearization and reduction of the rigid-flexible satellite mathematic model, usually one loses some important information associated with the satellite true dynamical behavior. One way to recovery this information is include to the ACS design parametric and not parametric uncertainties of the system. The H infinity control method is able to take into account the parametric uncertainty in the control law design, so the controller becomes more robust. This paper presents the design of a robust controller using the H infinity control technique to control the attitude of a rigid-flexible satellite. The satellite model is represented by a flexible beam connected to a central rigid hub considering a set of
Souza, Alain Giacobini, Souza, Luiz Carlos Gadelha
A First Strategy for Smoothing Transients in Switching Controls of Aerospace and Automotive Systems2016-36-040210/25/2016
Switching controls are those that can switch between control or plant modes to perform their functions. They have the advantage of being simpler to design than an equivalent control system with a single mode. However, the transients between those modes can introduce steps or overshootings in the state variables, and this can degrade the performance or even damage the control or the plant. So, the smoothing of such transients is vital for their reliability and mantainability. This is can be of extreme importance in the aerospace and automotive fields, plenty of switchings between manual and autopilot modes via relays, or among gears via clutches, for example. In this work, we present a first strategy for smoothing transients in switching controls of aerospace and automotive systems. To do that, we review the literature, present and adopt a criterion to determine the coefficients of a control system which should optimize the trajectory of the control signal during the switching between
Amaral, Jairo Cavalcanti, de Oliveira e Souza, Marcelo Lopes
Deployable Perimeter Truss with Blade Reel Deployment MechanismTBMG-2409803/01/2016
Solar sail technology depends heavily on the total surface area of the sail. In other words, minimizing mass and volume of its support structure is the main objective, particularly when it comes to launch configuration, i.e. mass, volume constraints, etc. There is a need to develop a low-cost concept of a deployable support structure that can stow in the EELV Secondary Payload Adapter (ESPA) volume, and carries as much sail material as possible. This structure must then be able to deploy the sail material out, and provide the surface area needed.
Six-Degree-of-Freedom Control With Only Eight ThrustersTBMG-2346212/01/2015
Typical spacecraft thruster configurations are often unable to provide full six-degree-of-freedom control and may have unwanted interaction between their attitude control and trajectory control functions, have undesirably high instantaneous electrical power demands, and use more thrusters than desirable. These last two potential problems gain increased significance if a spacecraft is required to have especially small size and mass, and have very low cost.
Integral of Modulus of Error Control for Smoothing Signals when Switching Modes of Aerospace and Automotive Systems2015-36-044509/22/2015
Control systems that can switch between control or plant modes have the advantage of being simpler to design than an equivalent system with a single mode. However, the transition between these modes can introduce steps or overshootings in the state variables, and this can degrade the performance or even damage the system. This is can be of extreme importance in fields such as aerospace and automobilistic, as the switching between manual and autopilot modes or the switching of gears In this work, we will use integral criteria in original ways, to determine a coefficient on the system which should optimize the trajectory of the control signal, during the switching between two modes. Effectively, each transition will be done by a subsystem specific for it, according to the selected criterion. The simulations will be made in MATRIXx, MatLab or both, using models chosen from aerospace or automobilistic fields.
Amaral, Jairo Cavalcanti, de Oliveira e Souza, Marcelo Lopes
Testing Touch Screens in Realistic Aeronautic Turbulent Conditions (Light to Severe)2015-01-253209/15/2015
As touch screens are everywhere in the consumer market Thales has launched in depth evaluations on their introduction in the cockpit. One of the challenges is to verify its compatibility with in flight use under turbulence conditions, including light, moderate and severe. In flight accelerometer collections were performed to provide us with a baseline for choosing between possible simulation solutions. Thales recognized early on the need for such a tool as it would enable us to define recommendations for our HMI designs. The objectives were first to validate specific complex touch/gestures using all the potential of touch interactions for novel cockpit Human Machine Interfaces and second to look into the various physical anchoring solutions capable of facilitating touch screens interactions in aeronautical turbulent environments. Given the 6 axis accelerometer profiles that were collected, only an hexapod structure was capable of reproducing those profiles with acceptable validity
Hourlier, Sylvain, Guérard, Sandra, BAROU, Jean Luc, Servantie, Xavier
3D Motor for Multi-Axis Attitude Control on SmallSatsTBMG-2285809/01/2015
Preliminary data was recently provided for a reaction sphere prototype on NASA’s zero-gravity parabolic flight vehicle. Gyroscope telemetry indicates that reaction spheres were successfully commanded at 10- to 20-ms pulses during a handful of parabolas in each flight. This is the first publicly disclosed validation of a freely rotating reaction sphere in a standalone compact package. At dimensions of
Precision Miniature Attitude Determination and Control SystemTBMG-2217406/01/2015
The MAI-400SS Space Sextant is a turnkey Attitude Determination And Control System (ADACS) for CubeSats and nanosatellites. It is an enhanced version of the MAI-400, which is a precision CubeSat ADACS incorporating three reaction wheels, three electromagnets, and an ADACS computer in a ½-U module. This Space Sextant version incorporates two star trackers to improve overall pointing knowledge to 0.02° or better. The star trackers feature “Lost In Space” attitude determination requiring no a priori information.
Pyramid Micro-Electrofluidic-Spray Propulsion Thruster with Integrated Attitude and Thrust Vector ControlTBMG-2177504/01/2015
A micro-electrofluidic-spray propulsion (MEP) system was built on a micro scale, in which arrays of hundreds of nano-thrusters are etched on silicon wafers like ICs, only a centimeter on a side. Many dozens of these thruster chips can be arrayed to form a macro-thruster of finite and significant thrust. Approximately 300 centimeter-square, 100-micro-Newton micro-thrusters are arrayed in a square pyramidal structure. The pyramid is of shallow obliquity, with no more than 20° offset from the spacecraft face. This small angular offset is sufficient to provide thrust vector control (TVC) for the thruster.
Attitude Control Using Stability Augmentation System for a Military Vehicle Using Active Damper2015-26-018101/14/2015
This study is made on a simplified pitch model of an armored fighting vehicle. Jerks and angular acceleration inside the vehicle compartment Affects accurate firing attack and reduced fatigue to the occupants in Vehicle. The Stability Augmentation Technique can enhance the stability and ride comfort of the vehicle platform from road and firing disturbance. The force requirement for stabilizing the platform is calculated from the displacement of vehicle body in terms of pitch angle and Heave displacement with respect to the equilibrium position, the equivalent force at suspension mounting points required to stabilize the platform is calculated using a force transformation technique. The required force is given by an active Damper for stabilization, within the limit of damper capacity. From simulation conducted and comparison with passive suspension it is perceived that the Stability of vehicle platform is increased together with a reduced VDV (Vibration Dose Value) and rms acceleration
Trikande, Mukund, Muralidharan, Sujithkumar, Jagirdar, Vinit
A Method with Intergral Criteria to Determine Optimal Transitions between Control Modes2014-36-036809/30/2014
Control systems that can switch between control modes have the advantage of being simpler to design than an equivalent system with a single mode. However, the transition between control modes can introduce steps or overshootings in the state variables, and this can degrade the performance or even damage the system. In this work, we will use integral criteria in an original way, to determine a coefficient on the system which should optimize the trajectory of the control signal, during the switching between two modes. Effectively, each transition will be done by a subsystem specific for it, according to the selected criterion. The simulations will be made in MATRIXx, using as models the system of control of attitude of the Multimission Platform, and a system which keeps the synchrony between two induction motors.
Amaral, Jairo Cavalcanti, de Oliveira e Souza, Marcelo Lopes
Systems Engineering - Directions and Challenges2014-01-221409/16/2014
This article attempts to provide a big picture of systems engineering in both philosophy and engineering perspectives, discusses current status and issues, trends of systems engineering development, future directions and challenges, followed by certain examples.
Lu, Manxue
Quick Thrust Profile Design Analysis for Verifying Spacecraft Operational CapabilitiesTBMG-1958905/01/2014
A paper describes a process for imposing safety constraints on a spacecraft trajectory design. The conventional process has the ACS (Attitude Control System) team define geometric constraints, then the NAV (Navigation) team produces a compliant thrust direction profile for the spacecraft to execute. With time-varying thrust profiles, merely specifying geometric constraints is not sufficient. Because low thrust implies low agility under thrust vector control (TVC), even slowly developing spacecraft dynamics can be significant and geometric constraints can have dynamic implications. The thrust profile design process was modified to incorporate a new tool, known as qSTAT, which analyzes candidate thrust profiles for compliance with geometric and dynamic constraints by simulating an appropriately reduced set of spacecraft dynamics. qSTAT gives the navigation team a simplified attitude control simulation tool that can quickly be used to analyze multiple candidate thrust profile designs. The
Spacecraft Line-of- Sight Stabilization Using LWIR Earth SignatureTBMG-1918803/01/2014
Until the time of this reporting, when a space vehicle required a reference signal for inertial pointing, the choices were a signal beacon from an Earth location, the Earth radiance in the visible spectrum, or a star tracker. However, limitations can arise from using these techniques. For example, the signal beacon suffers from limited signal power (either in RF or optical) and will constrain the application to limited ranges, errors due to stray-light and centroiding limit the accuracy of a star tracker, and the spatial/temporal variability of the Earth’s albedo and its illumination by the Sun introduces limitations when used in the visible or near infrared light.
Chuck Taylor, Principal Investigator, NASA Langley Research Center, Hampton, VATBMG-1712008/01/2013
Chuck Taylor: Solar Electric Propulsion is a form of spacecraft propulsion used in space. It relies on the acceleration of ions using electricity generated by solar arrays instead of the chemical energy stored in the propellant itself. It is attractive because by using the Sun’s energy in the process we can bring considerably less propellant mass into orbit; this reduces our launch mass and cost. An SEP system is usually considered to consist of the large arrays that generate electric power, the power processing units or PPUs that convert this power, and the thruster which uses the electric power to ionize the inert propellant and accelerate it out of the spacecraft to generate thrust.
CRUQS: A Miniature Fine Sun Sensor for NanosatellitesTBMG-1697508/01/2013
A new miniature fine Sun sensor has been developed that uses a quadrant photodiode and housing to determine the Sun vector. Its size, mass, and power make it especially suited to small satellite applications, especially nanosatellites. Its accuracy is on the order of one arcminute, and it will enable new science in the area of nanosatellites.
Estimating the Backup Reaction Wheel Orientation Using Reaction Wheel Spin Rates Flight Telemetry from a SpacecraftTBMG-1685807/01/2013
A report describes a model that estimates the orientation of the backup reaction wheel using the reaction wheel spin rates telemetry from a spacecraft. Attitude control via the reaction wheel assembly (RWA) onboard a spacecraft uses three reaction wheels (one wheel per axis) and a backup to accommodate any wheel degradation throughout the course of the mission. The spacecraft dynamics prediction depends upon the correct knowledge of the reaction wheel orientations. Thus, it is vital to determine the actual orientation of the reaction wheels such that the correct spacecraft dynamics can be predicted.
Space Operations Learning Center (SOLC) iPhone/iPad ApplicationTBMG-1660706/01/2013
This iPhone application, Space Junk Sammy, is intended to be an educational application designed for Apple iPhones and iPads. This new concept educates kids in an innovative way about how orbital debris affects space missions.
Cloud Absorption Radiometer Autonomous Navigation System — CANSTBMG-1658106/01/2013
CAR (cloud absorption radiometer) acquires spatial reference data from host aircraft navigation systems. This poses various problems during CAR data reduction, including navigation data format, accuracy of position data, accuracy of airframe inertial data, and navigation data rate. Incorporating its own navigation system, which included GPS (Global Positioning System), roll axis inertia and rates, and three-axis acceleration, CANS expedites data reduction and increases the accuracy of the CAR end data product.
Advanced Materials and Fabrication Techniques for the Orion Attitude Control MotorTBMG-1633005/01/2013
Rhenium, with its high melting temperature, excellent elevated temperature properties, and lack of a ductile-to-brittle transition temperature (DBTT), is ideally suited for the hot gas components of the ACM (Attitude Control Motor), and other hightemperature applications. However, the high cost of rhenium makes fabricating these components using conventional fabrication techniques prohibitive. Therefore, near-net-shape forming techniques were investigated for producing cost-effective rhenium and rhenium alloy components for the ACM and other propulsion applications.
Bob Reisse, ALHAT Project Manager, Langley Research Center, Hampton, VA.TBMG-1601303/01/2013
Bob Reisse coordinates the design and testing of ALHAT (Autonomous Landing Hazard Avoidance Technology) sensors. In December, ALHAT instruments were melded to HUEY helicopters, which used sensors and an integrated computer system to provide guidance and assist pilots. The technology will also enable landing near specific resources and locations across the solar system, including the moon, Mars, and other asteroids.
Electromagnetic Compatibility (EMC) System Design ChecklistAIR1221 (Current)02/24/2013
This checklist is to be used by project personnel to assure that factors required for adequate system electromagnetic compatibility are considered and incorporated into a program. It provides a ready reference of EMC management and documentation requirements for a particular program from preproposal thru acquisition. When considered with individual equipments comprising the system and the electromagnetic operational environment in which the system will operate, the checklist will aid in the preparation of an EMC analysis. The analysis will facilitate the development of system-dependent EMC criteria and detailed system, subsystem, and equipment design requirements ensuring electromagnetic compatibility.
AE-4 Electromagnetic Compatibility (EMC) Committee
Estimating Torque Imparted on Spacecraft Using TelemetryTBMG-1549001/01/2013
There have been a number of missions with spacecraft flying by planetary moons with atmospheres; there will be future missions with similar flybys. When a spacecraft such as Cassini flies by a moon with an atmosphere, the spacecraft will experience an atmospheric torque. This torque could be used to determine the density of the atmosphere. This is because the relation between the atmospheric torque vector and the atmosphere density could be established analytically using the mass properties of the spacecraft, known drag coefficient of objects in free-molecular flow, and the spacecraft velocity relative to the moon. The density estimated in this way could be used to check results measured by science instruments. Since the proposed methodology could estimate disturbance torque as small as 0.02 N-m, it could also be used to estimate disturbance torque imparted on the spacecraft during high-altitude flybys.
Who's Who at NASA: Jack Vieira, Range Project ManagerTBMG-1377106/01/2012
In March of 2012, NASA successfully launched five rockets from its Wallops Flight Facility in Virginia. The launch was part of NASA's Anomalous Transport Rocket Experiment, or ATREX, which will help scientists better understand the jet stream. Jack Vieira, range project manager for the ATREX mission, helped to launch five suborbital rockets more than 60 miles above Earth.
Spacecraft Attitude Tracking and Maneuver Using Combined Magnetic ActuatorsTBMG-1265901/01/2012
A paper describes attitude-control algorithms using the combination of magnetic actuators with reaction wheel assemblies (RWAs) or other types of actuators such as thrusters. The combination of magnetic actuators with one or two RWAs aligned with different body axis expands the two-dimensional control torque to three-dimensional. The algorithms can guarantee the spacecraft attitude and rates to track the commanded attitude precisely.
Passive Attitude Control for Discoid Aerial Vehicles2011-01-278710/18/2011
This paper presents and investigates different passive methods for reducing the notorious instability of discoid aerial vehicles. Presented methods are completely passive and involve elementary causes such as aerodynamic forces and gravitational effects. Four different system attitude control methods are presenting for different shapes and constructive solutions…
Dumas, Antonio, Trancossi, Michele
Miniature, Variable-Speed Control Moment GyroscopeTBMG-1071808/01/2011
The Miniature Variable-Speed Control Moment Gyroscope (MVS-CMG) was designed for small satellites (mass from less than 1 kg up to 500 kg). Currently available CMGs are too large and heavy, and available miniature CMGs do not provide sufficient control authority for use on practical satellites. This primarily results from the need to greatly increase the speed of rotation of the flywheel in order to reduce the flywheel size and mass. This goal was achieved by making use of a proprietary, space-qualified, high-speed (100,000 rpm) motor technology to spin the flywheel at a speed ten times faster than other known miniature CMGs under development.
Monitoring Spacecraft Telemetry Via Optical or RF LinkTBMG-1076508/01/2011
A patent disclosure document discusses a photonic method for connecting a spacecraft with a launch vehicle upper-stage telemetry system as a means for monitoring a spacecraft’s health and status during and right after separation and deployment. This method also provides an efficient opto-coupled capability for prelaunch built-in-test (BIT) on the ground to enable more efficient and timely integration, preflight checkout, and a means to obviate any local EMI (electromagnetic interference) during integration and test. Additional utility can be envisioned for BIT on other platforms, such as the International Space Station (ISS).
Planning the FUSE Mission Using the SOVA AlgorithmTBMG-1076408/01/2011
Three documents discuss the Sustainable Objective Valuation and Attainability (SOVA) algorithm and software as used to plan tasks (principally, scientific observations and associated maneuvers) for the Far Ultraviolet Spectroscopic Explorer (FUSE) satellite. SOVA is a means of managing risk in a complex system, based on a concept of computing the expected return value of a candidate ordered set of tasks as a product of pre-assigned task values and assessments of attainability made against qualitatively defined strategic objectives.
Six Degrees-of-Freedom Ascent Control for Small-Body Touch and GoTBMG-990305/01/2011
A document discusses a method of controlling touch and go (TAG) of a spacecraft to correct attitude, while ensuring a safe ascent. TAG is a concept whereby a spacecraft is in contact with the surface of a small body, such as a comet or asteroid, for a few seconds or less before ascending to a safe location away from the small body.
Observation Scheduling SystemTBMG-942703/01/2011
Software has been designed to schedule remote sensing with the Earth Observing One spacecraft. The software attempts to satisfy as many observation requests as possible considering each against spacecraft operation constraints such as data volume, thermal, pointing maneuvers, and others. More complex constraints such as temperature are approximated to enable efficient reasoning while keeping the spacecraft within safe limits. Other constraints are checked using an external software library. For example, an attitude control library is used to determine the feasibility of maneuvering between pairs of observations. This innovation can deal with a wide range of spacecraft constraints and solve large scale scheduling problems like hundreds of observations and thousands of combinations of observation sequences.
Study on a Fault-Tolerant System Applied to an Aerospace Control System2010-36-033010/06/2010
On several engineering applications high Reliability is one of the most wanted features. The aspects of Reliability play a key role in design projects of aircraft, spacecraft, automotive, medical, bank systems, and so, avoiding loss of life, property, or costly recalls. The highly reliable systems are designed to work continuously, even upon external threats and internal Failures. Very convenient is the fact that the term 'Failure' may have its meaning tailored to the context of interesting, as its general definition refers to it as "any deviation from the specified behavior of a system". The above-mentioned 'deviation' may refer to: performance degradation, operational misbehavior, deviation of environmental qualification levels, Safety hazards, etc. Nevertheless, Reliability is not the only requirement for a modern system. Other features as Availability, Integrity, Security and Safety are always part of the same technical specification, in a same level of importance. This paper
Neto, Humberto Manelli, de Oliveira e Souza, Marcelo Lopes
Determining Atmospheric-Density Profile of TitanTBMG-850309/01/2010
A method was developed for measuring the atmospheric density of Titan, the largest moon of Saturn, to create an accurate density profile as a function of altitude. This will allow mission planners to select safe flyby altitudes, and for navigation engineers to accurately predict the delta-v associated with those flybys.
ISS Solar Array ManagementTBMG-794505/01/2010
The International Space Station (ISS) Solar Array Management (SAM) software toolset provides the capabilities necessary to operate a spacecraft with complex solar array constraints. It monitors spacecraft telemetry and provides interpretations of solar array constraint data in an intuitive manner. The toolset provides extensive situational awareness to ensure mission success by analyzing power generation needs, array motion constraints, and structural loading situations.
Ultra-Large Solar SailTBMG-577810/01/2009
UltraSail is a next- generation ultra-large (km2 class) sail system. Analysis of the launch, deployment, stabilization, and control of these sails shows that high-payload-mass fractions for interplanetary and deep-space missions are possible. UltraSail combines propulsion and control systems developed for formation- flying microsatellites with a solar sail architecture to achieve controllable sail areas approaching 1 km2. Electrically conductive CP-1 polyimide film results in sail subsystem area densities as low as 5 g/m2. UltraSail produces thrust levels many times those of ion thrusters used for comparable deepspace missions.
A5ES-ATV: Aerothermodynamical Study of the Deorbitation of the Ariane 5 Upper Composite2009-01-245307/12/2009
This paper is devoted to the methodology and techniques used by ASTRIUM-ST to analyze the aerothermodynamics of the A5 upper composite reentry. Direct Simulation Monte Carlo methods were applied to compute the composite's surrounding flows and thermal fluxes at walls for its different possible attitudes during deorbitation and along its various scenarios' flight paths. The results are then used as inputs for the determination of the composite's thermal behavior and especially of its main wall structures and equipments as well as propellant and helium tanks with the prediction of their rupture and the ejection velocity of their respective fragments.
Jarry, Amauric, Fraioli, Dominique
On-Orbit Performance of the Moon Mineralogy Mapper Instrument2009-01-239007/12/2009
Launched on India's Chandrayaan-1 spacecraft on October 22, 2008, JPL's Moon Mineralogy Mapper (M3) instrument has successfully completed over six months of operation in space. M3 is one in a suite of eleven instruments, six of which are foreign payloads, flying onboard the Indian spacecraft. Chandrayaan-1, managed by the Indian Space Research Organization (ISRO) in Bangalore, is India's first deep space mission. Chandrayaan-1 was launched on the upgraded version of India's Polar Satellite Launch Vehicle (PSLV-XL) from the Satish Dhawan Space Centre, SHAR, Sriharikota, India. The primary science objective of the M3 instrument is the characterization and mapping of the lunar surface composition in the context of its geologic evolution. Its primary exploration goal is to assess and map the Moon mineral resources at high spatial resolution to support future targeted missions. M3 is a cryogenic state of the art “push-broom” near infrared imaging spectrometer with high signal to noise ratio
Rodriguez, Jose I., Tseng, Howard, Varanasi, Padma, Zhang, Burt
Electronic Stability Applications in Commercial Vehicles2008-01-261510/07/2008
Stability control is becoming a standard feature on nearly all cars and trucks manufactured worldwide. This is driving major developments in both inertial sensors and kinematic controls. Inertial sensors include accelerometers and gyroscopes (gyros) which vary in size, cost, and performance. These sensors are compared and matched to various emerging needs for stability control in off-road machines. Kinematic controls are demonstrating that real-time sensing and signal processing can offer better performance and lower cost than typical mechanical solutions for stability. Examples of how these sensors and controls can monitor and achieve electronic stability are illustrated for large and small machines. Finally, guidelines are provided for addressing inertial effects such as gravity for several different comfort and safety applications. It is this challenge that leads to an electronic stability solution that is custom to each machine platform.
Livdahl, Rich, Tevs, Nikolai, Tolstedt, Jonathan
Items per page:
1 – 50 of 256