Browse Topic: Attitude control

Items (202)

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 Satellites

TBMG-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 SmallSats

TBMG-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 program

SAE-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 Suspensions

2019-01-045604/02/2019

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 Systems

TBMG-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 Feedback

TBMG-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 CubeSats

TBMG-28561

03/01/2018

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 Software

TBMG-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 Analysis

TBMG-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 Models

2016-32-002711/08/2016

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 Uncertainty

2016-36-037710/25/2016

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 Systems

2016-36-040210/25/2016

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 Mechanism

TBMG-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 Thrusters

TBMG-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 Systems

2015-36-044509/22/2015

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

3D Motor for Multi-Axis Attitude Control on SmallSats

TBMG-22858

09/01/2015

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 System

TBMG-22174

06/01/2015

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 Control

TBMG-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 Damper

2015-26-018101/14/2015

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 Modes

2014-36-036809/30/2014

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 Challenges

2014-01-221409/16/2014

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 Capabilities

TBMG-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 Signature

TBMG-19188

03/01/2014

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.