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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1980

STS-1 operational flight profile. Volume 5: Descent cycle 3. Appendix D: GRTLS six degree of freedom Monte Carlo dispersion analysis

The results of a six degree of freedom (6-DOF) nonlinear Monte Carlo dispersion analysis for the latest glide return to landing site (GRTLS) abort trajectory for the Space Transportation System 1 Flight are presented. For this GRTLS, the number two main engine fails at 262.5 seconds ground elapsed time. Fifty randomly selected simulations, initialized at external tank separation, are analyzed. The initial covariance matrix is a 20 x 20 matrix and includes navigation errors and dispersions in position and velocity, time, accelerometer bias, and inertial platform misalinements. In all 50 samples, speedbrake, rudder, elevon, and body flap hinge moments are acceptable. Transitions to autoland begin before 9,000 feet and there are no tailscrapes. Navigation derived dynamic pressure accuracies exceed the flight control system constraints above Mach 2.5. Three out of 50 landings exceeded tire specification limit speed of 222 knots. Pilot manual landings are expected to reduce landing speed by landing farther downrange.

Montez, M. N.↗
NASA NTRS1980

Control system analysis and synthesis for a six degree-of-freedom universal Force-Reflecting Hand Controller

A six degree-of-freedom joystick with feedback motors, called the Force-Reflecting Hand Controller (FRHC) is used as control input for the human operator in a teleoperator system. The geometric and dynamic properties of the FRHC are entirely different from those of the manipulator being controlled. The paper discusses the analysis and synthesis of the control loop between the FRHC and the robot arm and examines the necessary position and force transformations. The controller is implemented through a dedicated minicomputer.

Handlykken, M.↗
NASA NTRS1987

Multiple degree of freedom optical pattern recognition

Three general optical approaches to multiple degree of freedom object pattern recognition (where no stable object rest position exists) are advanced. These techniques include: feature extraction, correlation, and artificial intelligence. The details of the various processors are advanced together with initial results.

Casasent, D.↗
NASA NTRS1990

Six Degree of Freedom System

This animated clip shows operations of the Six Degree of Freedom (DOF) computer during a simulated mission. The clip is intercut with live video of a shuttle crew 'docking' with Space Station Freedom.

Source record↗
NASA NTRSDate not supplied

Toward Fully 3D-Printed Two Degree of Freedom Acoustic Liners

An acoustic liner optimization tool is developed for designing two degree of freedom (2DOF) liners with high absorption over a wide range of frequencies and sound pressure levels (SPLs). Two additively manufactured 2DOF liners (one constant and one variable chamber depth) are designed and printed with an embedded perforate layer as the septum. A normal incidence impedance tube study is performed to directly compare impedance and absorption spectra to a more traditionally manufactured 2DOF liner with embedded mesh caps in phenolic honeycomb. Comparisons of test data to predictions are shown as well as SPL sensitivities for each acoustic liner. Broadband absorption is achieved with the 3D printed 2DOF liner containing constant chamber depths, although due to current limitations in printed embedded perforate hole size, not as broad as the traditional mesh cap liner. However, results also show that the 3D printed variable chamber depth sample is more comparable to the mesh cap liner absorption, demonstrating the viability of printed embedded perforates in novel concepts.

acoustic liner 2DOF two degree of freedom 3D print↗
NASA NTRS2005

A Generic Inner-Loop Control Law Structure for Six-Degree-of-Freedom Conceptual Aircraft Design

A generic control system framework for both real-time and batch six-degree-of-freedom simulations is presented. This framework uses a simplified dynamic inversion technique to allow for stabilization and control of any type of aircraft at the pilot interface level. The simulation, designed primarily for the real-time simulation environment, also can be run in a batch mode through a simple guidance interface. Direct vehicle-state acceleration feedback is required with the simplified dynamic inversion technique. The estimation of surface effectiveness within real-time simulation timing constraints also is required. The generic framework provides easily modifiable control variables, allowing flexibility in the variables that the pilot commands. A direct control allocation scheme is used to command aircraft effectors. Primary uses for this system include conceptual and preliminary design of aircraft, when vehicle models are rapidly changing and knowledge of vehicle six-degree-of-freedom performance is required. A simulated airbreathing hypersonic vehicle and simulated high-performance fighter aircraft are used to demonstrate the flexibility and utility of the control system.

Cox, Timothy H.↗
NASA NTRS2005

A Generic Guidance and Control Structure for Six-Degree-of-Freedom Conceptual Aircraft Design

A control system framework is presented for both real-time and batch six-degree-of-freedom simulation. This framework allows stabilization and control with multiple command options, from body rate control to waypoint guidance. Also, pilot commands can be used to operate the simulation in a pilot-in-the-loop environment. This control system framework is created by using direct vehicle state feedback with nonlinear dynamic inversion. A direct control allocation scheme is used to command aircraft effectors. Online B-matrix estimation is used in the control allocation algorithm for maximum algorithm flexibility. Primary uses for this framework include conceptual design and early preliminary design of aircraft, where vehicle models change rapidly and a knowledge of vehicle six-degree-of-freedom performance is required. A simulated airbreathing hypersonic vehicle and a simulated high performance fighter are controlled to demonstrate the flexibility and utility of the control system.

Cotting, M. Christopher↗
NASA NTRS2005

A Generic Guidance and Control Structure for Six-Degree-of-Freedom Conceptual Aircraft Design

A control system framework is presented for both real-time and batch six-degree-of-freedom simulation. This framework allows stabilization and control with multiple command options, from body rate control to waypoint guidance. Also, pilot commands can be used to operate the simulation in a pilot-in-the-loop environment. This control system framework is created by using direct vehicle state feedback with nonlinear dynamic inversion. A direct control allocation scheme is used to command aircraft effectors. Online B-matrix estimation is used in the control allocation algorithm for maximum algorithm flexibility. Primary uses for this framework include conceptual design and early preliminary design of aircraft, where vehicle models change rapidly and a knowledge of vehicle six-degree-of-freedom performance is required. A simulated airbreathing hypersonic vehicle and a simulated high performance fighter are controlled to demonstrate the flexibility and utility of the control system.

Cotting, M. Christopher↗
DOE OSTI2020

Probing the Partonic Degrees of Freedom in High-Multiplicity p–Pb collisions at √ s NN = 5.02 TeV

We investigate the role of partonic degrees of freedom in high-multiplicity p–Pb collisions at √ s NN = 5.02 TeV carried out at the Large Hadron Collider (LHC) by studying the production and collective flow of identified hadrons at intermediate p T via the coalescence of soft partons from the viscous hydrodynamics (VISH 2 + 1) and hard partons from the energy loss model, linear Boltzmann transport (LBT). We find that combining these intermediate p T hadrons with the low p T hadrons from the hydrodynamically expanding fluid and high p T hadrons from the fragmentation of quenched jets, the resulting hydro-dynamics-coalescence-fragmentation model provides a nice description of measured p T spectra and differential elliptic flow v 2 (p T ) of pions, kaons, and protons over the p T range from 0 to 6 GeV. We further demonstrate the necessity of including the quark coalescence contribution to reproduce the experimentally observed approximate number of constituent quark scaling of hadron v 2 at intermediate p T . Furthermore, our results thus indicate the importance of partonic degrees of freedom and also hint at the possible formation of quark-gluon plasma in high-multiplicity p–Pb collisions at the LHC.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
NASA NTRS1993

Multiple degree of freedom force-state component identification

Force-state mapping is extended to allow the quasistatic characterization of realistic multiple degree of freedom systems whose constitutive relations are nonlinear, dissipative, coupled and depend on memory of past states. A general constitutive force-state model is formulated, which includes dynamic hysteresis phenomena typical of that found in deployable structures. A two step parameter identification approach is developed, which employs a linear extended Kalman filter and a nonlinear least squares fit. A six degree of freedom force-state testing device was constructed, and used to obtain data on one bay of a simple truss and on one bay of the MODE deployable truss.

Masters, Brett P.↗
NASA NTRS1989

Optimized resolved rate control of seven-degree-of-freedom Laboratory Telerobotic Manipulator (LTM) with application to three-dimensional graphics simulation

The Laboratory Telerobotic Manipulator (LTM) is a seven-degree-of-freedom robot arm. Two of the arms were delivered to Langley Research Center for ground-based research to assess the use of redundant degree-of-freedom robot arms in space operations. Resolved-rate control equations for the LTM are derived. The equations are based on a scheme developed at the Oak Ridge National Laboratory for computing optimized joint angle rates in real time. The optimized joint angle rates actually represent a trade-off, as the hand moves, between small rates (least-squares solution) and those rates which work toward satisfying a specified performance criterion of joint angles. In singularities where the optimization scheme cannot be applied, alternate control equations are devised. The equations developed were evaluated using a real-time computer simulation to control a 3-D graphics model of the LTM.

Barker, L. Keith↗
NASA NTRS1992

A six-degree-of-freedom guidance and control analysis of Mars aerocapture

A six-degree-of-freedom (6DOF) simulation is developed to investigate the control and guidance issues of a Mars aerobraking vehicle. The guidance algorithm used is a predictor-corrector guidance formulation designed to control the exit orbital apoapsis and wedge angle using bank-angle modulation. Major features of this predictor-corrector guidance algorithm include: (1) integration of the 3DOF equations of motion within an inner-loop simulation; (2) load-relief logic; (3) finite roll rates; and (4) an aerodynamic feedback multiplier. The algorithm is capable of successfully guiding the vehicle through combinations of atmospheric density dispersions, aerodynamic mispredictions, and off-nominal atmospheric interface conditions. This study demonstrated that the addition of vehicle dynamics to the Mars aerobraking simulation does not significantly impact mission feasibility. That is, a robust control system design coupled with an adaptive guidance algorithm can assure mission success in the presence of numerous off-nominal conditions.

Powell, Richard W.↗
NASA NTRS2004

A practical six-degree of freedom solar sail dynamics model for optimizing solar sail trajectories with torque constraints

Controlled flight of a solar sail-propelled spacecraft ('sailcraft') is a six-degree-of-freedom dynamics problem. Current state-of-the-art tools that simulate and optimize the trajectories flown by sailcraft do not treat the full kinetic (i.e. force and torque-constrained) motion, instead treating a discrete history of commanded sail attitudes, and either neglecting the sail attitude motion over an integration timestep, or treating the attitude evolution kinematically with a spline or similar treatment. The present paper discusses an aspect of developing a next generation sailcraf trajectory designing optimization tool JPL, for NASA's Solar Sail Spaceflight Simulation Software (SS). The aspect discussed in an experimental approach to modeling full six-degree-of-freedom kinetic motion of a solar sail in a trajectory propagator. Early results from implementing this approach in a new trajectory propagation tool are given.

six-degree-of-freedom↗
DOE OSTI2021

Linear delta systems with additional degrees of freedom and related methods

A linear delta system includes a frame, rails secured to the frame, linear actuators, each linear actuator coupled to a respective rail and configured to translate along a longitudinal length of the respective rail, pairs of parallel rods each operably coupled to a respective linear actuator, a platform coupled to the pairs of parallel rods, structure configured to movable couple an object to the platform; and at least one degree of freedom imparting assembly including a profiled rod extending in a direction parallel to the rails and a drive unit configured to rotate the profiled rod, wherein the at least one degree of freedom imparting assembly is configured to impart a degree of freedom to the object.

Crawford, Anthony L.↗
NASA NTRS1987

The design of a nine-string six-degree-of-freedom force-feedback joystick for telemanipulation

An overview is given of the design and controlling equations for a 6-degree-of-freedom force-feedback joystick for telemanipulation. The joystick has a parallel mechanical structure which allows all of its actuators to be fixed to a non-moving base. The low-inertia design is expected to provide an accurate force-feedback signal to the joystick operator without the need for closed-loop momentum compensation. The analysis describes the joystick's inputs and outputs in generalized Cartesian space, so the joystick can potentially be used as an interface for any 6-degree-of-freedom device.

Agronin, M. L.↗