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NASA NTRS2006

Time Triggered Protocol (TTP) for Integrated Modular Avionics

Traditional avionics computing systems are federated, with each system provided on a number of dedicated hardware units. Federated applications are physically separated from one another and analysis of the systems is undertaken individually. Integrated Modular Avionics (IMA) takes these federated functions and integrates them on a common computing platform in a tightly deterministic distributed real-time network of computing modules in which the different applications can run. IMA supports different levels of criticality in the same computing resource and provides a platform for implementation of fault tolerance through hardware and application redundancy. Modular implementation has distinct benefits in design, testing and system maintainability. This paper covers the requirements for fault tolerant bus systems used to provide reliable communication between IMA computing modules. An overview of the Time Triggered Protocol (TTP) specification and implementation as a reliable solution for IMA systems is presented. Application examples in aircraft avionics and a development system for future space application are covered. The commercially available TTP controller can be also be implemented in an FPGA and the results from implementation studies are covered. Finally future direction for the application of TTP and related development activities are presented.

Motzet, Guenter↗

NASA NTRS2018

ATD-2 TTP Traffic Management Messages

This document is the fifth of five documents that describe the TFDM Terminal Publication (TTP) implementation within ATD-2 including data message formats and data schemas.

ATD-2↗

NASA NTRS2018

ATD-2 TTP Flight Delay Messages

This document is the third of five documents that describe the TFDM Terminal Publication (TTP) implementation within ATD-2 including data message formats and data schemas.

message format specification↗

NASA NTRS2018

ATD-2 TTP Airport Information Messages

This document is the first of five documents that describe the TFDM Terminal Publication (TTP) implementation within ATD-2 including data message formats and data schemas.

message format specification↗

NASA NTRS2018

ATD-2 TTP Flight Data Messages

This document is the second of five documents that describe the TFDM Terminal Publication (TTP) implementation within ATD-2 including data message formats and data schemas.

message format specification↗

NASA NTRS2018

ATD-2 TTP Operational Metrics Messages

No abstract available

message format specification↗

NASA NTRS2006

Time Triggered Protocol (TTP) for Integration Modular Avionics (IMA)

This viewgraph presentation is a review of the Time Triggered Protocol, designed to work with NASA's Integrated Safety-Critical Advanced Avionics Communication and Control (ISAACC) system. ISAACC is the product of the Propulsion High-Impact Avionics Technologies (PHIAT) project at NASA Marshall Space Flight Center (MSFC) during FY03 to the end of FY05. The goal is an avionics architecture suitable for control and monitoring of safety critical systems of manned spacecraft. It must be scalable to allow its use in robotic vehicles or launch pad and propulsion test stand monitoring and control systems. The developed IMA should have: a common power supply and rugged chassis for a set of modules, many upgradeable software functions on one module (i.e. processing unit Reduced weight, straightforward update and system integration. It is also important that it have Partitioning and a Memory Management Unit (MMU)

Gwaltney, David A.↗

NASA NTRS2019

Airspace Technology Demonstration 2 (ATD-2): TFDM Terminal Publication Service (TTP)

No abstract available

Gorman, Shawn M.↗

NASA NTRS2019

ATD-2 TFDM Terminal Publication Service (TTP)

Learn the many benefits of the newest SWIM feed from the surface system. This will discuss current options to onboard with this feed, allow participants to ask questions and provide some examples of how the data can be used. Service Includes Flight Data Individual flight updates containing flight identifiers, targeted times, actual times, runway, parking gate, spot, departure fix (predicted, assigned, actual as appropriate), flight states, and more. Airport Information Airport configurations, airport and runway rates, ramp closures, runway closures, taxiway closures. Traffic Management Restrictions Call for Release programs departure MIT/MINIT restrictions, departure stop/ground stop programs. Along with list of impacted flights for each. Flight Delay Airport and runway delay by arrival, departure, and total. Operational Metrics Metrics on airport throughput and individual flight metrics. Surface Metering Program SMP start / end times, metering constraint type / details, updates to existing programs, TMAT compliance window, departure queue length, and more.

Gorman, Shawn M.↗

NASA NTRS1995

Time-to-Passage Judgments in Nonconstant Optical Flow Fields

The time until an approaching object will pass an observer (time to passage, or TTP) is optically specified by a global flow field even in the absence of local expansion or size cues. Kaiser and Mowafy have demonstrated that observers are in fact sensitive to this global flow information. The present studies investigate two factors that are usually ignored in work related to TTP: (1) non-constant motion functions and (2) concomitant eye rotation. Non-constant velocities violate an assumption of some TTP derivations, and eye rotations may complicate heading extraction. Such factors have practical significance, for example, in the case of a pilot accelerating an aircraft or executing a roll. In our studies, a flow field of constant-sized stars was presented monocularly on a large screen. TIP judgments had to be made on the basis of one target star. The flow field varied in its acceleration pattern and its roll component. Observers did not appear to utilize acceleration information. In particular, TTP with decelerating motion were consistently underestimated. TTP judgments were fairly robust with respect to roll, even when roll axis and track vector were decoupled. However, substantial decoupling between heading and track vector led to a decrement in performance, in both the presence and the absence of roll.

Kaiser, Mary K.↗

NASA NTRS1999

Time Temperature-Precipitation Behavior in An Al-Cu-Li Alloy 2195

Al-Cu-Li alloy 2195, with its combination of good cryogenic properties, low density, and high modulus, has been selected by NASA to be the main structural alloy of the Super Light Weight Tank (SLWT) for the Space Shuttle. Alloy 2195 is strengthened by an aging treatment that precipitates a particular precipitate, labeled as T1(Al2CuLi). Other phases, such as GP zone, (theta)', (theta)", theta, (delta)', S' are also present in this alloy when artificially aged. Cryogenic strength and fracture toughness are critical to the -SLWT application, since the SLWT will house liquid oxygen and hydrogen. Motivation for the Time-Temperature-Precipitation (TTP) study at lower temperature (lower than 350 F) comes in part from a recent study by Chen, The study found that the cryogenic fracture toughness of alloy 2195 is greatly influenced by the phases present in the matrix and subgrain boundaries. Therefore, the understanding of TTP behavior can help develop a guideline to select appropriate heat treatment conditions for the desirable applications. The study of TTP behavior at higher temperature (400 to 1000 F) was prompted by the fact that the SLWT requires a welded construction. Heat conduction from the weld pool affects the microstructure in the heat-affected zone (HAZ), which leads to changes in the mechanical properties. Furthermore, the SLWT may need repair welding for more than one time and any additional thermal cycles will increase precipitate instability and promote phase transformation. As a result considerable changes in HAZ microstructure and mechanical properties are expected during the construction of the SLWT. Therefore, the TTP diagrams can serve to understand the thermal history of the alloy by analyzing the welded microstructure. In the case welding, the effects of thermal cycles on the microstructure and mechanical properties can be predicted with the aid of the TTP diagrams. The 2195 alloy (nominally Al + 4 pct Cu + 1 pct Li + 0.3 pct Ag + 0.3 pct Mg + 0.1 pct Zr) used in this study was received in the form of 1.7 inch thick rolled plates. In brief goal of this study is to develop TTR diagram for the solutiontreated and stretched alloy 2195 from which the precipitation sequence at any service or aging conditions can be preducted.A subgrain boundary TTR diagram is also presented since precipitations at subgrain boundary can control and/or modify a wide veriety of material properties, such as cryogenic fracture toughness.

Chen, P. S.↗

NASA NTRS2002

Time-Temperature-Precipitation Behavior in Al-Li Alloy 2195

Transmission electron microscopy was used to study time-temperature-precipitation (TTP) behavior in aluminum-lithium (Al-Li) 2195 alloy. Al-Li 2195 (nominally Al + 4 percent Cu + 1 percent Li + 0.3 percent Ag + 0.3 percent Mg + 0.1 percent Zr) was initially solutionized for 1 hr at 950 F and then stretched 3 percent. Heat treatments were conducted for up to 100 hr at temperatures ranging from 200 to 1,000 F. TTP diagrams were determined for both matrix and subgrain boundaries. Depending upon heat treatment conditions, precipitate phases (such as GP zone, theta'', theta', theta, delta', T1, TB, and T2) were found in the alloy. The TTP diagrams were applied as a guide to avoid T1 precipitation at subgrain boundaries, as part of an effort to improve the alloy's cryogenic fracture toughness (CFT). New understanding of TTP behavior was instrumental in the development of a two-step artificial aging treatment that significantly enhanced CFT in Al-Li 2195.

Chen, P. S.↗

NASA NTRS1984

Creep-rupture reliability analysis

A probabilistic approach to the correlation and extrapolation of creep-rupture data is presented. Time temperature parameters (TTP) are used to correlate the data, and an analytical expression for the master curve is developed. The expression provides a simple model for the statistical distribution of strength and fits neatly into a probabilistic design format. The analysis focuses on the Larson-Miller and on the Manson-Haferd parameters, but it can be applied to any of the TTP's. A method is developed for evaluating material dependent constants for TTP's. It is shown that optimized constants can provide a significant improvement in the correlation of the data, thereby reducing modelling error. Attempts were made to quantify the performance of the proposed method in predicting long term behavior. Uncertainty in predicting long term behavior from short term tests was derived for several sets of data. Examples are presented which illustrate the theory and demonstrate the application of state of the art reliability methods to the design of components under creep.

Peralta-Duran, A.↗

NASA NTRS1985

Creep-rupture reliability analysis

Peralta-Duran, A.↗

NASA NTRS1991

Overview of the Telescience Testbed Program

The NASA's Telescience Testbed Program (TTP) conducted by the Ames Research Center is described with particular attention to the objectives, the approach used to achieve these objectives, and the expected benefits of the program. The goal of the TTP is to gain operational experience for the Space Station Freedom and the Earth Observing System programs, using ground testbeds, and to define the information and communication systems requirements for the development and operation of these programs. The results of TTP are expected to include the requirements for the remote coaching, command and control, monitoring and maintenance, payload design, and operations management. In addition, requirements for technologies such as workstations, software, video, automation, data management, and networking will be defined.

Rasmussen, Daryl N.↗

NASA NTRS1994

Time-to-Passage Judgments under Violations of Various Constancy Assumptions

Time-to-passage (TTP) derivations typically assume constant translational velocities and consistent object orientation. In our first study, we examined the impact of acceleration, and observer roll and heading (relative to track vector) on TTP judgments. Judgments reflected an insensitivity to acceleration; roll did not affect performance, but the decoupling of observer heading and track vector did. Our second study examined the effect of multi-axis target rotation on TTP and time-to-contact judgments.

Kaiser, Mary K.↗

NASA NTRS2019

Airspace Technology Demonstration 2 (ATD-2) Phase 2 Technology Description Document (TDD)

This Technology Description Document (TDD) provides an overview of the technology for the Phase 1 Baseline and Phase 2 Fused demonstrations of the Integrated Arrival, Departure, and Surface (IADS) prototype system of the National Aeronautics and Space Administration’s (NASA) Airspace Technology Demonstration 2 (ATD-2) project, which has been demonstrated since October of 2017 at Charlotte Douglas International Airport (CLT). Development, integration, and field demonstration of relevant technologies of the IADS system directly address recommendations made by the Next Generation Air Transportation System (NextGen) Integration Working Group (NIWG) on Surface and Data Sharing and the Surface Collaborative Decision Making (Surface CDM) concept of operations developed jointly by the Federal Aviation Administration (FAA) and aviation industry partners. NASA has been developing the IADS traffic management system under the ATD-2 project in coordination with the FAA, flight operators, CLT airport operators, and the National Air Traffic Controllers Association (NATCA). The primary goal of ATD-2 is to improve the predictability and operational efficiency of the air traffic system in metroplex environments, through the enhancement, development, and integration of the nation’s most advanced and sophisticated arrival, departure, and surface prediction, scheduling, and management systems. The ATD-2 project is a 5-year research activity beginning in 2015 and extending through 2020. The Phase 1 Baseline IADS capability resulting from the ATD-2 research has been demonstrated at the CLT airport since the beginning of October 2017. Phase 1 provided data exchange and integration with the initial demonstration of the integrated system of strategic and tactical scheduling, collaborative tactical surface metering, tactical departure scheduling to an en route meter point and overhead stream insertion, initial integration of a TFDM SWIM prototype feed, and an early implementation prototype of a Terminal Flight Data Manager (TFDM) Electronic Flight Data (EFD) system. The strategic surface scheduling element of the capability is consistent with the Surface CDM Concept of Operations published in 2014 by the FAA Surface Operations Directorate.1 The Phase 2 Fused IADS system provided substantial updates to baseline IADS Demonstration capability. Improvements were made to the IADS modeler; tactical surface scheduling, and metering; tactical departure scheduling for overhead stream insertion; Electronic Flight Data (EFD) and the integration with the FAA Advanced Electronic Flight Strip (AEFS); RTC/RMTC, and departure trajectories. New capabilities included a TFDM SWIM prototype feed and delivery of IADS data via the TFDM Terminal Publication (TTP) service of the FAA’s SWIM system; strategic surface scheduling and metering as well as fusion with tactical surface metering; integration and ingestion of data from TTP-connected Mobile App and texting industry for General Aviation (GA) flights; and expansion of airspace deployments to include adjacent Center automation, in particular interface with the Atlanta Center (ZTL) arrival metering TBFM system to evaluate pre-scheduling of flights. Improvements in Data Analysis and System Health (DASH) monitoring and updates were completed as well.

Talebi, Ehsan↗

NASA NTRS1992

Telescience Testbed Program: A study of software for SIRTF instrument control

As a continued element in the Telescience Testbed Program (TTP), the University of Arizona Steward Observatory and the Electrical and Computer Engineering Department (ECE) jointly developed a testbed to evaluate the Operations and Science Instrument System (OASIS) software package for remote control of an instrument for the Space Infrared Telescope Facility (SIRTF). SIRTF is a cryogenically-cooled telescope with three focal plane instruments that will be the infrared element of NASA's Great Observatory series. The anticipated launch date for SIRTF is currently 2001. Because of the complexity of the SIRTF mission, it was not expected that the OASIS package would be suitable for instrument control in the flight situation, however, its possible use as a common interface during the early development and ground test phases of the project was considered. The OASIS package, developed at the University of Colorado for control of the Solar Mesosphere Explorer (SME) satellite, serves as an interface between the operator and the remote instrument which is connected via a network. OASIS provides a rudimentary windowing system as well as support for standard spacecraft communications protocols. The experiment performed all of the functions required of the MIPS simulation program. Remote control of the instrument was demonstrated but found to be inappropriate for SIRTF at this time for the following reasons: (1) programming interface is too difficult; (2) significant computer resources were required to run OASIS; (3) the communications interface is too complicated; (4) response time was slow; and (5) quicklook of image data was not possible.

Young, Erick T.↗