ATED Navigation Flight Software Experiment and Real-Time Test Bed
ATK (Alliant TechSystems) a producer of solid rocket motor products and technologies initiated a program to leverage key strengths into a low-cost solution for orbital access. As a first step, ATK set out to piggy-back a qualified flight processor, capable of navigation and telemetry, on board a NASA sounding rocket. The program was named ATED (Advanced Solid Axial Stage Technology Evaluation and Demonstration).
The program represented a tall technical navigational challenge of tracking the rocket attitude that was to be spin-stabilized at a spin rate of 4 Hz. Additionally, in order to be competitive in the demanding market of expendable launch vehicles such capability had to be attained while cost and development time was minimized.
ATK hired real-time flight software experts at ATA to produce the navigation flight software, on-board operating system, EGSE (Electronic Ground Support Equipment used for pre-flight system check-out and flight software initialization) and real-time hardware-in-the-loop 6 Degree-of-Freedom test bed used to test the Navigation flight software. All of the above had to be completed within just eight months.
In order to meet the challenge of high-accuracy state vector tracking, along with condensed schedules and budgets, ATA leveraged two key resources: the National Instruments LabVIEW Real-Time Module, and the ATA Aerospace Toolkit for LabVIEW. Use of the LabVIEW Real-Time Module was a fast and efficient method for interfacing the processor with the simulated flight environment for the 6 DOF test bed. Use of the ATA Aerospace Toolkit provided access to pre-tested, high-fidelity, software for modeling all aspect of flight dynamics.
To create the simulated flight environment engineers used the mathematical libraries from the ATA Aerospace Toolkit for performing manipulations of quaternions, vectors, and matrices, and for numerical integration, as well as its gravitational models. The Toolkit's geodetic models were needed for mapping the vehicle trajectory relative to the Earth. This, Coupled with NIís LabVIEW Real-Time Module, enabled ATA engineers to assembled a 6DOF real-time, hardware-in-the-loop test bed for testing the on-board operating system and navigation flight software, all operating in a very complex aerodynamic and vehicle dynamic environment. The ATA Aerospace Toolkit also provided the basic functionality for configuring the navigational flight software for tackling the very complex problem of tracking the vehicle state of a sounding rocket along itís 10 minute trajectory while spinning at 4 Hz.
The ATED flight experiment was launched from Wallops Island on Tuesday, July 28, 2005. The real-time test bed was used to perform various flight software tests prior to launch in order to verify proper operation of the operating system and navigation flight software. The EGSE delivered performed extremely well in pre-flight checkout and initialization of the vehicle. The navigation flight software in conjunction with the operating system performed superbly. The navigation flight software predicted state agreed with post flight processed RADAR tracking data to well within 1 standard deviation. Careful analysis of the post flight processed telemetered navigation data revealed precession of the vehicle spin axis as predicted by pre-flight 6 DOF simulation.