Advanced Guidance and Control for Hypersonics and Space Access
Advanced guidance and control (AGC application to hypersonic air-breathers is planned. We list the test cases used to demonstrate that the desired results are achieved, briefly describe an automated test scoring method, and display results of the tests. Some of the technology components have reached the maturity level where they are ready for application to a new vehicle concept, while others are not far along in development.
Reusable launch vehicle attitude control using a time-varying sliding mode control technique
We present a time-varying sliding mode control (TVSMC) technique for reusable launch vehicle (RLV) attitude control in ascent and entry flight phases. In ascent flight the guidance commands Euler roll, pitch and yaw angles, and in entry flight it commands the aerodynamic angles of bank, attack and sideslip. The controller employs a body rate inner loop and the attitude outer loop, which are separated in time-scale by the singular perturbation principle. The novelty of the TVSMC is that both the sliding surface and the boundary layer dynamics can be varied in real time using the PD-eigenvalue assignment technique. This salient feature is used to cope with control command saturation and integrator windup in the presence of severe disturbance or control effector failure, which enhances the robustness and fault tolerance of the controller.
Shuttle automatic landing system
The Shuttle automatic landing system design requirements are discussed, the approach and landing flight phase is described, and the hardware and software subsystems are functionally described. Emphasis is placed on the complexity, flexibility, and criticality of the software function. The software structure, critical computational problems, and verification process as a subsystem are discussed. Finally, the hardware/software verification activities required before flight test of the autoland system are described, along with the results from two flight tests and the planned system certification to the operational flight boundaries.