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.
Space Shuttle autoland design
The Orbiter Autoland system is activated at 10,000 ft altitude and performs energy control through speedbrake modulation, vertical path tracking with acceleration commands to the pitch control system, lateral path tracking through bank angle commands to the roll control system, and brings the vehicle to main gear touchdown. A nominal 19 degree glide slope is flown down to 2000 ft, followed by a 1.5 deg path to flare and subsequent soft landing. The flight path is similar to that which a pilot would fly, a feature which increases safety factors should manual takeover be necessary during landing maneuvers. A block diagram of the autoland control interfaces is provided, and attention is given to the use of a reference trajectory, the guidance laws, lateral guidance, the speed control system, pitch rate control, and the rollout system. Conditions and instrument indications leading to pilot takeover are outlined.
Decoupling of failed actuators in flight control systems
In this paper, an approach for predesigning controllers for a switching control scheme for systems undergoing actuator failures is proposed. Controller predesign for actuator failures is not trivial as the values at which the failed actuators freeze is not known a priori. The actuators failed at a nonzero position act as persistent disturbances significantly altering the system dynamics. The controller design in this paper is accomplished by using disturbance decoupling approach which ensures complete rejection of the disturbances caused by actuator failures in the steady state. The design is completed using linear quadratic control to address the transient response. The design procedure is demonstrated on a multiple actuator failure of an aircraft carrier landing system.