REAL-TIME ACCOMMODATION OF ACTUATOR FAULTS ON A REUSABLE ROCKET ENGINE

An intelligent control system for reusable rocket engines is under dev elopment at the NASA Lewis Research Center, The primary objective is t o extend the useful life of a reusable rocket propulsion system while minimizing flight maintenance and maximizing engine life and performan ce through improved control and monitoring algorithms and additional s ensing and actuation, The main result of this work is the successful i ntegration and real-time demonstration of model-based fault detection with a reconfigurable control as a nem technique for valve fault accom modation on a reusable rocket engine. The fault detection scheme detec ts a variety of fault modes for a valve including freezing, limiting, and leakage, However, the focus here is on detecting and accommodating a frozen (stuck in a fixed position) oxidizer valve during a down-thr ust and up-thrust maneuver by examining fault parameters produced by t he algorithm, The valve is selected because of its critical role in re gulating the main combustion chamber mixture ratio (oxygen/fuel), The detection scheme estimates the position of the frozen valve as a funct ion of the fault parameters, A new thrust limit is computed based on t he position of the frozen valve and is used by the controller during t hrottling, Degraded thrust potential in a particular engine within an engine cluster can be managed at the propulsion level to meet mission requirements. Real-time simulation results demonstrate the effectivene ss of the approach for two fault scenarios during a typical throttling maneuver.