Closed-Loop Performance Measures for Flight Controllers Subject to Neutron-Induced Upsets

veloped with the general goal of quantifying the nature of the risk and to produce guidelines for the aerospace industry and chip manufacturers. A set of experiments is underway at the Los Alamos Neutron Science Center (LANSCE) in Los Alamos, New Mexico to provide data [9]. While a variety of different technologies will be tested, our interest here is specifically on an experimental Recoverable Computer System (RCS) developed by Honeywell, Inc. Its error recovery system is implemented using multiple dual-lock-step processors together with new fault tolerant architectures and communication subsystems [7, 8]. The error recovery technique implemented on the RCS is a variation of rollback recovery [12, 15]; it has the following steps: It has been observed that atmospheric neutrons can produce single event upsets in digital flight control hardware. The phenomenon has been studied extensively at the chip level, and now system level experiments are underway. In this paper analytical closedloop performance measures for the tracking error are developed for a plant that is stabilized by a recoverable computer system subject to neutron induced upsets. The underlying model is a Markov jump-linear system with process noise. The steady-state tracking error is expressed in terms of a generalized observability Gramian.