Stochastic perturbation analysis of computer control systems subject to electromagnetic disturbances

High intensity electromagnetic radiation has been demonstrated to be a source of computer upsets in commercially available digital flight control systems. Thus, there is a strong need to investigate its effect on stability and performance. In the authors´ previous works (1998, 1999), electromagnetic disturbances were modeled with a continuous-time Markovian exosystem generating disturbance events. To analyze the effect of these disturbances, the radiated system was modeled as a discrete-time jump linear system with an appropriate set of transition probability rates. The linear systems in this model were all deterministic, hence this method rendered a worst-case stability analysis. In this paper, the technique is generalized by allowing stochastic perturbations to be randomly introduced by the exosystem model. A preliminary stability theory is developed, and an example is presented to compare stability boundaries for radiation parameters using this model against the worst-case scenario.