Dynamic verification of a large discrete system [aircraft landing gear controller]

Symbolic algebraic analysis techniques are applied to the landing gear subsystem in the Swedish fighter aircraft, JAS 39 Gripen. Our methods are based on polynomials over finite fields (with Boolean algebra and propositional logic as special cases). Polynomials are used to represent the basic dynamic equations for the processes (controller and plant) as well as static properties of these. Temporal algebra (or temporal logic) is used to represent specifications of system behaviour. These specifications are verified both on a model of the landing gear controller, and a model of the closed loop behaviour of the landing gear controller connected to a plant. The model of the landing gear controller is made from the actual implementation in Pascal. The tools used are developed by the authors in Mathematica and uses an efficient implementation of binary decision diagrams