Finite Time Horizon State Synchronization of Asynchronous Flight Control Computers

In this paper, we propose a finite time horizon state synchronization strategy with the possibility to detect and mitigate asynchronous effects that would otherwise hinder the synchronization of two asynchronous flight control computers. This is especially relevant for redundant command and monitor flight control system architectures as they consist out of two independent computers. Different solutions to the synchronization problem are investigated using a previously developed simulation framework, and their benefits and drawbacks are highlighted. The necessary assumptions regarding execution times, asynchronous effects, scenarios and the minimum signal integrity are formulated, and their validity is justified. Requirements for the proposed finite time horizon state synchronization strategy are derived and validated with formal methods. Test results in the form of counter-examples that violate the requirements are presented and then used to improve the design. Lastly, the final strategy, including the detection and mitigation of asynchronous effects with two parameter sets for different signal characteristics, is presented.