Conflict Detection Concepts for Wake Encounter Prevention, Improvements of FLYSAFE Conflict Detection Algorithm, SubWEPS Task 3.1 - Development of 4D wake encounter conflict detection concept and algorithm

Kurzfassung

Within the scope of the project SubWEPS in Task 3.1 an existing algorithm for conflict detection between an aircraft's predicted flight path and wake vortex hazard volumes (called wake segments) was analysed and improved. Four different concepts for conflict detection algorithms applicable to wake vortex volumes (from literature or newly developed) have been investigated and compared. The analysis revealed that an improved FLYSAFE method is the best choice in view of the requirements (real-time capability, numerical stability, algorithmic complexity, discretisation error and memory requirements in order of decreasing relevance). Functional improvements have been made so that the wake segments of the probable wake vortex area, each defined by two wake elements, can now be orientated in all six degrees of freedom. The problems of contraction, which can occur in case of twisting wake elements, were solved by a dynamically adapting correction factor. Furthermore, considerations of characteristics of convex volumes led to improvements in terms of runtime of the algorithm. By simplifications of geometric calculations and introduction of criteria for terminations of the algrithm the number of necessary calculations could be significantly reduced. These optimisations led to a quicker and more precise conflict detection algorithm. For realisation and verification of those improvements, a prototype of the geometric core of the selected conflict detection algorithm was implemented in MATLAB to create a frame work with adaptable visualisation (which is not available in the Wake Encounter Prevention System WEPS). The verified algorithm was then implemented in C++ for the WEPS framework. A verification plan was set up and executed to ensure proper unit testing (verification of correct function of the algorithm) and integration testing (verification of correct integration into WEPS). The development framework will also be helpful for the following Task 3.2. Here, splitting of the hazard volume in ground effect and aircraft collision avoidance will be investigated.