Selection of the collision avoidance maneuver by the areas of points of its allowable initiatives

A method, that in the dialogue mode with the collision avoidance system simplifies the determination of Z-maneuver for safe passing by the ships, is proposed in the article. The maneuver is selected by using the zones of its allowable initiations that are displayed in this system on the screen periphery. It ensures the absence of these zones in the bow sector, distinguished for control of safety of situation ahead of own ship, and it eliminates shading and masking of navigation-important objects by these zones. When considering the task, it is assumed that course changes are performed with a rudder angle of 150, that the turning ability of the own vessel to the right and left is the same and the turning path is an arc of a circle with a radius that correspond to the rudder angle. When calculating the Z-maneuver, the curvilinear sections of the trajectory are replaced by time-equivalent straight segments of uniform motion. The diagram, that facilitates the maneuver selection, represents a set of safe beginnings of this action in relation to all targets, taken into account when solving the collision avoidance problem. The values of the course changes are plotted along horizontal axis of this diagram, and the distances to the boundary of own ship advance actions in relation to the most dangerous target are put aside its vertical axis. The main part of the proposed method is the procedure for finding the intervals of acceptable initiations of course alteration for avoiding collision with one ship and segments of safe returning to the previous course for Z-maneuver with a given value of the angle of deviation from the original course. In order to obtain more complete information about the set of permissible maneuver variants it is possible to display the indexes of theirs effectiveness at the top of a diagram. The reliability of obtained results was confirmed by simulation modeling of the collision avoidance processes on a computer. For this purpose a special program was drawn up. One example of such examination is given in the article. The advantage of the proposed method to avoid collision is the possibility of simultaneous selection of the beginning and magnitude of the course change, the point of safe return to the initial course in the evasion segment, and the absence of graphical elements, that facilitate the choice of maneuver, on the system screen in a zone for navigation safety control.