Vehicular trajectory collision conflict prediction method
First Claim
1. A method for determining a collision probability between a subject object and a target object, the method comprising the steps of,propagating initial positions and initial velocities and initial error covariances of the subject object and the target object over a propagated trajectory duration having propagated trajectory time steps for providing respective propagated positions and propagated velocities and propagated error covariances in respective initial reference frames, transforming the propagated error covariances of the target object and subject object into scaled error covariances in a scaled reference frame for each of the propagated trajectory time steps, transforming the propagated positions and propagated velocities and a conflict volume into scaled positions and scaled velocities and scaled conflict volume in the scaled reference frame, the scaled velocities are relative velocities between the subject object and target object, aligning the scaled positions and scaled velocities and scaled error covariances and scaled conflict volume into an encounter reference frame having an encounter plane orthogonal to the relative velocities, the scaled conflict volume becoming a keep-out box in the encounter plane, and computing a conflict probability using contour integration over an integration path about the keep-out box and over a probability density.
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Abstract
A collision prediction and maneuver method determines which ones of many potential target objects have a close conjunction within a gross miss distance with a subject object by trajectory propagation, then determines which one of the conjunctive objects have a high collision probability within a critical miss distance, and then determines an optimum vehicle maneuver to reduce the probability of colliding with another colliding object by determining the maneuver direction, magnitude, and time so that the least amount of propellant is consumed while avoiding potential collisions within miss distance margins. The method includes computational efficiencies in collision probability calculations using trajectory propagations and contour integrations and efficiencies in optimum avoidance maneuvering using gradient and searching computations.
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13 Claims
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1. A method for determining a collision probability between a subject object and a target object, the method comprising the steps of,
propagating initial positions and initial velocities and initial error covariances of the subject object and the target object over a propagated trajectory duration having propagated trajectory time steps for providing respective propagated positions and propagated velocities and propagated error covariances in respective initial reference frames, transforming the propagated error covariances of the target object and subject object into scaled error covariances in a scaled reference frame for each of the propagated trajectory time steps, transforming the propagated positions and propagated velocities and a conflict volume into scaled positions and scaled velocities and scaled conflict volume in the scaled reference frame, the scaled velocities are relative velocities between the subject object and target object, aligning the scaled positions and scaled velocities and scaled error covariances and scaled conflict volume into an encounter reference frame having an encounter plane orthogonal to the relative velocities, the scaled conflict volume becoming a keep-out box in the encounter plane, and computing a conflict probability using contour integration over an integration path about the keep-out box and over a probability density.
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