Calculation Method of Collision Probability for Airdroping Targets in Limited Space

Airdropping relief supplies to disaster-stricken areas is one of the most effective means to implement rapid supply after major natural disasters. Due to the relatively small key disaster-stricken areas, the collision of airdrop targets in a limited space will make it difficult for relief supplies to reach the rescue area accurately, thus losing the value of airdrop. Starting from the general form of collision probability, this paper studies three numerical calculations: direct solution, two-dimensional integral and one-dimensional integral by transforming the three-dimensional probability calculation problem into the two-dimensional probability calculation problem in the vertical encounter plane. Numerical examples show that the results of the two kinds of integrals are relatively close, and they can be used to calculate the collision probability of airdrop targets in most cases, and the one-dimensional integrals are more advantageous without considering the factor of calculation efficiency; Based on the condition that the projected area is circular and the probability density does not change much, the direct solution can also be used to calculate the collision probability in general cases, but compared with the two-dimensional integral and the one-dimensional integral, the maximum calculation error is about 2.74% and 2.97% respectively; The two-dimensional integral calculation can be used to calculate the collision probability in most cases, and the calculation accuracy is relatively high. When considering the calculation efficiency factor, the two-dimensional integral calculation can replace the one-dimensional integral calculation. The conclusion of the study can provide support for the implementation of active evasion strategy of airdrop targets.