Effect of Assailants on Crowd Evacuation: A Fuzzy Logic Approach

Modeling and analyzing crowds´ behaviors and characteristics in an emergency are a useful and challenging work. In this paper, a fuzzy logic approach is proposed to describe crowd evacuation behaviors under the effect of assailants. Firstly, different kinds of fuzzy logic models are proposed according to different intentions of assailants and pedestrians. Pedestrians are further divided into three categories based on their surrounding environment. Individual´s behaviors are determined by fusing of recommendations of local avoid-obstacle behavior, regional search-path behavior and global seek-goal behavior with adjustable weighting factors, which are adjusted by the perceptual information obtained from interaction with environments in the visual field. Simulations in a hall with a single exit have been implemented. It is shown that the variation of the model parameters such as pedestrians´ speed, assailants´s speed, duration of attack and so on greatly influences the evacuation efficiency. In addition, a novel "circuity phenomenon" that pedestrians give up the direction of goal when their saw assailants and faced a very crowded exit are observed in crowd evacuation simulations.