Experimental And Modeling Study Of Ant Herding Moving Rules

With the development of social economy and improvement of living standard, there are more and more huge buildings. Furthermore, there exist many high density areas of humans due to the increasing of population. Therefore, when disasters and accidents happen, it is a issue worth to studying how humans evacuate from the buildings in safety as soon as possible. Nevertheless, it still remains problems cannot be solved by using previous methods. For example, the validation of the evacuation model, the difficulty of conducting human evacuation experiments in panic, the lack of complete data from accident investigation and so on. Then some researches propose a new research method, that is animal experiment.In this paper, we regarded ants as the object of our study and investigated the behavior features of ants escaping the single-file passageway, rectangle room with single-exit and two-exit systematically under stress conditions. The characteristics of ants moving behavior in the evacuation process were investigated in detail and compared with those of human evacuation in order to further understand ants’moving behavior features, similarities and differences between behaviors of ants and humans, and explore a new method to investigate pedestrian evacuation.Firstly, the ant Camponotus japonicus was chosen as the study animal. We conducted ant evacuation experiments in a single-file passageway to show the movement characteristics of ants, common social insects, under stress conditions. In our experiments, citronella oil was used to elicit ant movement from one end of a unidirectional passage to the other. The movements were recorded with a video camera, and the speed and distance travelled were extracted using image processing. Surprisingly, the results differed from the human fundamental diagrams, that flow rate increased with density increasing and speed varied non-monotonically but had its own rules with increasing density. Our work may provide important insights into understanding swarm intelligence and provides experimental data on ant traffic.In order to further understand the ants moving features, we conducted experiments of Camponotus japonicus evacuating from a rectangle room with single exit. For these experiments, ants were placed inside a rectangular chamber with a single exit that also contained a filter paper soaked in citronella oil, a powerful repellent. The ants formed several groups as they moved toward the exit to escape. We measured the time intervals between individual escapes in six versions of the experiment, each containing an exit of a different width, to quantify the movement of the groups. As the ants exited the chamber, the time intervals between individual escapes changed and the frequency distribution of the time intervals exhibited exponential decay. We also investigated the relationship between the number of ants in a group and the group flow rate. Based on the data gathered from our ants evacuation experiments, "selfish evacuation behavior" was not observed in the ants experiments under stress conditions. To extend our understanding of the topic, we constructed a cellular automaton model to simulate the behaviors of ants in stress situations. Ant body size, shape, and actual speed gathered from previous ants evacuation experiments, were taken into account in our model. In previous ants experiment of our work, a filter paper with the repellent substance was located on the opposite side of the experimental chamber from the exit. Inspired by this experiment, parameter D was introduced in our model, which represented the drift to move forward (toward the exit, away from the repellent substance). Every ant (An) in the room had the same D value. In our model, N ants were initially distributed randomly in the room and the sequential update rule was adopted. Considering of the temporal evolution of the number of ants escaping within each exit size, we presented experimental result of each exit width and used our model to simulate ants escaping through that exit width several times. Subsequently, some factors affecting evacuation efficiency were also studied.Subsequently, in order to investigate the effect of the distance between two exits on ant evacuation efficiency and the behavior of ants escaping from a two-exit room, we conducted ant egress experiments using Camponotus japonicus in multiple situations. We found that the ants demonstrated the phenomenon of "symmetry breaking" in this stress situation. It was also shown that different locations for the exits obviously affected the ants’egress efficiency by measuring the time intervals between individual egress and flow rate in eight repeated experiments, each of which contained five different distance between the two exits. In addition, it is demonstrated that there are differences between the predictions of Social Force Model of pedestrians and the behaviors of ants in stress conditions through comparing some important behavioral features, including position, trajectory, velocity, and density map.In addition, we carried out experimental research on "blind" people. In our study, different from previous researches, we studied characteristics of pedestrian behaviors within different widths of one exit, different locations of two exits and also enlarged the room size and number of pedestrians. We focused on the bunch-forming phenomenon and human’s behavior without visibility. The evacuation process was observed and recorded by video cameras. Different from the people with visibility, blindfolded people showed a typical behavior. During the evacuation, the flow of people was discovered divided into several bunches. Based on the video observation and data statistics, it is found that no jamming through exit and even the density near the exit reaches 3.29 people/m2. Study on the people movement shows that the velocity of blindfolded people obeys Gaussian distribution. In addition, the evacuation in a two exits room is more effective when two alternative exits are used more approximately. Furthermore, it is found that there are some similarities between the "blind" people and ants behaviors in evacuation experiments.In the end, we summarized all the research works and main results, and also propose the further research works in the future based on the present works.