Time-varying patrolling scheme for multi-robots

The research of multi-robot surveillance has increasingly gained interest in recent years, mainly due to the possibility of security applications. In previous papers, multi-robot patrolling algorithms were focused on the minimization of time required to complete the patrolling of an entire area. However, these approaches of reducing time can overlook an important objective of patrolling such as preserving a certain level of overall security. This paper introduces the patrolling algorithm for multi-robot in the time-varying environment to maintain security at a safe level. The environment is represented in a graph with nodes for valuable places and shows links for paths between nodes. The safe level of nodes is measured by the function of time, the distance between robots and a node, and the existence of an intruder in a node. After the level of nodes is measured and when the node's security level is below “safe”, the patrolling robots move toward that node. As the evaluation of the patrolling algorithm, we considered the safe level distribution curve for each node and the average security level distribution curve.