The objective of this research is to optimize robots cooperative work and obtain the minimum displacement of humans in a guiding people mission, where some individuals can escape from the formation and must be regrouped by robots. The guiding mission is done in an urban environment, with obstacles and building constraints, where people can move freely and using multiple mobile robots which work cooperatively. In this paper, the forces that actuate toward robots will be studied, which are the forces between robots and humans and the forces between humans. Our goal is to find out the minimum work required for robots to lead and regroup people. We have developed a cost function that minimizes the work required in order to do this cooperative task.