Compliance control during cooperative transport using multiple mobile robots

In recent years, there has been concern over labor shortages. Robots are being introduced for transportation and other tasks. When robots are used in the environment with humans, it is desirable that the size is small and the output is relatively small from a viewpoint of safety. However, in the case of using one robot, there is a limit to the transport capacity. To address this issue, this paper describes the cooperative control of two mobile robots to realize the transportation ability that cannot be achieved by one robot. In the cooperative control, external force detection from the environment is important to enhance the adaptability of the robot. In the previous studies, force sensor was used for each robot, and it was possible to transport even when an external force is applied to the robot. However, the cost increases as the number of robots used increases. Therefore, this paper proposes compliance control that enables transport with reduced force fluctuation without external force sensor. Position control and sensorless force control are assigned to each robot, and when an external force is applied to sensorless force control robot, the control method is switched between the robots to realize the fluctuation suppression of the grasping force.