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A Virtual Spring Damper Method for Formation Control of the Multi Omni-directional Robots in Cooperative Transportation

This research reports the formation control method of multi holonomic robots for cooperative transportation. The proposed method is based on the concept of a virtual structure. There are virtual springs and dampers link between the virtual leader (VL) and follower robots. With the virtual spring and damper forces, a group of robots can follow the VL while keeping the distance from the VL and other follower robots to avoid a collision among them. The algorithm required a predefined formation shape and size depend on a transport object. The proposed method was developed based on the Robot Operating System (ROS) and evaluated in the simulation software Gazebo. Two experiments were conducted by using the 3D model of our Mecanum wheel robot platform. In the first experiment, the four follower robots can aggregate to the position of the VL to form a diamond shape formation. In the second experiment, a group of follower robots with an object on their bodies can maintain a formation while following the VL along a predefined trajectory. The simulation results confirm that the method proposed in this paper is feasible for the cooperative transportation task.