Group Coordinated Control of Networked Mobile Robots With Applications to Object Transportation

Inspired by the group activities of natural swarms (e.g., a flock of birds, a colony of ants, etc.), a fleet of mobile robots can be collaboratively put into work to accomplish complex real-world tasks. Depending on the nature and complexity of a problem, a multi-robot system (MRS) may need to be decomposed into several subgroups. This paper proposes a unified group coordinated control scheme for networked MRSs having multiple targets. A 'discontinuous' cooperative control law is first developed for a networked MRS to achieve individual sub-formations surrounding the assigned targets. A 'continuous' cooperative control protocol is then proposed to overcome the chattering phenomenon often caused by a discontinuous control action during hardware implementation. The closed-loop stability of the overall networked MRS is guaranteed via the Lyapunov theory and boundary-layer techniques. Finally, two hardware experiments (target-enclosing and object transportation) involving real mobile robots have been carried out to demonstrate the usefulness of the proposed scheme.