Behaviors for Physical Cooperation Between Robots for Mobility Improvement: Hardware Results and Use of Dynamics

A team of small, low-cost robots instead of a single large, complex robot is useful in operations such as search and rescue, urban exploration etc. However, the performance of such a team is limited due to the restricted mobility of the team members. This paper presents the results obtained toward the goal of enhancing mobility of a team of mobile robots by physical cooperation among the robots with the focus on the development of the low level system components. Recognizing that small robots need to overcome discrete obstacles, we develop specific analytical maneuvers to negotiate each obstacle where a maneuver is built from a sequence of fundamental cooperative behaviors. We have developed a 2-robot hardware system based on our idea of cooperative mobility improvement and guided by the results from the static analysis. We have demonstrated the implementation of basic cooperative behaviors, such as cooperative lift, and by implementing the decentralized control architecture we have demonstrated gap crossing maneuver with the hardware. We have analytically proved that robot dynamics can be used to reduce the friction requirements in the lift behavior and have demonstrated, with simulations, implementation of this idea for the cooperative lifting behavior