Using role-based control to produce locomotion in chain-type self-reconfigurable robots

This paper presents a role-based approach to the problem of controlling locomotion of chain-type self-reconfigurable robots. In role-based control, all modules are controlled by identical controllers. Each controller consists of several playable roles and a role-selection mechanism. A role represents the motion of a module and how it synchronizes with connected modules. A controller selects which role to play depending on the local configuration of the module and the roles being played by connected modules. We use role-based control to implement a sidewinder and a caterpillar gait in the CONRO self-reconfigurable robot. The robot is made from up to nine modules connected in a chain. We show that the locomotion speed of the caterpillar gait is constant even with loss of 75% of the communication signals. Furthermore, we show that the speed of the caterpillar gait decreases gracefully with a decreased number of modules. We also implement a quadruped gait and show that without changing the controller the robot can be extended with an extra pair of legs and produce a hexapod gait. Based on these experiments, we conclude that role-based control is robust to signal loss, scales with an increased number of modules, and is a simple approach to the control of locomotion of chain-type self-reconfigurable robots.