Scratch Team of Single-Rotor Robots and Decentralized Cooperative Transportation with Robot Failure

Achieving cooperative transportation by teams of aerial robots has been attracting attention owing to its flexibility with respect to payloads and robustness against failures. In this paper, we propose a flexible decentralized controller for the number of robots and the shapes of payloads in a cooperative transport task using multiple single-rotor robots. Our controller is robust to mass and center of mass fluctuations and robot failures. Moreover, asymptotic stability against dynamics errors is guaranteed. Additionally, the controller supports heterogeneous single-rotor robots. Thus, robots with different specifications and deterioration can be effectively utilized for cooperative transportation. In particular, this performance is effective for robot reuse. To achieve the aforementioned performance, the controller consists of a parallel structure comprising two controllers: a feedback controller, which renders the system strictly positive real, and nonlinear controller, which renders the object asymptotic to the target. First, we confirm cooperative transportation using 8 and 10 robots for two shapes via numerical simulation. Subsequently, the cooperative transportation of a rectangle payload (with a weight of approximately 3 kg and maximum length of 1.6 m) is demonstrated using a robot team consisting of three types of robots, even under robot failure and center of mass fluctuation.