Omnidirectional humanoid navigation in cluttered environments based on optical flow information

In this paper, we address the problem of humanoid navigation in a priori unknown environments, cluttered by obstacles. The robot task is to move within the environment without colliding with obstacles and using only ordinary on-board sensors, like monocular cameras and encoders. The proposed approach relies on: (i) optical flow information, to construct a local representation of the environment obstacles and free space; (ii) visual servoing techniques, to achieve safe motion within the environment while regulating appropriate visual features and the robot internal configuration. In case of navigation in a straight corridor, it can be formally proved that the robot converges to the corridor bisector. With respect to previous works, the algorithm proposed here does not make use of any information about the environment, and exploits the humanoid omnidirectional walking capability to achieve safe navigation in narrow passages. The approach is validated through simulations and experiments with NAO.