Building consistent local submaps with omnidirectional SLAM

Autonomous and safe robot navigation requires the capability to simultaneously building a map of the environment and a selflocalization of the robot itself. This is known as the SLAM (Simultaneous Localization and Mapping) problem. In such a context, omnidirectional camera looks like a very interesting sensor since it allows a full 360 degrees field of vision. Complexity of the SLAM methods dramatically increases when the size of the environment grows up. Conversely, accuracy and integrity of the estimation process cannot be guaranteed any more. In this paper, we present an efficient way to reduce the complexity of the algorithms thanks to the definition of local submaps. In contrast with other papers dealing with local maps, our main purpose is not only to reduce the computational cost but also to keep the global map correlated. A method to consistently share information between local maps is also provided. These methods are used in the context of the omnidirectional bearing-only SLAM. Due to the specificity of the model of projection, images provided by the omnidirectional cameras cannot be used in a SLAM method without taking some precaution. In this paper, we provide an original method for computing the covariance matrix taking into account this specificity. Finally, we provide a validation with real data in an indoor environment subject to large illumination changes.