Corresponding author: Stepanov Dmitry N., Head of Computer Vision Laboratory, Institute for Robotics and Technical Cybernetics, St. Petersburg, Russia, 194064
e-mail: dnstepanov@rtc.ru

Accepted on August 07, 2017

The article presents an approach to using of visual location of an arbitrary number of known natural landmarks for correction of position estimation of a mobile robot. The approach is based on using of the Extended Kalman Filter to perform steps of the position prediction and correction based on the visual location. The visual location is performed using a calibrated camera (or a set of cameras) installed on the mobile robot. The task of a mobile robot navigation in a case of poorly determined conditions is often soled using a set of expensive LIDARs. Other sensors like GNSS and odometer often used in mobile robots are usually not precise enough (for example when maneuvering on intersections). The recent research in the field of computer vision allows creation of much less expensive systems based on image analysis from one or several cameras. When used together with other sensors such system can significantly increase the navigation precision and stability. Known visual navigation approaches like visual SLAM and visual odometer are often used but they are often not precise enough especially when the camera move­ment is mostly rotating. A set of one or more natural visual landmarks can be located automatically in real time using mobile robot cameras. Existing methods provide partial solutions for the position or direction estimation using 3 or more landmarks. The proposed approach is based on using of the Extended Kalman Filter for efficient fusion of the odometer and GNSS data with the visual location of one or more landmarks. Since all the landmarks are used one at a time independently the number of landmarks, cameras, their types and positions are arbitrary. The method is working with one camera and one landmark as well as with a round view camera system with one or many landmarks. Experiments involving autonomous driving through different intersections shown the feasibility of reaching of the accuracy of horizontal position of 10 cm and rotation of 1° and below. The method has been developed for improving of unmanned vehicles navigation at intersections but can be applied to navigation of different ground, space, marine and underwater mobile robots.
Keywords: mobile robot, unmanned ground vehicle, visual navigation, visual location, computer vision, Kalman filter, sensor fusion