Angle-based methods for mobile robot navigation: Reaching the entire plane

Popular approaches for mobile robot navigation involve range information and metric maps of the workspace. For many sensors, however, such as cameras and wireless hardware, the angle between two features or beacons is easier to measure. With these sensors' features in mind, we initially present a control law, which allows a robot with an omni-directional sensor to reach a subset of the plane by monitoring the angles of only three landmarks. By analyzing the law's properties, a second law has been developed that reaches the complementary set of points. The two methods are then combined in a path planning framework that reaches any possible goal configuration in a planar obstacle-free workspace with three landmarks. The proposed framework could be used together with other techniques, such as obstacle avoidance and topological maps, to improve the efficiency of autonomous navigation. Experiments have been conducted on a robotic platform using a panoramic camera that exhibit the effectiveness and accuracy of the proposed techniques. This work provides evidence that navigational tasks can be performed using only a small number of primitive sensor cues and without the explicit computation of range information.