Features detection of the environment. Line segment and corner detection by a mobile robot. a) The robot and the detected corner show the covariance ellipse associated to them. b) Detection of line and a corner. Both features, the lines and corners, represent the environment through which the mobile robot navigates. The parameters of both features correspond to the ones shown in Eqs. (8) and (9): ρ is the distance of the line to the origin of the coordinate system and α the angle between the x--axis and a normal to that line; on the other hand, Z
is the distance of the robot to the corner and Z
is the angle between the x--axis of the robot and the corner.