ORBITAL system: numerical evolution and first experimental results

We describe, in this paper, the hardware and software evolution of our "ORBITAL system" (one rotating beacon for information transmission and absolute localization). The main advantage of this system is that it only needs one active beacon for a complete localization of the mobile robot (2 Cartesian coordinates and the orientation). The receiver was made by an array of 6 large photodiodes (1 cm) fixed on the vehicle. The active beacon is a rotating laser, fixed on a wall of the maneuvering area, with vertical line generation lens. This beacon includes an innovative laser modulation, based on a frequency variation which is a function of its absolute angular position. In the first part, a short description of the first (analog) version of the beacon and receiver is made and the theoretical localization principle of this system is summarized. In the second part the problems generated by the use of analogue technology is described and the solution brought by the new numerical version of the beacon is explained. In the third part, the numerical approach is demonstrated to simplify the calibration procedure and error estimation calculations. The first results obtained in real conditions are given in the final part.