ORBITAL system: Numerical evolution and first experimental results

We describe, in this paper, the hardware and software evolution of our "O.R.B.I.T.A.L system" (One Rotating Beacon for Information Transmission and Absolute Localization) [1]. The main advantage of this system is that it only need 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 (1cm) fixed on the vehicle. The active beacon is a rotating laser, fixed on a wall of the manoeuvring area, with vertical fine 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, we will make a short description of the first (analogical) version of the beacon and receiver and we will summarize the theoretical localization principle of this system. In the second part we will describe the problems generated by the use of analogue technology and will explain the solution brought by our new numerical version of the beacon. In the third part we will demonstrate how the numerical approach simplifies the calibration procedure and error estimation calculations. We will give the first results obtained in real conditions in the final part.