The AIS 3D Laser Range Finder

The AIS 3D laser range finder (23) is built on the basis of a 2D range finder by extension with a mount and a servomotor. The 2D laser range finder is attached to the mount for being rotated. The rotation axis is horizontal. A standard servo is connected on the left side (figure 1) and is controlled by the computer running RT-Linux, a real-time operating system which runs LINUX as a task with lowest priority (23). The 3D laser scanner operates up to 5h (Scanner: 17 W, 20 NiMH cells with a capacity of 4500 mAh, Servo: 0.85 W, 4.5 V with batteries of 4500 mAh).

Figure 1: The AIS 3D laser range finder.

The area of $180^{\circ}$(h)$\times 120^{\circ}$(v) is scanned with different horizontal (181, 361, 721) and vertical (128, 256) resolutions. A plane with 181 data points is scanned in 13 ms by the 2D laser range finder (rotating mirror device). Planes with more data points, e.g., 361, 721, duplicate or quadruplicate this time. Thus a scan with 181 $\times$ 256 data points needs 3.4 seconds. In addition to the distance measurement the AIS 3D laser range finder is capable of quantifying the amount of light returning to the scanner.