The AIS 3D Laser Range Finder

The AIS 3D laser range finder (Figure 1, top right) [17,16] is built on the basis of a 2D range finder by extension with a mount and a standard servo motor. The 2D laser range finder is attached in the center of rotation to the mount for achieving a controlled pitch motion. The servo is connected on the left side (Figure 1, top middle). 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) on one battery pack.

Figure 1: Top left: The autonomous mobile robot Kurt3D equipped with the 3D scanner. Top right: The AIS 3D laser range finder. Its technical basis is a SICK 2D laser range finder (LMS-200). Bottom row, left: A scanned scene as depth image. Middle and right: Scanned scenes as point cloud viewed with a camera orientation towards the door.

The area of $180^{\circ}$(h)$\times 120^{\circ}$(v) is scanned with different horizontal (181, 361, 721 pts.) and vertical (210, 420 pts.) 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, double or quadruple this time. Thus, a scan with 181 $\times$ 210 data points needs 2.8 seconds. In addition to the distance measurement, the 3D laser range finder is capable of quantifying the amount of light returning to the scanner, i.e., reflectance data [14]. Figure 1 (bottom left) shows a scanned scene as depth image, created by off-screen rendering from the 3D data points (Figure 1, bottom middle) by an OpenGL-based drawing module.