Active laser radar for high-performance measurements

Abstract

Laser scanners, or laser radars (ladar), have been used for a number of years for mobile robot navigation and inspection tasks. Although previous scanners were sufficient for low speed applications, they often did not have the range or angular resolution necessary for mapping at the long distances. Many also did not provide an ample field of view with high accuracy and high precision. In this paper we will present the development of state-ofthe-art, high speed, high accuracy, 3D laser radar technology. This work has been a joint effort between CMU and K2T and Z+F. The scanner mechanism provides an unobstructed 360°horizontal field of view, and a 70°vertical field of view, Resolution of the scanner is variable with a maximum resolution of approximately 0.06 degrees per pixel in both azimuth and elevation, The laser is amplitude-modulated, continuous-wave with an ambiguity interval of 52m, a range resolution of 1.6mm, and a maximum pixel rate of 625kHz. This paper will focus on the design and performance of the laser radar and will discuss several potential applications for the technology. It reports on performance data of the system including noise, drift over time, precision, and accuracy with measurements. Influences of ambient light, surface material of the target and ambient temperature for range accuracy are discussed. Example data of applications will be shown and improvements will also be discussed.

Measurement quality metrics for rapid laser range scanning

“…The quality of a laser range scanner measurement depends on measurement uncertainty and measurement resolution; however, spatial uncertainty is also strongly affected by other environmental factors such as the type of surface material, 5 surface reflectivity, 6 distance to the surface, 6,7 and incidence angle. 8 The purpose of a quality metric is to quantify some aspect of the quality of a laser range scanner measurement with respect to some previously established benchmark.…”

Adaptive Laser Range Scanning using Quality Metrics

“…The quality of a range measurement depends on measurement uncertainty and measurement resolution; however, spatial uncertainty is also strongly affected by other environmental factors such as the type of surface material [6], surface reflectivity [7], distance to the surface [7] [8], and incidence angle [9]. These environmental conditions must be detected in the data and combined with model-based uncertainty as metrics that further describe the quality of the virtual model.…”

Large data sets and confusing scenes in 3-D surface matching and recognition

“…The Ben Franklin 2 (BF2), a scanning laser range finder mounted on Navlab 2 and Navlab 5, two of Carnegie Mellon University's (CMU's) autonomous ground vehicles, produces 360 degree by 30 degree range and reflectance images in a radius of 52 meters (Figure 8.) [12].…”