John Laurent

Road surface inspection using laser scanners adapted for the high precision 3D measurements of large flat surfaces

In this paper an optical configuration based on autosynchronized laser scanning is proposed for the 3D measurement of road surfaces. The advantages of this technique over classical triangulation methods are exposed. The road inspection system developed at the National Optics Institute (NOI) using this type of laser telemetry is also presented. This system uses two autosynchronized laser scanners in order to obtain transverse 3D and intensity profiles of road surfaces. Also described are simple algorithms which detect and measure rutting and cracking conditions. Results include rut measurements on both real and simulated 3D road profiles and a crack map of an actual pavement section.

An Optical Tracked Hand-Held Range Sensor

In order to efficiently digitize the 3-D shape of objects in applications such as quality control, reverse engineering and inspection, a flexible system based on a portable range sensor coupled to an optical tracking device has been developed. The hand-held range sensor can be moved freely in space without the constraint on motion imposed by a translation or rotation system. An optical tracking device synchronized with the sensor is used to compute the sensors orientation and location in real-time. The optical tracking and the integration of a 3-D range sensor with a positioning device for manual scanning constitute the two major challenges of the proposed system. This paper first presents the range sensor and the optical tracking system. The main aspects including the calibration approach and the sensor integration are also described in the following sections. An error analysis has been conducted to predict the expected results. Finally, experimental results are presented to validate the overall system.

Smart laser profiler

In order to meet the needs of many diverse industrial 3D inspection tasks, INO has developed a new concept for the design of a smart and modular 3D laser profiler. This stand-alone sensor which we call Smart Laser Profiler (SLP) is composed of a laser line projector, collection optics, a high frame rate camera and a digital signal processor (DSP). The on-board DSP is the key to this technology. The SLP sensor has been designed to be both compact and rugged and it is enclosed in a water resistant NEMA 4 class housing that is easy to install on a production line. The Smart Laser Profiler has several preprogrammed functions on the DSP that implement basic shape analysis algorithms like volume measurement and shape conformance. For more complex shape analysis, the sensor can transfer the raw 3D profiles to a PC through a high-speed communication link. The present article will describe both the unique hardware, electronics and optical architecture of the sensor and the software tools that were developed.