A 200Hz small range image sensor using a multi-spot laser projector

Abstract — In this paper, a high-speed range image sensor using a multi-spot laser projector is constructed. Several high-speed range image sensors have been developed recently. Their sampling rate is around the video rate (30Hz or so) and a faster sensor is required. The proposed sensor has achieved 200Hz measurement. It consists of a commercially available laser projector and a high-speed CCD camera. The number of pixels is 361 and the measurement range is 800-2000mm. Although the acquired range image is sparse, the proposed sensor is thought to be adequate for several applications such as robot vision because of its high-speed imaging and compactness. Some characteristics such as measurement errors are discussed, and the effectiveness of the proposed sensor is verified by experiments. I

Research on performance improvement method of the contact-type sensor

九州工業大学博士学位論文 学位記番号:工博甲第395号 学位授与年月日:平成27年9月25日1 緒論|2 配管内移動ロボットに搭載する回転式センサ位置制御法の開発|3 走査型接触式センサシステムのセンサ部振動抑制制御法|4 EMATによる超音波入射方向可変システムの開発|5 結論九州工業大学平成27年

Position and orientation correction for pipe profiling robots

Sewer pipelines are prevalent, important, valuable, unnoticed, and often in a state of disrepair. Pipeline inspection is essential for effective management of wastewater systems and is now mandated for many municipalities complying with the Governmental Accounting Standards Board Statement 34 and EPA regulations. Pipe inspection robots are routinely used to inspect underground pipelines for cracks, deformations, leaks, blockages and other anomalies to prevent catastrophic failure and to ensure cost effective maintenance and renewal. Most existing pipe inspection robots only collect video footage of pipe condition. Pipe profiling technology has recently been introduced to allow for measurement of the internal coordinate geometry of pipelines. Accurate radial measurements permit the calculation of several important pipe parameters which aid in the determination of pipe condition and prediction of time to failure. Significant research work has been completed in North America, Europe, Asia and Australia aimed at improving the accuracy and automation of the pipe inspection process. However, standard calibration, verification, reporting and analysis practices must be developed for pipe profilers if coordinate profiling data is to be effectively included in the long term management of pipeline assets. The objective of this research is to quantify the measurement error incurred by a pipe profiler\u27s misalignment with the pipe axis, present a new methodology to correct the measurement error, develop a prototype profiler to verify the equations derived herein, and to further the development of pipe profiler technology at the Trenchless Technology Center at Louisiana Tech University. Equations are derived for pipe ovality as a function of the robot\u27s position and orientation with respect to a pipe to demonstrate the magnitude of the error which is introduced by a robot\u27s misalignment with the pipe axis. A new technique is presented to estimate the position and orientation of a profiler using radial measurement devices at each of its ends. This technique is demonstrated by applying homogeneous coordinate transformations to simulated radial measurements based on mathematically generated data that would be obtained by incrementally rotating two parallel radial measuring devices in a perfectly cylindrical pipe. A prototype pipe profiling robot was developed to demonstrate the new position and orientation technique and to experimentally verify the measurement error caused by a robot\u27s misalignment with the pipe axis. This work improves the accuracy and automation of pipe profiling technology and makes a case for the development of industry standard calibration, verification, reporting and analysis practices

Uncertainty and error in laser triangulation measurements for pipe profiling

Underground pipeline infrastructure often receives insufficient attention and maintenance. Those responsible for ensuring the continuing functionality of this infrastructure primarily use subjective information in their decision making, and standards defining the level of damage acceptable before repair or replacement are difficult to implement. Laser pipe profiling is a relatively new technology that has emerged to take a step toward the objective assessment of buried assets. A laser profiler is a device that traverses a section of pipe, taking measurements of radius around the circumference of the inner pipe wall at multiple locations along the length of the pipe. The accuracy of the measurements obtained by a profiler is a critical piece of knowledge for the evaluation of its usefulness. Analytical measurement and uncertainty models were developed for three laser profiling configurations. These configurations involved a digital camera and a laser whose relative position and orientation were fixed relative to one another. The three configurations included (1) a conically projected laser aligned with the pipe axis, (2) a planar laser placed perpendicular to the pipe axis, and (3) a side-facing laser that projected a line onto the pipe wall parallel to the axis of the pipe. The models utilized normalized system parameters to compute pipe geometry from digital images that reveal the intersection of the laser light and the pipe wall; error propagation techniques were applied to compute the variation in measurement uncertainty as a function of position in the measurement space. Analytical evaluation of the conical projection configuration revealed infinite measurement error for a region of the measurement space; the unbounded error was eliminated by utilizing two conical lasers. The accuracy and uncertainty of the perpendicular plane and side facing configurations were much better than for the conical configuration. Physical models of these two configurations were constructed, and measurements were collected for a pipe section to validate the measurement and uncertainty predictions of the analytical models. The difference between observed worst-case laser measurement error and predicted uncertainty was on the order of 0.1% of nominal pipe radius. This work provides pipe profiler designers the analytical detail required to understand the relationship between system geometry, camera parameters and measurement accuracy. The work provides asset managers with a reference against which to evaluate laser profiling for their infrastructure condition monitoring needs