Limits...
A Cross Structured Light Sensor and Stripe Segmentation Method for Visual Tracking of a Wall Climbing Robot.

Zhang L, Sun J, Yin G, Zhao J, Han Q - Sensors (Basel) (2015)

Bottom Line: An adaptive monochromatic space is applied to preprocess the image with ambient noises.In the monochromatic image, the laser stripe obtained is recovered as a multichannel signal by minimum entropy deconvolution.Lastly, the stripe centre points are extracted from the image.

View Article: PubMed Central - PubMed

Affiliation: College of Computer Science and Technology, Harbin Engineering University, Harbin 150001, China. zhangliguo@hrbeu.edu.cn.

ABSTRACT
In non-destructive testing (NDT) of metal welds, weld line tracking is usually performed outdoors, where the structured light sources are always disturbed by various noises, such as sunlight, shadows, and reflections from the weld line surface. In this paper, we design a cross structured light (CSL) to detect the weld line and propose a robust laser stripe segmentation algorithm to overcome the noises in structured light images. An adaptive monochromatic space is applied to preprocess the image with ambient noises. In the monochromatic image, the laser stripe obtained is recovered as a multichannel signal by minimum entropy deconvolution. Lastly, the stripe centre points are extracted from the image. In experiments, the CSL sensor and the proposed algorithm are applied to guide a wall climbing robot inspecting the weld line of a wind power tower. The experimental results show that the CSL sensor can capture the 3D information of the welds with high accuracy, and the proposed algorithm contributes to the weld line inspection and the robot navigation.

No MeSH data available.


Related in: MedlinePlus

Illustration of the weld line inspection system composed of a wall climbing robot, an NDT device and a CSL sensor. (a) The system; (b) Detecting a straight weld line; and (c) T-intersection of weld lines.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4507594&req=5

sensors-15-13725-f001: Illustration of the weld line inspection system composed of a wall climbing robot, an NDT device and a CSL sensor. (a) The system; (b) Detecting a straight weld line; and (c) T-intersection of weld lines.

Mentions: The quality inspection system of the weld line is shown in Figure 1a. It is composed of a wall climbing robot, an ultrasonic NDT device and a CSL sensor. Figure 1b,c illustrate the laser projector and image capturing CCD on a straight weld line and cross weld lines, respectively. Two cross laser planes are projected from the laser projector, forming a convex light stripe around the weld line of the welding surface. The laser projector is fixed on the robot and perpendicular to the welding. Two stripes s1 and s2 are formed by the intersection lines between the weld and two orthogonal laser planes L1 and L2. According to the triangulation measurement method, the 3D information of the weld surface can be calculated by transforming the points of the stripes from the image coordinate system to the global coordinate system.


A Cross Structured Light Sensor and Stripe Segmentation Method for Visual Tracking of a Wall Climbing Robot.

Zhang L, Sun J, Yin G, Zhao J, Han Q - Sensors (Basel) (2015)

Illustration of the weld line inspection system composed of a wall climbing robot, an NDT device and a CSL sensor. (a) The system; (b) Detecting a straight weld line; and (c) T-intersection of weld lines.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4507594&req=5

sensors-15-13725-f001: Illustration of the weld line inspection system composed of a wall climbing robot, an NDT device and a CSL sensor. (a) The system; (b) Detecting a straight weld line; and (c) T-intersection of weld lines.
Mentions: The quality inspection system of the weld line is shown in Figure 1a. It is composed of a wall climbing robot, an ultrasonic NDT device and a CSL sensor. Figure 1b,c illustrate the laser projector and image capturing CCD on a straight weld line and cross weld lines, respectively. Two cross laser planes are projected from the laser projector, forming a convex light stripe around the weld line of the welding surface. The laser projector is fixed on the robot and perpendicular to the welding. Two stripes s1 and s2 are formed by the intersection lines between the weld and two orthogonal laser planes L1 and L2. According to the triangulation measurement method, the 3D information of the weld surface can be calculated by transforming the points of the stripes from the image coordinate system to the global coordinate system.

Bottom Line: An adaptive monochromatic space is applied to preprocess the image with ambient noises.In the monochromatic image, the laser stripe obtained is recovered as a multichannel signal by minimum entropy deconvolution.Lastly, the stripe centre points are extracted from the image.

View Article: PubMed Central - PubMed

Affiliation: College of Computer Science and Technology, Harbin Engineering University, Harbin 150001, China. zhangliguo@hrbeu.edu.cn.

ABSTRACT
In non-destructive testing (NDT) of metal welds, weld line tracking is usually performed outdoors, where the structured light sources are always disturbed by various noises, such as sunlight, shadows, and reflections from the weld line surface. In this paper, we design a cross structured light (CSL) to detect the weld line and propose a robust laser stripe segmentation algorithm to overcome the noises in structured light images. An adaptive monochromatic space is applied to preprocess the image with ambient noises. In the monochromatic image, the laser stripe obtained is recovered as a multichannel signal by minimum entropy deconvolution. Lastly, the stripe centre points are extracted from the image. In experiments, the CSL sensor and the proposed algorithm are applied to guide a wall climbing robot inspecting the weld line of a wind power tower. The experimental results show that the CSL sensor can capture the 3D information of the welds with high accuracy, and the proposed algorithm contributes to the weld line inspection and the robot navigation.

No MeSH data available.


Related in: MedlinePlus