Increased Productivity for Redundant Laser Scanners Using an Optimal Trajectory Separation Method

2016 ◽  
Vol 10 (6) ◽  
pp. 941-949
Author(s):  
Titus Haas ◽  
◽  
Maximilian Warhanek ◽  
Michael Dietlicher ◽  
Konrad Wegener ◽  
...  

Combining an optical laser scanning system with mechanical axes in a redundant configuration and synchronised control allows the separation of scanning motions according to the strengths of the two systems. Assigning the highly dynamic movement part to the agile optical axes reduces the acceleration and jerk of the mechanical axes. The mechanical axes enable precise motion over the whole workspace, that cannot be achieved by optical systems. The determination of the ideal trajectory separation among the two redundant systems poses an optimisation problem. This study proposes a method for the calculation of the optimal trajectory separation and for productivity increases. Furthermore, a windowing technique is introduced to limit the required computational power. The operation of the optimisation algorithm is demonstrated based on example geometries. It is shown that the machining time is decreased, and the jerk of the solution is minimised. The method is verified using a laser scanning system.

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1436
Author(s):  
Kassahun Demissie Tola ◽  
Dai Quoc Tran ◽  
Byoungjoon Yu ◽  
Seunghee Park

Corrosion detection using a pulsed laser scanning system can be performed via ultrasonic wave propagation imaging. This method outputs illustrations of the wave field within the host structure; thus, it can depict wave–corrosion area interactions. Additionally, post-processing can be performed to enhance the visualization of corroded areas. The wavefield energy computed using RMS (Root Mean Square) is a validated post-processing tool capable of displaying the location and area of corrosion-damaged regions. Nonetheless, to characterize corrosion, it is necessary to determine its depth. The measurement of depth in conjunction with that of the corroded area via the RMS distribution enables the determination of all dimensions of corrosion damage. Thereafter, the flaw severity can be evaluated. This study employed a wavefield within a plate on which corrosion was developed artificially to generate frequency–wavenumber dispersion curves. The curves were compared with their counterparts from a corrosion-free plate. Alternatively, they could be compared with dispersion curves drawn using the depth and material properties of a pristine plate via a computer program. Frequency–wavenumber pairs were extracted from the dispersion curves produced using the portion of the wavefield within the corroded area. These were inserted into the Rayleigh–Lamb equation, from which depths were calculated and averaged.


2015 ◽  
Vol 9 (4) ◽  
Author(s):  
Erik Heinz ◽  
Christian Eling ◽  
Markus Wieland ◽  
Lasse Klingbeil ◽  
Heiner Kuhlmann

AbstractIn recent years, kinematic laser scanning has become increasingly popular because it offers many benefits compared to static laser scanning. The advantages include both saving of time in the georeferencing and a more favorable scanning geometry. Often mobile laser scanning systems are installed on wheeled platforms, which may not reach all parts of the object. Hence, there is an interest in the development of portable systems, which remain operational even in inaccessible areas. The development of such a portable laser scanning system is presented in this paper. It consists of a lightweight direct georeferencing unit for the position and attitude determination and a small low-cost 2D laser scanner. This setup provides advantages over existing portable systems that employ heavy and expensive 3D laser scanners in a profiling mode.A special emphasis is placed on the system calibration, i. e. the determination of the transformation between the coordinate frames of the direct georeferencing unit and the 2D laser scanner. To this end, a calibration field is used, which consists of differently orientated georeferenced planar surfaces, leading to estimates for the lever arms and boresight angles with an accuracy of mm and one-tenth of a degree. Finally, point clouds of the mobile laser scanning system are compared with georeferenced point clouds of a high-precision 3D laser scanner. Accordingly, the accuracy of the system is in the order of cm to dm. This is in good agreement with the expected accuracy, which has been derived from the error propagation of previously estimated variance components.


2018 ◽  
Vol 50 (3) ◽  
pp. 310-322 ◽  
Author(s):  
Xiping Wang ◽  
Ed Thomas ◽  
Feng Xu ◽  
Yunfei Liu ◽  
Brian K Brashaw ◽  
...  

1991 ◽  
Author(s):  
Roswell W. Austin ◽  
Seibert Q. Duntley ◽  
Richard L. Ensminger ◽  
Theodore J. Petzold ◽  
Raymond C. Smith

2011 ◽  
Vol 99 ◽  
pp. S467
Author(s):  
C. Thornberg ◽  
M. Krantz ◽  
F. Nordström ◽  
R. Ljungqvist ◽  
S. Bäck

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