Julio C. Rodríguez-Quiñonez

Surface recognition improvement in 3D medical laser scanner using Levenberg-Marquardt method

The 3D measurements of the human body surface or anatomical areas have gained importance in many medical applications. Three dimensional laser scanning systems can provide these measurements; however usually these scanners have non-linear variations in their measurement, and typically these variations depend on the position of the scanner with respect to the person. In this paper, the Levenberg-Marquardt method is used as a digital rectifier to adjust this non-linear variation and increases the measurement accuracy of our 3D Rotational Body Scanner. A comparative analysis with other methods such as Polak-Ribire and quasi-Newton method, and the overall system functioning is presented. Finally, computational experiments are conducted to verify the performance of the proposed system and its method uncertainty.

Combined application of Power Spectrum Centroid and Support Vector Machines for measurement improvement in Optical Scanning Systems

In this paper Support Vector Machine (SVM) Regression was applied to predict measurements errors for Accuracy Enhancement in Optical Scanning Systems, for position detection in real life application for Structural Health Monitoring (SHM) by a novel method, based on the Power Spectrum Centroid Calculation in determining the energy center of an optoelectronic signal in order to obtain accuracy enhancement in optical scanning system measurements. In the development of an Optical Scanning System based on a 45^o - sloping surface cylindrical mirror and an incoherent light emitting source, surged a novel method in optoelectronic scanning, it has been found that in order to find the position of a light source and to reduce errors in position measurements, the best solution is taking the measurement in the energy centre of the signal generated by the Optical Scanning System. The Energy Signal Centre is found in the Power Spectrum Centroid and the SVM Regression Method is used as a digital rectified to increase measurement accuracy for Optical Scanning System.

Mobile robot vision system using continuous laser scanning for industrial application

Purpose The purpose of this paper is the presentation and research of a novel robot vision system, which uses laser dynamic triangulation, to determine three-dimensional (3D) coordinates of an observed object. The previously used physical operation principle of discontinuous scanning method is substituted by continuous method. Thereby applications become possible that were previously limited by this discretization. Design/methodology/approach The previously used prototype No. 2, which uses stepping motors to realize a discontinuous laser scan, was substituted by the new developed prototype No. 3, which contains servomotors, to achieve a continuous laser scan. The new prototype possesses only half the width and turns out to be significantly smaller and therefore lighter than the old one. Furthermore, no transmissions are used, which reduce the systematic error of laser positioning and increase the system reliability. Findings By using a continuous laser scan method instead of discontinuous laser scan method, dead zones in the laser scanner field can be eliminated. Thereby, also by changing the physical operation principle, the implementation of applications is allowed, which previously was limited by the fixed step size or by the object distance under observation. By using servomotors instead of stepping motors, also a significant reduced positioning time can be accomplished maintaining the relative positioning error less than 1 per cent. Originality/value The originality is based on the substitution of the physical operation principle of discontinuous by continuous laser scan. The previously used stepping motors discretized the laser scanner field and thereby produced dead zones, where 3D coordinates cannot be detected. These stepping motors were substituted by servomotors to revoke these disadvantages and provide a continuous laser scan, where dead zones in the field of view get eliminated and the step response of the laser scanner accelerated.

Energy Center Detection in Light Scanning Sensors for Structural Health Monitoring Accuracy Enhancement

This paper introduces a novel electronic circuit that has to be embedded in a photodiode sensor as an integrated circuit board for electronic signal processing that detects the energy center of an optical signal, which represents the most accurate position measurement from a light emitter source mounted on a structure (such as a building, a bridge, or a mine). The optical scanning sensor for structural health monitoring proposed is a flexible system that can operate with a coherent or incoherent light emitter source. It is conformable to any kind of structure surfaces and data storage budget thanks to the signal processing stage being embedded into the sensor and does not require additional software processing, which reduces the time and memory spacing requirements for information recording. The theoretical principle of operation, as well as the technological and experimental aspects of design, development, and validation is presented.

Scanning for light detection and Energy Centre Localization Methods assesment in vision systems for SHM

In this research, six Energy Centre Localization Methods are assessed by Wilcoxon Signed Rank Test. Due to SHM is an upcoming tendency of determining the integrity of structures and development of strategies to prevent undesirable damage, it is necessary to detect a light emitter mounted on the structure under monitoring and calculate the energy centre localization. After a short introduction to the energy centre localization methods, a machine learning technique was applied to predict measurement errors and adjust non-linear variation for measurement accuracy improvement. An Optical Scanning System was enhanced by measurement at the optical signal energy centre and error adjustment by SVM algorithm. The theoretical methods principles, experimental development and validation are presented.

Continuous 3D scanning mode using servomotors instead of stepping motors in dynamic laser triangulation

A novel principle of dynamic triangulation with a laser scanner was developed at the institute of engineering UABC. This coordinate measurement method uses stepping motors for positioning a laser in a defined field of view. The present paper describes the substitution of these stepping motors with robust controlled servomotors in open- and closed-loop configuration. This approach converts the discontinuous (i.e. discrete steps) scanning method into a continuous one, to eliminate dead zones in the field of view and to accelerate the step response of the laser scanner.

Optimal kinematic control of a robotic excavator with laser TVS feedback

The problem of optimal kinematic control of an excavator manipulator motion for a given trajectory is considered. The minimizing of the quadratic functional of the angles associated with the respective weights as the optimality criterion is adopted. The efficiency of proposed method is confirmed by numerical example. Offered laser Technical Vision System (TVS) completes the designed controller with necessary tool for effective feedback about manipulator coincidence with desired trajectory.

Improve 3D laser scanner measurements accuracy using a FFBP neural network with Widrow-Hoff weight/bias learning function

Many laser scanners depend on their mechanical construction to guarantee their measurements accuracy, however, the current computational technologies allow us to improve these measurements by mathematical methods implemented in neural networks. In this article we are going to introduce the current laser scanner technologies, give a description of our 3D laser scanner and adjust their measurement error by a previously trained feed forward back propagation (FFBP) neural network with a Widrow-Hoff weight/bias learning function. A comparative analysis with other learning functions such as the Kohonen algorithm and gradient descendent with momentum algorithm is presented. Finally, computational simulations are conducted to verify the performance and method uncertainty in the proposed system.

3D Body & Medical Scanners’ Technologies: Methodology and Spatial Discriminations

Medical practitioners have traditionally measured the body’s size and shape by hand to assess health status and guide treatment. Now, 3D body-surface scanners are transforming the ability to accurately measure a person’s body size, shape, and skin-surface area (Treleaven & Wells, 2007) (Boehnen & Flynn, 2005). In recent years, technological advances have enabled diagnostic studies to expose more detailed information about the body’s internal constitution. MRI, CT, ultrasound and X-rays have revolutionized the capability to study physiology and anatomy in vivo and to assist in the diagnosis and monitoring of a multitude of disease states. External measurements of the body are more than necessary. Medical professionals commonly use size and shape to production of prostheses, assess nutritional condition, developmental normality, to analyze the requirements of drug, radiotherapy, and chemotherapy dosages. With the capability to visualize significant structures in great detail, 3D image methods are a valuable resource for the analysis and surgical treatment of many pathologies.

Optical Cyber-Physical System Embedded on an FPGA for 3D Measurement in Structural Health Monitoring Tasks

Abstract This paper presents the description of a cyber-physical system embedded on an FPGA for 3D measurement in structural health monitoring tasks. The implementation technique and performance evaluation demonstrate the contribution of this paper to the mathematical fundamentals adaptation of an on-site rotatory scanning system to a cyber-physical system. In particular, it is described in detail the design of a virtual angle measurement soft sensing technique based on the information conversion of an optoelectronic signal provided by a rotatory scanning system through an FPGA. Behaving the FPGA as the sensor controller and the actuator in the scanning system. Using the measurement of angles through the proposed embedded system, it can be calculated the coordinates and displacement of specific indicators distributed over a structure under observation. Providing online data exchange from on-site measurement to a remote computational station for real-time or posteriorly data analysis.