Luis C. Basaca-Preciado

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.

Electromechanical 3D Optoelectronic Scanners: Resolution Constraints and Possible Ways of Improvement

Non-Contact optoelectronic 3D measurement is a rapidly growing field. Three-Dimensional Non-Contact Measurement Technologies are very common for research due to multiple practical applications expecting for its benefits. Many fields are using in any way 3D measurements or shape recognition, some of them there are vision assisted assembly in various branches of industry, autonomous mobile robots navigation, structural health monitoring, micro surfaces inspections, precise automated surgery, etc. In this chapter it is expedient to mention and briefly cross-compare the following emerging technologies for 3D measurements: laser scanners, lasers based on conoscopy holography technology and 3D cameras. Laser scanners: Most contemporary non-contact 3D measurement devices are based on laser range scanning. The simplest devices (Fischer, 2007) are based on the laser triangulation technique. This is an active stereoscopic technique in which the distance of the object is computed by means of a directional light source and a video camera. The CCD camera’s 2D array captures the image of surface profile and digitizes all data points along the laser disadvantage of this method is that a single camera collects only a small percentage of the reflected energy. The amount of the collected energy can be drastically increased by trapping the entire reflection cone, thus significantly increasing the precision and reliability of the measurements. Lasers based on Conoscopic Holography technology: Conoscopic Holography is a simple implementation of a particular type of polarized light interference process based on crystal optics. In the basic interference set-up, a point of light is projected onto a diffuse object. This point creates a light point, which diffuses light in every direction. In a conoscopic system, a complete solid angle of the diffused light is analyzed by the system. The measurement

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.

Exact laser beam positioning for measurement of vegetation vitality

Purpose The purpose of this paper is to present a novel application for a newly developed Technical Vision System (TVS), which uses a laser scanner and dynamic triangulation, to determine the vitality of agriculture vegetation. This vision system, installed on an unmanned aerial vehicle, shall measure the reflected laser energy and thereby determine the normalized differenced vegetation index. Design/methodology/approach The newly developed TVS shall be installed on the front part of the unmanned aerial vehicle, to perform line-by-line scan in the vision system field-of-view. The TVS uses high-quality DC motors, instead of previously researched low-quality DC motors, to eliminate the existence of two mutually exclusive conditions, for exact positioning of a DC motor shaft. The use of high-quality DC motors reduces the positioning error after control. Findings Present paper emphasizes the exact laser beam positioning in the field-of-view of a TVS. By use of high-quality instead of low-quality DC motors, a significant reduced positioning time was achieved, maintaining the relative angular position error less than 1 per cent. Best results were achieved, by realizing a quasi-continuous control, using a high pulse-width modulated duty cycle resolution and a high execution frequency of the positioning algorithm. Originality/value The originality of present paper is represented by the novel application of the newly developed TVS in the field of agriculture. The vitality of vegetation shall be determined by measuring the reflected laser energy of a scanned agriculture zone. The paper’s main focus is on the exact laser beam positioning within the TVS field-of-view, using high-quality DC motors in closed-loop position control configuration.

Accuracy improvement in 3D laser scanner based on dynamic triangulation for autonomous navigation system

Autonomous navigation has been an important task in recent years to keep track of vehicles location, to provide safety and accuracy on its trajectory and to see their surroundings and predict if it is possible to travel across them. In this paper, a method to improve accuracy on laser vision systems based on dynamic triangulation for mobile robots is proposed. This laser vision system consists on a positioning laser, a scanning aperture and a fixed distance between them. The positioning laser points a laser beam over a surface and it is detected by the scanning aperture. The proposed method to improve accuracy on laser vision systems relies on the scanning aperture; current designs calculate the detection angle counting the pulses of a pulse train across a motor rotation. The disadvantage of this method is that the angular velocity of the motor may vary, resulting in an incorrect calculation of the angle of detection. In the proposed method, a new signal provided by an encoder is used to reduce the error generated by variations in angular velocity.

Photodiode and charge-coupled device fusioned sensors

Machine vision methods to provide spatial coordinates measurement has developed in a wide range of technologies for multiples fields of applications such as robot navigation, medical scanning, and structural monitoring. Each technology with specified properties that could be categorized as advantage and disadvantage according its utility to the application purpose. This paper presents the photodiode and charge coupled device sensors fusion as the base for those systems with non-lineal behavior supported by artificial intelligence techniques, which require the use of information from various sensors for pattern recognition to produce an enhanced output.

Improve laser detection in CCD for integrated photogrammetry - Laser scanner

The specified properties of both the close-range photogrammetry and laser-scanning have their advantages and specific limitations. In this paper we are going to expose such advantage and combine this methods to exploit their natural synergy, additionally a new pre-processing technique to realize a quick identification of the laser centroid and edges detected by a CCD is presented, this technique can be used in a combination with edge detection techniques as Canny and Prewitt methods to obtain more defined edges in an image. Finally the experimentation is presented to see the stability of the identified centroid in the laser reflection at different thresholds using the proposed technique in an Integrated Photogrammetry-Laser Scanner.

Accuracy improvement of vision system for mobile robot navigation by finding the energetic center of laser signal

The presented paper is a follow up work and improvement of a previously published research of a 3D Vision System for mobile robot navigation application. Sensor fusion and redundancy are integrated to the system in order to increase the overall robustness as well as the accuracy of the system measurements by finding the energetic center of the laser signal used by the vision system. New experimental results are presented to demonstrate the increase of system accuracy.

Home and building automation through social networks

People are using social networks for every aspect of their lives, and what this project does is to take advantage of it to develop a scalable platform in which the user could monitor their home, interacting with a virtual assistant running on a server listening to all events fired by the user. Therefore this paper propose a different use of social networks, to manage your home or building through them. The entire platform has been tested with multiple users, scenarios, and also it has been migrated to various frameworks and programming languages to ensure portability.