Development of a Robust and Accurate Positioning System in Micromachining Based on CAMERA and LCD Screen

Ortiz, Óscar de Francisco; Sánchez-Reinoso, H.T.; Estrems-Amestoy, M.

doi:10.1016/j.proeng.2015.12.575

Cited by 5 publications

(6 citation statements)

References 4 publications

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“…Because of this, in this work, three different methods have been presented to achieve an absolute positioning system based on a vision system in which an asymmetric pattern in the form of a logarithmic spiral has been used. This pattern is different from the one used for the development of the camera-screen system presented in previous works [8] based on a pattern of illuminated repetitive LEDs on the screen in which the position calculation was always based on the relative position with respect to the previous point calculated. Such a method, in case of mechanical errors in the system, could provide multiple position solutions, causing the loss of reference.…”

Section: Discussionmentioning

confidence: 99%

“…In the context of micromachining, Chen et al [4] proposed a machine method to measure and compensate for errors caused by the inaccuracy of mechanical systems. Furthermore, different closed loop positioning systems that analyze the patterns shown in the image of the LCD screen have been developed, achieving a certain degree of accuracy using different approaches such as in Wong [5], Montes [6], Leviton [7] and more recently by de Francisco [8,9].…”

Section: Introductionmentioning

confidence: 99%

“…The algorithm used for the analysis was initially created using Matlab [8]. Theodoridis [17] describes how to perform pattern recognition using Matlab.…”

Section: Introductionmentioning

confidence: 99%

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New Global Referencing Approach in a Camera-LCD Micro Positioning System

Ortiz¹,

Ortiz²,

Bueno

2020

Sensors

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In any precision manufacturing process, positioning systems play a very important role in achieving a quality product. As a new approach to current systems, camera-LCD positioning systems are a new technology that can provide substantial improvements enabling better accuracy and repeatability. However, in order to provide stability to the system a global positioning system is required. This paper presents an improvement of a positioning system based on the treatment of images on an LCD in which a new algorithm with absolute reference has been implemented. The method is based on basic geometry and linear algebra applied to computer vision. The algorithm determines the spiral center using an image taken at any point. Consequently, the system constantly knows its position and does not lose its reference. Several modifications of the algorithm are proposed and compared. The simulation and test of the algorithm provide an important improvement in the reliability and stability of the positioning system providing errors of microns for the calculation of the global position used by the algorithm.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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New Global Referencing Approach in a Camera-LCD Micro Positioning System

Ortiz¹,

Ortiz²,

Bueno

2020

Sensors

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“…Thanks to the advances in screen and camera technology, positioning algorithms that analyze a pattern shown in a photographic image have been developed [1,2]. More recently, camera-screen positioning systems with dedicated artificial vision algorithms [3][4][5] have provided high precision at a very interesting cost compared to other positioning technologies such as encoders or resolvers.…”

Section: Introductionmentioning

confidence: 99%

“…Consequently, this article presents an enhanced method of recalculating the center of the image used by the positioning algorithm in an LCD-camera system, similar to that developed by de Francisco [4] and improved in subsequent studies [42], but being completely different from such previous studies regarding the procedure to calculate the positioning of the part with respect to the reference system of the screen. In previous works, the positioning was obtained through the global center of gravity of the 25 selected LEDs in the image.…”

Section: Introductionmentioning

confidence: 99%

Enhanced Positioning Algorithm Using a Single Image in an LCD-Camera System by Mesh Elements’ Recalculation and Angle Error Orientation

Ortiz¹,

Amestoy

Reinoso

et al. 2019

Materials

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In this article, we present a method to position the tool in a micromachine system based on a camera-LCD screen positioning system that also provides information about angular deviations of the tool axis during its running. Both position and angular deviations are obtained by reducing a matrix of LEDs in the image to a single rectangle in the conical perspective that is treated by a photogrammetry method. This method computes the coordinates and orientation of the camera with respect to the fixed screen coordinate system. The used image consists of 5 × 5 lit LEDs, which are analyzed by the algorithm to determine a rectangle with known dimensions. The coordinates of the vertices of the rectangle in space are obtained by an inverse perspective computation from the image. The method presents a good approximation of the central point of the rectangle and provides the inclination of the workpiece with respect to the LCD screen reference system of coordinates. A test of the method is designed with the assistance of a Coordinate Measurement Machine (CMM) to check the accuracy of the positioning method. The performed test delivers a good accuracy in the position measurement of the designed method. A high dispersion in the angular deviation is detected, although the orientation of the inclination is appropriate in almost every case. This is due to the small values of the angles that makes the trigonometric function approximations very erratic. This method is a good starting point for the compensation of angular deviation in vision based micromachine tools, which is the principal source of errors in these operations and represents the main volume in the cost of machine elements’ parts.

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