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Article

Cengiz Deniz and Mustafa Cakir

This paper aims to introduce a simple hand-eye calibration method that can be easily applied with different objective functions.

Abstract

Purpose

This paper aims to introduce a simple hand-eye calibration method that can be easily applied with different objective functions.

Design/methodology/approach

The hand-eye calibration is solved by using the closed form absolute orientation equations. Instead of processing all samples together, the proposed method goes through all minimal solution sets. Final result is chosen after evaluating the solution set for arbitrary objectives. In this stage, outliers can be excluded optionally if more accuracy is desired.

Findings

The proposed method is very flexible and gives more accurate and convenient results than the existing solutions. The mathematical error expression defined by the calibration equations may not be valid in practice, where especially systematic distortions are present. It is shown in the simulations that the solution which results the least mathematical error in systems may have incorrect, incompatible results in the presence of practical demands.

Research limitations/implications

The performance of the calibration performed with the proposed method is compared with the reference methods in the literature. When the back-projection error is benchmarked, which corresponds to the point repeatability, the proposed approach is considered as the most successful method among all others. Due to its robustness, it is decided to make tooling-sensor calibrations by the recommended method, in the robotic non-destructive testing station in Ford-OTOSAN Kocaeli Plant Body Shop Department.

Originality/value

Arranging the well-known AX = XB calibration equation in quaternion representation as Q_A = Q_x × Q_B × Q_x reveals another common spatial rotation equation. In this way, absolute orientation solution satisfies the hand-eye calibration equations. The proposed solution is not presented in the literature as a standalone hand-eye calibration method, although some researchers drop a hint to the relative formulations.

Details

Industrial Robot: An International Journal, vol. 45 no. 1
Type: Research Article
ISSN: 0143-991X

Keywords

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Article

Cengiz Deniz and Mustafa Cakir

The purpose of this study is to design a robotic inline measurement system for spot welding quality control to achieve process requirement without any operator during the…

Abstract

Purpose

The purpose of this study is to design a robotic inline measurement system for spot welding quality control to achieve process requirement without any operator during the manufacturing flow.

Design/methodology/approach

A robot manipulator carries a stereo-camera and an ultrasonic control probe. The center position of the spot welding point is determined by evaluating the results of the edge, gradient and symmetry approaches from the methods proposed up to now in the literature to increase reliability. The center position of the spot welding point, determined in the camera reference plane, is transferred to the robot base plane coordinates with the hand–eye calibration proposed in this manuscript. Weld quality is checked by the ultrasonic test probe located at the spot welding point.

Findings

While operators can only control welding quality, the developed station can also evaluate the quality based on geometric accuracy by processing the deviation of the position of the spot welding points. The proposed calibration method and the results of other methods in the literature are presented in this study by comparing it with synthetic data in simulations and in practical application.

Research limitations/implications

The quality control is performed not only for the spot welding made with robots but also for the manual welds as well. Because of vision configuration, and reliability issues, maximum allowable offset by the correct spot position is limited to 20 mm to position the manipulator for testing. The installation and pretest works of the developed robotic welding quality control station are completed in the Body Shop Area of Ford Otosan factory in Kocaeli/Turkey. The results of the robotic control process are monitored by the quality assurance team. Integration of automation with the production line will be completed and an inline measurement will be done.

Originality value

In this paper, a new hand–eye calibration method based on simple and closed-form analytical solutions has been presented. The objective function is defined as reducing the deviation in the point projection, rather than reducing the error in the calibration equation. To increase reliability, combining the results of existing centering algorithms for the detection of the strongly deformed spot welding spot center, although it is normally in a circular form, has been suggested.

Details

Industrial Robot: An International Journal, vol. 45 no. 1
Type: Research Article
ISSN: 0143-991X

Keywords

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Article

Mustafa Cakir and Cengiz Deniz

The purpose of this study is to present a novel method for industrial robot TCP (tool center point) calibration. The proposed method offers fully automated robot TCP…

Abstract

Purpose

The purpose of this study is to present a novel method for industrial robot TCP (tool center point) calibration. The proposed method offers fully automated robot TCP calibration within a defined cycle time. The method is applicable for large-scale installations due to its zero cost for each robot.

Design/methodology/approach

Precise and expensive measuring equipment or specially designed reference devices are required for robot calibration. The calibration can be performed by using only one plane plate in this method, and the calibration procedure is defined step by step: the robot moves to the target plane position. Then, the TCP touches the plane and the actual robot configuration is recorded. Then robot moves back into position and the same step is repeated for a new sample. Alternatively, the robot can be stationary and the plane can be moved towards the robot TCP. TCP is calculated by processing the difference of the contact points recorded at different positions. The process is fully automated. No special equipment is used. The calculations are very simple, and the robot controller can easily be realized.

Findings

The conventional manual robot TCP calibration process takes about 15 min and takes more time in case of the high accuracy. The proposed method reduces this time to less than 3 min without operator support. Practical tests have shown that TCP calibration can be performed with 0.1-0.6 mm of accuracy. This solution is an automated process and does not require special installation and it also has approximately zero cost. For this reason, this study recommends using the proposed solution widely in areas where even one or hundreds of robots are located.

Research limitations/implications

In this study, the data were directly taken from the robot controller without using any special measuring equipment. The industrial robot used in the tests has no absolute calibration. The classical “four-point method” was used for reference TCP data. It is the initial acceptance that this process conducted with extreme care and by using a needle-tipped tool will not produce exact values. It was observed that deviation of the TCP from a fixed point in reorient motions was not more than 0.5 mm. This method has been validated for different bits. The pilot works for different robot applications in Ford Otosan Gölcük Plant have been completed and dissemination has started.

Originality/value

Although the approach uses is clear and simple, it is surprising that the calculation of TCP using plane equations has so far not been mentioned in the literature. The disadvantage of using either fixed point or sphere as a reference is that the TCP cannot automatically guide to the target. This problem was overcome with the use of a larger target plane plate and the process was fully automated. The proposed method can be widely used in practical applications.

Details

Industrial Robot: the international journal of robotics research and application, vol. 46 no. 5
Type: Research Article
ISSN: 0143-991X

Keywords

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Article

Deniz Sarica, Vecdi Demircan, Aybike Erturk and Nilay Arslantas

The purpose of the research is to identify the various factors affecting bread wastage and bread consumption of consumers in Isparta, Turkey.

Abstract

Purpose

The purpose of the research is to identify the various factors affecting bread wastage and bread consumption of consumers in Isparta, Turkey.

Design/methodology/approach

This study uses the categorical regression (CATREG) model to estimate the driving forces of bread waste and consumption. The study concentrates on data obtained from 384 respondents speaking for the same number of households placed in the province of Isparta in Turkey.

Findings

The results indicate that both models are statistically significant at the 1% level. Parents' profession, storage method, type of bread consumed, daily bread expenditure, monthly income and the idea of “bread is cheap” are the most important variables affecting bread wastage. Regarding bread consumption, parents' profession, fathers' education level, monthly income, inadequate control in bakeries, household size and the idea of “bread makes people fat” are found to play significant roles.

Practical implications

The results could be helpful to develop influential policies on healthy eating and aiming plans to reduce bread consumption to healthy levels and prevent bread waste.

Social implications

This research contributes to knowledge regarding the underlying causes of the bread consumption and wastage of Turkish consumers in the light of the data analysis for Isparta province.

Originality/value

This paper contains unique and original understandings concerning bread consumption and wastage attitudes and determinants for consumers from Isparta, Turkey. The novel findings of this research have conduced to a better understanding of the key factors that affect bread consumption and waste. The paper also applies an econometric analysis using a CATREG model to analyse the factors influencing consumers' bread waste and consumption behaviour in Isparta province, Turkey.

Details

British Food Journal, vol. 123 no. 4
Type: Research Article
ISSN: 0007-070X

Keywords

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Article

Mahmut Kayar, Suleyman Ilker Mistik and Deniz Inan

– The purpose of this paper is to investigate the factors effecting ultrasonic seam tensile properties.

Abstract

Purpose

The purpose of this paper is to investigate the factors effecting ultrasonic seam tensile properties.

Design/methodology/approach

In this study, 100 percent polypropylene and 100 percent polyester spunbond and meltblown nonwoven fabrics were sewn by using ultrasonic sewing machine with different rollers which have two, three and four rows. Seam tensile properties of the sewn nonwoven fabrics were investigated. Four-Level Nested Anova Design was applied to the data by using Minitab 15 software program.

Findings

Higher seam strength values were obtained by using four rows roller, PP fiber, spunbond fabric and 50 g/m2 fabric area density for all nonwoven fabrics. Statistical significance was found between fabric area density, roller rows and seam tensile strength properties and between fabric type, roller rows and seam elongation at break values.

Originality/value

When the authors look at the studies related to ultrasonic sewing, several researchers studied on welding parameters of ultrasonic sewing but very limited studies were performed on assembling of nonwoven fabrics with ultrasonic sewing. Therefore effect of production methods of nonwoven fabrics on the properties of ultrasonic sewing such as seam strength and elongation at break should be investigated.

Details

International Journal of Clothing Science and Technology, vol. 27 no. 6
Type: Research Article
ISSN: 0955-6222

Keywords

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Abstract

Details

Marketing Management in Turkey
Type: Book
ISBN: 978-1-78714-558-0

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Article

Burak Keskin and Can Deniz Köksal

The purpose of this paper is to employ an efficiency analysis and compare the efficiency scores of publicly or privately operated airports in Turkey.

Abstract

Purpose

The purpose of this paper is to employ an efficiency analysis and compare the efficiency scores of publicly or privately operated airports in Turkey.

Design/methodology/approach

This study uses analytic hierarchy process, which is one of the widely known multi-criteria decision-making methods to calculate the relative weights of input and outputs. This study also uses data envelopment analysis and assurance region (AR) method to calculate the efficiency scores of airports at the empirical analysis stage.

Findings

The empirical results reveal that DEA-BCC and DEA-CCR methods produced almost the same efficiency scores, and 14 airports were found as efficient. Also, AR method was employed and under this method, it was only two airports operated by the private sector that were found as efficient. None of the publicly operated airports was found as efficient.

Practical implications

The main practical implication of this study is that publicly operated airports must improve their efficiency levels in Turkey. This situation indicates that the government policy for the aviation sector must be changed. It is not a coincidence that all publicly operated airports are inefficient. To cope with this situation, it may be a useful policy that establishes a regional airport system or applies the privatization process to all airports.

Originality/value

The most significant contribution of this study to literature is that the AR method, which was never used before in a single country’s airport performance evaluation study, was applied for the first time. Also, this technique was applied first time to Turkish airports for measuring their efficiency levels.

Details

International Journal of Productivity and Performance Management, vol. 68 no. 3
Type: Research Article
ISSN: 1741-0401

Keywords

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Article

Ewan Sutherland

– The purpose of this paper is to examine the nature and extent of corruption in the telecommunications sector in Azerbaijan and the associated issues of governance.

Abstract

Purpose

The purpose of this paper is to examine the nature and extent of corruption in the telecommunications sector in Azerbaijan and the associated issues of governance.

Design/methodology/approach

A case study examining a wide range of sources on Azerbaijan.

Findings

Unusually, perhaps uniquely, ownership of major operators has been concealed. Nonetheless, the presidential family controls one of three mobile operators and has a stake in a second.

Research limitations/implications

A law from 2012 conceals the beneficial ownership of some operators, others merely use offshore registries.

Originality/value

One of only half a dozen case studies on corruption in telecommunications. It is very unusual in the extent to which ownership of operators is hidden.

Details

info, vol. 17 no. 5
Type: Research Article
ISSN: 1463-6697

Keywords

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