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Article
Publication date: 4 August 2021

Chenglong Yu, Zhiqi Li, Dapeng Yang, Hong Liu and Alan F. Lynch

This study aims to propose a novel method based on model learning with sparsity inducing norms for estimating dynamic gravity terms of the serial manipulators. This method…

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Abstract

Purpose

This study aims to propose a novel method based on model learning with sparsity inducing norms for estimating dynamic gravity terms of the serial manipulators. This method is realized by operating the robot, acquiring data and filtering the features in signal acquisition to adapt to the dynamic gravity parameters.

Design/methodology/approach

The core principle of the method is to analyze the dictionary composition of the basis function of the model based on the dynamic equation and the Jacobian matrix of an arm. According to the structure of the basis function and the sparsity of the features, combined with joint-angle and driving-torque data acquisition, the effective features of dynamic gravity parameters are screened out using L1-norm optimization and learning algorithms.

Findings

The theoretical analysis revealed that training data obtained based on joint angles and driving torques could rapidly update dynamic gravity parameters. The simulation experiment was carried out by using the publicly available robot model and compared with the previous disassembly method to evaluate the feasibility and performance. The real 7-degree of freedom (DOF) industrial manipulator was used to further discuss the effects of the feature selection. The results show that this estimation method can be fully operational and efficient in industrial applications.

Research limitations/implications

This approach is applicable to most serial robots with multi-DOF and the dynamic gravity parameters of the robot are estimated through learning and optimization. The method does not require prior knowledge of the robot arm structure and only requires joint-angle and driving-torque data acquisition under low-speed motion. Furthermore, as it is a data-driven-based method, it can be applied to gravity parameters updating.

Originality/value

Different from previous general robot dynamic modelling methods, the sparsity of the analytical form of dynamic equations was exploited and model learning was formulated as a convex optimization problem to achieve effective gravity parameters screening. The novelty of this estimation approach is that the method does not only require any prior knowledge but also does not require a specifically designed trajectory. Thus, this method can avoid the laborious work of parameter calibration and the induced modelling errors. By using a data-driven learning approach, the new parameter updating process can be completed conveniently when the robot carries additional mass or the end-effector changes for different tasks.

Details

Industrial Robot: the international journal of robotics research and application, vol. 48 no. 6
Type: Research Article
ISSN: 0143-991X

Keywords

Article
Publication date: 1 April 2014

Bassem Kahouli and Samir Maktouf

– This paper aims to use the approach based on the application of the law of gravity for the study of the flows of export and the effects of the RTAs.

Abstract

Purpose

This paper aims to use the approach based on the application of the law of gravity for the study of the flows of export and the effects of the RTAs.

Design/methodology/approach

In this paper, the authors evaluate the effects of RTAs on exports between members and non-members taking into account the Vinerian specification. The authors also try to estimate the impact of the recent economic crisis on the flows of export and the success of the RTAs. The authors use a model of static and dynamic gravity for 40 countries and six RTAs during the period 1980-2011.

Findings

Definitely the proliferation of RTAs will continue to be one of the driving forces that will constitute the political system and the global economy in the following years. It indicates a process that implies the merger of economies separated in bigger regions of free trade. Regional integration is seen as beneficial in many senses and is the major economic objectives in addition to presenting a stabilizing factor in international relations.

Originality/value

The gravity model is estimated using the last techniques of panel data which takes into account the endogeneity of the effects of integration and the existence of dynamic effect.

Details

International Journal of Development Issues, vol. 13 no. 1
Type: Research Article
ISSN: 1446-8956

Keywords

Article
Publication date: 1 February 1977

JOHN VANDERKAMP

Economists have had problems interpreting the gravity model, particularly as applied to migration behaviour. Its physical analogy is unappealing and theories of economic…

Abstract

Economists have had problems interpreting the gravity model, particularly as applied to migration behaviour. Its physical analogy is unappealing and theories of economic behaviour do not generally give rise to gravity laws. Some years ago Niedercorn and Bechdolt (1969) published a paper in which they provide a derivation of the gravity model using utility theory. Their approach is, however, much more applicable to other flows of human interaction across space, such as travel or communication flows, than it is to migration flows. The major purpose of this paper is to indicate a set of assumptions which might underlie a gravity model of migration and to show that these assumptions are quite severe. One important implication is that we should fully expect any real world migration pattern to deviate from the predictions of a gravity model. Nevertheless, the gravity specification may be a useful starting point in the analysis of migration behaviour, as it imposes restrictions on the formulation of the estimating equations. Thus we may fruitfully study how and why the real world migration patterns diverge from gravity flows.

Details

Journal of Economic Studies, vol. 4 no. 2
Type: Research Article
ISSN: 0144-3585

Article
Publication date: 11 April 2022

Junshan Hu, Xinyue Sun, Wei Tian, Shanyong Xuan, Yang Yan, Wang Changrui and Wenhe Liao

Aerospace assembly demands high drilling position accuracy for fastener holes. Hole position error correction is a key issue to meet the required hole position accuracy…

Abstract

Purpose

Aerospace assembly demands high drilling position accuracy for fastener holes. Hole position error correction is a key issue to meet the required hole position accuracy. This paper aims to propose a combined hole position error correction method to achieve high positioning accuracy.

Design/methodology/approach

The bilinear interpolation surface function based on the shape of the aerospace structure is capable of dealing with position error of non-gravity deformation. A gravity deformation model is developed based on mechanics theory to efficiently correct deformation error caused by gravity. Moreover, three solution strategies of the average, least-squares and genetic optimization algorithms are used to solve the coefficients in the gravity deformation model to further improve position accuracy and efficiency.

Findings

Experimental validation shows that the combined position error correction method proposed in this paper significantly reduces the position errors of fastener holes from 1.106 to 0.123 mm. The total position error is reduced by 43.49% compared with the traditional mechanics theory method.

Research limitations/implications

The position error correlation method could reach an accuracy of millimeter or submillimeter scale, which may not satisfy higher precision.

Practical implications

The proposed position error correction method has been integrated into the automatic drilling machine to ensure the drilling position accuracy.

Social implications

The proposed position error method could promote the wide application of automatic drilling and riveting machining system in aerospace industry.

Originality/value

A combined position error correction method and the complete roadmap for error compensation are proposed. The position accuracy of fastener holes is reduced stably below 0.2 mm, which can fulfill the requirements of aero-structural assembly.

Article
Publication date: 26 July 2013

Alessandro Antimiani and Valeria Costantini

The purpose of this paper is to analyse the role of the enlargement process of the European Union as a factor fostering international competitiveness of EU Member States…

Abstract

Purpose

The purpose of this paper is to analyse the role of the enlargement process of the European Union as a factor fostering international competitiveness of EU Member States. The paper argues that the economic integration process has reduced the technological gap between old and new EU Member States, and this pattern of technological innovation can partially explain the strong impulse on the export dynamics of European countries.

Design/methodology/approach

The paper builds an augmented gravity model by including the role of technological innovation, proxied by the stock of knowledge at the sector level. The authors gather together information on patents applied to international offices and bilateral export flows available from COMTRADE dataset.

Findings

By using a dynamic panel data estimator the authors find three main empirical evidences. First, the enlargement process has produced an overall larger positive impact on export flows for new Members than for old ones, and more importantly that sectors with the higher technological content have received the strongest impulse. Second, the augmented gravity model allows shaping the crucial role of technological innovation in fostering export competitiveness. Third, this impact seems to be stronger for old EU Member States than for new ones.

Research limitations/implications

The major limitation concerns time span adopted in this work. By expanding the dataset to further years it could be possible to better disentangle the effects also related to the new wave of the EU enlargement.

Social implications

The policy implication derived is that the more the new EU Members catch up technologically as a result of the integration process, the more they will benefit in terms of economic development.

Originality/value

The major originality of this paper is the construction of an augmented gravity model by including the role of technological innovation, applied to distinguished manufacturing sectors in a dynamic panel setting.

Details

Journal of Economic Studies, vol. 40 no. 3
Type: Research Article
ISSN: 0144-3585

Keywords

Article
Publication date: 3 November 2020

Gour Gobinda Goswami and Nisit Panthamit

Political risk factors play a pivotal role in determining the bilateral trade flow of Asian countries in general and the Association for Southeast Asian Nations (ASEAN…

Abstract

Purpose

Political risk factors play a pivotal role in determining the bilateral trade flow of Asian countries in general and the Association for Southeast Asian Nations (ASEAN) countries in particular. The main purpose of this research paper is to examine the impact of disaggregated political risk in lowering the bilateral trade flow of Thailand, a prominent member of ASEAN, vis-à-vis her 132 trading partners.

Design/methodology/approach

Using panel data of Thailand with her partner countries for the period 1984–2015, this paper uses four different panel specifications named pooled ordinary least squares and random effects estimations (estimated generalized least squares estimation) of three types by controlling for cross-sectional heteroscedasticity, time-wise heteroscedasticity and contemporaneous correlation.

Findings

Holding other gravity-based determinants constant, for one unit increase in the ranking of indicator of military in politics at home and abroad, trade flow decreases by 5–9% of the total trade flow of Thailand per year. For other types of political risks like government instability at home and abroad, difficulties in investment profile at home and abroad and internal and external conflict at home and abroad, the decrease is also substantial and most statistically significant. The magnitude of loss due to the military channel at home and abroad can amount to US$9.38–US$16.88 bn per year for Thailand, after controlling for other gravity variables.

Research limitations/implications

The reasons for risk originating from different political channels could be explored at the regional or global level to understand their global and local dimensions.

Practical implications

Policymakers should attempt to resolve the political risks at home and abroad in an amicable manner, through dialogue, so that bilateral trade flow is not inhibited.

Social implications

By taking economic reforms only, the trading problem cannot be resolved until and unless Thailand involves her society, politics and administrative mechanisms in a conducive manner to facilitate her trade. A dialogue among bureaucracy, political authority and military is beneficial in mitigating political risks.

Originality/value

The paper is unique in the sense that it makes a solid attempt to identify the potential channels of disaggregated political risk in affecting trade flow negatively, in a gravity framework, by controlling for different kinds of error structure.

Details

International Journal of Emerging Markets, vol. 17 no. 2
Type: Research Article
ISSN: 1746-8809

Keywords

Article
Publication date: 10 November 2020

Sudeshna Ghosh

This study attempts to explore the determinants of tourism demand that impact tourist arrivals in Australia from Asia using an augmented panel gravity model.

Abstract

Purpose

This study attempts to explore the determinants of tourism demand that impact tourist arrivals in Australia from Asia using an augmented panel gravity model.

Design/methodology/approach

The augmented panel gravity model was utilised to analyse the demand for Australian tourism from 15 major countries of Asia over the period 1991 to 2018. Tourist arrivals were the dependent variable while per capita gross domestic product (GDP) and weighted distance were important explanatory variables. Further other indicators like population, money supply, globalisation, price index, exchange rate, uncertainty and two dummy variables were added as control variables.

Findings

The results demonstrate based on the novel methodology of Pesaran (2006), namely CCE (common correlated effects) that tourist arrivals are impacted positively and significantly by per capita GDP of both the country of origin and destination country, globalisation also impacts tourist flows positively. However, tourist arrivals are adversely affected by distance and prices confirming the economic theory.

Originality/value

Gravity models have been intensively used in the recent literature on tourism; however, this study has attempted to explore tourism demand from Asia into Australia which is indeed an unexplored area further the study has used the CCE methodology which takes care of the problems of cross-sectional dependence unlike the earlier methods widely used in the literature like the DOLS and the FMOLS. Last by utilising a wide-ranging set of macro factors the study contributes a novel assessment to the recent literature on tourism demand model.

Details

Journal of Economic Studies, vol. 48 no. 7
Type: Research Article
ISSN: 0144-3585

Keywords

Book part
Publication date: 18 August 2006

Diego Agudelo, Galia Julieta Benítez and Lawrence S. Davidson

This study presents evidence of increasing regionalization of international trade among 10 South American countries from 1980 to 2001. Regionalization of trade in South…

Abstract

This study presents evidence of increasing regionalization of international trade among 10 South American countries from 1980 to 2001. Regionalization of trade in South America is best described as an increasing trade among Spanish-speaking countries and increasing trade within the two regional agreements, the Andean Community and Mercosur. There is also evidence of border erosion in the continent, especially among the Mercosur members. These results emerge from a simple statistical analysis and are also economically significant when tested in a consistent gravity equation that controls for a set of macroeconomic and geographic variables.

Details

Regional Economic Integration
Type: Book
ISBN: 978-0-76231-296-2

Article
Publication date: 14 October 2013

Wen Yu, Xiaoou Li and Roberto Carmona

– This paper aims to address a new iterative tuning method of PID control for robot manipulators.

Abstract

Purpose

This paper aims to address a new iterative tuning method of PID control for robot manipulators.

Design/methodology/approach

This tuning method uses several properties of the robot control, such as any PD control can stabilize a robot in regulation case, the closed-loop system of PID control can be approximated by a linear system, the control torque to the robot manipulator is linearly independent of the robot dynamic.

Findings

Compared with the other PID tuning methods, this novel method is simple, systematic, and stable. The transient properties of this PID control are better than the other normal PID controllers.

Originality/value

In this paper, a new systematic tuning method for PID control is proposed. The paper applies this method on an upper limb exoskeleton, and real experiment results give validation of our PID tuning method.

Details

Industrial Robot: An International Journal, vol. 40 no. 6
Type: Research Article
ISSN: 0143-991X

Keywords

Article
Publication date: 7 January 2019

Bikash Ranjan Mishra and Pabitra Kumar Jena

The purpose of this paper is to examine the determinants of foreign direct investment (FDI) flows from some leading developed countries (the USA, Japan, Germany, the…

Abstract

Purpose

The purpose of this paper is to examine the determinants of foreign direct investment (FDI) flows from some leading developed countries (the USA, Japan, Germany, the Netherlands, the UK and France) into major four Asian economies (China, Korea, India and Singapore).

Design/methodology/approach

Using one basic and four augmented versions of gravity model technique, the authors tried to examine the determinants of bilateral FDI flows in four major Asian economies. The study used World Development Indicators, CEPII, KOF and Heritage Foundation data for period 2001–2012.

Findings

The results revealed that besides the market size for host and source country, other criteria such as distance, common language and common border also influence foreign investors. Other macroeconomic factors such as inflation rate and real interest rate are among the key factors that attract more FDI. In addition to economic factors, institutional and infrastructural factors such as telecommunication, degree of openness, index of globalisation and index of economic freedom also stimulate the international investors from the developed world to the major Asian countries.

Research limitations/implications

It is altogether possible that only a set of home country specific characteristics or host country specific characteristics does not matter when determining FDI. Most empirical studies using indices such as the index of globalisation and economic freedom are subject to certain methodological limitations such as model selection, parameter heterogeneity, outliers and moral hazard.

Practical implications

More distance between the host and source country would result in less FDI flows due to more managerial and raw material supply chain cost. Similarly, more gross domestic product (GDP) and per capita income (PCI) are leading to more FDI flows into Asian economics. Therefore, major Asian economies should frame their economic policies in such a manner where these counties can strengthen their GDP as well as PCI. Furthermore, above countries should open its economy more and more for better FDI flows as it seems that economic globalisation and economic freedom are major determinants of bilateral FDI flows. The negative impact of inflation and interest rate should be controlled.

Social implications

From policy perspective, higher scores of economic, social and political globalisation also attract high FDI to the host country. On the same line higher scores in economic freedom mean that less restrictions in terms of economic policies and the policy environment are conducive for free trade and resource transfers. Higher scores in trade freedom, investment freedom and freedom from corruptions also show more developed and conducive policy environment. In the same reasoning higher scores in the composite index of economic freedom which takes information from trade freedom, investment freedom and freedom from corruption and others also encourage flow of FDI in to the host country.

Originality/value

This is the first paper which combines the globalisation index, economic freedom index and distance along with some major macroeconomic variables.

Details

Journal of Economic Studies, vol. 46 no. 1
Type: Research Article
ISSN: 0144-3585

Keywords

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