Changlong Ye, Yunfei Du, Suyang Yu, Qiang Zhao and Chunying Jiang
With the development of automation technology, the accuracy, bearing capacity and self-adaptation requirements of wheeled mobile robots are more and more demanding under various…
Abstract
Purpose
With the development of automation technology, the accuracy, bearing capacity and self-adaptation requirements of wheeled mobile robots are more and more demanding under various complex conditions, which will urge designers such shortcomings as the low accuracy, poor flexibility and weak obstacle crossing ability of traditional heavy haul vehicles and improve the wear resistance and bearing capacity of traditional omnidirectional wheels.
Design/methodology/approach
The optimal configuration for heavy payload transportation is obtained by building sliding friction consumption model of traditional wheels with different driving types based on Hertz tangential contact theory. The heavy payload omnidirectional wheel with a double-wheel steering and a coupled differential wheel driving is designed with the optimal configuration. The wheel consists of a differential gear train unit and a nonindependent suspension unit. Kinematics model of the wheel is established and relative parameters are optimized.
Findings
The prototype experiments show that the wheel has higher motion accuracy and environment adaptability. The results are consistent with the theoretical calculation, which show that the accuracy is more than 50% higher than that of differential prototype. The motion stability and the accuracy of the coupled differential omnidirectional wheel are better than those of the traditional omnidirectional wheels during the moving and obstacle crossing process under complex conditions, which verifies the correctness and advantages of the design.
Originality/value
Aiming at the specific application of heavy payload omnidirectional transportation, a new omnidirectional mobile mechanism with a two-wheel coupling drive structure and an adaptive mechanism is proposed. The simulation and experimental results show that it can realize the high-precision heavy-load omnidirectional movement, the effective contact with the ground and improve the adaptability to the rugged ground. It is flexible, simple and modular and can be widely applied to transportation, exploration, detection and other related industrial fields.
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Changlong Ye, Yunfei Zang, Suyang Yu and Chunying Jiang
The purpose of this paper is to demonstrate a multipurpose inspection robot that can both walk on the ground and climb on poles. The structure design, size optimization…
Abstract
Purpose
The purpose of this paper is to demonstrate a multipurpose inspection robot that can both walk on the ground and climb on poles. The structure design, size optimization, kinematics analysis, experiment and arithmetic of the robot are discussed in the paper.
Design/methodology/approach
The robot consists of three adjustable modules and a two-degree-of-freedom parallel mechanism in tandem, and the wheel-finger mechanism of each module can realize wheel-finger opening and closing for fast movement and obstacle crossing. This paper uses geometric analysis and simulation analysis to derive size optimization, and vector coordinate method to derive kinematics. Finally, the experiment is carried out by simulating the working environment of the robot.
Findings
The robot can realize ground walking and ground turning through the robot entity prototype experiment on the built working environment and efficiently realize 0°–90° pole climbing by the assemble design, optimization and machining. In addition, the robot can also smoothly complete the state transition process from 0° ground to 90° pole climbing. Furthermore, the robot shows good environmental self-adaptation and can complete daily inspection work.
Originality/value
The robot can pitch and yaw at a large angle and has six-legged characteristics. It is a multipurpose inspection robot that can walk on the ground and climb on poles. And through structure design, size optimization, kinematics analysis and simulation, the existing robots’ common shortcomings such as poor barrier-crossing ability and poor environmental adaptability are solved.
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Changlong Ye, Yingxin Sun, Suyang Yu, Jian Ding and Chunying Jiang
The mechanical properties between wheel and ground will affect the motion performance of wheeled omnidirectional mobile robot (OMR). MY3 wheel is an omnidirectional wheel. This…
Abstract
Purpose
The mechanical properties between wheel and ground will affect the motion performance of wheeled omnidirectional mobile robot (OMR). MY3 wheel is an omnidirectional wheel. This paper aims to analyze the contact mechanical characteristics between MY3 wheel and ground to improve the motion accuracy of an omnidirectional mobile platform with MY3 wheel (MY3-OMR).
Design/methodology/approach
This method takes MY3 wheel as the research objective. The normal and tangential contact mechanics model and rolling contact mechanics model of MY3 wheel are established by analyzing the structure of MY3 wheel, and thereby, the slip ratio of MY3 wheel in the process of motion is calculated. The kinematics model of MY3-OMR is optimized by taking the slip ratio as the optimization parameter that aims to improve motion accuracy of MY3-OMR.
Findings
The correctness of the mechanical analysis and the feasibility of the method are verified by the MY3-OMR prototype. Let MY3-OMR move along the set circular trajectory and square trajectory, and the error between the motion trajectory before and after optimization and the standard trajectory is obtained. It illustrates that the error in the square trajectory is reduced by 1.5%, and the circular trajectory error is reduced by 2%; therefore, the method is effective.
Originality/value
A method based on contact mechanics is proposed and verified. Through the establishment of wheel-ground contact mechanics model to optimize MY3-OMR kinematics model, and thereby, the motion accuracy of MY3-OMR is improved, which lays a foundation for MY3-OMR engineering application.
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This study aims to revisit the empirical debate about the asymmetric relationship between oil prices, energy consumption, CO2 emissions and economic growth in a panel of 184…
Abstract
Purpose
This study aims to revisit the empirical debate about the asymmetric relationship between oil prices, energy consumption, CO2 emissions and economic growth in a panel of 184 countries from 1981 to 2020.
Design/methodology/approach
A relatively new research method, the PVAR system GMM, is applied.
Findings
The outcome of the PVAR system GMM model at the group level in the study suggests that oil prices exert a positive but statistically insignificant effect on economic growth. Energy consumption is inversely related to economic growth but statistically significant, and the correlation between CO2 emissions and economic growth is negative but statistically insignificant. The Granger causality test indicates that oil prices, CO2 emissions, oil rents, energy consumption and savings jointly Granger-cause economic growth. A unidirectional causality runs from energy consumption, savings and economic growth to oil prices. At countries’ income grouping levels, oil prices, oil rent, CO2 emissions, energy consumption and savings jointly Granger-cause economic growth for the high-income and upper-middle-income countries groups only, while those variables did not jointly Granger-cause economic growth for the low-income and lower-middle-income countries groups. The modulus emanating from the eigenvalue stability condition with the roots of the companion matrix indicates that the model is stable. The results support the asymmetric impacts of oil prices on economic growth and aid policy formulation, particularly the cross-country disparities regarding the nexus between oil prices and growth.
Originality/value
From a methodological perspective, to the best of the author’s knowledge, the study is the first attempt to use the PVAR system GMM and such a large sample group of 184 economies in the post-COVID-19 era to examine the impacts of oil prices on countries’ growth while controlling for other crucial variables, which is noteworthy. Two, using the World Bank categorisation of countries according to income groups, the study adds another layer of contribution to the literature by decomposing the 184 sample economies into four income groups: high-income, low-income, upper-middle-income and lower-middle-income groups to investigate the potential for asymmetric effects of oil prices on growth, the first of its kind in the post-COVID-19 period.
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The main purpose of paper is to analyse the political, military and strategic significance of China’s rising power and its influence on Sino-Indian relations, while addressing the…
Abstract
Purpose
The main purpose of paper is to analyse the political, military and strategic significance of China’s rising power and its influence on Sino-Indian relations, while addressing the question as to why India has not been able to develop a long-term, stable and friendly relationship with China.
Design/methodology/approach
The paper is structured as follows: historical overview of India-China relations; various tools of China’s policy in Indian sub-continent; and India’s response. The paper employs a qualitative analysis of secondary literature, with media reports, official documents and public statements providing important sources for understanding the dynamics underlying bilateral relationship.
Findings
India needs to be prepared to face challenges as China’s charm offensive in India’s neighbourhood is primarily aimed at establishing a new Asian order in which Beijing would play the leading role. As China institutionalizes its military presence in South Asia and the Indian Ocean, India should adopt an innovative response mechanism, also involving counter-presence in areas considered China’s traditional sphere of influence.
Originality/value
The primary value of the paper lies in the fact that it covers most of the key dimensions of bilateral ties that impair a stable relationship between India and China. A proper understanding of the dynamics underlying bilateral ties may help the policymakers, scholars and academics to suggest ways to reduce sources of tensions, while also helping the Indian Government to prepare effective countermeasures.