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Article
Publication date: 24 June 2021

Jiaqi Zhang, Ming Cong, Dong Liu, Yu Du and Hongjiang Ma

The purpose of this paper is to use a simple method to enhance the ability of lower limb exoskeletons to restore balance under large interference conditions and to solve the…

224

Abstract

Purpose

The purpose of this paper is to use a simple method to enhance the ability of lower limb exoskeletons to restore balance under large interference conditions and to solve the problem that biped robot stability criterion cannot be fully applied to the underactuated lower limb exoskeletons.

Design/methodology/approach

The method used in this paper is to construct an underactuated lower extremity exoskeleton ankle joint with a torsion spring. Based on the constructed exoskeleton, the linear inverted torsion spring pendulum model is proposed, and the traditional capture point (CP) concept is optimized.

Findings

The underactuated exoskeleton ankle joint with torsion springs, combined with the improved CP concept, can effectively reduce the forward stepping distance under the same interference condition, which is equivalent to enhancing the balance ability of the lower extremity exoskeleton.

Originality/value

The contribution of this paper is to enhance the balance ability of the exoskeleton of the lower limbs under large interference conditions. The torsion spring is used as the exoskeleton ankle joint, and the traditional CP concept is optimized according to the constructed exoskeleton.

Details

Assembly Automation, vol. 41 no. 4
Type: Research Article
ISSN: 0144-5154

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Article
Publication date: 17 September 2024

Jiao Ge, Jiaqi Zhang, Daheng Chen and Tiesheng Dong

The purpose of this paper is to actively calibrate power density to match the application requirements with as small an actuator as possible. So, this paper introduces shape…

42

Abstract

Purpose

The purpose of this paper is to actively calibrate power density to match the application requirements with as small an actuator as possible. So, this paper introduces shape memory alloy to design variable stiffness elements. Meanwhile, the purpose of this paper is also to solve the problem of not being able to install sensors on shape memory alloy due to volume limitations.

Design/methodology/approach

This paper introduces the design, modeling and control process for a variable stiffness passive ankle exoskeleton, adjusting joint stiffness using shape memory alloy (SMA). This innovative exoskeleton aids the human ankle by adapting the precompression of elastic components by SMA, thereby adjusting the ankle exoskeleton’s integral stiffness. At the same time, this paper constructs a mathematical model of SMA to achieve a dynamic stiffness adjustment function.

Findings

Using SMA as the driving force for stiffness modification in passive exoskeletons introduces several distinct advantages, inclusive of high energy density, programmability, rapid response time and simplified structural design. In the course of experimental validation, this ankle exoskeleton, endowed with variable stiffness, proficiently executed actions like squatting and walking and it can effectively increase the joint stiffness by 0.2 Nm/Deg.

Originality/value

The contribution of this paper is to introduce SMA to adjust the stiffness to actively calibrate power density to match the application requirements. At the same time, this paper constructs a mathematical model of SMA to achieve a dynamic stiffness adjustment function.

Details

Robotic Intelligence and Automation, vol. 44 no. 6
Type: Research Article
ISSN: 2754-6969

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Article
Publication date: 8 February 2022

Jiaqi Zhang, Ming Cong, Dong Liu, Yu Du and Hongjiang Ma

This paper aims to get rid of the traditional basic principle of using the motor as the variable stiffness drive source, simplify the structure of the exoskeleton and reduce the…

730

Abstract

Purpose

This paper aims to get rid of the traditional basic principle of using the motor as the variable stiffness drive source, simplify the structure of the exoskeleton and reduce the quality of the exoskeleton. This paper proposes to use shape memory alloys (SMA) as the variable stiffness drive source.

Design/methodology/approach

In this study, SMA is used to construct the active variable stiffness unit, the Brinson constitutive model is used to establish a dynamic model to control the active variable stiffness unit and the above active variable stiffness unit is used to realize the force control function and construct a lightweight, variable stiffness knee exoskeleton.

Findings

The dynamic model constructed in this paper can preliminarily describe the phase transformation process of the active variable stiffness unit and realize the variable stiffness function of the knee exoskeleton. The variable stiffness exoskeleton can effectively reduce the driving error under the high-speed walking condition.

Originality/value

The contribution of this paper is to combine SMAs to construct an active variable stiffness unit, build a dynamic model for controlling the active variable stiffness unit and construct a lightweight, variable stiffness knee exoskeleton.

Details

Industrial Robot: the international journal of robotics research and application, vol. 49 no. 5
Type: Research Article
ISSN: 0143-991X

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Article
Publication date: 9 August 2022

Dawei Chen, Jianliang Zhou, Pinsheng Duan and Jiaqi Zhang

The outbreak of COVID-19 pandemic has posed severe challenges to infrastructure construction in China. Particularly, the complex technology and high process uncertainty of deep…

640

Abstract

Purpose

The outbreak of COVID-19 pandemic has posed severe challenges to infrastructure construction in China. Particularly, the complex technology and high process uncertainty of deep foundation pit construction make its safety risk identification a challenging issue of general concern. To address these challenges, Building Information Modeling (BIM) can be used as an important tool to enhance communication and decision-making among stakeholders during the pandemic. The purpose of this study is to propose a knowledge management and BIM-integrated safety risk identification method for deep foundation pit construction to improve the management efficiency of project participants.

Design/methodology/approach

This paper proposes a risk identification method that integrates BIM and knowledge management for deep foundation pit construction. In the framework of knowledge management, the topological relationships between objects in BIM are extracted and visualized in the form of knowledge mapping. After that, formal expressions of codes are established to realize the structured processing of specification provisions and special construction requirements. A comprehensive plug-in for deep foundation pit construction is designed based on the BIM software.

Findings

The proposed method was verified by taking a sub-project in deep foundation pit project construction as an example. The result showed the new method can make full use of the existing specification and special engineering requirements knowledge. In addition, the developed visual BIM plug-in proves the feasibility and applicability of the proposed method, which can help to increase the risk identification efficiency and refinement.

Originality/value

The deep foundation pit safety risk identification is challenged by the confusion of deep foundation pit construction safety knowledge and the complexity of the BIM model. By establishing the standardized expression of normative knowledge and special construction requirements, the efficiency and refinement of risk identification are improved while ensuring the comprehensiveness of results. Moreover, the topology-based risk identification method focuses on the project objects and their relations in the way of network, eliminating the problem of low efficiency from the direct BIM-based risk identification method due to massive data.

Details

Engineering, Construction and Architectural Management, vol. 30 no. 8
Type: Research Article
ISSN: 0969-9988

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Article
Publication date: 9 June 2023

Shucai Yang, Shiwen Xing, Yang Yu, Pei Han, Chaoyang Guo and Lukai Liu

It was verified that the micro-texture in the front and back of the tool at the same time had a positive effect on improving the milling behavior and surface quality of the tool…

104

Abstract

Purpose

It was verified that the micro-texture in the front and back of the tool at the same time had a positive effect on improving the milling behavior and surface quality of the tool. The purpose of this study is to explore the rationality of simultaneous placement of micro-textures on the front and rear surfaces of ball-end milling cutters, analyze the influence of micro-texture parameters on tool milling behavior and workpiece surface quality, reveal its internal mechanism, and obtain the best micro-texture parameters by optimization.

Design/methodology/approach

First, the mechanism of micro-texture is studied based on the energy loss model. Second, the orthogonal experiment is designed to analyze the influence of micro-texture parameters on tool milling behavior and reveal its mechanism by combining simulation technology and cutting experiment. Finally, the parameters are optimized based on the artificial bee colony algorithm.

Findings

The results show that the simultaneous placement of micro-texture on the rake face and flank face of the tool has a positive effect on improving the milling behavior and surface quality of the tool. Taking milling force, tool wear and surface roughness as the evaluation criteria, the optimal parameter combination is obtained: the rake face micro-texture diameter is 50 µm, the distance from the micro-texture is 200 µm and the distance from the cutting edge is 110 µm; the diameter of the micro-textured flank is 40 µm, the distance from the micro-texture is 170 µm and the distance from the cutting edge is 130 µm.

Originality/value

Taking milling force, tool wear and surface roughness as the evaluation criteria, the optimal parameter combination is obtained: the rake face micro-texture diameter is 50 µm, the distance from the micro-texture is 200 µm and the distance from the cutting edge is 110 µm; the diameter of the micro-textured flank is 40 µm, the distance from the micro-texture is 170 µm and the distance from the cutting edge is 130 µm, which provides theoretical support for the further study of the micro-textured tool.

Peer review

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-01-2023-0022/

Details

Industrial Lubrication and Tribology, vol. 75 no. 5
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 5 October 2020

Harish Kumar Banga, Parveen Kalra, Rajendra M. Belokar and Rajesh Kumar

The purpose of this study is improvement of human gait by customized design of ankle foot orthosis (AFO). An has been the most frequently used orthosis in children with cerebral…

904

Abstract

Purpose

The purpose of this study is improvement of human gait by customized design of ankle foot orthosis (AFO). An has been the most frequently used orthosis in children with cerebral palsy. AFOs are designed to boost existing features or to avoid depression or traumatize muscle contractures. The advantages of AFO’s utilized for advancement in human walk attributes for the improvement in foot deformities patients or youngsters with spastic loss of motion. In this research on the customized design of AFO's to improve gait, there are limitations during walking of foot drop patients. In children with foot drops, specific AFOs were explicitly altered to improve parity and strength which are beneficial to walking positions.

Design/methodology/approach

This study proposes the customized design of AFOs using computerized and additive manufacturing for producing advances to alter the design and increase comfort for foot drop patients. Structuring the proposed design fabricated by using additive manufacturing and restricted material, the investigation was finalized at the Design Analysis Software (ANSYS). The system that performs best under investigation can additionally be printed using additive manufacturing.

Findings

The results show that the customized design of AFOs meets the patient’s requirements and could also be an alternative solution to the existing AFO design. The biomechanical consequences and mechanical properties of additive manufactured AFOs have been comparable to historically synthetic AFOs. While developing the novel AFO designs, the use of 3D printing has many benefits, including stiffness and weight optimization, to improve biomechanical function and comfort. To defeat the issues of foot drop patients, a customized AFO is used to improve the human gait cycle with new material and having better mechanical properties.

Originality/value

This research work focuses on the biomechanical impacts and mechanical properties of customized 3D-printed AFOs and compares them to traditionally made AFOs. Customized AFO design using 3D printing has numerous potential advantages, including new material with lightweight advancement, to improve biomechanical function and comfort. Normally, new applications mean an incremental collection of learning approximately the behavior of such gadgets and blending the new design, composite speculation and delivered substance production. The test results aim to overcome the new AFO structure issues and display the limited components and stress examination. The outcome of the research is the improved gait cycle of foot drop patients.

Details

Rapid Prototyping Journal, vol. 26 no. 10
Type: Research Article
ISSN: 1355-2546

Keywords

Available. Open Access. Open Access
Article
Publication date: 13 November 2023

Ming Gao, Anhui Pan, Yi Huang, Jiaqi Wang, Yan Zhang, Xiao Xie, Huanre Han and Yinghua Jia

The type 120 emergency valve is an essential braking component of railway freight trains, but corresponding diaphragms consisting of natural rubber (NR) and chloroprene rubber…

433

Abstract

Purpose

The type 120 emergency valve is an essential braking component of railway freight trains, but corresponding diaphragms consisting of natural rubber (NR) and chloroprene rubber (CR) exhibit insufficient aging resistance and low-temperature resistance, respectively. In order to develop type 120 emergency valve rubber diaphragms with long-life and high-performance, low-temperatureresistant CR and NR were processed.

Design/methodology/approach

The physical properties of the low-temperature-resistant CR and NR were tested by low-temperature stretching, dynamic mechanical analysis, differential scanning calorimetry and thermogravimetric analysis. Single-valve and single-vehicle tests of type 120 emergency valves were carried out for emergency diaphragms consisting of NR and CR.

Findings

The low-temperature-resistant CR and NR exhibited excellent physical properties. The elasticity and low-temperature resistance of NR were superior to those of CR, whereas the mechanical properties of the two rubbers were similar in the temperature range of 0 °C–150 °C. The NR and CR emergency diaphragms met the requirements of the single-valve test. In the low-temperature single-vehicle test, only the low-temperature sensitivity test of the NR emergency diaphragm met the requirements.

Originality/value

The innovation of this study is that it provides valuable data and experience for future development of type 120 valve rubber diaphragms.

Details

Railway Sciences, vol. 3 no. 1
Type: Research Article
ISSN: 2755-0907

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Article
Publication date: 6 January 2023

Xin Liu, Chenghu Zhang and Jiaqi Wu

The purpose of this study is to investigate the influencing mechanism of consumers' continuous purchase intention toward the subscriber-based knowledge payment platforms (SBKPPs).

929

Abstract

Purpose

The purpose of this study is to investigate the influencing mechanism of consumers' continuous purchase intention toward the subscriber-based knowledge payment platforms (SBKPPs).

Design/methodology/approach

This study obtained 226 valid samples through questionnaire surveys and used partial least square structural equation modeling (PLS-SEM) and fuzzy-set qualitative comparative analysis (fsQCA) methods to elucidate the complex causal patterns of consumers' continuous purchase intention toward the SBKPPs.

Findings

The findings revealed that perceived utilitarian value, perceived hedonic value and perceived social value directly affected consumers' continuous purchase intention, while content quality and service quality indirectly affected consumers' continuous purchase intention. In addition, this study also demonstrated that all factors must be combined to play a role, and there exist four configurations resulting in consumers' continuous purchase intention toward the SBKPPs.

Research limitations/implications

The results can help researchers and practitioners better understand the causal patterns of consumers' continuous purchase intention toward the SBKPPs.

Originality/value

This study contributes to the knowledge payment literature by investigating consumers' continuous purchase intention toward the SBKPPs. This study also provides practical enlightenment for the SBKPPs' marketing.

Details

Aslib Journal of Information Management, vol. 76 no. 2
Type: Research Article
ISSN: 2050-3806

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Article
Publication date: 14 June 2022

Hui Liu, Jiaqi Ning, Yue Zhang and Junrui Zhang

In an effort to make audit reports more informative to users, the Public Company Accounting Oversight Board and the International Auditing and Assurance Standards Board adopted a…

883

Abstract

Purpose

In an effort to make audit reports more informative to users, the Public Company Accounting Oversight Board and the International Auditing and Assurance Standards Board adopted a standard that requires auditors to disclose key audit matters (KAMs). This paper aims to explore the impact of the risk information provided by KAMs on corporate debt contracting.

Design/methodology/approach

In China, the KAM standard went into effect for A + H cross-listing companies in 2017 and became mandatory for all listed companies in 2018. This study takes this as an exogenous shock to examine the impact of the KAM disclosures on debt contracting. This study also designs a path analysis to open the “black box” between the risk information in KAMs and the risk perception of creditors. Moreover, This study conducts a textual analysis on the KAMs information based on samples after the release of the KAM standard.

Findings

This study conducts difference-in-difference tests and find that the KAM disclosures decrease interest rates and increase the proportion of long-term debt. Path analyses reveal that the KAM disclosures lead to more favorable debt characteristics through decreasing information asymmetry. This study also finds that the more KAMs are disclosed, the more favorable debt characteristics are and that different categories of KAMs have different effects on debt contracting.

Originality/value

This paper highlights the benefits of KAM disclosures, which are consistent with the convergence argument of risk information disclosures. Investors’ reactions to KAMs are mixed because of the differences in how professional investors and nonprofessional investors interpret information. This study provides evidence of incrementally informative nature of KAMs from the perspective of debt holders, who are professional information users.

Details

Managerial Auditing Journal, vol. 37 no. 6
Type: Research Article
ISSN: 0268-6902

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Article
Publication date: 2 May 2017

Qihui Chen, Jingqin Xu, Jiaqi Zhao and Bo Zhang

The purpose of this paper is to estimate the returns to rural schooling in China, addressing both endogeneity in rural individuals’ schooling and self-selection into off-farm work.

452

Abstract

Purpose

The purpose of this paper is to estimate the returns to rural schooling in China, addressing both endogeneity in rural individuals’ schooling and self-selection into off-farm work.

Design/methodology/approach

This paper exploits geographical proximity to rural secondary schools to create instrumental variables (IV) for individuals’ years of schooling. It addresses both endogenous schooling and self-selection using the two-step procedure developed in Wooldridge (2002, p. 586).

Findings

The preferred IV estimate of schooling returns, 7.6 percent, is considerably higher than most previous estimates found in rural China.

Originality/value

This paper is among the few papers that examine returns to rural schooling in China while simultaneously addressing both endogeneity in individuals’ schooling and self-selection into off-farm work. Its findings suggest that rural education in China is potentially able to generate a respectable level of economic returns if policies are designed to provide greater school accessibility to rural individuals.

Details

China Agricultural Economic Review, vol. 9 no. 2
Type: Research Article
ISSN: 1756-137X

Keywords

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