Yunfei Dong, Tianyu Ren, Ken Chen and Dan Wu
This paper aims to improve the accuracy of robot payload identification and decrease the complexity in its industrial application by developing a new method based on the actuator…
Abstract
Purpose
This paper aims to improve the accuracy of robot payload identification and decrease the complexity in its industrial application by developing a new method based on the actuator current.
Design/methodology/approach
Instead of previous general robot dynamic modeling of the actuators, links, together with payload inertial parameters, the paper discovers that the difference of the actuator torque between the robot moving along the same trajectory with and without carrying payload can be described as a function of the payload inertial parameters directly. Then a direct dynamic identification model of payload is built, a set of specialized novel exciting trajectories are designed for accurate identification and the least square method is applied for the estimation of the load parameters.
Findings
The experiments confirm the effectiveness of the proposed method in robot payload identification. The identification accuracy is greatly improved compared with that of existing methods based on the actuator current and is close to the accuracy of the methods that direct use the wrist-mounted force-torque sensor.
Practical implications
As the provided experiments indicate, the proposed method expands the application range and greatly improves the accuracy, hence making payload identification fully operational in the industrial application.
Originality/value
The novelty of such an identification method is that it does not require the rotor inertias and inertial parameters of links as a prior knowledge, and the specially designed trajectories provide completed decoupling of the load parameters.
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Tianyu Ren, Yunfei Dong, Dan Wu and Ken Chen
The purpose of this paper is to present a simple yet effective force control scheme for collaborative robots by addressing the problem of disturbance rejection in joint torque…
Abstract
Purpose
The purpose of this paper is to present a simple yet effective force control scheme for collaborative robots by addressing the problem of disturbance rejection in joint torque: inherent actuator flexibility and nonlinear friction.
Design/methodology/approach
In this paper, a joint torque controller with an extended state observer is used to decouple the joint actuators from the multi-rigid-body system of a constrained robot and compensate the motor friction. Moreover, to realize robot force control, the authors embed this controller into the impedance control framework.
Findings
Results have been given in simulations and experiments in which the proposed joint torque controller with an extended state observer can effectively estimate and compensate the total disturbance. The overall control framework is analytically proved to be stable, and further it is validated in experiments with a robot testbed.
Practical implications
With the proposed robot force controller, the robot is able to change its stiffness in real time and therefore take variable tasks without any accessories, such as the RCC or 6-DOF F/T sensor. In addition, programing by demonstration can be realized easily within the proposed framework, which makes the robot accessible to unprofessional users.
Originality/value
The main contribution of the presented work is the design of a model-free robot force controller with the ability to reject torque disturbances from robot-actuator coupling effect and motor friction, applicable for both constrained and unconstrained environments. Simulation and experiment results from a 7-DOF robot are given to show the effectiveness and robustness of the proposed controller.
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Yuan Liu, Chang Dong, Xianzhang Wang, Xiao Sang, Liran Ma, Xuefeng Xu and Yu Tian
The purpose of this study is to reveal the underlying mechanism in film formation of oil-in-water (O/W) emulsion.
Abstract
Purpose
The purpose of this study is to reveal the underlying mechanism in film formation of oil-in-water (O/W) emulsion.
Design/methodology/approach
This study focuses on the film forming characteristics of O/W emulsion between the surface of a steel ball and a glass disc coated with chromium. The lubricant film thicknesses of O/W emulsion with various mechanical stirring strength were discussed, which were observed by technique of relative optical interference intensity.
Findings
The authors directly observed the oil pool in the contact area, finding the size of oil pool was closely related to the film-forming ability of emulsion. Enrichment phenomenon occurs in oil pool, which was caused by phase inversion. Further investigations revealed that the emulsion is stable with strong stirring strength, resulting in a smaller oil pool size and worse film forming ability.
Originality/value
With the wide usage of O/W emulsion in both biological and industrial systems, the ability of emulsion film formation is considered as an important factor to evaluate the lubrication effectiveness.
Peer review
The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-12-2022-0354/
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Tianyu Ying, Jun Wen, Edmund Goh and Shaohua Yang
The relationship between sex and tourism remains ambiguous in the tourism literature. Few studies have examined the underlying motivations behind sex-driven travel, and little is…
Abstract
Purpose
The relationship between sex and tourism remains ambiguous in the tourism literature. Few studies have examined the underlying motivations behind sex-driven travel, and little is known about factors inhibiting tourists' procurement of commercial sex when traveling. Therefore, this study explored male Chinese tourists' perceived constraints during decision-making and developed a comprehensive scale to assess constraints to commercial sex consumption overseas.
Design/methodology/approach
Data were obtained from male Chinese tourists purchasing commercial sex while traveling overseas. This study involved a four-stage process as recommended by Churchill (1979) for scale development research. In Stage 1, preliminary items were generated through a comprehensive review of the constraints literature and in-depth interviews with 16 sex tourists, which generated an initial 26 items. During the second stage to purify the measurement items, six items were eliminated, resulting in 20 items. Stage 3 involved exploratory factor analysis (N = 275) to extract the scale's underlying factor structure. Results revealed a five-factor structure with sufficient evidence of internal reliability given Cronbach's alpha coefficients between 0.722 and 0.843. The final stage included confirmatory factor analysis (N = 259) to verify the scale's reliability and validity.
Findings
Ultimately, 20 items were developed to measure sex tourists' perceived constraints toward engaging in commercial sex services overseas based on five factors: structural constraints, intrapersonal constraints, interpersonal constraints, value conflicts and service supply–related constraints.
Originality/value
This study advances the scope of sex tourism research by verifying how these five constraints are independent, generalized and can influence the procurement of sexual services overseas. This study is the first in sex tourism research to explore the difficulties facing sex tourists. Results offer marketers important insight on how to better address these constraints while providing a safe and legal sex tourism experience.
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Tianyu Yan, Weizhe Yang, Yanyan He and Qinglong Gou
This study aims to investigate the effect of the reference quality on the optimal production strategy of a component manufacturer (CM), which mainly concerns whether to sell its…
Abstract
Purpose
This study aims to investigate the effect of the reference quality on the optimal production strategy of a component manufacturer (CM), which mainly concerns whether to sell its high quality self-branded products and whether to supply critical components to a competitive original equipment manufacturer (OEM) who produces low quality products.
Design/methodology/approach
The study considers a supply chain comprising an OEM, a CM and a third-party component manufacturer (TCM), who produces components with uncertain quality. The OEM selects a supplier between the CM and the TCM to produce products. Anticipating the OEM’s supplier selection, the CM chooses among three alternative production strategies. For each alternative strategy of the CM, the authors derive the equilibrium solutions between the OEM and the CM with or without the reference quality effect. Then, the authors obtain the effect of the reference quality on the CM by comparing the CM’s optimal strategy between the two situations.
Findings
First, the reference quality has opposite effects on the CM’s production strategy depending on the competition results. A high reference quality effect motivates the CM to solely sell the self-branded products if the OEM can always enter the final product market when purchasing from the TCM, and to sell both self-branded products and components if the OEM cannot enter the market when using the TCM’s low quality components. Second, the reference quality effect motivates the OEM to accept a higher wholesale price from the CM. Third, the reference quality effect can make the CM benefit from a more stable TCM in competition.
Originality/value
This paper first considers the impact of the reference quality effect on the CM’s production strategy. By considering consumers’ behavior in a co-opetitive supply chain, this paper contributes to both literature and practice.
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Hui Wang, Tianyu He and Chunjie Wang
In the field of planetary exploration, the legged-type lander is a common landing buffer device. There are two important performance metrics for legged-type landers: the energy…
Abstract
Purpose
In the field of planetary exploration, the legged-type lander is a common landing buffer device. There are two important performance metrics for legged-type landers: the energy absorption capacity and landing stability. In this paper, a novel method is proposed to optimize the honeycomb buffer of a legged-type lander. Optimization design variables are the dimension parameters of honeycomb and the objective functions are the evaluation parameters of the above two performance metrics.
Design/methodology/approach
A multi-body dynamic model of a lander and a finite-element model of the metal honeycomb are established. Based on the simulation results of the finite-element model and the quartic polynomial, the surrogate models are established to evaluate the energy absorption capacity of honeycomb. Considering both the multi-body dynamic model and the surrogate models, the study designed the optimization flow of dimension parameters of honeycomb. Besides, the non-dominated sorting genetic algorithm II is used for iterative calculation.
Findings
Images of surrogate models show the monotonous functional relationship between the honeycomb’s energy absorption characteristics and its dimension parameters. Optimization results show an apparent contradiction among the objective functions. Besides, according to the simulation results, this method can significantly improve the comprehensive performance of the lander.
Originality/value
The novel method can effectively reduce the cost of honeycomb compression tests and improve the lander’s design. Therefore, it can be used for optimizing buffers of other types of legged-type landers.
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Dongdong Song, Wenxiang Qin, Qian Zhou, Dong Xu and Bo Zhang
The anticorrosion coatings used in marine and atmospheric environment are subjected to many environmental factors. And the aging failure has been puzzling researchers. The purpose…
Abstract
Purpose
The anticorrosion coatings used in marine and atmospheric environment are subjected to many environmental factors. And the aging failure has been puzzling researchers. The purpose of this study is to find the correlation between the initial aging of epoxy coatings and the typical marine atmospheric environmental factors.
Design/methodology/approach
The epoxy coatings were subjected to a one-year exposure in three typical marine atmospheres. Meanwhile, principal component analysis, linear regression and Spearman and gray correlation analysis were applied to quantify the environmental characteristics and establish correlations with the coating aging.
Findings
The results indicate that the coating will undergo macroscopic fading and chalking upon exposure to the marine atmosphere, while microscopic examination reveals holes, cracks and partial peeling. The adhesion performance and electrochemical properties of the coating deteriorated with prolonged exposure, coating aging mainly occurs with the generation of O-H bonds and the breakage of molecular chains such as C-N and C-O-C. The coating was most deeply aged after exposure to the Xisha, followed by Zhoushan and finally Qingdao. Environmental factors affect the photooxidative aging and hydrolytic degradation processes of coatings and thus coating aging. To further demonstrate the correlation between environmental factors and coating aging, principal component analysis was used. The correlation model between environmental factors and coating aging was subsequently obtained. The correlation model between the rate of coating adhesion loss (E) and the comprehensive evaluation parameter of environmental factors (Z) is expressed as E = 0.142 + 0.028Z. Meanwhile, the Spearman correlation analysis and gray correlation method were used to investigate the impact of each environmental factor on coating aging. Solar irradiation, relative humidity and wetting time have the highest correlation with coating aging, which are all above 0.8 and have the greatest influence on coating aging; wind speed and temperature have the smallest correlation with coating aging, which are about 0.6 and have the least influence on coating aging.
Originality/value
This paper establishes a correlation between typical marine environmental factors and coating aging performance, which is crucial for predicting the service life of other coatings in diverse environments.
Details
Keywords
Jun Wen, Carol Chunfeng Wang, Edmund Goh, Zhaohui Su and Tianyu Ying
This paper explores the role of traditional Chinese medicine (TCM) as a tourism recovery drawcard to boost China's inbound tourism after COVID-19.
Abstract
Purpose
This paper explores the role of traditional Chinese medicine (TCM) as a tourism recovery drawcard to boost China's inbound tourism after COVID-19.
Design/methodology/approach
This paper employed a mixed method involving a cross-disciplinary literature review along with reflections from experts in TCM and health communication to inform tourism management. Specifically, this paper examines TCM and its potential benefits as a medical tourism drawcard to combat COVID-19. The selected literature focusses on the image and merits of TCM to frame how this medical philosophy can be used to position China as a tourist destination. Reflections on the use of TCM as a tourism marketing tool can guide promotional strategies from the Chinese government and destination managers during and after COVID-19.
Findings
The Chinese government, the tourism industry (e.g. destination managers), the media and tourists must focus on three aspects of the role of TCM: to provide medical benefits to travellers amid COVID-19 and beyond, elevate China as a destination for global medical tourists and be leveraged as a tool for economic recovery.
Practical implications
The paper builds a tourism recovery framework for stakeholders to adopt tailored TCM communication strategies to boost its inbound tourism programme.
Originality/value
This paper is the first academic paper to review TCM comprehensively and critically in relation to China tourism and post-COVID-19 recovery measures.
Details
Keywords
Tianyu Zhang, Hongguang Wang, Peng LV, Xin’an Pan and Huiyang Yu
Collaborative robots (cobots) are widely used in various manipulation tasks within complex industrial environments. However, the manipulation capabilities of cobot manipulation…
Abstract
Purpose
Collaborative robots (cobots) are widely used in various manipulation tasks within complex industrial environments. However, the manipulation capabilities of cobot manipulation planning are reduced by task, environment and joint physical constraints, especially in terms of force performance. Existing motion planning methods need to be more effective in addressing these issues. To overcome these challenges, the authors propose a novel method named force manipulability-oriented manipulation planning (FMMP) for cobots.
Design/methodology/approach
This method integrates force manipulability into a bidirectional sampling algorithm, thus planning a series of paths with high force manipulability while satisfying constraints. In this paper, the authors use the geometric properties of the force manipulability ellipsoid (FME) to determine appropriate manipulation configurations. First, the authors match the principal axes of FME with the task constraints at the robot’s end effector to determine manipulation poses, ensuring enhanced force generation in the desired direction. Next, the authors use the volume of FME as the cost function for the sampling algorithm, increasing force manipulability and avoiding kinematic singularities.
Findings
Through experimental comparisons with existing algorithms, the authors validate the effectiveness and superiority of the proposed method. The results demonstrate that the FMMP significantly improves the force performance of cobots under task, environmental and joint physical constraints.
Originality/value
To improve the force performance of manipulation planning, the FMMP introduces the FME into sampling-based path planning and comprehensively considers task, environment and joint physical constraints. The proposed method performs satisfactorily in experiments, including assembly and in situ measurement.