This paper aims to present an impedance control method with mixed H2/H∞ synthesis and relaxed passivity for a cable-driven series elastic actuator to be applied for physical…
Abstract
Purpose
This paper aims to present an impedance control method with mixed H2/H∞ synthesis and relaxed passivity for a cable-driven series elastic actuator to be applied for physical human–robot interaction.
Design/methodology/approach
To shape the system’s impedance to match a desired dynamic model, the impedance control problem was reformulated into an impedance matching structure. The desired competing performance requirements as well as constraints from the physical system can be characterized with weighting functions for respective signals. Considering the frequency properties of human movements, the passivity constraint for stable human–robot interaction, which is required on the entire frequency spectrum and may bring conservative solutions, has been relaxed in such a way that it only restrains the low frequency band. Thus, impedance control became a mixed H2/H∞ synthesis problem, and a dynamic output feedback controller can be obtained.
Findings
The proposed impedance control strategy has been tested for various desired impedance with both simulation and experiments on the cable-driven series elastic actuator platform. The actual interaction torque tracked well the desired torque within the desired norm bounds, and the control input was regulated below the motor velocity limit. The closed loop system can guarantee relaxed passivity at low frequency. Both simulation and experimental results have validated the feasibility and efficacy of the proposed method.
Originality/value
This impedance control strategy with mixed H2/H∞ synthesis and relaxed passivity provides a novel, effective and less conservative method for physical human–robot interaction control.
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Chengguo Zong, Zhijian Ji and Haisheng Yu
This paper aims to provide a theoretical principle for the stability control of robot climbing stairs, autonomously based on human–robot interaction. Through this research…
Abstract
Purpose
This paper aims to provide a theoretical principle for the stability control of robot climbing stairs, autonomously based on human–robot interaction. Through this research, tracked mobile robots with human-robot interaction will be extensively used in rescue in disaster, exploration on planetary, fighting in battle, and searching for survivors in collapsed buildings.
Design/methodology/approach
This paper introduces the tracked mobile robot, based on human–robot interaction, and its six moving postures. The dynamic process of climbing stairs is analyzed, and the dynamic model of the robot is proposed. The dynamic stability criterion is derived when the tracked mobile robot contacts the stairs steps in one, two and more points. A further conduction of simulation on the relationship of the traction force and bearing force vs the velocity and acceleration in the three cases was carried out.
Findings
This paper explains that the tracked mobile robot, based on human–robot interaction, can stably climb stairs so long as the velocity and acceleration satisfy the dynamic stability criterion as noted above. In addition, the experiment tests the correctness of dynamic stability analysis when the tracked mobile robot contacts the stair steps in one, two or more points.
Originality/value
This paper provides the mechanical structure and working principle of the tracked mobile robot based on human–robot interaction and proposes an identification method of dynamic stability criterion when the robot contacts the stairs steps in one, two and more points.
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Qiushi Hao, Benchen Fu, Yu Shao and Liying Wang
This study aims to explore the spatial distribution characteristics and spactial reciprocity between industrial parks (IPs) and vocational education parks (VEPs): agglomeration…
Abstract
This study aims to explore the spatial distribution characteristics and spactial reciprocity between industrial parks (IPs) and vocational education parks (VEPs): agglomeration density, functional matching, spatial organization efficiency, as well as space intensive utility. To achieve this objective, IPs and VEPs in urban centers of Jiangsu Province are selected as the objects of the study. First, spatial analysis of thermodynamic diagrams is employed in this study to qualitatively analyze the evolutionary characteristics of the spatial distribution of IPs and VEPs to explore the spatial aggregation characteristics of their clustering, integration, and comprehensive crossover. Second, a horizontal comparison of the data and indexes concerned reveals that areas with high agglomeration and functional matching exhibit a sound spatial reciprocity. Third, this study crystallizes the four structural prototpye paradigms formed during the reciprocity evolution between IPs and VEPs; it compares spatial organization efficiency, with the agglomeration–core structure ranking first, followed by the circle–core structure. Finally, SPSS is used to analyze the space intensive utility in order to verify the conclusions of qualitative analysis. The findings can comprehensively explain the regularities of the spatial distribution and reciprocity between IPs and VEPs. The findngs can also elucidate the design of regional industrial development and educational programs.
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H.S. Yu, S.W. Sloan and P.W. Kleeman
This paper presents a new finite element formulation of the upper bound theorem. The formulation uses a six‐noded linear strain triangular element. Each node has two unknown…
Abstract
This paper presents a new finite element formulation of the upper bound theorem. The formulation uses a six‐noded linear strain triangular element. Each node has two unknown velocities and each corner of a triangle is associated with a specified number of unknown plastic multiplier rates. The major advantage of using a linear strain element, rather than a constant strain element, is that the velocity field can be modelled more accurately. In addition, the incompressibility condition can be easily satisfied without resorting to special arrangements of elements in the mesh. The formulation permits kinematically admissible velocity discontinuities at specified locations within the finite element mesh. To ensure that finite element formulation of the upper bound theorem leads to a linear programming problem, the yield criterion is expressed as a linear function of the stresses. The linearized yield surface is defined to circumscribe the parent yield surface so that the solution obtained is a rigorous upper bound. During the solution phase, an active set algorithm is used to solve the resulting linear programming problem. Several numerical examples are given to illustrate the capability of the new procedure for computing rigorous upper bounds. The efficiency and accuracy of the quadratic formulation is compared with that of the 3‐noded constant strain formulation in detail.
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All countries are addressing the drastic climate changes as high priority issues. The impact of climate change on coastal land use in Taiwan has been especially severe due to the…
Abstract
All countries are addressing the drastic climate changes as high priority issues. The impact of climate change on coastal land use in Taiwan has been especially severe due to the country's long coastline. As such, developing strategies to promote the protection of coastal land is critical for the sustainable development of the land. At present, even though the central government has developed the relevant adaptation strategies and implementation plans in response to climate change. Due to the limited resources, determining which protection strategy should be implemented as a top priority will require a strategic evaluation for planning and reference purposes.
While most of the existing literature on coastal land use has been focused on the establishment of a vulnerability index along with an analysis of adaptation strategies very little of the existing literature discusses research that has been conducted in relation to an in-depth analysis of climate change and coastal land use. Therefore, this study uses the fuzzy analytic hierarchy process to conduct an exploration of coastal land use and protection strategy. The study compiled the literature and related data to establish five major assessment dimensions and 16 protection strategy evaluation indicators. After the empirical investigation and analysis, the findings demonstrated that the designation of coastal conservation areas is the most important aspect in terms of strategies to protect coastal land, followed by land subsidence control and the establishment of land disaster warning systems.
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Mian Wang and Yajing Feng
Special education in China has lagged behind regular education for many years, however, the past few decades, the government has made considerable efforts to develop and improve…
Abstract
Special education in China has lagged behind regular education for many years, however, the past few decades, the government has made considerable efforts to develop and improve the special education system. While the citizens of China have had a generic moral interest in disability since ancient times, the development of special education schools did not occur until American and European missionaries started schools for the visually and hearing impaired in the 19th century. The next major influence in the development of the special education system occurred with China’s Cultural Revolution in 1978. Interestingly, there is not any exclusive legislation on special education but in the 1980s, the government started Learning in Regular Classrooms (LRC), which is China’s version of inclusion. LRC has progressed rapidly the past two decades; however, the quality of instruction is low due to a lack of specialists, a shortage of personnel, inadequate funding, and limited technology as well as other barriers that are delineated in the chapter. The chapter emphasizes the government’s recent efforts in in-service teacher training, the preparation of preservice teachers, working with families, developing community rehabilitation training programs, and implementing evidence-based practices. Special education in China today is at a good place but it has quite a way from the ideal situation.
Hamid Beladi and Subarna K. Samanta
This article analyses the welfare implications of the customsunions in the presence of multinational corporations for a less thanfully employed small open economy. The traditional…
Abstract
This article analyses the welfare implications of the customs unions in the presence of multinational corporations for a less than fully employed small open economy. The traditional two‐sector model, with a specific factor for the multinational corporation, is employed for this purpose. This article suggests that both trade creations I and II improve the social welfare and employment of the small open economy if the multinational sector is relatively capital‐intensive. However, the welfare and the employment effects of trade diversion I are ambiguous whereas trade diversion II affects employment level negatively. These results are in contrast with the previous studies on the theory of customs unions.
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Chengguo Zong, Zhijian Ji, Junzhi Yu and Haisheng Yu
The purpose of this paper is to study the adaptability of the tracked robot in complex working environment. It proposes an angle-changeable tracked robot with human–robot…
Abstract
Purpose
The purpose of this paper is to study the adaptability of the tracked robot in complex working environment. It proposes an angle-changeable tracked robot with human–robot interaction in unstructured environment. The study aims to present the mechanical structure and human–robot interaction control system of the tracked robot and analyze the static stability of the robot working in three terrains, i.e. rugged terrain, sloped terrain and stairs.
Design/methodology/approach
The paper presents the mechanical structure and human–robot interaction control system of the tracked robot. To prevent the detachment of the tracks during obstacle navigation, a new type of passively adaptive device based on the relationship between the track’s variable angle and the forces is presented. Then three types of rough terrain are chosen to analyze the static stability of the tracked robot, i.e. rugged terrain, sloped terrain and stairs.
Findings
This paper provides the design method of the tracked robot. Owing to its appropriate dimensions, good mass distribution and limited velocity, the tracked robot remains stable on the complex terrains. The experimental results verify the effectiveness of the design method.
Originality/value
The theoretical analysis of this paper provides basic reference for the structural design of tracked robots.
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Abstract
Purpose
After receiving advertising messages, most consumers rarely purchase the advertised products at once, which results in a delay between advertising exposure and its effect. This paper is devoted to exploring the advertising decision and coordination issues for a supply chain system subject to advertising immediate and delayed effects.
Design/methodology/approach
By applying the game theory, the differential game models with delay are constructed for the supply chain to examine the equilibrium advertising efforts, brand goodwill and the optimal profits under the different cooperation situations. A class of transfer payment contracts is designed to achieve the best outcome of the supply chain. Illustrative examples are given to demonstrate the effectiveness of addressed results and provide some managerial perspectives.
Findings
It can be found that the complete cooperation situation can stimulate the advertising investment, drive the product demand and improve the economic profit. Also, a class of transfer payment contracts is designed in this paper, such that the supply chain can perfectly realize the profit maximization, and each member can achieve the Pareto improvement.
Research limitations/implications
This work does not address the random market environment, which can be filled in the future. Furthermore, this paper has been done in a single supply chain structure. It is an interesting future line of research when taking competitive behavior (e.g. competition among manufacturers, retailers or supply chains) into account.
Practical implications
This study will help managers make advertising strategies, advise an optimal cooperation way and design the coordination contracts to ensure the economic development of the supply chain. These obtained conclusions may provide a valuable decision-support for marketing management.
Originality/value
For a supply chain, the most previous literature about dynamic advertising models focused on a single advertising effect-immediate effect. This work explores advertising strategy with double advertising effects and investigates the coordinating power of new transfer payment contracts.