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Article
Publication date: 6 August 2019

Siyun Liu, Wenzeng Zhang and Jie Sun

Underactuated fingers are adapted to generate several grasping modes for different tasks, and coupled fingers and self-adaptive fingers are two important types of them. Aiming to…

Abstract

Purpose

Underactuated fingers are adapted to generate several grasping modes for different tasks, and coupled fingers and self-adaptive fingers are two important types of them. Aiming to expand the application and increase adaptability of robotic hand, this paper aims to propose a novel grasping model, called coupled and indirectly self-adaptive (CISA) grasping model, which is the combination of coupled finger and indirectly self-adaptive finger.

Design/methodology/approach

CISA grasping process includes two stages: first, coupled and then indirectly self-adaptive grasping; thus, it is not only integrated with the good pinching ability of coupled finger but also characterized with the high flexibility of indirectly self-adaptive finger. Furthermore, a CISA hand with linkage-slider, called CISA-LS hand, is designed based on the CISA grasping model, consisting of 1 palm, 5 CISA-LS fingers and 14 degrees of freedom.

Findings

To research the grasping behavior of CISA-LS hand, kinematic analysis, dynamic analysis and force analysis of 2-joint CISA-LS finger are performed. Results of grasping experiments for different objects demonstrate the high reliability and stability of CISA-LS hand.

Originality/value

CISA fingers integrate two grasping modes, coupled grasping and indirectly self-adaptive grasping, into one finger. And a double-linkage-slider mechanism is designed as the switch device.

Details

Industrial Robot: the international journal of robotics research and application, vol. 46 no. 5
Type: Research Article
ISSN: 0143-991X

Keywords

Article
Publication date: 6 July 2015

Mohammad Tabatabaei

– The purpose of this paper is to present a two-loop approach for velocity control of a permanent magnet synchronous motor (PMSM) under mechanical uncertainties.

Abstract

Purpose

The purpose of this paper is to present a two-loop approach for velocity control of a permanent magnet synchronous motor (PMSM) under mechanical uncertainties.

Design/methodology/approach

The inner loop calculates the two-axis stator reference voltages through a feedback linearization method. The outer loop employs an RST control structure to compute the q-axis stator reference current. To increase the robustness of the proposed method, the RST controller parameters are adapted through a fractional order model reference adaptive system (FO-MRAS). The fractional order gradient and Lyapunov methods are utilized as adaptation mechanisms.

Findings

The effect of the fractional order derivative in the load disturbance rejection, transient response speed and the robustness is verified through computer simulations. The simulation results show the effectiveness of the proposed method against the external torque and mechanical parameters uncertainties.

Originality/value

The proposed FO-MRAS based on Lyapunov adaptation mechanism is proposed for the first time. Moreover, application of the FO-MRAS for velocity control of PMSM is presented for the first time.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 34 no. 4
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 1 November 2001

Wayne H. Bovey and Andrew Hede

Observes that the published literature on resistance to organisational change has focused more on organisational issues rather than individual psychological factors. The present…

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Abstract

Observes that the published literature on resistance to organisational change has focused more on organisational issues rather than individual psychological factors. The present study investigated the role of both adaptive and maladaptive defence mechanisms in individual resistance. Surveys were conducted in nine organisations undergoing major change and responses were obtained from 615 employees. The results indicate that five maladaptive defence mechanisms are positively correlated with behavioural intention to resist change, namely, projection, acting out, isolation of affect, dissociation and denial. The adaptive defence mechanism of humour was found to be negatively correlated with resistance intention. Identifies two intervention strategies which can be used by management to address the effects of defence mechanisms on resistance during periods of change in organisations.

Details

Journal of Managerial Psychology, vol. 16 no. 7
Type: Research Article
ISSN: 0268-3946

Keywords

Article
Publication date: 20 September 2021

Yu Lu, Pengpeng Ye, Ming-Zhe Dai, Jin Wu and Chengxi Zhang

This paper aims to address the spacecraft attitude regulation problem in the presence of extrinsic disturbances and actuator faults.

Abstract

Purpose

This paper aims to address the spacecraft attitude regulation problem in the presence of extrinsic disturbances and actuator faults.

Design/methodology/approach

Based on adaptive backstepping design technique, a new concise adaptive dual-mode control scheme is proposed, which can either use the fault information detected by fault diagnosis mechanisms or switch to the fault-unknown mode when the fault diagnosis information is non-existent for control signal generation. These two modes share an adaptive mechanism that reduces the complexity of the algorithm.

Findings

The new fault-tolerant attitude control algorithm can accommodate both modes with and without fault diagnosis mechanisms.

Originality/value

The proposed algorithm in this paper can be applied to both cases when the attitude control system is equipped with or without fault diagnosis capability. This also enhances the robustness of attitude control algorithm. This study performs numerical simulations and verifies that the algorithm could effectively adapt to both modes.

Details

Aircraft Engineering and Aerospace Technology, vol. 94 no. 2
Type: Research Article
ISSN: 1748-8842

Keywords

Article
Publication date: 14 October 2013

Dalibor Petković, Nenad D. Pavlović, Shahaboddin Shamshirband and Nor Badrul Anuar

Passively compliant underactuated mechanisms are one way to obtain the gripper which could accommodate to any irregular and sensitive grasping object. The purpose of the…

1910

Abstract

Purpose

Passively compliant underactuated mechanisms are one way to obtain the gripper which could accommodate to any irregular and sensitive grasping object. The purpose of the underactuation is to use less active inputs than the number of degrees of freedom of the gripper mechanism to drive the open and close motion of the gripper. Another purpose of underaction is to reduce the number of control variables.

Design/methodology/approach

The underactuation can morph shapes of the gripper to accommodate different objects. As a result, the underactuated grippers require less complex control algorithms. The fully compliant mechanism has multiple degrees of freedom and can be considered as an underactuated mechanism.

Findings

This paper presents a new design of the adaptive underactuated compliant gripper with distributed compliance. The optimal topology of the gripper structure was obtained by optimality criteria method using mathematical programming technique. Afterwards, the obtained model was improved by iterative finite element optimization procedure. The gripper was constructed entirely of silicon rubber.

Originality/value

The main points of this paper are the explanation of the development and production of the new compliant gripper structure.

Details

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

Keywords

Article
Publication date: 26 July 2013

Brenton K. Wilburn, Mario G. Perhinschi, Hever Moncayo, Ondrej Karas and Jennifer N. Wilburn

The purpose of this paper is to analyze and compare the performance of several different UAV trajectory tracking algorithms in normal and abnormal flight conditions to investigate…

Abstract

Purpose

The purpose of this paper is to analyze and compare the performance of several different UAV trajectory tracking algorithms in normal and abnormal flight conditions to investigate the fault‐tolerant capabilities of a novel immunity‐based adaptive mechanism.

Design/methodology/approach

The evaluation of these algorithms is performed using the West Virginia University (WVU) UAV simulation environment. Three types of fixed‐parameter algorithms are considered as well as their adaptive versions obtained by adding an immunity‐based mechanism. The types of control laws investigated are: position proportional, integral, and derivative control, outer‐loop nonlinear dynamic inversion (NLDI), and extended NLDI. Actuator failures on the three channels and increased turbulence conditions are considered for several different flight paths. Specific and global performance metrics are defined based on trajectory tracking errors and control surface activity.

Findings

The performance of all of the adaptive controllers proves to be better than their fixed parameter counterparts during the presence of a failure in all cases considered.

Research limitations/implications

The immunity inspired adaptation mechanism has promising potential to enhance the fault‐tolerant capabilities of autonomous flight control algorithms and the extension of its use at all levels within the control laws considered and in conjunction with other control architectures is worth investigating.

Practical implications

The WVU UAV simulation environment has been proved to be a valuable tool for autonomous flight algorithm development, testing, and evaluation in normal and abnormal flight conditions.

Originality/value

A novel adaptation mechanism is investigated for UAV control algorithms with fault‐tolerant capabilities. The issue of fault tolerance of UAV control laws has only been addressed in a limited manner in the literature, although it becomes critical in the context of imminent integration of UAVs within the commercial airspace.

Details

International Journal of Intelligent Unmanned Systems, vol. 1 no. 3
Type: Research Article
ISSN: 2049-6427

Keywords

Article
Publication date: 28 June 2021

Dimitrios Anastasiou and Stelios Giannoulakis

This study investigates which expectation formation mechanism governs Eurozone firms regarding their expectations on external finance availability.

Abstract

Purpose

This study investigates which expectation formation mechanism governs Eurozone firms regarding their expectations on external finance availability.

Design/methodology/approach

In this study, we link consecutive surveys from the Survey on the Access to Finance of Enterprises to bring new evidence on how non-financial corporations shape their expectations on external finance availability.

Findings

In line with the past literature, we demonstrate that the data reject the Rational Expectations hypothesis, and we find evidence in favor of the Adaptive Expectation mechanism.

Originality/value

This is the first study studying firms' expectations of external finance availability, implementing survey data of firms' expectations from the SAFE database on a country level. The formation of firm expectations is vital in directing policymakers in designing appropriate monetary policies, as both the employment and inflation targets of central banks around the world are highly dependent on the firm-level decision process.

Details

Journal of Economic Studies, vol. 49 no. 5
Type: Research Article
ISSN: 0144-3585

Keywords

Book part
Publication date: 4 October 2019

Stephan Manning

This chapter examines key drivers of variation in adaptive capacity of project network organizations (PNOs). PNOs are defined as strategically coordinated sets of longer-term, yet…

Abstract

This chapter examines key drivers of variation in adaptive capacity of project network organizations (PNOs). PNOs are defined as strategically coordinated sets of longer-term, yet project-based relationships, which provide for both stability and change in volatile project businesses. While prior research has emphasized the adaptive role of flexible structures and agency, the author focuses on the role of project variety and contextual embedding and disembedding in building adaptive capacity. Comparing two PNOs in TV movie production, the author argues that differences in adaptive capacity are a function of inter-context connectivity, that is, the level of task and team linkages among diverse project contexts, and the degree to which network ties and relational practices have “dual quality” in being valuable both within and beyond specific project contexts. Findings have important implications for project, network, and organization research.

Details

Managing Inter-organizational Collaborations: Process Views
Type: Book
ISBN: 978-1-78756-592-0

Keywords

Article
Publication date: 1 May 2002

Kwong‐Sak Leung, Jian‐Yong Sun and Zong‐Ben Xu

In this paper, a set of safe adaptive genetic algorithms (sGAs) is proposed based on the Splicing/Decomposable encoding scheme and the efficient speed‐up strategies developed by…

Abstract

In this paper, a set of safe adaptive genetic algorithms (sGAs) is proposed based on the Splicing/Decomposable encoding scheme and the efficient speed‐up strategies developed by Xu et al.. The proposed algorithms implement the self‐adaptation of the problem representation, selection and recombination operators at the levels of population, individual and component which commendably balance the conflicts between “reliability” and “efficiency”, as well as “exploitation” and “exploration” existed in the evolutionary algorithms. It is shown that the algorithms converge to the optimum solution in probability one. The proposed sGAs are experimentally compared with the classical genetic algorithm (CGA), non‐uniform genetic algorithm (nGA) proposed by Michalewicz, forking genetic algorithm (FGA) proposed by Tsutsui et al. and the classical evolution programming (CEP). The experiments indicate that the new algorithms perform much more efficiently than CGA and FGA do, comparable with the real‐coded GAs — nGA and CEP. All the algorithms are further evaluated through an application to a difficult real‐life application problem: the inverse problem of fractal encoding related to fractal image compression technique. The results for the sGA is better than those of CGA and FGA, and has the same, sometimes better performance compared to those of nGA and CEP.

Details

Engineering Computations, vol. 19 no. 3
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 18 November 2013

Dalibor Petkovic´ and Nenad D. Pavlovic´

– The paper aims to discuss a new design methodology for multi-fingered robotic grippers.

Abstract

Purpose

The paper aims to discuss a new design methodology for multi-fingered robotic grippers.

Design/methodology/approach

Optimization of the compliant mechanism with underactuation.

Findings

A new robotic gripper principle without active control.

Originality/value

Design of multi-fingered robotic gripper as a monolithic structure without joints.

Details

Multidiscipline Modeling in Materials and Structures, vol. 9 no. 4
Type: Research Article
ISSN: 1573-6105

Keywords

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