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Article
Publication date: 27 September 2021

Yongyao Li, Ming Cong, Dong Liu, Yu Du, Minjie Wu and Clarence W. de Silva

Rigid robotic hands are generally fast, precise and capable of exerting large forces, whereas soft robotic hands are compliant, safe and adaptive to complex environments…

Abstract

Purpose

Rigid robotic hands are generally fast, precise and capable of exerting large forces, whereas soft robotic hands are compliant, safe and adaptive to complex environments. It is valuable and challenging to develop soft-rigid robotic hands that have both types of capabilities. The paper aims to address the challenge through developing a paradigm to achieve the behaviors of soft and rigid robotic hands adaptively.

Design/methodology/approach

The design principle of a two-joint finger is proposed. A kinematic model and a stiffness enhancement method are proposed and discussed. The manufacturing process for the soft-rigid finger is presented. Experiments are carried out to validate the accuracy of the kinematic model and evaluate the performance of the flexible body of the finger. Finally, a robotic hand composed of two soft-rigid fingers is fabricated to demonstrate its grasping capacities.

Findings

The kinematic model can capture the desired distal deflection and comprehensive shape accurately. The stiffness enhancement method guarantees stable grasp of the robotic hand, without sacrificing its flexibility and adaptability. The robotic hand is lightweight and practical. It can exhibit different grasping capacities.

Practical implications

It can be applied in the field of industrial grasping, where the objects are varied in materials and geometry. The hand’s inherent characteristic removes the need to detect and react to slight variations in surface geometry and makes the control strategies simple.

Originality/value

This work proposes a novel robotic hand. It possesses three distinct characteristics, i.e. high compliance, exhibiting discrete or continuous kinematics adaptively, lightweight and practical structures.

Details

Industrial Robot: the international journal of robotics research and application, vol. 48 no. 6
Type: Research Article
ISSN: 0143-991X

Keywords

Article
Publication date: 17 August 2015

Wei Wang, Shilin Wu, Peihua Zhu and Xuepeng Li

The paper aims to present a new thought for design of a thrown robot based on flexible structures. The aim of the design is to reduce the weight and improve the…

Abstract

Purpose

The paper aims to present a new thought for design of a thrown robot based on flexible structures. The aim of the design is to reduce the weight and improve the anti-impact capability for mini thrown robot.

Design/methodology/approach

A mass-spring wheeled robot model is proposed and an impact analysis is given in this paper. Some principia were derived for configuration design and material choice to get a light and robust thrown reconnaissance robot. Based on the theoretical analysis, flexible elements like flexure hinges or rubber shell were utilized to build two generation of robots that both showed excellent performances of anti-impact ability.

Findings

A second-generation thrown robot (2,050 g) was developed, which could survive dropping from the height of 6 m more than 10 times without apparent damage.

Originality/value

The method based on the flexible structure provides the thrown robot with high survivability from impact, as well as light weight. It can be used in the design of the mini thrown reconnaissance robot at low cost.

Details

Industrial Robot: An International Journal, vol. 42 no. 5
Type: Research Article
ISSN: 0143-991X

Keywords

Article
Publication date: 5 December 2018

Yu Liu, Jie Hao, Zhihua Sha, Fujian Ma, Chong Su and Shengfang Zhang

Aiming at the unbalancing problem of the neutral equilibrium characteristic for balance hoist in the loading process, the purpose of this paper is to establish a dynamic…

Abstract

Purpose

Aiming at the unbalancing problem of the neutral equilibrium characteristic for balance hoist in the loading process, the purpose of this paper is to establish a dynamic equation for multi-body using the Lagrange method. It is not difficult to find that the deformation of the boom system has a great influence on the stability of the whole system, through the simulation analysis of the multi-rigid-body system model.

Design/methodology/approach

Aiming at the unbalancing problem of the neutral equilibrium characteristic for balance hoist in the loading process, the dynamic equation for multi-body is established by Lagrange method. It is not difficult to find that the deformation of the boom system has a great influence on the stability of the whole system, through the simulation analysis of the multi-rigid-body system model.

Findings

Result shows that different weights have a great influence on the force deformation and vibration of the boom system of balance hoist. With the increase in lifting weight, the force and deformation of the boom system increase; lead to balance hoist unique with characteristics of indifferent equilibrium, proportional amplification, labor-saving operation will be lost, easy to cause the imbalance of balance hoist. Therefore, the appropriate increase in the basic length of the compression bar, reduction in the basic length of the tension rod and the increase stiffness of the boom system can improve the stability of balance hoist, which provides a reference for the optimization and manufacture of the balance hoist structure.

Originality/value

The simulation model was established by analyzing the working principle and the load condition of the balance hoist, and the simulation and dynamic characteristics of three typical working conditions are analyzed by using ADAMS; result shows that different weights have a great influence on the force deformation and vibration of the boom system of balance hoist. With the increase in lifting weight, the force and deformation of a boom system increase, lead to balance hoist unique with characteristics of indifferent equilibrium, proportional amplification, labor-saving operation will be lost, easy to cause the imbalance of balance hoist.

Details

Multidiscipline Modeling in Materials and Structures, vol. 15 no. 2
Type: Research Article
ISSN: 1573-6105

Keywords

Article
Publication date: 5 October 2012

Denis Anders, Stefan Uhlar, Melanie Krüger, Michael Groß and Kerstin Weinberg

Wind turbines are of growing importance for the production of renewable energy. The kinetic energy of the blowing air induces a rotary motion and is thus converted into…

Abstract

Purpose

Wind turbines are of growing importance for the production of renewable energy. The kinetic energy of the blowing air induces a rotary motion and is thus converted into electricity. From the mechanical point of view the complex dynamics of wind turbines become a matter of interest for structural optimization and optimal control in order to improve stability and energy efficiency. The purpose of this paper therefore is to present a mechanical model of a three‐blade wind turbine with a momentum and energy conserving time integration of the system.

Design/methodology/approach

The authors present a mechanical model based upon a rotationless formulation of rigid body dynamics coupled with flexible components. The resulting set of differential‐algebraic equations will be solved by using energy‐consistent time‐stepping schemes. Rigid and orthotropic‐elastic body models of a wind turbine show the robustness and accuracy of these schemes for the relevant problem.

Findings

Numerical studies prove that physically consistent time‐stepping schemes provide reliable results, especially for hybrid wind turbine models.

Originality/value

The application of energy‐consistent methods for time discretization is intended to provide computational robustness and to reduce the computational costs of the dynamical wind turbine systems. The model is aimed to give a first access into the investigation of fluid‐structure interaction for wind turbines.

Article
Publication date: 1 March 2006

Guo‐Ping Cai and Jia‐Zhen Hong

In this paper, a first‐order approximation coupling (FOAC) model is investigated to analyze the dynamics of the hub‐beam system, which is based on the Hamilton theory and…

Abstract

In this paper, a first‐order approximation coupling (FOAC) model is investigated to analyze the dynamics of the hub‐beam system, which is based on the Hamilton theory and the finite element discretization method. The FOAC model for the hub‐beam system considers the second‐order coupling quantity of the axial displacement caused by the transverse displacement of the beam. The dynamic characteristics of the system are studied through numerical simulations under twos cases: the rotary inertia of the hub is much larger than, and is close to, that of the flexible beam. Simulation and comparison studies using both the traditional zeroth‐order approximation coupling (ZOAC) model and the FOAC model shows that when large motion of the system is unknown, possible failure exists by using the ZOAC model, whereas the FOAC model is valid. When the rotary inertia of the hub is much larger than that of the beam, the result using the ZOAC model is similar to that using the FOAC model. But when the rotary inertia of the hub is close to that of the beam, the ZOAC model may lead to a large error, while the FOAC model can still accurately describe the dynamic hub‐beam system.

Details

Multidiscipline Modeling in Materials and Structures, vol. 2 no. 3
Type: Research Article
ISSN: 1573-6105

Keywords

Article
Publication date: 19 June 2017

Zhao Tang, Peng Qi and Jian Dai

This paper aims to introduce a novel design of the biomimetic quadruped robot, including its body structure, three structural modes and respective workspace.

Abstract

Purpose

This paper aims to introduce a novel design of the biomimetic quadruped robot, including its body structure, three structural modes and respective workspace.

Design/methodology/approach

By taking a metamorphic 8-bar linkage as the body of a quadruped robot, the authors propose a reconfigurable walking robot that can imitate three kinds of animals: mammals (e.g. dog), arthropods (e.g. stick insect) and reptiles (e.g. lizard). Furthermore, to analyze the three structural modes of this quadruped robot, the workspace is calculated and studied.

Findings

Based on experimental data analyses, it is revealed that the metamorphic quadruped robot can walk in all its three structural modes and adapt to different terrains.

Research limitations/implications

Because the body of the quadruped robot is deformable and reconfigurable, the location of payload is not considered in the current stage.

Practical implications

The relative positions and postures of legs of the metamorphic robot can be rearranged during its body reconfiguration in such a way to combine all the features of locomotion of the three kinds of animals into one robot. So, the metamorphic quadruped robot is capable of maintaining wider stability margins than conventional rigid-body quadruped robots and conducting operations in different environments, particularly the extreme and restricted occasions due to the changeable and adaptable trunk.

Originality/value

The main contribution is the development of a reconfigurable biomimetic quadruped robot, which uses the metamorphic 8-bar linkage. This robot can easily reshape to three different structural modes and mimic the walking patterns of all mammals, arthropods and reptiles.

Details

Industrial Robot: An International Journal, vol. 44 no. 4
Type: Research Article
ISSN: 0143-991X

Keywords

Article
Publication date: 22 January 2020

Jiangtao Xu, Na Luo, Shaojie Liu, Baoshan Zhao, Fang Qi, Yinjun Lian and Litong Wang

The purpose of this paper is to design a component synthesis method to suppress the vibration of the flexible spacecraft, which has the constant amplitude force/moment actuator.

Abstract

Purpose

The purpose of this paper is to design a component synthesis method to suppress the vibration of the flexible spacecraft, which has the constant amplitude force/moment actuator.

Design/methodology/approach

The authors proposed a method to construct constant amplitude of time delay and composite coefficient sequences based on the principles of the component synthesis vibration suppression (CSVS). The associated design strategy of the CSVS torque control is also developed. The dynamic model consisting of a single axis rotating rigid central body and a fixed flexibility panel is used to validate the proposed method. Constraint modal and free modal method are both tested to analyse the natural frequencies of the panel and dynamic properties of rigid–flexible decoupling system, under the conditions of known and unknown frequencies. The feasibility of constructing CSVS control force based on the constraint modal frequency is also analysed.

Findings

The proposed method can suppress multistage vibration and has arbitrary order robustness for each order frequencies simultaneously. Simulation results show that only the duration time of the actuator has to be set for the proposed method, reasonable vibration suppression effect can be achieved.

Practical implications

The method can be used in spacecraft, especially flexible spacecraft to suppress the vibration; the approach is convenient for engineering application and can be easily designed.

Originality/value

The authors proposed a method to construct constant amplitude of time delay and composite coefficient sequences based on the principles of the CSVS.

Details

Aircraft Engineering and Aerospace Technology, vol. 92 no. 2
Type: Research Article
ISSN: 1748-8842

Keywords

Article
Publication date: 1 March 1986

Ronald L. Huston

This paper presents algorithms for computing the angular velocities of the bodies of a multibody system. A multibody system is any collection of connected bodies. The…

Abstract

This paper presents algorithms for computing the angular velocities of the bodies of a multibody system. A multibody system is any collection of connected bodies. The focus is upon multibody systems consisting of spherically pinned rigid bodies which do not form closed loops. Simple formulae are presented for computing the angular velocities. It is shown that once the angular velocities are known the entire kinematical description and hence, the dynamics of the system, may be developed routinely and in automated fashion. Extension to more general multibody systems follows without conceptual change in the procedures.

Details

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

Article
Publication date: 9 March 2015

Lidui Wei, Haijun Wei, Shulin Duan and Yu Zhang

The purpose of this paper is to develop a good calculation model to accurately predict the lubrication characteristic of main bearings of diesel engine and improve the…

Abstract

Purpose

The purpose of this paper is to develop a good calculation model to accurately predict the lubrication characteristic of main bearings of diesel engine and improve the service life.

Design/methodology/approach

Based on the coupling of the whole flexible engine block and the flexible crankshaft reduced by the Component Mode Synthesis (CMS) method, considering mass-conserving boundary conditions, the average flow model equation and Greenwood/Tripp asperity contact theory, an elastohydrodynamic (EHD)-mixed lubrication model of the main bearings for the diesel engine is developed and researched with the finite volume method and the finite element method.

Findings

Obviously, the mixed lubrication of bearings is normal, while full hydrodynamic lubrication is transient. The results show that under the whole flexible block model, maximum oil film pressure, maximum asperity contact pressure and radial shell deformation decrease, while minimum oil film thickness increases. Oil flow over edge decreases, and so does friction loss. Therefore, coordination deformation ability of whole engine block is favorable to mean load. In the whole block model, friction contact happens on both upper shell and lower shell positions. In addition, average oil film fill ratio at the key position becomes smaller in the whole engine block model, and consequently increases the chances of cavitations erosion more. So, wearing resistance of both upper and lower shells and anti-cavitations erosion ability must be enhanced simultaneously.

Originality/value

Based on the coupling of the whole flexible engine block and the flexible crankshaft reduced by the CMS method, considering mass-conserving boundary conditions, the average flow model equation and Greenwood/Tripp asperity contact theory, an EHD-mixed lubrication model of the main bearings for the diesel engine is built, which can predict the lubrication of journal bearings more accurately.

Details

Industrial Lubrication and Tribology, vol. 67 no. 2
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 2 February 2015

M. Grujicic, V. Chenna, R. Yavari, R. Galgalikar, J.S. Snipes and S. Ramaswami

To make wind energy (one of the alternative-energy production technologies) economical, wind-turbines (convertors of wind energy into electrical energy) are required to…

Abstract

Purpose

To make wind energy (one of the alternative-energy production technologies) economical, wind-turbines (convertors of wind energy into electrical energy) are required to operate, with only regular maintenance, for at least 20 years. However, some key wind-turbine components (especially the gear-box) often require significant repair or replacement after only three to five years in service. This causes an increase in both the wind-energy cost and the cost of ownership of the wind turbine. The paper aims to discuss these issues.

Design/methodology/approach

To overcome this problem, root causes of the gear-box premature failure are currently being investigated using mainly laboratory and field-test experimental approaches. As demonstrated in many industrial sectors (e.g. automotive, aerospace, etc.) advanced computational engineering methods and tools cannot only complement these experimental approaches but also provide additional insight into the problem at hand (and do so with a substantially shorter turn-around time). The present work demonstrates the use of a multi-length-scale computational approach which couples large-scale wind/rotor interactions with a gear-box dynamic response, enabling accurate determination of kinematics and kinetics within the gear-box bearings (the components most often responsible for the gear-box premature failure) and ultimately the structural response (including damage and failure) of the roller-bearing components (e.g. inner raceways).

Findings

It has been demonstrated that through the application of this approach, one can predict the expected life of the most failure-prone horizontal axis wind turbine gear-box bearing elements.

Originality/value

To the authors’ knowledge, the present work is the first multi-length-scale study of bearing failure in wind-turbines.

Details

International Journal of Structural Integrity, vol. 6 no. 1
Type: Research Article
ISSN: 1757-9864

Keywords

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