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Article
Publication date: 14 September 2011

P. Zak, J. Lelito, J. Suchy, W. Krajewski, K. Haberl and P. Schumacher

The aim of this paper was to determine fitting parameters in grain density of the magnesium primary phase function in AZ91/SiC composite heterogeneous nucleation model…

Abstract

The aim of this paper was to determine fitting parameters in grain density of the magnesium primary phase function in AZ91/SiC composite heterogeneous nucleation model. Nucleation models have parameters, which exact values are usually not known and sometimes even their physical meaning is under discussion. Those parameters can be obtained after statistical analyze of the experimental data. Specimens of fourteen different composites were prepared. The matrix of the composite was AZ91 and the reinforcement was SiC particles. The specimens differs in SiC particles size (10 μm, 40 μm, 76 μm) and content (0 wt.%, 0.1 wt.%, 0.5 wt.%, 2 wt.%, 3.5 wt.%). They were taken from the region near to the thermocouple, to analyze the undercooling for different composites and its influence on the grain size. The specimens were polished and etched. The mean grain size for each specimen was measured. Specific undercooling for each composite was found from characteristic points on cooling rate curve. Microstructure and thermal analyze gave set of values that connect SiC particles content, their size and alloy undercooling with grain size. Those values were used to approximate nucleation model adjustment parameters. Obtained model can be very useful in modelling composites microstructure.

Details

World Journal of Engineering, vol. 8 no. 3
Type: Research Article
ISSN: 1708-5284

Keywords

Article
Publication date: 3 October 2022

Wei Zhao, Juliang Xiao, Sijiang Liu, Saixiong Dou and Haitao Liu

In customized production such as plate workpiece grinding, because of the diversity of the workpiece shapes and the positional/orientational clamping errors, great efforts…

Abstract

Purpose

In customized production such as plate workpiece grinding, because of the diversity of the workpiece shapes and the positional/orientational clamping errors, great efforts are taken to repeatedly calibrate and program the robots. To change this situation, the purpose of this study is to propose a method of robotic direct grinding for unknown workpiece contour based on adaptive constant force control and human–robot collaboration.

Design/methodology/approach

First, an adaptive constant force controller based on stiffness estimation is proposed, which can distinguish the contact of the human hand and the unknown workpiece contour. Second, a normal vector search algorithm is developed to calculate the normal vector of the unknown workpiece contour in real-time. Finally, the force and position are controlled in the calculated normal and tangential directions to realize the direct grinding.

Findings

The method considers the disturbance of the tangential grinding force and the friction, so the robot can track and grind the workpiece contour simultaneously. The experiments prove that the method can ensure the force error and the normal vector calculating error within 0.3 N and 4°. This human–robot collaboration pattern improves the convenience of the grinding process.

Research limitations/implications

The proposed method realizes constant force grinding of unknown workpiece contour in real-time and ensures the grinding consistency. In addition, combined with human–robot collaboration, the method saves the time spent in repeated calibration and programming.

Originality/value

Compared with other related research, this method has better accuracy and anti-disturbance capability of force control and normal vector calculation during the actual grinding process.

Details

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

Keywords

Article
Publication date: 23 August 2015

Lixia Yin, Shunxing Liang and Liyun Zheng

Effects of major factors, such as alloy composition, crystal structure and grain size, on mechanical properties of TiZr based alloys are investigated and summarized in…

Abstract

Effects of major factors, such as alloy composition, crystal structure and grain size, on mechanical properties of TiZr based alloys are investigated and summarized in this work. The microhardness of TC4 alloy obviously increases 15.3% and 17.6% after 30 wt.% and 47 wt.% Zr additions, respectively. Nanoindentation results show that the average nanoindentation hardness of α phase in annealed 30 Zr is approximately 18% higher than that of retained β phase. Tensile test results show that variation in strength of basketweave microstructural 30 Zr alloy with original β grain size from 100 to 203 μm is less than 2%.

Details

World Journal of Engineering, vol. 12 no. 4
Type: Research Article
ISSN: 1708-5284

Keywords

Article
Publication date: 15 August 2016

Guilherme Boulhosa Rodamilans, Emília Villani, Luís Gonzaga Trabasso, Wesley Rodrigues de Oliveira and Ricardo Suterio

This paper aims to propose an evaluation method to compare two different Human–Robot Interaction (HRI) solutions that can be used for on-line programming in an industrial…

Abstract

Purpose

This paper aims to propose an evaluation method to compare two different Human–Robot Interaction (HRI) solutions that can be used for on-line programming in an industrial context: a force guidance system and the traditional teach pendant operation.

Design/methodology/approach

The method defines three evaluation criteria (agility, accuracy and learning) and describes an experimental approach based on the analysis of variance to verify the performance of guidance systems according to these criteria. This method is used in this paper to compare the traditional teach pendant interface with an implementation of a force guidance system based on the use of an external force/torque sensor.

Findings

The application of the proposed method to an off-the-shelf industrial robot shows that the force guidance system has a better performance according to the agility criterion. Both solutions have a similar performance for the accuracy criterion, with a limit of about 2 mm in the achieved position accuracy. Regarding the learning criterion, the authors cannot affirm that any of the methods has an improved agility when the operator repeats the tasks.

Practical implications

This work supports the selection of guidance systems to be used in on-line programming of industrial applications. It shows that the force guidance system is an option potentially faster than the teach pendant when the required positioning accuracy is greater than 2 mm.

Originality/value

The new method proposed in this paper can be applied to a large range of robots, not being limited to commercial available collaborative robots. Furthermore, the method is appropriate to accomplish further investigations in HRI not only to compare programming methods but also to evaluate guidance systems approaches or robot control systems.

Details

Industrial Robot: An International Journal, vol. 43 no. 5
Type: Research Article
ISSN: 0143-991X

Keywords

Article
Publication date: 16 May 2016

Changhong Gao, Dacheng Cong, Xiaochu Liu, Zhidong Yang and Han Tao

The purpose of this paper is to propose a hybrid position/force control scheme using force and vision for docking task of a six degrees of freedom (6-dof) hydraulic…

Abstract

Purpose

The purpose of this paper is to propose a hybrid position/force control scheme using force and vision for docking task of a six degrees of freedom (6-dof) hydraulic parallel manipulator (HPM).

Design/methodology/approach

The vision system consisted of a charge-coupled device (CCD) camera, and a laser distance sensor is used to provide globe relative position information. Also, a force plate is used to measure local contact forces. The proposed controller has an inner/outer loop structure. The inner loop takes charge of tracking command pose signals from outer loop as accurate as possible, while the outer loop generates the desired tracking trajectory according to force and vision feedback information to guarantee compliant docking. Several experiments have been performed to validate the performance of the proposed control scheme.

Findings

Experiment results show that the system has good performance of relative position tracking and compliant contact. In whole docking dynamic experiment, the amplitudes of contact forces are well controlled within 300 N, which can meet perfectly the requirement of the amplitude being not more than 1,000 N.

Originality/value

A hybrid position/force control scheme using force and vision is proposed to make a 6-dof HPM dock with a moving target object compliantly.

Details

Industrial Robot: An International Journal, vol. 43 no. 3
Type: Research Article
ISSN: 0143-991X

Keywords

Article
Publication date: 16 October 2018

Hongtai Cheng and Hongfei Jiang

Delta robot is a parallel robot specifically designed for high-speed pick and place tasks. However, sometimes they are asked to perform additional assembling and squeezing…

Abstract

Purpose

Delta robot is a parallel robot specifically designed for high-speed pick and place tasks. However, sometimes they are asked to perform additional assembling and squeezing actions, which is beyond the capability of position-controlled Delta robots. Force sensors may be expensive and add mass to the system. Therefore, the purpose of this paper is to study sensorless force control of Delta robots using limited access interface.

Design/methodology/approach

Static force analysis is performed to establish a relation between joint torques and external forces. The joint torques are observed from signals provided by motor drivers. A distributed mass model is proposed to compensate the gravity of upper arms and forearms. To minimize the effect of backlash and nonlinear frictions brought by gearboxes, model parameters are calibrated in two separated modes: “LIFTING” and “LOWERING”. Finally, a hybrid force estimation model is built to deal with both cases simultaneously. Surrogate model-based force control law is proposed to increase the force control loop rate and handle the force control problem for discrete position-controlled Delta robots.

Findings

The results show that the force estimation model is effective and mode separation can significantly improve the accuracy. The force control laws indeed stabilize the robot in desired states.

Originality/value

The proposed solution is based on position-controlled commercial Delta robot and requires no additional force sensor. It is able to extend Delta robots’ capability and meet requirements of emerging complex tasks.

Details

Industrial Robot: An International Journal, vol. 45 no. 5
Type: Research Article
ISSN: 0143-991X

Keywords

Article
Publication date: 19 November 2019

Pengcheng Wang, Dengfeng Zhang and Baochun Lu

This paper aims to address the collision problem between robot and the external environment (including human) in an unstructured situation. A new collision detection and…

Abstract

Purpose

This paper aims to address the collision problem between robot and the external environment (including human) in an unstructured situation. A new collision detection and torque optimization control method is proposed.

Design/methodology/approach

Firstly, when the collision appears, a second-order Taylor observer is proposed to estimate the residual value. Secondly, the band-pass filter is used to reduce the high-frequency torque modeling dynamic uncertainty. With the estimate information and the torque value, a variable impedance control approach is then synthesized to guarantee that the collision is avoided or the collision will be terminated with different contact models and positions. However, in terms of adaptive linear force error, the variation of the thickness of the boundary layer is controlled by the new proximity function.

Findings

Finally, the experimental results show the better performance of the proposed control method, realizing the force control during the collision process.

Originality/value

Origin approach and origin experiment.

Details

Industrial Robot: the international journal of robotics research and application, vol. 47 no. 6
Type: Research Article
ISSN: 0143-991X

Keywords

Article
Publication date: 22 July 2019

Liming Gao, Jianjun Yuan and Yingjie Qian

The purpose of this paper is to design a practical direct teaching method for the industrial robot with large friction resistance and gravity torque but without expensive…

Abstract

Purpose

The purpose of this paper is to design a practical direct teaching method for the industrial robot with large friction resistance and gravity torque but without expensive force/torque sensor, where the gravity torque is just a function of joints position, whereas the friction is closely associated with joint velocity, temperature and load.

Design/methodology/approach

In the teaching method, the output torque of joint motor is controlled through current to compensate gravity torque completely and friction resistance incompletely. Three variables closely associated with friction are investigated separately by experiment and theoretical analysis, and then a comprehensive friction model which is used to calculate the required compensated friction torque is proposed. Finally, a SIASUN 7 degrees of freedom robot was used to verify the model and the method.

Findings

Experimental results demonstrated that the teaching method enables an operator to teach the robot in joint space by applying small force and torque on either end-effector or its body. The friction investigation suggests that the velocity and temperature have a strong nonlinear influence on viscous friction, whereas load torque significantly influences the Coulomb friction linearly and causes a slight Stribeck effect.

Originality/value

The main contribution includes the following: a practical joint space direct teaching method for a common industrial robot is developed, and a friction model capturing velocity, temperature and load for robot joints equipped with commercialized motors and harmonic drives is proposed.

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: 28 January 2020

Hassanudin Mohd Thas Thaker, K. Chandra Sakaran, N. Madhavan Nanairan, Mohamed Asmy Mohd Thas Thaker and Hafezali Iqbal Hussain

The growth of Islamic banking seems to be tremendous and significant in the context of Malaysia. Moreover, together with Muslim loyalty towards Islamic banking…

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Abstract

Purpose

The growth of Islamic banking seems to be tremendous and significant in the context of Malaysia. Moreover, together with Muslim loyalty towards Islamic banking, non-Muslims are also showing positive acceptance towards Islamic banking in Malaysia. Thus, this paper aims to examine the drivers of loyalty among non-Muslim in their adoption of Islamic banking products in Malaysia.

Design/methodology/approach

The primary data are collected from the survey administered to non-Muslim clients in Kuala Lumpur and Selangor. The total number of respondents involved are n = 300. The analysis of data is conducted by using a partial least square analysis.

Findings

This study documented that loyalty among non-Muslim Islamic banking customers in Malaysia was mainly driven by convenience, product pricing, reliability and responsiveness, operational risk and security and value added services. Only one variable was found to be insignificant, which was accessibility.

Practical implications

The results from this research is expected to provide important inputs on the critical factors for consideration by Islamic banks in maintaining further loyalty among their non-Muslim customers, thus enhancing the development of Islamic banking in Malaysia.

Originality/value

This paper provides further literature evidence on the factors contributes to loyalty by considering non-Muslims patronization of Islamic banking in Malaysia.

Details

International Journal of Islamic and Middle Eastern Finance and Management, vol. 13 no. 2
Type: Research Article
ISSN: 1753-8394

Keywords

Article
Publication date: 12 February 2021

Shijie Dai, Shining Li, Wenbin Ji, Zhenlin Sun and Yufeng Zhao

This study aims to realize the constant force grinding of automobile wheel hub.

Abstract

Purpose

This study aims to realize the constant force grinding of automobile wheel hub.

Design/methodology/approach

A force control strategy of backstepping + proportion integration differentiation (PID) is proposed. The grinding end effector is installed on the flange of the robot. The robot controls the position and posture of the grinding end actuator and the grinding end actuator controls the grinding force output. First, the modeling and analysis of the grinding end effector are carried out, and then the backstepping + PID method is adopted to control the grinding end effector to track the expected grinding force. Finally, the feasibility of the proposed method is verified by simulation and experiment.

Findings

The simulation and experimental results show that the backstepping + PID strategy can track the expected force quickly, and improve the dynamic response performance of the system and the quality of grinding and polishing of automobile wheel hub.

Research limitations/implications

The mathematical model is based on the pneumatic system and ideal gas, and ignores the influence of friction in the working process of the cylinder, so the mathematical model proposed in this study has certain limitations. A new control strategy is proposed, which is not only used to control the grinding force of automobile wheels, but also promotes the development of industrial control.

Social implications

The automatic constant force grinding of automobile wheel hub is realized, and the manpower is liberated.

Originality/value

First, the modeling and analysis of the grinding end effector are carried out, and then the backstepping + PID method is adopted to control the grinding end effector to track the expected grinding force. The nonlinear model of the system is controlled by backstepping method, and in the process, the linear system composed of errors is obtained, and then the linear system is controlled by PID to realize the combination of backstepping and PID control.

Details

Industrial Robot: the international journal of robotics research and application, vol. 49 no. 1
Type: Research Article
ISSN: 0143-991X

Keywords

1 – 10 of 75