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Article
Publication date: 1 February 1995

A.J. Burkhardt

This paper presents the results of research into the process of testing controlled impedance circuit boards. It aims to provide a general introduction to the subject of…

Abstract

This paper presents the results of research into the process of testing controlled impedance circuit boards. It aims to provide a general introduction to the subject of controlled impedance circuit board production for manufacturers wishing to make this type of board in the future and offers constructive suggestions for those who may want to improve on their current process. Consequently, in addition to describing test issues there are references to some of the other main subject areas that require attention when the production of high quality controlled impedance circuit boards is to be considered, namely design, materials and fabrication. The content of this paper is based on production trials that were conducted by MEPD Met‐Etch (Selkirk) Ltd at their manufacturing facilities in Scotland as part of a UK Ministry of Defence research contract. The results of this research were included in a report for the UK Defence Research Agency (Electronics Division) and subsequently were also detailed in an individual ‘Guidelines for Designers’ document. This document has since been separately submitted to ECL 19 with a view towards incorporation into the CECC 23000 Approval System. In order to verify the test results, separate comparison measurements were also conducted by other circuit board manufacturers using a range of suitable test instrumentation. There is a growing requirement in the printed circuit board industry for a simple means of testing controlled impedance boards. This paper promotes the use of computer‐controlled test instrumentation so that accurate and repeatable measurements can be made by production staff in a manufacturing environment. If this is achieved, it should be possible to close the quality loop on controlled impedance circuit board production using normal statistical process control techniques.

Details

Circuit World, vol. 21 no. 2
Type: Research Article
ISSN: 0305-6120

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Article
Publication date: 28 August 2007

Antonio M. Lopes and Fernando G. Almeida

This paper seeks to present an acceleration‐based force‐impedance controller, applied to a six‐dof parallel mini‐manipulator: the robotic controlled impedance device (RCID).

Abstract

Purpose

This paper seeks to present an acceleration‐based force‐impedance controller, applied to a six‐dof parallel mini‐manipulator: the robotic controlled impedance device (RCID).

Design/methodology/approach

The proposed control strategy involves three cascade controllers: an inner acceleration controller, built as a set of six single input/single output acceleration controllers (one per manipulator axis), an impedance task‐space controller, and an outer force controller.

Findings

The control strategy enables two kinds of manipulator behaviour: force‐limited impedance control and position‐limited force control. The type of behaviour depends only on the chosen manipulator trajectories.

Practical implications

The RCID may be used as a force‐impedance controlled auxiliary device, coupled in series with a position‐controlled commercial industrial robot. The two manipulators combined behave as a single manipulator, having the impedance and force control performance of the RCID, as well as the workspace and trajectory tracking performance of the industrial manipulator. The industrial manipulator should perform free space motion trajectory tracking, the RCID being kept in a “home” position, preserving its small workspace for impedance and force control.

Originality/value

A robust control strategy that enables good performance, while the robot executes tasks that involve interaction with the environment, is being proposed. Experimental results on a force‐impedance controlled six‐dof parallel mini‐manipulator are presented.

Details

Industrial Robot: An International Journal, vol. 34 no. 5
Type: Research Article
ISSN: 0143-991X

Keywords

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Article
Publication date: 15 August 2016

Ali Leylavi Shoushtari, Paolo Dario and Stefano Mazzoleni

Interaction plays a significant role in robotics and it is considered in all levels of hardware and software control design. Several models have been introduced and…

Abstract

Purpose

Interaction plays a significant role in robotics and it is considered in all levels of hardware and software control design. Several models have been introduced and developed for controlling robotic interaction. This study aims to address and analyze the state-of-the-art on robotic interaction control by which it is revealed that both practical and theoretical issues have to be faced when designing a controller.

Design/methodology/approach

In this review, a critical analysis of the control algorithms developed for robotic interaction tasks is presented. A hierarchical classification of distributed control levels from general aspects to specific control algorithms is also illustrated. Hence, two main control paradigms are discussed together with control approaches and architectures. The challenges of each control approach are discussed and the relevant solutions are presented.

Findings

This review presents an evolvement trend of interaction control theories and technologies over time. In addition, it highlights the pros and cons of each control approaches with addressing how the flaws of one control approach were compensated by emerging another control methods.

Originality/value

This review provides the robotic controller designers to select the right architecture and accordingly design the appropriate control algorithm for any given interactive task and with respect to the technology implemented in robotic manipulator.

Details

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

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Article
Publication date: 7 August 2017

Ningbo Yu and Wulin Zou

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…

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.

Details

Assembly Automation, vol. 37 no. 3
Type: Research Article
ISSN: 0144-5154

Keywords

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Article
Publication date: 7 February 2020

Hongli Cao, Ye He, Xiaoan Chen and Xue Zhao

The purpose of this paper is to take transient contact force response, overshoots and steady-state force tracking error problems into account to form an excellent force controller.

Abstract

Purpose

The purpose of this paper is to take transient contact force response, overshoots and steady-state force tracking error problems into account to form an excellent force controller.

Design/methodology/approach

The basic impedance function with a pre-PID tuner is designed to improve the force response. A dynamic adaptive adjustment function that combines the advantages of hybrid impedance and adaptive hybrid impedance control is presented to achieve both force overshoots suppressing and tracking ability.

Findings

The introduced pre-PID tuner impedance function can achieve more than the pure impedance function in aspects of converging to the desired value and reducing the force overshoots. The performance of force overshoots suppression and force tracking error are maintained by introducing the dynamic adaptive sigma adjustment function. The simulation and experimental results both show the achieved control performance by comparing with the previous control methods.

Practical implications

The implementation of the controller is easy and convenient in practical manufacture scenes that require force control using industrial robots.

Originality/value

A superior robot controller adapting to a variety of complex tasks owing to the following characteristics: maintenance of high-accuracy position tracking capability in free-space (basic capabilities of modern industrial robots); maintenance of high speed, stability and smooth contact performance in collision stage; and presentation of high-precision force tracking capability in steady contact.

Details

Industrial Robot: the international journal of robotics research and application, vol. 47 no. 2
Type: Research Article
ISSN: 0143-991X

Keywords

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Article
Publication date: 8 June 2021

Guojun Zhang, Fenglei Ni, Hong Liu, Zainan Jiang, Guocai Yang and Chongyang Li

The purpose of this paper is to transfer the impedance regulation of manual belt grinding to robot belt grinding control.

Abstract

Purpose

The purpose of this paper is to transfer the impedance regulation of manual belt grinding to robot belt grinding control.

Design/methodology/approach

This paper presents a novel methodology for transmitting human impedance regulation skills to robot control in robot belt grinding. First, according to the human grinding experimental data, the skilled worker’s arm impedance regulation is calculated. Next, the human skills are encapsulated as the statistical learning model where the kernel parameters are learned from the demonstration data by Gaussian process regression (GPR) algorithms. The desired profiles of robot are generated by the task planner based on the learned skill knowledge model. Lastly, the learned skill knowledge model is integrated with an adaptive hybrid position-force controller over the trajectory and force of end-effector in robot belt grinding task.

Findings

Manual grinding skills are represented and transferred to robot belt grinding for higher grinding quality of the workpiece.

Originality/value

The impedance of the manual grinding is estimated by k-means++ algorithm at different grinding phases. Manual grinding skills (e.g. trajectory, impedance regulation) are represented and modeled by GMM and GPR algorithms. The desired trajectory, force and impedance of robot are generated by the planner based on the learned skills knowledge model. An adaptive hybrid position-force controller is designed based on learned skill knowledge model. This paper proposes a torque-tracking controller to suppress the vibration in robot belt grinding process.

Details

Assembly Automation, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0144-5154

Keywords

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Article
Publication date: 25 July 2019

Jianjun Yuan, Yingjie Qian, Liming Gao, Zhaohan Yuan and Weiwei Wan

This paper aims to purpose an improved sensorless position-based force controller in gravitational direction for applications including polishing, milling and deburring.

Abstract

Purpose

This paper aims to purpose an improved sensorless position-based force controller in gravitational direction for applications including polishing, milling and deburring.

Design/methodology/approach

The first issue is the external force/torque estimation at end-effector. By using motor’s current information and Moore-Penrose generalized inverse matrix, it can be derived from the external torques of every joints for nonsingular cases. The second issue is the force control strategy which is based on position-based impedance control model. Two novel improvements were made to achieve a better performance. One is combination of impedance control and explicit force control. The other one is the real-time prediction of the surface’s shape allowing the controller adaptive to arbitrary surfaces.

Findings

The result of validation experiments indicates that the estimation of external force and prediction of surface’s shape are credible, and the position-based constant contact force controller in gravitational direction is functional. The accuracy of force tracking is adequate for targeted applications such as polishing, deburring and milling.

Originality/value

The value of this paper lies in three aspects which are sensorless external force estimation, the combination of impedance control and explicit force control and the independence of surface shape information achieved by real-time surface prediction.

Details

Assembly Automation, vol. 39 no. 3
Type: Research Article
ISSN: 0144-5154

Keywords

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Article
Publication date: 1 June 2005

L.E. Bruzzone, R.M. Molfino and M. Zoppi

Aims to discuss how impedancecontrolled parallel robots can effectively perform industrial assembly tasks.

Abstract

Purpose

Aims to discuss how impedancecontrolled parallel robots can effectively perform industrial assembly tasks.

Design/methodology/approach

A new purely translational parallel robot has been designed to fulfil the requirements of industrial assembly tasks. The kinematic and dynamic models of the robot have been obtained in analytic form. A full‐scale prototype has been realized within the Italian research programme PRIDE (Parallel Robots Interacting with Dynamic Environments). An impedance control algorithm based on the kinematic and dynamic models has been implemented on the control unit of the PRIDE prototype. The effectiveness of the impedancecontrolled PKM has been evaluated performing the assembly of white goods components.

Findings

The test results show that the combined use of impedance control and dynamic compensation applied to parallel kinematics machines allows to reduce remarkably the operational time compared to the currently used position‐controlled industrial robots.

Research limitations/implications

The experimental tests on the PRIDE prototype show the overall industrial feasibility of impedancecontrolled parallel kinematics machines.

Practical implications

The introduction of impedancecontrolled PKMs may improve, with a relatively low cost, the level of automation of several production plants in which delicate operations requiring force control are still executed manually.

Originality/value

While there is a large number of existing position‐controlled PKMs, the experimental research about force‐controlled or impedancecontrolled PKMs is not widespread.

Details

Industrial Robot: An International Journal, vol. 32 no. 3
Type: Research Article
ISSN: 0143-991X

Keywords

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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

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Article
Publication date: 7 May 2019

Adolfo Perrusquía, Wen Yu and Alberto Soria

The position/force control of the robot needs the parameters of the impedance model and generates the desired position from the contact force in the environment. When the…

Abstract

Purpose

The position/force control of the robot needs the parameters of the impedance model and generates the desired position from the contact force in the environment. When the environment is unknown, learning algorithms are needed to estimate both the desired force and the parameters of the impedance model.

Design/methodology/approach

In this paper, the authors use reinforcement learning to learn only the desired force, then they use proportional-integral-derivative admittance control to generate the desired position. The results of the experiment are presented to verify their approach.

Findings

The position error is minimized without knowing the environment or the impedance parameters. Another advantage of this simplified position/force control is that the transformation of the Cartesian space to the joint space by inverse kinematics is avoided by the feedback control mechanism. The stability of the closed-loop system is proven.

Originality/value

The position error is minimized without knowing the environment or the impedance parameters. The stability of the closed-loop system is proven.

Details

Industrial Robot: the international journal of robotics research and application, vol. 46 no. 2
Type: Research Article
ISSN: 0143-991X

Keywords

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