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Reliable home error identification of a 2-DOF parallel robot based on regularization methods

PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART C-JOURNAL OF MECHANICAL ENGINEERING SCIENCE 2019年第7期233卷 2502-2515页

作者： Mei, Jiangping Zang, Jiawei Ding, Yabin Tianjin Univ Key Lab Mech Theory & Equipment Design Minist Educ Tianjin 300072 Peoples R China

This paper deals with the home error (the initial position error of active link) identification of a 2-DOF parallel robot. The identification model containing the home errors of the robot and the assembly errors of a new measuring instrument is developed using distance measurement. After that, an adaptive ridge regression method and a regularized Kalman filter method are proposed to improve the identification reliability and accuracy. Particularly, a modified L-curve method is proposed to provide suitable regularization parameters for the regularized Kalman filter. Based on the selected optimal measurement positions, experiments are carried out, in which the two regularized identification methods are compared with the ordinary ridge regression and the Kalman filter methods. Results show that the reliability and accuracy of the two methods are much better than the ordinary ridge regression method, and the divergence problem of the Kalman filter can be well resolved by the regularized Kalman filter.

关键词： parallel robot identification home error distance measurement regularization method

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Inverse Dynamics of a 3-P[2(US)] Translational parallel robot

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robotICA 2019年第4期37卷 708-728页

作者： Mazare, Mahmood Taghizadeh, Mostafa Najafi, M. Rasool Shahid Beheshti Univ Sch Mech Engn Tehran Iran Univ Qom Dept Mech Engn Qom Iran

In this paper, a type of parallel robot with three translational degrees of freedom is studied. Inverse and forward kinematic equations are extracted for position and velocity analyses. The dynamic model is derived by Lagrange's approach and the principle of virtual work and related computational algorithms implementing inverse and forward dynamics are presented. Furthermore, some numerical simulations are performed using the kinematic and dynamic models in which the results show good agreement with expected qualitative behavior of the mechanism. Comparisons with the results of work-energy and impulse-momentum methods quantitatively verify the validity of the derived equations of motion. Also, a relative computational effectiveness is observed in implementation of virtual work model via the simulations.

关键词： Kinematic modeling parallel robot Dynamic modeling Constrained system equations Virtual work

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Design, implementation, and performance evaluation of a 4-DOF parallel robot

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robotICA 2010年第1期28卷 107-118页

作者： Choi, Hee-Byoung Konno, Atsushi Uchiyama, Masaru Chungnam Natl Univ Taejon 305764 South Korea Tohoku Univ Dept Aerosp Engn Sendai Miyagi 9808579 Japan

This paper deals with the design, implementation, and performance evaluation of a new type of 4-DOF parallel mechanism providing three translations and one rotation for high-speed handling and machining. This parallel mechanism is named H4. A necessary condition and system configuration of the H4 are also described. Hardware and kinematics of the H4 is addressed and the manipulability ellipsoid which is one of the widely used methods to examine the design of parallel mechanisms is addressed. The performance evaluation is carried out to demonstrate the H4 robot. The Simulation and experimental results show that three different controllers, the PD, PD + velocity feed-forward, and dynamic compensation controller, dramatically improve the trajectory tracking accuracy.

关键词： Design parallel robot 4-DOF

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parallel robot for micro assembly with integrated innovative optical 3D-sensor

Parallel robot for micro assembly with integrated innovative...

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Conference on Optomechatronic Systems III

作者： Hesselbach, J Ispas, D Pokar, G Soetebier, S Tutsch, B Tech Univ Braunschweig Inst Werkzeugmaschinen & Fertigungstech D-3300 Braunschweig Germany

ISBN: (纸本)0819446890

Recent advances in the fields of MEMS and MOEMS often require precise assembly of very small parts with an accuracy of a few microns. In order to meet this demand, a new approach using a robot based on parallel mechanisms in combination with a novel 3D-vision system has been chosen. The planar parallel robot structure with 2 DOF provides a high resolution in the XY-plane. It carries two additional serial axes for linear and rotational movement in/about z direction. In order to achieve high precision as well as good dynamic capabilities, the drive concept for the parallel (main) axes incorporates air bearings in combination with a linear electric servo motors. High accuracy position feedback is provided by optical encoders with a resolution of 0.1 mum. To allow for visualization and visual control of assembly processes, a camera module fits into the hollow tool head. It consists of a miniature CCD camera and a light source. In addition a modular gripper support is integrated into the tool head. To increase the accuracy a control loop based on an optoelectronic sensor will be implemented. As a result of an in-depth analysis of different approaches a photogrammetric system using one single camera and special beam-splitting optics was chosen. A pattern of elliptical marks is applied to the surfaces of workpiece and gripper. Using a model-based recognition algorithm the image processing software-identifies the gripper and the workpiece and determines their relative position. A deviation vector is calculated and fed into the robot control to guide the gripper.

关键词： micro assembly parallel robot optical 3D-sensor

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Natural frequency modulation of a kinematically redundant planar parallel robot

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PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART C-JOURNAL OF MECHANICAL ENGINEERING SCIENCE 2022年第9期236卷 4805-4817页

作者： Gu, Jiawei Xie, Zhijiang Zhang, Jian Pi, Yangjun Chongqing Univ Coll Mech & Vehicle Engn 74 Shazheng St Chongqing 400044 Peoples R China Chongqing Univ State Key Lab Mech Transmiss Chongqing Peoples R China

When a parallel robot is equipped with kinematic redundancy, it has sufficient capabilities of natural frequency modulation through adjusting geometric configuration. To reduce resonance of a mechanism, this paper investigates the natural frequency modulation of a kinematically redundant planar parallel robot. A double-threshold searching method is proposed for controlling the inverse kinematics solution and keeping the natural frequencies away from the excitation frequency. The effectiveness of modulating the natural frequencies is demonstrated by comparing it with a non-modulation method. The simulation results indicate that, in all directions, the responses are coupled, and every order should be taken into consideration during natural frequency modulation. Compared to the non-modulation method, the proposed method can reduce the resonance amplitude to a certain extent, and the effect of vibration suppression is remarkable.

关键词： Natural frequency modulation kinematic redundancy parallel robot resonance amplitude

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Error attenuation in the control of a parallel robot manipulator using a dual-model-based structure

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PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART C-JOURNAL OF MECHANICAL ENGINEERING SCIENCE 2003年第2期217卷 161-171页

作者： Li, Q Nanyang Technol Univ Sch Mech & Prod Engn Singapore 639798 Singapore

parallel structure robots have been receiving growing attention from both academia and industry in recent years. This is due to their advantages over serial structure robots, such as high stiffness, high motion accuracy and a high load-structure ratio. Control of parallel robots, however, produces difficulties to control engineers due to the modelling errors arising from the highly nonlinear and complex structures. This paper proposes a dual-model-based structure for error attenuation in the trajectory-tracking control of a parallel robot manipulator. In this design, a conventional model-based control algorithm employing an estimated robot dynamic model is first implemented in the inner loop of the control structure. Then, in order to reduce the unwanted effects caused by modelling errors, another model-based structure, developed based on the concept of the internal model control, is appended in the outer loop of the control structure as a compensator. A combination of these two model-based components results in a novel dual-model-based structure for parallel robot control. Sensitivity analyses show that the effects due to modelling errors and external disturbances can be significantly reduced by applying this new control structure without relying on a high-gain control solution. The effectiveness of this control design is successfully demonstrated by numerical studies on a planar parallel robot with 2 degrees of freedom.

关键词： robust control model-based control internal model control parallel robot

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Fault-tolerant control based on adaptive super-twisting nonsingular integral-type terminal sliding mode for a delta parallel robot

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JOURNAL OF THE BRAZILIAN SOCIETY OF MECHANICAL SCIENCES AND ENGINEERING 2020年第8期42卷 1-15页

作者： Mazare, Mahmood Taghizadeh, Mostafa Ghaf-Ghanbari, Pegah Shahid Beheshti Univ Sch Mech Engn POB *** Tehran Iran

External disturbances, internal uncertainties and actuator faults with an unknown range have detrimental effects on controller performance of industrial robots. In this paper, to deal with such challenges, a new fault-tolerant control (FTC) strategy using a combination of nonsingular integral-type terminal sliding mode (NITSM) and adaptive high-order super-twisting (AST) control is proposed for a delta-type parallel robot. To eliminate the chattering of sliding mode controller as a key ingredient of excessive energy consumption and convergence rate reduction, high-order algorithm is applied. Stability analysis of the closed-loop system is performed using Lyapunov theory. Moreover, to achieve optimal performance, controller parameters are obtained using harmony search algorithm (HSA) by minimizing an objective function consisting of integral time absolute error (ITAE) and control signal rate. The proposed controller performance is compared with conventional sliding mode and feedback linearization control methods. The obtained results reveal the superiority of the proposed AST-NITSM.

关键词： Fault-tolerant control parallel robot Terminal sliding mode Finite-time convergence

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Dynamics and vibration of a 3-(P)under-barSP parallel robot with flexible moving platform

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JOURNAL OF VIBRATION AND CONTROL 2016年第4期22卷 1095-1116页

作者： Sharifnia, Mahdi Akbarzadeh, Alireza Ferdowsi Univ Mashhad Dept Mech Engn Ctr Excellence Soft Comp & Intelligent Informat P Mashhad 0098 Iran

In this research, first an analytical model is presented for dynamic and vibration analysis of a 3-PSP parallel robot with a flexible moving platform. Next, the presented analytical model is solved using an approximate analytical method. The moving platform is assumed to be made of three Euler-Bernoulli beams joined together to form a star. Each of the three beams of the star slides through a passive prismatic joint. Then, three-dimensional vibration analysis of the flexible moving platform, star, with three passive prismatic joints is the main subject of the present research. Only vibration during free motion is considered. Therefore, it is assumed that only inertia forces of the star are the main source of its vibration. First, direct kinematics is used for acceleration analysis of the rigid robot and inertia forces are obtained. For dynamic modeling, the passive prismatic joints and junction point of the three beams are modeled using a new set of geometric constraints. Additionally, a previously developed constrained motion equation for a planar Euler-Bernoulli beam having a prismatic joint is further developed for the three beams of the star. Next, an approximate analytical solution method, called the constrained assumed modes method, is used for inverse dynamics and vibration analysis of the robot. Furthermore, the developed model can be used for direct dynamics analysis of the robot. Finally, several input trajectories and two different groups of mode shapes are considered to investigate the model efficiency. The results of the presented model are compared with the results of a commercial finite element method software.

关键词： Assumed modes flexible parallel robot prismatic joint vibration

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Improved Image Based Visual Servoing with parallel robot

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JOURNAL OF INTELLIGENT & robotIC SYSTEMS 2008年第4期53卷 359-379页

作者： Qi, Zhen McInroy, John E. Univ Wyoming Dept Elect & Comp Engn Laramie WY 82071 USA

The position regulation problem of an eye-in-hand type of parallel robot based pointing systems (PRBPS) is considered in this paper. A fuzzy logic system is first designed to compensate for the uncertainties of the parallel robot and the uncertainty of the image Jacobian, then a hybrid controller (HC) including the image-based nonlinear controller and the adaptive supervisory fuzzy logic controller (ASFLC) is derived by using the Lyapunov direct method to realize the position regulation (PR). The stability of the closed-loop system in the Lyapunov sense is proven theoretically. The fuzzy scaling matrix is combined with the HC to improve the performance of the control system. The simulation results demonstrate that the PRBPS realizes PR with very good robustness to the parameter uncertainties, and the control input torques and settling time are reduce greatly in the case of large initial feature errors.

关键词： parallel robot Position regulation Image Jacobian Adaptive supervisory fuzzy logic controller Fuzzy scaling matrix Settling time

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A Force-Controlled parallel robot for Large-Range Stiffness Rendering in Three Dimensions

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IEEE robotICS AND AUTOMATION LETTERS 2022年第2期7卷 1340-1347页

作者： Lai, Yu-Hsuan Huang, Sheng-Yuan Lan, Chao-Chieh Natl Cheng Kung Univ Dept Mech Engn Tainan 700701 Taiwan

A haptic device is used to transmit impedance to a human user to mimic the impedance of a virtual or real environment. Existing haptic devices use serial or parallel robots to deliver impedance in multiple dimensions. These robots usually have non-constant Jacobian matrices that result in poor dynamic properties and low impedance stability limits in certain regions within the workspace. To account for these regions, the range of stiffness rendering is limited. This letter presents a three-degrees-of-freedom (DoFs) translational parallel robot with a constant Jacobian matrix in the entire workspace. The consistent dynamic parameters allow a large-range virtual stiffness to be rendered. To provide the accurate and large output force required for high-stiffness rendering, series elastic actuators (SEAs) are used as the input for the parallel robot. SEAs can be used to minimize the geartrain friction and effective inertia to control the output force and impedance more accurately. Design, modeling, and three-dimensional impedance control of the haptic device are presented in this work. Multi-dimensional impedance and virtual-wall control experiments are illustrated to demonstrate the accuracy and rendering range of the haptic device. Since the stable range of virtual stiffness is much larger than existing ones, it is expected that this novel device can be used to render accurate stiffness for both soft and stiff environments.

关键词： parallel robot Jacobian matrix force control series elastic actuator haptic device stiffness rendering

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