Translational shaking tests achieved on a 6-DOF hydraulic parallel manipulator

Purpose – The paper aims to achieve translational shaking tests on a 6-DOF hydraulic parallel manipulator. Shaking tests are commonly performed on shaking tables, which are generally used for small motion ranges and are usually financially costly. The research is required to generate shaking motions in three translational directions for a specimen for shaking tests, but it also needs to produce 6-degree of freedom (DOF) motions with large motion ranges. Design/methodology/approach – A hydraulic 6-DOF (degree of freedom) parallel manipulator is applied to achieve this goal. The link-space control is adopted for the manipulator, and PID controller and feed-forward controller are used for each loop of the system. A hybrid reference signal generator is proposed by using a shaking controller, which is developed to convert the shaking motion into position signal. The converted result is directly added to the pose signal. The whole real-time control system is realized by using MATLAB xPC Target. Findings – The developed method is verified on the hydraulic 6-DOF parallel manipulator with specimen. Experiments show very promising results that the proposed technology is really applicable to perform translational shaking tests on the hydraulic parallel manipulator. Originality/value – A simple yet efficient solution is proposed that allows shaking tests in three translational directions performed on the hydraulic 6-DOF parallel manipulator with wide motion ranges. The paper presents a state-of-the-art related to the applications of parallel robots in several fields of technology.

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Forward Kinematic Analysis of Kinematically Redundant Hybrid Parallel Robots

Journal of Mechanisms and Robotics ◽

10.1115/1.4047176 ◽

2020 ◽

Vol 12 (6) ◽

Author(s):

Kefei Wen ◽

Clément M. Gosselin

Keyword(s):

Real Time ◽

Unique Solution ◽

Kinematic Analysis ◽

Parallel Robots ◽

Degree Of Freedom ◽

Real Time Control ◽

The Real ◽

Time Control ◽

Forward Kinematic Problem ◽

Forward Kinematic

Abstract This paper focuses on the forward kinematic analysis of (6 + 3)-degree-of-freedom kinematically redundant hybrid parallel robots. Because all of the singularities are avoidable, the robot can cover a very large orientational workspace. The control of the robot requires the solution of the direct kinematic problem using the actuator encoder data as inputs. Seven different approaches of solving the forward kinematic problem based on different numbers of extra encoders are developed. It is revealed that five of these methods can produce a unique solution analytically or numerically. An example is given to validate the feasibility of these approaches. One of the provided approaches is applied to the real-time control of a prototype of the robot. It is also revealed that the proposed approaches can be applied to other kinematically redundant hybrid parallel robots proposed by the authors.

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A singularity handling algorithm based on operational space control for six-degree-of-freedom anthropomorphic manipulators

International Journal of Advanced Robotic Systems ◽

10.1177/1729881419858910 ◽

2019 ◽

Vol 16 (3) ◽

pp. 172988141985891

Author(s):

Zhi-Hao Kang ◽

Ching-An Cheng ◽

Han-Pang Huang

Keyword(s):

Null Space ◽

Singularity Analysis ◽

Degree Of Freedom ◽

Control Input ◽

Real Time Control ◽

Time Control ◽

Operational Space ◽

Industrial Manipulators ◽

Space Motion ◽

Six Degree Of Freedom

In this article, we analyze the singularities of six-degree-of-freedom anthropomorphic manipulators and design a singularity handling algorithm that can smoothly go through singular regions. We show that the boundary singularity and the internal singularity points of six-degree-of-freedom anthropomorphic manipulators can be identified through a singularity analysis, although they do not possess the nice kinematic decoupling property as six-degree-of-freedom industrial manipulators. Based on this discovery, our algorithm adopts a switching strategy to handle these two cases. For boundary singularities, the algorithm modifies the control input to fold the manipulator back from the singular straight posture. For internal singularities, the algorithm controls the manipulator with null space motion. We show that this strategy allows a manipulator to move within singular regions and back to non-singular regions, so the usable workspace is increased compared with conventional approaches. The proposed algorithm is validated in simulations and real-time control experiments.

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Dynamic modeling, system identification and comparative study of various control strategies for a spatial parallel manipulator

Proceedings of the Institution of Mechanical Engineers Part I Journal of Systems and Control Engineering ◽

10.1177/09596518211032075 ◽

2021 ◽

pp. 095965182110320

Author(s):

Mervin Joe Thomas ◽

Shoby George ◽

Deepak Sreedharan ◽

ML Joy ◽

AP Sudheer

Keyword(s):

Real Time ◽

Parallel Manipulator ◽

Control Strategies ◽

Proportional Integral Derivative ◽

Real Time Control ◽

Model Predictive Controller ◽

End Effector ◽

Proportional Integral ◽

Time Control ◽

Predictive Controller

The significant challenges seen with the mathematical modeling and control of spatial parallel manipulators are its difficulty in the kinematic formulation and the inability to real-time control. The analytical approaches for the determination of the kinematic solutions are computationally expensive. This is due to the passive joints, solvability issues with non-linear equations, and inherent kinematic constraints within the manipulator architecture. Therefore, this article concentrates on an artificial neural network–based system identification approach to resolve the complexities of mathematical formulations. Moreover, the low computation time with neural networks adds up to its advantage of real-time control. Besides, this article compares the performance of a constant gain proportional–integral–derivative (PID), variable gain proportional–integral–derivative, model predictive controller, and a cascade controller with combined variable proportional–integral–derivative and model predictive controller for real-time tracking of the end-effector. The control strategies are simulated on the Simulink model of a 6-degree-of-freedom 3-PPSS (P—prismatic; S—spherical) parallel manipulator. The simulation and real-time experiments performed on the fabricated manipulator prototype indicate that the proposed cascade controller with position and velocity compensation is an appropriate method for accurate tracking along the desired path. Also, training the network using the experimentally generated data set incorporates the mechanical joint approximations and link deformities present in the fabricated model into the predicted results. In addition, this article showcases the application of Euler–Lagrangian formalism on the 3-PPSS parallel manipulator for its dynamic model incorporating the system constraints. The Lagrangian multipliers include the influence of the constraint forces acting on the manipulator platform. For completeness, the analytical model results have been verified using ADAMS for a pre-defined end-effector trajectory.

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Real-time control and application with self-tuning PID-type fuzzy adaptive controller of an inverted pendulum

Industrial Robot the international journal of robotics research and application ◽

10.1108/ir-10-2018-0206 ◽

2019 ◽

Vol 46 (1) ◽

pp. 159-170 ◽

Cited By ~ 9

Author(s):

Tayfun Abut ◽

Servet Soyguder

Keyword(s):

Real Time ◽

Inverted Pendulum ◽

Adaptive Controller ◽

Performance Criteria ◽

Real Time Control ◽

Content Type ◽

Time Control ◽

Self Tuning ◽

Fuzzy Adaptive Controller ◽

Fuzzy Adaptive

PurposeThis paper aims to keep the pendulum on the linear moving car vertically balanced and to bring the car to the equilibrium position with the designed controllers.Design/methodology/approachAs inverted pendulum systems are structurally unstable and nonlinear dynamic systems, they are important mechanisms used in engineering and technological developments to apply control techniques on these systems and to develop control algorithms, thus ensuring that the controllers designed for real-time balancing of these systems have certain performance criteria and the selection of each controller method according to performance criteria in the presence of destructive effects is very helpful in getting information about applying the methods to other systems.FindingsAs a result, the designed controllers are implemented on a real-time and real system, and the performance results of the system are obtained graphically, compared and analyzed.Originality/valueIn this study, motion equations of a linear inverted pendulum system are obtained, and classical and artificial intelligence adaptive control algorithms are designed and implemented for real-time control. Classic proportional-integral-derivative (PID) controller, fuzzy logic controller and PID-type Fuzzy adaptive controller methods are used to control the system. Self-tuning PID-type fuzzy adaptive controller was used first in the literature search and success results have been obtained. In this regard, the authors have the idea that this work is an innovative aspect of real-time with self-tuning PID-type fuzzy adaptive controller.

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Fuzzy logic-based real-time control for a twin-rotor MIMO system using GA-based optimization

World Journal of Engineering ◽

10.1108/wje-03-2017-0075 ◽

2018 ◽

Vol 15 (2) ◽

pp. 192-204 ◽

Cited By ~ 2

Author(s):

Arpit Jain ◽

Satya Sheel ◽

Piyush Kuchhal

Keyword(s):

Fuzzy Logic ◽

Real Time ◽

Mimo System ◽

System Optimization ◽

Mathematical Function ◽

Real Time Control ◽

Content Type ◽

Time Control ◽

Non Linear System ◽

Twin Rotor

Purpose The purpose of this paper is to study the application of entropy based optimized fuzzy logic control for a real-time non-linear system. Optimization of the fuzzy membership function (MF) is one of the most explored areas for performance improvement of the fuzzy logic controllers (FLC). Conversely, majority of previous works are motivated on choosing an optimized shape for the MF, while on the other hand the support of fuzzy set is not accounted. Design/methodology/approach The proposed investigation provides the optimal support for predefined MFs by using genetic algorithms-based optimization of fuzzy entropy-based objective function. Findings The experimental results obtained indicate an improvement in the performance of the controller which includes improvement in error indices, transient and steady-state parameters. The applicability of proposed algorithm has been verified through real-time control of the twin rotor multiple-input, multiple-output system (TRMS). Research limitations/implications The proposed algorithm has been used for the optimization of triangular sets, and can also be used for the optimization of other fussy sets, such as Gaussian, s-function, etc. Practical implications The proposed optimization can be combined with other algorithms which optimize the mathematical function (shape), and a potent optimization tool for designing of the FLC can be formulated. Originality/value This paper presents the application of a new optimized FLC which is tested for control of pitch and yaw angles in a TRMS. The performance of the proposed optimized FLC shows significant improvement when compared with standard references.

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Dynamic Control of Curve-Constrained Hyper-Redundant Manipulators

Journal of Robotics and Mechatronics ◽

10.20965/jrm.2004.p0001 ◽

2004 ◽

Vol 16 (1) ◽

pp. 1-7 ◽

Cited By ~ 2

Author(s):

Shugen Ma ◽

◽

Mitsuru Watanabe ◽

Keyword(s):

Degrees Of Freedom ◽

Dynamic Control ◽

Redundant Manipulators ◽

Redundant Manipulator ◽

Real Time Control ◽

Feed Forward ◽

Manipulator Dynamics ◽

Time Control ◽

Control Scheme ◽

Feed Forward Controller

Hyper-redundant manipulators have high number of kinematic degrees of freedom, and possess unconventional features such as the ability to enter narrow spaces while avoiding obstacles. To control these hyper-redundant manipulators accurately, manipulator dynamics should be considered. This is, however, time-comsuming and makes implementation of real-time control difficult. In this paper, we propose a dynamic control scheme for hyper-redundant manipulators, which is based on analysis in defined posture space where three parameters were used to determine the manipulator posture. Manipulator dynamics are modeled on the parameterized form with the parameter of the posture space path. The posture space path-tracking feed-forward controller is then formulated on the basis of a parameterized dynamic equation. Computer simulation, in which a hyper-redundant manipulator traces the posture space path well by using the proposed feed-forward controller, proved that the hyper-redundant manipulator tracks the workspace path accurately.

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A Family of Novel Lower-Mobility Decoupled Parallel Mechanisms

Volume 8: 31st Mechanisms and Robotics Conference, Parts A and B ◽

10.1115/detc2007-34202 ◽

2007 ◽

Cited By ~ 1

Author(s):

Daxing Zeng ◽

Sijun Zhu ◽

Zhen Huang

Keyword(s):

Real Time ◽

Basic Feature ◽

Degree Of Freedom ◽

Parallel Mechanisms ◽

Real Time Control ◽

Motion Feature ◽

Time Control ◽

Fixed Base ◽

Lower Mobility ◽

Moving Platform

This paper presents a family of novel lower-mobility decoupled parallel mechanisms (DPMs), which consists of one 5-DOF (degree of freedom) DPM, two 4-DOF DPMs, three 3-DOF DPMs, and three 2-DOF DPMs. The basic feature of this family is that the moving platform and the fixed base of the DPMs are connected by two limbs and the motion of the moving platform is fully decoupled. Then the constraint screw method is used to analyze the motion feature of all DPMs presented in this paper. The mobility of these DPMs has also been calculated by the Modified Grubler-Kutzbach criterion. All the DPMs in this paper are simple and no computation is required for real-time control.

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Kinematic analysis and design of a six D.O.F. 3-PRPS in-parallel manipulator

Robotica ◽

10.1017/s0263574799001368 ◽

1999 ◽

Vol 17 (3) ◽

pp. 269-281 ◽

Cited By ~ 15

Author(s):

J.H. Shim ◽

D.S. Kwon ◽

H.S. Cho

Keyword(s):

Kinematic Analysis ◽

Parallel Manipulator ◽

Kinematic Model ◽

Real Time Control ◽

Analysis And Design ◽

Pure Rotation ◽

Time Control ◽

Active Compliance ◽

Design Characteristics ◽

And Performance

This paper presents a kinematic analysis and design characteristics of an in-parallel manipulator developed for the probing task application that requires high precision, active compliance, and high control bandwidth. The developed manipulator is a class of six-degree-of-freedom in-parallel platforms with 3 PRPS (prismatic-revolute-prismatic-spherical joints) chain geometry. The main advantages of this manipulator, compared with the typical Stewart platform type, are the capability of pure rotation generation and the easy prediction of the moving platform motion. The purpose of this paper is to develop an efficient kinematic model which can be used for real-time control and to propose systematic methods to design the manipulator considering workspace, manipulability, resistivity, singularity, and the existence conditions of the forward kinematic solution. Particularly, we propose a new method for checking the singularity of the parallel manipulator using the translational and rotational resistivity measures. A series of simulation are carried out to show kinematic characteristics and performance of the manipulator mechanism. A prototype manipulator was built based on the kinematic analysis results.

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Towards achieving a fully intelligent robotic arc welding: a review

Industrial Robot the international journal of robotics research and application ◽

10.1108/ir-03-2015-0053 ◽

2015 ◽

Vol 42 (5) ◽

pp. 475-484 ◽

Cited By ~ 14

Author(s):

John Ogbemhe ◽

Khumbulani Mpofu

Keyword(s):

Trajectory Planning ◽

Arc Welding ◽

Optimization Methods ◽

Seam Tracking ◽

Real Time Control ◽

Content Type ◽

Time Control ◽

Robotic Arc Welding ◽

Welding Automation ◽

And Control

Purpose – The purpose of this paper is to review the progress made in arc welding automation using trajectory planning, seam tracking and control methodologies. Design/methodology/approach – This paper discusses key issues in trajectory planning towards achieving full automation of arc welding robots. The identified issues in trajectory planning are real-time control, optimization methods, seam tracking and control methodologies. Recent research is considered and brief conclusions are drawn. Findings – The major difficulty towards realizing a fully intelligent robotic arc welding system remains an optimal blend and good understanding of trajectory planning, seam tracking and advanced control methodologies. An intelligent trajectory tracking ability is strongly required in robotic arc welding, due to the positional errors caused by several disturbances that prevent the development of quality welds. An exciting prospect will be the creation of an effective hybrid optimization technique which is expected to lead to new scientific knowledge by combining robotic systems with artificial intelligence. Originality/value – This paper illustrates the vital role played by optimization methods for trajectory design in arc robotic welding automation, especially the non-gradient approaches (those based on certain characteristics and behaviour of biological, molecular, swarm of insects and neurobiological systems). Effective trajectory planning techniques leading to real-time control and sensing systems leading to seam tracking have also been studied.

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