Optimization of a three DOF translational platform for well-conditioned workspace

Stamper, R.; Tsai, Lung-Wen; Walsh, Greg

doi:10.1109/robot.1997.606784

Cited by 125 publications

(83 citation statements)

References 9 publications

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“…However, it was noticed that parallel robotic manipulators that are geared to the largest workspace can sometimes produce unwanted kinematic performances (e.g., bad dexterity). Thus, one scholar suggested to employ a global condition index [12] to handle the mentioned issue. The authors will resort to this index as formulated in Equation (15) to represent the performance of the manipulator's workspace.…”

Section: Pure Rotational Casementioning

confidence: 99%

Study on the Kinematic Performances and Optimization for Three Types of Parallel Manipulators

Zhang

Wei

2016

Machines

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Abstract:The modelling, optimization issues and stiffness for several types of three degrees-of-freedom parallel robotic manipulators, i.e., 3-DOF pure translational, 3-DOF pure rotational and 3-DOF mixed motion types, are studied in this paper. First of all, the kinematics and Jacobian for the robotic manipulators are determined through different approaches; secondly, objective functions modelling are presented, and the associated optimization issues and the geometric parameters' effect on the objective functions for the robotic mechanisms are illustrated and analyzed in detail. Through employing several multi-objective optimization approaches, we manifest an overall process and approach for multi-objective optimization of robotic systems. The correlation among different stiffness models is finally presented. The results indicate that the kinetostatic compliance model is the closest one to the traditional stiffness model.

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Section: Pure Rotational Casementioning

confidence: 99%

Study on the Kinematic Performances and Optimization for Three Types of Parallel Manipulators

Zhang

Wei

2016

Machines

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“…In Stamper et al (1997) it is stated that a parallel manipulator with maximum possible workspace may have undesirable characteristics such as low stiffness or resonance frequencies, which means that a multi-objective optimisation is needed. The multi-objective design optimisation problem is expressed as follows.…”

Section: Multi-objective Optimisationmentioning

confidence: 99%

Kinematic and Elastostatic Design Optimisation of the 3-DOF Gantry-Tau Parallel Kinematic Manipulator

Tyapin

Hovland

2009

MIC

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One of the main advantages of the Gantry-Tau machine is a large accessible workspace/footprint ratio compared to many other parallel machines. The Gantry-Tau improves this ration further by allowing a change of assembly mode without internal link collisions or collisions between the links and end-effector. The reconfigurable Gantry-Tau kinematic design obtained by multi-objective optimisation according to this paper gives the following features: 3-D workspace/footprint ratio is more than 3.19, lowest Cartesian stiffness in the workspace is 5N/µm and no link collisions detected. The optimisation parameters are the support frame lengths, the actuator positions and the robot's arm lengths. The results comparison between the evolutionary complex search algorithm and gradient-based method used for the Gantry-Tau design in the past is also presented in this paper. The detailed statics model analysis of the Gantry-Tau based on a functionally dependency is presented in this paper for the first time. Both the statics model and complex search algorithm may be applied for other 3-DOF Hexapods without major changes. The existing lab prototype of the Gantry-Tau was assembled and completed at the University of Agder, Norway.

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“…One usually desires a large workspace for parallel mechanisms, for example, having a large workspace capacity for parallel mechanisms used in machine tools usually indicates that the machine tool-head is able to stretch out to every corner of the work-piece when one is running milling, cutting, deburring, drilling, and finishing operations. In [19], a condition index was put forward as a criterion for optimizing the workspace for a three degree-of-freedom robotic mechanism for achieving a "well-conditioned" workspace performance. In [20] and [21], the volume of the workspace of robotic mechanisms was employed as a criterion for optimizing the workspace.…”

Section: Introductionmentioning

confidence: 99%

Interactions and Optimizations Analysis between Stiffness and Workspace of 3-UPU Robotic Mechanism

Zhang

Wei

2017

Measurement Science Review

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The interactions between stiffness and workspace performances are studied. The stiffness in x, y and z directions as well as the workspace of a 3-UPU mechanism are studied and optimized. The stiffness of the robotic system in every single moveable direction is measured and analyzed, and it is observed that in the case where one tries to make the x and y translational stiffness larger, the z directional stiffness will be reduced, i.e. the x and y translational stiffness contradicts with the one in z direction. Subsequently, the objective functions for the summation of the x and y translational stiffness and z directional stiffness are established and they are being optimized simultaneously. However, we later found that these two objectives are not in the same scale; a normalization of the objectives is thus taken into consideration. Meanwhile, the robotic system’s workspace is studied and optimized. Through comparing the stiffness landscape and the workspace volume landscape, it is also observed that the z translational stiffness shows the same changing tendency with the workspace volume’s changing tendency while the x and y translational stiffness shows the opposite changing tendency compared to the workspace volume’s. Via employing the Pareto front theory and differential evolution, the summation of the x and y translational stiffness and the volume of the workspace are being simultaneously optimized. Finally, the mechanism is employed to synthesize an exercise-walking machine for stroke patients.

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Optimization of a three DOF translational platform for well-conditioned workspace

Cited by 125 publications

References 9 publications

Study on the Kinematic Performances and Optimization for Three Types of Parallel Manipulators

Study on the Kinematic Performances and Optimization for Three Types of Parallel Manipulators

Kinematic and Elastostatic Design Optimisation of the 3-DOF Gantry-Tau Parallel Kinematic Manipulator

Interactions and Optimizations Analysis between Stiffness and Workspace of 3-UPU Robotic Mechanism

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