Abstract
The workspace of a spatial 6-DOF electro- hydraulic parallel manipulator is strongly coupled, due to its multi-closed-loop kinematic structure and the coupling complicates motion planning and control of the parallel manipulator. This paper clearly analyses the strong dynamic coupling property in the workspace of a spatial 6-DOF parallel manipulator, using modal decoupling theory and a frequency responses characteristics analysis method. The dynamic model of a spatial 6-DOF electro-hydraulic parallel manipulator is expressed with the Kane method and hydromechanics principles. The modal analysis method is used to establish the map between strong coupling workspace and decoupled modal space and the dynamic coupling relationship and coupling strength between workspaces are exactly revealed. The quantitative evaluation index of dynamic coupling is presented. Moreover, the relationship between dynamic coupling effects and input is discussed through applying frequency characteristics analysis. Experimental results show the workspace of the parallel manipulator is strongly coupled and the coupling property is coincident with theoretical results.
Highlights
Parallel manipulators have been extensively investigated due to their high force‐to‐weight, high stiffness, high accuracy and widespread applications in various fields, such as high fidelity simulators, space docking motion systems and machine tools [1,2,3,4]
The main aim of this paper is to provide theoretical foundation in order to develop a method to solve the dynamic coupling effects for a spatial 6‐DOF parallel manipulator, via clearly revealing the dynamic coupling phenomenon, dynamic coupling relationship and the dynamic coupling strength of a spatial 6‐DOF electro‐ hydraulic parallel manipulator with a novel coupling analysis approach
This paper investigates the dynamic coupling of a spatial 6‐DOF electro‐hydraulic parallel manipulator, with a view to derive the theoretical foundation of developing an effective method to eliminate the effects of dynamic coupling on a spatial 6‐DOF electro‐hydraulic parallel manipulator
Summary
Parallel manipulators have been extensively investigated due to their high force‐to‐weight, high stiffness, high accuracy and widespread applications in various fields, such as high fidelity simulators, space docking motion systems and machine tools [1,2,3,4]. A spatial 6‐DOF electro‐ hydraulic parallel manipulator is often used as a spatial multi‐DOF motion and load system with a heavy payload for its special loading capacity. The dynamic coupling effects of a spatial 6‐DOF electro‐hydraulic parallel manipulator can be summarized in two aspects. One is that the 6‐DOF electric‐hydraulic parallel manipulator is a six‐input‐six‐ output system, but each channel is coupled with another due to dynamic coupling, it is very hard to realize the independent controller design in each channel of workspace or joint space. With respect to the spatial 6‐DOF electro‐hydraulic parallel manipulator, the entire control performance and potential is limited and restricted by dynamic coupling. To develop a decoupled structure or decoupled control technique for a electro‐ hydraulic parallel manipulator, the analysis of dynamic coupling is very important and significant
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