Structural Analysis of Linkage Mechanisms of Hydraulic Manipulators

The structural schemes of hydraulic manipulators used in the roundwood handling operations are presented. The seventeen schemes of manipulators are considered. The characteristic technological processes are identified, the nominal motions of the attachment mounted on the manipulator are described and the structure of the manipulator used in each process is considered. The variety of structures of linkage mechanisms in manipulators is associated both with the accumulation of Assur groups and with the increase in the Assur group class. Mechanisms with the number of Assur groups up to 4 are used. Assur groups of 2nd and 3rd classes are mainly found in the mechanisms. Adding the degree of freedom to the manipulator is accompanied by emerging of an additional kinematic chain in the structure. The structures studied are divided into two groups: the first covers the structures in which the input links are attached to the column; the second consists of structures with internal inputs. Variants of additional classification features are proposed for structures with internal inputs. The known provisions of structural analysis as a whole allow the analysis to be performed if the internal input is separated out as an individual input link. Otherwise, it is necessary to correct the approaches to the structural analysis of mechanisms having internal input links

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