Mathematical model of generalized coordinates of a working member of a multi-axis machine of a parallel structure with an excess drive
DOI:
https://doi.org/10.31548/dopovidi2018.04.020Abstract
A promising task of modern machine-tool construction is the creation of high-performance multi-coordinate milling machines and machining centers with ultra-high speeds and accelerations, which is possible with the use of mechanisms of a parallel structure. The full use of mechanisms of parallel structure in multi-coordinate manipulators with links of variable and constant length is hampered by certain shortcomings, the main of which is the limitation of the working space and the orientation angles of the working organ due to the occurrence of special positions. One way to solve this problem is to use redundant mechanisms of parallel structure that potentially reduce the impact of special provisions and fundamentally improve the characteristics of the workspace. Thus, the expansion of the technological capabilities of multi-axis parallel manipulators is an urgent scientific task.
The purpose of the article is to expand the technological capabilities of multi-axis parallel manipulators by introducing redundant drives.
The research is based on the main provisions of the theory of cutting materials, the theory of designing metal cutting equipment, research operations and decision-making.
As a result, a mathematical model has been obtained for calculating the lengths of the bar rods with six bars on the basis of parallel kinematic structures and the positions of the working element during the machining of the part.
When differentiating the obtained model with respect to time, the speeds and accelerations of the bars of the working element of the machine are obtained. For the case of contouring control, the calculation of new positions of the tool of the working element can go continuously with a time fragmentation by a certain step, or the original trajectory can be calculated in advance, as an array of data with subsequent loading into the controller, which cannot be done in other existing manipulators.
Keywords: multi-axis manipulators; redundant drive, parallel structureReferences
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