TECHNIQUE OF STRUCTURAL SYNTHESIS OF STATICALLY DETERMINABLE PARALLEL STRUCTURE MECHANISMS OF TECHNOLOGICAL ROBOTS
The article is devoted to improving the reliability and manufacturability of technological robots with parallel kinema- tics by replacing statically indeterminable manipulators with statically determinable mechanisms. The technique of structural synthesis of statically definable manipulators by modifying the structure of the prototype is proposed. The procedure involves identifying and eliminating redundant links, checking the solution. To determine the number of degrees of freedom of the mechanism, identify redundant links and verify the solution, the authors use the proposed methodology of structural analysis. In structural analysis, a manipulator is represented by a hierarchical structure and is considered as a parallel connection of elementary mechanisms with an open kinematic chain; as a kinematic chain consisting of leading and driven parts; as a set of links and kinematic pairs; as a kinematic connection of the output link and the rack. The article implements the following techniques for eliminating redundant links: mobility increase in kinematic pairs; introduction of unloading links and passive kinematic pairs to the kinematic chain; exclusion of extra links and pairs from the kinematic chain; increase in mobility in some kinematic pairs simultaneously with the exclusion of other kinematic pairs that have become superfluous. The authors developed several variants of structural schemes of self-aligning manipulators based on the Orthoglide mechanism. The proposed technique allows to determine the number of degrees of freedom of the mechanism, the number and type of redundant links, eliminate redundant links and, on an alternative basis, build structural diagrams of statically determinable mechanisms of technological robots with parallel kinematics.