Computer simulation of a parallel structure manipulator for determining natural frequencies and oscillation modes

Abstract

The aim of the study is to develop and analyse computer models for determining the natural frequencies and oscillation modes of a planar parallel manipulator using the Universal Mechanism software package. The article is devoted to solving the problem of ensuring vibration resistance of robot manipulators. The novelty of the work lies in developing and analysing a computer model of a planar manipulator, in which solid bodies form joints with the number of freedom degrees in relative motion from 1 to 4; in determining the influence of the mass and link elasticity, as well as the type of kinematic pairs on natural frequencies and oscillation modes. As a result of the study, computer models of a planar manipulator with three degrees of freedom are developed. For these models natural frequencies and vibration modes are determined, the values of natural frequencies are compared with the known analytical solution, the influence of inertial and elastic properties of links, the number of excess links to natural frequencies and oscillation modes are established. The proposed computer model can be used to determine with sufficient accuracy the natural frequencies and oscillation modes of a planar parallel manipulator; a planar manipulator with weightless elastic rods and an elastic drive has six natural oscillation frequencies. Natural forms retain their shape for different values of the inertial and elastic parameters of the links. Oscillations of the platform on these forms in the horizontal and vertical planes are independent. The values of natural frequencies, at which the platform oscillates in the horizontal motion of the mechanism links, depend on the ratio of the drive stiffness coefficients and the bending stiffness of the rods. The values of natural frequencies, at which the platform oscillates in the vertical plane, depend on the bending and torsional stiffness of the rods and on the type of kinematic pairs in the mechanism scheme.