A Study on Motion Planning of Four-Bar Mechanisms in the Presence of Singularities

Abstract

Type II singularities are a phenomenon encountered in closed kinematic chains. Characteristically, they lead to diverging actuator forces and loss of motion control. As a general solution to this problem, it is suggested in the literature that the dynamic model of the mechanism is made consistent at the singular configuration so that the singularity can be passed through smoothly. In line with this principle, the present paper analytically explores the guidelines for motion planning of four-bar mechanisms in the presence of type II singularities. With this purpose in mind, four theorems and two corollaries are developed and proved. Considering that four-bar mechanisms are widely used in various industrial applications, the theoretical outcomes of the paper are believed to be important also from a practical point of view.