Singularity Analysis for 6-RSS Parallel Mechanism

The exact singular configurations of 6-RSS mechanism cannot be solved because of its numeric kinematics.A method to illustrate its singular configurations indirectly is presented.According to the performance of statics,a measure function,which has a clear physical meaning,has been defined to measure the proximity to singularities.Those configurations with a tiny value of proximity are called pseudo-singular configuration,and a solid model,called pseudo-singular space,can be used to gather all those pseudo-singular configurations.It can be deduced that the pseudo-singular space must contain the entire singular locus based on their definitions.Obviously,this pseudo-singular space can be used to illustrate all of the singular configurations indirectly.If the mechanism doesn't move into this pseudo-singular space,it cannot arrive at the singular configuration ever.Based on the mechanism kinematics and the measure function,the pseudo-singular spaces of the 6-RSS parallel mechanism under some constant-orientations are illustrated,which can support the singular data for specific applications.It is proved from the data of 6-RSS mechanism that the determination of Jacobian matrix cannot measure the proximity to singularities,and it also points out from the range of function value that Voglewede's constrained optimization function,which is similar to the method of this research,has some deficiencies,and a correction of which is made.