Singularity Analysis of a 6-PRRS Parallel Robot Based on Geometrical Method

Three types of singularities have been analyzed for a 6-PRRS parallel robot in this paper, i.e., the forward, inverse, and combined singularity. Conventional analysis method of a parallel robot is based on the whole Jacobian matrix, so it needs complex process and computation. The singularity analysis in this paper focuses on the geometrical character of one motion chain, and every chain is processed by the same method, so the complexity of singularity analysis is significantly reduced. Using the product-of-exponential formula, the kinematics equations possess algebraic character so that the inverse singularity analysis algorithms can be readily and systematically formulated. By analyzing the instantaneous mobility of the moving platform, the necessary and sufficient geometrical conditions for the forward singularity configurations are identified. It has shown that these methods can be used for singularity analysis of various parallel robots