Performance analysis of 3-PPRU parallel mechanism with a completely/partially/non constant Jacobian matrix

This paper proposes a 3-PPRU parallel mechanism (PM) with a completely/partially/non constant Jacobian matrix. Based on screw theory and selecting actuating components theory, the reasonability of the actuating input selection is analyzed. By different actuating selection, the Jacobian matrix of the PM can realize completely/partially/non constant. The direct, inverse and combined kinematic singularities of the PM with three different Jacobian matrices are discussed. The velocity, payload and stiffness performance of the PM are discussed and compared. A new index, as auxiliary evaluation index, is proposed first.