Design and control of two types of planar translational parallel manipulators with parallelogram mechanisms (ICCAS 2007)

In this paper, two types of novel planar translational parallel manipulators (TPMs) by using parallelogram mechanism are developed. One is made up of two Pa-P (parallelogram-prismatic) legs connecting the moving platform to the fixed base. The other consists of two P-Pa legs, which is the kinematic inversion of the former. Since connecting links in a parallelogram mechanism are subject to only tensile/compressive load and all the heavy actuators are mounted at the base, the proposed manipulators can be applied for planar positioning/assembly tasks requiring high stiffness and high speed. Especially, the 2-PaP TPM has the input-output decoupled characteristics, high velocity and large workspace. On the other hand, the 2-PPa TPM has high stiffness and high accuracy as well as high speed. The kinematic structure is explained, and the design methodology using prescribed workspace and velocity transmission capability is presented. Finally, two types of prototype manipulators and controllers have been developed.