Design Synthesis of a three legged SPS Parallel Manipulator

This paper shows the design analysis of a non conventional parallel manipulator of 3-SPS (Spherical-Prismatic Spherical) configuration. This configuration is selected with the aim to enhance the manipulator workspace and dexterity in a table-top scale pod. The minimum number of limbs can be three in a parallel kinematic machine (PKM). The limb interference is reduced in a three limb structure unlike the six limbs configuration in the Stewart platform. In contrast, the stiffness is compromised in this structure as the platform cannot take load while standing on three ball joints. In order to deal with this issue, self-lockable spherical joints are designed to be incorporated into the 3-SPS system. The table-top size PKM manipulator is prototyped with the self-lockable spherical joints and its working performance is checked.