Abstract
This paper describes a compensation device for joint motion errors, elastic displacements of the joints and links, and thermal deformations of the links. This device employs two rods connecting with the joints and a scale unit. The scale unit can measure the variation of the distance between the joints independently of the external load because the rods aren't subjected to the load. Moreover, temperature fluctuation has little effect on measured variation because the rods and the ball shank used in the spherical joints are made of Super Invar. This device was built in the experimental extensible limb of a coordinate measuring machine for micro parts. Experiments show that the device improves the stiffness and decreases the thermal expansion of the link.
