Study on Inherent Error of Pair Control Methods for Six Axis Manipulator with Hidden Actuators

A six (6) axis manipulator generating three (3) translational and three (3) rotational motions with six (6) actuators mounted inside a rigid shell was designed, built, and is being operated in Reliability Assessment Center at Korea Institute of Machinery and Materials. Each of six actuators’ end cap is equipped with two types of hydrostatic bearing, one for plane sliding and the other for spherical sliding, which minimize the control effort by moving passively. And these special actuators are fitted in varying distances by themselves to maintain proper pressure for hydrostatic bearings. These special features allow easy manipulation of the machine compared to the conventional parallel type mechanisms. But, the simple control strategy used in this type of manipulators is embedding errors. In this article, the basic mechanism of this unique six (6) axis manipulator is introduced and the error is being studied.