A study on multi DOF magnetic scale for motion control compensation of machine tool

Following to the previous paper reporting the motion control compensation for machine tool by 2 dimensional scale system, we hereby propose the Magnetic principle special scale for motion control compensation of machine tool. The authors investigated the compensation of the collateral movement orthogonal to the principle direction, which will affect the accuracy of the machine, by adding the orthogonal, 2-directional, short range measurement. The authors expected the improvement of compensation accuracy by continuously monitoring the relative motions between the movement of the bed and machine components with respect to the principle direction as well as to the direction of collateral movement, because the monitoring prompts re-acquisition of compensation data when the deviation from the initial compensation data becomes significant, enabling additional compensation for the dynamic motion error caused by cutting force etc. Firstly, this paper estimates the amount of motion error due to cutting force, the weight and acceleration force of the bed, using middle sized machine tool model. Then the paper presents the approximate required performance of the multi DOF scale. Finally, the paper reports the basic and elemental performance of magnetic multi DOF scales for motion error compensation, by prototyping the rotary scales.