| 摘要 |
A first lift stand is provided with a first supporting unit to support a first portion of a positioning object, and a first servo system to drive the first supporting unit in a vertical direction. A second lift stand is provided with a second supporting unit to support a second portion of the positioning object, and a second servo system to drive the second supporting unit in the vertical direction. A third lift stand is provided with a third supporting unit to support a third portion of the positioning object, and a third servo system to drive the third supporting unit in the vertical direction. A fourth lift stand is provided with a fourth supporting unit to support a fourth portion of the positioning object, and a fourth servo system to drive the fourth supporting unit in the vertical direction. |
