Loop-by-loop modeling of whole-closed-loop 2D high-precision motion platform

A 2D high-precision motion unit plays an important role in an automatic optical inspection (AOI) system, and its positioning accuracy and speed have an decisive effect on the inspection accuracy, efficiency and stability of the AOI system, but the present AOI systems cannot ensure the high speed and high-precision at the same time. To solve this problem, an automatic optical platform is developed, using the whole-closed-loop, fast, high-precision positioning technology to construct the mathematical models of its motion control unit, including models of current loop, velocity loop and position loop from inside to outside. Experiments were made on the motion platform using a laser interferometer. Experimental results show that the 2D motion platform can be used to reach a scanning speed of 20m/s and a positioning accuracy of 9 mu m in a work area of 300mm * 3000mm with a load of 5kg.