System identification of a novel 6-DOF precision positioning table

The purpose of this study is to identify a novel 6-DOF precision positioning table, which is assembled by two different 3-DOF precision positioning tables: a plane-type 3-DOF (X, Y, θ_z) precision positioning table and a cylinder-type 3-DOF (θ_x, θ_y, Z) one. According to the dynamics of a mechanical mass-spring system, we establish simple mathematical equations that contain linear mass (inertia), viscous friction, and spring stiffness associated with cross-coupling effects due to mechanical bending. In system identification, we identify parameters of this 6-DOF and two 3-DOF precision positioning tables driven by piezoelectric actuators with hysteresis phenomenon, which is described by Bouc–Wen model. The identification method based on the real-coded genetic algorithm (RGA) has the advantages to identify all the parameters of the table and the hysteresis model simultaneously. From experimental results and numerical simulations, it is found that the numerically identified parameters are almost the same as those of the real system. In comparison of the identified results between the integral and individual tables, it is found that the integral table has better performance than those from the individual table.