System identification of a Scott–Russell amplifying mechanism with offset driven by a piezoelectric actuator

The micro-positioning Scott–Russell (SR) mechanism driven by a piezoelectric actuator (PA) is designed to magnify the displacement of the PA. The main feature of the SR mechanism is its straight-line output for a given input displacement. In this paper, the main objective is to propose a complete mathematical model, including the driving circuit, Bouc–Wen hysteresis and mechanical equation, to describe the system. In system identification, the real-coded genetic algorithm (RGA) is adopted to find the parameters of the SR mechanism and the PA. From the comparisons between numerically identified dynamic responses and experimental results, it is found that the error percentages are within −1.4% ∼ 1.7% for the system without offset and −3.85% ∼ 3.33% for the system with offset. It is concluded that the numerically identified parameters of the complete model are almost the same as those of the real system, and the RGA method is feasible for the identification of the SR mechanism driven by the PA.