Vibration is one of the key factors affecting the machining precision of ultra-precision grating-ruling machines. In this study a structural model of the ultra-precision two-stage isolation system of a large grating-ruling engine is designed according to the vibration characteristics of the grating-ruling engine, and an active vibration control system adopting the fuzzy adaptive PID controller (FAPIDC) approach combined with an air-springs system is applied to realize high performance in controlling complex micro-vibration. The stability of PID control and the flexibility and adaptability of the fuzzy logic controller (FLC) are both combined for FAPIDC, because the optimal values of PID parameters are obtained by using fuzzy sets. The simulation results confirm that the two-stage vibration control system using fuzzy adaptive PID control strategy has good isolation performance against disturbance. The control system has fast dynamic response, high stabilization precision and strong adaptive robustness.

Based on the MSDV (the minimum sum of the displacement variance), the optimal combination of the bar group on a planar eight-link mechanical press is studied in this paper. Firstly, we establish the kinematic equations of a simplified planar eight-link by dividing the planar eight-link into three modules and resolving them step by step. With the established kinematic equations, we simulate the movement of the planar eight-link and obtain its curve of displacement, velocity and acceleration. Final, we get the optimal combination of the eight-link mechanical press based on MSDV. The simulation of the optimal planar eight-link bar group indicates that the displacement curves of the four eight-links included in a eight-link mechanical press almost coincide.