Nonlinear-Dynamic-Analysis Based Fuzzy PID Control Approach for Complex Hydraulic Driving Process

The strong nonlinearity of the hydraulic driving process for forging makes it difficult to achieve accurate control. In this paper, we propose a nonlinear-dynamic-analysis based Fuzzy PID control approach for this complex process. Unlike the existing control methods that are designed specifically for a given work piece, this proposed control method can be effectively used in the forging of different work pieces. A model of the closed-loop forging system is first derived and a solving method is then developed in order to find the model solution. Using this model solution, the dynamics of the closed-loop forging system is further estimated and the conditions for stability, vibration, and creep, as well as the relationships between the controller parameters and the constraints are also derived. These derived dynamic characteristics, conditions and relationships for different work pieces are further integrated and used to design the controller. Through the use of experiments and simulations on a practical forging system, the effectiveness of all of these analytical results and the designed controller is finally demonstrated.