Research And Design Of The Control System For The Middle-convex And Varying Ellipse Piston Turning

Middle-convex and varying ellipse piston is one of the key parts of internal combustion engines, which becomes an important task in the researching domain of the piston. Giant Magnetostrictive Actuator (GMA) is a kind of actuators with highly efficiency of conversion of magnetic energy to mechanical energy with the advantages of large force, high resolution and quick response, etc. Currently, Giant Magnetostrictive Actuator (GMA) becomes research focus in the field of precision actuation.Taking the piston turning processing as the background, the state of its application to micro actuation was presented. On the basis of Ferromagnetics, the current strength and the displacement of the static relationship of Giant Magnetostrictive Actuator is analyzed. Then the dynamic model of GMA was established based on the mechanics principle, and the transfer function of the GMA constant current source was established with laplace domain property testing method.The controller of the middle-convex and varying ellipse piston which based on C8051F020as the core was founded. The design of the micro displacement detection circuit, output circircuit of the GMA controlling signal, memory unit, USB interface circuit and other components of the controller hardware circuits was complacted. By using the C51language, the control software was developed, including the module of system monitoring main program, setting value calculation and other related function modules, and achieved data acquisition processing and control function, realized the closed-loop control of the giant magnetostrictive actuator displacement with high precision.According to the characteristic of the large-time delay of GMA system, the control algorithm is on the way.At first, the PID controller containing Smith compensation structure was designed. Compared with the traditional PID controller, the simulation results shows that Smith-PID controller can greatly improve the response speed of the system.But as the parameters of the system model in the operation process changing, Smith-PID controller will become bad quality.Then the Fuzzy Adaptive PID controller was designed, and combined Smith-PID and Fuzzy Adaptive PID controller. The simulation results show that the Fuzzy adaptive PID controller with Smith can well meet the demand of fast responsing of middle convex and varying ellipse piston turning.To realize the turning processing of the section about middle-convex and varying ellipse piston, firstly, we should analyze the charcacteristics of its section, and then provide proper mathematical descriotion. Based on the character of the middle-convex and varying ellipse piston with complex transverse and longitudinal section contour, the method of direct function interpolation algorithm based on elliptic parameter equation and polynomial fitting was used to get a turning tools trackong function.Through the experiment, this method is simple and can satisfy the middle-convex and varying ellipse piston turning requirements.