Development Of Fieldbus-based Electric Actuator Control System

Because of the developments of the automation instrumentation industry, the performances of electric actuator will be better and better. At the same time, the application of electric actuators will be wider and wider as the market demand of valves is rising. With the developments of the technology of microelectronics, sensors, communications network and mechatronics, electric actuator will enter a digital, intelligent and network era.The intelligent electric actuator based on fieldbus is composed of intelligent controller and actuator. The intelligent controller that joined by SCM and FCS is used to control the valve switch. It can not only receive analog signals from regulators, but also receive digital signals from PC. Then these signals are changed to angular displacement or linear displacement to drive the valves. Because of these, the controller can make the process controlling come true. Actuator is composed of motor, shift gear and valve.This paper dwells on three parts which is the design of hardware circuit of the controller, software of the controller and interface of the PC. The core of the controller is ADuC812 SCM. And photoelectricity seclusion input and output circuit, limit circuit, independent power circuit, high reliability motor drive circuit, accurate position feedback circuit and flexible human-machine interface circuit are used. Software of the controller is composed of self-adjusting program, control algorithm program, human-machine exchange of information program, serial communication program which use RS485 as its communication protocol, etc. VC.NET is used in the interface of the PC. This interface has high visibility, and it can monitor the operation of the actuator. At the same time, the electric actuator control system is tested. And the design of the software and hardware of the system is proved correctly by the test results. At the end of this paper, the existing problems are analyzed. Against these problems, a new kind of intelligent electric actuator based on Optical-mechanical-electrical integration is put forward, and its operation methods are given.