Application of Full-Digital Coding scheme to Pneumatic Position Control

• Main Authors: Yi-Hao Yang, 楊翼豪
• Other Authors: Jyh-Chyang Renn
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/51819845599792190030

碩士 === 國立雲林科技大學 === 機械工程系碩士班 === 97 === The pneumatic control system is a highly non-linear and time-varying system. The system parameters would be changed by compressible gas, friction force, external interference. The pneumatic control system has the advantage of easy to get energy and maintain, Therefore nowadays it could widely be applied in industry. In this paper, a new Full-Digital Flow Control Unit (DFCU) consisting of several parallel-connected 2/2 on-off valves is designed. The basic operation principle of the developed DFCU is described briefly as follows. If the demanded volumetric flow is quite low, then only few on-off valves will be energized to supply low amount of pneumatic power to the system. On the other hand, if the positioning system demands large amount of pneumatic power, then more 2/2 on-off valves will be switched to ON position. This means that DFCU could use switch valve''s number to achieve the proportional control. In this study, the software LABVIEW is utilized to develop the control system. At feedback parts will utilize the laser or linear wire potentiometer to be the sensor of the experiment. Then, this paper will utilize four kinds of coding scheme, such as PNM coding (Pulse Number Modulation) and Binary coding. Moreover, Based on these two coding scheme, this paper proposes two novel coding schemes. The first coding is Mixed PNM-Binary coding, it tries to combine good characteristics binary and PNM coding. The second one is mixed coding scheme based on PNM . We use PID and Fuzzy controller to control number of the actuated on-off valves. At last the position control is accomplish. Besides, the DFCU has advantage of simple structure, low cost, noise reduction and long life. It expect to popularize in business in the future.