Applying System Dynamics on Several Human Machine Interface Systems

• Main Authors: Yi-Zeng Lin, 林益增
• Other Authors: Jao-Jia Horng
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/57877906055322523427

碩士 === 國立雲林科技大學 === 環境與安全衛生工程系 === 104 === As manufacture technology advanced to Industrial 4.0, new technologies were rapidly introduced into our life and work environment. Due to the obvious limitations of the traditional hazard and incident analysis, Professor Leveson proposed a Systems-Theoretic Accident Modeling and Processes (STAMP) that focused on the interactions these components and analyzed the possible hazards of automation and mechanics. This study used it to investigate several cases of human-machine interactions, such as the building elevator, the fluid flow experiment unit, the inflow system of wastewater treatment plant (WWTP), and the input system of incinerator. Using STAMP as analytical tool, this study systematically analyzed the possible hazards, limitations, and cause-effect of machine operation. Through the use of system simulation software VENSIM, the cause-effect model could be established and define system hazards. The Systems Theoretic Process Analysis (STPA) was used to identify the hazardous control factors and to find the possible causes of system failures. As those results cross-checked with the cause-effect model, the safety limitations were proposed to reduce the system risks. The elevator system used the lifting speed as the indicator to study the effects of loading changes. The inappropriate operation could cause the rapid up or down as slipping phenomena due to the malfunction of sensors. The fluid flow system used the water-hammer pressure as the indicator to study the effects of water-hammer pressure by the electric ratio valve changing flow rate. The pipe leakages were caused by operational malfunctions due to the in-correct operation of components or the inappropriate parameter settings. The inflow system of WWTP used the pump well levels as the indicator to study the overflow effects druing abrupt storm-flow. Except the inappropriate setting of well level or sensor interferences, the design faults could also induce the system failures. The incinerator system used the chamber temperature as the indicator to study the temperature effects by the garbage moisture contents on the input system. If the temperature monitoring was inappropriated by sensor’s errors or malfunction, the incineration and co-generation efficiency would be lowered. Summarily, STPA showed that all kinds of sensors would play the keys of human-machine interface, control and safety. By cause-effect models and safety limitations, we could effectively reduce all kinds of system risks.