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Too often systems fail, sometimes leading to significant loss of life, fortunes and confidence in the provider of a product or service. It was determined that a simple and useful tool was needed to help in the analysis of interactions of groups and systems to determine possible unexpected consequences. The tool didn’t need to provide every possible outcome of the interactions but needed to provide a means for analysts and product/service development stakeholders to evaluate the potential risks associated with implementing new functionality in a system. They needed a brainstorming tool to help ascertain if a concept was viable from a business perspective. The control–feedback–abort loop and the analysis diagram is one such tool that has helped organizations analyze their system workflows and workflow exceptions. The concept of the Control–Feedback–Abort (CFA) loop is based upon another concept called the ‘''Control – Feedback Loop. The Control – Feedback Loop has been around for many years and was the key concept in the development of many electronic designs such as ''Phase-Lock Loops''.〔Azais, F.; Bertrand, Y.; Renovell, M.; Ivanov, A.; Tabatabaei, S, “An all-digital DFT scheme for testing catastrophic faults in PLLs”, Design & Test of Computers, IEEE, 20, No. 1, (2003) 60–67〕 The core of the CFA loop concept was based on a major need that corporate executives and staff can anticipate the operation of systems, processes, products and services they use and create before they are developed.〔Theron R. Leishman, Dr. David A. Cook, “Requirements Risks Can Drown Software Projects”, CrossTalk – The Journal of Defense Software Engineering, April 2002 Issue, 1–8〕 ==History of CFA loop concept== The concept of the CFA loop was developed by T. James LeDoux, ‘Jim’, a Senior Consultant and software QA / test expert and owner of (Alpha Group 3 LLC ), a test management consulting company. In 1986, Mr. LeDoux, with assistance from Mr. Warren Yates, a former engineer from General Dynamics, Inc., found that using a Control and Feedback concept for analyzing group and system dynamics was not providing them with the full picture when systems were going out of control. In 1996, Jim LeDoux and Dr. Larry W. Smith, Ph.D., president of Remote Testing Services, Inc., discussed the issue at length and came to the conclusion that some other form of control must be present when a system goes out of control, even if the control is unintended. In 1997, Mr. LeDoux used the change of behavior a person exhibits when driving a car at the time a police car pulls in behind them to describe how a change of control occurs. He demonstrated this phenomenon at a 2003 Product Development and Management Association (PDMA) meeting in Denver by showing the action of the first control (traffic, signs and speed) being aborted by the driver and a second control (police car, signs and speed) becoming the primary control. In 2004, Mr. LeDoux worked with Dr. Susan Wheeler, Ed. D., a former Instructional Design Consultant with Nims, Inc. and the present Director of Technology Services at (Illinois Central College ), to identify the range of uses for the CFA Loop. The CFA Loop is now being used to analyze system activities in several Fortune 100 companies. A discussion of its use is also included in the management book “Takeoff!: The Introduction to Project Management Book that Will Make Your Projects Take Off and Fly!” by Dr. Dan Price, D.M.〔Dr. Dan Price, Takeoff, (Colorado: Winning Ways Management, 2005), Pages 184–198〕 ISBN 978-0-9707461-1-5 It was found that strong similarities existed between the concept of ‘''Control Charts''’ and the CFA Loop. The difference in the two concepts was that control charting is used as a dynamic measurement of present conditions. The CFA Loop is used to analyze how a closed-loop system is supposed to work and what are the expectations when alternate controls take over by either intent or accident. A comparison of the CFA Loop and its relationship to Control Charts are presented in a later section of this discussion. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Control–feedback–abort loop」の詳細全文を読む スポンサード リンク
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