設備的衰退無法避免，而如何避免設備衰退所帶來的負面影響，則一直是製造業面臨的最重要課題之一。要確保良好的設備運作狀態，必須以預防性的角度進行設備保養。而唯有確實掌握設備運作狀態，才能最適切地執行保養。
由於目前可結合線上檢測儀器與電腦運算中心，對設備進行即時的監視與立即的控管，因此實現了動態預防保養策略(即在時間的變動下根據設備狀態立即決定最佳保養動作)應用的可能。
為建立動態預防保養策略，本研究要求：
(一)選定一適當的健康指標( Health Index )，由即時偵測所得到的設備參數，帶入公式得出當時的指標，
(二)將指標數值劃分為L個區，不同區代表不同設備狀態，
(三)以異質馬可夫鏈(Non-homogeneous Markovian chain)建模，
(四)設備在各個狀態下有多種維護動作可供選擇執行，
(五)考慮維護動作時間，(六)不考慮偵測時間，
(七)根據資料收集評估狀態轉移矩陣，
(八)以未來總成本現值最小化為目標，決定最佳維護策略。

It is an important concern for industries on how to avoid negative effects due to machine deteriorations and failures. Maintenance executed preventively is such a choice to maintain machine in proper operations. In nowadays technology, machine can be real-time monitored by equipping on-line inspecting equipments. Such equipments can be connected to a computer center which can help to determine the optimal action at each inspection time through a suitably designed algorithm. Hence, dynamic (real-time, time and state dependent) preventive maintenance policies can be realized or carried out.
The requirements for such a dynamic preventive maintenance policy are expressed as follows;
(1)Choose a suitable healthy index H. Such index can be calculated in terms of process parameters which can be obtained by inspection equipments.
(2)The system state can be determined by a suitably chosen
(3)The system can be modeled by a non-homogeneous Markov chain.
(4)Upon each state, several preventive actions can be chosen.
(5)The maintenance time is taken into consideration.
(6)The inspection is ignored.
(7)According to data collected, evaluates the transition probability matrices.
(8)The optimum maintenance policy is to choose at each inspection time the action which will have minimal expected total cost during a long time interval in the future.

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