固定式起重機(Over-head Crane)為危險性機械(Dangerous Machine)之一，俗稱的天車是固定式起重機之一種，其操作動作是由升降捲動馬達、驅動馬達及軌道所組成，其動線和吊重皆有限制，如因操作不慎所衍生之工安事件，輕則造成作業人員受傷，重則導致財物損失及作業人員之傷亡。因此在操作時必須非常謹慎小心，對於荷重大小、路徑及作業四周環境等，均要確實瞭解掌握，才能確保作業安全與避免災害發生。
本論文是針對天車（Over-head Crane）設計預防撞擊人員或物品的安全警報裝置，並以影像處理技術，建立影像監控系統，使其能隨著吊掛物的上升、下降，自動追蹤目標物且維持警戒範圍與吊掛物之間的預設距離，並實際應用於天車吊掛預警防撞作業，必要時也能強制切斷天車之電源，預防吊掛物撞擊現場人員或其他設備，並利用透視投影、座標平移與旋轉技巧，進行障礙物與吊掛物之間的距離估測，使其成為一套安全性高的防撞監控系統。 The stationary crane is defined as dangerous machine by the law of Labor Safety and Health in R.O.C. The overhead crane is a kind of stationary cranes. It is an operating machinery to hang up/or down and transport the heavy goods in the industry. The overhead crane is composed of a winding motor, driving motor, track and control panel. It will be easy to get hurt or collision if the operator makes a mistake in the regular operation. Therefore, the operator must be very careful to handle all the lifting processes in order to ensure safety and avoid any disasters.
The thesis is aim at designing a pre-collision warning system, which cooperates with image processing technology to set a surveillance system. Such system is so advance that it can always keep proper distance between Over-head Crane and loading, even while the loading descend or ascend. However, to achieve such difficult goal, we have to comprehensively evaluate its safety standard. For instance, designer should consider the mechanism of emergency power switch, ensuring the crane can simultaneously cease without hurting worker. Beside, the utilization of geometric projection, translating or spinning coordination also plays an important role in this research. Only reaching above-mention condition, the standard can be approved as a safety pre-collision system.