由於道路車輛數目的快速增加，加上現代面臨的行車干擾比起往常更為多樣繁雜，除了如隨身攜帶的行動手機外，車載機視聽娛樂等都會影響駕駛人使得駕駛人分心，交通意外事故頻頻發生，因此智慧型運輸系統(Intelligent Transportation System)的研究因應發展，其中汽車駕駛安全警示系統更是研究重點之一。
本研究探討利用多個低價位之超音波感測器，偵測外來車輛與本車之間的直線距離及夾角，並分別計算出外來車輛與本車之間在縱軸與橫軸上的距離，以進行一縱軸碰撞時間及一橫軸碰撞時間的計算，配合偵測碰撞策略之比對，以正確計算出碰撞時間；藉此避免因為兩車交會、平行或超車所造成本車警示系統的誤判，進而提升車輛防側撞的警示準確度。

Due to the road vehicle density increase and driving interference caused by the mobile phone and vehicle entertainment system, the traffic accidents occurring frequency is increasing obviously. The intelligent
transportation system and the driver impact warning safety system are proposed to improve this problem. Here a sensor array composed with multi ultra-sonic sensors is proposed to detect the distance and the angle between the target vehicle and the driving vehicle mass center and driving direction, respectively. Then the lateral and longitudinal distances between two vehicles can be derived to calculate the time to collision, x TTC and y TTC , respectively for judging the real collision danger. It can be used to eliminate the fault impact warning of the vehicle parallel driving and safe overtaking conditions. This strategy and structure has low cost and accurate impact warning performance for practical implementation purpose.