智慧型CAN-based汽車雷達防撞警告系統

Abstract

近年來由於科技的進步，在汽車駕駛安全上也越來越受到重視，透過車上電子感測器與雷射雷達，利用CAN bus完成車內的電子網路化架構與相對距離資料的訊號處理，建構一汽車週遭安全防撞警告系統，是本論文的目標。 論文中汽車防撞分為兩部分，一是關於車輛側、後方的防撞警告系統，用一智慧型方式來處理側、後方由倒車雷達所得到粗略距離資訊，判斷當有來車異常接近時，啟動警告；而安全時，解除警告訊號，為使用者做一友善判斷介面，在車內網路上透過CAN bus將側、後方端點的狀態傳送到主機端。 第二部分，車輛前方的防撞警告系統，利用雷射雷達來做距離量測，進一步以每兩筆相對距離資料除以間隔時間差來得到相對速度，由於車子本身的動態行駛與行進間震動問題，會造成相對速度受到干擾，這裡提出以一維的Kalman filter針對相對速度做估測，透過實驗數據調整輸入、輸出時系統狀態的white noise變異量，在速度估測運算上方便且容易實現。利用相對距離與相對速度之間的關係，提出一D/V曲線碰撞預先警告時間，可以有效地避免車輛前方碰撞。 另外，在車內網路架構上引入了CAN-based高階協定CANopen優點：網路監控，來確保CAN bus上每一個端點有效，建立一個穩健的防撞警告系統。

The goal of this thesis is to construct a collision-prevented system of vehicles by using the laser radar in the front and implementing three sets of commercial ultrasonic radars in rear and side. It mainly utilizes CAN bus to achieve the network frame for the vehicle. The first part of the collision-warning system focuses on the side and the rear approaching vehicles. Through the rough-estimated distance data from the back sonar ultrasonic sensors with 5 cm resolution within 150 cm, the proposed system will generate warning signals when other cars are approaching based on the developed algorithm. When the system judges that the condition is safe like in the traffic jam or waiting on the cross road, the developed system will automatically release the warning signal. CAN bus will also transmit the environmental condition of the vehicle to the drivers monitoring panel. The second part of the developed collision-warning system focuses on the collision avoidance system in the front of the vehicle by measuring the distance using laser radar within 80 meters. As the dynamic driving conditions are common, the relative speed can be directly obtained by the difference operation and can be further processed by applying the Kalman filter to estimate the relative speed more reliably. Experimental results indicate that the Kalman filter leads to more reliable results in speed estimation. Furthermore, a D/V curve is proposed that warning signals can be issued with a proper time in advance to prevent the collision. All warning systems are reliably implemented on a golf vehicle on CAN bus and its higher-layer protocol CANopen with self checking to improve the reliability of the proposed warning system.