在加速度及速度限制下自動導引車於農業環境中的導引作業

本論文提出自動導引車在加速度及速度限制考量下於農業環境中作業的導引方法。為了簡化分析，發展一種簡單的互補圓弧表示法來模擬環境中的障礙物，而且以此互補圓弧之特徵點隨時間的變化來估測動態障礙物的速度。由於此自動車之驅動輪本身有角速度及角加速度的極限限制，因此自動車的轉向角、前進速度及加速度也相應受到限制，這種限制稱爲運動學限制；此外，爲避免與障礙物相撞，障礙物的存在狀態也會直接限制自動車的運動方式，這種障礙物存在空間的限制稱爲幾何限制。考慮運動學限制，推導出運動方程式，並將其結果繪在一前進速度對轉向角速度的規畫圖上，將此前進速度對轉向角速度規畫圖轉換成以前進速度對轉向角的座標系統表示，則幾何限制即可併到此規畫圖上一併討論，即將目地點的方位及障礙物的空間位置標示在圖上，根據此最終前進速度對轉向角的可行向量區及簡單的規則即可求得最佳瞬時導引速度及轉向角。最後，本研究以幾個例子驗證上述演算法，結果顯示此導引方法可以使自動導引車從起始點安全而迅速地到達目地點。

關鍵字

導引作業；自動導引車；運動學限制；幾何限制

並列摘要

The paper presented an approach for the guidance of an autonomous vehicle moving in agricultural environment under the consideration of velocity and acceleration constraints. To simplify the analysis, complementary sectors were used to simulate obstacles of any type in the environment. Also, the velocity of a moving obstacle was estimated by the position change of a characteristic point in the complementary sector. Due to the limitations on the angular velocity and acceleration of driving wheels, the steering angle and heading velocity of the autonomous vehicle were restricted correspondingly. This type of constraints was called kinematics constraint. For obstacle avoidance, the states of obstacles would affect the motion of vehicle. Constraints due to obstacles existence were called geometric constraints. Both geometric and kinematics constraints were taken into consideration in the study. Based on these constraints and some simple rules, feasible regions for heading velocity vs. steering angle were proposed to obtain the guidance algorithm of an autonomous vehicle. Several cases were studied to verify the proposed algorithm. From these cases, the algorithm developed was proved to be able to guide a vehicle safely and quickly toward a specified target from a starting point. The systematic way was expected to be useful for the guidance of autonomous vehicles moving in agricultural environment.

並列關鍵字

Guidance ； Autonomous vehicle ； Kinematics constraint ； Geometric constraint

國際替代計量

在加速度及速度限制下自動導引車於農業環境中的導引作業

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