利用雙眼視覺影像於室內場景之機器人同步定位與環境地圖建立

SLAM for Indoor Environment Using Stereo Vision

張洵豪(Hsun-Hao Chang)

指導教授 ： 陳永昌

國立清華大學/電機資訊學院/電機工程學系/碩士(2010年)

https://doi.org/10.6843/NTHU.2010.00520

摘要

近幾年，機器人的及時自我定位及建立環境地圖研究成為了一個重要的課題。行動自主機器人能夠及時自我定位及航行在未知環境中為是不可或缺的能力。傳統的定位方法為使用里程器傳回的資料去預測機器人所在的位置及方向，但是這種方法會隨著時間增加而誤差跟著累積。許多方法被提出用來修正誤差例如:粒子濾波器(Particle Filter)、卡爾曼濾波器(Kalman Filter)等等。在我們的時間中，使用的擴展型卡爾曼濾波器(Extended Kalman Filter)來修正定位誤差。
在這篇論文中，我們提出一個由雙眼視覺攝影機提取出影像的特徵，並利用雙眼視覺的特性求出這些線段的在三維空間中的垂直線的標的做為系統使用。為了處理測量上的不確定性，我們使用了兩種不同的觀察模型。其中一種是為了處理較近的標的點，另一種為處理較遠的標的點。這個系統包含了輪型機器人、里程器的資訊、影像線段萃取、標的點的座標轉換以及 Extended Kalman Filter 修正里程器誤差。
我們的方法可以利用單一感測器實現機器人即時定位，並且可以在材質較少的環境可以運作。機器人可以以 0.1m/s 的移動速度完成即時定位，系統誤差及運算時間也在可接受的合理範圍內。

關鍵字

機器人同步定位與建立地圖 ； 擴展式卡爾曼濾波器

並列摘要

In recent years, simultaneous localization and mapping (SLAM) becomes an important topic for robotic research. The ability that an autonomous mobile robot can simultaneously locate itself and navigate in an unknown indoor environment is indispensable. The simplest localization method only uses the odometer to estimate the robot position and pose, but the accumulated error is growing with the execution time of the system. Many algorithms can be used to reduce error like Particle Filter, Kalman Filter and so on. In our system, we use Extended Kalman Filter to revise the system error of SLAM problem.
In this thesis, we propose a system which extracts image line features from stereo camera as landmarks, and use stereo property to obtain the 3D vertical line landmarks. This system is based on the EKF. To handle with measurement uncertainty, we use two different observation models. One is nearby landmark model, the other one faraway landmark model. Our algorithm contains a wheeled robot, UBOT, which serves as our experiment platform, odometer data, image line segmentation, landmark’s 3D position reconstruction, and Extended Kalman Filter.
Our system can use a single sensor to implement the EKF-based SLAM in real time. It can work in an environment lacking texture. The robot moves at a speed of 0.1m/s and simultaneously locates itself. The estimated error and computational time of this system are acceptable.

並列關鍵字

SLAM ； Extended Kalman Filter

參考文獻

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