利用微控器於自走車避障之實現

The Implementation of an Obstacle Avoidance System for a Mobile Robot Using Microcontrollers

梁立柏(Li-Bo Liang)

指導教授 ： 陳建祥

國立清華大學/工學院/動力機械工程學系/碩士(2014年)

https://doi.org/10.6843/NTHU.2014.00205

摘要

本文以人工勢場法與離散滑動模式控制理論發展可用於自走式輪型機器人的避障演算法及運動控制器。以雷射測距儀為感測器感測環境資訊，在嵌入式微控制器為控制中心的平台上，自行設計一嵌入式自走機器人避障控制系統，並發展應用於輪型機器人的自動避障策略。
人工勢場法為一對障礙物及目標點座標建立虛擬能量場函數，以目標點座標為引力場中心，障礙物座標為斥力場中心，依據高勢能向低勢能變化，決定機器人向目標點移動路徑之方法。本文基於人工勢場法，提出修改型人工勢場法，改良機器人在逼近目標點時引力下降過快的問題。
本文分別以兩個微控制器實現避障策略演算系統與機器人驅動控制系統，設計Hokuyo URG04-LX雷射測距儀的驅動與資料解碼方法，並將其與避障演算法結合並實現於避障策略演算系統中，實現在資料傳輸時同時處理雷射測距儀資料，並能每0.1秒的週期擷取一次環境資料、完成避障策略的演算並產生新的運動命令。
機器人平台採用直流有刷伺服馬達為車輪致動器，本文應用離散滑動模式控制理論，在其強健性的基礎上，發展用於微控制器上的數位離散滑動模式控制律，並以梯形轉速規劃曲線為基礎，設計機器人的運動控制命令，以及機器人的座標及方向角計算方法。
實驗包含有機器人直線移動、修改型人工勢場法模擬與實驗，以及室內障礙物避障，其結果進一步驗證了系統的表現。

關鍵字

微控制器 ； 人工勢場法 ； 直流馬達 ； 輪型機器人 ； 避障 ； 雷射測距儀

並列摘要

In this thesis, the artificial potential field method is used to develop obstacle avoidance algorithm for autonomous wheeled robot and the discrete sliding mode control algorithm is applied to design motion controller for the robot. We designed an embedded obstacle avoidance system for autonomous mobile robot using laser range finder to scan environment range data sensor and implement the system on the microcontroller.
The artificial potential field approach established a path planning method for mobile robot moving to target without collision by introducing an attractive potential field at a target and a repulsive potential field at an obstacle which is closed to robot. Here, we designed a modified attractive potential field to improve the slow moving rate problem when robot is approaching the target based on the artificial potential field method .
The obstacle avoidance control system and robot motion control system were implemented separately using two different microcontrollers. We devised a protocol that transmits the Hokuyo URG04-LX laser range finder commands and decodes the range data as well. This system is combined with the obstacle avoidance algorithm to construct an obstacle avoidance strategy determination system. The system can also process the range data when the laser range finder is transferring scan data to our system and can manage a set of scan of range data and then use this data to compute the obstacle avoidance strategy and provide motion command to robot within a period of 0.1 second.
The robot platform of this thesis is equipped with two brushed DC motors as actuators. To claim robustness of mobile robot control, this thesis applied discrete-time sliding mode control scheme to both DC motors. The robot motion control command system and robot coordinate and orientation calculation method based on trapezoid velocity profile are designed.
The experiments carried out are straight-line movement of robot, the simulation and implementation of modified artificial potential field method and obstacle avoidance in indoor environment, and the results further verified the performance.

並列關鍵字

Microcontroller ； Artificial Potential Field Method ； DC motor ； Wheeled robot ； Obstacle avoidance ； Scanning laser range finder

參考文獻

[25] 楊甄寧，基於人工勢場之自走車避障策略之實現，國立清華大學動力機械工程學系碩士論文，中華民國一百零二年七月。

[24] 溫智凱，結合射頻辨識與二維雷射尋標儀於輪型機器人之追蹤與避障，國立清華大學動力機械工程學系碩士論文，中華民國一百零一年七月。

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