輪爪變形機器人應用於兩棲環境之偵搜

Abstract

本研究開發一水陸兩棲之輪爪變形機器人，可自由運行於平坦地形、崎嶇地形、水域環境以及水陸過渡環境之中。與前一代Clawheel III輪爪機器人相較，仍然沿用原先輪爪變形轉換的想法，進一步將機體改裝成具有防水之功能；加大輪爪寬度以及加入槳片，以提升水上推進力；並設計不同陸地步態，比較機器人質心起伏，選擇對機體振動較小的步態與控制方式；透過實驗證實機器人具有爬階與下階，以及陸地運行能力；於水域環境中能藉由實驗獲得的轉速轉換參數，操控機器人之轉向路徑。針對爪式步態、小跑步態、以及步行步態進行陸地步態研究。爪式步態適合克服較崎嶇的地形，然而應用於平坦的地形，機體則會有較大的起伏且受到較大的振動；採用小跑步態和步行步態則可以在平坦地形有較小的起伏，但越障的能力則不如爪式步態，並由模擬結果得知質心起伏的範圍，爪式步態為4公分，小跑步態與步行步態均為1.3公分；於陸地步態實驗中實現爪式步態與小跑步態，實驗過程一共經過10次步態週期，得到爪式步態與小跑步態平均每次步態週期機器人質心的起伏範圍分別為4.1公分和1.2公分，標準差分別為0.11公分和0.10公分。分析機器人輪爪轉動角與階梯地形的幾何關係，評估馬達的扭力需求，探討階梯與輪爪的尺寸規格對上下階初始位置的影響，並於實驗證實能成功上爬以及下爬階梯，平均上爬一階花費6秒，下爬一階花費9秒，上爬與下爬的輪爪轉速分別以每秒30度與每秒20度。水域環境的移動依靠轉動輪爪推進，並利用內側與外側輪爪轉速的差異改變移動方向，透過實驗得到的迴轉半徑與迴轉角速度，推算理論輪爪前進速度，得到轉速與理論速度之轉速轉換參數，藉此調控不同輪爪的轉速，以達到期待的迴轉半徑與迴轉角速度。

This research develops an amphibious claw-wheel transformable robot which could move on flat ground, uneven terrain, aquatic environment and semi-aquatic environment. Compared with Clawheel III, the previous generation claw-wheel transformable robot, Clawheel IV has waterproof chassis while retaining the claw-wheel transformable concept, and the width of the claw-wheel mechanism is extended and paddles are equipped so as to increase the thrust in water. Different kinds of gaits are designed and compared to reduce the oscillation of COG of robot and difficulty of control. Clawheel IV is proved to be capable of climbing and descending stairs and moving on land through experiments. Rotation-surge relative parameters are computed through turning experiments on water to control the turning path. Clawheel IV can use claw gait to adapt to uneven terrain, but the COG of the robot could result in larger oscillation while robot moves on flat ground; using trot gait and walk gait could reduce the oscillation of COG of robot, but have more limitation on uneven terrain. The ranges of COG oscillation when robot using claw gait, trot gait and walk gait are 4 cm, 1.3 cm and 1.3 cm respectively in simulation; in gait experiment, the ranges of COG oscillation are 4.1 cm and 1.2 cm when robot using claw gait and trot gait respectively. Moreover, geometric relations between the robot and stairs and the required motor torque are analyzed. In experiments, the robot can successfully climb up and descend down a stair, and it takes 6 sec/stair and 9 sec/stair in average with rotational speed at 30 deg/s and 20 deg/s respectively. Clawheel IV can change moving direction by rotating each claw-wheel at different rotational speeds. In experiments, rotating-surge relative parameters are computed, which could be used to control the rotational speed of claw-wheel to reach desired turning path.