Tree Climbing Robot: Design, Kinematics and Control

Climbing robots have become a hot research topic in recent decades. Most research in this area focuses on climbing manmade structures, such as vertical walls, glass windows, and structural frames. Little research has been conducted specifically on climbing natural structures such as trees. The nature of trees and manmade structures is very different. For example, trees have an irregular shape and their surface is not smooth. Some types of trees have soft bark that peels off easily. Hence, most of the climbing methods for manmade structures are not applicable to tree climbing.;Preventing trees from failing is important to protect human life and property in urban areas. Most trees in urban areas require regular maintenance. To reach the upper parts of a tree to perform such maintenance, workers need to climb the tree. However, tree climbing is dangerous, the development of a tree climbing robot is important to assist or replace humans works.;Several robots have been designed to climb trees such as WOODY and RiSE. However, these robots are limited to climbing straight tree trunks, and cannot climb trees that are curved or have branches. As branches and curvature are present in almost all trees, the application of these robots is strongly restricted.;As a result, this dissertation proposes a novel type of tree climbing robot, named Treebot, which has high maneuverability on trees. The design of Treebot was inspired by arboreal animals such as squirrels and inchworms. The applied extendable continuum maneuvering mechanism has large workspace and high degrees of freedom. It allows Treebot to perform various actions, such as moving between trunk and branches. Treebot is able to grip the surface of trees tightly with a wide range of gripping curvature. It enables Treebot to grip from a big tree trunk to small branches. The special gripping mechanism allows zero energy consumption in static gripping. Although Treebot has high maneuverability, it is compact, lightweight, and only five actuators are used in total. By installing proper equipments, Treebot can assist workers to perform forestry tasks such as inspection and maintenance. It can also be used as a mobile surveillance system to observe behaviors of both ground and arboreal animals.;In addition to presenting the mechanical design of Treebot, this dissertation also proposes several autonomous tree climbing algorithms. Making a robot climb a tree autonomously is a challenging task, as trees are complex and irregular in shape. However, a certain level of autonomous climbing ability is needed to simplify the operational use of Treebot. The proposed works include autonomous climbing on unknown environment and global path planning on known environment.