Design of a cable-driven 2-DOF joint for dexterous robotic manipulator

Abstract

Most aircraft components are compact and it is hard for human to visually check them. The method of observing an aircraft machine is to disassemble it to achieve inspection and then reassembling back. The process of disassembly and assembly is highly time consuming. Therefore, significant research has been done on snake-like robotic arm due to its ability to access confined and constrained spaces.

Firstly, the joint between each module is the most critical part and it determines the functionality and capability of the whole robotic arm. Therefore, the aim of this work is to develop a 2-DOF joint for dexterous robotic arm. The new joint must be slim and light weight, no redundancy in actuation, and have simple kinematics modeling. The joint also requires less actuator which further reduces energy consumption. To fulfill the requirements, creative thinking and thorough analysis on joint design is required. A literature review has been conducted and summarized to compare the differences between various joint mechanisms of robotic arm. The cable-driven mechanism has met the design criteria in this project and is selected for further development. This report covers the design procedure of 2-DOF joint and base unit from brainstorming of ideas at initial stage, followed by concept formation, narrowing down of various designs to detailed designs. Structure analysis, result of prototype testing, discussion and further improvement on the selected 2-DOF joint design are discussed in this report. Calculation of forward and inverse kinematics has been carried out to study the behavior of the joint. From the Finite Element Analysis, the joint can withstand maximum applied force of 80N. Finally, the programme developed by Labview is used to control the motion of module tip. The prototype has light weight and the bending angles of two axes are 56 and 46 degreesrespectively.The testing of the prototype has been conducted and it can be concluded that the proposed 2-DOF joint is able to achieve the requirement.