The Kinematics Study of a 7 DOF Serial Robotic Manipulator for Obstacle Avoidance Purpose

Lim, Cheng Wei (2020) The Kinematics Study of a 7 DOF Serial Robotic Manipulator for Obstacle Avoidance Purpose. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

Obstacle avoidance for mobile robots is a topic which has been widely discussed under various context. However, obstacle avoidance for serial manipulator has seldom been a topic of discussion. This project reviews the robotic manipulator kinematics solutions and proposes its application at obstacle avoidance. This study is important as the implementation of obstacle avoidance for a high degree-of-freedom (more than 6 DOF) serial robotic manipulator is yet common. This project aims to design a 7 DOF serial robotic manipulator and derive its kinematic equations for obstacle avoidance purpose. To achieve the aim, a research of three main steps was carried out. Firstly, a 7 DOF serial robotic manipulator was designed with its kinematic frames assigned to each joint following the rules of Denavit-Hartenberg (DH). Secondly, the forward and inverse kinematics equations were formulated for this robot. Forward kinematics equations were formed using a DH parameter table and inverse kinematics were formulated using the mixture of geometrical and analytical approaches, namely kinematics decoupling. Lastly, the inverse kinematics equations were verified in MATLAB ROBOTIC TOOLBOX for the functionality of its inverse kinematics equations and its obstacle avoidance ability. As a result, this project has successfully formulated the inverse kinematics equations for this robot. The validation of the results showed that the outputs from the inverse kinematics equations were valid and could be verified by the forward kinematics and the MATLAB ROBOTIC TOOLBOX. However, a main limitation found in the inverse kinematics equation derived in this project using the kinematics decoupling method was the joint angle of joint 6 (θ6) always give a result of zero degree of rotation. It has limited the movement range of the robot. Future research can be further developed to improve the inverse kinematics of this robot. As a conclusion, this project has designed a 7 DOF serial manipulator with its forward and inverse kinematics equations formulated. The inverse kinematics equations were tested valid in MATLAB ROBOTIC TOOLBOX with its ability of avoid obstacles.