Session: 16-01-01: Government Agency Student Poster Competition

Paper Number: 150441

150441 - Development of a 2-Dof Self-Decoupled Cable Driven Serial Robot 

Introduction: Cable-driven serial robots, known for their compact size and lightweight structure, present significant advantages in fields such as healthcare, aerospace, and architectural engineering. However, these robots face critical challenges: motion coupling, where the movement of one joint inadvertently affects other joints due to the interconnected cables, and different force and torque distributions compared to traditional cable-driven serial robots. This research presents a novel solution to motion coupling using non-circular pulleys, which compensate for the length changes in driving cables during joint movements. It also details the dynamics and control for a 2-DOF cable-driven serial robot based on this non-circular pulley.

Contribution: This work advances the development of cable-driven serial robots by introducing a novel motion-decoupled system. The innovative non-circular pulley design compensates for cable length changes, ensuring that the movement of one joint does not influence others. Dynamics of this robot are also analyzed to generate an efficient control system. This contribution is significant as it addresses a fundamental limitation in the current design of cable-driven robots and explores the different dynamics from traditional cable-driven serial robots. The introduction of this decoupling mechanism presents the way for broader applications in cable-driven serial robots fields, enhancing the operational capabilities and reliability of cable-driven serial robots.

Methodology: The research involves a detailed analysis and design process for the non-circular pulley. The profile of the non-circular pulley is calculated to ensure that it keeps the cable length nearly constant during joint movements. A 2-DOF cable-driven serial robot prototype with the non-circular pulley was designed and developed using the Denavit-Hartenberg (DH) convention for kinematic analysis and the Newton-Euler method for dynamic analysis. The control system integrates traditional PID, model-based control based on traditional cable-driven serial robots, and a novel model-based control tailored for the proposed dynamics. Experimental validation was conducted using high-resolution motion capture systems to compare the performance of these control strategies.

Results and Conclusions: Experimental results demonstrate the efficacy of the non-circular pulley mechanism in reducing motion coupling errors and achieving superior position accuracy compared to traditional control methods. A model-based control system was developed based on the proposed dynamics analysis, and validation was conducted by comparing this model with a traditional dynamics controller of a serial robot and a PID position control. The proposed model-based method achieves the smallest position errors, demonstrating its effectiveness. These findings validate the kinematic and dynamic models and confirm the effectiveness of the control system. The research concludes that the novel decoupling mechanism offers a practical solution to motion coupling in cable-driven serial robots, paving the way for their enhanced application in precision-demanding fields.

Presenting Author: Guodong Xiu Kent State University

Presenting Author Biography: Name: Guodong Xiu
Position: PhD Candidate at Kent State University
Educational Background: Guodong Xiu earned a Bachelor of Arts in Mechanical Engineering from the University of Jinan. He is currently pursuing a PhD at Kent State University.
Research Area: Guodong Xiu's research focuses on medical robots, aiming to develop and optimize advanced robotic systems for medical applications.
Current Research Project: Guodong is currently working on developing a new medical robotic system designed to improve the precision and safety of surgical procedures, potentially bringing revolutionary changes to the medical industry.

Authors:

Guodong Xiu Kent State University
Tao Shen Kent State University