ERI: Exploration of the Design, Dynamics and Control of Self-Decoupled, Cable-Driven Serial Robots

Kent State University, Kent OH

Investigators

Abstract

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2). This Engineering Research Initiation (ERI) grant supports research that explores novel design, modeling and control methods for serial robots with fully cable-driven actuation. A serial robot is like a human arm. It consists of a series of rigid rod-like objects (analogous to human upper arm and forearm) and consecutively interconnected through joints (like an elbow). Serial robots are relatively compact in size and are easy to operate. Thus, serial robots are widely used in industrial automation, space exploration, medical services and many other applications. However, use of serial robots is quite limited in settings with restricted space to move and harsh environmental conditions. Space limitations dictate that robotic structures must be small, compact, and strong at the same time. These requirements are difficult to achieve with current robotics designs containing motors at their joints. While harsh conditions, such as heat or chemical exposure, can damage the electronic components and actuators directly installed on robotic joints. The fully cable-driven robot considered in this project will provide a potential solution to these two challenges. This design will situate electronic components and motors/actuators far away from any harsh elements and utilize cables/wires to transmit the power. However, the joints of a cable-driven serial robot are coupled by the cable transmission, and as such, the rotation of one robotic joint affects the motion of the other joints, making precise position control extremely challenging. This award supports fundamental research that will identify solutions for overcoming motion coupling issues in cable-driven serial robots, modeling the unique dynamics, and building a controller suitable for enabling this dynamic modeling. The knowledge acquired through this research will significantly enhance fundamental understanding of the control dynamics in complex coupling mechanisms and support more widespread use of cable-driven serial robots. The research team’s partnership with medical equipment industry will expand societal benefits of this work to medical robotics, thus advancing US economic prosperity and well-being. This robotics research will also help to broaden the participation of underrepresented groups in research, positively impact engineering education, and prepare students with industrial workforce skills. The knowledge gained through this research will improve the understanding of cable-driven actuation in serial robots, generate a method to realize the self-decoupling of the cable transmission, and create a paradigm for modeling and controlling cable-driven serial robots. In particular, the work (1) will evaluate the hypothesis that coupling can counter coupling to realize motion decoupling, and develop an advanced self-decoupling mechanism based on this hypothesis; (2) will model the robotic dynamics and build a force-position integrated controller for high-performance control; and (3) will prototype a robot based on this research to perform evaluation analysis. This project is supported by the cross-directorate Foundational Research in Robotics program, jointly managed and funded by the Directorates for Engineering (ENG) and Computer and Information Science and Engineering (CISE). This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.