Conventional serial and parallel robotic manipulators are well understood and have widespread use in applications ranging from autonomous manufacturing to flight simulator platforms. Cable-driven parallel robots are a relatively new class of robotic manipulators that have intriguing features, including a large workspace and high payload-to-weight-ratio, which have the potential to enable exciting new robotic applications. While these features are promising, high-acceleration maneuvers that take advantage of these properties are challenging and can even cause instability of the system if the end-effector pose is not known accurately and the feedback controller is not robust to large amounts of model uncertainty. In this talk, I will first discuss the development of a modular approach to modeling cable-driven parallel robots. A Rayleigh-Ritz discretization is used to develop a low-order model that captures the dominant structural modes of the flexible cables. The resulting model is modular, in the sense that any number of cables can be accommodated with arbitrary geometric configuration. I will then introduce forward kinematics methods that my group has developed that quantify the covariance of the end-effector pose estimation error, which are used within an extended Kalman filtering (EKF) framework with an end-effector-mounted inertial measurement unit (IMU) to obtain accurate pose estimates. Finally, I will present a passivity-based control method that is used to perform robust tracking of a desired end-effector trajectory. Numerical and experimental tracking results will be presented.

Ryan Caverly is an Assistant Professor in the Department of Aerospace Engineering and Mechanics at the University of Minnesota, Twin Cities. Dr. Caverly received his B.Eng. degree in Honours Mechanical Engineering from McGill University, and his M.Sc. and Ph.D. degrees in Aerospace Engineering from the University of Michigan, Ann Arbor. From 2017 to 2018 he worked as an intern and then a consultant for Mitsubishi Electric Research Laboratories in Cambridge, MA. Dr. Caverly is the recipient of a 2021 DoD Defense Established Program to Stimulate Competitive Research (DEPSCoR) Award to develop a unified testing and evaluation approach for hypersonic flight systems. He currently serves as an associate editor for IEEE Robotics and Automation Letters. Dr. Caverly's research interests include dynamic modeling and control systems, with a focus on robotic and aerospace applications, as well as robust and input-output control techniques.