Modeling Dynamics and Exploring Control of a Single-Wheeled Dynamically Stable Mobile Robot with Arms

Abstract

This paper focuses on simulations of a dynamically stable mobile robot (Ballbot) with arms. The simulations are of Ballbot lifting its arms in various directions. A PD arm controller works independently of an LQR-designed balancing/station keeping controller. The PD controller drives the arms to follow desired trajectories. When the arms are raised, Ballbot assumes a leaning equilibrium (the physical equilibrium) as opposed to the standing equilibrium (body stands totally upright- a predefined desired equilibrium) that the LQR drives toward. The conflict between these two equilibria causes the robot to lose its balance when lifting heavy (10 kg) loads. A unified arm and station keeping/balancing controller is also described. The unified controller outperforms the independent controllers in some cases. Balancing only using arms and driving body movement with arms are briefly explored. I Acknowledgments Thanks to my advisor, Dr. Ralph Hollis for his vision in creating Ballbot and guiding my work. Thanks to Dr. George Kantor for constant technical advice and brainstorming. Thanks to Anish Mampetta for his companionship and ideas through all of our experimenting with Ballbot. Anish was also the first to derive the Ballbot motion equations using the current coordinates. Thanks to Dr. Matt Mason and Jonathan Hurst for reviewing my work as part of my committee. Thanks to my family, friends, and classmates for every day