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Modeling and Control Methods for Boundary Constrained Soft Robots
Title
Modeling and Control Methods for Boundary Constrained Soft Robots
Creator
Zhou, Qiyuan
Date
2021
Description
Soft and deformable robots have been an active field of research in the past few years. However, they are limited in that they cannot apply...
Show moreSoft and deformable robots have been an active field of research in the past few years. However, they are limited in that they cannot apply much force to an environment due to the limitations of the flexible materials from which they are made of. To help overcome this limitation, a new architecture named the Jamming and Morphing Enabled Bot Array (JAMoEBA) system was conceived. This system consists of a flexible outer membrane which encloses an interior composed of a granular medium. Active sub-units along the flexible outer membrane allow for actuation and locomotion of the system. The granular material coupled with the flexible outer membrane allows the robot to maintain the characteristics typically associated with soft robots (continuum, compliant, configurable). At the same time, the granular material is also able to undergo a solid phase transition with the application of pressure to the flexible outer membrane and allow the system to behave more like a rigid robot if needed. This allows for the robot system to exploit the desirable characteristics of both soft and rigid robots in its tasks.The purpose of this thesis is to offer a discussion and demonstration of various simulation methods for the physically accurate modeling of the JAMoEBA constrained boundary robotic system and to show some of the control methods which have been investigated within the selected modeling framework. Simulation methods based on Lennard-Jones (L-J) potentials, non-smooth contact dynamics (NSCD), as well as the discrete element methods based on complementarity (DEM-C) and penalty (DEM-P) conditions as implemented in the open source physics library Project Chrono are considered. Comparisons are made in the areas of physical accuracy, computational efficiency, and feature availability in the consideration of the best simulation method for the JAMoEBA system. Investigations of control strategies such as leader-follower and heuristics based approaches are carried out using the selected simulation method. Finally, a framework for self contained localization which relies on measurements from onboard sensors and linear Kalman filtering is tested within the simulation framework, and the effectiveness of approximating the shape of the JAMoEBA system using elliptical Fourier descriptors is shown.The main contributions made in this thesis are in the areas of suitable modeling methods, controls strategies, and localization techniques for the novel boundary constrained JAMoEBA soft robot architecture. The work done serves as a solid foundation for the future study of this novel soft robotic architecture due to the demonstration of successful methods for modeling, control, and localization of the system. The work presented is not meant to be a comprehensive or deep dive into any one specific area, but rather a jumping off point for future areas of research.
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