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UBC Theses and Dissertations

Dynamics and control of a novel manipulator with deployable and slewing links Zhang, Jian


The thesis investigates the planar dynamics and control of a novel, flexible, multimodule manipulator with slewing and deployable links, which may be used in space - as well as ground - based operations. The system is composed of a flexible orbiting platform supporting two modules connected in a chain topology. Each module consists of two links: one free to slew while the other permitted to deploy and retrieve. There are three major aspects to the study. To begin with, a detailed dynamical response study is undertaken which assesses the influence of initial conditions, system parameters, and manipulator maneuvers on the system response. Results suggest that, under critical combinations of parameters, the response may not conform to the acceptable limit. This points to a need for active control. Next, the study focuses on the behavior of the system using two different control methodologies: (i) the nonlinear Feedback Linearization Technique (FLT) applied to rigid degrees of freedom with flexible generalized coordinates indirectly regulated through coupling; (ii) an integration of the FLT and Linear Quadratic Regulator (LQR) to achieve active control of both rigid and flexible degrees of freedom. Finally, the thesis presents the development of an intelligent hierarchical system for the vibration control of the manipulator. The emphasis is on the use of knowledge-based tuning of the low-level direct controller so as to improve the performance of the control system. For this purpose, first a fuzzy inference system (FIS) is developed. The FIS is then combined with a conventional modal controller to construct a hierarchical control system. Specifically, a knowledge-based fuzzy system is used to tune the parameters of the modal controller. The effectiveness of the hierarchical control system is assessed through simulation studies. Results show that the knowledge-based hierarchical control system is quite effective in suppressing vibrations due to a wide variety of disturbances, and performance of the modal controller can be significantly improved through knowledge-based tuning. Such a comprehensive investigation involving dynamics and controlled performance of a robotic system should prove useful in the design of this new class of manipulators. The study lays a sound foundation for further exploration of this class of novel manipulators.

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