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Browsing by Subject "mu-Tip"

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    Dynamic Modeling and Passivity-Based Control of a 2 DOF Tower Crane with a Flexible Hoist Cable
    (2020-08) Shen, Ping-Yen
    Tower cranes are ubiquitous with the construction of modern infrastructure owing to high payload capacity, operational flexibility, and efficiency. This thesis aims to find a solution to achieving quick payload maneuver trajectory with reduced oscillations, and ensuring applicability to autonomous tower cranes that feature noncolocation, underactuation, and uncertain dynamics. A dynamic model of a 2 DOF tower crane is presented accounting for the winch inertia and the axial cable stiffness that varies with the length of the cable using a Rayleigh-Ritz discretization approach. The two proposed control methods, mu-tip control and adaptive sliding-mode control, employ passivity-based control to provide rigorous robust guarantees of closed-loop input-output stability when performing trajectory tracking of a tower crane's payload. The use of the mu-tip rate for trajectory tracking of the crane's payload greatly simplifies the task of designing a stabilizing feedback controller. The proposed mu-tip control uses a mu-tip modification to establish a passive input-output mapping of a 2 DOF tower crane with a flexible hoist cable from a modified force input to the payload's mu-tip rate by considering the sway angle as a flexible coordinate. However, the mu-tip control method relies on the assumptions that the sway angle and its angular rate remain small. A robust sliding-mode-inspired passivity-based control with an adaptive update law that does not rely on a specific structure of the dynamic equations or exact knowledge of the crane's mass properties is presented including experimental validations. A formulation of the adaptive sliding-mode control in the payload coordinates, which facilitates the generation of desired trajectories and the choice of control gains, is presented. The control theory developed in this thesis is not limited to only tower cranes, and can be extended to cable-driven robots and flexible robotic manipulators.