Browsing by Author "Clinton, Charles M."
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Item Dynamic Variation of the Workspace of an Octahedral Hexapod Machine Tool During Machining(1997) Conti, Joseph P.; Clinton, Charles M.; Zhang, Guangming; Wavering, Albert J.; ISRA method is presented to evaluate the workspace variation of a Stewart platform based machine tool. Four sets of constraints, covering strut lengths, platform spherical joint angles, base spherical joint angles, and strut collisions, are formulated using inverse kinematics. Recognizing the need for varying the platform orientation during machining, an algorithm to efficiently calculate the workspace is developed. Computer implementation provides a powerful tool to study the dynamic variation of the workspace as the spindle platform rotates away from the horizontal orientation. A case study is presented on the workspace variation of an Ingersoll Octahedral Hexapod machine tool during machining. The results demonstrate the shift in size and location of the workspace as the platform orientation changes. Guidelines for NC coding are suggested to maximize the versatility of Stewart platform based machine tools, while avoiding the violation of constraint conditions on the workspace.Item Stiffness Modeling of a Stewart Platform Based Milling Machine"(1997) Clinton, Charles M.; Zhang, Guangming; Wavering, Albert J.; ISRThis paper presents the development of a mathematical model describing the stiffness of a Stewart-platform-based milling machine. Matrix structural analysis is used to derive the stiffness matrix for each of the elements in the model and assemble them into a system-wide stiffness matrix. By incorporating the inverse kinematics of the machine tool, the system model is used to visualize the stiffness variation over the mill's workspace. Estimation of the system parameters is conducted through experimental stiffness measurements. Computer simulation is used to demonstrate how the developed stiffness model suggests an optimization process for tool-path planning.