Type Synthesis and Analysis  of  Parallel  Manipulators  with  Multiple Operation Modes

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Khodakhani, Saeed | 2011

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Type of Document: M.Sc. Thesis
Language: Farsi
Document No: 42003 (08)
University: Sharif University of Technology
Department: Mechanical Engineering
Advisor(s): Zohoor, Hassan; Sohrabpoor, Saeed
Abstract:
Two robots with same number of degrees of freedom (DOF) may have different motion patterns. Planar, spherical and translational motions are typical 3 DOF motions. So far, many studies in the field of less than 6 DOF mechanisms have been focused on synthesis and development of parallel mechanisms (PM) with a specific motion pattern. Recent investigations show that there is possibly new type of PMs that could change their operation modes and satisfy more than one motion pattern. For applications in which the platform should undergo one motion pattern at part of workspace and a different motion pattern in some other poses, utilizing these PMs instead of a 6 DOF robot obviously reduces number of required actuators. This study intends to find new mechanisms with multiple operation modes in a systematic manner. After proposing a comprehensive method based on screw theory and geometrical constraint analysis, synthesis of all 3 DOF PMs with more than one operation mode is accomplished. In addition, to control both ordinary and acquired degrees of freedom at transitional singular poses, proper selection of actuated joints is considered
Keywords:
Screw Theory ; Kinematics Analysis ; Parallel Mechanism ; Type Synthesis ; Mobility Analysis

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