| Summary: | 碩士 === 國立成功大學 === 機械工程學系 === 86 === Although parallel manipulators have many advantages in
applications, such as good precision and high rigidity, the
applications of parallelmanipulators are limited because of
their branching and singularity problem. To overcome these
problems, the motions of parallel manipulatorsmust be well-
planned, and there must be indices to indicate the occurrenceof
the singular configurations. In this thesis, the motion planning
of the three-degree-of-freedom planar parallel manipulator is
studied. Thegoal is to develop a scheme to guide the end-
effector from one positionto another without passing through any
singular configuration. First, we discuss the forward kinematics
of the planar parallel manipulator,including the branching
problem and the conditions of the occurrence of singularity. The
singularity is identified when the determinant of the
manipulator''s Jacobian matrix is zero. Second, a three-
dimensional illustrationof the singularity loci, named the
singularity surface, is developed. Third, the finite motion of
the end-effector is planned in the same space as that of the
singularity surface to guide the end-effector without
penetratingthe singularity surface. To overcome the branching
problem, the end-effector is guided by many via points. Finally,
we adjust the velocities of the joints to obtain smooth motions
at the via points. In this thesis, a C++ program is developed to
perform the motion planningof the manipulator. The motion is
then simulated in the software package Working Model to validate
the planned path. We have successfully planned the paths of the
end-effector of the manipulator to avoid branching and
singularity expect for the cases in which it is theoretically
impossible to achieve the goal.
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