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Abstract: Based
on the inverse kinematics equations, some general results on the
velocities and accelerations of wires used for motion trajectory
planning of 6-DOF wire-driven PKMs have been addressed, which show that
the value of the velocity of a wire is always less or equal to the value
of velocity of the respective moving platform attachment point, and the
value of a plus wire acceleration is always not greater than the
projection of the respective attachment point acceleration on the tensio
direction. A criterion almost suitable for any trajectory in the
workspace to calculate the tension of wires is used. A 6-DOF CRPM C
Completely restrained positioning mechanism with a compact size has been
introduced to demonstrate the kinematic characteristics of wires with
the objective that spatial helical shaped trajectory can be realized by
the endeffector. The results of trajectory planning are obtained to
illustrate the velocities, accelerations and tensions of wires, and
prove the correctness of the general results obtained; and moreover, the
tension of some wires changes slightly, however, the tension of the
other wires changes greatly. The results offer some data for further
motion scheme control of this manipulator. Also, the method of motion
trajectory planning proposed is applicable for general 6-DOF wire-driven
PKMs.
Key
words: Wire-driven
PKM 6-DOF Motion trajectory planning
CLC No: TH112
Received 20040207, received in revised form
20020040515
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