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Abstract: Absolute coordinates of spherical joints on movable
platform are chosen as unknowns ,a direct displacement analysis which is
based on resultant eliminatiom method for a 4-DOF spatial parallel
mechanism is presented, 7 degrees input-output closed form equation with
one unknown is obtained, and all of the roots for all unknowns are
gained. Numeric-symbolic technique is introduced in the procedure of
resultant elimination, procedure of number-symbol manipulation is
transformed into that of matrix manipulation. Because joint variables are
treated as symbols and all structure parameters are treated as real
numbers, the complexity of derivation for input-output equation is
reduced. The solution is verified with a numerical example, its results
without extraneous roots agree with the original equations.
Key words: Parallel mechanism Direct displacement solution Resultant
elimination Numeric-symbolic approach
CLC No: TP242
Received 20010702, received in revised form 20020402
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