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Abstract: The
over-restriction of a parallel kinematic machine (PKM) is simplified and
through analysis the 1-differential and 2-differential kinematic
equation, the identified parameters among which there are strong
relationships are eliminated and it proves that the vertical tolerance
along z axis is approximately only related with the non-vertical
coefficient of the two columns, so that the parameter errors are
classified from the view of output errors. Based on the only
relationship of the z axis vertical tolerance, calibration of the PKM is
carried out by two steps through a simple scheme about relative position
measurement. The results show that in almost all workspace the accuracy
is improved to below ±0.04 mm and in partial workspace the accuracy to
below ±0.02 mm, so that the industrial requirement is satisfied. The
method based on relativity analysis can simplify the calibrating process
and identify parameters step by step. Then it gives a new way for PKM
calibration.
Key words: Parallel kinematic machine Relativity Calibration
Error compensation
CLC No: TG659
国家973重点基础研究基金(G1998030607)和国家自然科学基金(50305016)资助项目. Received 20040430,
received in revised form 20041010
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