Algorithm and experiments of six-dimensional force/torque dynamic measurements based on a Stewart platform

详细信息    查看全文

• 作者：Ke Wen^a ; ^{rongyu_wen@163.com} ; Fuzhou Du^a ; ^{du_fuzhou@163.com}Author Vitae ; Xianzhi Zhang^b ; ^{X.Zhang@kingston.ac.uk}
• 关键词：Dynamic gravity compensation ; F/T-driven alignment ; Precision analysis ; P&O adjusting platform ; Six-dimensional F/T
• 刊名：Chinese Journal of Aeronautics
• 出版年：2016
• 出版时间：December 2016
• 年：2016
• 卷：29
• 期：6
• 页码：1840-1851
• 全文大小：2955 K
• 卷排序：29

文摘

Stewart platform (SP) is a promising choice for large component alignment, and interactive force measurements are a novel and significant approach for high-precision assemblies. The designed position and orientation (P&O) adjusting platform, based on an SP for force/torque-driven (F/T-driven) alignment, can dynamically measure interactive forces. This paper presents an analytical algorithm of measuring six-dimensional F/T based on the screw theory for accurate determination of external forces during alignment. Dynamic gravity deviations were taken into consideration and a compensation model was developed. The P&O number was optimized as well. Given the specific appearance of repeated six-dimensional F/T measurements, an approximate cone shape was used for spatial precision analysis. The magnitudes and directions of measured F/Ts can be evaluated by a set of standards, in terms of accuracy and repeatability. Experiments were also performed using a known applied load, and the proposed analytical algorithm was able to accurately predict the F/T. A comparison between precision analysis experiments with or without assembly fixtures was performed. Experimental results show that the measurement accuracy varies under different P&O sets and higher loads lead to poorer accuracy of dynamic gravity compensation. In addition, the preferable operation range has been discussed for high-precision assemblies with smaller deviations.