Assembly precision design for parallel robotic mechanism based on uncertain hybrid tolerance allocation
Robotic Intelligence and Automation
ISSN: 2754-6969
Article publication date: 10 February 2023
Issue publication date: 28 March 2023
Abstract
Purpose
The coupling impact of hybrid uncertain errors on the machine precision is complex, as a result of which the designing method with multiple independent error sources under uncertainties remains a challenge. For the purpose of precision improvement, this paper focuses on the robot design and aims to present an assembly precision design method based on uncertain hybrid tolerance allocation (UHTA), to improve the positioning precision of the mechanized robot, as well as realize high precision positioning within the workspace.
Design/methodology/approach
The fundamentals of the parallel mechanism are introduced first to implement concept design of a 3-R(4S) &3-SS parallel robot. The kinematic modeling of the robot is carried out, and the performance indexes of the robot are calculated via Jacobian matrix, on the basis of which, the 3D spatial overall workspace can be quantified and visualized, under the constraints of limited rod, to avoid the singular position. The error of the robot is described, and a probabilistic error model is hereby developed to classify the hybrid error sensitivity of each independent uncertain error source by Monte Carlo stochastic method. Most innovatively, a methodology called UHTA is proposed to optimize the robot precision, and the tolerance allocation approach is conducted to reduce the overall error amplitude and improve the robotized positioning precision, on the premise of not increasing assembly cost.
Findings
The proposed approach is validated by digital simulation of medical puncture robot. The experiment highlights the mathematical findings that the horizontal plane positioning error of the parallel robotic mechanism can be effectively reduced after using UHTA, and the average precision can be improved by up to 39.54%.
Originality/value
The originality lies in UHTA-based precision design method for parallel robots. The proposed method has widely expanding application scenarios in industrial robots, biomedical robots and other assembly automation fields.
Keywords
Acknowledgements
The work presented in this article is funded by the National Natural Science Foundation of China (51935009; 51821093); Zhejiang University president special fund financed by Zhejiang province (2021XZZX008); Zhejiang provincial key research and development project of China (LGG21E050020); The Ng Teng Fong Charitable Foundation in the form of ZJU-SUTD IDEA Grant (188170–11102).
Citation
Xu, J., Tao, M., Gao, M., Zhang, S., Tan, J., Xu, J. and Wang, K. (2023), "Assembly precision design for parallel robotic mechanism based on uncertain hybrid tolerance allocation", Robotic Intelligence and Automation, Vol. 43 No. 1, pp. 23-34. https://doi.org/10.1108/RIA-10-2022-0254
Publisher
:Emerald Publishing Limited
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