Study of the Ultimate Error of the Axis Tolerance Feature and Its Pose Decoupling Based on an Area Coordinate System

The assembly process is sometimes blocked due to excessive dimension deviations during large-scale assembly. It is inefficient to improve the assembly quality by trial assembly, inspection, and accuracy compensation in the case of excessive deviations. Therefore, assemblability prediction by analyzing the measurement data, assembly accuracy requirements, and the pose of parts is an effective way to discover the assembly deviations in advance for measurement-assisted assembly. In this paper, a coordination space model is constructed based on a small displacement torsor and assembly accuracy requirements. An assemblability analysis method is proposed to check whether the assembly can be executed directly. Aiming at the incoordination problem, an assemblability optimization method based on the union coordination space is proposed. Finally, taking the space manipulator assembly as an example, the result shows that the proposed method can improve assemblability with a better assembly quality and less workload compared to the least-squares method.

Section: Space Manipulator Assemblymentioning

confidence: 99%

“…Ma et al [12] developed the assembly precision pre-analysis technique in the simulation of virtual assembly. Du et al [13] proposed a pose decoupling model of the axis tolerance feature to decouple the analysis of any pose within the tolerance domain.…”

Section: Introductionmentioning

confidence: 99%

A Coordination Space Model for Assemblability Analysis and Optimization during Measurement-Assisted Large-Scale Assembly

Cui

2020

“…Louhichi [5] proposed the discrete method to model the geometrical tolerances, all the possible translation and rotation errors are sampled by the displacements of the ideal feature. Du [6] developed the pose decoupling method for the shaft-hole fit, and studied all the possible pose of the axis within the tolerance domain.…”

Section: Introductionmentioning

confidence: 99%

Tolerance Modeling and Analysis Considering Form Defects for Spaceborne Array Antenna

Liu

Qiu

et al. 2020

Tolerance analysis is becoming increasingly important for tolerance design and optimization. When dealing with electromechanical products such as the array antenna, the form errors of the assembly must be considered. Traditional tolerance analysis with form errors relies on a double loop process, which is computationally expensive. A new tolerance analysis method is proposed in this paper, which can be achieved by a single loop process. First, a new tolerance modeling method considering form errors was proposed, it can represent the geometric error of a surface feature precisely. Then an effective sampling method was developed by introducing the variance separation method. An assembly simulation method was proposed to determine the final state of the whole assembly. Finally, the tolerance analysis was achieved based on the sufficient sample. The proposed analysis method was applied to an X-band spaceborne active-phased array antenna, numerical simulation results show the effectiveness of the method.

“…The SDT model uses screws and constraints to establish the extreme limits of part tolerance zones [15][16][17]. To overcome the lack of analytical models between the target feature and each feature on the dimensional chain, HTM was combined with T-Map to obtain an expression of the decoupling pose of tolerance features [18]. Since the Jacobian matrices are quite suitable for deviation propagation [19], the unified Jacobian-Torsor model was developed for product precision performance estimation [20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Assembly Tolerance Design Based on Skin Model Shapes Considering Processing Feature Degradation

Zhang

Qiu

et al. 2019

To increase the reliability and accuracy of tolerance design, more and more research works are considering not only orientation and position deviations; they are also forming errors in tolerance modeling. As a direct cause of form errors in industrial mass production, the processing features of the machining system degrade over time. Under the Industry 4.0 paradigm, an assembly tolerance design method based on Skin Model Shape is proposed to take the effect of degrading processing features into consideration. A continuous-time multi-dimensional Markov process is trained through maximum likelihood estimation based on the nodal sampling point set on the machined surface. Degradation of the machined surface is modeled based on the joint probability distribution of nodal displacements. Assembly force constraints and assembly entity constraints are applied to spatial assembly simulations. Tolerance synthesis takes the manufacturing cost and assembling probability as design objectives. A design example of the rotary feed component in a five-axis machine tool is proposed for explanation and verification.