Robot-Guided Self-Piercing Riveting Pose Compensation
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Solution Overview
Problem
Robot-assisted punch riveting processes face challenges due to high process forces causing elastic deformations in riveting tools, which affect the riveting results, and the need for lighter tools with longer legs complicates the process.
Innovation Solution
The method involves adjusting the pose of the self-piercing riveting tool during the riveting process using a robot to compensate for elastic deformations, utilizing a deformation model to guide the tool's movement and correct for bending or displacement, allowing for lighter and longer tool designs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high process forces are applied during punch riveting, then the riveting strength is improved, but elastic deformations of the tool occur which impair riveting results
Solution Approach 1:
The robot applies a preliminary counteracting movement to the riveting tool before the actual riveting operation. Based on a deformation model that predicts tool deformation under riveting forces, the robot positions the tool in advance to compensate for expected elastic deformation, ensuring the tool maintains its correct pose during high-force riveting without compromising precision
Solution Approach 2:
The system uses a deformation model that incorporates feedback from measured or calculated tool deformations under riveting forces. This model allows the robot controller to adjust the tool pose dynamically during the riveting process, counteracting elastic deformations in real-time and maintaining manufacturing precision despite high process forces
2Weight of moving object
If the riveting tool is designed to be lighter, then the robot payload is reduced, but the tool becomes more susceptible to elastic deformations under high process forces
Solution Approach 1:
The system preemptively adjusts the tool pose to counteract expected elastic deformations. By using a deformation model to predict how a lightweight tool will deform under riveting forces, the robot positions the tool in advance to compensate, allowing lightweight tools to maintain positioning accuracy without requiring heavy construction
Solution Approach 2:
The system dynamically changes the pose parameters of the riveting tool during operation based on the deformation model. This allows the tool to adapt its position and orientation to compensate for elastic deformations, enabling lightweight tool design while maintaining manufacturing precision through real-time parameter adjustment
3Length of moving object
If longer legs are used in the riveting tool, then rivets can be set farther from component edges, but the tool becomes more prone to elastic deformations
Solution Approach 1:
The robot applies a preliminary counteracting movement to the tool legs before riveting operations. The deformation model predicts the elastic deformation of long legs under riveting forces, and the robot positions the tool in advance to compensate, allowing long-legged tools to reach distant rivet locations while maintaining positioning accuracy
Solution Approach 2:
The system makes the tool pose dynamic rather than static. The robot continuously adjusts the tool position and orientation during operation based on the deformation model, allowing long legs to flex and deform elastically while the robot compensates in real-time, maintaining manufacturing precision despite the increased length and susceptibility to deformation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach improves the precision and accuracy of the riveting process by partially compensating for tool deformations, enhancing the riveting results and maintaining tool integrity.
Implementation Method 1
high process forces, frequently in the range of, sometimes significantly, over 20 kN. This can lead to elastic deformations, even with robust punch riveting tools
Data Source
Figure 1~5
Figure 3~6
AI summary
A method for positioning a self-piercing-rivet setting tool (20) by means of a robot (10) comprises the steps of: commanding (S120) a robot (10) to position a self-piercing-rivet setting tool (20) in a riveting pose at at least two workpieces (40, 41) to be joined together; and commanding (S130) the self-piercing-rivet setting tool to set a rivet (3) to join the at least two workpieces by means of self-piercing riveting; wherein, during said self-piercing riveting, the robot is commanded to change the pose of the self-piercing-rivet setting tool to at least partially compensate for an elastic deformation, induced by the self-piercing rivet, of the self-piercing-rivet setting tool, and/or the steps of: commanding (S10) the robot to position the self-piercing-rivet setting tool in a riveting pose; commanding (S20) a self-piercing-rivet movement of the self-piercing-rivet setting tool with or without setting of a rivet; and manually or sensor-based, in particular automatically, detecting (S30) a change in pose of a die of the self-piercing-rivet setting tool or of a test element as a result of the self-piercing-rivet movement; the self-piercing-rivet setting tool being checked (S40) and/or a deformation model being calibrated (S100) on the basis of the detected change in pose.