Digital Twin Alignment for Force-Controlled Workpiece Finishing
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Solution Overview
Problem
Existing automated finishing systems face challenges in generating accurate digital twins of workpieces due to low-resolution optical data and unpredictable compliance characteristics, leading to errors in material removal and surface finish.
Innovation Solution
An autonomous scanning and sanding system that captures sparse optical data, transforms it into a low-resolution virtual model, and corrects it in real-time using force feedback to maintain target forces, adjusting for compliance and deformations during processing to create a high-accuracy digital twin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If sparse optical data is captured to reduce measurement time, then productivity is improved, but measurement precision deteriorates
Solution Approach 1:
The patent replaces optical measurement systems with force sensor-based mechanical measurement. Force sensors mounted on the sanding head directly measure contact forces between the sanding head and workpiece, providing high-precision dimensional data without requiring extensive optical scanning. This substitution enables accurate digital twin generation while maintaining fast processing speeds.
2Measurement precision
If high-resolution optical scanning is performed to improve measurement precision, then measurement precision is improved, but productivity deteriorates
Solution Approach 1:
The patent extracts only the essential dimensional information needed for finishing operations by using force sensor measurements during actual sanding contact. Instead of performing comprehensive high-resolution optical scanning of the entire workpiece, the system measures only the contact points and forces relevant to material removal, significantly reducing scan time while maintaining sufficient precision for the application.
3Device complexity
If compliance characteristics are not accounted for in the virtual model, then device complexity is reduced, but manufacturing precision deteriorates
Solution Approach 1:
The patent implements feedback loops where force sensor measurements during sanding operations are continuously fed back to update the digital twin model. The system measures actual contact forces, compares them with predicted forces from the virtual model, and adjusts the compliance characteristics of the workpiece model accordingly. This iterative feedback process accurately captures compliance without requiring complex initial modeling assumptions.
4Ease of operation
If the sanding head follows a predetermined toolpath without adjustment, then ease of operation is improved, but manufacturing precision deteriorates due to compliance variations
Solution Approach 1:
The patent transforms the static predetermined toolpath into a dynamic adaptive toolpath that adjusts in real-time based on force sensor feedback. The system continuously monitors contact forces during sanding operations and modifies the toolpath parameters (such as sanding head position, speed, and pressure) to compensate for workpiece compliance variations. This dynamic adjustment maintains manufacturing precision while preserving the simplicity of automated toolpath execution.
Data Source
AI summary
A method includes: compiling images, captured by an end effector traversing a scan path over a workpiece, into a virtual model of the workpiece; generating a toolpath based on a geometry of the workpiece represented in the virtual model; and assigning a target force to the workpiece. The method also includes, during a processing cycle: navigating a sanding head, arranged on the end effector, across the workpiece according to the toolpath; based on force values output by a force sensor coupled to the sanding head, deviating the sanding head from the toolpath to maintain forces of the sanding head on the workpiece proximal the target force; and tracking a sequence of positions of a reference point on the sanding head, traversing the workpiece, in contact with the workpiece. The method also includes transforming the virtual model into alignment with the sequence of positions of the reference point.