Autonomous Sanding Force Control for Variable-Compliance Workpieces
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Solution Overview
Problem
Existing automated finishing systems struggle to efficiently process workpieces with varying compliance characteristics, leading to potential damage from high target forces and reduced material removal rates from low target forces.
Innovation Solution
The system autonomously scans a workpiece, compiles images into a virtual model, and collects compliance data to define regions with similar compliance characteristics. It then assigns target forces to these regions based on their compliance ranges, adjusting forces in real-time during processing to maintain optimal material removal while preventing damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high target forces are applied during automated finishing, then material removal rate is improved, but workpiece damage occurs due to excessive force on compliant regions
Solution Approach 1:
The system divides the workpiece into multiple regions based on compliance characteristics and assigns different target forces to each region. Rigid regions receive higher target forces for faster material removal, while compliant regions receive lower target forces to prevent damage. This spatial variation in force application resolves the contradiction between productivity and damage prevention.
Solution Approach 2:
The system dynamically adjusts target forces during the finishing process based on real-time compliance measurements and deflection data. The control system modifies force parameters adaptively as the workpiece is processed, allowing optimization of material removal rate while preventing damage to compliant regions throughout the operation.
2Object-affected harmful factors
If low target forces are applied during automated finishing, then workpiece damage is prevented, but material removal rate decreases
Solution Approach 1:
Instead of applying uniformly low target forces across the entire workpiece, the system identifies rigid regions through compliance mapping and applies higher target forces specifically to those areas. This allows damage prevention in compliant regions while maintaining high productivity in rigid regions through localized force optimization.
Solution Approach 2:
The system changes the target force parameter based on the compliance characteristics of different workpiece regions. By mapping compliance and adjusting force parameters accordingly, the system achieves both damage prevention and maintained productivity through parameter adaptation rather than uniform force reduction.
3Ease of operation
If uniform target forces are applied across the entire workpiece, then system operation is simplified, but processing efficiency decreases due to conservative force settings for compliant regions
Solution Approach 1:
The system performs preliminary compliance mapping and region classification before the main finishing operation. By pre-defining regions with similar compliance characteristics and assigning appropriate target forces in advance, the system maintains operational simplicity while optimizing processing efficiency through pre-planned force differentiation.
Solution Approach 2:
The workpiece is segmented into distinct regions based on compliance characteristics, with each region assigned a specific target force level. This segmentation allows the control system to manage multiple force levels systematically through region-based control, maintaining ease of operation while improving overall processing efficiency compared to uniform force application.
4Manufacturing precision
If region-based compliance mapping is implemented, then processing precision is improved, but system complexity increases due to additional scanning and data processing requirements
Solution Approach 1:
The system uses a multi-functional end effector that combines compliance sensing, optical scanning, and finishing operations. By integrating multiple functions into a single tool, the system achieves region-based compliance mapping and precision processing without proportionally increasing system complexity, as the same hardware performs multiple measurement and processing tasks.
Solution Approach 2:
The system performs self-characterization by autonomously scanning the workpiece, mapping compliance regions, and generating processing parameters without external intervention. This self-service capability reduces the need for external measurement equipment and manual programming, offsetting the complexity of compliance mapping through automated data acquisition and processing.
Data Source
AI summary
One variation of a method includes: accessing a maximum deflection distance of a workpiece; defining a first workpiece region characterized by a first compliance range; defining a second workpiece region characterized by a second compliance range greater than the first compliance range; assigning a nominal target force to the workpiece; navigating a sanding head across the first workpiece region during a processing cycle; driving the sanding head below a virtual unloaded surface of the workpiece stored in the virtual model to maintain forces, of the sanding head on the first workpiece region, approximating the nominal target force; calculating a maximum offset between the positions of the sanding head in the first workpiece region and the virtual unloaded surface; and, in response to the first maximum offset approaching the maximum deflection distance, assigning a lower target force to the second workpiece region of the workpiece.