Autonomous Sanding Force Control for Variable-Compliance Workpieces
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Solution Overview
Problem
Automated finishing systems face challenges in efficiently processing workpieces with varying compliance characteristics, as high target forces can damage compliant regions while low forces result in slow material removal and inconsistent contact, leading to poor surface finish and extended processing times.
Innovation Solution
A method that autonomously scans a workpiece to create a virtual model, identifies regions with different compliance characteristics, and adjusts the target force in real-time based on compliance ranges, using a sanding head with a force sensor and optical sensors to navigate and maintain optimal force levels across varying surface types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high target forces are applied during automated finishing, then material removal efficiency is improved, but compliant regions of the workpiece are damaged
Solution Approach 1:
The system applies different target forces to different regions of the workpiece based on their compliance characteristics. The compliance map divides the workpiece into regions with varying compliance levels, and the controller adjusts the target force accordingly - higher forces for rigid regions to maximize material removal, and lower forces for compliant regions to prevent damage.
Solution Approach 2:
The target force is not static but dynamically adjusted during the finishing process. The controller continuously modifies the target force based on the compliance map data, transitioning between different force levels as the finishing tool moves across regions with varying compliance characteristics.
2Object-affected harmful factors
If low target forces are applied during automated finishing, then compliant regions are protected, but material removal rate decreases and processing time increases
Solution Approach 1:
Instead of applying a uniformly low target force across the entire workpiece, the system applies low forces only to compliant regions while maintaining higher forces on rigid regions. This localized approach protects vulnerable areas without sacrificing overall productivity.
Solution Approach 2:
The workpiece is segmented into multiple compliance-based regions through the compliance map. This segmentation allows the system to treat different regions differently, applying appropriate force levels to each segment rather than using a single force level for the entire workpiece.
3Ease of operation
If uniform target force is applied across the workpiece, then the system is simple to operate, but surface finish consistency deteriorates on workpieces with varying compliance
Solution Approach 1:
The compliance map is generated in advance before the finishing operation begins. This preliminary characterization of workpiece compliance allows the controller to pre-calculate appropriate target forces for each region, eliminating the need for complex real-time adjustments during processing while ensuring consistent surface finish.
Solution Approach 2:
The system creates a digital compliance map that replicates the physical workpiece's compliance characteristics. This virtual model allows the controller to plan and optimize the finishing process based on accurate representations of workpiece properties without requiring physical trial and error.
4Device complexity
If compliance characteristics are manually assessed, then equipment complexity is reduced, but measurement precision and reliability of compliance data decrease
Solution Approach 1:
The system replaces manual mechanical assessment of compliance with automated sensing technology. Force sensors and displacement sensors objectively measure compliance characteristics, eliminating the subjectivity and variability inherent in manual assessment while providing precise, quantifiable data for process control.
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.