Robotic Paint Repair Force Control Using Backup Pad Speed Feedback
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Solution Overview
Problem
Automating defect-specific repairs for paint applications in the automotive industry is challenging due to the inherent stiffness of robotic manipulators, which makes precise force control difficult, and existing systems require direct force measurement and frequent calibration, limiting their effectiveness and robustness.
Innovation Solution
The use of passive components like backup pads with aliasing marks and rotational velocity measurement via tachometers or encoders allows for indirect force control, eliminating the need for direct force measurement and reducing system stiffness, enabling more robust and resilient force control across various abrasive-substrate combinations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If robotic manipulators are used for paint repair, then automation is achieved, but precise force control becomes difficult due to inherent system stiffness
Solution Approach 1:
A compliant intermediary device is introduced between the robotic manipulator and the abrading tool. This compliant mechanism acts as a mediator that decouples the stiff robotic system from the force-sensitive abrading process, enabling precise force control through compliance while maintaining automation.
Solution Approach 2:
The system changes the mechanical parameter of stiffness by introducing compliance into the force path. By transforming the stiff robotic manipulator into a compliant force control system through the intermediary device, the system can precisely control applied forces during abrading while maintaining automation.
2Manufacturing precision
If direct force measurement is implemented, then force control is achieved, but system complexity and calibration requirements increase
Solution Approach 1:
The system replaces direct mechanical force measurement with an indirect optical measurement approach. By using a tachometer to measure rotational velocity of the backup pad and converting this to force information, the system avoids complex direct force sensors and their calibration requirements while achieving force control.
Solution Approach 2:
Instead of directly measuring force, the system measures a correlated parameter (rotational velocity) that copies or reflects the force state. The tachometer measures rotational velocity which serves as a proxy for the force applied during abrading, simplifying the measurement system while maintaining control capability.
3Manufacturing precision
If compliant mechanisms are added to reduce stiffness, then force control improves, but device complexity increases
Solution Approach 1:
A compliant intermediary device is introduced between the robotic manipulator and the abrading tool. This compliant mechanism acts as a mediator that decouples the stiff robotic system from the force-sensitive abrading process, enabling precise force control through compliance while maintaining automation.
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 enables precise control of forces during robotic paint repair and polishing, improving process windows and reducing the need for a priori knowledge or periodic calibration, resulting in a more cost-effective and robust automation method.
Implementation Method 1
The method utilized by the inventors can use the rotational velocity of the backup pad (determined via a tachometer) as an input to a pressure controller
Data Source
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AI summary
A system for robotic paint repair that can include a consumable abrasive product configured to abrade a substrate, a tool configured to drive the consumable abrasive product to abrade, a backup pad configured to couple with the consumable abrasive product, a robotic device configured to manipulate the tool, a pressure regulating apparatus mountable to the robotic device and configured to apply a desired pressure to the consumable abrasive product, a sensor configured to measure at least one of a rotational velocity of the backup pad or a debris pattern from the substrate that results from abrading, and a pressure controller configured to control the pressure regulating apparatus to apply the desired pressure based upon the at least one of the measured rotational velocity of the backup pad or the measured debris pattern.