Robotic Drill Head Re-Centering After Template Hole Binding
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Solution Overview
Problem
Robotic drilling systems face challenges in achieving accurate alignment between a drill head and a hole in a drill template due to metrology errors and positional inaccuracies, especially in mobile systems, which can lead to binding issues and require expensive infrastructure for precise localization.
Innovation Solution
A robotic drill system equipped with a tool head featuring an expandable collet and sensors that detect binding, allowing for self-centering to correct alignment by expanding to fit snugly within the hole, enabling precise placement of the end effector using a combination of robotic actuators and sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If laser scanners are used to precisely locate surface features, then measurement precision is improved, but productivity deteriorates due to slow scanning speed
Solution Approach 1:
The system performs preliminary localization using a vision system to identify hole locations before drilling, and uses preliminary binding detection during insertion to trigger self-centering actions. This preliminary action approach allows the use of faster but less precise vision systems instead of slow laser scanners, while still achieving accurate positioning through the self-centering mechanism.
2Manufacturing precision
If larger and more expensive robots are used to increase system stiffness, then manufacturing precision is improved, but device complexity and cost increase
Solution Approach 1:
The drill template's hole structure serves the dual function of guiding the tool head insertion and automatically centering it through the binding-detect-and-self-center mechanism. The system uses its own structural features (the hole and expandable collet) to correct positioning errors, eliminating the need for external high-precision positioning infrastructure or larger, stiffer robots.
Solution Approach 2:
The expandable collet changes its diameter parameter dynamically - starting with a smaller diameter for initial insertion, then expanding to a larger diameter for precise centering and drilling. This parameter change allows the same component to perform both insertion and precise positioning functions, achieving high manufacturing precision without requiring a larger, more complex robotic system.
3Ease of operation
If the retracted diameter of the expandable collet is made smaller to facilitate insertion, then ease of operation is improved, but manufacturing precision deteriorates due to increased clearance
Solution Approach 1:
The collet diameter is made dynamic rather than static - it starts small for easy insertion, then expands automatically upon detecting binding. This dynamic parameter allows the system to optimize for both insertion ease (small initial diameter) and centering precision (expanded diameter with wall contact), resolving the contradiction between these two requirements.
Data Source
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AI summary
A robotic drill system and a method of drilling with a robotic drill system. This includes inserting a tool head of the robotic drill within a hole of a drill template along an initial insertion trajectory with a robotic manipulator arm that is moved by at least one robotic actuator for causing robotic insertion of the tool head. In response to sensing binding of the tool head to a wall of the hole while inserting the tool head along the initial insertion trajectory, the disclosure includes stopping robotic insertion of the tool head and activating a self-centering device of the tool head to reorient the tool head to a corrected alignment of the tool head axis relative to the hole. The self-centering device may include an expandable collet.