Servo-Driven Robot Drill Clamp for Accurate Workpiece Positioning
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Solution Overview
Problem
Robotic drilling in high precision applications, such as aerospace, faces positional and orientation accuracy issues due to kinematic, compliance, and backlash errors, and existing clamps can cause inaccuracies and damage to workpieces with high clamping pressures.
Innovation Solution
A servo motor-driven clamp with a force sensor and a non-slip surface for the robotic drill, allowing controlled clamping force application and precise positioning, combined with a metrology system for bias determination and offset correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pneumatic clamp applies high pressure to hold the drilling tool against the workpiece, then the tool is secured in position, but the workpiece positioning accuracy deteriorates and the workpiece may be damaged
Solution Approach 1:
The clamp uses a servo motor to dynamically adjust and control the clamping force parameter, applying only the necessary amount of force to secure the tool without exceeding what would cause workpiece damage or positioning error. This replaces the conventional pneumatic high-pressure approach with a controlled, measurable, and adjustable mechanical force.
Solution Approach 2:
The invention replaces the pneumatic actuation system with a servo motor-driven mechanical system. This substitution allows for precise control of clamping force through servo control, eliminating the uncontrolled high pressure inherent in pneumatic systems while maintaining reliable tool holding.
2Measurement precision
If a robotic arm uses internal encoders for feedback to achieve positioning accuracy, then reasonable precision is obtained, but kinematic errors, compliance errors, and backlash errors still reduce overall accuracy
Solution Approach 1:
The clamp incorporates a force sensor that provides real-time feedback on the clamping force applied to the workpiece. This feedback loop allows the servo motor to adjust the clamping force dynamically, ensuring optimal positioning accuracy by compensating for variations in workpiece compliance and preventing excessive force that would cause positioning errors.
Solution Approach 2:
The invention isolates the clamping function from the robotic arm's positioning system. By providing a separate, actively controlled clamping mechanism with its own servo motor and force sensor, the system segments the positioning control from the tool holding function, allowing each to be optimized independently and compensating for the robotic arm's inherent errors.
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
The solution significantly reduces positioning errors and maintains accuracy by applying controlled clamping forces and using bias corrections, enhancing the precision and repeatability of robotic drilling operations.
Implementation Method 1
a force sensor arranged to measure a force acting on the workpiece contacting portion in the drilling direction
Implementation Method 2
an actuation mechanism comprising a servo motor configured to drive linear movement of the frame relative to the drilling tool
Implementation Method 3
a non-slip surface for contacting a surface of a workpiece to be drilled
Data Source
Figure 1~1c
Figure 2
Figure 3
AI summary
The invention relates to a clamp for a robotic drill, and to a related method and system for robotic drilling of a component. Example embodiments include a clamp (200) configured for attachment to a drilling tool (201) of a robotic drill, the clamp (200) comprising: an attachment portion (220) configured for attachment to the drilling tool (201); a frame (202) linearly moveable relative to the attachment portion (220) along a central axis (203) of the clamp (200) parallel to a drilling direction of the drilling tool (201); an actuation mechanism comprising a servo motor (205) configured to drive linear movement of the frame (202) relative to the drilling tool (201); a workpiece contacting portion (206) at a distal end (207) of the frame (202), comprising a surface (208) for contacting a surface of a workpiece to be drilled and an aperture (209) allowing for passage of a drill bit (204) of the drilling tool (201) through to the workpiece surface; and a force sensor (210) arranged to measure a force acting on the workpiece contacting portion (206) in the drilling direction (221).