Robot End Tool Metrology Using XY Scale Imaging
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Solution Overview
Problem
Existing robotic systems face limitations in achieving high accuracy and reliability for end tool position determination, particularly in SCARA robots, due to factors like encoder performance and mechanical stability, which can result in inadequate positioning precision across various orientations during operations.
Innovation Solution
The implementation of an end tool metrology position coordinates determination system that includes a camera, an XY scale, and a metrology position coordinate processing portion, allowing for precise determination of end tool position by imaging the XY scale and utilizing imageable features to calculate relative positions with higher accuracy than traditional position sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional position sensors (rotary encoders) are used to determine end tool position, then the system structure remains simple, but the positioning accuracy is limited to approximately 100 microns
Solution Approach 1:
An XY scale with known coordinates is introduced as an intermediary reference object. The camera captures images of this scale to determine end tool position indirectly through coordinate calculation, achieving sub-micron accuracy without directly modifying the robot's position sensing mechanism.
Solution Approach 2:
The mechanical position sensing system (rotary encoders) is supplemented by an optical measurement system (camera + XY scale). The optical system replaces the need for high-precision mechanical encoders, achieving superior accuracy through light-based coordinate detection rather than mechanical rotation sensing.
2Measurement precision
If calibration techniques are used to improve robot positioning accuracy, then positioning precision can be enhanced, but the calibration process requires significant time and multiple iterations
Solution Approach 1:
The XY scale is pre-calibrated with known coordinates before use. This preliminary preparation eliminates the need for time-consuming iterative calibration during robot operations. The system can directly use the pre-established coordinate reference for immediate high-precision positioning.
Solution Approach 2:
Instead of physically calibrating the robot through repeated positioning iterations, the system creates a digital copy of the reference frame through the XY scale with known coordinates. The camera captures this coordinate copy, allowing rapid position determination without physical recalibration.
3Measurement precision
If high-precision position determination is achieved through multiple cameras and complex imaging systems, then measurement accuracy improves, but the device complexity and cost increase significantly
Solution Approach 1:
The system extracts only the essential measurement function from complex multi-camera systems. By using a single camera with a structured XY scale, the patent isolates the core coordinate detection capability, eliminating unnecessary imaging components while maintaining high precision.
Solution Approach 2:
The system changes the measurement parameter from direct spatial positioning to coordinate-based measurement. By using the XY scale's known coordinates as a reference parameter, the system achieves high precision through mathematical calculation rather than complex optical geometry, simplifying the imaging requirements.
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 system enhances the accuracy of end tool position determination to beyond the robot's standard accuracy, particularly for vector components transverse or perpendicular to the scale imaging axis, improving reliability and precision in workpiece measurements and positioning control.
Implementation Method 1
a first camera...acquire a digital image of the XY scale
Data Source
AI summary
An end tool metrology position coordinates determination system is provided for use with a robot. A first accuracy level defined as a robot accuracy (e.g., for controlling and sensing an end tool position of an end tool that is mounted proximate to a distal end of a movable arm configuration of the robot) is based on using position sensors (e.g., encoders) included in the robot. The system includes the end tool, an imaging configuration, XY scale, image triggering portion and processing portion. One of the XY scale or imaging configuration is coupled to the end tool and the other is coupled to a stationary element (e.g., a frame located above the robot). The imaging configuration acquires an image of the XY scale, which is utilized to determine a relative position that is indicative of the end tool position, with an accuracy level that is better than the robot accuracy.