Supplementary Metrology for Articulated Robot End Tool Positioning
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Solution Overview
Problem
Existing SCARA robot systems face limitations in positioning accuracy, particularly for end tool positioning, which can be time-consuming to calibrate and may not provide desired levels of reliability, repeatability, and speed, especially for all orientations during operations.
Innovation Solution
A robot system incorporating an articulated robot with a supplementary metrology position coordinates determination system, which includes a camera and an XY scale, allows for improved accuracy in determining end tool position by using image processing to identify features on the XY scale and calculate relative positions, offering better than robot accuracy for x and y coordinates in the x-y plane.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional robot position sensors (rotary encoders) are used for end tool positioning, then the system is simple and easy to operate, but the positioning accuracy is limited to approximately 100 microns
Solution Approach 1:
The patent introduces an XY scale as an intermediary measurement device that provides high-precision reference markings. The camera captures images of these markings to determine end tool position with accuracy better than 100 microns, while the robot system continues to use its simple rotary encoder sensors for basic control. This intermediary measurement system resolves the contradiction by providing high precision without requiring the entire robot system to become complex.
Solution Approach 2:
The patent replaces the mechanical position sensing approach (rotary encoders with 100 micron accuracy) with an optical measurement system (camera capturing XY scale markings). This substitution achieves superior positioning accuracy by using optical image processing instead of mechanical encoder readings, directly addressing the accuracy limitation while maintaining system simplicity through modular integration.
2Measurement precision
If calibration techniques are used to improve robot positioning accuracy, then measurement precision improves, but the calibration process is time-consuming and may not provide desired reliability for all orientations
Solution Approach 1:
The XY scale is pre-calibrated with known marking positions before use, establishing a reference framework in advance. During operation, the camera simply captures images of these pre-positioned markings to determine end tool location, eliminating the need for time-consuming calibration procedures during each operation cycle. This preliminary setup provides reliable accuracy for all orientations without repeated calibration time investment.
3Productivity
If traditional robot systems are used for workpiece measurement and inspection, then the system is simple to operate, but the speed and reliability of position determination are insufficient
Solution Approach 1:
The patent implements a feedback mechanism where the camera continuously captures images of the XY scale markings, and the processing system calculates end tool position based on these real-time images. This optical feedback loop provides both high speed (instantaneous image capture and processing) and high reliability (repeatable marking recognition), resolving the contradiction by providing rapid and consistent position determination without compromising system simplicity.
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 system enhances the accuracy of end tool positioning beyond traditional robot accuracy, enabling more precise control and faster operations by integrating image processing and metrology position coordinates, thus improving reliability and repeatability.
Implementation Method 1
a first camera...acquire a digital image of the XY scale
Implementation Method 2
image processing to identify features on the XY scale and calculate relative positions
Data Source
AI summary
A supplementary metrology position coordinates determination system is provided for use with an articulated 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 coupled to a robot arm portion that moves in an XY plane), is based on using position sensors (e.g., rotary encoders) included in the robot. The supplementary system includes an imaging configuration, XY scale, image triggering portion and processing portion. One of the XY scale or imaging configuration is coupled to the robot arm portion 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.