Supplementary Metrology for Robot End Tool Positioning
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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 orientations where traditional calibration techniques are time-consuming and do not provide the desired level of precision for workpiece measurements and other processes.
Innovation Solution
A supplementary metrology position coordinates determination system that includes a first imaging configuration, an XY scale, an image triggering portion, and a metrology position coordinate processing portion, which uses a camera and incremental or absolute scale features to determine the end tool position with higher accuracy than traditional position sensors, especially for vector components transverse or perpendicular to the scale imaging axis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional position sensors (rotary encoders) are used for end tool position determination, then the system is simple and cost-effective, 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 scale acts as a mediator between the robot system and the measurement objective, enabling sub-micron accuracy without requiring complex modifications to the robot's core positioning mechanism. The scale's precise graduations serve as a reference framework that enhances measurement capability.
Solution Approach 2:
The patent replaces traditional mechanical position sensing (rotary encoders with 100 micron accuracy) with an optical measurement system. By using a camera to capture images of the XY scale and processing these images computationally, the system achieves sub-micron accuracy, substituting mechanical sensing with optical and computational methods.
2Measurement precision
If calibration techniques are used to improve robot positioning accuracy, then measurement precision can be enhanced, but the calibration process is time-consuming and does not provide desired precision for all orientations
Solution Approach 1:
The XY scale is pre-calibrated with known graduation positions and reference markings before use. This preliminary preparation of the measurement reference allows the system to achieve high accuracy immediately upon installation, eliminating the need for time-consuming calibration procedures for each robot orientation. The pre-established reference framework enables direct measurement without iterative calibration.
3Measurement precision
If laser trackers or photogrammetry are used to achieve high accuracy, then measurement precision improves, but the equipment is expensive and occupies work volume
Solution Approach 1:
The patent uses a camera to create optical copies (images) of the XY scale graduations. By capturing and processing these optical copies computationally, the system achieves high measurement accuracy without requiring expensive laser trackers or complex photogrammetry equipment. The digital image processing of the scale markings provides a cost-effective alternative to sophisticated optical measurement systems.
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 provides improved accuracy and reliability for end tool position determination, enhancing the precision of workpiece measurements and positioning control, while being more efficient and less expensive than alternative technologies like laser trackers or photogrammetry, without occupying the work volume.
Implementation Method 1
a first camera and has an optical axis... acquire a digital image of the XY scale
Data Source
AI summary
A supplementary 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 supplementary metrology position coordinates determination 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 movable arm configuration and the other is coupled to a stationary element (e.g., a frame above the robot). The imaging configuration acquires an image of the XY scale, which is utilized to determine metrology position coordinates that are indicative of the end tool position, with an accuracy level that is better than the robot accuracy.