Robot Print Head Calibration Using Camera-Measured Impact Points
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Solution Overview
Problem
Existing methods for calibrating multi-axis robots equipped with a camera and a print head are complex and do not allow for optimized calibration, particularly in achieving precise positioning of the print head relative to a surface.
Innovation Solution
A method that determines the oriented position of the print head's reference frame in the wrist reference frame using a transition matrix defined by six parameters, achieved through a series of steps involving camera aiming, impact printing, coordinate measurement, and optimization of deviations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If automatic verification and correction of print head position is performed before each cycle, then positioning precision is improved, but device complexity and operational time increase
Solution Approach 1:
The patent performs calibration operations before actual printing cycles by determining the transformation matrix between camera and print head reference frames in advance. This preliminary calibration stores positioning data that can be reused, avoiding the need for complex verification before each printing cycle while maintaining precision.
2Manufacturing precision
If complex calibration methods are used to achieve precise print head positioning, then manufacturing precision is improved, but ease of operation deteriorates
Solution Approach 1:
The system performs self-calibration by automatically determining the transformation matrix between reference frames using the camera and print head themselves as measurement tools. The calibration process is autonomous, requiring minimal external intervention or complex manual procedures, thus improving ease of operation while maintaining precision.
3Measurement precision
If multiple measurement points and optimization steps are performed, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The patent performs comprehensive measurements at multiple points and optimization calculations during an initial calibration phase before actual production printing. This preliminary action establishes a transformation matrix that can be reused, achieving high measurement precision without repeating time-consuming measurements during each printing cycle.
Data Source
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AI summary
According to this method, a mathematical surface (PrefBF) is determined (104), a print head is brought into a first and then into a second position, where a first impact and a second impact are printed (106, 110), then the coordinates of a characteristic point (P1,4BF,P2,4BF) of the first or second impact are measured (108, 112). The coordinates of a first intersection point (I1,4BF) and those of a second intersection point (I2,4BF) are expressed (114). A deviation (εk) based on the coordinates of the characteristic points (Pk,jBF) and intersection points (Ik,jBF) is expressed (120). An objective function (F) is constructed (122) whose variables are the deviations (εk). We determine (124) values of six parameters (X1-X6) of a transition matrix (TTCP→PG) which minimize the objective function (F). We use (128) these six parameters (X1-X6) to define an oriented position of the frame (TCP) linked to the print head in the frame linked to the wrist.