Robot Print Head Position Correction via Optical Feedback

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Solution Overview

Problem

Existing printing systems face challenges in achieving high-precision printing due to deviations in the print head's trajectory caused by vibration, especially when the target object lacks image processing patterns for detecting trajectory shifts.

Innovation Solution

A printing method and robot system that utilize a robot with a print head and an optical sensor with a constant relative positional relationship. The system detects the actual position of the print head by comparing images captured at different timings and corrects its position based on deviations from the intended trajectory.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a rotation angle sensor and piezo actuator are used to correct print head position, then printing without strips is achieved, but high-precision printing is difficult due to trajectory deviation from vibration

Engineering Contradiction:
Improveprinting precisionVSAvoidtrajectory stability
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The patent uses an optical sensor to continuously detect the actual position of the print head during movement and feeds this information back to a control device. The control device compares the actual position with the intended trajectory and generates correction signals to adjust the print head position in real-time, forming a closed-loop feedback system that compensates for vibration-induced deviations.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent replaces the mechanical rotation angle sensor and piezo actuator system with an optical sensing system. Instead of using mechanical sensors to detect position and mechanical actuators to correct position, the system uses optical sensors to detect position and electronically controls the robot arm to correct position, substituting mechanical correction with electronic control.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Device complexity

If no image processing pattern is provided on the target object, then the system is simpler, but trajectory shifts cannot be detected

Engineering Contradiction:
Improvesystem complexityVSAvoidtrajectory detection accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent makes the target object itself serve as the reference for position detection. The optical sensor uses the target object's surface features or markings to determine the print head's actual position, eliminating the need for separate detection patterns. The system leverages the target object's own characteristics for self-reference and trajectory verification.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent integrates multiple functions into the optical sensor: it serves both as a positioning reference (replacing separate detection patterns) and as a trajectory verification tool. The same optical sensor that detects print head position also verifies whether the target object is properly positioned, making the system more universal and reducing overall complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 approach enables high-precision printing by accurately detecting and correcting the print head's position, even without image recognition patterns on the target object, thereby minimizing deviations and enhancing printing accuracy.

Implementation Method 1

detecting an actual position of the print head by moving the print head along the printing trajectory and comparing two images captured by the imaging element at different imaging timings

Methodology Applied
Scientific EffectImage processing: Image Processing

Data Source

PatentEP4497606A1Printing method and robot system
Publication Date: 2025.01.29 SEIKO EPSON CORP
  • EP4497606A1 patent drawingFigure 1
  • EP4497606A1 patent drawingFigure 2
  • EP4497606A1 patent drawingFigure 3

AI summary

A printing method using a robot, the robot having a robot main body provided with a robot arm, a print head arranged on the robot arm, and an optical sensor that is provided with an imaging element for imaging a target object and that has a constant relative positional relationship with the print head, the printing method being for performing a printing operation on the target object by relatively moving the target object and the print head along a printing trajectory, the printing method comprising: detecting the actual position of the print head by moving the print head along the printing trajectory and comparing two images captured by the imaging element at different imaging timings and correcting a position of the print head based on a deviation of the actual position from the printing trajectory.