3D Printing Robot Joint Control for Accurate Printhead Trajectories

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Solution Overview

Problem

Three-dimensional object printing apparatuses with multi-axis robots experience operational errors in movable joint members, leading to significant deviations in the actual movement route of the print head from the ideal route, resulting in reduced printing quality.

Innovation Solution

A three-dimensional object printing apparatus utilizing a 6-axis vertical articulated robot with a liquid ejecting unit and a controller that synchronizes the ejection operation with the robot's movement, reducing the number of joint sections rotated during printing to minimize operational errors and maintain ink stability, while allowing full operation during non-printing modes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If all movable joint members are operated during printing, then the degree of freedom and adaptability of the robot is improved, but operational errors overlap causing significant deviation from the ideal movement route

Engineering Contradiction:
Improvedegree of freedomVSAvoidmovement route accuracy
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The robot's joint members are segmented into two groups: those operated during printing and those not operated. This segmentation allows selective activation of only necessary joints (e.g., 3 out of 6) during printing, reducing cumulative operational errors while maintaining sufficient adaptability for the printing task.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Instead of operating all joint members, only a partial subset is activated during printing. This partial action approach reduces the accumulation of operational errors from multiple joints while still providing adequate freedom of movement for the printing operation.

Inventive Principle:
Principle #16Partial or excessive action

2Adaptability or versatility

If all movable joint members are operated during printing, then the robot can achieve complex movement routes, but the printing quality deteriorates due to significant deviation from the ideal route

Engineering Contradiction:
Improvemovement capabilityVSAvoidprinting quality
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The joint members are divided into operational and non-operational groups during printing. This segmentation reduces the number of active joints, thereby reducing cumulative operational errors and improving the reliability of the printing process while maintaining necessary movement capability through the selected joints.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The operational state of joint members is changed from 'all operated' to 'selectively operated' during printing. This parameter change in the robot's operation mode reduces the accumulation of errors and improves printing quality while maintaining adequate adaptability.

Inventive Principle:
Principle #35Parameter changes

3Manufacturing precision

If the number of joint sections rotated during printing is reduced, then the deviation from ideal route is reduced, but the degree of freedom during non-printing operations is limited

Engineering Contradiction:
Improveroute accuracyVSAvoidoperational freedom
Core Design Contradiction:
Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The robot's operational configuration is made dynamic, switching between two modes: during printing, only necessary joints are operated to ensure accuracy; during non-printing operations, all joints can be operated to maximize freedom of movement. This dynamic adaptation resolves the contradiction between precision and versatility.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The robot alternates between different operational states: a restricted state during printing (fewer joints operated) and an unrestricted state during non-printing operations (all joints operated). This periodic switching allows the system to optimize for accuracy when needed and for versatility when not printing.

Inventive Principle:
Principle #19Periodic action

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 configuration reduces the deviation of the actual movement route from the ideal route, enhancing printing quality and increasing the degree of freedom during non-printing operations by limiting the number of joint sections rotated during printing.

Implementation Method 1

a liquid ejecting unit (300) that ejects liquid

Methodology Applied
Scientific EffectElectrohydrodynamics: Electrohydrodynamics

Data Source

PatentEP3991976B1Three-dimensional object printing apparatus and three-dimensional object printing method
Publication Date: 2023.12.06 SEIKO EPSON CORP
  • EP3991976B1 patent drawingFigure 1
  • EP3991976B1 patent drawingFigure 2
  • EP3991976B1 patent drawingFigure 3~4

AI summary

A three-dimensional object printing apparatus includes a liquid ejecting head that ejects a liquid to three-dimensional work, and a moving mechanism that changes a relative position of the liquid ejecting head with respect to the work. The moving mechanism includes a number N (N is a natural number of 2 or greater) of joints rotatable around different rotational axes. When a printing operation that causes the liquid ejecting head to eject a liquid while causing the moving mechanism to change the relative position of the liquid ejecting head with respect to the work is executed, the number of joints that rotate during the printing operation among the number N of joints is M (M is a natural number smaller than N).