Print Head Rotational Error Compensation in 3D Printers

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Solution Overview

Problem

Low mass gantries in additive manufacturing systems are prone to positioning errors due to acceleration, deceleration, and external forces, leading to inaccuracies in print head positioning, which affects the quality of printed 3D parts.

Innovation Solution

The integration of accelerometers and gyroscopes on the print head to measure acceleration and rotational position, with a controller system that compensates for these errors by adjusting the movement of the print head and gantry actuators, ensuring accurate positioning.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If low mass gantries are used in additive manufacturing systems, then cost-effectiveness is improved, but positioning accuracy of the print head deteriorates due to acceleration and external forces

Engineering Contradiction:

Improvecost-effectivenessVSAvoidprint head positioning accuracy

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The system employs accelerometers and gyroscopes to continuously monitor the actual acceleration and rotational position of the print head, feeding this information back to the controller. The controller then calculates positioning errors based on this feedback and adjusts the gantry actuator commands to compensate for deviations, thereby maintaining positioning accuracy despite using low mass gantries

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent replaces purely mechanical positioning systems with an integrated sensor-based measurement and control system. Instead of relying solely on mechanical rigidity to maintain accuracy, the system uses electronic sensors (accelerometers and gyroscopes) and software algorithms to detect and correct positioning errors in real-time, substituting mechanical robustness with intelligent control

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Productivity

If low mass gantries are used to reduce system mass, then productivity and response time are improved, but rotational position stability deteriorates under acceleration and external forces

Engineering Contradiction:

Improveprinting speedVSAvoidrotational position stability

Core Design Contradiction:

ProductivityVSStability of the object's composition

Solution Approach 1:

The system transitions from static, passive mechanical stability to dynamic, active stability control. The low mass gantry enables rapid movement and high productivity, while the dynamic control system using accelerometers and gyroscopes continuously adapts to changing conditions during motion, calculating and compensating for rotational position errors in real-time to maintain stability throughout the printing process

Inventive Principle:

Principle #15Dynamics

3Device complexity

If traditional positioning systems are used without sensor compensation, then device complexity is reduced, but positioning error under acceleration increases

Engineering Contradiction:

Improvesystem simplicityVSAvoidprint head position accuracy

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The patent introduces accelerometers and gyroscopes as intermediary sensing elements between the print head and the control system. These sensors act as mediators that measure the actual motion and rotational position, providing data that the controller uses to calculate compensation values. This intermediary measurement layer enables the system to detect and correct positioning errors without fundamentally redesigning the entire positioning mechanism

Inventive Principle:

Principle #24Intermediary (Mediator)

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 solution effectively minimizes rotational position errors, enhancing the accuracy and quality of 3D printed parts by correcting for pitch, roll, and yaw misalignments caused by low mass gantries, while maintaining cost-effectiveness.

Implementation Method 1

A sensor fixedly mounted to the print head and configured to output a first signal that is directly or indirectly related to an acceleration of the print head

Methodology Applied

Scientific EffectAcceleration: Accelerometer

Implementation Method 2

a gyroscope fixedly mounted to the print head and configured to output a second signal related to a rotational position of the print head

Methodology Applied

Scientific EffectRotational position sensing: Gyroscope

Data Source

PatentUS10889068B1Rotational position error compensation of print heads in a 3D printer and methods thereof

Publication Date: 2021.01.12 STRATASYS INC

AI summary

A 3D printer is configured to print a 3D part. The 3D printer includes a print head carried by a head gantry and configured to operably move the print head along planar tool paths. The 3D printer includes at least one head gantry actuator coupled to the head gantry and configured to move the print head in a plane and a print head actuator coupled to the print head and configured to move the print head in a direction substantially orthogonal to the plane. A sensor is fixedly mounted to the print head and configured to output a first signal that is directly or indirectly related to an acceleration of the print head, and a gyroscope is fixedly mounted to the print head and configured to output a second signal related to a rotational position of the print head. The 3D printer includes a controller configured to determine a rotational position error of the print head relative to a predetermined position based on the first signal and the second signal and to output one or more signals to the at least one head gantry actuator and/or the print head actuator to compensate for the rotational position error of the print head.