Force-Based Build Platform Position Detection in Additive Fabrication
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Solution Overview
Problem
Existing additive fabrication systems face challenges in accurately determining the position of a build platform along the z-axis without increasing complexity or cost, particularly in systems where mechanical or optical sensing means are undesirable, and inaccuracies arise due to device geometry changes and load distortions.
Innovation Solution
The system measures the force applied to the build platform as it moves away from the container surface, utilizing the pattern of resistance forces to determine the position at which the build platform is flush against the surface, allowing for precise determination of the z-axis height without direct contact sensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If mechanical or optical sensing means are used to detect build platform position, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent replaces mechanical or optical sensing systems with a force-based detection method. The controller measures force applied to the build platform during movement and uses force pattern analysis to determine platform position and container surface contact points, eliminating the need for complex mechanical encoders or optical sensors.
Solution Approach 2:
The system uses the existing actuator and force measurement capabilities already present in the additive fabrication device to perform position detection. The same components used for moving the build platform are leveraged to detect its position through force pattern analysis during movement, rather than requiring separate dedicated sensing systems.
2Measurement precision
If mechanical sensing means are used to detect build platform position, then measurement precision is improved, but cost increases
Solution Approach 1:
The patent replaces expensive mechanical or optical sensing hardware with a software-based force pattern analysis approach. The controller uses force measurements taken during normal platform movement to calculate position information, avoiding the need for costly dedicated position sensing components.
Solution Approach 2:
The system leverages existing force measurement capabilities during platform movement to provide position detection functionality, rather than requiring additional expensive sensing hardware. The same actuator that moves the platform serves dual purposes: movement and position detection through force pattern analysis.
3Measurement precision
If direct contact sensing is used to detect build platform position, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent replaces direct contact sensing hardware with indirect force-based detection. Instead of using physical sensors that contact the build platform or container to detect position, the system measures force patterns during platform movement and infers position information from these force patterns through controller analysis.
Solution Approach 2:
The patent introduces force measurement as an intermediary between the build platform movement and position detection. Rather than directly sensing position through contact, the system measures the force applied during movement as an intermediate parameter, then uses this force data to calculate position information.
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 method provides reliable and accurate determination of the z-axis position, reducing errors caused by mechanical deformation and fluid viscosity, and is applicable to various additive fabrication devices with resistance forces, enhancing precision and reducing system complexity.
Implementation Method 1
one or more actuators configured to move the build platform relative to the container
Implementation Method 2
measure a force applied to the build platform during the step of moving the build platform away from the container
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
According to some aspects, techniques for determining a position of a build platform in an additive fabrication device are provided. According to some embodiments, forces resisting separation of the build platform from an opposing surface are measured and a position of the build platform with respect to the opposing surface is determined. In some embodiments, such forces may include fluid forces present during separation of a build platform from an interior surface of a liquid photopolymer container.