Isolated Optical Encoder for Vacuum Robot Drive Position Sensing
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Solution Overview
Problem
In vacuum environments, conventional robotic manipulators face challenges with out-gassing, power distribution, and heat removal, making it difficult to integrate active components like sensors and actuators, which limits the functionality of robotic arms in substrate processing applications.
Innovation Solution
A robot drive position sensor system is developed using an optical encoder with a transparent environment separation barrier, allowing a camera outside the vacuum environment to view a reference member inside through an aperture, while preventing exposure of the sensor components to the vacuum, thus avoiding out-gassing and allowing for accurate position sensing without the need for specialized encasements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If active sensor components are integrated inside the vacuum housing, then position sensing functionality is improved, but out-gassing and contamination of the vacuum environment worsen
Solution Approach 1:
The system is divided into two separate environments: the vacuum housing containing the reference member and the atmospheric environment containing the camera. The transparent barrier segments the system, allowing optical communication while maintaining environmental separation. This resolves the contradiction by enabling position sensing functionality without exposing vacuum-sensitive components to the vacuum environment.
Solution Approach 2:
A transparent barrier (window or membrane) acts as an intermediary between the vacuum and atmospheric environments. It allows optical signals to pass through while preventing direct contact between the camera and vacuum environment. This intermediary enables position sensing while eliminating out-gassing issues.
2Reliability
If the camera is placed outside the vacuum housing, then protection from vacuum conditions is improved, but the ability to directly sense position inside the housing worsens
Solution Approach 1:
The transparent barrier serves as an intermediary that enables optical communication between the atmospheric environment (where the camera resides) and the vacuum environment (where the reference member is located). This allows the camera to sense position accurately while remaining protected outside the vacuum housing.
Solution Approach 2:
The system replaces direct mechanical contact sensing with optical sensing through the transparent barrier. The camera captures images of the reference member through the barrier, and image processing algorithms determine position without physical contact. This substitution enables sensing while maintaining environmental separation.
3Reliability
If a transparent barrier is introduced to separate environments, then vacuum integrity is improved, but optical signal transmission quality worsens
Solution Approach 1:
The transparent barrier is positioned and designed with specific local properties (material composition, thickness, optical coating) optimized for the aperture region where optical transmission is required. This local optimization maintains vacuum integrity while minimizing degradation of image quality through the barrier.
Solution Approach 2:
The transparent barrier material is selected and potentially coated to have specific optical transmission characteristics. The material is chosen to be transparent to the wavelengths used by the camera for imaging the reference member, ensuring high-quality optical signal transmission while maintaining vacuum separation.
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 enables the integration of position sensing in vacuum environments without exposing the sensor components to harmful conditions, enhancing the functionality and reliability of robotic manipulators in substrate processing by maintaining the vacuum integrity and allowing for precise position tracking.
Implementation Method 1
the transparent environment separation barrier allows the camera to view the image coming from inside the housing
Data Source
AI summary
An apparatus including a frame, an optical sensor connected to the frame, and an environment separation barrier. The frame is configured to be attached to a housing of a motor assembly proximate an aperture which extends through the housing. The optical sensor comprises a camera. The environment separation barrier is configured to be connected to the housing at the aperture, where the environment separation barrier is at least partially transparent and located relative to the camera to allow the camera to view an image inside the housing through the environment separation barrier and the aperture.