Optical Shaft Position Sensor for Dusty Environments
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Solution Overview
Problem
Existing automated storage and retrieval systems face challenges in accurately determining the rotational position of rotating shafts, particularly in environments with dust and debris, which can lead to inaccuracies and complex constructions.
Innovation Solution
A position sensing device comprising a reflector attached to the rotating shaft and a distance measuring unit that emits and receives a beam of radiation parallel to the shaft, allowing for high-resolution measurement of the rotational position without being affected by dust and debris.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional encoders are used to determine rotational position, then measurement capability is provided, but measurement precision deteriorates in environments with dust and debris
Solution Approach 1:
The patent replaces mechanical encoders with an optical measurement system consisting of a reflector attached to the rotating shaft and a distance measuring unit (laser scanner) that emits and receives light beams. This optical system is immune to dust and debris that plague mechanical encoders, thereby resolving the contradiction between measurement precision and susceptibility to harmful environmental factors.
Solution Approach 2:
The reflector serves as an intermediary element attached to the rotating shaft. Instead of directly measuring the shaft position with sensitive mechanical components, the system uses the reflector to modulate the optical beam, creating a measurement signal that is insensitive to environmental contamination while accurately reflecting the rotational position.
2Measurement precision
If complex encoder systems are used to achieve accurate measurement, then device complexity increases
Solution Approach 1:
The patent replaces complex mechanical encoder systems with a simpler optical arrangement comprising a reflector and a distance measuring unit. This substitution reduces mechanical complexity while maintaining or improving measurement precision, as the optical system has fewer moving parts and no contact components requiring maintenance.
Solution Approach 2:
Instead of directly measuring the rotational position with complex sensors, the system creates an optical copy of the rotational motion through the reflector's movement. The laser scanner tracks the reflector's position, generating measurement data that replicates the shaft's rotational state without requiring direct mechanical coupling or complex sensing mechanisms.
3Reliability
If mechanical encoders are used in rotating shafts, then rotational position can be determined, but reliability decreases due to breakage risk
Solution Approach 1:
The patent eliminates mechanical encoders that are prone to breakage and contamination from the rotating shaft system. The optical measurement system with the reflector and laser scanner has no contact components on the rotating part, significantly improving reliability and resistance to breakage while enabling rotational position determination.
Solution Approach 2:
The patent extracts the measurement function from the mechanical shaft system by attaching a passive reflector to the shaft while keeping the active laser scanner stationary. This separation removes the vulnerable mechanical encoder components from the rotating environment, improving the strength and reliability of the overall measurement system.
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
The solution provides a robust and accurate method for determining the rotational position of rotating shafts, improving measurement resolution and reducing errors, while also simplifying the structural design and reducing the risk of breakage.
Implementation Method 1
a distance measuring unit arranged to emit a beam of radiation towards a portion of the reflector, as the shaft and reflector are rotated with respect to the distance measuring unit, and to receive a return beam generated when the emitted beam is reflected by the portion of the reflector
Data Source
AI summary
The invention relates to a position sensing device (10) for determining a rotational position of a rotating shaft (12) of a remotely operated vehicle of a system (1) for storing and retrieving goods holders, said rotating shaft (12) being a wheel axle of the remotely operated vehicle. The device comprises a reflector (14) attached to the rotating shaft so as to rotate simultaneously with said shaft (12), a distance measuring unit (16) arranged to emit a beam (18) of radiation towards a portion of the reflector (14), wherein the emitted beam is parallel to the rotating shaft, as the shaft (12) and the reflector (14) are rotated with respect to the distance measuring unit (16), and to receive a return beam (20) generated when the emitted beam (18) is reflected by the portion of the reflector (14). The distance measuring unit (16) is configured to output a signal based on a distance of said beam to said portion of the reflector (14), wherein a rotational position of the rotating shaft (12) is determined based on the output signal of measured distance from said distance measuring unit (16). The invention further relates to a method for determining rotational position of a rotating shaft (12).