Minimally-threaded screw alignment shifts ring laser gyroscope
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Solution Overview
Problem
Ring laser gyroscope alignment shifts due to temperature changes and unintentional contact between gyro mounting features and screws, leading to inaccurate calibration and degraded navigation performance.
Innovation Solution
The use of minimally-threaded screws with an unthreaded section contactlessly encased in through holes, preventing unintentional contact and maintaining critical angular relationships between the lasing plane and the reference mounting plane across temperature variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a fully-threaded screw is used to attach the gyro mounting feature to the gyro frame, then the screw provides secure mechanical fastening, but the threaded portion unintentionally contacts the side wall of the through hole, causing alignment shifts in the lasing plane relative to the reference mounting plane
Solution Approach 1:
The screw is segmented into distinct functional zones: a threaded portion for mechanical fastening and an unthreaded smooth portion for contactless passage through the through hole. This segmentation allows each portion to perform its specific function without interfering with the other, preventing alignment shifts while maintaining secure attachment.
Solution Approach 2:
The unthreaded smooth portion of the screw acts as an intermediary element between the threaded fastening portion and the through hole side wall. It provides a contactless interface that prevents direct mechanical interaction between the screw threads and the through hole, thereby eliminating the source of alignment errors.
2Ease of manufacture
If the screw threads contact the side wall of the through hole, then the screw can be easily manufactured with full threading, but the contact causes alignment shifts that are exacerbated by temperature changes
Solution Approach 1:
The screw design segments the threading to occur only at the distal end, while the proximal portion remains smooth and unthreaded. This segmentation maintains manufacturing feasibility while eliminating the harmful contact between threads and through hole side wall that causes temperature-dependent alignment shifts.
Solution Approach 2:
The screw exhibits local quality differentiation: the distal end has threading for fastening function, while the proximal end has a smooth surface for contactless passage. This localized variation in surface characteristics allows the screw to achieve both ease of manufacture and alignment stability.
3Measurement precision
If the angular relationship between the lasing plane and reference mounting plane shifts due to temperature effects, then the gyro can be recalibrated, but the calibration provides only a temporary fix as the alignment continues to wobble
Solution Approach 1:
The design applies preliminary anti-action by preventing the root cause of alignment shifts (thread contact with through hole side wall) before temperature changes can occur. The unthreaded smooth portion of the screw proactively eliminates the mechanism that would allow thermal expansion to cause alignment wobble, making recalibration unnecessary.
Solution Approach 2:
The unthreaded smooth portion of the screw provides beforehand cushioning by creating a contactless interface that accommodates thermal expansion without transmitting mechanical contact forces. This prevents the alignment wobble that would otherwise require temporary recalibration fixes.
4Adaptability or versatility
If multiple gyro mounting features are orthogonally mounted, then the multi-axis gyroscope provides comprehensive navigation data, but unintentional contact between screws and through holes causes shifts in the critical angular relationships between sense axes
Solution Approach 1:
Each screw in the multi-axis gyroscope assembly is segmented with an unthreaded smooth portion that prevents contact with the through hole side walls. This segmentation ensures that the orthogonal mounting of multiple gyro features does not result in cumulative alignment errors, maintaining precise angular relationships between sense axes.
Data Source
AI summary
A ring laser gyroscope configured to reduce alignment shifts in at least one critical alignment of the ring laser gyroscope is provided. The ring laser gyroscope includes reflective components configured to direct clockwise optical beams and counter-clockwise optical beams in at least one lasing plane; at least one ring-laser-gyro mounting feature having at least one respective through hole; and at least one minimally-threaded screw positioned in the at least one respective through hole. An unthreaded section of the minimally-threaded screw is contactlessly encased in the at least one respective through hole. A threaded-end of the at least one minimally-threaded screw is threaded in a respective at least one threaded hole in a gyro frame, the gyro frame spanning a reference mounting plane.