Fiber Optic Rotation Sensor Using Eccentric Strain Deflection
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Solution Overview
Problem
Current technologies lack an effective method to accurately determine the rotational position or displacement of a shaft using strain sensors.
Innovation Solution
A sensor apparatus comprising resilient members and strain sensors positioned strategically relative to an eccentric member on a rod, where the strain measured by the sensors correlates with the rotational position of the rod, utilizing fiber Bragg gratings and temperature compensation to provide accurate rotational position, direction, and velocity measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If strain sensors are used to measure shaft rotation, then rotational position can be determined, but the measurement precision is insufficient
Solution Approach 1:
The patent divides the measurement system into multiple independent strain sensors (typically three or more) positioned at different angular locations around the shaft. Each sensor measures strain at its specific position, and the controller integrates these segmented measurements to determine the complete rotational position, thereby improving both precision and reliability
Solution Approach 2:
The patent combines the outputs from multiple strain sensors to achieve accurate rotational position measurement. The controller processes and merges the strain signals from all sensors, using algorithms to calculate the shaft's angular position with high precision, resolving the contradiction between individual sensor limitations and system-level accuracy requirements
2Measurement precision
If multiple resilient members and strain sensors are used to improve measurement accuracy, then rotational position precision improves, but device complexity increases
Solution Approach 1:
The patent designs the resilient members and strain sensors to serve multiple functions: they simultaneously measure radial displacement, provide mechanical coupling between the rotating shaft and stationary sensors, compensate for thermal effects, and maintain precise geometric relationships. This multi-functionality reduces the need for separate components, thereby improving measurement precision without proportionally increasing device complexity
Solution Approach 2:
The patent utilizes the change in strain sensor output parameters (electrical resistance, capacitance, or optical properties) in response to mechanical strain on the resilient members. By measuring these parameter changes and converting them to rotational position data, the system achieves high measurement precision using the inherent properties of the components rather than adding complex measurement infrastructure
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
Enables precise determination of rotational position, direction, and velocity of a shaft, allowing for accurate counting of rotations and measurement of velocity and acceleration.
Implementation Method 1
The first strain sensor is a fiber Bragg grating operatively connected to a fiber Bragg grating interrogator device
Implementation Method 2
the rod member includes a first eccentric member which causes the first resilient member to deflect as the rod member rotates
Implementation Method 3
a first strain sensor operatively connected to the first resilient member, wherein the first strain sensor measures the strain in the first resilient member
Data Source
AI summary
A sensor apparatus includes a resilient member positioned near a rod member and a strain sensor operatively connected to the resilient member. The rod member includes an eccentric member, which causes the resilient member to deflect as the rod member rotates. The strain sensor measures the strain in the resilient member due to the deflections caused by the eccentric member. The amount of strain relates to a rotational position of the rod member.