Multi-turn Sensor Gear Ratio Accuracy
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Solution Overview
Problem
Existing multi-turn sensors for measuring angular positions of rotatable bodies, such as steering wheels, face accuracy issues due to gear reduction ratios, which reduce sensor resolution and accuracy, especially when measuring more than 360 degrees of rotation.
Innovation Solution
A multi-turn angular position sensor system utilizing two sensor gears with different numbers of teeth, where the second sensor gear has one more tooth than the first, and a processor calculates the main gear's position using equations that account for the gear ratio and the difference in rotations between the sensor gears, ensuring accurate measurement across multiple turns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If gear reduction ratio is used to measure multiple turns, then the measurement range is extended, but the resolution and accuracy are reduced
Solution Approach 1:
The patent divides the measurement system into two independent single-turn sensors, each measuring a different sensor gear. By segmenting the measurement function across multiple sensors rather than using one sensor with gear reduction, the system achieves multi-turn capability without sacrificing the resolution and accuracy of individual sensors.
Solution Approach 2:
The patent introduces sensor gears with different tooth counts as intermediaries between the main gear and the sensors. These intermediary gears translate the main gear's rotation into different rotational speeds for each sensor, enabling multi-turn measurement while maintaining sensor accuracy through mathematical processing of the differential measurements.
2Adaptability or versatility
If multi-turn counters and specialized algorithms are used, then the measurement range is extended, but the device complexity increases
Solution Approach 1:
The patent replaces complex mechanical multi-turn counter mechanisms with a simpler system using two single-turn sensors and basic mathematical processing. The multi-turn information is derived through algorithms that process the differential measurements from the two sensors, eliminating the need for specialized mechanical multi-turn counting components.
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 system provides high accuracy and simplicity, maintaining resolution by calculating the main gear's position with improved precision, even after multiple revolutions, thereby addressing the limitations of existing technologies.
Implementation Method 1
At least one of the first or second angular position sensors is a Hall-effect sensor
Data Source
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AI summary
A multi-turn angular position sensor a main gear configured to couple to and rotate, in response to rotation of a rotation member, over a main gear rotation range, a first sensor gear engaged with the main gear and configured to experience more angular rotation than the main gear in response to rotation of the main gear, and a second sensor gear engaged with the main gear and configured to experience more angular rotation than the main gear and less angular rotation than the first sensor gear in response to rotation of the main gear. The angular position sensor also includes a first angular position sensor configured to sense rotation of the first sensor gear and to generate a first output signal indicative of rotation of the first sensor gear, and a second angular position sensor configured to sense rotation of the second sensor gear and to generate a second output signal indicative of rotation of the second sensor gear. The main gear and the first and second sensor gears are configured such that a difference in a number of 360 degree revolutions experienced by the first sensor gear and the second sensor gear will be one 360 degree revolution or less in response to the main gear rotating through an expected full main gear rotation range greater than 360 degrees. The angular position sensor further includes a processor configured to receive the first and second output signals, determine a difference between rotation of the first sensor gear and rotation of the second sensor gear based on the first and second outputs, determine an overall angular rotation of the first or second sensor gear from an initial angular position of the first or second sensor gear based on the difference and a present angular position of the first or second sensor gear, respectively, and determine an angular position of the main gear based on the overall angular rotation of the first or second sensor gear.