Torque Determination Using Calibration Correction for Rotating Members
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Solution Overview
Problem
Existing methods for determining torque between rotating members, such as in a bicycle's transmission, face precision issues due to eccentricity, inhomogeneity of encoders, and non-linearities of sensors, leading to errors in angular position measurement and torque calculation.
Innovation Solution
A method involving a test body with encoders and sensors, where a calibration procedure is performed by rotating the test body under a constant torque to define angular differences, allowing for correction of deviations and precise torque determination by using interpolation factors and calibration values to accurately calculate the applied torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a test body with encoders and sensors is used to determine torque between rotating members, then torque measurement capability is provided, but measurement precision deteriorates due to eccentricity, inhomogeneity of encoders, and non-linearities of sensors
Solution Approach 1:
The patent performs a calibration procedure before actual torque measurement to characterize and store correction values for encoder and sensor defects. By pre-measuring the angular positions under known conditions and storing correction data, the system compensates for manufacturing imperfections during subsequent torque measurements, thereby improving measurement precision despite inherent component defects.
2Measurement precision
If calibration procedures are implemented to correct sensor and encoder defects, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent creates a digital copy or model of the actual angular positions during calibration, storing correction values in a lookup table. Instead of physically modifying the sensor system, the patent uses software-based correction by comparing measured positions with pre-stored reference positions, thereby compensating for defects without adding complex hardware while improving measurement precision.
3Measurement precision
If multiple correction values and calibration procedures are used to account for encoder and sensor defects, then torque determination accuracy is improved, but processing time and complexity increase
Solution Approach 1:
The patent performs the complex calibration and correction value generation in advance, storing the results in a lookup table. During actual torque measurement, the system simply retrieves pre-calculated correction values based on measured angular positions, avoiding real-time complex calculations. This approach maintains high torque determination accuracy while minimizing processing time during operation.
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 method enhances torque determination precision by correcting for relative defects in the test body and sensor systems, enabling accurate real-time torque measurement without requiring additional angular sensors or constant speed rotation, particularly beneficial for bicycle transmissions.
Implementation Method 1
an encoder carrying a track capable of emitting a periodic signal representative of the rotational movement of the corresponding portion
Implementation Method 2
a sensor comprising a pattern of sensitive elements arranged at a reading distance from the track to deliver a signal representative of the angular position of the corresponding encoder
Implementation Method 3
a deformable structure which is arranged to transmit the torque between the members while allowing angular movement between said portions
Data Source
AI summary
The invention relates to a method for determining a torque applied between two rotating members, said method comprising a calibration procedure for the determination which provides for: rotating a test body through at least one revolution under a constant calibration torque between the members and using a determination system to define calibration values of the angular deviation as a function of the angle of rotation of said test body, the subsequent determination of the applied torque being obtained by correcting the angular deviation determined at a given angle with the corresponding calibration value.