Bicycle Bottom Bracket Torque Sensing with Gyroscope Calibration
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Solution Overview
Problem
Existing bottom brackets in bicycles face challenges in accurately detecting torque due to potential misalignment of torque sensors, which can be costly to correct with additional components like poka-yoke-units or complex to assemble with strain gauges, and require expensive four-sensor setups.
Innovation Solution
Incorporating a gyroscope to determine the rotational position of the torque sensor and calibrate it accordingly, allowing for accurate torque calculation without additional sensors or complex assemblies, using strain gauges aligned perpendicular to crank force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If four torque sensors are used to detect torque accurately, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces the mechanical approach of using multiple torque sensors with a gyroscopic system that uses rotational mechanics and mathematical calculations. The gyroscope detects rotational position, and the control unit calculates torque based on this data, substituting physical sensor redundancy with a different physical principle that achieves the same measurement accuracy with fewer components.
Solution Approach 2:
The patent changes the parameter being directly measured from torque (using strain gauges) to rotational position (using a gyroscope). By measuring rotational position and deriving torque from this parameter through calculation, the system achieves accurate torque detection without requiring multiple torque sensors, thus reducing device complexity while maintaining measurement precision.
2Reliability
If a poka-yoke-unit is added to prevent rotation of the bottom bracket, then reliability is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent replaces the mechanical poka-yoke-unit (a physical tab structure) with an electronic/digital solution using a gyroscope and control unit. Instead of preventing rotation mechanically, the system detects rotational position electronically and compensates for it through calculation, eliminating the need for additional mechanical components while maintaining reliability.
Solution Approach 2:
The gyroscope acts as an intermediary between the bottom bracket rotation and the torque measurement system. Rather than directly preventing rotation with a mechanical tab, the gyroscope mediates by detecting the rotational position and providing this information to the control unit, which then compensates for the rotation effect, thus maintaining reliability without mechanical intervention.
3Measurement precision
If torque sensors are aligned perpendicular to crank force direction, then measurement precision is improved, but ease of manufacture deteriorates due to assembly complexity
Solution Approach 1:
The patent replaces the mechanical alignment requirement (torque sensors perpendicular to crank force) with a gyroscopic detection system. Instead of requiring precise mechanical alignment during assembly, the gyroscope detects the actual rotational position, and the control unit calculates torque based on this detected position, eliminating the need for precise manual alignment while maintaining measurement precision.
Solution Approach 2:
The patent transitions from a static alignment requirement (fixed perpendicular orientation) to a dynamic solution where the system adapts to the actual rotational position. The gyroscope continuously detects rotational position, and the control unit dynamically adjusts calculations based on the detected orientation, allowing the system to maintain accuracy regardless of initial assembly alignment.
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 torque detection and calculation by correcting for sensor misalignment, simplifying manufacturing and assembly, and providing real-time recalibration during use to maintain accuracy.
Implementation Method 1
the control unit comprises a gyroscope for determining a rotational position of the body and thereby of the at least one torque sensor with respect to the longitudinal center axis of the body
Implementation Method 2
The torque sensor is preferably a strain gauge via which a deformation of the body can be detected. The force acting on the body and finally the torque can be calculated from the deformation of the body i.e. of the strain gauge
Data Source
Figure 1~2
Figure 1
Figure 3~4
AI summary
The invention relates to a bottom bracket (1) of a bicycle (17) with a control unit (3) and at least one torque sensor (8a, 8b). The control unit (3) comprises a gyroscope (10) for calibrating the torque sensor (8a, 8b) depending on their offset rotational position. The invention also relates to a bicycle (17) with the bottom bracket (1) and a method for detecting a torque in the bicycle (17).