Brake Caliper Interface FBG Sensing for Accurate Braking Torque
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Solution Overview
Problem
Current methods for determining braking torque in brake systems are inaccurate and reliant on indirect measurements, often influenced by axial forces and limited in range, lacking compactness and independence from screw tightening torque.
Innovation Solution
A method using photonic sensors, specifically fiber-optic strain sensors, at the fixing interface between a brake caliper body and its support to detect deformation and strain, allowing for precise measurement of braking torque through a system of washer devices with integrated FBG sensors and an optical reading/interrogation unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If strain sensors are used to measure lateral forces at the brake caliper interface, then the braking force can be determined indirectly, but the measurement accuracy is poor and the measurable force range is limited
Solution Approach 1:
The patent replaces traditional mechanical strain sensors with fiber optic FBG (Fiber Bragg Grating) sensors that use optical principles instead of mechanical deformation. The FBG sensors measure strain through optical wavelength shifts, eliminating the limitations of mechanical strain gauges regarding measurement range and accuracy. This substitution enables precise measurement of both small and large forces without the sensitivity-range tradeoff inherent in mechanical sensors.
Solution Approach 2:
The patent changes the measurement parameter from electrical resistance change (in strain gauges) to optical wavelength shift (in FBG sensors). This parameter change allows for higher measurement precision and extended measurable range, as optical measurements are not subject to the same physical limitations as electrical strain sensors. The wavelength shift provides a more linear and accurate representation of the applied force across a wider range.
2Measurement precision
If indirect measurements of forces at different caliper points are used, then braking torque can be determined, but the results are influenced by axial forces from screw tightening torque
Solution Approach 1:
The patent extracts and isolates the measurement of lateral forces from the axial force components. By positioning FBG sensors specifically to detect only lateral force components at the caliper interface, the system separates the braking force measurement from the axial tightening forces. This extraction eliminates the interference from screw tightening torque that plagues traditional indirect measurement methods.
Solution Approach 2:
The patent introduces a specialized interface structure with FBG sensors as an intermediary between the caliper components. This intermediary structure is designed to transmit lateral forces to the sensors while blocking or excluding axial force transmission. The sensorized interface acts as a mediator that selectively couples lateral forces to the measurement system while decoupling axial forces, thereby eliminating their harmful influence on measurement accuracy.
3Ease of operation
If compact sensor devices are used for integration into the braking system, then ease of installation is improved, but measurement accuracy and reliability are compromised
Solution Approach 1:
The patent embeds the FBG sensors within the existing caliper interface structure, nesting the sensing elements inside the mechanical components. The fiber optic sensors are integrated into the caliper body or mounting interface, allowing them to be installed within the existing compact space without adding external bulk. This nesting approach maintains measurement reliability while preserving ease of installation, as the sensors become part of the existing structure rather than separate additions.
Solution Approach 2:
The patent designs the sensorized interface to serve multiple functions: structural support, force transmission, and measurement. The same interface components that provide mechanical function also house and protect the FBG sensors, eliminating the need for separate sensor mounting hardware. This multi-functionality reduces the overall complexity and size of the measurement system while maintaining high reliability through the robust integration of sensors into the load-bearing structure.
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 approach provides accurate, real-time measurement of braking torque with temperature compensation, improving precision and reducing dependence on axial forces, while being compact and versatile for integration into various brake systems.
Implementation Method 1
A method using photonic sensors, specifically fiber-optic strain sensors, at the fixing interface between a brake caliper body and its support to detect deformation and strain
Data Source
AI summary
A method for determining a braking torque at at least one fixing interface between a brake caliper body and a brake caliper support includes inserting at least one washer device at the at least one fixing interface, the washer device having at least one fiber-optic strain sensor of fiber Bragg grating type, detecting, by the at least one fiber-optic strain sensor, local deformation and/or strain acting in a respective detecting position, and generating at least one respective photonic signal representative of the detected deformation and/or strain, receiving the at least one first photonic signal, by an optical reading/interrogation unit optically connected to the at least one fiber-optic strain sensor, generating at least one electric signal representative of the detected local deformation and/or strain, based on the received first photonic signal, and determining the braking torque based on the at least one electrical signal.