Brake Caliper Clamping Force Sensing With Limit Stop Estimation
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Solution Overview
Problem
Existing brake caliper force detection methods in BBW systems face limitations in feasibility, cost, accuracy, and reusability, with sensors covering the entire range being impractical and estimates being subject to uncertainties due to component changes and thermal effects.
Innovation Solution
A device comprising a force sensor with a limited reading range and a mechanical limit stop element, combined with a force estimator module, to accurately measure and estimate clamping forces beyond the sensor's range using a caliper stiffness model.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a force sensor with a wide reading range is used to cover the entire operating range of the brake caliper, then the measurement range is improved, but the accuracy and resolution deteriorate
Solution Approach 1:
The patent divides the force measurement range into two segments: a low-force range measured by a force sensor with limited reading range (optimized for high accuracy), and a high-force range estimated by a force estimator module. This segmentation allows each component to be optimized for its specific range, resolving the contradiction between wide range and high accuracy.
Solution Approach 2:
The force estimator module acts as an intermediary that takes over measurement tasks when the force exceeds the sensor's reading range. The estimator uses a caliper stiffness model and additional measurements to calculate the force, allowing the system to handle high forces without compromising the sensor's accuracy in the low-force range.
2Adaptability or versatility
If a force sensor with a high reading range is used, then the feasibility is improved, but the cost increases
Solution Approach 1:
The measurement function is segmented between a low-cost force sensor with limited range and a force estimator module. This allows the use of an inexpensive sensor that only needs to cover the low-force range, while the estimator handles high-force measurements computationally, significantly reducing overall system cost.
Solution Approach 2:
Instead of using an expensive physical sensor capable of measuring the entire force range, the patent creates a virtual copy of the sensor capability through the force estimator module, which calculates force values based on a stiffness model and additional measurements, replacing the need for an expensive wide-range sensor.
3Measurement precision
If a force sensor with a limited reading range is used, then the accuracy is improved, but the adaptability deteriorates
Solution Approach 1:
The force detection system achieves multi-functionality by combining a force sensor optimized for low-force measurements with a force estimator module that handles high-force measurements. This universal system can accurately detect forces across the entire operating range of the brake caliper, from low to high forces, using two different measurement approaches.
Solution Approach 2:
The force estimator module serves as an intermediary that extends the adaptability of the force detection system. When the actual force exceeds the sensor's limited reading range, the estimator calculates the force value, allowing the system to adapt to high-force conditions without requiring the sensor itself to have a wide range.
4Ease of manufacture
If an estimator is used to indirectly calculate the applied force, then the cost is reduced, but the accuracy deteriorates due to uncertainties
Solution Approach 1:
The patent applies partial estimation by using the force estimator module only when necessary (when force exceeds the sensor's reading range). For low-force measurements within the sensor's range, direct high-accuracy sensing is used. This partial use of estimation minimizes the impact of estimation uncertainties while maintaining overall system accuracy.
Solution Approach 2:
The system uses feedback from additional measurements (position, current, temperature) to continuously update the force estimation through a caliper stiffness model. This feedback mechanism compensates for uncertainties and variabilities in the estimation process, improving accuracy while maintaining the cost benefits of using an estimator.
Data Source
AI summary
A device for detecting a clamping force of a brake caliper of a vehicle braking system is provided. The device has a force sensor, a force transmitting element suitable for transmitting the clamping force exerted by the brake caliper to the force sensor, and a mechanical limit stop element. The force transmitting element is movable when subjected to the clamping force exerted by the brake caliper. The force sensor is configured to measure the clamping force up to a sensor force threshold value that is lower than a maximum clamping force exertable by the brake caliper. The mechanical limit stop element is configured to be engaged by the force transmitting element when the clamping force exceeds the sensor force threshold value.