Electric Brake Device Dual Estimation System
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Solution Overview
Problem
Existing electric brake devices face challenges in achieving sufficient resolution in normal-use regions while maintaining a wide dynamic range, leading to increased costs and potential discomfort for drivers due to varying friction coefficients and brake fade during intense braking.
Innovation Solution
The electric brake device incorporates a dual-estimation system, using a direct estimator for low-braking-force ranges and an indirect estimator beyond that range, leveraging motor rotation angle and current sensors to estimate braking force, allowing for high accuracy and cost reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the braking force sensor is configured to have a wide dynamic range to detect pressing force during brake fade, then the detection range is improved, but the resolution in the normal-use region deteriorates
Solution Approach 1:
The patent divides the braking force detection into two segments: normal-use region (below brake fade threshold) and brake fade region (above threshold). A first braking force sensor handles the normal-use region with high resolution, while a second braking force sensor handles the brake fade region with wide dynamic range. This segmentation allows each sensor to be optimized for its specific operating range, resolving the contradiction between wide detection range and high resolution.
2Measurement precision
If a highly accurate load sensor is configured to obtain sufficient resolution in the normal-use region, then the measurement precision is improved, but the cost increases
Solution Approach 1:
The patent segments the detection task between two sensors with different performance levels and cost structures. The first sensor (for normal-use) can be a cost-effective solution with high resolution, while the second sensor (for brake fade) handles extreme conditions. This segmentation avoids the need for a single expensive high-precision sensor to cover the entire range, thereby reducing overall cost while maintaining precision where needed.
Solution Approach 2:
The patent employs a second braking force sensor that is specifically designed for the brake fade region, which is a less frequent operating condition. This sensor can be optimized for wide dynamic range rather than high resolution, making it a more cost-effective solution for handling extreme but less critical operating conditions, while the primary high-precision sensor handles the majority normal-use scenarios.
3Adaptability or versatility
If the braking force sensor is configured with wide dynamic range for brake fade detection, then the adaptability is improved, but the device complexity increases
Solution Approach 1:
The patent segments the braking force detection function across two specialized sensors rather than using one complex sensor attempting to handle all conditions. The first sensor is optimized for normal-use with high resolution, and the second sensor is optimized for brake fade with wide dynamic range. This functional segmentation simplifies the design requirements for each individual sensor compared to a single sensor attempting to meet all requirements simultaneously.
Solution Approach 2:
The control device integrates multiple functions: it processes signals from both braking force sensors, determines whether brake fade is occurring based on the sensor readings, and appropriately weights the contributions of each sensor to the final braking force estimation. This multi-functional control approach manages the complexity by creating a unified system that adapts its behavior based on operating conditions.
Data Source
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AI summary
The electric brake device includes an electric motor (6), a friction member operator (5), a friction member (4), a brake rotor (3), and a control device (2). A braking force estimator (16) provided in the control device (2) includes: a direct estimator (17) configured to convert output of a braking force sensor (19) which detects a load or displacement corresponding amount, to a braking force; and an indirect estimator (18) configured to estimate the braking force on the basis of information other than output of the braking force sensor (19). A range in which the braking force is estimated by the direct estimator (17) is a specified low-braking-force range, and in a range beyond this range, estimation of the braking force is performed by the indirect estimator (18).