Electric Braking System Adaptive Force Control
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Solution Overview
Problem
Existing electric braking systems face challenges in achieving high resolution for detecting pressing force in regions of low vehicle deceleration and high reliability in regions of high deceleration, while also minimizing unnecessary energization to the electric motor due to ineffective displacement.
Innovation Solution
The system includes operation amount acquisition means, pressing force acquisition means, and position acquisition means, with control means that compute an estimated pressing force value based on the position of the electric motor, adjusting contribution degrees to prioritize actual or estimated pressing force values depending on the operation amount, thereby improving resolution and reliability, and reducing unnecessary energization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pressing force feedback control is executed using actual pressing force value in region of small vehicle deceleration, then reliability of feedback control is improved, but resolution of detecting pressing force is insufficient due to low sensitivity in this region
Solution Approach 1:
The patent introduces an estimated pressing force value as an intermediary to bridge the gap between actual pressing force detection and control requirements. This estimated value, derived from motor position and stiffness characteristics, serves as a mediator that provides sufficient resolution in low-deceleration regions where actual pressing force sensitivity is low, while maintaining system reliability through weighted combination with actual measurements.
Solution Approach 2:
The patent dynamically changes the weighting parameters (contribution degrees) of actual versus estimated pressing force values based on operating conditions. In regions of small vehicle deceleration, the contribution degree of estimated pressing force is increased to improve resolution, while in regions of large deceleration, the contribution degree of actual pressing force is increased to ensure reliability. This parameter adaptation resolves the contradiction between resolution and reliability.
2Reliability
If feedback control is executed with high reliability in region of large vehicle deceleration, then consistency of vehicle deceleration is improved, but unnecessary energization occurs due to ineffective displacement of electric motor
Solution Approach 1:
The patent employs feedback control that compares target pressing force with actual pressing force to determine contribution degrees. By continuously monitoring the deviation between target and actual values, the system adjusts the weighting between actual and estimated pressing force measurements, enabling reliable control while minimizing unnecessary motor energization through adaptive feedback adjustment.
Solution Approach 2:
The patent makes the contribution degrees dynamic rather than fixed, allowing the system to adapt to changing operating conditions. The contribution degree of actual pressing force is adjusted based on the magnitude of vehicle deceleration and the deviation between target and actual pressing forces, enabling the system to optimize between reliability and energy efficiency in real-time.
3Measurement precision
If contribution degree of actual pressing force value is increased in region of small operation amount, then resolution of pressing force detection is improved, but contribution degree of estimated pressing force value should be reduced to maintain balance
Solution Approach 1:
The patent changes the parameters (contribution degrees) of the control algorithm based on operating conditions. By adjusting the weighting between actual and estimated pressing force values according to operation amount and deceleration magnitude, the system improves measurement precision in critical regions while managing algorithm complexity through condition-based parameter adaptation rather than complex computational models.
Data Source
AI summary
A vehicle electric braking device wherein: a first degree of contribution associated with the actual pressing force value and a second degree of contribution associated with an estimated pressing force value, are determined based on operation amount of a braking operation member; the second degree of contribution is determined to be larger than the first degree when the operation amount is small; the first degree of contribution is determined to be larger than the second when the operation amount is large; a combined pressing force is calculated based on a value obtained by accounting for the first degree of contribution in the actual pressing force value and a value obtained by accounting for the second degree of contribution in the estimated pressing force value; and an electric motor target power supply amount is calculated based on the combined pressing force and a target pressing force calculated from the operation amount.