Hydraulic Braking Efficiency Estimation for Predictable Deceleration
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Solution Overview
Problem
The existing braking control methods for vehicles with regenerative and hydraulic braking systems are inefficient, leading to unpredictable deceleration due to the inaccuracy of hydraulic actuators and varying efficiency over time, causing discomfort for users and requiring cumbersome measurement processes.
Innovation Solution
A method that estimates the efficiency coefficient of hydraulic braking by measuring vehicle acceleration and torque variations during braking transitions, allowing for independent choice of measurement instants and accounting for external dynamics, enabling better user comfort and maintenance through adaptive setpoint correction and wear detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If hydraulic braking is used to complement regenerative braking, then braking coverage at low speeds is improved, but braking predictability deteriorates due to efficiency variations
Solution Approach 1:
The system continuously measures actual vehicle deceleration and compares it with the commanded deceleration to calculate a correction factor. This feedback loop compensates for hydraulic actuator efficiency variations by adjusting the braking distribution in real-time, thereby maintaining braking predictability while using hydraulic braking to extend coverage to low speeds.
Solution Approach 2:
The system dynamically adjusts the distribution parameter between regenerative and hydraulic braking based on calculated efficiency ratios. By changing the control parameters (braking torque allocation) according to measured performance, the system optimizes braking coverage across different speed ranges while compensating for hydraulic system variations.
2Reliability
If regenerative braking is deactivated below 7 km/h, then mechanical braking reliability is improved, but energy recovery efficiency deteriorates
Solution Approach 1:
Instead of completely deactivating regenerative braking below 7 km/h, the system applies partial regenerative braking in conjunction with hydraulic braking. This partial action approach allows continued energy recovery while using hydraulic braking to compensate for the reduced regenerative contribution, thereby reducing energy loss without compromising mechanical braking reliability.
3Manufacturing precision
If hydraulic braking efficiency is corrected in real-time, then braking precision is improved, but control system complexity increases
Solution Approach 1:
The system uses the vehicle's existing sensors (accelerometers, speed sensors) and onboard processing capabilities to perform self-diagnosis and self-correction of braking efficiency. By leveraging already-available components for the correction function, the system achieves improved braking precision without significantly increasing overall control system complexity.
4Reliability
If the distribution system prohibits electric braking below 7 km/h, then hydraulic braking reliability is improved, but overall braking efficiency deteriorates
Solution Approach 1:
The system dynamically determines the switching point between purely hydraulic and combined braking modes based on real-time conditions rather than using a fixed speed threshold. This dynamic adaptation allows the system to maintain hydraulic braking reliability when needed while optimizing overall braking efficiency by utilizing regenerative braking whenever conditions permit.
Data Source
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Figure 2b
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AI summary
The invention relates to a method for a vehicle provided with a regenerating braking means and a complementary braking means, including: receiving (20) at least one vehicle acceleration measurement value, at least one torque value applied by the regenerating braking system, and at least one complementary braking set value for the complementary braking means, wherein said at least one value corresponds to at least one respective measurement moment during a braking transition; and estimating (25) the efficiency coefficient of the complementary braking means from said at least one received value.