Braking Force Control Device with Friction-Adaptive Stop Detection
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Solution Overview
Problem
Existing braking force control methods struggle to accurately determine when a vehicle has stopped on low-friction road surfaces, leading to inappropriate application of holding braking force before the vehicle fully decelerates, which can hinder control and lock release operations.
Innovation Solution
A braking force control method that adjusts the predetermined time for determining vehicle stoppage based on road surface friction, delaying the application of holding braking force on low-friction surfaces to ensure proper deceleration and prevent premature lock engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a braking force is applied to hold the stopped state based on wheel speed alone, then the vehicle can be held stationary, but the braking force may be applied before the vehicle sufficiently decelerates on low-friction surfaces
Solution Approach 1:
The patent changes the parameter of time delay duration based on road surface friction conditions. On low-friction surfaces, a longer time delay is applied before determining the vehicle has stopped, while on high-friction surfaces, a shorter time delay is sufficient. This dynamic parameter adjustment resolves the contradiction by adapting the stop determination criteria to match actual road conditions, preventing premature holding braking force application while maintaining reliable stop detection.
2Device complexity
If a fixed predetermined time is used to determine vehicle stoppage, then the control logic is simple, but it cannot adapt to different road surface friction conditions
Solution Approach 1:
The patent makes the predetermined time delay dynamic rather than fixed. The control unit adjusts the time delay duration based on detected road surface friction conditions - extending the delay on low-friction surfaces and reducing it on high-friction surfaces. This dynamic adaptation maintains relatively simple control logic while significantly improving adaptability to different road conditions, resolving the contradiction between simplicity and versatility.
3Speed
If the predetermined time for stop determination is shortened, then the response speed is faster, but the vehicle may not have sufficiently decelerated on low-friction surfaces
Solution Approach 1:
The patent adjusts the time delay parameter based on road surface friction detection. On low-friction surfaces, the time delay is extended to allow sufficient deceleration time, while on high-friction surfaces, the time delay is shortened for faster response. This conditional parameter adjustment resolves the contradiction by optimizing the response time according to actual road conditions, ensuring both speed and reliability are maintained appropriately for each scenario.
Data Source
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AI summary
A braking force control method detects a wheel speed (w) of a vehicle (1), generates a holding braking force for holding the stopped state of the vehicle (1), regardless of whether or not a brake (3) is operated by a driver of the vehicle (1), when it is determined that the vehicle (1) has stopped, based on the wheel speed (w) detected in the state in which a braking force is applied to the vehicle (1), and delays the period in which the holding braking force is generated, in accordance with the friction coefficient of a road surface in the traveling path of the vehicle (1).