Vehicle Braking Control Device Load-Adaptive Assist Initiation
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Solution Overview
Problem
Existing braking control devices for vehicles fail to appropriately initiate assist control for emergency braking operations, especially when the vehicle is heavily loaded, due to delayed changes in G sensor values, leading to potential failures in starting assist control.
Innovation Solution
A braking control device that calculates both wheel speed and vehicle body deceleration using sensors, with an adjustable initiation time reference value based on the vehicle load, ensuring timely initiation of assist control by setting a larger initiation time when the load is heavy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the initiation time determination reference value is set to a fixed value, then the assist control can be initiated timely under normal conditions, but the assist control fails to initiate under heavy load conditions due to delayed G sensor response
Solution Approach 1:
The initiation time determination reference value is changed from a fixed value to a variable value that dynamically adapts to different vehicle load conditions. The control unit determines the reference value based on detected vehicle parameters (such as vehicle speed, brake pedal depression amount, and wheel deceleration), making the system flexible and adaptable to various operating conditions including heavy load scenarios.
Solution Approach 2:
The patent changes the parameter of initiation time determination reference value from constant to variable. By adjusting this time parameter based on actual vehicle conditions, the system can accommodate different load scenarios. When heavy load is detected (indicated by delayed G sensor response), the reference value is extended to allow sufficient time for the G sensor to respond, ensuring reliable assist control initiation.
2Reliability
If the initiation time determination reference value is extended to accommodate heavy load conditions, then the assist control can be initiated under all load conditions, but the assist control may be delayed under normal light load conditions
Solution Approach 1:
The system dynamically adjusts the initiation time determination reference value based on real-time vehicle conditions rather than using a fixed extended value. By monitoring parameters such as wheel deceleration rate and brake pedal depression characteristics, the control unit determines the appropriate reference value, ensuring timely response under normal conditions while providing extended time when heavy load is detected.
Solution Approach 2:
The initiation time determination reference value is changed from a uniformly extended parameter to a condition-dependent variable parameter. The control unit calculates appropriate reference values based on the relationship between wheel deceleration and G sensor response, allowing the system to optimize response time for each specific operating condition rather than always using a conservative extended time value.
Data Source
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AI summary
A brake ECU acquires the vehicle load (WW) (step S142), and sets a higher start-time criterion value (KT2) when the load (WW) is heavy than when the load (WW) is light (step S144). The brake ECU initiates auxiliary control when the period since the deceleration of the vehicle exceeded a first deceleration determination value is less than or equal to the start-time criterion value (KT2) and the G sensor value exceeds a second deceleration determination value.