Vehicle Braking Control Device for Comfortable Stops
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Solution Overview
Problem
Existing braking control devices apply excessive brake pressure due to errors in road surface gradient estimation, leading to uncomfortable vehicle stops and increased actuation time and frequency, as they assume worst-case parameters based on sensor data with potential variations and aging issues.
Innovation Solution
A braking control device with a stopping braking force imparting unit, deviation quantity deriving unit, and stopping braking force updating unit optimizes the braking force by learning from the deviation between actual and ideal state quantities, ensuring the minimum braking force required to maintain a stop state is applied.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the target holding pressure is set higher based on worst-case assumptions to ensure stopping reliability, then the reliability of stopping is improved, but the braking force becomes excessive causing passenger discomfort and increased actuation time
Solution Approach 1:
The system uses feedback from acceleration sensors and wheel speed sensors to monitor actual vehicle deceleration and stop state. The control unit compares actual deceleration with target deceleration and adjusts the brake pressure accordingly, reducing unnecessary braking force while maintaining reliable stopping. This feedback mechanism eliminates the need for overly conservative worst-case pressure settings.
Solution Approach 2:
The system dynamically changes the target holding pressure parameter based on real-time sensor data including actual road gradient, vehicle weight, and environmental conditions. Instead of using fixed worst-case values, the control unit adjusts pressure parameters adaptively, optimizing the balance between stopping reliability and passenger comfort for each specific situation.
2Reliability
If the target holding pressure is set higher to account for sensor errors and parameter variations, then the reliability is improved, but the actuation time and actuation frequency increase
Solution Approach 1:
The control unit continuously monitors wheel speed and acceleration to detect the stop state in real-time. When the vehicle reaches the stop state, the system immediately adjusts brake pressure to the optimal holding level based on actual conditions rather than maintaining high worst-case pressure throughout, reducing unnecessary actuation time.
Solution Approach 2:
The system transitions from static worst-case pressure settings to dynamic pressure adjustment based on real-time vehicle state. The control unit modifies brake pressure continuously during the stopping process and maintains optimal pressure during the stop state, adapting to changing conditions without unnecessary delays.
3Adaptability or versatility
If the target holding pressure is set based on acquired road surface gradient and estimated stop duration, then the braking control is adapted to conditions, but errors in sensor performance and parameter estimation cause excessive brake pressure
Solution Approach 1:
The system uses feedback from acceleration sensors and wheel speed sensors to verify and correct the estimated road gradient and stop duration. The control unit compares actual vehicle behavior with predictions based on sensor data and adjusts the target holding pressure accordingly, compensating for measurement errors in real-time.
Solution Approach 2:
The system initially applies brake pressure based on worst-case assumptions but then reduces the pressure to the actual required level once the stop state is confirmed through sensor feedback. This partial action approach ensures sufficient initial braking force while eliminating excessive pressure maintenance during the stop state.
Data Source
AI summary
A control device is applied to a vehicle that has a braking device configured to be able to adjust the braking force applied to the vehicle. The control device has a stopping braking force imparting unit that controls the braking device in order to apply a stopping braking force to the vehicle, as a minimum value of the braking force required to keep the vehicle stopped. The control device also has a deviation quantity deriving unit that derives a deviation quantity between a state quantity of the vehicle obtained when the stopping braking force is applied to the vehicle by the stopping braking force imparting unit and an ideal value of the state quantity of the vehicle. The control device also has a stopping braking force updating unit that updates the stopping braking force on the basis of the deviation quantity derived by the deviation quantity deriving unit.