Vehicle Brake Control Switching Without Longitudinal Acceleration Sensor
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In hybrid vehicles, the failure of the longitudinal acceleration sensor can hinder the switching from regenerative cooperation control to hydraulic pressure control during braking, leading to difficulties in preventing cascade locking of all four wheels.
Innovation Solution
A vehicle brake hydraulic pressure control apparatus that calculates vehicle body deceleration independently using wheel speed and lateral acceleration, and considers road inclination, allowing for accurate switching from regenerative cooperation control to hydraulic pressure control without relying on the longitudinal acceleration sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the longitudinal acceleration sensor is used to calculate vehicle body velocity for determining slip rate, then the switching from regenerative cooperation control to hydraulic pressure control can be achieved, but the system reliability deteriorates when the sensor fails
Solution Approach 1:
The patent introduces wheel speed as an intermediary parameter to calculate vehicle body velocity when the longitudinal acceleration sensor is unavailable. The wheel speed data from wheel speed sensors serves as a mediator to maintain the slip rate calculation and control switching functionality, ensuring system reliability without direct dependency on the acceleration sensor.
Solution Approach 2:
The system performs preliminary detection of sensor abnormalities and prepares alternative calculation methods in advance. When the longitudinal acceleration sensor is detected to be abnormal, the control unit automatically switches to using wheel speed data for velocity calculation, ensuring continuous operational reliability without interruption.
2Ease of operation
If the slip rate calculation depends on the longitudinal acceleration sensor output, then the control switching can be performed, but the ease of operation deteriorates when sensor failure occurs
Solution Approach 1:
The patent changes the input parameter for velocity calculation from longitudinal acceleration sensor output to wheel speed sensor output. This parameter substitution allows the control switching operation to proceed normally even when the original sensor fails, maintaining ease of operation while reducing sensor dependency.
3Measurement precision
If only wheel speed is used to calculate slip rate, then the device complexity is reduced, but the measurement precision deteriorates due to inability to account for vehicle body deceleration
Solution Approach 1:
The patent makes the wheel speed data serve multiple functions: it is used both for direct slip rate calculation and for deriving vehicle body velocity when acceleration sensor data is unavailable. This multi-functional use of existing wheel speed measurements improves measurement precision without adding new sensors or significantly increasing device complexity.
Data Source
AI summary
A vehicle brake hydraulic pressure control apparatus includes a wheel speed acquiring section, a vehicle body deceleration calculator, and a switch section. The wheel speed acquiring section is configured to acquire a wheel speed from a wheel speed sensor. The vehicle body deceleration calculator is configured to calculate a vehicle body deceleration. The switch section is configured to switch control from the regenerative cooperation control to the hydraulic pressure control, based on (i) a wheel deceleration which is determined based on the wheel speed and (ii) the vehicle body deceleration. The vehicle body deceleration calculator is configured to calculate the vehicle body deceleration based on a required deceleration which corresponds to a driver's operation of a braking pedal.