Vehicle Brake Controller Wheel Lock Detection
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Solution Overview
Problem
Conventional vehicle brake hydraulic controllers using acceleration sensors can lead to erroneous ABS control interference on high-μ roads if the acceleration sensor output is fixed, causing incorrect determination of vehicle deceleration and potential wheel lock conditions.
Innovation Solution
A vehicle brake hydraulic controller that calculates wheel deceleration based on wheel speed and uses correction factors to offset acceleration sensor values, determining locking tendencies by comparing vehicle velocity and wheel speed, and adjusting these corrections based on brake pedal operation and road surface conditions to prevent ABS control errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the acceleration sensor value is used directly to calculate vehicle deceleration, then the vehicle velocity calculation is simple, but erroneous ABS control interference occurs on high-μ roads when the acceleration sensor output is fixed
Solution Approach 1:
The patent changes the parameter of vehicle deceleration calculation by introducing a correction amount that is added to the acceleration sensor value. This correction amount is determined based on wheel deceleration and brake pedal operation amount, transforming the single-parameter calculation into a multi-parameter correction system that adapts to different road conditions and prevents erroneous ABS control interference
Solution Approach 2:
The patent implements a feedback mechanism where the calculated wheel deceleration and brake pedal operation amount are used to determine the correction amount, which then feeds back into the vehicle deceleration calculation. This closed-loop feedback system continuously adjusts the vehicle velocity calculation to maintain accuracy and prevent false ABS control activation
2Reliability
If a large correction amount is applied to the acceleration sensor value, then erroneous ABS control interference is suppressed on high-μ roads, but cascade locking may occur when brake pedal operation amount is small and wheel deceleration is large
Solution Approach 1:
The patent makes the correction amount dynamic rather than fixed, adjusting it in real-time based on the brake pedal operation amount and wheel deceleration. When brake pedal operation is small and wheel deceleration is large (conditions favoring cascade locking), the correction amount is reduced appropriately, allowing the system to adaptively prevent cascade locking while maintaining reliability on high-μ roads
3Object-affected harmful factors
If the first correction amount is set to a small value to prevent cascade locking, then wheel lock detection remains sensitive, but erroneous ABS control interference cannot be suppressed on high-μ roads
Solution Approach 1:
The patent changes the correction amount parameter dynamically based on operating conditions. On high-μ roads where erroneous ABS control is a risk, the correction amount is increased to suppress false lock detection. In conditions where cascade locking is likely (small brake pedal operation, large wheel deceleration), the correction amount is decreased to maintain sensitive wheel lock detection, thus resolving the contradiction through conditional parameter adjustment
Data Source
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AI summary
One embodiment provides a vehicle brake hydraulic controller including a wheel speed acquiring section; a wheel deceleration calculator; a vehicle velocity calculator; and a locking tendency determination section. The vehicle velocity calculator calculates a vehicle deceleration based on a temporary vehicle deceleration corresponding to an acceleration sensor value and calculates a vehicle velocity based on the calculated vehicle deceleration. The vehicle velocity calculator calculates the temporary vehicle deceleration by offsetting a first correction amount to a deceleration side in relation to the acceleration sensor value. When a brake pedal operation amount by a driver is equal to or smaller than a first threshold and that an absolute value of the wheel deceleration is equal to or larger than an absolute value of a second threshold are met, the first correction amount is set to be smaller than when the conditions are not met.