ABS Braking Pressure Control for Smooth Deceleration
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Solution Overview
Problem
Existing ABS braking systems in commercial vehicles experience restless and uncertain braking behavior due to early activation of the ABS control, leading to unpleasant braking experiences, especially at high vehicle deceleration settings.
Innovation Solution
A method for electronically controlling vehicle deceleration by adjusting brake pressures on wheel brakes based on detected actual vehicle deceleration, limiting brake pressure when deceleration exceeds a maximum threshold and increasing it when deceleration is below a minimum threshold, using a maximum and minimum deceleration characteristic curve to maintain smooth braking behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the target differential slip is increased at high vehicle target deceleration to ensure more sensitive transition to ABS control, then the ABS control activates earlier, but the braking behavior becomes more unstable and unsafe
Solution Approach 1:
Instead of increasing the target differential slip at high deceleration to activate ABS earlier, the patent inverts the approach by limiting the brake pressure at the rear axle when actual deceleration exceeds a maximum threshold. This prevents premature ABS activation and maintains stable braking behavior while still ensuring safety through direct deceleration-based control.
Solution Approach 2:
The patent changes the control parameter from differential slip to actual vehicle deceleration. By using a deceleration threshold instead of a slip threshold, the system achieves more predictable and stable braking control, especially at high deceleration levels where differential slip control becomes unstable.
2Reliability
If the brake pressure at rear wheel brakes is limited to prevent premature rear wheel lock-up, then rear wheel lock-up is prevented, but the braking behavior appears unstable due to readjustment above maximum deceleration
Solution Approach 1:
The patent implements dynamic brake pressure control where the maximum deceleration threshold and brake pressure limitation are adjusted based on the current braking state and vehicle conditions. This dynamic adaptation prevents unstable readjustment behavior while maintaining reliable wheel lock-up prevention throughout the braking process.
3Adaptability or versatility
If electronic brake pressure limitation is employed without mechanical position sensor or pressure sensor, then the system can regulate brake pressure based on wheel speed difference, but direct load measurement is not provided reducing control precision
Solution Approach 1:
The system uses readily available wheel speed sensors to infer vehicle load and braking state, rather than requiring additional dedicated load measurement sensors. By analyzing the differential wheel speeds and their changes during braking, the system self-determines the appropriate brake pressure limitation without external load measurement inputs.
Data Source
Figure 1
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Figure 4a~4b
AI summary
The invention relates to a method for controlling a deceleration of a vehicle (200) with an ABS braking system (100), comprising at least the following steps: detecting a setpoint vehicle deceleration predetermined by the driver, determining a maximum deceleration and a minimum deceleration, in each case as a function of the detected setpoint vehicle deceleration, detecting an actual vehicle deceleration and controlling a braking pressure (pHA, pVA) on wheel brakes (5, 6, 7, 8) of a vehicle axle (HA, VA) to be controlled as a function of the detected actual vehicle deceleration by controlling ABS brake valves (11, 12, 13, 14) such that the braking pressure (pHA, pVA) on the wheel brakes (5, 6, 7, 8) of the vehicle axle (HA, VA) to be controlled is increased if the actual vehicle deceleration is smaller than the minimum deceleration for reaching a minimum braking effect, and the braking pressure (pHA, pVA) on the wheel brakes (5, 6, 7, 8) of the vehicle axle (HA, VA) to be controlled is limited if the actual vehicle deceleration is greater than the maximum deceleration for limiting the braking effect of the vehicle axle (HA, VA) to be controlled.