Brake Pressure Control Unit Transition Logic
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Solution Overview
Problem
Existing brake systems for motor vehicles experience unpleasant jerking or sudden under-braking when transitioning from external brake control mode to normal braking mode, leading to inconsistent braking behavior and potential safety risks.
Innovation Solution
A method for adjusting brake pressures in pneumatically operated wheel brakes that involves setting a threshold value for the control unit to compare with the driver's brake request, ensuring smooth transition from pressure control mode to normal braking mode by maintaining control unit intervention until the driver's brake request exceeds the threshold or a predefined duration has passed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the control unit immediately terminates pressure control mode when an external brake request is revoked, then the response time is reduced, but the braking behavior becomes inconsistent causing jerking or sudden under-braking
Solution Approach 1:
The control unit determines in advance whether to terminate pressure control mode by checking if a driver brake request is present before actually terminating the mode. This preliminary check ensures that the transition from pressure control mode to normal braking mode only occurs when appropriate, preventing inconsistent braking behavior while maintaining timely response to external brake request revocation
2Reliability
If the control unit maintains pressure control mode until driver brake request exceeds threshold, then braking consistency is improved, but the transition time is extended
Solution Approach 1:
The control unit dynamically adjusts the termination condition of pressure control mode based on the presence and magnitude of driver brake requests. By using a threshold value comparison, the system adaptively determines when to terminate pressure control mode, balancing braking consistency with timely transition. The threshold acts as a dynamic criterion that ensures smooth handover of brake control from the external system to the driver
Data Source
AI summary
A method for adjusting brake pressures on pneumatically operated wheel brakes of a motor vehicle includes setting, in a normal braking mode, a brake pressure depending on a driver brake request determined by the driver of the motor vehicle and a control unit, during reception of an external brake request which is independent of the driver brake request, in a pressure control mode, sets a resulting brake pressure at the respective wheel brakes taking into account the external brake request and the driver brake request. The method further includes terminating, after revocation of the external brake request, the pressure control mode depending on a comparison of a value representing the driver brake request and entered into the control unit with a predefined threshold value.