Gradual Brake Force Reduction for Hill Start Rollback Prevention
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Solution Overview
Problem
Existing systems for supporting motor vehicle starting on inclined routes can lead to uncontrolled downhill movement when driver-independent hill holding functions end, potentially causing damage and loss of vehicle control due to abrupt brake release.
Innovation Solution
A method that gradually reduces the brake force holding a motor vehicle at a standstill on an inclined route and independently controls its movement according to a preset course, detecting and responding to abortion conditions such as system faults or driver attempts to leave the vehicle, ensuring a controlled and safe transition from standstill to motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the brake force is maintained independently of the driver for a predetermined holding time, then the motor vehicle can be held at a standstill on an inclined route, but the motor vehicle may begin to roll downhill in an uncontrolled manner when the brake force is abruptly withdrawn
Solution Approach 1:
The brake force is dynamically adjusted from a held constant value to a gradually reducing value over time. The system transitions from maintaining a static brake force during the holding period to dynamically reducing the brake force in controlled steps, allowing the vehicle to move from standstill to motion in a controlled manner rather than experiencing abrupt release.
Solution Approach 2:
The system performs preliminary action by maintaining the brake force independently of the driver during a predetermined holding time before the driver needs to react. This preliminary holding phase ensures the vehicle remains stationary on the incline long enough for the driver to prepare for starting, preventing premature rollback before the driver can engage the clutch or press the accelerator.
2Ease of operation
If the brake force is gradually reduced to put the motor vehicle into motion, then the transition from standstill to motion is smooth and controlled, but the holding time is extended beyond the predetermined duration
Solution Approach 1:
The system applies partial action by gradually reducing the brake force in controlled steps rather than maintaining full brake force throughout the entire transition period. The brake force is partially reduced over time to allow controlled motion, balancing the need for vehicle control with the requirement to eventually release the brake and allow the vehicle to move freely once started.
3Extent of automation
If the brake force is maintained independently of the driver, then driver-independent support is provided for starting on an inclined route, but the driver may be taken by surprise by abrupt release of brake actuation
Solution Approach 1:
The system incorporates feedback by continuously monitoring the driver's starting actions (clutch engagement, accelerator pressing) and adjusting the brake force reduction accordingly. The automatic brake release is triggered only when the system detects that the driver has initiated starting maneuvers, ensuring the driver is aware of and in control of the vehicle's movement while still benefiting from automated hill holding support.
Data Source
AI summary
A method for starting a motor vehicle, which is held at a standstill on an inclined route by a brake force which is maintained independently of the driver, after a predetermined holding time has elapsed gradually reduces the brake force which is generated independently of the driver, to put the motor vehicle into motion, and then controls the movement of the motor vehicle, corresponding to a preset course.