Hill Hold Assistant Dynamic Torque Threshold
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Solution Overview
Problem
Existing driver assistance systems for starting on an incline prematurely release the brake due to electrical consumers increasing engine torque, causing the vehicle to roll back before sufficient drive torque is reached.
Innovation Solution
Adjusting the engine torque or speed threshold condition to account for changes not caused by the accelerator pedal, ensuring the brake is only released when the drive torque compensates for downhill force, by monitoring electrical consumers and adjusting the release condition accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the brake release condition is set to a fixed engine torque threshold, then the system is simple to operate, but the brake is released too early when electrical consumers are active, causing vehicle rollback
Solution Approach 1:
The brake release threshold is made dynamic by adjusting it based on the operating state of electrical consumers. When electrical consumers are active, the threshold is increased to account for the additional engine torque they consume, ensuring the brake is only released when sufficient drive torque is actually available at the wheels.
Solution Approach 2:
The system monitors the operating state of electrical consumers and uses this feedback to adjust the brake release condition. The control unit continuously checks whether electrical consumers are active and modifies the torque threshold accordingly, creating a closed-loop control system that adapts to changing conditions.
2Reliability
If the engine torque threshold is increased to prevent rollback, then the vehicle will not roll back, but the brake is released too late even when sufficient drive torque is available
Solution Approach 1:
The system applies different threshold values for different operating conditions. Instead of using a single global threshold, it locally adapts the threshold based on whether electrical consumers are active, allowing optimal brake release timing for each specific situation.
Solution Approach 2:
The system changes the torque threshold parameter dynamically based on the operating state of electrical consumers. When consumers are active, the threshold is raised; when they are inactive, the threshold returns to its original value, optimizing both reliability and response time.
3Productivity
If the brake is released when engine torque exceeds a fixed threshold, then the system responds quickly to driver input, but electrical consumers cause premature brake release and vehicle rollback
Solution Approach 1:
The system performs preliminary monitoring of electrical consumer states and pre-calculates the appropriate threshold value before the brake release decision is made. This allows the system to respond quickly when the brake release condition is met, while already having the correct threshold ready based on the current electrical load.
Data Source
Figure 1
Figure 2~3
AI summary
The invention relates to a method for assisting a driver during hill start, the vehicle being automatically maintained stationary by means of a brake (8) and the brake (8) being automatically released when the driver's intention to start the vehicle is detected, provided that the engine torque (14) or a variable proportional thereto exceeds a predetermined threshold value (13). The vehicle can be prevented from rolling back when the brake is released by monitoring the engine torque (14) or the equivalent variable for a change that is not due to the actuation of the accelerator (4) and by modifying the condition for releasing the brake (8) when a change in engine torque (14) or the equivalent variable is detected.