Hill Start Torque Threshold Control for Degraded Sensor Conditions
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Solution Overview
Problem
Current hill start assistance systems for vehicles fail to operate effectively when the signal from the slope sensor is unreliable or when information about the clutch and gear ratio is not available, leading to issues with brake release and maneuvering on slopes.
Innovation Solution
A method that determines a threshold take-off torque independently of the actual slope and gear ratio characteristics, using predefined values in degraded conditions to ensure safe and successful vehicle starting, even without reliable slope sensor data or clutch/gear information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the hill start assistance system uses slope sensor data to determine brake release timing, then the vehicle can start safely on slopes, but the system fails when the slope sensor signal is unreliable or unavailable
Solution Approach 1:
The system pre-determines a default threshold torque value that can be used when slope sensor data is unavailable. This preliminary preparation of fallback parameters allows the system to maintain functionality in degraded conditions without requiring real-time sensor data, resolving the contradiction between reliability and adaptability.
Solution Approach 2:
The control system acts as an intermediary between the slope sensor and the brake release mechanism. When the sensor signal is unreliable, the control system intermediates by substituting the default threshold torque value, allowing the brake release function to continue operating safely without direct dependence on the faulty sensor.
2Productivity
If the system determines brake release based on actual slope and gear ratio characteristics, then optimal performance is achieved, but the system becomes complex and sensitive to sensor failures
Solution Approach 1:
The system changes the parameter used for brake release determination from actual slope/gear ratio characteristics to a default threshold torque value when sensor data is unavailable. This parameter substitution simplifies the system operation in degraded conditions while maintaining safety, reducing the complexity-sensitivity trade-off.
3Speed
If the assisted parking brake releases early based on torque threshold, then the vehicle can start quickly, but the brakes may be damaged on steep slopes
Solution Approach 1:
The system uses feedback from the torque sensor to monitor the actual torque transmitted to the wheels. By comparing real-time torque measurements against the threshold value (whether from slope sensor or default), the system ensures the brake release timing is appropriate for current conditions, preventing both premature release (brake damage) and delayed release (slow take-off).
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables vehicles to start on slopes without damaging the braking system, regardless of slope sensor reliability, and informs the driver of system malfunctions through an unusual torque feel, ensuring the vehicle moves forward without immobilization.
Implementation Method 1
a slope sensor 2... When the vehicle is stopped on a slope, the slope sensor 2 delivers a signal representative of the inclination of the slope
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
The invention relates to a method for assisting with hill manoeuvres for a vehicle, comprising a propulsion unit connected to the drive wheels by means of a gearbox and of a clutch or torque converter, and an assisted parking brake, during which method a threshold breakaway torque is determined as a function of the longitudinal forces between the wheels of the vehicles and the ground, characterized in that, during degraded operation, that is to say when a signal corresponding to the characteristic of the slope is received that cannot be used and/or when the computer does not have available a signal characteristic of the engaged gear ratio, a threshold value for the breakaway torque is determined without taking account of the actual value of the characteristic of the slope and/or of the characteristic of the gear ratio.