Predictive Automatic Hold Activation Timing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional wheel speed sensors provide inaccurate measurements at low vehicle speeds, leading to incorrect activation of the automatic hold function, often resulting in premature or delayed braking, which is inconvenient for the operator.
Innovation Solution
Calculating the future vehicle speed based on present speed and acceleration, and activating the automatic hold function when the future speed falls below a predefined threshold, allowing for precise timing of brake activation before the vehicle comes to a standstill.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wheel speed sensors are used to detect vehicle standstill, then the automatic hold function can be activated, but the measurement accuracy deteriorates at low speeds causing premature or delayed braking
Solution Approach 1:
The system calculates future vehicle speed based on current speed and acceleration measurements, then activates the automatic hold function when this predicted future speed falls below a threshold. This preliminary calculation approach allows the system to anticipate the standstill event and activate braking at the optimal moment, compensating for the inherent delay and inaccuracy of conventional wheel speed sensors at low speeds.
2Reliability
If automatic hold function is activated when vehicle reaches standstill, then the vehicle is held stationary, but activation occurs too late when rolling uphill causing the vehicle to roll back
Solution Approach 1:
The system performs preliminary calculation of future vehicle speed using current kinematic data before the actual standstill occurs. By predicting when the vehicle will reach zero speed, the system can initiate brake activation in advance, ensuring the brake engages precisely at the moment of standstill rather than after the vehicle has already begun rolling back.
Solution Approach 2:
The system dynamically adjusts the activation criterion from a static zero-speed threshold to a dynamic prediction based on current speed and acceleration. This dynamic approach allows the system to adapt to varying deceleration rates and accurately predict the standstill moment, optimizing the timing of automatic hold activation regardless of the vehicle's current state.
3Extent of automation
If automatic hold function is activated based on conventional speed measurement, then the function operates automatically, but the vehicle is braked harshly due to premature activation
Solution Approach 1:
By calculating future vehicle speed and predicting the exact moment of standstill, the system avoids premature activation that would cause harsh braking. The preliminary prediction ensures the automatic hold function activates only at the optimal moment, maintaining smooth and comfortable braking while preserving full automation.
Data Source
AI summary
A method for determining the moment of activation of an automatic hold function in vehicles. The optimum moment of activation may be determined precisely if the present vehicle speed is measured by wheel speed sensors, a future vehicle speed is calculated and the hold function is activated when the calculated future vehicle speed is lower than a predefined speed threshold.