Vehicle Braking Distance Estimation Using Segment Friction Data
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for determining braking distance estimates are not accurate enough, as they do not effectively utilize detailed and up-to-date friction information, which is crucial for predicting the distance required to reduce a vehicle's speed to a target speed while activating the braking system.
Innovation Solution
A method that receives segment-specific friction information for multiple trajectory segments ahead of the vehicle, calculates segment end speeds using energy balances, and determines the braking distance estimate as the sum of segment lengths where the vehicle exceeds the target speed, incorporating intra-segment length calculations and considering friction uncertainty to provide a reliable estimate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If segment-specific friction information is received for multiple trajectory segments and used in calculations, then the accuracy of braking distance estimates is improved, but the device complexity and computational requirements increase
Solution Approach 1:
The trajectory ahead of the vehicle is divided into multiple discrete trajectory segments, each with its own friction coefficient. This segmentation allows the system to process friction information in manageable units while maintaining high accuracy across the entire braking distance calculation, resolving the contradiction between detailed analysis and system complexity.
Solution Approach 2:
Each trajectory segment is assigned a local friction coefficient specific to that segment's road conditions, rather than using a single global friction value. This local quality approach enables precise braking distance estimation for each segment while the modular structure keeps overall system complexity manageable.
2Reliability
If detailed friction information for multiple trajectory segments is processed, then the reliability of braking distance estimates is improved, but the loss of time for data processing increases
Solution Approach 1:
Friction information for multiple trajectory segments is received and stored in advance, before the actual braking maneuver is needed. This preliminary action allows the system to have friction data ready for immediate use, improving reliability without adding processing delays during critical braking situations.
Solution Approach 2:
The patent replaces complex iterative mechanical calculations with energy balance equations that provide direct solutions. By substituting the traditional step-by-step mechanical analysis with energy conservation principles, the system achieves high reliability results more efficiently, reducing processing time.
3Measurement precision
If friction uncertainty is considered in the calculations, then the measurement precision of braking distance estimates is improved, but the computational complexity increases
Solution Approach 1:
The system incorporates friction uncertainty by treating the friction coefficient as a parameter with associated uncertainty bounds rather than a fixed value. This parameter change approach allows the calculation to account for variability and improve precision while maintaining a relatively simple computational framework based on energy balance equations.
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
This approach significantly improves the accuracy of braking distance estimates by using detailed friction information, maintaining high accuracy even with changing conditions, and reduces uncertainty, thereby enhancing travel safety by enabling precise speed adjustments and collision avoidance.
Implementation Method 1
friction between the wheels of the vehicle which are coupled to the braking system and the roadway has an important influence on the braking distance
Data Source
Figure 1~2
Figure 3
AI summary
The disclosure relates to a method for determining a braking distance estimate (D) for a vehicle (10) travelling along a trajectory (T) on a roadway (R) at a known current vehicle speed (Vo). The braking distance estimate (D) is an estimate of a distance along the trajectory (T) needed by the vehicle (10) for reducing the current vehicle speed (Vo) to a target vehicle speed (VT) while a braking system is activated. The method comprises receiving a friction information (F1, F2, ..., FN) for each of a plurality of trajectory segments (T1, T2, ..., TN) lying ahead of the vehicle (10) and calculating a segment end speed (V1, V2, ..., VN) for each trajectory segment (T1, T2, ..., TN) until for an end segment (TE) a segment end speed (VE) is determined which equals the target vehicle speed (VT) or is lower than the target vehicle speed (VT). Furthermore, an intra-segment length (liE) within the end segment (TE) is determined. The braking distance estimate (D) is determined as the sum of the lengths (l1, l2, .., lE-1) of the trajectory segments (T1, T2, ..., TE-1) having a segment end speed (V1, V2, ..., VE-1) exceeding the target vehicle speed (VT) and the intra-segment length (liE). Additionally, a method for operating a driver assistance system (12) of a vehicle (10) is presented. Moreover, a data processing apparatus (14, 28) and a computer program (22, 36) are explained.