Rear Wheel Speed Evaluation From Front Wheels During Corner Braking
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for determining the ground travel speed of rear wheels in automobiles are unreliable, especially during lock or skid conditions, and can fail due to sensor damage, making direct measurement impossible.
Innovation Solution
A module evaluates the rear wheel speed indirectly using the speeds of the front wheels through the formula VeAR = (Vmoy^3 + 2*Vmin^2*Vmax)*Kcorr, where Vmoy is the average front wheel speed, Vmin and Vmax are the minimum and maximum front wheel speeds, and Kcorr is a correction coefficient that adjusts based on the ratio of Vmax to Vmin, allowing accurate speed evaluation even in tight bends.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If direct measurement of rear wheel speed is used, then measurement accuracy is improved, but reliability deteriorates during lock or skid conditions or sensor failure
Solution Approach 1:
The patent uses front wheel speed measurements as an intermediary to indirectly determine rear wheel speed. Instead of directly measuring rear wheel speed (which fails during lock/skid), the system measures front wheel speeds and uses a mathematical model to calculate the corresponding rear wheel speed, thereby maintaining reliability under adverse conditions
Solution Approach 2:
The patent replaces the mechanical/direct measurement system (rear wheel speed sensor) with a computational system that uses front wheel speed data and geometric relationships to calculate rear wheel speed, eliminating the single point of failure associated with direct rear wheel sensing
2Reliability
If front wheel speeds are used to evaluate rear wheel speed, then reliability is improved, but measurement precision may deteriorate due to indirect calculation
Solution Approach 1:
The patent adjusts the evaluation parameters by introducing a correction coefficient Kcorr that modifies the calculated rear wheel speed based on the ratio of front wheel speeds. This parameter adjustment compensates for the inherent inaccuracies in indirect measurement, maintaining precision while preserving the reliability benefits of the indirect method
Solution Approach 2:
The system uses feedback from front wheel speed measurements to continuously refine the rear wheel speed evaluation. The correction coefficient is dynamically adjusted based on the ratio of front wheel speeds, creating a feedback mechanism that maintains accuracy despite the indirect measurement approach
3Device complexity
If a simple average of front wheel speeds is used, then device complexity is reduced, but accuracy deteriorates in tight bends
Solution Approach 1:
The patent enhances the simple average calculation by introducing a correction coefficient Kcorr that depends on the ratio of front wheel speeds (Vmax/Vmin). This parameter change accounts for the differential speeds experienced during turning, significantly improving accuracy in tight bends while adding only moderate computational complexity
Solution Approach 2:
The system transitions from a static average calculation to a dynamic calculation that adapts to turning conditions. The correction coefficient is dynamically adjusted based on the front wheel speed ratio, allowing the system to automatically compensate for turning effects without requiring complex geometric modeling
Data Source
AI summary
An evaluation of the speed of movement of a rear wheel of a motor vehicle on the ground, in particular on the inside of a bend, is made exclusively according to the speeds of the front wheels, in situations in which a direct measurement is not possible or in order to accurately evaluate occurrences of wheel lock-up or wheel slip. The invention can be applied to improving the braking setpoints when cornering.