Vehicle Speed Determination Using Segmented Wheel Sensor Logic
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Solution Overview
Problem
Current longitudinal control systems and distance-related longitudinal control systems face challenges in accurately determining vehicle speed, especially at low speeds and standstill positions, leading to imprecise detection and potential jolts during vehicle stoppages.
Innovation Solution
A method that determines vehicle speed by calculating a provisional first speed value for high speeds and a provisional second speed value for low speeds, using a combination of wheel speed sensors and status signals to accurately detect standstill positions and movement directions, with a weighting factor to combine these values for precise speed determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the average wheel speed of non-powered wheels is used to determine vehicle speed, then the system is simple and adequate for speeds above 30 km/h, but the detection precision deteriorates at low speeds and standstill positions
Solution Approach 1:
The speed determination method is segmented into multiple ranges: a first speed range (higher speeds) using average wheel speed of non-powered wheels, and a second speed range (lower speeds) using average wheel speed of all wheels. The system transitions between these segments based on the current speed, allowing simple measurement at high speeds and precise measurement at low speeds without requiring complex systems across the entire speed range.
2Ease of operation
If a single threshold method is used for standstill detection, then the system is simple to operate, but the reliability deteriorates due to premature or imprecise standstill detection
Solution Approach 1:
The standstill detection system dynamically adapts the threshold based on vehicle speed. At higher speeds, a first threshold is used, while at lower speeds, a second (different) threshold is applied. This dynamic adjustment ensures reliable standstill detection across all speed conditions without requiring overly complex static thresholding logic, maintaining ease of operation while improving reliability.
3Productivity
If the vehicle speed determination system is optimized for high speeds, then the productivity is high for cruising conditions, but the measurement precision deteriorates at low speeds and during stop-and-go operations
Solution Approach 1:
The speed determination system is designed with multi-functionality to handle diverse operating conditions. It can determine vehicle speed using different methods depending on the operating regime: using non-powered wheel speeds for high-speed cruising (maintaining productivity) and using all wheel speeds for low-speed and standstill conditions (ensuring precision). This universal approach allows the system to adapt its measurement strategy to maintain both productivity and precision across all speed ranges.
Data Source
AI summary
The invention relates to a method for determining the vehicle speed of a motor vehicle, wherein a provisional first speed value is determined for high speeds and a provisional second speed value is determined for low speeds and the vehicle speed is determined as a function of the determined provisional first speed value either from the provisional first speed value or from the provisional second speed value, or from a combination of the first and second speed values.