Vehicle Speed Estimation Using Vertical and Longitudinal Acceleration Sensors
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Solution Overview
Problem
Existing vehicle speed estimation methods, particularly in automated driving systems, face inaccuracies when using longitudinal acceleration due to gravitational components during uphill or downhill driving, which can lead to unreliable speed calculations in case of catastrophic failures of electronic stability or brake controller modules.
Innovation Solution
The system employs both vertical and longitudinal acceleration sensors to differentiate inertial from gravitational components in longitudinal acceleration, allowing for accurate vehicle speed estimation and enabling safe vehicle control through actuation controllers, even in the event of controller failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If longitudinal acceleration sensors are used for vehicle speed estimation, then the system can provide backup speed information when wheel speed sensors fail, but the speed calculations become inaccurate during uphill or downhill driving due to gravitational components
Solution Approach 1:
The patent segments the longitudinal acceleration measurement into two components: gravitational component (determined by slope angle from vertical acceleration sensor) and inertial component (actual vehicle acceleration). By separating these components, the system can accurately calculate vehicle speed from the inertial component while compensating for gravitational effects using the vertical acceleration sensor data.
Solution Approach 2:
The vertical acceleration sensor acts as an intermediary that provides slope angle information. This intermediary data allows the system to calculate and remove the gravitational component from the longitudinal acceleration measurement, thereby enabling accurate speed estimation even on inclined surfaces.
2Measurement precision
If the system uses multiple sensors (vertical and longitudinal acceleration sensors) to differentiate inertial from gravitational components, then measurement precision improves, but device complexity increases
Solution Approach 1:
The vertical acceleration sensor serves multiple functions: it detects vertical acceleration for safety monitoring and simultaneously provides slope angle information for gravitational component compensation in speed calculation. This multi-functionality reduces the need for additional dedicated sensors, thereby limiting the increase in device complexity while maintaining high measurement precision.
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 provides reliable vehicle speed calculations and safe deceleration control by accurately accounting for gravitational influences, ensuring vehicle safety during automated driving, especially in scenarios where primary speed sensors are unavailable.
Implementation Method 1
vertical acceleration sensor to sense a vertical acceleration of the vehicle... to differentiate inertial from gravitational components in longitudinal acceleration
Implementation Method 2
longitudinal acceleration sensor to sense a longitudinal acceleration of the vehicle... determining a second vehicle speed using the vertical acceleration and the longitudinal acceleration
Data Source
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AI summary
System and method for determining vehicle speed of a wheel. The system including an electronic stability controller, an occupancy restraint controller, and an actuation controller coupled to a communication bus. The electronic stability controller including a wheel speed sensor to determine a first vehicle speed. The occupancy restraint controller including a vertical acceleration sensor to sense a vertical acceleration of the vehicle and a longitudinal acceleration sensor to sense a longitudinal acceleration of the vehicle. The actuation controller configured to determine a second vehicle speed using the vertical acceleration and the longitudinal acceleration of the vehicle, validate the second vehicle speed when the difference between the first vehicle speed and the second vehicle speed is less than a threshold, and use the first vehicle speed when the difference between the first vehicle and the second vehicle speed is greater than a threshold.