Steer-by-Wire Vibration Filtering for Steering Feel
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Solution Overview
Problem
In Steer-By-Wire (SBW) systems, the vibration from road surface interactions is not effectively transmitted to the driver, leading to a lack of steering feeling and decreased performance.
Innovation Solution
A vehicle control system that filters and processes the ground reaction force signals to selectively transmit only necessary vibrations to the steering wheel, using band-pass filtering and mode-specific calculations to differentiate between relevant and irrelevant vibrations based on vehicle conditions such as braking, speed, and travel mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the control amount of the reaction force motor is calculated in consideration of the vibration component included in the ground reaction force, then the driver is given an appropriate steering feeling, but the unnecessary vibration component is transmitted to the steering wheel which may lower steering performance or cause driver anxiety
Solution Approach 1:
The patent extracts only the necessary vibration components from the ground reaction force by applying frequency-based filtering. The controller separates the ground reaction force signal into different frequency bands and selectively transmits only those components that provide useful steering feedback while blocking unnecessary vibrations, thereby resolving the contradiction between providing steering feeling and avoiding harmful vibrations.
Solution Approach 2:
The patent applies different quality characteristics to different frequency components of the vibration signal. By assigning different transmission characteristics to different frequency bands (e.g., transmitting low-frequency components while blocking high-frequency components), the system provides appropriate steering feeling for relevant vibrations while suppressing unnecessary ones, thus resolving the contradiction.
2Loss of information
If all vibration components from ground reaction force are transmitted to the steering wheel, then the driver obtains complete steering feedback, but the driver may be anxious or steering performance may be lowered due to unnecessary vibrations
Solution Approach 1:
The controller extracts only the essential vibration information from the ground reaction force by frequency filtering. This allows the system to maintain complete useful steering feedback while removing unnecessary vibration components that would cause driver anxiety or performance degradation.
Solution Approach 2:
The patent changes the frequency parameter characteristics of the transmitted vibration signal. By modifying which frequency components are transmitted (changing the spectral composition), the system preserves essential steering feedback information while eliminating harmful high-frequency vibrations that would otherwise be transmitted.
3Stability of the object's composition
If the SBW system completely cuts off vibration from the road surface, then the steering system is stable and controlled, but the driver cannot obtain reasonable steering feeling for the ground reaction force
Solution Approach 1:
The patent applies different transmission characteristics to different frequency components, allowing low-frequency vibration components that provide useful steering feeling to pass through while maintaining stability by blocking high-frequency components. This resolves the contradiction between system stability and steering feeling.
Solution Approach 2:
The system dynamically adjusts the vibration transmission characteristics based on driving conditions. The controller calculates the control amount of the reaction force motor considering vehicle speed and other parameters, enabling the system to provide appropriate steering feeling while maintaining stability across different operating conditions.
Data Source
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AI summary
The steer-by-wire system (100) includes a steering device (40), a reaction force device (30), and a controller (50). The steering device (40) turns wheels (70) of a vehicle. The reaction force device (30) applies a steering reaction force to a steering wheel (10). The controller (50) is configured to control the steering reaction force by drive control of the reaction force device (30) in response to an operation of the steering wheel (10). The controller (50) is further configured to: obtain a signal including a component due to a reaction force which acts on the wheels (70) from a road surface; extract a signal being greater than or equal to a predetermined frequency from the signal including the component due to the reaction force; and calculate a control amount of the reaction force device based on the extracted signal equal to or greater than the predetermined frequency.