Steer-by-Wire Steering Wheel Synchronization After Automated Driving
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Solution Overview
Problem
In steer-by-wire vehicles, there is a need for an efficient method to synchronize the steering wheel position with the steering gear after decoupling, especially during transitions from automated to manual control, without requiring mechanical connections or clock springs, while maintaining driver-friendly button placement and minimizing architectural modifications.
Innovation Solution
A method involving a force-feedback actuator to generate hand torque, using wireless energy and signal transmission, and a control unit to determine and execute steering wheel rotations based on predetermined steering angle periods, ensuring synchronization without mechanical connections, and allowing for n-fold rotational symmetry of the steering wheel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If wireless energy and signal transmission is used to eliminate the clock spring, then the steering wheel can be rotated any number of times without mechanical constraints, but position synchronization becomes necessary after automated driving modes
Solution Approach 1:
The patent replaces the mechanical clock spring connection with wireless energy and signal transmission, allowing the steering wheel to rotate freely without mechanical constraints. This substitution eliminates the need for mechanical end stops and allows unlimited rotations, but introduces the need for electronic position synchronization systems to maintain reference after automated driving modes.
2Reliability
If the steering wheel position is synchronized to the current wheel angle, then the steering reference is restored, but the steering wheel may need to rotate a large angle causing buttons to move out of reach
Solution Approach 1:
The patent applies preliminary action by rotating the steering wheel buttons together with the steering wheel during the synchronization process. This ensures that buttons remain in their original positions relative to the driver throughout the rotation, maintaining accessibility and ergonomics while restoring the steering reference.
Solution Approach 2:
The patent uses an intermediary mechanism where the steering wheel buttons are mechanically coupled to rotate with the steering wheel. This intermediary connection ensures that button positions are maintained relative to the driver during the synchronization rotation, solving the conflict between reference restoration and button accessibility.
3Reliability
If the wheel angle is adjusted to match the steering wheel angle, then synchronization is achieved, but the steered wheels may end up in an inconvenient position
Solution Approach 1:
The patent applies the inversion principle by reversing the traditional synchronization approach. Instead of rotating the steering wheel to match the wheel angle, the system adjusts the steered wheel position to correspond to the current steering wheel angle. This inversion ensures that the steering wheel remains in the driver's comfortable position while achieving accurate position synchronization.
4Ease of operation
If rotating buttons are used to maintain button reachability, then ergonomics are preserved, but the steering wheel architecture becomes more complex
Solution Approach 1:
The patent merges the button rotation mechanism with the steering wheel rotation itself. The buttons are integrated into the steering wheel structure and rotate together with it, eliminating the need for separate adjustable button mechanisms. This merging maintains ergonomics while avoiding additional complexity.
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
Enables seamless steering wheel position synchronization with the steering gear, reducing the required rotation to a fraction of a full turn, and allows for flexible button placement and design, minimizing modifications to existing steering wheel architectures.
Implementation Method 1
a force-feedback actuator for artificially generating a hand torque, which, during manual steering by the driver, provides feedback from the steering gear to the steering wheel
Implementation Method 2
if wireless energy and signal transmission is established between the stationary vehicle structure (such as a steering column module) and the rotating driver interface (steering wheel)
Data Source
Figure 1~2
Figure 3a~3b
Figure 3c~4
AI summary
The invention relates to a method for steering gear-steering wheel position synchronization in a steer-by-wire vehicle (2). The vehicle comprises a steering wheel (9) mechanically decoupled from a steering gear (6), which can be rotated about its axis any number of times, and a force-feedback actuator (M) designed to generate a hand torque which provides feedback from the steering gear (6) to the steering wheel (9).The procedure comprises the following steps: receiving a request for steering gear-steering wheel position synchronization after an automated driving or parking regime in which the steering wheel (9) was not adjusted to the steering gear (6); providing current values of a steering angle position of the steering wheel (9) corresponding to the steering gear (6) on the one hand and an actual steering angle position of the steering wheel (9) on the other hand and determining a difference between these values; determining a steering wheel rotation to be performed for steering gear-steering wheel position synchronization from the determined difference, taking into account a predetermined steering angle period that corresponds to a full steering wheel rotation or less; and performing the steering wheel rotation thus determined.