Variable-Ratio Steering Wheel Control for Manual Takeover
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Solution Overview
Problem
During automatic driving mode transitions to manual driving mode, the discrepancy between the driver's perceived steering angle and the actual steering angle can lead to confusion, as the steering wheel can be rotated 360 degrees, causing a mismatch between the driver's understanding of the vehicle's direction and its actual direction.
Innovation Solution
A steering device with a rotatable steering wheel and a control mechanism that adjusts the ratio of steering angle to steered angle, limiting the steering angle in automatic mode to less than 180 degrees and gradually changing this ratio when switching modes to prevent abrupt changes, ensuring the driver's perception aligns with the actual steering angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the steering wheel is allowed to rotate 360 degrees or more during automatic driving mode, then the steering mechanism achieves high adaptability for various driving scenarios, but the driver's perceived steering angle diverges from the actual steering angle causing confusion and safety issues
Solution Approach 1:
The steering device dynamically adjusts the steering ratio based on driving mode. During automatic driving mode, the control device sets the steering ratio to a first value that limits the steering angle to less than 180 degrees, preventing confusion. When switching to manual driving mode, the ratio is changed to a second value that allows the steering wheel to rotate more than 180 degrees, ensuring the driver can perform emergency maneuvers while maintaining accurate perception of steering angle.
Solution Approach 2:
The invention changes the steering ratio parameter according to driving mode. The control device switches between a first steering ratio (during automatic driving) and a second steering ratio (during manual driving), where the first ratio limits the steering angle to maintain driver awareness, and the second ratio enables full steering wheel rotation for emergency situations.
2Speed
If the steering ratio is changed abruptly when switching from automatic driving mode to manual driving mode, then the system responds quickly to driver input, but the sudden change in steering angle causes driver confusion and loss of vehicle control
Solution Approach 1:
The control device prepares for mode switching by gradually changing the steering ratio before the actual mode transition completes. When switching from automatic to manual driving mode, the control device gradually increases the steering ratio, allowing the steering wheel angle to adjust progressively rather than abruptly, preventing driver confusion while maintaining quick overall response.
3Ease of operation
If the steering ratio is set to allow full steering wheel rotation during automatic driving mode, then the steering mechanism maintains high maneuverability, but the driver may misunderstand the vehicle's actual traveling direction
Solution Approach 1:
The steering device dynamically adjusts the steering ratio based on driving mode. During automatic driving mode, the control device sets the steering ratio to a first value that limits the steering angle to less than 180 degrees, preventing confusion. When switching to manual driving mode, the ratio is changed to a second value that allows the steering wheel to rotate more than 180 degrees, ensuring the driver can perform emergency maneuvers while maintaining accurate perception of steering angle.
Data Source
AI summary
A steering device includes: a steering wheel which is rotatable over an angle range exceeding 180 degrees in each of leftward and rightward directions from a neutral position; a steering mechanism that steers a wheel according to a steering angle of the steering wheel, with a ratio of the steering angle to a steered angle being changeable; and a control device that controls the ratio of the steering mechanism. The control device sets the ratio to a first value during travel of a vehicle in the manual driving mode and sets the ratio to a second value smaller than the first value during travel of the vehicle in the automatic driving mode, wherein the second value is set such that the steering angle corresponding to a maximum steered angle of the wheel specified by the steering mechanism is less than 180 degrees.