Steering System Conditional Wheel Position Correction
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Solution Overview
Problem
In steer-by-wire steering systems, the automatic correction of the steering wheel's positional relationship with the turning wheels when power is restored can cause discomfort and stress for the driver, as the steering wheel may rotate unexpectedly, preventing the vehicle from being started until the correction process is complete.
Innovation Solution
A steering system with a control unit that assesses the displacement between the steering wheel and turning wheels upon power restoration and only performs correction processes when the displacement exceeds predetermined thresholds, allowing for controlled synchronization to prevent unnecessary rotation and minimize driver discomfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the control unit performs automatic correction of the steering wheel's rotational position when power is turned on, then the positional relationship between the steering wheel and turning wheels is reliably improved, but the driver experiences discomfort and stress due to unexpected steering wheel rotation
Solution Approach 1:
The control unit changes the operational parameter from automatic correction to conditional correction based on displacement magnitude. When the displacement between steering wheel and turning wheels exceeds a predetermined threshold, correction is performed; when it remains within the threshold, correction is omitted. This parameter-based decision approach resolves the contradiction by adapting the correction behavior to the actual displacement condition, ensuring accuracy when needed while avoiding unnecessary corrections that cause driver discomfort.
2Manufacturing precision
If the control unit performs correction process to synchronize steering wheel and turning wheels, then the positional accuracy is improved, but the vehicle startup time is delayed until correction completes
Solution Approach 1:
The control unit applies partial correction action by performing synchronization only when displacement exceeds the predetermined threshold. When the displacement is already within acceptable limits, no correction is performed, allowing the vehicle to start immediately. This partial action approach resolves the contradiction by eliminating unnecessary correction operations that would delay startup, while still ensuring positional accuracy when the displacement is significant.
3Adaptability or versatility
If the steering wheel is allowed to rotate freely when power is off, then the steering system flexibility is maintained, but the positional relationship between steering wheel and turning wheels becomes incorrect
Solution Approach 1:
The control unit implements a feedback mechanism that detects the displacement between the steering wheel position and turning wheel position after power is turned on. Based on this feedback information, the control unit determines whether correction is necessary and executes the correction process accordingly. This feedback approach resolves the contradiction by allowing the steering wheel to rotate freely during operation while automatically restoring positional accuracy when displacement exceeds the threshold, thus maintaining both flexibility and 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 reduces driver discomfort and stress by ensuring the steering wheel does not automatically rotate when power is restored, allowing for smoother vehicle startup and reducing the time the driver must wait for the correction process to finish.
Implementation Method 1
a reaction motor configured to generate a steering reaction force that is a torque applied to the steering shaft in a direction opposite to a steering direction
Data Source
Figure 1
Figure 2~3(b)
Figure 4(a)~5(c)
AI summary
A steering system includes a steering shaft (21); a reaction motor (22); and a control unit configured to control the reaction motor (22). The control unit has a function of performing a correction process of rotating the steering wheel (11) using the reaction motor (22) such that a displacement in a rotational position of the steering wheel (11) with respect to a correct rotational position corresponding to a turning position of the turning wheels decreases when a power supply of the vehicle is turned on and the rotational position of the steering wheel (11) is different from the correct rotational position. The control unit is configured to perform the correction process when the displacement is equal to or greater than a predetermined permissible value and not to perform the correction process when the displacement is less than the permissible value.