Steer-by-Wire Steering Synchronization by Deviation Range
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Solution Overview
Problem
In steer-by-wire steering systems, the rotational position of the steering wheel can deviate from the turning wheels' position when external forces are applied with the power off, leading to a disrupted correspondence relationship that existing correction methods do not adequately address.
Innovation Solution
A steering control device that executes synchronization control through a control unit to correct the positional relationship between the steering wheel and turning wheels using turning-side and steering-side synchronization controls, tailored to different deviation ranges to minimize driver discomfort and ensure quick alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single correction process is used to align the steering wheel and turning wheels, then the positional relationship can be corrected, but the driver may experience discomfort due to unnecessary steering wheel rotation when the deviation is small
Solution Approach 1:
The system changes the control parameter (deviation amount threshold) to determine whether to execute the correction process. When the deviation amount exceeds a predetermined threshold, the correction process is activated; otherwise, it is suppressed. This parameter-based decision-making resolves the contradiction by adapting the correction behavior to the actual deviation magnitude, ensuring alignment precision when needed while avoiding unnecessary corrections that would cause driver discomfort.
2Manufacturing precision
If the correction process is executed frequently to maintain precise positional relationship, then alignment accuracy is improved, but the system complexity and processing load increase
Solution Approach 1:
The system performs a preliminary check of the deviation amount before executing the correction process. By evaluating whether the deviation exceeds the predetermined threshold in advance, the system avoids unnecessary correction operations. This preliminary action simplifies the control logic and reduces processing load while maintaining alignment accuracy, as corrections are only performed when actually needed.
3Speed
If the steering actuator is used for correction, then the rotational position can be adjusted quickly, but the steering reaction force may cause discomfort to the driver
Solution Approach 1:
The system uses the turning actuator as an intermediary to perform the correction process indirectly. Instead of directly rotating the steering wheel with the steering actuator (which would apply reaction force to the driver), the turning actuator adjusts the turning wheels position to match the steering wheel position. This intermediary approach achieves the desired alignment while avoiding direct mechanical interaction with the driver, thus maintaining both correction speed and driver comfort.
Data Source
Figure 1
Figure 2~3
Figure 4~5(b)
AI summary
A steering control device (1) controls, as a target, a steering device (2) including a steering actuator (12) and a turning actuator (31) that has a structure with a power transmission path cut off from the steering actuator (12). The steering control device (1) includes a control unit. The control unit is configured to execute: turning-side synchronization control when the absolute value of a deviation amount is a value within a first range; steering-side synchronization control when the absolute value of the deviation mount is a value within a second range that is a larger value than a value within the first range; and at least one of the turning-side synchronization control and the steering-side synchronization control when the absolute value of the deviation amount is a value within a third range that is a value between a value within the first range and a value within the second range.