Steering Control Device Two-Step Synchronization Relay Angle
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Solution Overview
Problem
In steer-by-wire steering systems, drivers may feel uneasy during synchronization operations, especially when the ignition is turned on after the steering wheel has been adjusted in the off state, due to the opposite rotation direction required to align the steering and turning angles, leading to uncertainty about reaching the correct correspondence.
Innovation Solution
A steering control device performs a two-step synchronization operation by calculating a target synchronization angle and a target relay angle, ensuring the steering wheel rotates first towards one side and then the other, maintaining a consistent operation manner regardless of the initial angle difference, and setting minimum or intermediate rotation amounts to optimize visibility and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the steering wheel is rotated directly to align the steering angle with the turning angle in a single step, then the synchronization operation is completed quickly, but the rotation direction may be opposite to the driver's habitual direction causing unease
Solution Approach 1:
The synchronization operation is divided into two distinct steps: first rotating the steering wheel in a standard direction to a relay angle, then rotating in the opposite direction to the target angle. This segmentation allows the driver to perceive a predictable initial rotation direction while still achieving the required alignment, reducing unease caused by unexpected opposite-direction rotation.
Solution Approach 2:
A relay angle is introduced as an intermediate target position between the current steering angle and the final target angle. This relay angle serves as a mediator that breaks the direct opposite-direction rotation into two manageable steps, with the first step always rotating in a predictable direction toward the relay angle before the second step completes the alignment.
2Measurement precision
If the steering wheel rotates a large angle to correct misalignment, then the synchronization accuracy is improved, but the operation time increases and driver unease worsens
Solution Approach 1:
The large correction angle is segmented into two smaller rotation steps: the first step rotates to an intermediate relay angle, and the second step completes the alignment to the target angle. This segmentation reduces the perceived rotation magnitude in each step while maintaining the total alignment accuracy, and allows parallel motor control to execute both steps efficiently.
Data Source
AI summary
A steering control device includes control circuitry configured to perform synchronization control. The synchronization control includes a target synchronization angle calculating process of calculating a target synchronization angle that is a steering-side rotation angle satisfying a predetermined correspondence relationship with respect to a turning-side rotation angle; a target relay angle calculating process of calculating a target relay angle that is located closer to a first side in a circumferential direction than a first-side angle is, the first-side angle being one of the steering-side rotation angle and the target synchronization angle and being located closer to the first side than another of the steering-side rotation angle and the target synchronization angle is; and a motor driving process of operating a steering-side motor such that the steering-side rotation angle reaches the target synchronization angle after operating the steering-side motor such that the steering-side rotation angle reaches the target relay angle.