Steering Wheel Speed Control for Smooth Alignment
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Solution Overview
Problem
In steer-by-wire steering systems, the automatic correction of the steering wheel's rotational position upon vehicle power-on can cause discomfort for the driver due to sudden rotation or stopping, as the steering wheel is not restricted by the turning mechanism when external forces are applied while the vehicle is off, leading to misalignment with the turning wheels.
Innovation Solution
A steering system with a control unit that gradually adjusts the rotation speed of the steering wheel to zero when stopping and increases it smoothly when starting, along with a stopper mechanism to restrict rotation and calculate a neutral position, ensuring a smooth and synchronized alignment with the turning wheels, thereby reducing driver discomfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the steering wheel is automatically rotated to correct the positional relationship between the steering wheel and turning wheels, then the alignment accuracy is improved, but the driver experiences discomfort due to sudden rotation and stopping
Solution Approach 1:
The control unit changes the rotation speed parameter of the steering wheel from a constant value to a variable value that decreases gradually over time. This parameter change ensures the steering wheel reaches the target position accurately while the rotation speed smoothly approaches zero, eliminating sudden stopping that causes driver discomfort.
Solution Approach 2:
The system transitions from a static correction process to a dynamic one by continuously adjusting the rotation speed during the correction process. The control unit dynamically modifies the motor output to achieve a smooth deceleration profile, making the correction process adaptive and comfortable for the driver.
2Loss of time
If the steering wheel rotation is stopped suddenly to complete the correction process quickly, then the correction time is reduced, but the driver experiences discomfort due to abrupt stopping
Solution Approach 1:
The control unit modifies the rotation speed parameter by implementing a gradual decrease function. Instead of maintaining constant speed until abrupt stopping, the system continuously reduces the speed parameter as the steering wheel approaches the target position, achieving both reasonable correction time and driver comfort.
3Stability of the object's composition
If the steering wheel is restricted by the turning mechanism, then the positional relationship is maintained, but the steer-by-wire system loses its advantage of decoupling steering input from turning output
Solution Approach 1:
The system performs preliminary correction of the steering wheel position when the vehicle is powered on or when misalignment is detected. By proactively adjusting the steering wheel to the correct position before normal operation begins, the system maintains positional relationship stability without requiring continuous mechanical restriction during driving.
Solution Approach 2:
The control unit continuously monitors the rotational position of the steering wheel and compares it with the expected position based on turning wheel position. This feedback mechanism allows the system to maintain accurate positional relationships while preserving steer-by-wire flexibility, correcting deviations through controlled motor action rather than mechanical restriction.
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
The gradual speed adjustments and stopper mechanism enhance the smoothness of steering wheel rotation and alignment, minimizing driver discomfort during automatic corrections and maintaining the predetermined steering angle ratio, thus improving the overall steering experience.
Implementation Method 1
a motor configured to generate a torque that is applied to the steering shaft
Data Source
AI summary
A steering system includes a steering shaft that rotates along with an operation of a steering wheel; a motor configured to generate a torque that is applied to the steering shaft; and a control unit configured to control the motor. The control unit is configured to control the motor such that a rotation speed of the steering wheel decreases gradually to zero when automatic rotation of the steering wheel is stopped, in a case where the steering wheel is automatically rotated as an adjustment process of adjusting a rotational position of the steering wheel.