Steering System Control Unit Limiting Target Angle Change Range
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In steer-by-wire steering systems, the automatic rotation of the steering wheel can be hindered by a driver's grip or objects, leading to a difference between the target steering angle and the actual steering angle, causing discomfort due to sudden rotation when the hindrance is released.
Innovation Solution
A steering system with a control unit that performs steering angle feedback control and sets a limit value for the change range of the target steering angle during automatic rotation hindrance, limiting the difference between the target and actual steering angles to prevent sudden changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the control unit performs automatic rotation adjustment of the steering wheel after power-on, then the positional relationship between the steering wheel and turning wheels is corrected, but the steering wheel may rotate suddenly when hindered by a driver's grip or object, causing driver discomfort
Solution Approach 1:
The control unit dynamically adjusts the target steering angle based on the current steering angle and a predetermined change amount. Instead of directly commanding the final target angle, the system incrementally updates the target steering angle in controlled steps, allowing the steering wheel to rotate smoothly even when initially hindered by a driver's grip or object.
Solution Approach 2:
The control unit preliminarily determines a corrected target steering angle based on the stored off-state steering angle and the current on-state steering angle before executing the rotation. This preliminary calculation establishes a safe target that accounts for potential hindrances, preventing sudden movements while ensuring the positional relationship is ultimately corrected.
2Productivity
If the steering wheel is allowed to rotate freely to reach the target steering angle, then the adjustment process is completed quickly, but the sudden rotation may occur when the hindrance is released, causing driver discomfort
Solution Approach 1:
The system dynamically controls the rotation speed and target angle updates. By adjusting the target steering angle in incremental steps rather than commanding the full rotation at once, the system maintains a balance between completion speed and safety, preventing sudden movements while still achieving the adjustment efficiently.
Solution Approach 2:
The control unit implements a cushioning mechanism by limiting the change amount of the target steering angle. This predetermined limit acts as a buffer that prevents the steering wheel from rotating too quickly or too far in a single step, cushioning against potential sudden movements that would cause driver discomfort.
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 configuration reduces driver discomfort by preventing sudden steering wheel movements when the hindrance is resolved, maintaining a stable rotational position during adjustment processes.
Implementation Method 1
a motor configured to generate a torque that is applied to the steering shaft
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A steering system includes a steering shaft (21); a motor (22) configured to generate a torque applied to the steering shaft (21); and a control unit configured to control the motor (22). The control unit has a function of performing steering angle feedback control for causing a steering angle that is a rotation angle of a steering wheel (11) to reach a target steering angle that is set based on a point of view of adjusting a rotational position of the steering wheel (11), as an adjustment process of adjusting the rotational position of the steering wheel (11). The control unit is configured to set a limit value for limiting a change range of the target steering angle with respect to the steering angle at each moment in a period in which automatic rotation of the steering wheel (11) is hindered in a case where the automatic rotation is hindered while the adjustment process is being performed.