Steering Control Apparatus Adaptive Return Speed
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Solution Overview
Problem
Conventional steering control systems experience sudden increases in steering wheel return speed during return control, causing driver discomfort due to inadequate management of return control output.
Innovation Solution
A steering control apparatus that includes a return control unit with a target steering speed calculating unit, a return control amount calculating unit, and a returning state determining unit, which gradually increases the target steering speed when the steering wheel is returning to neutral, preventing sudden changes in return speed by determining the returning state based on steering wheel position and speed-related information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the return control amount is calculated based on the deviation between target steering speed and steering speed, then the steering wheel returns to neutral position, but the returning speed suddenly increases causing driver discomfort
Solution Approach 1:
The patent applies dynamics by making the target steering speed adaptive rather than fixed. The control system dynamically adjusts the target steering speed based on the current steering speed and acceleration, allowing the return control to respond smoothly to changing conditions rather than enforcing a rigid speed profile that causes sudden changes and discomfort.
Solution Approach 2:
The patent changes the parameter of target steering speed from a constant or simply proportional value to one that is calculated considering both steering speed and steering acceleration. This parameter change allows the system to account for the dynamic state of the steering wheel, preventing sudden speed changes by adjusting the target based on current motion parameters.
2Stability of the object's composition
If the gain is reduced to suppress return control output during steady steering, then steering stability is improved, but the return control effectiveness is reduced
Solution Approach 1:
The patent applies local quality by making the return control gain spatially and operationally variable. Instead of using a uniform gain across all steering conditions, the system calculates different effective gains based on the operating state (steady steering versus returning). This allows high gain effectiveness during returning while maintaining low gain during steady steering, resolving the contradiction between stability and effectiveness.
Solution Approach 2:
The system dynamically adjusts the effective return control gain based on the detected steering state. When the steering wheel is in steady steering, the gain is reduced for stability; when returning to neutral, the gain is increased for effectiveness. This dynamic adaptation resolves the contradiction by allowing the system to optimize for different operational requirements at different times.
Data Source
AI summary
In a steering control apparatus, a basic assistance torque calculating unit calculates a basic assistance torque. A return control unit calculates a return control amount to assist in returning a steering wheel to a neutral position, as a correction torque to be added to the basic assistance torque. In the return control unit, a target steering speed calculating unit calculates a target steering speed being that is a target value for a steering speed. A return control amount calculating unit calculates the return control amount such that the steering speed follows the target steering speed. A returning state determining unit determines whether the steering wheel is turning or returning. The target steering speed calculating unit gradually increases an absolute value of the target steering speed from an absolute value of the steering speed when the steering wheel is returning.