Steering System Resonance-Band Limiting Control
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Solution Overview
Problem
Existing steering systems do not adequately address resonance between the steering device and vehicle motion, leading to unexpected vehicle behavior and instability.
Innovation Solution
A steering system with a controller that calculates a target steering angle and frequency, executing normal control when outside a resonance frequency band and limiting control when within, maintaining the actual steering angle constant, decreasing its value, or shifting it outside the resonance band to prevent resonance-induced vehicle behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If normal steering control is executed without frequency detection, then the steering response is fast and responsive, but resonance occurs between the steering device and vehicle motion causing unexpected vehicle behavior
Solution Approach 1:
The controller performs preliminary detection of the steering variable frequency before executing steering control. By calculating the frequency in advance and comparing it with the resonance frequency band, the system prepares appropriate control parameters to avoid resonance, thereby preventing unstable vehicle behavior before it occurs while maintaining fast steering response.
Solution Approach 2:
The system continuously detects the steering variable frequency and uses this feedback to adjust the steering control in real-time. When the detected frequency approaches the resonance frequency band, the controller modifies the control parameters to avoid resonance, creating a closed-loop control system that maintains both responsiveness and stability.
2Stability of the object's composition
If the steering control is adjusted to avoid resonance frequency band, then vehicle behavior stability is improved, but the steering control complexity increases due to frequency detection and conditional control logic
Solution Approach 1:
The system changes the control parameter from a fixed steering angle command to a frequency-adaptive control parameter. By detecting the steering variable frequency and comparing it with the resonance frequency band, the controller dynamically adjusts control parameters to avoid resonance, achieving stability without requiring complex mechanical modifications.
Solution Approach 2:
Instead of using complex mechanical damping mechanisms or physical modifications to prevent resonance, the system substitutes a computational approach by detecting steering variable frequency and using software-based conditional control logic to avoid resonance frequency band, thereby reducing mechanical complexity while improving stability.
3Stability of the object's composition
If the actual steering angle is maintained constant or decreased in limiting control, then resonance is suppressed and vehicle behavior is stabilized, but the steering precision and accuracy are reduced
Solution Approach 1:
The system applies limiting control only partially by restricting the steering angle to a predetermined value or decreasing its absolute value when resonance is detected, rather than completely blocking the steering input. This partial action is sufficient to suppress resonance and stabilize vehicle behavior while preserving some steering authority and precision.
Solution Approach 2:
The control system dynamically switches between normal control mode and limiting control mode based on the detected steering variable frequency. When the frequency is outside the resonance band, full steering precision is maintained; when inside the resonance band, limiting control is applied to stabilize vehicle behavior, creating a dynamic adaptation that balances precision and stability.
Data Source
AI summary
A steering system includes a controller configured to: execute a normal control to control a front-wheel steering device or a rear-wheel steering device based on a target steering angle when a steering-related frequency is determined to fall outside a resonance frequency band; and execute a limiting control when the steering-related frequency is determined to fall within the resonance frequency band. In the limiting control, the controller controls the front-wheel or rear-wheel steering device such that (i) an actual steering angle is constant at a predetermined value, (ii) an absolute value of the actual steering angle gradually decreases from a specific value, (iii) a frequency of the actual steering angle falls outside the resonance frequency band, or (iv) the absolute value of the actual steering angle is less than an absolute value of the latest value of a target extreme value that is an extreme value of the target steering angle.