Vehicle Suspension Preview Control With Adaptive Feedback Gain
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Solution Overview
Problem
Existing suspension control systems face challenges in appropriately adjusting feedback gain due to inaccuracies in road surface displacement-associated values, leading to excessive vibrations in both low and medium-to-high frequency bands, especially when preview damping control is ineffective.
Innovation Solution
A suspension control system that includes an actuator and a control device for adjusting suspension stroke, which executes feedforward and feedback control based on road surface displacement-associated values and vehicle states, adjusting feedback gain based on the reliability of preview control and the ratio of frequency bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If feedback gain is increased to suppress low frequency vibrations, then low frequency vibrations are reduced, but medium-to-high frequency vibrations are exacerbated
Solution Approach 1:
The feedback gain is made dynamically adjustable rather than fixed. The control device changes the feedback gain based on the reliability of preview control and the frequency characteristics of road surface inputs, allowing optimal suppression of vibrations across different frequency bands under varying operating conditions
Solution Approach 2:
The feedback gain parameter is changed based on the ratio between low frequency and medium-to-high frequency components of road surface displacement. When medium-to-high frequency components dominate, the feedback gain is reduced to avoid exacerbating those vibrations, while maintaining adequate gain for low frequency suppression when appropriate
2Object-affected harmful factors
If feedback gain is reduced to suppress medium-to-high frequency vibrations, then medium-to-high frequency vibrations are reduced, but low frequency vibrations become excessive
Solution Approach 1:
The feedback gain is dynamically adjusted based on real-time assessment of preview control reliability and frequency content. When preview control is reliable and medium-to-high frequency inputs are present, gain is reduced; when preview control reliability is low, gain is increased to maintain low frequency suppression
Solution Approach 2:
The feedback gain parameter is modified according to the ratio of low frequency to medium-to-high frequency components in road surface displacement. This allows the system to adaptively change the damping characteristics to match the actual road input spectrum
3Object-affected harmful factors
If preview damping control is used to reduce input to sprung structure, then low frequency vibrations are suppressed, but medium-to-high frequency vibrations may be exacerbated due to feedback control
Solution Approach 1:
The system uses feedback control with dynamically adjusted gain to complement preview damping control. The feedback loop monitors the actual vehicle response and adjusts the feedback gain based on the reliability of preview information and the frequency characteristics of road inputs, creating a coordinated control strategy that addresses both frequency bands
Solution Approach 2:
The feedback gain parameter is changed based on the ratio between low frequency and medium-to-high frequency components of road surface displacement. When medium-to-high frequency components are significant, the feedback gain is reduced to prevent exacerbation, while maintaining the benefits of preview control for low frequency suppression
Data Source
AI summary
A first acquisition unit acquires a road surface displacement-associated value related to up-down direction displacement of a road surface forward of a vehicle. A second acquisition unit acquires a state related to up-down direction displacement of a sprung structure or an unsprung structure of the vehicle. A deriving unit derives, in time series data of the road surface displacement-associated value or the state that is acquired, a ratio between a magnitude of a component of a first frequency band and a magnitude of a component of a second frequency band. A control unit executes feedforward control based on the road surface displacement-associated value that is acquired, and also executes feedback control based on the state that is acquired. A setting unit sets, when the derived ratio is no less than a threshold value, and also the feedforward control is not being appropriately executed, the feedback gain to be great.