Variable Damper Suspension Control for Unsprung Vibration Damping
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional skyhook control methods experience low convergent property and ride comfort issues due to unsprung resonance vibrations, leading to a 'tramp sensation' and 'feeling of hardness' caused by insufficient damping of unsprung mass vibrations.
Innovation Solution
A suspension control method that temporarily holds the damping coefficient, allowing damping force application to the unsprung mass independent of current stroke speed, and switches between skyhook control using Karnopp's law and non-application based on the relationship between sprung mass speed and stroke speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional skyhook control using Karnopp's law is applied, then the control system operates smoothly under normal conditions, but unsprung resonance vibrations are not sufficiently damped causing tramp sensation and feeling of hardness
Solution Approach 1:
The control method dynamically switches between two control modes (first control mode and second control mode) based on real-time detection of stroke speed and sprung mass speed. When stroke speed is high, the first control mode is used; when stroke speed is low, the second control mode is used. This dynamic adaptation allows the system to optimize damping performance across different operating conditions, effectively suppressing unsprung resonance vibrations while maintaining smooth operation under normal conditions.
Solution Approach 2:
The invention changes the control parameters by using different control strategies based on the relationship between stroke speed and sprung mass speed. In the first control mode, the damping force is controlled based on stroke speed; in the second control mode, the damping force is controlled based on sprung mass speed. This parameter change enables the system to apply appropriate damping forces to suppress unsprung resonance vibrations and improve ride comfort.
2Reliability
If gain correction is applied to improve convergent property, then vehicle attitude control improves, but damping force is not properly applied to target damping force when signs of speeds do not match
Solution Approach 1:
The control method dynamically switches between two control modes (first control mode and second control mode) based on real-time detection of stroke speed and sprung mass speed. When stroke speed is high, the first control mode is used; when stroke speed is low, the second control mode is used. This dynamic adaptation allows the system to optimize damping performance across different operating conditions, effectively suppressing unsprung resonance vibrations while maintaining smooth operation under normal conditions.
Solution Approach 2:
The control method uses feedback from speed sensors to detect the relationship between stroke speed and sprung mass speed in real-time. Based on this feedback, the control unit determines which control mode to apply, ensuring that the appropriate damping force is applied to achieve the target damping force accurately under different operating conditions.
3Ease of operation
If damping force is reduced when stroke speed is low, then Karnopp's law is followed, but unsprung vibrations are not damped sufficiently causing resonance
Solution Approach 1:
The control method dynamically switches between two control modes (first control mode and second control mode) based on real-time detection of stroke speed and sprung mass speed. When stroke speed is high, the first control mode is used; when stroke speed is low, the second control mode is used. This dynamic adaptation allows the system to optimize damping performance across different operating conditions, effectively suppressing unsprung resonance vibrations while maintaining smooth operation under normal conditions.
Solution Approach 2:
The invention changes the control parameters by using different control strategies based on the relationship between stroke speed and sprung mass speed. In the first control mode, the damping force is controlled based on stroke speed; in the second control mode, the damping force is controlled based on sprung mass speed. This parameter change enables the system to apply appropriate damping forces to suppress unsprung resonance vibrations and improve ride comfort.
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 approach effectively reduces the 'tramp sensation' and 'feeling of hardness' by ensuring damping force application to unsprung vibrations, improving ride comfort and convergent properties of vehicle attitude control.
Implementation Method 1
a variable damping force damper provided in a suspension mechanism is a known technology for controlling vehicle vibration
Data Source
Figure 1
Figure 2
Figure 3
AI summary
To eliminate unsprung tramp sensations and feelings of hardness when the stroke speed decreases in a conventional skyhook control. The present invention comprises a control device configured to apply, to a variable damping force damper, a target control force determined based on a damping coefficient of the variable damping force damper in a suspension mechanism. The control device includes a state estimation unit for calculating the sprung mass speed of the sprung mass based on a value detected by several of a plurality of sensors, an application control unit for calculating and outputting a damping coefficient of the variable damping force damper based on the calculated sprung mass speed, and a target control amount management unit for determining the target control force based on the damping coefficient output by the application control unit. In addition, in the case of a first condition, the control device determines a target control force based on a damping coefficient held in advance.