Vehicle Suspension Damping Control With Adaptive Filter Cutoff
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Solution Overview
Problem
Existing vehicle suspension systems struggle with inefficient damping control, particularly in handling non-linear suspension dynamics and signal drift in acceleration and velocity signals, leading to suboptimal ride comfort and responsiveness.
Innovation Solution
Implementing a non-linear gain control mechanism based on body velocities and dynamically tuning a high-pass filter cutoff frequency to filter acceleration signals, along with load-compensated suspension damping to adapt to varying road conditions and vehicle loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a fixed gain value is applied to damping force across all velocity ranges, then the control system is simple, but it cannot account for non-linear suspension dynamics and provides suboptimal ride comfort
Solution Approach 1:
The patent applies a non-linear gain schedule where the gain value varies dynamically with body velocity. At low velocities, a higher gain is applied for better comfort, while at high velocities, a lower gain prevents excessive damping. This dynamic adjustment resolves the contradiction by adapting the control parameter (gain) to the operating conditions (velocity) rather than using a fixed value.
Solution Approach 2:
The patent changes the damping control parameter (gain value) based on the velocity signal magnitude. By modifying the gain parameter as a function of velocity, the system achieves both simplicity (through a predefined gain schedule) and reliability (through velocity-adaptive damping). This parameter change approach allows the system to handle non-linear suspension dynamics effectively.
2Productivity
If acceleration signal is integrated to obtain velocity signal without filtering, then the velocity signal is readily available, but signal drift accumulates leading to inaccurate velocity values
Solution Approach 1:
The patent applies a high-pass filter to the acceleration signal before integration to prevent drift accumulation. By removing low-frequency components (including DC offsets) in advance, the integration process produces accurate velocity signals without drift accumulation. This preliminary filtering action resolves the contradiction by preparing the signal in advance to avoid the drift problem during integration.
Solution Approach 2:
The high-pass filter acts as an intermediary between the acceleration signal and the integration process. It processes the acceleration signal to remove drift-causing components before the signal is integrated to obtain velocity. This intermediary filtering step maintains both productivity (velocity availability) and measurement precision (velocity accuracy).
3Device complexity
If a high-pass filter with fixed cutoff frequency is used to filter acceleration signals, then the filter design is simple, but it cannot adapt to varying road conditions and vehicle loads
Solution Approach 1:
The patent implements a dynamic cutoff frequency for the high-pass filter that varies with vehicle velocity. At low velocities, a lower cutoff frequency is used to preserve relevant signal components, while at high velocities, a higher cutoff frequency removes high-frequency noise and vibrations. This dynamic adjustment resolves the contradiction by adapting the filter characteristic to the operating conditions rather than using a fixed cutoff frequency.
Solution Approach 2:
The patent changes the filter parameter (cutoff frequency) based on the velocity signal. By making the cutoff frequency a function of velocity, the system achieves both simplicity (through a velocity-based selection rule) and adaptability (through automatic adjustment to road conditions and vehicle loads). This parameter change approach allows the filter to optimize performance across different operating scenarios.
4Stability of the object's composition
If damping force is applied without velocity-based gain adjustment, then the damping system responds uniformly, but it provides poor responsiveness to varying driving conditions
Solution Approach 1:
The patent applies velocity-based dynamic gain adjustment to the damping force. The gain value changes with velocity to optimize damping characteristics: higher gain at low velocities for comfort, lower gain at high velocities for stability. This dynamic adjustment resolves the contradiction by making the damping system responsive to varying driving conditions while maintaining consistent and reliable damping performance across the operating range.
Data Source
AI summary
A vehicle includes a suspension system having a damping system that includes a plurality of dampers and a plurality of damper valves. The vehicle further includes one or more processors configured to determine energy content of an acceleration signal indicative of acceleration of the vehicle. The one or more processors are further configured to dynamically tune a cutoff frequency of a high-pass filter based on the energy content of the acceleration signal. The one or more processors are configured to filter, via the high-pass filter, a velocity signal derived from the acceleration signal to output a filtered velocity signal. The one or more processors are configured to control operation of the damping system based on the filtered velocity signal.