Vehicle Suspension Stroke Estimation via Shock Absorber Pressure
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Solution Overview
Problem
Existing methods for estimating the stroke of a vehicle's suspension, such as using linear potentiometers, are fragile, costly, and not easily derivable from force measurements, leading to inaccurate and impractical solutions.
Innovation Solution
A method that associates the pressure inside a shock absorber with the suspension stroke using a pressure sensor, employing a black box model and dynamic filtering to reduce estimation errors, and incorporates a recalibration system based on vehicle speed and braking state to adapt to changing conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a linear potentiometer is used to measure suspension stroke, then measurement precision is improved, but device complexity and cost increase, and reliability decreases due to fragility
Solution Approach 1:
The patent replaces the mechanical linear potentiometer sensor with a pressure sensor that measures hydraulic pressure in the shock absorber. This substitution uses pressure measurement (fluid mechanics) instead of mechanical displacement measurement, eliminating the fragility of moving parts while maintaining measurement capability through the pressure-stroke relationship defined by the suspension's mechanical characteristics.
2Measurement precision
If a linear potentiometer is used to measure suspension stroke, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces the complex mechanical potentiometer assembly with a simpler pressure sensor integrated into the hydraulic system. The measurement complexity is shifted from mechanical displacement sensing to pressure sensing, which is inherently simpler and can be implemented using standard automotive pressure sensors already present in the vehicle's braking or suspension systems.
Solution Approach 2:
The patent leverages the existing hydraulic pressure system that serves multiple functions (suspension control, shock absorption) to also provide stroke measurement. The same hydraulic fluid and pressure chamber used for suspension operation are utilized for sensing, eliminating the need for a separate dedicated measurement system.
3Device complexity
If force measurement is used to estimate suspension stroke, then device complexity is reduced, but measurement precision deteriorates due to difficulty in separating force components
Solution Approach 1:
The patent changes the measurement parameter from force (which requires decomposition into multiple components) to pressure (which provides direct information about the spring force). The pressure-stroke relationship is determined through system identification, creating a direct mapping that avoids the complexity of force component separation while maintaining measurement precision.
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 provides a strong, cost-effective, and highly accurate estimation of the suspension stroke with negligible errors, capable of dynamic adaptation to vehicle work conditions, using existing vehicle control units and sensors.
Implementation Method 1
a pressure sensor (12) to be mounted on the shock absorber
Data Source
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AI summary
The present invention refers to a method for estimating the suspension stroke of a vehicle comprising the steps consisting of: a) determining a variability law (10) that associates the stroke of the suspension with the pressure inside a shock absorber of the same, based on experimental data; b) estimating the suspension stroke value related to a measured pressure value, based on the variability law (10) identified in step (a); c) detecting/obtaining the longitudinal vehicle dynamics; d) recalibrating (30) the variability law (10) identified in step a), based on the longitudinal vehicle dynamics detected/obtained in step c). The present invention also refers to an apparatus for implementing the estimation method of the suspension stroke of a vehicle according to the invention.