Vehicle Body Vibration Estimation Using Wheel Speed Correlation
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Solution Overview
Problem
Conventional vehicle body vibration estimating technologies face challenges in accurately estimating vibrations due to external disturbances, such as uneven road surfaces, as they rely on varying parameters like spring constant and vehicle mass, which degrade over time and are influenced by the number of occupants, leading to incorrect torque calculations and reduced precision.
Innovation Solution
A vehicle body vibration estimating device that uses wheel speed information and correlation relationships between back-and-forth and up-and-down displacements to estimate vibrations, eliminating the need for torque and force calculations based on varying parameters, thereby improving precision and excluding external disturbance influences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If vehicle body vibration is estimated using a vehicle body movement model from driving braking force, then vibration estimation can be performed, but external disturbances such as uneven road surfaces cause incorrect estimation and reduce precision
Solution Approach 1:
The patent extracts and eliminates the external disturbance torque from the vehicle body movement model by separately estimating it from wheel speed variation. This allows the system to isolate and remove the harmful external disturbance component, enabling accurate vibration estimation even when external disturbances are present.
Solution Approach 2:
The patent introduces wheel speed variation as an intermediary parameter to estimate external disturbance torque. By using this intermediary measurement, the system can indirectly detect and compensate for external disturbances without directly measuring them, thereby improving estimation accuracy.
2Measurement precision
If external disturbance torque is estimated from wheel speed variation and input into the vehicle body movement model, then vibration estimation precision is improved, but wheel speed variation may not accurately represent external disturbance torque magnitude
Solution Approach 1:
The patent employs feedback by continuously monitoring wheel speed variation and using it to dynamically adjust the external disturbance torque estimation. This feedback mechanism allows the system to refine its estimation of disturbance torque magnitude based on actual observed wheel speed changes, compensating for the indirect nature of the measurement.
Solution Approach 2:
The patent changes the estimation approach by using wheel speed variation as a proxy parameter for external disturbance torque. Instead of directly measuring torque magnitude, the system transforms the problem into estimating torque based on readily available wheel speed data, which can then be fed into the vehicle body movement model.
3Measurement precision
If wheel speed information and correlation relationships are used to estimate vibrations, then precision is improved and external disturbance influence is excluded, but the method becomes more complex
Solution Approach 1:
The patent makes the wheel speed sensor serve multiple functions: it not only provides basic wheel speed information for vehicle control but also enables external disturbance torque estimation and vehicle body vibration estimation. By extracting multiple pieces of information from a single sensor, the system improves precision without proportionally increasing device complexity.
Solution Approach 2:
The patent enables the vehicle's existing wheel speed measurement system to serve the additional function of vibration estimation. By utilizing data already being collected for other purposes and applying correlation relationships, the system achieves enhanced estimation capability without requiring separate dedicated sensors or measurement systems.
Data Source
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AI summary
Computing sections (31, 32) compute an average front-wheel speed VwF=(VwFL+VwFR)/2 and an average rear wheel speed VwR=(VwRL+VwRR)/2, and then the resulting values (VwF and VwR) are passed through band-pass filtering sections (33, 34) to extract only a component near a vehicle body resonance frequency, respectively, thus acquiring a vibration component (fVwF) of the front wheel speed (VwF) near the vehicle body resonance frequency and a vibration component (fVwR) of the rear wheel speed (VwR) near the vehicle body resonance frequency, the vibration components being representative of a vehicle body vibration. Computing sections (35, 36) are adapted to determine, from the resulting values (fVwF and fVwR), a back-and-forth displacement (Xtf) of the front wheels and a back-and-forth displacement (Xtr) of the rear wheels, the dis placements being representative of the vehicle body vibration; to determine, from the resulting values (Xtf and Xtr), the up-and-down dis placement of a portion above a front axle and the up-and-down displacement of a portion above a rear axle, the up-and-down displacements being caused by the vehicle body vibration, on the basis of the inherent relations between the back-and-forth displacement and the up-and-down displacement of the front wheels and the rear wheels, the relations being determined by the geometry of a suspension; to estimate the vehicle body vibration (an up-and-down bounce speed (dZv) and a pitch angular velocity (d8p)) from the front and rear up-and-down displacements of the vehicle body; and to determine an amount of driving and braking force compensation (L'i Td) which is necessary to alleviate the vehicle body vibration.