Vehicle Control System Using Delayed Front Wheel Speed for Rear Estimation
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Solution Overview
Problem
Wheel speed sensors for rear wheels connected to a differential gear exhibit low precision in estimating vehicle vibrational states due to little change in wheel speed sensor values during axle tilting, leading to reduced vibration damping performance.
Innovation Solution
A vehicle control device that delays the front wheel speed detected by front wheel speed sensors to estimate the rear wheel speed, using the sizes of the amplitudes of the frequencies of both speeds as frequency scalar quantities to calculate the damping force of variable-damping-force shock absorbers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If rear wheel speed sensors connected to differential gear are used to estimate vehicle vibrational state, then device complexity is reduced, but measurement precision deteriorates due to little change in wheel speed sensor values during axle tilting
Solution Approach 1:
The patent uses front wheel speed sensor data as an intermediary to estimate rear wheel speed. Instead of directly using rear wheel speed sensors connected to the differential gear (which provide poor measurement during axle tilting), the system delays and processes front wheel speed data to serve as a proxy for rear wheel speed, thereby maintaining measurement precision without adding complex sensor configurations.
Solution Approach 2:
The patent creates a copied representation of rear wheel speed by delaying front wheel speed sensor data. This copied speed signal replicates the essential characteristics of actual rear wheel speed without requiring physical rear wheel speed sensors, thus solving the measurement precision problem while keeping the device configuration simple.
2Measurement precision
If front wheel speed is delayed to estimate rear wheel speed, then measurement precision is improved, but loss of time occurs due to the delay
Solution Approach 1:
The patent transforms the wheel speed signal by applying a time delay parameter that corresponds to the wheelbase distance. This parameter change allows the front wheel speed data to be converted into an estimate of rear wheel speed, maintaining precision while the time loss is accepted as a necessary trade-off for achieving accurate vibrational state estimation.
Solution Approach 2:
The system performs preliminary processing of front wheel speed data by delaying it to predict future rear wheel speed conditions. This preliminary action allows the control system to prepare damping force adjustments in advance, compensating for the time delay and maintaining effective vibration damping performance.
3Adaptability or versatility
If damping force control is calculated based on frequency scalar quantities, then adaptability to phase deviations is improved, but device complexity increases due to frequency analysis requirements
Solution Approach 1:
The patent implements dynamic damping force control by calculating control amounts based on frequency scalar quantities rather than fixed parameters. This dynamic approach allows the system to adapt to varying phase deviations and driving conditions, maintaining versatility while the processing complexity is managed through efficient frequency analysis algorithms.
Data Source
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AI summary
Rear wheel speed is estimated by delaying a front wheel speed detected by front wheel speed sensors (5FL, 5FR), and the detected front wheel speed and the size of the amplitude of the frequency of the estimated rear wheel speed are taken as frequency scalar quantities used to calculate a damping force control amount for S/As (3).