Variable Damper Control via Front Wheel Acceleration Estimation
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Solution Overview
Problem
The existing vehicle suspension systems require four G sensors to implement Sky-hook control, which increases production costs due to the need for all sensors to be present, even though they cannot be positioned on a single plane, leading to unnecessary economic burden on consumers.
Innovation Solution
A method to control a variable damper by estimating the vertical acceleration of the rear wheel using the time delay in wheel motion between the front and rear wheels, allowing the rear-wheel variable damper to be controlled with only the front-wheel G sensor, reducing the number of parts needed in vehicle production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If four G sensors are installed at vehicle body and wheels to implement Sky-hook control, then the vibration isolation effect and ride comfort are improved, but the number of parts and production cost increase
Solution Approach 1:
The patent uses the motion state of the front wheel as a copy or reference to estimate the rear wheel's motion state. By applying time delay based on the known wheelbase distance and vehicle speed, the system reconstructs the rear wheel acceleration signal without physically installing a sensor there, thus reducing part count while maintaining control functionality
Solution Approach 2:
The patent introduces time delay as an intermediary parameter to transfer the motion information from the front wheel to the rear wheel position. The time delay value, calculated from wheelbase and vehicle speed, acts as a mediator that allows the control system to infer rear wheel conditions from front wheel measurements
2Measurement precision
If four G sensors are installed to achieve accurate Sky-hook control, then the control precision is improved, but the production cost and economic burden on consumers increase
Solution Approach 1:
The patent creates a virtual copy of the rear wheel acceleration signal by processing the front wheel sensor data through time delay and coordinate transformation. This copied signal is sufficiently accurate for Sky-hook control purposes, eliminating the need for expensive additional hardware sensors
Solution Approach 2:
The patent replaces the mechanical solution of installing physical sensors at all four wheels with a computational approach. By using algorithms that process front wheel data with time delay compensation, the system achieves the same measurement function without the additional mechanical sensors, thereby reducing cost
Data Source
AI summary
The present invention relates to a method of controlling a variable damper in a vehicle wherein a rear-wheel variable damper can be controlled by estimating a vertical acceleration value of a rear wheel based on the fact that there is a certain time delay in a wheel motion between front and rear wheels due to the wheelbase and vehicle speed. To this end, the method of the present invention comprises the steps of (a) detecting vehicle body accelerations other than a desired vehicle body acceleration of a vehicle body; (b) calculating the desired vehicle body acceleration based on the other detected vehicle body accelerations according to a geometric rule; (c) calculating vehicle body vertical velocities by filtering the vehicle body accelerations to eliminate DC offsets therefrom and integrating the filtered accelerations; (d) detecting accelerations of front right/left vehicle wheels; (e) calculating front wheel vertical velocities by filtering the detected accelerations of the front right/left wheels to eliminate DC offsets therefrom and integrating the filtered accelerations, and then calculating accelerations of rear wheels by time delaying the accelerations of the front wheels by a time interval taken while a road input to the front wheel is delivered to the rear wheel at a vehicle speed; and (f) calculating damper velocities based on the calculated vehicle body vertical velocities and the calculated vehicle wheel vertical velocities. Accordingly, the Sky-hook determination can be more accurately made. Further, since it is not necessary to use all the four sensors, the number of parts of vehicles can be reduced when mass-producing the vehicles. Consequently, the selling prices for finished vehicles can be lowered, and thus, an unnecessary economical burden cannot be imposed on the consumers.