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A Suspension Control System Adaptive To Detected And Estimated Road Profiles

IP.com Disclosure Number: IPCOM000029077D
Publication Date: 2004-Jun-15
Document File: 2 page(s) / 26K

Publishing Venue

The IP.com Prior Art Database

Abstract

In a semi-active or an active suspension system, both vehicle body and wheels are needed to be controlled for achieving the so-called ride comfort performance (body performance) and handling performance (wheel performance). Due to the inherent performance limitation, the suspension controls need to balance the body performance (usually at around 1 Hz frequency range) and wheel performance (usually at around 10 Hz frequency range), and those two performances are in conflict with each other. A method is proposed here to use suspension height sensor signals to estimate and detect the road disturbance (the road vertical profiles) and vehicle body and wheel states, and based on the frequency content of the road disturbance to adjust the suspension actuation command so as to achieve body performance (from 1 Hz up to the middle frequency range of about 4 Hz), on-demand wheel performance. If the detected and estimated road profile includes frequency contents higher than the so-called harshness frequency (for example, above 12 Hz), the suspension control is turned off such that the body performance is not worse than the performance of the passive suspensions.

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A Suspension Control System Adaptive To Detected And Estimated Road Profiles

In a semi-active or an active suspension system, both vehicle body and wheels are needed to be controlled for achieving the so-called ride comfort performance (body performance) and handling performance (wheel performance). Due to the inherent performance limitation, the suspension controls need to balance the body performance (usually at around 1 Hz frequency range) and wheel performance (usually at around 10 Hz frequency range), and those two performances are in conflict with each other.

A method is proposed here to use suspension height sensor signals to estimate and detect the road disturbance (the road vertical profiles) and vehicle body and wheel states,  and based on the frequency content of the road disturbance to adjust the suspension actuation command so as to achieve body performance (from 1 Hz up to the middle frequency range of about 4 Hz), on-demand wheel performance. If the detected and estimated road profile includes frequency contents higher than the so-called harshness frequency (for example, above 12 Hz), the suspension control is turned off such that the body performance is not worse than the performance of the passive suspensions.

Method

Ohsaka(US6298293) and Ohsaka et al(US5987367) teach a state estimation that is achieved using a quarter car model and is then used for a suspension control. Such a system uses a accelerometer to estimate suspension height. Our approach here works in the opposite direction: use suspension height sensor signals to detect and estimate acceleration, then estimate wheel states and road profile. The wheel state and road profile cannot be obtained from Ohsakaand Ohsaka et al. Although the estimation using quarter model is only precise when the vehicle is in heave motion, the approach here can be extended to include full car model for other motions.

After the body and wheel states are estimated, several control commands are computed from the body and wheel states based on the performance preference: for example, one for achieving good body performance around 1 Hz, on for achieving limited performance up to 4 Hz, one for achieving good wheel performance around 10 Hz.

The frequency content detection of the estim...