Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Vehicle subsystem or accessory control
Reexamination Certificate
1998-02-03
2001-01-16
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Vehicle subsystem or accessory control
C280S005507
Reexamination Certificate
active
06175792
ABSTRACT:
TECHNICAL FIELD
The present invention is directed to active roll control for a vehicle and is particularly directed to an apparatus and method for improving the dynamic response of an active roll system.
BACKGROUND OF THE INVENTION
Vehicle suspension systems have as their goal the control of chassis motion during vehicle operation. One operating motion characteristic, which is controlled by known suspension systems, is chassis roll. A vehicle experiences chassis roll during a turning maneuver. During chassis roll, the chassis tilts or “rolls” about the vehicle's fore-to-aft axis toward an outside direction of the turn.
It is known to counteract the roll effect of the chassis by providing an opposing force to the chassis. Several methods are known to apply the opposing force. One method includes applying a chassis lifting force via corner actuators located on the vehicle side that is on the outside of the turn and/or a chassis lowering force via corner actuators located on the vehicle side that is on the inside of the turn.
Another known method is to utilize a stabilizer bar that extends laterally across the vehicle. The stabilizer bar, which is also known as a roll-control bar, acts as a torsion spring to apply the opposing force. Further, it is known to vary the opposing force that the stabilizer bar applies to the chassis. One way to vary the opposing force is to utilize and control one or more hydraulic actuators in the connection of the stabilizer bar. An example of such a system is shown in U.S. Pat. No. 5,362,094 to Jensen.
To determine the amount of roll-opposing force to be applied to the chassis, such active suspension systems require an indication of lateral acceleration to which the vehicle is subjected during the turning or cornering maneuver. In one known system, an estimated value of lateral acceleration is calculated. The lateral acceleration calculation requires a sensory input from a steerable road wheel angle sensor, a sensory input from a vehicle velocity sensor, and the value of the vehicle wheel base dimension. In one example, the road wheel angle sensor is a steering shaft angle sensor and the vehicle velocity sensor is a drive-train (e.g., transmission) sensor.
The accuracy of the calculated estimate is dependent upon the accuracy of the relationship of the road wheel angle sensor and the vehicle velocity sensor to the actual lateral acceleration being experienced by the vehicle. The signals from the road wheel angle sensor and the vehicle velocity sensor may not accurately reflect the actual lateral acceleration experienced due to terrain conditions over which the vehicle is being driven. For example, driving the vehicle on a low traction surface may result in some amount of road wheel slippage. The calculated lateral acceleration, in this wheel slippage example, would not equal the actual lateral acceleration experienced by the vehicle.
Other known systems have a physical lateral acceleration sensor mounted to the vehicle and which provides a signal indicative of sensed actual lateral acceleration. However, the signal provided by the lateral acceleration sensor may include high frequency components resulting from road noise. One solution for eradicating such high frequency noise is to digitally low-pass filter the output signal from the acceleration sensor. However, use of a low-pass filter introduces a phase lag into the control system and thereby degrades the system's performance by reducing the system's bandwidth and the system's ability to quickly respond to steering maneuvers.
SUMMARY OF THE INVENTION
The present invention includes an apparatus for providing a weighted signal indicative of acceleration of an object. Means provides a first signal indicative of object acceleration. Means calculates a weighting factor using the first signal. Means multiplies the first signal by the weighting factor to provide the weighted signal.
In accordance with another aspect, the present invention includes an apparatus for providing an output signal indicative of a vehicle operating parameter. Sensor means senses the operating parameter and provides a first signal indicative thereof. Estimator means estimates the operating parameter and provides a second signal indicative thereof. Means processes the first and second signals to provide the output signal. The means for processing includes: means for determining first and second weighting factors for the first and second signals, respectively, using at least portions of the first and second signals, means for modifying the first and second signals using the first and second weighting factors to provide first and second modified signals, and means for combining the first and second modified signals to provide the output signal.
In accordance with another aspect, the present invention includes an active roll control suspension system for controlling chassis roll of a vehicle. Force application means applies force to the chassis. Control means controls the force application means in response to at least one operating parameter signal indicative of a vehicle condition. Means provides an acceleration signal to the control means as an operating parameter signal. The means for calculating an acceleration signal includes: means for providing a first signal indicative of acceleration, means for providing a weighting factor using the first signal, means for multiplying the first signal by the weighting factor to provide a weighted signal, and means for utilizing the weighted signal as a component to provide the acceleration signal.
In accordance with another aspect, the present invention includes an active vehicle suspension system for controlling chassis roll of a vehicle. Force application means applies force to the chassis. Control means controls the force application means in response to at least one operating parameter signal indicative of a vehicle condition. Means provides the operating parameter signal to the control means. The means providing the operating parameter signal includes sensor means for sensing the operating parameter and for providing a first signal indicative thereof. The means for providing includes estimator means for estimating the operating parameter and for providing a second signal indicative thereof. The means for providing also includes means for processing the first and second signals to provide the operating parameter signal. The means for processing includes: means for determining first and second weighting factors for said first and second signals, respectively, using at least portions of the first and second signals, means for modifying the first and second signals using the first and second weighting factors to provide first and second modified signals, and means for combining the first and second modified signals.
In accordance with yet another aspect, the present invention includes a vehicle suspension control apparatus having a controllable actuator for controlling at least one suspension characteristic in response to a control signal. Means senses lateral acceleration of the vehicle and provides a sensed lateral acceleration signal indicative thereof. Means estimates lateral acceleration of the vehicle and provides an estimated lateral acceleration signal indicative thereof. Means blends the sensed lateral acceleration signal and the estimated lateral acceleration signal to provide the control signal so that the control signal is initially responsive to the estimated lateral acceleration signal and subsequently responsive to the sensed lateral acceleration signal.
In accordance with still a further aspect, the present invention includes a method for providing a weighted signal indicative of acceleration of an object. A first signal indicative of object acceleration is calculated. A weighting factor is provided using the first signal. The first signal is multiplied by the weighting factor to provide the weighted signal.
In accordance with yet a still further aspect, the present invention includes a method for providing an output signal indicative of a vehicle oper
Ghaphery Abraham
Jones Neil
Cuchlinski Jr. William A.
Gibson Eric M.
Tarolli, Sundheim, Covell Tummino & Szabo L.L.P.
TRW Inc.
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