Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Vehicle subsystem or accessory control
Reexamination Certificate
1999-09-07
2001-11-06
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Vehicle subsystem or accessory control
C701S001000, C188S266100, C188S266200, C188S379000, C267S140140, C267S140150, C280S005515, C280S005519
Reexamination Certificate
active
06314353
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a resilient support mechanism for resiliently supporting the component structure of a wheeled vehicle. More particularly, the present invention is concerned with a control system for a resilient support mechanism such as a suspension mechanism disposed between an unsprung mass and a sprung mass of the wheeled vehicle for controlling a damping force or a damping coefficient of a shock absorber or damper device assembled therein.
2. Discussion of the Prior Art
In a conventional suspension mechanism of a wheeled vehicle, an amount of movement state of a sprung mass or an unsprung mass of the vehicle is detected to determine a target damping force or a target damping coefficient on a basis of the detected amount of movement state thereby to adjust the damping force or damping coefficient of a shock absorber or damper device assembled in the suspension mechanism to the target damping force or damping coefficient. Disclosed in Japanese Patent Laid-open Publication No. 10-119528 is a control system for the suspension mechanism in which the well-known sky nook theory is applied to determine a target damping coefficient based on acceleration of the sprung mass and relative velocity of the sprung mass to the unsprung mass in a vertical direction.
In the suspension mechanism described above, however, the damping force of the shock absorber or damper device is defined by the product of the relative velocity of the sprung mass to the unsprung mass and the damping coefficient, while the damping coefficient changes nonlinearly in accordance with the relative velocity of the sprung mass. For this reason, the design of the control system becomes very complicated. For example, it has been considered to estimate a plant indicative of a state space in the suspension mechanism for design of the control system. However, as the plant is bilinear, it is obliged to apply an approximate law to a range where a control input would not be realized in the resilient support mechanism such as a suspension mechanism, even if a linear control theory was applied to the bilinear system. For this reason, a control specification (a norm condition) given at a design stage may not be theoretically satisfied. As a result, the control input becomes discontinuous to cause a sense of incongruity in control of the suspension mechanism.
SUMMARY OF THE INVENTION
It is, therefore, a primary object of the present invention to provide a control system for a resilient support mechanism such as a vehicle suspension mechanism capable of enhancing riding comfort of the vehicle without causing any sense of incongruity in control of the suspension mechanism.
According the present invention, the object is accomplished by providing a control system for a resilient support mechanism including a damper or a shock absorber assembled therein for resiliently supporting thereon an object, wherein a control theory capable of providing a specification for design of the control system in a predetermined frequency range is applied to a nonlinear plant to calculate a target damping force and to adjust an actual damping force of the damper or shock absorber to the calculated target damping force. In a practical embodiment of the present invention, the resilient support mechanism is in the form of a resilient support mechanism in a wheeled vehicle for resiliently supporting a component member of the vehicle such as a vehicle body, a prime mover or the like. In the control system, either one of a nonlinear H
∞
state feedback control, a nonlinear H
∞
output feedback control or a nonlinear H
∞
control using a Kalman filter may be applied as the control theory.
With the control system, a norm condition given at a design stage is satisfied even in a resilient support mechanism in the form of a bilinear system such as a suspension mechanism of a wheeled vehicle so that a control input continuously changes to control a damper in the resilient support mechanism without causing any sense of incongruity in control of the support mechanism.
In the case that the present invention is applied to a suspension mechanism of a wheeled vehicle, it is preferable that the control system comprises detection means for detecting a state amount related to vertical movement of the sprung mass and unsprung mass members, memory means for memorizing a positive definite symmetric solution obtained on a basis of the control theory, and calculation means for calculating the target damping force based on the memorized positive definite symmetric solution and the detected state amount. Alternatively, the control system may comprises detection means for detecting a portion of a plurality of state amounts related to vertical movement of the sprung and unsprung mass members, estimation means for estimating the other portion of the state amounts by using an observer, memory means for memorizing a positive definite symmetric solution obtained on a basis of the control theory, and calculation means for calculating the target damping force based on the memorized positive definite symmetric solution, the detected state amount and the estimated state amount. In this case, it is desirable that a vertical displacement amount of a tire of a road wheel, a relative vertical displacement amount of the sprung mass member to the unsprung mass member, a vertical velocity of the unsprung mass member and a vertical velocity of the sprung mass member are detected as the state amounts.
With the above arrangement, a norm condition given at a design stage is satisfied even in such a bilinear control system described above so that a control input continuously changes to enhance running stability and riding comfort of the vehicle without causing any sense of incongruity in control of the suspension mechanism.
According to an aspect of the present invention, there is provided a control system for a resilient support mechanism such as a suspension mechanism of a wheeled vehicle wherein a damping coefficient of a damper assembled in the resilient support mechanism is divided into a linear portion and a nonlinear portion, and wherein the control system comprises first calculation means for calculating the nonlinear portion of the damping coefficient on a basis of a nonlinear H
∞
control theory and second calculation means for calculating a target damping coefficient based on synthesis of the linear portion of the damping coefficient and the calculated nonlinear portion, in the control system, a target damping force may be calculated by detecting or estimating a relative velocity of a sprung mass member to an unsprung mass member and multiplying the relative velocity by the calculated target damping coefficient.
According to another aspect of the present invention, there is provided a control system for a resilient support mechanism wherein a damping coefficient of a damper assembled in the support mechanism is divided into a linear portion and a nonlinear portion, and wherein each gain of the linear portion and nonlinear portion is defined in such a manner that a target damping force is determined in a range of an actual damping force produced by the damper. In the control system, it is preferable that the linear portion of the damping coefficient of the damper is defined to be located between a minimum damping force of the damper and a maximum damping force of the damper. With the control system, a control specification or a norm condition given at a design state is satisfied in such a manner that a control input continuously changes to control the support mechanism without causing any sensor of incongruity.
According to a further aspect of the present invention, there is provided a control system for a resilient support mechanism wherein a damper assembled in the support mechanism is constructed to be switched over at plural steps, wherein a damping coefficient of the damper is divided into a linear portion and a nonlinear portion, and wherein the linear portion of the damping coefficient is d
Kamimura Ichisei
Ohsaku Satoru
Cuchlinski Jr. William A.
Mancho Ronnie
Oliff & Berridg,e PLC
Toyota Jidoshi Kabushiki Kaisha
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