Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication
Reexamination Certificate
1999-05-21
2001-12-11
Louis-Jacques, Jacques H. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
C701S070000, C303S146000, C303S198000, C073S17800T
Reexamination Certificate
active
06330496
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method of controlling the driving performance of a vehicle, using tire sensors to determine forces that act on the individual vehicle wheels.
BACKGROUND OF THE INVENTION
A method of this type is disclosed in EP Patent No. 0 444 109 B1, for example. This publication describes a method and a device for determining tire prints, for the conversion thereof into forces which act on the tires and for improvement of the driving performance of the vehicle. Beside tire sensors which sense the tire contact, there are provided still other sensors, such as sensors for sensing the wheel circumferential speeds, the steering angle of the wheels, the position of the wheel suspensions and the center-of-gravity acceleration. The control method discloses sensing the forces and torques which act on the respective tire by way of tire print sensors. The forces and torques found are used, along with the other sensor means, to control the movement of the automotive vehicle. The above publication does not disclose which physical quantity is the actual control quantity used by the method.
It is state of the art, for example, to perform yaw torque control where a nominal yaw rate is compared with an actual yaw rate and, in the event of a discrepancy of the actual yaw rate from the nominal yaw rate, this difference is converted into control signals for defined correction elements. Operation of the correction elements will then cause the actual yaw rate to approach the nominal yaw rate. When, according to the above-mentioned publication, a defined physical quantity such as the rotational speed of the wheels shall be controlled selectively, it is assumed that this speed is also the control quantity. Initially, the forces which act on the wheels must be processed to calculate a nominal speed of the wheels. Matters are similar with respect to the steering angle or the position of the wheel suspensions of the wheels. The signals of the tire contact sensors are each time converted into the physical quantity respectively being controlled in order to compare an actual vehicle performance with a nominal vehicle performance. This necessitates a major expenditure in calculations because the physical quantity underlying the control cannot be determined directly, but only in a complicated fashion by converting tire contact signals into tire forces and torques and by further processing them into the physical quantity. Such a complicated processing of signals necessitates a considerable length of real time, thereby entailing a long reaction time until control intervention. The actual physical quantities which result at the end of such a complicated calculation are no longer relevant at the time they are calculated: The control quantity of the method will suffer because the control intervention which is performed with delay only may possibly not satisfy the demands of the actual driving situation.
Therefore, an object of the present invention is to provide a method of controlling the driving performance of a vehicle, utilizing tire sensors, which method permits a quickest possible reaction to a critical driving performance by way of a controlling intervention.
SUMMARY OF THE INVENTION
This object is achieved by making the forces acting on the tires the control quantity of a control circuit. The principle of the present invention is based on the following reflection: The tire sensors permit the simple calculation of forces and torques in longitudinal, transverse and vertical directions. Thus, calculation of these forces and torques requires only little time. It is therefore advisable to take especially these forces into account as a control quantity of the driving performance in order to perform a control intervention in a most direct manner.
Of course, there may be still other physical quantities which are taken into account in the calculation of the nominal performance of the vehicles. The preset nominal value always determines in first line the direction in which the control quantity is adjusted. Therefore, the preset nominal value can pass a greater loop of calculating operations and need not always be as absolutely current as is advisable for the actual value of the driving performance. The direction in which the control quantity is adjusted, as time goes by, will not vary so greatly as the actual quantity that is characteristic of the driving conditions.
Nominal forces in a longitudinal direction or also transverse direction, such as during cornering, which are determined by way of the method of the present invention may be converted into brake pressure variations or absolute brake pressures, for example. In hydraulic brake systems, they may also be converted into valve actuation periods, or current intensities when proportional valves are used. It is also possible to vary the engine drive torque to control driven wheels with respect to nominal forces. In this arrangement, however, the forces which act on the tires always remain the control quantity which dictates the intervention into the wheel brakes or the engine drive torque.
To determine nominal forces, the actual forces can be processed along with other input quantities. For the reasons mentioned hereinabove, it is of no significance with respect to the control quality that this calculating operation requires a longer real time.
Thus, a control method according to the present invention for yaw torque control would be such that a nominal yaw torque is calculated under certain circumstances, however, no actual yaw torque is sensed by a yaw rate sensor. On the contrary, a nominal yaw torque is converted into nominal forces which would have to act on the respective vehicle tire if the nominal yaw torque were coincident with the actual yaw torque. The actual forces which act on the vehicle tire will then be controlled to approach the nominal forces.
In an electronic brake force distribution, for example, the actual forces on the front wheels can be taken into account for determining the nominal forces for the respective rear wheels.
Further input quantities which are taken into account for the determination of the nominal quantities could be individual wheel speeds and a vehicle reference speed, for example. These input quantities could typically be sensed by way of wheel sensors or by a corresponding configuration of the tire sensors.
The present invention will now be explained in detail by describing two embodiments in two Figures.
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Fennel Helmut
Latarnik Michael
Continental Teves AG & Co. oHG
Louis-Jacques Jacques H.
Rader & Fishman & Grauer, PLLC
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