Measuring and testing – Simulating operating condition – Marine
Patent
1999-01-14
2000-12-12
Raevis, Robert
Measuring and testing
Simulating operating condition
Marine
G01M 1500
Patent
active
061582743
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a method of determining quantities describing the driving behavior of a four-wheel vehicle.
BACKGROUND OF THE INVENTION
Series vehicles of medium and high price categories are increasingly equipped with systems that enhance active safety in addition to passive safety systems, such as safety belts, airbags, deformation zones, and side-impact protection systems. Active safety systems include, for example, anti-lock systems, systems for traction slip control and, most recently, systems for yaw torque control during cornering. Systems for increasing active safety require, apart from an electronic controller which furnishes specifications for intervention into the brake system, additional components in the vehicle which permit sensing the driving condition, on the one hand, and control intervention, on the other hand. Such vehicle components include, sensors to measure the yaw velocity or the transverse vehicle acceleration render systems which enhance the active safety. Unfortunately these sensors increase vehicle costs. Therefore, an important development aim is to minimize costs for systems of this type. One related objective is, for example, that condition variables which can only be measured by expensive sensors shall be reproduced by signals of less expensive sensors or sensors which are already provided in the system.
German patent application No. 42 16 301 discloses a method that obviates the need for a yaw rate sensor to determine the yaw velocity of a vehicle, i.e., the angular speed about the vertical vehicle axis. Instead of a yaw rate sensor, two axially offset transverse acceleration sensors are mounted into the vehicle. The signals of the sensors provide values for the front and rear transverse accelerations of the vehicle. This renders possible in a simple manner to determine the yaw angle acceleration and the transverse vehicle acceleration without taking a rolling motion into consideration. When the rolling motion of a vehicle during cornering is additionally taken into account, this complicates the entire calculating operation but finally furnishes a result.
An object of the present invention is to provide a method which permits further reducing the sensor means on the vehicle and thereby offers the possibility of reducing the cost for systems used to increase the active safety, especially yaw torque control systems.
Thus, the principle of the present invention is to eliminate even the need for transverse acceleration sensors by evaluating the different wheel rotational speeds of two wheels arranged on each one vehicle side. However, the selection of these wheels shall be bound to defined criteria, and it is important that the selected wheels are not exposed to excessive slip.
Attempts have been made to replace transverse acceleration sensors by evaluating the wheel rotational speeds either on the two front wheels or the two rear wheels. It has been found that the calculating methods employed mirror reality only if both wheels are in a stable driving condition, i.e., have no excessive slip. However, when a pair of wheels is invariably predetermined, it relatively frequently occurs that one of the wheels must undergo slip control. A method of determining driving conditions as mentioned above would provide an only improper operation in such a case.
In the present invention, however, it is possible to take into account two suitable wheels of four different pairs of wheels for evaluating their rotational speeds. This means, the wheel pairs are either the two wheels of the front axle, the two wheels of the rear axle, or the respectively diagonally opposite wheels of the front and rear axles. Even during a slip control operation at least one of the four pairs of wheels mentioned is not concerned by the control. This implies that the reproduction of a yaw velocity and/or a transverse acceleration is successful even in unstable driving conditions when all four wheel rotational speeds offer to select two of them.
However, it should be checked for re
REFERENCES:
English translation of the International Preliminary Examination Report for PCT/EP97/00260.
Search Report of the German Patent Office Relating to German Patent Application 196 02 994.5.
Japanese Abstract 62-255871 (A) published Jul. 11, 1987.
Guo Limin
Herbst Ralf
Continental Teves AG & Co. OHG
Raevis Robert
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