Data processing: measuring – calibrating – or testing – Measurement system – Orientation or position
Reexamination Certificate
1999-03-23
2001-07-10
Assouad, Patrick (Department: 2857)
Data processing: measuring, calibrating, or testing
Measurement system
Orientation or position
C701S038000, C073S514010
Reexamination Certificate
active
06259999
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method and arrangement for determining an inertial state of a vehicle.
BACKGROUND INFORMATION
German Patent Application No. 196 09 717 describes an arrangement for detecting roll-over occurrences in vehicles. In case roll-over of a vehicle occurs, all passenger protection devices installed in the vehicle must be triggered promptly, including, for example, roll bars, belt tighteners and various airbags. To enable prompt triggering of all of these protection devices, it must be detected as soon as possible whether rotations of the vehicle about its vertical axis, its longitudinal axis or its transverse axis lead to a roll-over. Incorrect decisions on a roll-over occurrence must be ruled out insofar as possible so that the restraint devices are not triggered when, for example, the vehicle is on a steep slope or undergoes slow rotational occurrences during travel through curves. To prevent incorrect decisions from occurring in the roll-over sensing, the inertial state, i.e., the initial state of the vehicle relative to the earth-based coordinate system, must be known. Dynamic vehicle movements such as travel through curves or braking or acceleration procedures can have disruptive effects in determining the inertial state.
SUMMARY OF THE INVENTION
An object of the invention is to specify a method and an arrangement for determining the inertial state of a vehicle, disruptive effects due to dynamic vehicle movements being ruled out to the greatest possible extent.
Initially, the accelerations of the vehicle in the direction of its longitudinal, transverse and vertical axes are measured. Then, the magnitude of an acceleration vector resulting from the three acceleration components is formed and this magnitude is compared through threshold decisions with a window that is delimited by a threshold lying above and a threshold lying below the gravitational acceleration. The current positional angle of the vehicle with respect to its longitudinal axis and/or the current course angle with respect to its transverse axis is then determined only if the magnitude of the acceleration vector lies inside the window. However, if the magnitude of the acceleration vector lies outside the window, then a previously determined course angle with respect to the longitudinal axis and/or course angle with respect to the transverse axis is retained.
In this method or rather a corresponding arrangement for carrying out this method, dynamic acceleration components of the vehicle are ruled out with the aid of the window function when determining the inertial state. The course angles of the inertial state can then be correctly measured with the three acceleration sensors if the vehicle is either not moving at all or is moving uniformly. If the vehicle is subject to dynamic state changes, then no new current course angles are determined; instead, one falls back on previously determined course angles that are uninfluenced by dynamic position changes.
It is advantageous that the upper threshold of the window is about 10% greater and the lower threshold about 10% less than gravitational acceleration. Interfering quantities in determining the inertial state can be suppressed even more effectively if the threshold decisions are performed with respectively two acceleration vectors formed one after another in time. By forming the current course angle recursively from a component of a previously determined course angle and a component of the course angle derived from the currently measured accelerations, short-term disruptions can be suppressed very well in an advantageous manner.
Roll-over occurrences are very fast state changes of the vehicle that can be best detected with rate of rotation measurements. Based on the measured rates of rotation, the course angles are then derived through integration and it is decided based on these course angles whether a roll-over of the vehicle is occurring or not. So that dynamic vehicle movements uncritical to a roll-over occurrence do not also enter into the integration of the measured rates of rotation and the resulting course angles do not lead to an incorrect decision concerning a roll-over occurrence, it is useful to not begin integration of the rates of rotation prior to the availability of the inertial course angles derived according to the present invention.
REFERENCES:
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Assouad Patrick
Kenyon & Kenyon
Robert & Bosch GmbH
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