Data processing: measuring – calibrating – or testing – Measurement system – Speed
Reexamination Certificate
1998-10-29
2001-12-18
Shah, Kamini (Department: 2857)
Data processing: measuring, calibrating, or testing
Measurement system
Speed
C701S070000, C701S078000, C180S274000
Reexamination Certificate
active
06332115
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a velocity calculating device which is capable of estimating momentary velocity of a vehicle precisely when it collides and a hood raising system which is capable of raising a hood of the vehicle on the basis of the momentary velocity thereby to protect an object from being damaged.
2. Description of Related Art
A conventional hood raising system operates as follows. When the vehicle on traveling collides against the object, then the system detects the collision by a touch sensor and simultaneously operates to raise a hood arranged on the front side of the vehicle to prevent the object from colliding with rigid components, such as an engine, through the intermediary of the hood, thereby protecting the object.
In the above hood raising system, a velocity calculating device calculates an average velocity at intervals of predetermined times as a standard on the basis of velocity pulse signals generated from a vehicle velocity sensor. Also, the system is so constructed as to raise the hood when the so-calculated average velocity is within a predetermined range as a standard, thereby distinguishing from normal collisions.
SUMMARY OF THE INVENTION
In the conventional hood raising system, however, it is supposed that the detected velocity has luck reliability due to a large error. For example, if a brake pedal is stepped rapidly to lock vehicle wheels, then the above-mentioned average velocity would become zero.
It is therefore an object of the present invention to provide a velocity calculating device which can estimate a precise momentary speed and also provide a hood raising system which can raise a hood on the vehicle on the basis of the momentary velocity thereby to protect an object in front of the vehicle.
The above object of the present invention described above can be accomplished by a velocity calculating device for a vehicle comprising:
an average velocity calculating unit which inputs velocity pulse signals representing rotating speed of wheels of the vehicle to calculate an average velocity of the vehicle at intervals of a first period as a standard;
an acceleration calculating unit for calculating an acceleration of the vehicle at intervals of a second period, on the basis of the pulse signals;
a momentary velocity calculating unit for calculating a first momentary velocity at intervals of the first period, on the basis of the average velocity and the acceleration calculated;
an inputting unit which inputs a signal to command an output of calculation results of velocity of the vehicle;
a passing-time measuring unit for measuring a passing time from beginning of the input of velocity pulse signals till the input of the signal to command the output of calculation results; and
a momentary velocity estimating unit for estimating a second momentary velocity of the vehicle at a point of time when the signal to command the output of calculation results is inputted, on the basis of the passing time measured by the passing-time measuring unit, the first momentary velocity calculated by the momentary velocity calculating unit and the acceleration calculated by the acceleration calculating unit.
With the above-mentioned arrangement, it is possible to obtain the precise momentary velocity.
In the present invention, preferably, the velocity calculating device further comprises:
a wheel condition judging unit which judges a wheel-locking condition due to the vehicle's rapid braking and a wheel-slipping condition due to the vehicle's rapid accelerating, on the basis of the velocity pulse signals; and
an acceleration selecting unit for selecting either one of an acceleration under the wheel-locking condition, an acceleration under the wheel-slipping condition and the acceleration calculated by the acceleration calculating unit, in accordance with a wheel condition judged by the wheel condition judging unit;
wherein the momentary velocity estimating unit calculates the second momentary velocity at the point of time when the signal to command the output of calculation results is inputted, by making use of the acceleration selected by the acceleration selecting unit.
With the above arrangement, since the velocity calculating device of the invention does estimate the second momentary velocity at a point of time when the signal to command the output of calculation results is inputted while selecting the acceleration corresponding to the wheel condition, it is possible to obtain the it is possible to obtain the precise momentary velocity corresponding to the wheel condition.
In the above-mentioned arrangement, more preferably, the velocity calculating device further comprises:
a load condition judging unit for judging a load condition during the vehicle's traveling, on the basis of temperature of outside air and existence or non-existence of rain drops; and
an acceleration determining unit for determining the acceleration under the wheel-locking condition or the wheel-slipping condition in accordance with the load condition judged by the load condition judging unit.
In this case, since the velocity calculating device of the invention does estimate the second momentary velocity at a point of time when the signal to command the output of calculation results is inputted while selecting the acceleration corresponding to the load condition, it is possible to obtain the precise momentary velocity corresponding to the load condition.
According to the invention, it is also preferable that the wheel condition judging unit comprises a locking condition judging unit which calculates a pulse period in proportion to the vehicle's velocity estimated in case of the vehicle's rapid braking, and which judges that the vehicle is under the wheel-locking condition, on condition that the velocity pulse signal at present is not inputted within the pulse period in proportion to the estimated vehicle's velocity.
In this case, it is possible to judge that the wheels are under the locked condition, certainly.
According to the invention, it is also preferable that the wheel condition judging unit comprises a slipping condition judging unit which calculates a pulse period in proportion to the vehicle's velocity estimated in case of the vehicle's rapid accelerating, and which judges that the vehicle is under the wheel-slipping condition, on condition that the velocity pulse signal at present is inputted within a period shorter than the pulse period in proportion to the estimated vehicle's velocity.
In this case, it is possible to judge that the wheels are under the slipping condition, certainly.
According to the invention, it is also preferable that the wheel condition judging unit comprises a slipping condition judging unit which calculates an average velocity of the vehicle at predetermined intervals and also calculates the vehicle's acceleration on the basis of both of the previously calculated average velocity and the present average velocity, and which judges that the vehicle is under the wheel-slipping condition, on condition that the so-calculated vehicle's acceleration exceeds a predetermined value.
Also in this case, it is possible to judge that the wheels are under the slipping condition, certainly.
According to the present invention, there is also provided a hood raising apparatus for raising a hood on a front side of a vehicle, the hood raising apparatus comprising:
a collision detecting unit arranged on a front side of the vehicle, for detecting a collision of the vehicle on traveling;
a velocity calculating device which inputs a collision signal, which has been generated from the collision detecting unit, as a signal to command an output of calculation results of velocity of the vehicle, the velocity calculating device comprising:
an average velocity calculating unit which inputs velocity pulse signals representing rotating speed of wheels of the vehicle to calculate an average velocity of the vehicle at intervals of a first period as a standard;
an acceleration cal
Nobusawa Hisashi
Takai Hideo
McDermott & Will & Emery
Nissan Motor Co,. Ltd.
Shah Kamini
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