JP2000035331A - Altitude meter for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an altitude meter for vehicles for measuring the altitude of the running vehicles accurately by correcting the error caused by conditions of acceleration of the vehicle, load, the number of passengers, quantity of gasoline, etc. SOLUTION: In an altitude meter for vehicles for calculating vehicle pitch angle based on the acceleration signal obtained from an acceleration meter attached to a vehicle 6 directing the input axis to the front and back direction of the vehicle 6 and multiplying the vehicle pitch angle and milage for measuring the altitude of the vehicle 6, distance measuring devices 3 and 4 for measuring the distance between the vehicle 6 and the road surface are placed with a distance in the front and back direction of the vehicle 6. Relative angle between the direction of front and back of the vehicle and the road surface is measured based on the difference of the distance data obtained by the distance measuring devices 3 and 4 and the altitude is calculated by correcting the vehicle pitch angle with the relative angle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle altimeter, and more particularly to a vehicle altimeter which corrects errors caused by acceleration, load, the number of passengers, the amount of gasoline, and other conditions of a vehicle. The present invention relates to a vehicle altimeter that measures an altitude of a vehicle.

[0002]

2. Description of the Related Art Conventionally, an altimeter for a vehicle is mounted on a vehicle by setting an input shaft of the accelerometer in a front-rear direction of the vehicle and mounting the accelerometer on a vehicle. 2. Description of the Related Art There is known an altimeter which measures a vehicle pitch angle, which is an inclination angle, and multiplies it by a traveling distance to measure an altitude. Hereinafter, this will be described with reference to FIG.

[0003] In FIG. 3, an accelerometer 10 has a single axis and is mounted in the front-rear direction of a vehicle 6. Attempting to measure the vehicle pitch angle measured from a horizontal plane, focusing on the acceleration applied to the vehicle. The vehicle pitch angle theta, the acceleration of gravity g, the acceleration of the vehicle 6, a _c, acceleration Sa of the sum of the acceleration a _c from the accelerometer 10 a = g · sinθ and the vehicle 6 can be obtained. The speedometer 20 obtains the speed Sv of the vehicle 6 from the rotation speed of the wheels of the vehicle 6.

The computing unit 30 detects the vehicle pitch angle θ of the vehicle 6 from the acceleration Sa output from the accelerometer 10 and the speed Sv of the vehicle output from the vehicle speed meter 20, and outputs the vehicle pitch angle signal and the speed signal of the vehicle speed meter 20. The vertical speed Vv = Vsin θ of the vehicle 6 is detected based on the output speed Sv, and the vertical speed signal is integrated to calculate an altitude difference between two points where the vehicle 6 has traveled (for details, see Japanese Patent Application Laid-Open No. 3-165265). Reference).

[0005]

The prior art altimeter for a vehicle described above assumes that the vehicle pitch angle θ is equal to the road surface inclination angle θ ₀ , and multiplies the vehicle pitch angle by the travel distance to obtain the altitude. I'm asking. However, the vehicle pitch angle θ varies depending on the acceleration / deceleration of the vehicle, the load, the number of passengers, the amount of gasoline, and other conditions, and is not necessarily equal to the road surface inclination angle θ ₀ . The relative angle is generated consisting δθ between the vehicle pitch angle theta and the road inclination angle theta _0. An error occurs in the elevation data due to the relative angle δθ.

The present invention has solved the above-described problem of measuring the altitude of a running vehicle with high accuracy by correcting errors caused by vehicle acceleration, cargo, the number of passengers, the amount of gasoline, and other conditions. A vehicle altimeter is provided.

[0007]

A vehicle pitch angle is calculated based on an acceleration signal obtained from an accelerometer 10 attached to the vehicle 6 with the input shaft being in the front-rear direction of the vehicle 6, and the vehicle pitch angle and the vehicle pitch angle are calculated. In a vehicular altimeter for measuring the altitude of the vehicle 6 by multiplying the distance by a travel distance, distance measuring devices 3 and 4 for measuring the distance between the vehicle 6 and the road surface are provided separately from each other in the front-rear direction of the vehicle 6 to measure distance. Based on the difference between the distance data obtained from the devices 3 and 4, the relative angle between the front-rear direction of the vehicle and the road surface is measured, and the vehicle altitude is calculated by correcting the vehicle pitch angle based on the relative angle and calculating the altitude. .

Claim 2: In the vehicle altimeter described in claim 1, the distance measuring devices 3 and 4 constitute a vehicle altimeter mounted on the front and rear portions of the vehicle. In a third aspect of the present invention, in the vehicle altimeter according to any one of the first and second aspects, the distance measuring device constitutes a vehicle altimeter which is an optical distance measuring device. Further, in the vehicle altimeter according to any one of the first and second aspects of the present invention, the distance measuring device constitutes a vehicle altimeter which is an ultrasonic distance measuring device.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. Reference numeral 1 denotes a vehicle speed sensor that measures the traveling speed of the vehicle 6. The vehicle speed sensor 1 is mounted on a vehicle 6, and a speed sensor that counts the number of rotations of wheels and obtains a speed based on the number is generally used.

Reference numeral 2 denotes a vehicle inclination angle calculation unit. The vehicle inclination angle calculation unit 2 uses the acceleration signal obtained from the accelerometer 10 attached to the vehicle 6 with the input shaft in the front-rear direction of the vehicle 6 and the vehicle speed signal obtained from the vehicle speedometer 20 attached to the vehicle 6. The pitch angle θ is calculated. 3 and 4
Is an optical distance measuring device for measuring the distance between the vehicle and the road surface, and is provided at a distance L from each other in the front-rear direction of the vehicle 6. In the embodiment shown in FIG. 2, a front optical distance measuring device 3 is attached to a front portion of a vehicle 6, and a rear optical distance measuring device 4 is attached to a rear portion. The front optical distance measuring device 3 emits light to the road surface, receives the reflected light, and measures the front height Fh between the vehicle 6 and the road surface. The rear optical distance measuring device 4 emits light to the road surface, receives the reflected light, and measures the rear height Bh between the vehicle 6 and the road surface.

As the distance measuring device, an ultrasonic distance measuring device can be used. That is, the ultrasonic ranging device emits ultrasonic waves to the road surface, receives reflected ultrasonic waves reflected from the road surface, and receives a front height Fh and a rear height B between the vehicle 6 and the road surface.
Measure h. Reference numeral 5 denotes an altitude calculation unit. In the altitude calculation unit 5, distance data Fh of the front height is input from the front optical distance measuring device 3 attached to the vehicle 6 at a distance, and distance data Bh of the rear height is output from the rear optical distance measuring device 4. The road surface inclination angle θ ₀ is obtained based on these inputs and the distance L between the two optical distance measuring devices measured in advance. By setting the position of the optical distance measuring device at the front and rear of the vehicle as in the embodiment, the distance L
And the relative δθ can be measured with high accuracy.

Road surface inclination angle θ ₀ = vehicle pitch θ−relative δθ = vehicle pitch angle θ−tan ⁻¹ ｛(front height Fh−rear height B
h) / “interval”｝ The altitude is calculated by the formula: altitude = Σ (distance change) ・ θ10 initial altitudes. Here, if the initial altitude is set to zero, the altitude can be obtained as a height difference. The distance change is a traveling distance per unit time, that is, a vehicle speed.

[0013]

As described above, according to the present invention, a distance measuring device for measuring the distance between a vehicle and a road surface is provided at a distance from each other in the longitudinal direction of the vehicle, and a difference between distance data obtained from the distance measuring device is determined. Measuring the relative angle between the front-rear direction of the vehicle and the road surface based on the vehicle, and correcting the vehicle pitch angle by the relative angle to calculate the altitude, thereby accelerating and decelerating the vehicle, loading,
Even if the longitudinal axis of the vehicle fluctuates due to the number of passengers, the amount of gasoline, and other conditions, this is corrected, and the altimeter for the vehicle that calculates the altitude with high accuracy can be configured. The installation position of the distance measuring device is set at the front part and the rear part of the vehicle as in the embodiment.
The relative δθ can be measured with high accuracy. In addition, by using an optical distance measuring device or an ultrasonic distance measuring device as the distance measuring device, a practical vehicle altimeter can be manufactured at relatively low cost.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an embodiment.

FIG. 2 is a block diagram illustrating a vehicle altimeter and a distance measuring device.

FIG. 3 is a block diagram illustrating a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vehicle speed sensor 2 Vehicle inclination angle calculation part 3 Distance measuring device 4 Distance measuring device 5 Altitude calculation part 6 Vehicle 10 Accelerometer

Claims (4)

[Claims] 1. A vehicle pitch angle is calculated based on an acceleration signal obtained from an accelerometer attached to a vehicle with an input shaft in the front-rear direction of the vehicle, and the vehicle pitch angle is multiplied by a travel distance to obtain an altitude of the vehicle. In a vehicle altimeter to measure, a distance measuring device for measuring the distance between the vehicle and the road surface is provided at a distance from each other in the front-rear direction of the vehicle, and based on a difference in distance data obtained from the distance measuring device, An altimeter for a vehicle, which measures a relative angle between road surfaces and calculates an altitude by correcting a vehicle pitch angle based on the relative angle. 2. The vehicle altimeter according to claim 1, wherein the distance measuring device is mounted on a front portion and a rear portion of the vehicle. 3. An altimeter for a vehicle according to claim 1, wherein the distance measuring device is an optical distance measuring device. 4. An altimeter for a vehicle according to claim 1, wherein the distance measuring device is an ultrasonic distance measuring device.