JPH0443213B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a centrifugal force insensitive inclinometer that does not produce errors due to centrifugal force when a vehicle turns.

[Prior art]

Traditionally, inclinometers have been used for purposes such as detecting the amount of inclination relative to the horizontal state and issuing warnings of vehicle overturning. It was used to detect the amount of inclination.

However, such conventional inclinometers have the disadvantage that centrifugal force when the vehicle turns also acts on the weight, which causes an error in the indicated value.

[Object and structure of the invention]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a centrifugal force insensitive inclinometer that does not produce errors when centrifugal force is generated in a vehicle.

In order to achieve this purpose, this invention
From the differential gear wheel shaft of the differential gear,
The rotational speed of each of the left and right wheels is detected, the centrifugal force is determined from this rotational speed, and the centrifugal force is corrected for the apparent amount of inclination to determine the correct amount of inclination.

〔Example〕

Before entering into the description of the embodiments, the principle of the present invention will be explained with reference to an example during cornering shown in FIGS. 1 and 2. Each specification in the figure is defined as follows.

L ₁ : Travel distance of the inner wheels per unit time L ₂ : Travel distance of the outer wheels per unit time θ ₂ : Rotation angle of the vehicle per unit time R: Cornering radius l: Vehicle width V ₁ : Inner wheel speed V ₂ : Outer wheels Speed V: Vehicle speed L: Center travel distance (inclination sensor setting point) α: Centrifugal force applied to the vehicle N ₁ : Number of pulses generated per unit time from the rotation sensor that detects the rotation speed of the inner ring N ₂ : Number of pulses generated per unit time of the outer ring The number of pulses generated per unit time by the rotation sensor that detects the rotation speed. Since the traveling distance is the integral value of the pulses generated by the rotation sensor, and the speed is the differential value of the pulses, it can be expressed as follows.

L ₁ =∫N ₁ dt …(1) L ₂ =∫N ₂ dt …(2) V ₁ =dN ₁ /dt …(3) V ₂ =dN ₂ /dt …(4) Both speed and distance traveled are units Since it comes down to counting the number of pulses per time, the following relationship holds true.

∫N ₁ dt∝dN ₁ /dt∝F(N ₁ ) ...(5) ∫N ₂ dt∝dN ₂ /dt∝F(N ₂ ) ...(6) From the arc theorem, the following equation holds true.

R・θ ₂ =L=L ₁ +L ₂ /2 =F(N ₁ )+F(N ₂ )/2 …(7) l・θ ₂ ≒L ₂ −L ₁ =F(N ₂ )−F(N ₁ ) …(8) R=F(N ₁ )+F(N ₂ )/2・θ ₂ …(9) θ ₂ =F(N ₂ )−F(N ₁ )/l …(10) Therefore, the following The formula holds true.

R=l{F(N ₁ )+F(N ₂ )}/2{F(N ₂ )−F(N ₁
)}…(11) On the other hand, centrifugal force is expressed as follows.

α=V ² /R=(V ₁ +V ₂ /2) ²・1/R={F(N ₁ )+
F(N ₂ )} ² /4R = {F(N ₂ )−F(N ₁ )} {F(N ₁ )+F(N ₂ )} ²
/2l {F(N ₁ )+F(N ₂ )} = {F(N ₂ )−F(N ₁ )}−{F(N ₁ )+F(N ₂ )}
/2l...(12) Equation (12) shows that the centrifugal force α is expressed as a function of the number of pulses generated from the rotation sensor.

Next, an analysis of the inclination angle element when tilting to the right will be performed based on FIG. However, the conditions shall be set as follows.

a The inclination sensor is parallel to the road surface and detects the acceleration of the vehicle in the left and right directions.

b The tilt sensor outputs a negative signal when tilting to the right,
It is assumed that a positive signal is output when tilting to the left.

c The direction of centrifugal force is determined from the speed ratio of the two pairs of speed sensors, and is positive when tilting to the right and negative when tilting to the left.

d Since the direction of motion is always constant, it is assumed to be positive polarity.

e If the final tilt angle calculation result is positive, tilt to the right;
When it is negative, it is tilted to the left.

Now, as shown in FIG. 3, when a vehicle is running on a right inclined surface with an angle θ with a centrifugal force of α, the inclination sensor receives a centrifugal force of (αcosθ−gsinθ). At this time, if the centrifugal force component α cos θ is larger than the gravitational acceleration component force, even if the road surface slopes to the right, the inclination sensor will detect the angle θ ₁
Outputs a left tilt signal with a value corresponding to . This value has a positive polarity due to the conditions, and since the road surface slopes to the right, the centrifugal force also has a positive polarity, so the output signal from the inclination sensor is as follows.

F(θ ₁ )=K(αcosθ−gsinθ) (13) Equation (14) is obtained from vector balance.

tanδ=α/g…(14) As a result, the following formula is obtained.

δ=tan ^-1 (α/g) …(15) α=√ ² + ² sin δ…(18) g=√ ² + ² cos δ…(19) As a result, the following formula is obtained.

Since all the variables in equation (21) are known values, the correct value of the inclination angle θ can be calculated based on the signal representing the apparent inclination. Furthermore, as is clear from Fig. 3, the direction of the gravitational acceleration g and the perpendicular direction of the tilt sensor are constant, and since the output of the tilt sensor also has polarity, when the output of the tilt sensor is positive, δ =θ ₁ +θ holds true, and δ>θ ₁ is always satisfied. Therefore, in equation (21), the first term is always larger, θ is a positive value, and the calculation result is tilted to the right.

Next, an example will be described in which the vehicle travels on a right inclined surface with an inclination angle θ with a centrifugal force of α, and the gravitational acceleration component is larger than the centrifugal force component as shown in FIG. At this time, the tilt sensor tilts to the right, so its output signal has negative polarity, and the following equation holds true.

Since equation (21) was positive, equation (22) naturally has a positive value, indicating a rightward slope.

The above is the analysis for the right tilt, but next, when the centrifugal force component exceeds the gravitational acceleration component force in the left tilt, the balance of forces will be as shown in Figure 5, so the centrifugal The force is of negative polarity and the tilt is to the left, but the tilt sensor outputs a signal for right tilt, so its output F
(θ1) has negative polarity. Therefore, the following formula holds true.

As a result, the calculation result has negative polarity, indicating a leftward slope.

Similarly, when the vehicle is traveling on a left inclined surface and the gravitational acceleration component force exceeds the centrifugal acceleration component force, the following will occur.

Since equation (23) always takes a negative value, equation (24) also takes a negative value, and the calculation result represents a left slope.

Furthermore, when no centrifugal force is applied, the speed ratio from the two speed sensors is 1, and the centrifugal force α is zero. In this case, since there is no centrifugal force component, the output signal of the tilt sensor corresponds to the tilt angle θ.

As described above, the correct inclination angle θ can be calculated from known data in any case.

FIG. 6 is a block diagram showing one embodiment of the present invention. In the same figure, 1a is the rotation speed of the left wheel axle
_1b is a rotation sensor that detects the rotation speed N ₂ of the right wheel axle; 2 is an inclination sensor that detects the apparent inclination θ of the vehicle; 3a, 3b
4 is an amplification unit, 4 is a calculation unit that calculates acceleration, 5 is a calculation unit that calculates the true amount of inclination, 6 is an A/D converter, 7 is a D/A converter, 8 is a driver, 9 is a display, and 10 is a constant The setting section 11 is a power supply section. Of these, the arithmetic unit 4 performs the calculation of equation (24), and the calculation unit 5 performs the calculations of equations (21), (22), (23), and (24).

The operation of the device configured in this way is as follows. As the vehicle travels, rotation sensors 1a, 1
Signals N1 and N2 representing the rotational speed of the left and right wheel axles are generated from b, respectively, and these signals are supplied to the calculation section 4 via the amplification section 3a. Calculate the centrifugal force α based on the constant signal supplied from the section 10,
The calculation result is supplied to the calculation section 5.

On the other hand, the signal F (θ ₁ ) representing the apparent tilt angle detected by the tilt sensor 2 is transmitted to the amplifying section 3b and the A/
The signal is supplied to the calculation section 5 via the D converter 6. As a result, the arithmetic unit 5 performs the aforementioned arithmetic operation based on the signals from the arithmetic unit 4, the A/D converter 6, and the constant setting unit 10, and generates a signal representing the true angle of inclination. This signal is converted into an analog signal by a D/A converter 7, and is supplied to a display 9 via a driver 8 for display.

[Effect of the invention] As explained above, the inclinometer according to the present invention has the following advantages:
Since the acceleration component has been removed from the apparent amount of inclination,
This has the effect that no error occurs in the indicated value when acceleration of the vehicle occurs.

[Brief explanation of the drawing]

1, 2 to 5 are diagrams for explaining the operation of the vehicle during cornering, and FIG. 6 is a block diagram showing one embodiment of the present invention. 1a, 1b... Rotation sensor, 2... Tilt sensor, 4, 5... Arithmetic unit.

Claims (1)

[Scope of Claims] 1. A vehicle speed sensor that detects the vehicle speed of a vehicle, an inclination sensor mounted on the vehicle that detects the inclination of a road surface, and first and second rotation sensors that detect the respective rotational speeds of both left and right wheels. , a centrifugal force calculation unit that calculates centrifugal force from the cornering radius of the vehicle calculated from the data of the first and second rotation sensors and the vehicle speed data calculated from the vehicle speed sensor; A centrifugal force insensitive inclinometer comprising: a tilt amount calculation unit that corrects the tilt amount obtained from the tilt sensor based on force to obtain a true tilt amount.