JPH07101175B2 - Vehicle angle change amount detection device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a device for detecting an angle change amount of a vehicle using a gyro sensor.

<< Prior Art >> As a conventional vehicle angular change amount detection device, for example, a device described in JP-A-58-31376 is known. In this example, angular velocity information output from a gyro sensor is used. The amount of change in the angle of the vehicle is detected by integrating and adding.

That is, when this is explained now with reference to FIGS. 3 to 10, for example, if there is an input of −100 ° / sec to 100 ° / sec as the angular velocity Ω, it is proportional to the angular velocity Ω as shown in FIG. The output voltage is -5V to 5V. So in this case,
The relationship between the input angular velocity Ω and the output voltage V can be expressed by the straight line K ₁ shown by V = kΩ (where k is a constant) (1).

By the way, in the case of a gyro sensor, due to factors such as the temperature change of the amplifier, there is actually no angle change amount
Even if it is 0, the voltage V ₁ may be output. Therefore, in this case, apparently, the angle Ω _{1 of} Ω ₁ = V ₁ / k (2) is added to the angular velocity Ω of the solid line, and the straight line K ₁ is offset to K ₂ (hereinafter, this phenomenon is referred to as drift).

On the other hand, as shown in FIG. 4, when this drift occurs with a constant magnitude Ωb with respect to time t, the shaded portion N ₁ shown in FIG. =
In spite of 0, as shown in FIG. 5, the angle change amount θ increases with the passage of time t on the straight line K ₃ shown by θ = Ωbt (3).

Further, as shown in FIG. 6, when the drift increases linearly with respect to the time t, the angle change amount θ (corresponding to the shaded portion N ₂ in FIG. 6) becomes a secondary value as shown in FIG. It increases functionally.

Therefore, in the past, if there is a drift that can be represented by the straight line K ₄ in FIG. 8, points A, B, C, D when the vehicle is stopped
Drift amount Ωa, Ωb, Ωc, Ωd at each point
Was measured, and the sensor output was corrected (offset) based on this drift amount.

Therefore, the corrected angular velocity Ω is A as shown in FIG.
At points B, C, D, Ω = 0 will be corrected.

<< Problems to be Solved by the Invention >> However, in the conventional device as described above, although drift correction is performed at each point A, B, C, and D when the vehicle is stopped, The detection error caused by the drift from the previous correction to the current correction is left as it is (corresponding to the shaded areas N _A , N _B , N _C , and N _D in FIG. 9), and the error in the detected angle change θ Has a problem that it increases with the passage of time as shown in FIG.

<Object of the Invention> In view of the above problems, the present invention calculates an error amount of an angle change from once drift correction to next drift correction, and calculates the error amount from the calculated angle at that time. It is an object of the present invention to provide a vehicle angle change amount detection device capable of accurately detecting the vehicle angle change amount by subtraction.

<< Means for Solving Problems >> In order to solve the above problems, the present invention is configured as shown in FIG. 1, and an angular velocity detecting means for detecting an angular velocity of a vehicle by a gyro sensor and a When the stop state of the vehicle is detected by the vehicle stop detecting means b for detecting and the vehicle stop detecting means b, drift amount detection for detecting the drift amount of the gyro sensor from the angular velocity detected by the angular velocity detecting means a at that time. Means c, an angular velocity correction means d for successively subtracting the drift amount at the previous stop detected by the drift amount detection means c from the angular velocity detected by the angular velocity detection means a while the vehicle is traveling, and the angular velocity correction means d. Angle change amount calculating means e for calculating the angle change amount of the vehicle by integrating the angular velocity corrected by Elapsed time calculation means f for calculating the elapsed time until the vehicle stops once, drift change amount calculation means g for calculating the difference between the drift amount at the previous vehicle stop and the drift amount at the current vehicle stop, and the elapsed time calculation Based on the elapsed time from the last stop to the current stop and the drift change amount calculated by the means f and the drift change amount calculating means g, the error amount of the angle change caused by the drift from the last stop to the current stop is calculated. An error amount calculating means h for calculating, an angle change amount correcting means i for correcting the current angle change amount calculated by the angle change amount calculating means e based on the error amount calculated by the error amount calculating means h, It is characterized by including.

<< Description of Embodiments >> Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 shows a basic configuration in the case where the present invention is applied to a vehicle traveling azimuth detecting apparatus. In this embodiment, an gyro sensor output is used to detect an angle change amount, and as will be described later. Is given an initial azimuth, and the absolute running azimuth of the vehicle is detected by this.

In the figure, a gyro sensor 1 is attached so as to detect the rotation around the yaw axis of the vehicle, and is configured to output a voltage proportional to the angular velocity of the yaw axis. The output voltage of the gyro sensor 1 is output to the CPU via the A / D converter 3.
The vehicle speed information output from the vehicle speed sensor 2 is input to the CPU 4 as well as being input to the CPU 4, and the CPU 4 is configured to perform various arithmetic processing based on the input information to detect the traveling direction of the vehicle. ing.

In the present embodiment, the gyro sensor 1 for detecting the rotation around the yaw axis is used as described above, but any other device such as a frame rotating gyro, an optical fiber gyro, a vibration gyro or the like capable of detecting the angular velocity may be used. Any of these can be used.

The procedure for detecting the traveling direction θ of the vehicle, which is executed by the CPU 4, will be described below with reference to the flowcharts of FIGS. 15 and 16.

FIG. 15 shows a processing procedure for detecting the traveling azimuth θ of the vehicle by sequentially integrating and adding the angular velocity information output from the gyro sensor 1, and the unit time (for example,
The above processing procedure is executed by the timer interrupt processing for each 1 msec) ΔT.

That is, first, the output voltage V of the gyro sensor 1 is A / D
Input to CPU 4 via converter 3 (step 10
0).

By the way, the angular velocity equivalent voltage input by the processing of step 100 includes a drift component. Therefore,
In the following step 110, the voltage V input as described above is multiplied by 1 / k to obtain the angular velocity V / k including the drift amount, and the drift amount is subtracted from this value.

As the drift amount used in this process, the latest drift amount detected at that time is used, as described later.

When the angular velocity Ω obtained by subtracting the constant drift amount is obtained in this way, the angle change amount Ω × ΔT between ΔT is added to the detection azimuth θ to successively update the detection azimuth θ (step 120).

Thus, in this embodiment, the azimuth θ is detected while subtracting the latest drift amount detected at that time from the output value of the gyro sensor 1 including the drift amount.

The above is the processing procedure of the traveling direction detection executed by the timer interruption for each ΔT.

Next, with reference to the flowchart of FIG. 16, a processing procedure of drift correction when the vehicle is stopped and a traveling direction correction using the drift correction, which is a characteristic part of the device of the present embodiment, will be described.

First, when the program starts, the initial azimuth θ and the amount of drift at that time are initialized (step 200).

Next, it is determined whether or not the vehicle is stopped based on the output of the vehicle speed sensor 2 (step 210). When the vehicle is stopped, the actual angular velocity Ω = 0 is obvious, so drift correction is performed (step 220). ). In this case, since the apparent angular velocity Ω at that time point is the drift amount, the value is calculated (step 220).

In this case, the angular velocity Ω is given by the following equation.

Ω = gyro sensor output voltage (V) / k (4) On the other hand, when the latest drift amount is calculated from the output voltage of the gyro sensor 1 while the vehicle is stopped, this data is used for the processing in step 110. After that, it is used for the correction of the output value of the gyro sensor 1 until a new drift amount is calculated.

On the other hand, when the drift amount is detected as described above, based on the drift change amount from the time when the drift correction was performed last time to the time when the drift correction was performed this time, and the elapsed time therebetween, the error in the direction detection caused by the drift. The amount θ _M is calculated (step 230).

That is, θ _M is Will be given as.

The amount of drift change = current drift amount-old drift amount elapsed time = current time-old time.

Now, this will be described with reference to FIG. 11. The straight line K ₅ shows the drift amount when there is no change in the angular velocity. In addition,
In this example, the drift amount increases in proportion to the time t as shown in FIG.

In this case, the shaded portion N corresponds to the error amount θ _M of the detected azimuth expressed by the equation (5).

Therefore, if the area is subtracted from the detected azimuth θ each time the drift correction is performed, the accumulation of the error amount θ _M can be prevented.

Therefore, in the subsequent step 240, the current drift amount and the current time are stored as the old drift amount and the old time, respectively, in preparation for the next correction process.

Then, the error amount θ calculated above from the current detected orientation θ
Subtract _M to perform the correction processing of the detected azimuth (step 250). Then, the processes of steps 210 to 250 are repeated thereafter.

FIG. 12 is an explanatory diagram in the case where the detected azimuth θ is corrected by the above correction process, but the detected azimuth θ (in this case, of the angular velocity, which increases while drawing a quadratic curve from the old time to the current time tn Since there is no change, the error amount θ _M = θ) is corrected to θ = 0 at the current time tn.

Figure 13 shows the amount of drift when there is a change in the angular velocity of the vehicle.
The detected angular velocity Ω affected by K ₆ is shown. As shown in the figure, the drift amount K ₆ gradually increases while the vehicle is traveling. Therefore, the detected angular velocity Ω also includes the drift amount K ₆ .

By the way, in this case, in this embodiment, the drift correction is performed at the old time to and the current time tn, and the error amount of the detected bearing during that time is detected (corresponding to the shaded portions No, N _N in FIG. 13). Subtract from θ.

FIG. 14 schematically shows the result of the above-mentioned correction process, where L ₁ is the true direction, L ₂ is the detection direction based on the raw gyro sensor output value when not corrected, and L ₃ is the actual direction. 6 illustrates a detection azimuth when corrected by the apparatus according to the embodiment. As is also clear from the figure, it can be seen that the corrected azimuth L ₃ is corrected in a manner very similar to the true azimuth L ₁ at every drift-corrected to, tn times.

In this embodiment, the error amount θ _M is calculated on the assumption that the drift amount is changing temporarily, but the calculation method of θ _M should be changed according to the drift characteristic of the gyro sensor used. You can

That is, referring again to FIGS. 4 to 7,
In this embodiment, since it is assumed that the drift amount changes temporarily, as shown in FIG.
When there is a drift of, the time t and the angular velocity Ω are expressed by the following equations.

Ω = Ωb / tbt (6) Therefore, the error amount θ _M at tb is Can be expressed (see FIG. 7).

On the other hand, for example, as shown in FIG.
If it is better to approximate as, the error amount θ _M at tb can be expressed as θ _M = ∫Ωdt = Ωb · t = Ωbtb (8) (see FIG. 5).

Therefore, the method of calculating the error amount θ _M may be changed appropriately depending on the drift characteristics of the gyro sensor used.

In this embodiment, the azimuth θ is detected by detecting the angular velocity Ω about the yaw axis of the vehicle.
The azimuth θ can also be detected by detecting the angular velocity around the roll axis.
Can be detected.

As described above, when the vehicle stop drift correction is performed as described above, the device of the present embodiment, based on the amount of drift change from the time of the previous correction and the elapsed time between them, determines the error amount of the detected azimuth during that time. The detected direction is corrected by calculating and subtracting this error amount from the detected direction at that time.

Therefore, even if the azimuth detection is continued based on the angular velocity information output from the gyro sensor for a long period of time, it is possible to prevent the error from accumulating and the azimuth can be detected accurately.

Further, although the apparatus of this embodiment is used in a navigation system or the like for calculating the current position by integral navigation, it is possible to accurately detect the azimuth, and therefore it is possible to accurately calculate the current position.

In the present embodiment, the initial azimuth θ is set by the initial processing, the angular velocity information obtained sequentially is integrated and added to this initial azimuth θ, and the traveling azimuth θ as the absolute azimuth is thereby obtained.
However, if it is sufficient to measure the relative direction change amount of the vehicle, the above-described initial processing is not necessary.

For example, the applicant has previously filed Japanese Patent Application No. 63-47189,
The traveling direction is detected by combining a gyro sensor that can accurately detect the relative direction change amount without being affected by the surrounding magnetic field environment and a geomagnetic direction sensor that can detect the absolute direction while being affected by the surrounding magnetic field environment. However, in this case, since the gyro sensor only needs to be able to accurately detect the relative azimuth change amount, the above-described initial processing is not necessary. When the device according to the present embodiment is mounted on this kind of azimuth meter, the traveling azimuth can be detected more accurately.

<< Effects of the Invention >> The vehicle angle change amount detection device according to the present invention, when a new drift amount is detected as described above, based on the drift change amount from the previous detection time and the elapsed time from the previous detection time, Since the error amount of the angle change due to the drift from the previous detection is calculated, and the current angle change amount is corrected based on this error amount, it is possible to correct the drift from once to the next drift correction. The effect of the drift can be completely eliminated, and the angle change amount of the vehicle can be accurately detected.

[Brief description of drawings]

FIG. 1 is a diagram corresponding to claims of the present invention, FIG. 2 is a block diagram showing a basic configuration of the present invention, FIG. 3 is an explanatory diagram of drift characteristics, and FIG. 4 is an explanatory diagram of drift characteristics when a drift amount is constant, FIG. 5 is an explanatory diagram of the azimuth error amount when there is a drift characteristic shown in FIG. 4, FIG. 6 is an explanatory diagram of the drift characteristic when the drift amount increases in proportion to time, and FIG. FIG. 8 and FIG. 9 are explanatory views of drift correction in the conventional example, FIG. 10 is an explanatory diagram of the azimuth error amount in the conventional example, and FIGS. 11 to 13 are Explanatory view of the drift correction operation in the present embodiment,
FIG. 14 is a schematic diagram when the traveling azimuth is corrected by the present embodiment, and FIGS. 15 and 16 are flowcharts showing the processing procedure of the present embodiment. 1 …… Gyro sensor 2 …… Vehicle speed sensor 3 …… A / D converter 4 …… CPU

Claims (1)

[Claims] 1. An angular velocity detecting means for detecting an angular velocity of a vehicle by a gyro sensor, a vehicle stop detecting means for detecting a stop state of the vehicle, and a stop state of the vehicle detected by the vehicle stop detecting means A drift amount detecting means for detecting a drift amount of the gyro sensor from the angular velocity detected by the angular velocity detecting means, and a previous stop detected by the drift amount detecting means from the angular velocity detected by the angular velocity detecting means while the vehicle is traveling. The angular velocity correction means for successively subtracting the drift amount of the vehicle, the angular change amount calculation means for calculating the angular change amount of the vehicle by integrating the angular velocity corrected by the angular velocity correction means, and the previous vehicle stop time to the current vehicle stop time. Elapsed time calculation means to calculate the elapsed time up to, the amount of drift when the previous vehicle was stopped and the current vehicle stopped Based on the drift change amount calculation means for calculating the difference in drift amount and the drift change amount and the elapsed time from the previous stop time to the current stop time calculated by the above elapsed time calculation means and drift change amount calculation means Error amount calculation means for calculating the error amount of the angle change due to the drift from the current time to the current stop, and the current angle calculated by the angle change amount calculation means based on the error amount calculated by the error amount calculation means. An angle change amount detection device for a vehicle, comprising: an angle change amount correction means for correcting the change amount.