JPH08261761A - Method for canceling offset in measurement with gyro - Google Patents

Abstract

PURPOSE: To accurately cancel an offset by a method wherein measurement of an offset angle velocity is executed again when the angle velocity in the measuring of the offset angle velocity exceeds a predetermined value. CONSTITUTION: An amplitude detection circuit 6 detects a maximum amplitude value App in the variation of an angle velocity signal (wa) obtained during the measuring. A control circuit 7 inputs the maximum amplitude value App, and compares it with a predetermined threshold level S1. When the compared result is App >=S1, the measurement is repeated by controlling an integrating circuit 3 and the circuit 6 and when the result is App<S1, the measurement is stopped at that time. Before offset cancel is executed, an offset angle velocity signal (wo) is measured. At that time, an object 2 to be measured and a gyro 1 are stopped, the angle velocity signal (wa) that the gyro 1 outputs is integrated by the integrating circuit 3 and the maximum amplitude value App of the angle velocity signal (wa) is detected by the circuit 6. When a predetermined measuring time has passed, a primary measurement is completed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an offset canceling method for improving measurement accuracy in position measurement of a civil engineering machine or the like using a gyro.

[0002]

2. Description of the Related Art In a mobile civil engineering machine, particularly a tunnel excavating machine, it is necessary to measure its operating position with high accuracy, and recently, a measuring method using a gyro has been used. In this gyro measurement, the angle is detected by time-integrating the angular velocity signal obtained by the gyro, and the displacement is detected by integrating the angle signal with the distance detected by another rangefinder. It is possible to measure how much is displaced from the reference position in which angle direction.

In such gyro measurement, the following two major errors are generally known. The first is due to temperature changes in the use environment. That is, when the gyro is used in a temperature environment different from that at the time of manufacture, the parts are thermally deformed and the sensitivity to the angular velocity changes. The second is due to the rotation of the earth. That is, the gyro measures the absolute angular velocity in the inertial system, but the user usually wants the angular velocity relative to the earth. Therefore, the required angular velocity cannot be obtained without removing the rotation of the earth.
This error depends on the latitude of the earth used.

The above two errors are constant under the same environment of use and can be regarded as steady deviations. Focusing on this, an error removal method called offset cancellation has been conventionally used. A block diagram for realizing this is shown in FIG.

In FIG. 6, a gyro 1 is fixed on an object to be measured 2 such as a civil engineering machine. First, prior to execution of the position measurement of the object to be measured 2, the object to be measured 2 is made to stand still in the usage environment, and the angular velocity there is measured. Gyro 1
The angular velocity signal ωa obtained in step 1 is integrated by the integrating circuit 3 for a certain period of time, and this is divided by the measurement time to obtain the average angular velocity at rest. Since this should originally be zero, this average angular velocity is stored in the memory 4 as the offset angular velocity signal ωo.

The offset is canceled by subtracting the offset angular velocity component ωo stored in the memory 4 from the actual output angular velocity signal ωa of the gyro 1 obtained during the movement of the DUT 2 in the subtraction circuit 5. The final angular velocity signal ω is obtained.

[Problems to be Solved by the Invention]

In order to perform such offset cancellation, it is necessary to make the DUT 2 stationary at the time of measuring the offset angular velocity. However, for equipment used at outdoor construction sites, such as tunnel excavating machines,
Correct offset cancellation is difficult.

This is because when a vehicle or the like passes around, disturbance vibration occurs and the object moves during the measurement of the offset angular velocity. In this case, the gyro recognizes the angular velocity during that time as a value at rest, even though the object is moving.

In particular, in recent tunnel excavation, the non-excavation method has begun to spread, and it is necessary to measure the position underground on the road through which ordinary vehicles pass. In this case, even if all the construction machines are stopped, disturbance will occur. For the above reasons, there has been a demand for a method of accurately performing offset cancellation under the condition of disturbance.

A first object of the present invention is to make it possible to obtain an offset angular velocity at a timing that is not affected by a disturbance so that accurate offset cancellation can be performed.

A second object is to separate the disturbance from the electrical noise generated by the gyro so that the offset angular velocity can be obtained more accurately and the accurate offset cancellation can be performed.

[0012]

According to a first aspect of the invention for achieving the first object, an offset angular velocity is measured when a gyro is stopped, and the offset angular velocity is subtracted from a movement angular velocity measured thereafter, In the offset cancellation method for obtaining an angular velocity without error, when the change in the angular velocity during the measurement of the offset angular velocity is equal to or more than a preset value, the offset angular velocity is measured again, and the change in the angular velocity is less than the preset value. The angular velocity measured at this time is set to the osset angular velocity.

According to a second aspect of the present invention for achieving the second object, an offset angular velocity is measured when the gyro is stopped, and the offset angular velocity is subtracted from the movement angular velocity measured thereafter to obtain an angular velocity without error. In the offset canceling method, a means for measuring the acceleration of the gyro is provided, and when the measured acceleration is a preset value or more, the offset angular velocity is measured again, and when the acceleration is less than the preset value. The measurement angular velocity of is set to the osset angular velocity.

[0014]

In the first invention, if the object is stationary,
Since the offset angular velocity is stationary, its change should be small. Therefore, measure the change in angular velocity at rest,
When the change is larger than the threshold value, it is determined that there is a disturbance, and the measurement is performed again. When the change is smaller than the threshold value, it is determined that there is no disturbance, and the angular velocity measured at that time is captured as an offset angular velocity.

In the second aspect of the invention, the angular velocity signal output by the gyro is a signal obtained by superposing the noise of the electric circuit on the true angular velocity. Therefore, if the disturbance vibration is small,
It is difficult to determine whether the change in output value is due to disturbance or electrical noise. Therefore, in the second aspect of the invention, the acceleration of the gyro is detected by the accelerometer, and the angular velocity signal when the acceleration change is less than the threshold value is fetched as the offset angular velocity. Since the electrical noise of the accelerometer is much smaller than the electrical noise of the gyro, it is possible to obtain an offset angular velocity that eliminates even a minute disturbance similar to the electrical noise of the gyro.

[0016]

The present invention focuses on the fact that disturbances that occur in tunnel excavating machines and the like are irregular and intermittent, and automatically selects a time zone (timing) in which there is no disturbance and measures the offset angular velocity. is there. That is, the disturbance that cannot be removed conventionally is ground vibration due to a general vehicle passing through the surroundings, so if the offset angular velocity is measured with the timing of vehicle passage, etc., the correct offset angular velocity can be obtained. Offset cancellation using this can be correctly performed.

Examples of the present invention will be described below. FIG. 1 is a block diagram for implementing the offset cancellation of the first embodiment. The same components as those in FIG. 6 described above are designated by the same reference numerals. An amplitude detection circuit 6 detects a maximum amplitude value App (pp value) of a change in the angular velocity signal ωa obtained during the measurement period. Reference numeral 7 is a control circuit which inputs the maximum amplitude value App and compares it with a preset threshold value S1. If the comparison result is App ≧ S1, the integration circuit 3 and the amplitude detection circuit 6 are controlled to measure again. If App <S1, the measurement is stopped there.

The waveform of the angular velocity signal ωa output from the gyro 1 is shown in FIG. This angular velocity signal ωa is the offset angular velocity signal ωo due to the rotation and thermal deformation of the earth, and the gyro 1
Noise An of the internal circuit of the, fluctuation due to disturbance vibration As
Etc. are included.

In performing offset cancellation, the offset angular velocity signal ωo is first measured as in the conventional case. At this time, the DUT 2 is stopped and the gyro 1 is stopped, and the angular velocity signal ω output by the gyro 1 is output.
The integrating circuit 3 integrates a, and the amplitude detecting circuit 6 detects the maximum amplitude value App of the change in the angular velocity signal ωa. After a certain measurement time (several seconds to several minutes),
The first measurement N1 is completed.

The control circuit 7 determines whether or not the maximum amplitude value App during this measurement period is larger than a preset threshold value S1. Since this threshold value S1 is set to a value slightly larger than that due to the electrical noise An, the electrical noise An
Will never be detected.

In the first measurement N1 described above, as shown in FIG. 2, the disturbance vibration As enters within the measurement time, and the threshold S1
The value of the maximum amplitude App is larger than that. Therefore, the control circuit 7 issues a command to the integration circuit 3 and the amplitude detection circuit 6 to perform the measurement again, and performs the second measurement N2. Even in the second measurement N2, the amplitude value App detected by the amplitude detection circuit 6 is larger than the threshold value S1.

Therefore, the control circuit 7 issues a command to the integrating circuit 3 and the amplitude detecting circuit 6 to perform the measurement again. Less than,
Similarly, the measurement is repeated until the maximum amplitude App detected by the amplitude detection circuit 6 becomes smaller than the threshold value S1.

As described above, when the control circuit 7 determines that the maximum amplitude App of the angular velocity signal is smaller than the threshold value S1 in the Nth measurement Nn, the control circuit 7 issues a command to end the measurement for the first time. Give out. Next, this Nth measurement N
The integration result obtained in the integration circuit 3 by n is divided by the measurement time to obtain the average angular velocity, which is stored in the memory 4 as the offset angular velocity signal ω o. Further, the control circuit 7 informs the operator that the measurement of the offset angular velocity has been completed by a display or a speaker or the like (not shown).

Using the offset angular velocity signal ω o measured as described above, thereafter, the measurement of the actual motion angular velocity is started. As described above, the largest error part of the measured angular velocity of the gyro is the offset angular velocity due to thermal deformation and rotation of the earth. The object to be measured 2 is shown in FIG.
3 shows the measured angular velocity signal ωa during the motion of. Since the offset angular velocity signal ωo is stored in the memory 4, if the subtraction circuit 5 subtracts the offset angular velocity signal ωo from the measured angular velocity signal ωa, as shown in FIG. It becomes possible to obtain the angular velocity signal ω without.

FIG. 4 is a block diagram for implementing the offset cancellation of the second embodiment. The same components as those in FIG. 1 are designated by the same reference numerals. Here, an accelerometer 8 is fixedly installed in addition to the gyro 1 with respect to the DUT 2, and the output signal of the accelerometer 8 is detected by the amplitude detection circuit 9
Connected to the maximum amplitude Bpp detected by the amplitude detection circuit 9
Is compared with a preset threshold value S2 in the control circuit 10, and when the maximum amplitude Bpp is equal to or larger than the threshold value S2, the measurement command is issued again to the amplitude detection circuit 9 and the integration circuit 3.

When an offset cancel command is applied from the outside, the integrator circuit 3 integrates the angular velocity signal ωa output from the gyro 1 and the acceleration signal output from the accelerometer 8 while the DUT 2 is stationary. The maximum amplitude Bpp of the change in B is detected by the amplitude detection circuit 6.

FIG. 5A shows the waveform of the output acceleration signal B of the accelerometer 8, and FIG. 5B shows the waveform of the output angular velocity signal ωa of the gyro 1. Output acceleration signal B of accelerometer 8
Includes the vibration Bs due to the disturbance vibration and the electric noise Bn. Since the electric noise Bn of the accelerometer 8 is much smaller than the electric noise An of the gyro 1, the accelerometer 8
The component of the disturbance vibration Bs with respect to the electric noise Bn in the output acceleration signal B can be clearly distinguished. Therefore, the threshold value S2 of the control circuit 10 is set to a value slightly larger than the electrical noise Bn generated in the accelerometer 9.

From the above, when the maximum amplitude Bpp of the change of the acceleration signal B obtained by the accelerometer 8 is equal to or more than the threshold value S2 set in the control circuit 10, a command is issued to the integration circuit 3 and the amplitude detection circuit 9 to measure again. repeat. In the Nth measurement Nn, when the maximum amplitude Bpp of the change of the acceleration signal B obtained by the accelerometer 8 becomes smaller than the threshold value S2, the measurement is ended, and the integration result of the integrating circuit 3 at that time is measured in the measurement time. The average angular velocity obtained is stored in the memory 4 as an offset angular velocity signal ω o. Subsequent operations are the same as those in the first embodiment described above.

In the second embodiment, since the disturbance vibration during the measurement of the offset angular velocity is measured by the accelerometer 8, the disturbance vibration and the electric noise can be easily separated from each other.
Even a small disturbance can be detected with high sensitivity, and it is possible to avoid capturing the measured angular velocity at that timing as an offset angular velocity, so that the offset angular velocity can be accurately measured.

[0030]

As described above, according to the first aspect of the present invention, when the change in the angular velocity during the measurement of the offset angular velocity is equal to or more than the preset value, the offset angular velocity is measured again. It is possible to measure the offset angular velocity at the timing when is not added. Therefore, it is possible to obtain an accurate offset angular velocity that excludes the influence of disturbance, and to realize accurate offset cancellation, for an object to be measured to which disturbance is intermittently and irregularly applied, such as a civil engineering machine. Becomes

According to the second aspect of the invention, the offset angle is measured again when the acceleration applied to the object to be measured is equal to or greater than a preset value, so that a minute disturbance similar to the electrical noise generated from the inside of the gyro occurs. Also in this case, the offset angular velocity can be measured while avoiding this, and the disturbance can be removed more accurately than in the first invention.

[Brief description of drawings]

FIG. 1 is a block diagram for implementing an offset canceling method according to a first embodiment of the present invention.

FIG. 2 is a waveform diagram for explaining offset angular velocity measurement according to the first embodiment.

FIG. 3 is a waveform diagram of angular velocity signals before (a) and after (b) offset cancellation according to the first embodiment.

FIG. 4 is a block diagram for implementing the offset canceling method of the second embodiment.

FIG. 5 is a waveform diagram of an acceleration signal (a) and an angular velocity signal (b) of the second embodiment.

FIG. 6 is a block diagram for implementing a conventional offset canceling method.

[Explanation of symbols]

1: Gyro, 2: Object to be measured, 3: Integration circuit, 4: Memory, 5: Subtraction circuit, 6: Amplitude detection circuit, 7: Control circuit,
8: accelerometer, 9: amplitude detection circuit, 10: control circuit.

Claims (2)

[Claims] 1. An offset canceling method for measuring an offset angular velocity when a gyro is stopped and subtracting the offset angular velocity from a motion angular velocity measured after that to obtain an angular velocity without error. An offset canceling method, wherein the offset angular velocity is measured again when the change is equal to or more than a preset value, and the measured angular velocity when the change in the angular velocity is less than the preset value is set as the offset angular velocity. 2. An offset canceling method for measuring an offset angular velocity when a gyro is stopped and subtracting the offset angular velocity from a subsequently measured motion angular velocity to obtain an error-free angular velocity, the means for measuring the acceleration of the gyro. When the measured acceleration is equal to or greater than a preset value, the offset angular velocity is measured again, and the measured angular velocity when the acceleration is less than the preset value is set as an offset angular velocity. Offset cancellation method.