Inertial device

Abstract

To output gyro data satisfying a detection range and accuracy according to a change in a state of an airframe device.SOLUTION: The inertial device 100 includes a first inertial measurement unit 110 that generates first gyro data, a second inertial measurement unit 120 that generates second gyro data by a method different from that of the first inertial measurement unit, and an arithmetic unit 101 that compares the first gyro data and the second gyro data or refers to data other than the first gyro data and the second gyro data, selects one of the first gyro data and the second gyro data as selected gyro data, and supplies the selected gyro data to the body device 1.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an inertial device that generates gyro data used for navigation of an airframe, and more particularly to an inertial device that selects and outputs gyro data from a plurality of gyroscopes of different types. [Background technology]

[0002] In an inertial device used for inertial navigation of an aircraft device, there is a technology that mounts multiple gyroscopes of the same type and uses them as a redundant system in case of failure. There is also a technology that mounts multiple gyroscopes of the same type in an inertial device and improves accuracy by averaging or calculating errors. This type of inertial device technology is disclosed in Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Unexamined Japanese Patent Publication No. 2002-90174 Summary of the Invention [Problem to be solved by the invention]

[0004] There are several different types of gyroscopes that can be installed in inertial devices. Each type of gyroscope has different operating principles and characteristics (detection range, accuracy). That is, there are gyroscopes that can obtain high-accuracy data in a medium detection range, and gyroscopes that have a wide detection range but medium to low accuracy.

[0005] For example, if the aircraft is an unmanned underwater vehicle (UUV), the attitude changes significantly during launch and water entry, but the attitude changes less during underwater navigation. Therefore, to respond to changes in the aircraft's situation, such as during launch, water entry, and underwater navigation, a medium- to low-precision gyroscope capable of handling a wide detection range must be employed. Similar problems can occur when the aircraft is another moving object, such as an aircraft or a flying object.

[0006] For this reason, it has been desired to realize an inertial device that can output gyro data that satisfies the detection range and accuracy requirements regardless of fluctuations in the detection range that accompany changes in the state of the aircraft device. SUMMARY OF THE INVENTION In order to solve the above problems, an object of the present invention is to provide an inertial device that can output gyro data that satisfies detection range and accuracy requirements in response to changes in the situation of the aircraft device. [Means for solving the problem]

[0007] (1) The inertial device of the present invention is an inertial device that generates gyro data used for navigation of an aircraft device, and includes a first inertial unit that generates first gyro data, a second inertial unit that generates second gyro data by a method different from that of the first inertial unit, and a calculation unit that compares the first gyro data with the second gyro data or refers to data other than the first gyro data and the second gyro data, selects one of the first gyro data and the second gyro data as selected gyro data, and supplies the selected gyro data to the aircraft device.

[0008] (2) In the inertial device of the present invention, in the above (1), a first gyroscope is mounted on the first inertial unit, and a second gyroscope is mounted on the second inertial unit, and the first gyroscope has higher accuracy than the second gyroscope, and the second gyroscope has a wider detection range than the first gyroscope.

[0009] (3) In the inertial device of the present invention, in the above (1), the first inertial unit is equipped with a dynamically tuned gyroscope, the second inertial unit is equipped with an optical fiber gyroscope, and the calculation unit selects the second gyro data from the time the aircraft device is launched to the time it enters water, and selects the first gyro data when the aircraft device is traveling underwater.

[0010] (4) In the inertial device of this invention, in the above (3), the calculation unit has a timer function that measures the elapsed time from the time of launch, and determines that the device is currently underwater navigating when the elapsed time exceeds a predetermined value.

[0011] (5) In the inertial device of this invention, in the above (3), the calculation unit determines the behavior of the aircraft device by analyzing the first gyro data and the second gyro data, and determines whether the aircraft device is entering water or traveling underwater based on the behavior.

[0012] (6) In the inertial device of the present invention, in the above (1), the first inertial unit includes an optical fiber gyroscope, and the second inertial unit includes a Coriolis vibration gyroscope, and the calculation unit switches the selection from the first gyro data to the second gyro data when the first gyro data exceeds a predetermined threshold while the first gyro data is selected.

[0013] (7) In the inertial device of the present invention, in the above (6), the calculation unit switches the selection from the second gyro data to the first gyro data when the first gyro data falls below a predetermined threshold while the second gyro data is selected.

[0014] (8) In the inertial device of the present invention, in the above (1), the first inertial unit is equipped with an optical fiber gyroscope, and the second inertial unit is equipped with a Coriolis vibration gyroscope, and the calculation unit switches the selection from the first gyro data to the second gyro data if the first gyro data becomes an incorrect value due to an external factor while the first gyro data is being selected.

[0015] (9) In the inertial device according to the present invention, as described above in (8), the calculation unit compares the first gyro data with the second gyro data and, if a difference of a certain value or more occurs, determines that the first gyro data is an incorrect value.

[0016] (10) In the inertial device of the present invention, in the above (8), a sensor for measuring the external environment of the aircraft device is further provided, and the calculation unit switches the selection from the first gyro data to the second gyro data if, while the first gyro data is selected, the external environment measured by the sensor has the possibility of causing an error in the first gyro data.

[0017] (11) In the inertial device of the present invention, in the above (8) or (9), when the calculation unit switches the selection from the first gyro data to the second gyro data and the erroneous value is eliminated, the calculation unit switches the selection from the second gyro data to the first gyro data.

[0018] (12) In the inertial device of the present invention, in the above (10), when the calculation unit switches the selection from the first gyro data to the second gyro data and the external environment that may cause an error in the first gyro data is eliminated, the calculation unit switches the selection from the second gyro data to the first gyro data. [Effects of the Invention]

[0019] According to this invention, an inertial device is provided which is equipped with a first inertial unit which generates first gyro data and a second inertial unit which generates second gyro data by a method different from that of the first inertial unit, and which compares the first gyro data with the second gyro data or refers to data other than the first gyro data and the second gyro data and selects either the first gyro data or the second gyro data as the selected gyro data, thereby making it possible to provide an inertial device which can output gyro data that satisfies the detection range and accuracy in accordance with changes in the situation of the aircraft device. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a configuration diagram showing the configuration of an inertial device according to a first embodiment. [Figure 2] 3 is a characteristic diagram showing the characteristics of various gyroscopes used in the inertial device of the first embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0021] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an inertial device according to the present invention will now be described with reference to the accompanying drawings. Embodiment 1 First, the inertial device according to the first embodiment will be described with reference to Fig. 1 and Fig. 2. Fig. 1 is a configuration diagram showing the configuration of the inertial device 100 according to the first embodiment. Fig. 2 is a characteristics diagram showing the characteristics of various gyroscopes used in the inertial device 100 according to the first embodiment.

[0022] [Configuration of the inertial device 100] The inertial device 100 generates gyro data used for inertial navigation of the airframe device 1. The airframe device 1 corresponds to various moving bodies such as an underwater vehicle, an aircraft, a flying object, an artificial satellite, or a spacecraft. The inertial device 100 mainly includes a calculation unit 101 , a first inertial unit 110 , and a second inertial unit 120 .

[0023] The first inertial unit 110 is equipped with a first gyroscope 110g and generates first gyro data. The second inertial unit 120 is equipped with a second gyroscope 120g that is different in type from the first inertial unit 110 and generates second gyro data. Note that illustrations and descriptions of known configurations such as gyro signal processing circuits provided in the first inertial unit 110 and the second inertial unit 120 are omitted.

[0024] The calculation unit 101 is provided with a determination unit 102 and a selection unit 103. The determination unit 102 makes a determination by comparing or analyzing the first gyro data sent from the first inertial unit 110 and the second gyro data sent from the second inertial unit 120. The determination unit 102 supplies the determination result to the selection unit 103. The selection unit 103 selects either the first gyro data or the second gyro data as selected gyro data based on the determination result of the determination unit 102. The calculation unit 101 supplies the selected gyro data to the aircraft device 1.

[0025] [Basic operation of the inertial device 100] The basic operation of the inertial device 100 is as follows. The first inertial unit 110 generates first gyro data using a first gyroscope 110g, and the second inertial unit 120 generates second gyro data using a second gyroscope 120g that is different in type from the first gyroscope 110g. The first gyroscope 110g is configured to have higher accuracy than the second gyroscope 120g, and the second gyroscope 120g is configured to support a wider detection range than the first gyroscope 110g. The calculation unit 101 compares the first gyro data and the second gyro data and selects either one that is appropriate at that time as the selected gyro data. For example, the calculation unit 101 selects the first gyro data, which has high accuracy, in a narrow detection range, and selects the second gyro data in a detection range that cannot be covered by the first gyro data. This allows gyro data that satisfies the detection range and accuracy requirements to be selected in response to changes in the situation of the aircraft device 1 and supplied to the aircraft device 1, thereby making it possible to satisfy both the accuracy and the detection range requirements.

[0026] Below, the basic operation of the inertial device 100 will be described for basic examples (1) to (3). In the following description, high / low accuracy, wide / narrow detection range, and high / low price are relative indicators between the first gyroscope 110g and the second gyroscope 120g. Basic example (1) The first gyroscope 110g mounted on the first inertial unit 110 has a narrower detection range but higher accuracy than the second gyroscope 120g, and the second gyroscope 120g mounted on the second inertial unit 120 has lower accuracy but a wider detection range than the first gyroscope 110g. In the calculation unit 101, if the determination unit 102 determines that there is a large change in the attitude or movement (hereinafter referred to as "behavior") of the aircraft device 1, the selection unit 103 selects the second gyro data from the second inertial unit 120 and supplies it to the aircraft device 1. In the calculation unit 101, if the determination unit 102 determines that there is a small change in the behavior of the aircraft device 1, the selection unit 103 selects the first gyro data from the first inertial unit 110 and supplies it to the aircraft device 1. Note that if there is a relatively large change in behavior when the aircraft device 1 starts operating and the change in behavior becomes small after a certain time has passed, the calculation unit 101 may use a timer function to switch the selection of the selection unit 103. This allows the inertial device 100 to supply the airframe device 1 with gyro data that satisfies the detection range and accuracy requirements according to the magnitude of the change in behavior of the airframe device 1, thereby satisfying both the accuracy and the detection range.

[0027] Basic example (2) The first gyroscope 110g mounted on the first inertial unit 110 has a narrower detection range but higher accuracy than the second gyroscope 120g, and the second gyroscope 120g mounted on the second inertial unit 120 has lower accuracy but a wider detection range than the first gyroscope 110g. In the calculation unit 101, if the determination unit 102 determines that the first gyro data exceeds a threshold while the selection unit 103 is selecting the first gyro data, the selection unit 103 switches the selection from the first gyro data to the second gyro data. Here, the threshold is determined based on a value before the first gyro data becomes saturated according to the maximum detection range of the first gyroscope 110g. This allows the inertial device 100 to supply gyro data that satisfies the detection range and accuracy requirements to the aircraft device 1 without interruption in accordance with changes in the behavior of the aircraft device 1, thereby satisfying both accuracy and detection range. In the calculation unit 101, if the judgment unit 102 judges that the first gyro data has fallen below a threshold while the selection unit 103 is selecting the second gyro data, the selection unit 103 can switch the selection from the second gyro data to the first gyro data.

[0028] Basic example (3) The first gyroscope 110g mounted on the first inertial unit 110 has higher accuracy than the second gyroscope 120g, but is susceptible to malfunction due to the influence of the external environment. The second gyroscope 120g mounted on the second inertial unit 120 has lower accuracy than the first gyroscope 110g. Furthermore, the second gyroscope 120g has a different detection principle from the first gyroscope 110g, and is less susceptible to the influence of the external environment under the same external environmental conditions as the first gyroscope 110g. In the calculation unit 101, if the determination unit 102 determines that the first gyro data has become an incorrect value while the selection unit 103 is selecting the first gyro data, the selection unit 103 switches the selection from the first gyro data to the second gyro data. This allows the inertial device 100 to supply the aircraft device 1 with gyro data that satisfies the detection range and accuracy requirements in accordance with changes in the environment outside the aircraft device 1, thereby satisfying both accuracy and stability. In the calculation unit 101, if the judgment unit 102 judges that the value of the first gyro data has become normal while the selection unit 103 is selecting the second gyro data, the selection unit 103 can switch the selection from the second gyro data to the first gyro data.

[0029] [Example of a gyroscope] Specific examples of gyroscopes that can be installed as the first gyroscope 110g of the first inertial unit 110 and the second gyroscope 120g of the second inertial unit 120 in the inertial device 100 of the first embodiment will be described below with reference to Fig. 2. In the following description, high / medium / low accuracy, wide / medium / narrow detection range, and high / medium price are relative indicators.

[0030] Interferometric Fiber Optic Gyroscope (i-FOG): An optical fiber coil is arranged in a ring shape, and the phase difference between clockwise and counterclockwise laser beams caused by the Sagnac effect is controlled to 0 by a phase modulator called an IOC, and angular velocity is measured based on the amount of control. It has high accuracy and a medium detection range (see i-FOG in Figure 2). It is expensive. There is a trade-off between accuracy and detection range.

[0031] Intensity detection type fiber optic gyroscope (Op Fiber Optic Gyroscope: abbreviated as "Op-FOG"): Optical fibers are arranged in a ring shape, and the phase difference between clockwise and counterclockwise laser beams caused by the Sagnac effect is detected as the intensity of the interference light to measure angular velocity. It has medium accuracy and a medium detection range (see Op-FOG in Figure 2). It is relatively small and moderately priced. There is a trade-off between accuracy and detection range.

[0032] Coriolis vibration gyroscope using MEMS (Micro Electro Mechanical Systems) technology (abbreviated as "MEMS"): By applying angular velocity to a vibrator made of piezoelectric elements using MEMS technology, different vibration modes resulting from the Coriolis force are generated, and angular velocity is measured by detecting these vibration modes. It is small, lightweight, and inexpensive. Depending on the design, it is possible to have a wide detection range exceeding 1000° / s. However, it tends to have lower accuracy compared to gyroscopes based on other principles (see MEMS in Figure 2).

[0033] Dynamically Tuned Gyro (DTG): The rotor, which acts as a top or flywheel, is rotated at the resonant frequency of the spring supporting the rotor, thereby reducing the rotor's support force. When angular velocity is applied in this state, the rotor tries to stay in place, causing it to shift position within the housing. This shift is controlled by the magnetic force of a torquer coil, returning it to its original position. Angular velocity is measured by detecting the current (proportional to angular velocity) flowing through the torquer coil. It has medium to high accuracy, and due to the presence of moving parts, it has a short lifespan and a narrow detection range (see DTG in Figure 2).

[0034] Ring Laser Gyroscope (RLG): A laser medium such as a mixture of helium and neon gas is sealed inside a triangular or square ring-shaped glass tube, and clockwise and counterclockwise laser light is oscillated and propagated. The phase difference between the clockwise and counterclockwise laser light caused by the Sagnac effect is detected as an interference fringe pulse to measure angular velocity. It has high accuracy and a medium detection range (see RLG in Figure 2). It is very expensive. It has a dead zone called lock-in near the zero point. It should be noted that the ring laser gyroscope is not used in the first inertial unit 110 and the second inertial unit 120 of the inertial device 100 of the first embodiment, but is shown for reference.

[0035] [Combination of Gyroscopes and Operation of Inertial Device 100] In the inertial device 100 of the first embodiment, a specific example of the aircraft device 1, and a specific example of the first gyroscope 110g and the second gyroscope 120g will be described below.

[0036] Example (1): The vehicle device 1 is a vehicle, such as an unmanned underwater vehicle, that is launched from a mother ship toward the water surface and travels underwater after entering the water. The first inertial unit 110 includes a first gyroscope 110g, which is a dynamic tuning gyroscope with a relatively narrow detection range but medium to high accuracy. The smaller the detection range of a dynamic tuning gyroscope, the higher the accuracy of the gyroscope. For this reason, the first inertial unit 110 is suitable for timing when there is little change in the behavior of the aircraft device 1 while it is traveling underwater. The second inertial unit 120 includes a second gyroscope 120g, which is a medium-precision fiber optic gyroscope with a medium detection range, specifically an intensity-detecting fiber optic gyroscope. The second gyroscope 120g has a slightly wider detection range than the first gyroscope 110g. Therefore, the second gyroscope 120g is suitable for the timing when the behavior of the aircraft 1 changes significantly from launch to immersion in water.

[0037] When the aircraft unit 1 is loaded into the launch device of the mother ship, the inertial unit 100 receives power supply from the aircraft unit 1. As a result, both the first inertial unit 110 and the second inertial unit 120 start operating. In the calculation unit 101, the determination unit 102 and the selection unit 103 perform the determination and selection as follows. The determination unit 102 determines that the aircraft body 1 is in a state ready for launch when power is supplied, and transmits the determination result to the selection unit 103. The selection unit 103 receives the determination result from the determination unit 102 and selects the second gyro data from the second gyroscope 120g in preparation for the launch of the aircraft body 1. When the judgment unit 102 analyzes the first gyro data and the second gyro data and detects the ejection of the aircraft device 1, it uses a timer function to communicate to the selection unit 103 the judgment result as to whether a predetermined period of time has elapsed since the ejection of the aircraft device 1. The selection unit 103 receives the determination result from the determination unit 102 and continues to select the second gyro data from the second gyroscope 120g until a predetermined period of time has elapsed since the launch of the aircraft device 1. In this way, the inertial device 100 supplies the second gyro data from the second gyroscope 120g, which corresponds to a large change in behavior from launch to water entry of the aircraft device 1, as selected gyro data to the aircraft device 1. Note that the predetermined fixed period is determined based on the configuration of the launch device and the aircraft device 1, assuming the time from launch to water entry and then underwater navigation.

[0038] The selection unit 103 receives the determination result from the determination unit 102 and selects the first gyro data from the first gyroscope 110g when a predetermined period of time has elapsed since the launch of the aircraft device 1. In this way, the inertial device 100 responds to small movements of the aircraft device 1 while it is traveling underwater, and supplies the first gyro data from the highly accurate first gyroscope 110g to the aircraft device 1 as selected gyro data.

[0039] Instead of using a timer function, the judgment unit 102 can analyze the first gyro data and the second gyro data and determine whether the aircraft device 1 is in the process of launch, entering the water, or navigating underwater based on changes in its behavior.

[0040] As described above, when the aircraft device 1 is an underwater vehicle, by selecting the second gyro data from the intensity detection type optical fiber gyroscope as the second gyroscope 120g from the time of launch to the time of entry into water, changes in the behavior of the aircraft device 1 can be reliably detected. During underwater navigation, the first gyro data from the dynamic tuning gyroscope serving as the first gyroscope 110g is selected, thereby enabling highly accurate detection of the behavior of the aircraft device 1. As a result, a highly reliable inertial device 100 can be realized that can supply the aircraft device 1 with gyro data that satisfies the detection range and accuracy requirements in accordance with the behavior of the aircraft device 1.

[0041] The above-described inertial device 100 uses a combination of a first inertial unit 110 equipped with a dynamically tuned gyroscope (DTG in FIG. 2) as the first gyroscope 110g and a second inertial unit 120 equipped with an intensity detection type fiber optic gyroscope (OP-FOG in FIG. 2) as the second gyroscope 120g. This makes it possible to select and output highly accurate gyro data at a lower cost and with a wider detection range than using a very expensive ring laser gyroscope (RLG in FIG. 2) alone.

[0042] Example (2): The aircraft device 1 is any of various mobile bodies that move on an orbit or perform attitude control in space, such as an artificial satellite, a space probe, or a spacecraft. The first inertial unit 110 includes a first gyroscope 110g, which is an optical fiber gyroscope, specifically an interferometric optical fiber gyroscope. The interferometric optical fiber gyroscope has high-precision characteristics. Therefore, the first inertial unit 110 is suitable for detecting the behavior of the aircraft device 1 during attitude control with high precision. The second inertial unit 120 includes a Coriolis vibration gyroscope as the second gyroscope 120g. The Coriolis vibration gyroscope has a wide detection range, making the second inertial unit 120 suitable for detecting sudden and large changes in the behavior of the aircraft device 1.

[0043] In the calculation unit 101, the determination unit 102 and the selection unit 103 perform the determination and selection as follows. The determination unit 102 analyzes the first gyro data and determines whether the detection range exceeds a predetermined threshold value. The predetermined threshold value is set to approximately 85% of the maximum detection range of the first gyro data output from the interferometric fiber optic gyroscope. If the first gyro data does not exceed a predetermined threshold, the determination unit 102 determines that the aircraft device 1 is in a normal state, moving along a trajectory or performing attitude control, and transmits the determination result to the selection unit 103. The selection unit 103 receives the determination result from the determination unit 102 and selects the first gyro data from the first gyroscope 110g. In this way, when the airframe 1 is in a normal state, the inertial device 100 supplies the first gyro data from the highly accurate first gyroscope 110g to the airframe 1 as selected gyro data.

[0044] If the first gyro data exceeds a predetermined threshold, the determination unit 102 determines that an abnormal state has occurred while the aircraft device 1 is moving along the trajectory or performing attitude control, and transmits the determination result to the selection unit 103. The selection unit 103 receives the determination result from the determination unit 102 and selects the second gyro data from the second gyroscope 120g having a wider detection range. In this way, the inertial device 100 responds to large behavioral changes in the aircraft device 1 in an abnormal state and supplies the second gyro data from the second gyroscope 120g, which is capable of responding to a wide detection range, to the aircraft device 1 as selected gyro data.

[0045] The behavior of the aircraft device 1 may suddenly change, exceeding the maximum detection range of the first gyroscope 110g, and the first gyro data selected as the selected gyro data may suddenly become saturated. In this case, the accuracy of the calculation of the attitude angle and azimuth angle by integrating the gyro data in the aircraft device 1 may be impaired. To prevent such problems, a buffer (not shown) that holds the first gyro data and the second gyro data for a certain period of time is provided in the calculation unit 101. The selection unit 103 goes back to the time when the first gyro data, for which the determination result was received from the determination unit 102, became saturated, and supplies the second gyro data held in the buffer to the aircraft device 1 as selected gyro data. The aircraft device 1 does not use the first gyro data after it became saturated, and instead uses the second gyro data, making it possible to reduce errors in the calculation of the attitude angle and azimuth angle by integration.

[0046] As described above, when the aircraft device 1 is a satellite, space probe, spacecraft, etc. that requires attitude control in outer space and is not in an abnormal state, the behavior of the aircraft device 1 can be detected with high accuracy by selecting the first gyro data from the interferometric optical fiber gyroscope as the first gyroscope 110g. When some abnormality occurs in the aircraft device 1, by selecting the second gyro data from the Coriolis vibration gyroscope as the second gyroscope 120g, it is possible to reliably detect any sudden and large changes in the behavior of the aircraft device 1 by following them. As a result, a highly reliable inertial device 100 can be realized that can supply the aircraft device 1 with gyro data that satisfies the detection range and accuracy requirements in accordance with the behavior of the aircraft device 1.

[0047] If the predetermined threshold value for switching the selection from the first gyro data to the second gyro data is set as the first threshold value, a second threshold value for switching the selection from the second gyro data back to the first gyro data can be set. In this case, the second threshold value is preferably smaller than the first threshold value to prevent malfunction. For example, the second threshold value is set to approximately 80% of the maximum detection range of the first gyro data output from the interferometric fiber optic gyroscope.

[0048] The determination unit 102 continues to analyze the first gyro data even after the first gyro data exceeds the first threshold, and determines whether the first gyro data that exceeded the maximum detection range has fallen below the second threshold. If the first gyro data falls below the second threshold, the determination unit 102 determines that the abnormal state while the aircraft device 1 was moving along the trajectory or performing attitude control has been resolved, and transmits the determination result to the selection unit 103. The selection unit 103 receives the determination result from the determination unit 102 and switches the selection from the second gyro data to the first gyro data. In this way, when the aircraft device 1 is in a normal state after the abnormal state has been resolved, the inertial device 100 can supply the first gyro data from the highly accurate first gyroscope 110g to the aircraft device 1 as selected gyro data. As a result, it is possible to realize a highly reliable inertial device 100 that can respond to large changes in the behavior of the aircraft device 1 in abnormal conditions and supply the aircraft device 1 with gyro data that can accommodate a wide detection range.

[0049] The above-described inertial device 100 uses a combination of a first inertial unit 110 equipped with an interferometric fiber optic gyroscope (i-FOG in FIG. 2) as the first gyroscope 110g and a second inertial unit 120 equipped with a Coriolis vibration gyroscope (MEMS in FIG. 2) as the second gyroscope 120g. This makes it possible to select and output highly accurate gyro data at a lower cost and with a wider detection range than using a very expensive ring laser gyroscope (RLG in FIG. 2) alone.

[0050] Example (3): The airframe device 1 is an aircraft or flying object such as an unmanned aerial vehicle (UAV). The first inertial unit 110 includes a fiber optic gyroscope, specifically an interferometric fiber optic gyroscope, as the first gyroscope 110g. The interferometric fiber optic gyroscope has a medium detection range and high accuracy, but may malfunction due to influences from the external environment (external factors). Therefore, it is suitable for detecting the behavior of the aircraft device 1 with high accuracy in a situation where there are no external factors. The second inertial unit 120 includes a Coriolis vibration gyroscope as the second gyroscope 120g. The Coriolis vibration gyroscope has a wide detection range and medium to low accuracy, but is less susceptible to the influence of the external environment and therefore less likely to output erroneous values.

[0051] In the calculation unit 101, the determination unit 102 and the selection unit 103 perform the determination and selection as follows. The determination unit 102 compares the first gyro data with the second gyro data, and if there is no difference between the first gyro data and the second gyro data that is greater than a certain amount, determines that the first gyro data is a correct value. Here, a difference greater than a certain amount means a difference that clearly exceeds the error that can occur when both the first gyro data and the second gyro data are normal. When the determination unit 102 determines that the first gyro data is a correct value, it notifies the selection unit 103 of the determination result to that effect. The selection unit 103 receives the determination result from the determination unit 102 and selects the first gyro data from the first gyroscope 110g. In this way, when the inertial device 100 determines that the first gyro data is correct, it supplies the first gyro data from the high-precision first gyroscope 110g to the aircraft device 1 as selected gyro data.

[0052] The determination unit 102 compares the first gyro data with the second gyro data, and if a difference of a certain amount or more occurs between the first gyro data and the second gyro data, determines that the first gyro data is an incorrect value. If the determination unit 102 determines that the first gyro data is an incorrect value, it notifies the selection unit 103 of the determination result that the first gyro data is incorrect. The selection unit 103 receives the determination result from the determination unit 102 and selects second gyro data from the second gyroscope 120g, which is less susceptible to the influence of the external environment. In this way, the inertial device 100 supplies the second gyro data from the second gyroscope 120g, which is less susceptible to the influence of the external environment, to the aircraft device 1 as selected gyro data instead of the first gyro data having an erroneous value.

[0053] The determination unit 102 continues to compare the first gyro data with the second gyro data even after a difference of a certain amount or more occurs between the first gyro data and the second gyro data. The determination unit 102 compares the first gyro data with the second gyro data, and if a difference of a certain amount or more does not occur between the first gyro data and the second gyro data, determines that the first gyro data is a correct value. When the determination unit 102 determines that the first gyro data is a correct value, it notifies the selection unit 103 of the determination result to that effect. The selection unit 103 receives the determination result from the determination unit 102 and switches the selection from the second gyro data to the first gyro data. In this way, the inertial device 100 can eliminate the condition in which the first inertial unit 110 outputs an incorrect value, and can supply the first gyro data from the high-precision first gyroscope 110g to the aircraft device 1 as selected gyro data. As a result, it is possible to realize a highly reliable inertial device 100 that can respond to changes in the external environment of the aircraft device 1 and supply the aircraft device 1 with gyro data that can accommodate a wide detection range.

[0054] The above-described inertial device 100 uses a combination of a first inertial unit 110 equipped with an interferometric fiber optic gyroscope (i-FOG in FIG. 2) as the first gyroscope 110g and a second inertial unit 120 equipped with a Coriolis vibration gyroscope (MEMS in FIG. 2) as the second gyroscope 120g. This makes it possible to select and output highly accurate gyro data at a lower cost and with a wider detection range than using a very expensive ring laser gyroscope (RLG in FIG. 2) alone.

[0055] Another example of specific example (3) will be described below. The first gyroscope 110g may malfunction due to sudden changes in the external environment, such as strong external electromagnetic radiation, lightning strikes, a decrease in altitude due to downbursts, or sudden temperature changes. In order to detect such sudden changes in the external environment, the inertial device 100 further includes a sensor 130 that measures the environment around or outside the aircraft device 1. The sensor 130 may be one or more of an electromagnetic wave sensor, an electric field sensor, an altitude sensor, a temperature sensor, or the like. Instead of comparing the first gyro data with the second gyro data, the determination unit 102 uses the detection result of the sensor 130 to determine the possibility that the external environment will affect the first inertial unit 110 and cause an error in the first gyro data. Furthermore, the determination unit 102 can use the detection results of various sensors that the aircraft device 1 has, instead of the sensor 130, to determine the possibility that the external environment will cause an error in the first gyro data.

[0056] The determination unit 102 refers to the detection result of the sensor 130, and if there is a low possibility that the external environment will affect the first inertial unit 110 and cause an error in the first gyro data, determines that the first gyro data is a correct value. Here, the degree of possibility of causing an error is determined in advance depending on the external environment to be detected. If the determination unit 102 determines that the first gyro data is a correct value, it notifies the selection unit 103 of the determination result indicating that the first gyro data is correct. The selection unit 103 receives the determination result from the determination unit 102 and selects the first gyro data from the first gyroscope 110g. In this way, when the inertial device 100 determines that the first gyro data is correct, it supplies the first gyro data from the high-precision first gyroscope 110g to the aircraft device 1 as selected gyro data.

[0057] The determination unit 102 refers to the detection result of the sensor 130, and if there is a high possibility that the external environment will affect the first inertial unit 110 and cause an error in the first gyro data, determines that the first gyro data is an incorrect value. If the determination unit 102 determines that the first gyro data is an incorrect value, it notifies the selection unit 103 of the determination result that the first gyro data is incorrect. The selection unit 103 receives the determination result from the determination unit 102 and selects second gyro data from the second inertial unit 120 equipped with a Coriolis vibration gyroscope. In this way, the inertial device 100 supplies the second gyro data from the second gyroscope 120g, which is less susceptible to the influence of the external environment, to the aircraft device 1 as selected gyro data instead of the first gyro data determined to be an erroneous value.

[0058] Even after determining that the first gyro data is an incorrect value due to the influence of the external environment, the judgment unit 102 continues to judge whether or not the external environment may affect the first inertial unit 110 and cause an error in the first gyro data. The determination unit 102 refers to the detection result of the sensor 130, and when the external environment that was affecting the first inertial unit 110 has disappeared and the possibility that the external environment will affect the first inertial unit 110 and cause an error in the first gyro data has decreased, the determination unit 102 determines that the first gyro data is a correct value. When the determination unit 102 determines that the first gyro data has changed from an incorrect value to a correct value, it notifies the selection unit 103 of the determination result that the first gyro data is correct. Upon receiving the determination result from the determination unit 102, the selection unit 103 switches the selection from the second gyro data to the first gyro data. In this way, the inertial device 100 can eliminate the condition in which the first inertial unit 110 outputs an incorrect value, and can supply the first gyro data from the high-precision first gyroscope 110g to the aircraft device 1 as selected gyro data.

[0059] In the above specific examples (1) to (3), it is possible to reverse the types of gyroscopes mounted on the first inertial unit 110 and the second inertial unit 120. Even in this case, the calculation unit 101 can appropriately select and output either the first gyro data or the second gyro data.

[0060] [Effects obtained by the embodiment] According to the first embodiment, the following effects can be obtained. (1) The inertial device 100 of embodiment 1 includes a first inertial unit 110 that generates first gyro data, a second inertial unit 120 that generates second gyro data using a method different from that of the first inertial unit, and a calculation unit 101, and generates gyro data used for navigation of the aircraft device 1. The calculation unit 101 compares the first gyro data with the second gyro data, or refers to data other than the first gyro data and the second gyro data, selects either the first gyro data or the second gyro data as selected gyro data, and supplies the selected gyro data to the aircraft device 1. Therefore, either the first gyro data or the second gyro data can be output appropriately in response to changes in the situation of the aircraft device 1.

[0061] The first inertial unit 110 is equipped with a first gyroscope 110g, and the second inertial unit 120 is equipped with a second gyroscope 120g. The first gyroscope 110g has higher accuracy than the second gyroscope 120g, and the second gyroscope 120g supports a wider detection range than the first gyroscope 110g. This makes it possible to select gyro data that satisfies the detection range and accuracy requirements in accordance with changes in the situation of the aircraft device 1 and supply it to the aircraft device 1, thereby satisfying both accuracy and detection range.

[0062] (1-1) In the inertial device 100 described above in (1), the first inertial unit 110 includes a dynamically tuned gyroscope, and the second inertial unit 120 includes an optical fiber gyroscope. The calculation unit 101 selects the second gyro data from the second gyroscope 120g from the time the airframe 1 is launched until it enters water, and selects the first gyro data from the first gyroscope 110g when the airframe 1 is traveling underwater. As a result, a highly reliable inertial device 100 can be realized that can supply the airframe 1 with gyro data that satisfies the detection range and accuracy requirements in accordance with the behavior of the airframe 1.

[0063] (1-2) In the inertial device 100 described in (1-1) above, the calculation unit 101 has a timer function for measuring the elapsed time from the time of launch, and determines that the device is currently traveling underwater when the elapsed time exceeds a predetermined value. This makes it possible to reliably determine whether the device 1 is currently traveling underwater or when it enters the water from the time of launch, and to appropriately output either the first gyro data or the second gyro data. As a result, it is possible to supply the device 1 with gyro data that satisfies the detection range and accuracy requirements according to the behavior of the device 1.

[0064] (1-3) In the inertial device 100 described in (1-1) above, the calculation unit 101 determines the behavior of the aircraft device 1 by analyzing the first gyro data and the second gyro data, and determines whether the aircraft device 1 is entering water or traveling underwater based on the behavior. This makes it possible to reliably determine whether the aircraft device 1 is traveling underwater from the time of launch to the time of entering water or traveling underwater, and appropriately output either the first gyro data or the second gyro data. As a result, it is possible to supply the aircraft device 1 with gyro data that satisfies the detection range and accuracy requirements according to the behavior of the aircraft device 1.

[0065] (2-1) In the inertial device 100 described in (1) above, the first inertial unit 110 includes an optical fiber gyroscope, and the second inertial unit 120 includes a Coriolis vibration gyroscope. If the first gyro data exceeds a predetermined threshold while the calculation unit 101 is selecting the first gyro data, the calculation unit 101 switches the selection from the first gyro data to the second gyro data. Therefore, if the first gyro data becomes saturated, the calculation unit 101 can appropriately switch the selection from the first gyro data to the second gyro data, and appropriately output either the first gyro data or the second gyro data.

[0066] (2-2) In the inertial device 100 described in (2-1) above, if the first gyro data falls below a predetermined threshold while the second gyro data is selected, the calculation unit 101 switches the selection from the second gyro data to the first gyro data. Therefore, if the saturation of the first gyro data is resolved after the first gyro data becomes saturated, the selection can be appropriately switched from the second gyro data to the first gyro data.

[0067] (3-1) In the inertial device 100 described in (1) above, the first inertial unit 110 includes an optical fiber gyroscope, and the second inertial unit 120 includes a Coriolis vibration gyroscope, and the calculation unit 101 switches the selection from the first gyro data to the second gyro data if the first gyro data becomes an erroneous value due to an external cause while the first gyro data is selected. Therefore, if the first gyro data becomes an erroneous value due to an external cause, the selection can be appropriately switched from the first gyro data to the second gyro data, and either the first gyro data or the second gyro data can be appropriately output.

[0068] (3-2) In the inertial device 100 described in (3-1) above, when the calculation unit 101 compares the first gyro data with the second gyro data and finds a difference of a certain level or more, it determines that the first gyro data is an erroneous value. Therefore, by comparing the first gyro data with the second gyro data, it can be reliably determined that the first gyro data has become an erroneous value, and the selection can be appropriately switched from the first gyro data to the second gyro data.

[0069] (3-3) The inertial device 100 described in (3-1) above further includes a sensor 130 that measures the external environment of the aircraft device 1, and the calculation unit 101 switches the selection from the first gyro data to the second gyro data when the external environment measured by the sensor 130 has the possibility of causing an error in the first gyro data while the first gyro data is selected. Therefore, by referring to the detection result of the sensor 130, it can be reliably determined that the first gyro data has become an erroneous value, and the selection can be appropriately switched from the first gyro data to the second gyro data.

[0070] (3-4) In the inertial device 100 described in (3-1) or (3-2) above, when the calculation unit 101 switches the selection from the first gyro data to the second gyro data and the erroneous value is resolved, the calculation unit 101 switches the selection from the second gyro data to the first gyro data. This makes it possible to compare the first gyro data with the second gyro data, reliably determine that the first gyro data has returned to the correct value after becoming an erroneous value, and appropriately switch the selection from the second gyro data to the first gyro data.

[0071] (3-5) In the inertial device 100 described above in (3-3), when the calculation unit 101 switches the selection from the first gyro data to the second gyro data and the external environment that may cause an error in the first gyro data is resolved, the calculation unit 101 switches the selection from the second gyro data to the first gyro data. Therefore, by referring to the detection result of the sensor 130, it can be reliably determined that the first gyro data has returned to the correct value after becoming an erroneous value, and the selection can be appropriately switched from the first gyro data to the second gyro data.

[0072] In the above (1-1) to (1-3), (2-1) to (2-2), and (3-1) to (3-5), the first inertial unit 110 and the second inertial unit 120, which generate gyro data by different methods, are used in combination. This makes it possible to select and output highly accurate gyro data at a lower cost, while also supporting a wider detection range, than using a very expensive ring laser gyroscope (RLG in FIG. 2) alone. [Explanation of symbols]

[0073] 1 aircraft device, 100 inertial device, 101 calculation unit, 102 judgment unit, 103 selection unit, 110 first inertial unit, 110g first gyroscope, 120 second inertial unit, 120g second gyroscope, 130 sensor, DTG dynamically tuned gyroscope, i-FOG interferometric optical fiber gyroscope, MEMS Coriolis vibration gyroscope using MEMS technology, Op-FOG intensity detection optical fiber gyroscope, RLG ring laser gyroscope.

Claims

1. An inertial device (100) that generates gyro data used for navigation of an airframe device (1), a first inertial unit (110) for generating first gyro data; a second inertial unit (120) that generates second gyro data in a manner different from that of the first inertial unit; a calculation unit (101) that compares the first gyro data with the second gyro data or refers to data other than the first gyro data and the second gyro data, selects one of the first gyro data and the second gyro data as selected gyro data, and supplies the selected gyro data to the aircraft device (1); An inertial device comprising:

2. The first inertial unit (110) is equipped with a first gyroscope (110g), The second inertial unit (120) is equipped with a second gyroscope (120g), The first gyroscope (110g) has a higher accuracy than the second gyroscope (120g), The second gyroscope (120g) has a wider detection range than the first gyroscope (110g).

10. The inertial device of claim 1.

3. the first inertial unit (110) comprises a dynamically tuned gyroscope; the second inertial unit (120) comprises a fiber optic gyroscope; The calculation unit (101) Selecting the second gyro data from the time of launching the aircraft device (1) to the time of entering water, Selecting the first gyro data when the aircraft device (1) is traveling underwater.

10. The inertial device of claim 1.

4. The calculation unit (101) A timer function is provided to measure the elapsed time from the injection time, determining that the underwater navigation is in progress when the elapsed time exceeds a predetermined value; 4. An inertial device according to claim 3.

5. The calculation unit (101) obtains a behavior of the aircraft device (1) by analyzing the first gyro data and the second gyro data, and determines whether the aircraft device (1) is entering water or traveling underwater based on the behavior.

4. An inertial device according to claim 3.

6. the first inertial unit (110) comprises a fiber optic gyroscope; the second inertial unit (120) comprises a Coriolis vibration gyroscope; When the first gyro data exceeds a predetermined threshold while the first gyro data is selected, the calculation unit (101) switches selection from the first gyro data to the second gyro data.

10. The inertial device of claim 1.

7. When the first gyro data falls below a predetermined threshold while the second gyro data is selected, the calculation unit (101) switches selection from the second gyro data to the first gyro data.

7. An inertial device according to claim 6.

8. the first inertial unit (110) comprises a fiber optic gyroscope; the second inertial unit (120) comprises a Coriolis vibration gyroscope; When the first gyro data becomes an erroneous value due to an external cause while the first gyro data is being selected, the calculation unit (101) switches selection from the first gyro data to the second gyro data.

10. The inertial device of claim 1.

9. The calculation unit (101) compares the first gyro data with the second gyro data, and when a difference of a certain value or more occurs, determines that the first gyro data is an incorrect value.

9. The inertial device of claim 8.

10. a sensor (130) for measuring an external environment of the aircraft body device (1); the calculation unit (101) switches selection from the first gyro data to the second gyro data when the external environment measured by the sensor (130) has a possibility of causing an error in the first gyro data while the first gyro data is selected; 9. The inertial device of claim 8.

11. When the selection is switched from the first gyro data to the second gyro data and the erroneous value is eliminated, the calculation unit (101) switches the selection from the second gyro data to the first gyro data.

10. An inertial device according to claim 8 or claim 9.

12. When the selection is switched from the first gyro data to the second gyro data, the calculation unit (101) switches the selection from the second gyro data to the first gyro data if the external environment that may cause an error in the first gyro data is eliminated.

11. An inertial device according to claim 10.

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