Inertial navigation device, control method for inertial navigation device, and control program for inertial navigation device

Abstract

This inertial navigation device (100) includes an inertia detection unit (10), a reception unit (20), and a control unit (50). When the reliability of the positioning accuracy of satellite positioning coordinates (PG) is less than a predetermined first threshold (ε), the control unit (50) corrects inertial navigation coordinates (PI) on the basis of satellite positioning coordinates (PG), and detects the corrected coordinates as the current coordinates (PA) for controlling a moving body (200). When the reliability of the positioning accuracy is equal to or greater than the first threshold (ε), the control unit (50) detects inertial navigation coordinates (PI) as the current coordinates (PA) for controlling the current moving body 200 without correcting the inertial navigation coordinates (PI) on the basis of the satellite positioning coordinates (PG).

Description

Inertial navigation system, inertial navigation system control method, and inertial navigation system control program

[0001] The present invention relates to an inertial navigation system, a control method for an inertial navigation system, and a control program for an inertial navigation system, and more particularly to an inertial navigation system mounted on a moving body, a control method for the inertial navigation system, and a control program for the inertial navigation system.

[0002] Inertial navigation systems mounted on moving objects have been known in the past. Such inertial navigation systems are disclosed, for example, in Japanese Patent Application Laid-Open No. 2018-101346.

[0003] Japanese Patent Application Laid-Open Publication No. 2018-101346 discloses an emergency call device (inertial navigation system) mounted on a vehicle (mobile body). This emergency call device detects its own vehicle position using positioning signals received from positioning satellites, and also detects its own vehicle position using inertial navigation. Specifically, this emergency call device detects its own vehicle position using the positioning signals until it determines that the positioning satellites have been lost, and then detects its own vehicle position using inertial navigation after it determines that the positioning satellites have been lost. Furthermore, when detecting its own vehicle position using inertial navigation, the vehicle position detected by inertial navigation is corrected by map matching.

[0004] Japanese Patent Application Laid-Open No. 2018-101346

[0005] However, a configuration that corrects the vehicle position detected by inertial navigation using map matching, such as the emergency notification device described in JP 2018-101346 A, is difficult to apply to mobile bodies, such as ships and aircraft, for which map matching is difficult due to the absence of roads around them. The same is true for cases where the vehicle position detected by inertial navigation is corrected using radar, such as radio radar, ultrasonic radar, laser radar, or infrared radar, although this is not described in JP 2018-101346 A. In other words, a configuration that performs correction using radar is difficult to apply to mobile bodies, such as ships and aircraft, for which it is difficult to obtain reflected waves from surrounding objects. For this reason, it is desirable to maintain and improve the detection accuracy of the position (coordinates) of a mobile body without performing correction using map matching or the like.

[0006] The present invention has been made to solve the above-mentioned problems, and one object of the present invention is to provide an inertial navigation system, a control method for an inertial navigation system, and a control program for an inertial navigation system that are capable of maintaining or improving the detection accuracy of the coordinates of a moving body without performing corrections such as map matching.

[0007] In order to achieve the above-mentioned object, an inertial navigation device according to a first aspect of the present invention is an inertial navigation device mounted on a moving body, and comprises an inertial detection unit that detects the acceleration and angular velocity of the moving body, a receiving unit that receives satellite signals from artificial satellites, and a control unit that acquires the inertial navigation coordinates of the moving body based on the detection results of the acceleration and angular velocity of the moving body, and the satellite positioning coordinates of the moving body based on the satellite signals, wherein if the reliability of the positioning accuracy regarding the satellite positioning coordinates is less than a predetermined first threshold, the control unit corrects the inertial navigation coordinates based on the satellite positioning coordinates and detects the corrected coordinates as the current coordinates of the moving body for control purposes, and if the reliability of the positioning accuracy is equal to or greater than the first threshold, the control unit does not correct the inertial navigation coordinates based on the satellite positioning coordinates, and detects the inertial navigation coordinates as the current coordinates of the moving body for control purposes.

[0008] As described above, the inertial navigation system according to a first aspect of the present invention includes a control unit that corrects the inertial navigation coordinates based on the satellite positioning coordinates and detects the corrected coordinates as the coordinates of the current moving body for control purposes when the reliability of the positioning accuracy regarding the satellite positioning coordinates is less than a predetermined first threshold, and detects the inertial navigation coordinates as the coordinates of the current moving body for control purposes without correcting the inertial navigation coordinates based on the satellite positioning coordinates when the reliability of the positioning accuracy is equal to or greater than the first threshold. This prevents satellite positioning coordinates with poor positioning accuracy and large errors from being reflected in the inertial navigation coordinates when the reliability of the positioning accuracy is equal to or greater than the first threshold, thereby maintaining the detection accuracy of the coordinates of the moving body. Furthermore, when the reliability of the positioning accuracy is less than the first threshold, correcting the inertial navigation coordinates based on the satellite positioning coordinates causes satellite positioning coordinates with good positioning accuracy and small errors to be reflected in the inertial navigation coordinates, thereby improving the detection accuracy of the coordinates of the moving body. As a result, the accuracy of detecting the coordinates of the moving object can be maintained and improved without performing corrections such as map matching.

[0009] In the inertial navigation system according to the first aspect, the control unit preferably corrects the inertial navigation coordinates based on the satellite positioning coordinates, detects the corrected coordinates as the current coordinates of the moving object under control, and then outputs a command to move the moving object from the current coordinates of the moving object under control to the inertial navigation coordinates before correction. With this configuration, even if the moving object deviates from the coordinates where it should be located (the inertial navigation coordinates before correction), it can be moved to the coordinates where it should be located. As a result, it is possible to reduce the deviation (misdistance) from the coordinates where it should be located.

[0010] In the inertial navigation system according to the first aspect, preferably, there are multiple types of satellites, the receiving unit receives satellite signals from each of the multiple types of satellites, and the control unit sequentially acquires the reliability of the positioning accuracy of any of the multiple types of satellites. If the acquired reliability of the positioning accuracy is less than a first threshold, the control unit corrects the inertial navigation coordinates based on the satellite positioning coordinates and detects the corrected coordinates as the coordinates of the current moving object for control purposes. If the acquired reliability of the positioning accuracy is equal to or greater than the first threshold, the control unit does not correct the inertial navigation coordinates based on the satellite positioning coordinates and detects the inertial navigation coordinates as the coordinates of the current moving object for control purposes. With this configuration, using multiple types of satellites can increase the number of situations in which the reliability of the positioning accuracy is less than the first threshold, compared to using only one type of satellite. As a result, even if the first threshold is set small, the number of situations in which the inertial navigation coordinates can be corrected based on the satellite positioning coordinates can be increased, thereby increasing the number of situations in which the detection accuracy of the moving object's coordinates can be improved.

[0011] In the inertial navigation system according to the first aspect, preferably, an equation indicating a positioning error regarding the satellite positioning coordinates is expressed by the following equation (1), the reliability of the positioning accuracy is DOP, the first threshold value is a threshold value of DOP, and the distance estimation error σ ｒ is multiplied by the first threshold value, the positioning error Err becomes the distance estimation error σ ｒ The value is three times or less. ｒ ×P (1) where, Err: positioning error σ ｒ : distance estimation error P: reliability of positioning accuracy.

[0012] With this configuration, the positioning error Err is reduced to the distance estimation error σ ｒ , the inertial navigation coordinates are not corrected based on the satellite positioning coordinates. As a result, it is possible to easily prevent the satellite positioning coordinates with poor positioning accuracy and large error from being reflected in the inertial navigation coordinates. In addition, when the positioning error Err is greater than three times the distance estimation error σ ｒWhen the difference between the measured values ​​and the actual values ​​is three times or less, the inertial navigation coordinates can be corrected based on the satellite positioning coordinates. As a result, the satellite positioning coordinates with high positioning accuracy and small error can be easily reflected in the inertial navigation coordinates.

[0013] In this case, preferably, the reliability of the positioning accuracy is HDOP, and the first threshold value is a threshold value of HDOP. With this configuration, HDOP is included in a message including information on satellite positioning coordinates acquired based on satellite signals, so that HDOP can be easily acquired as the reliability of the positioning accuracy when acquiring satellite positioning coordinates from the message.

[0014] In the above-described configuration for outputting a command to move the moving body from its current coordinates in the control to its pre-corrected inertial navigation coordinates, preferably, the control unit corrects the inertial navigation coordinates based on the satellite positioning coordinates and detects the corrected coordinates as the coordinates of the moving body in the control of the current, when the distance obtained by comparing the inertial navigation coordinates with the satellite positioning coordinates is equal to or greater than a predetermined second threshold and the reliability of the positioning accuracy is less than a first threshold, and detects the inertial navigation coordinates as the coordinates of the moving body in the control of the current, without correcting the inertial navigation coordinates based on the satellite positioning coordinates, when the distance obtained by comparing the inertial navigation coordinates with the satellite positioning coordinates is less than the second threshold. With this configuration, when the distance obtained by comparing the inertial navigation coordinates with the satellite positioning coordinates is equal to or greater than the second threshold and the reliability of the positioning accuracy is less than the first threshold, the inertial navigation coordinates are corrected based on the satellite positioning coordinates, and the corrected coordinates are detected as the coordinates of the moving body in the control of the current, and the moving body can be moved from its current coordinates in the control to the pre-corrected inertial navigation coordinates. As a result, if the moving body is deviating more than necessary from the coordinates where it should be, it can be moved to the coordinates where it should be. Furthermore, if the distance obtained by comparing the inertial navigation coordinates and the satellite positioning coordinates is less than the second threshold, the inertial navigation coordinates are not corrected based on the satellite positioning coordinates, so the inertial navigation coordinates are detected as the current coordinates of the moving body for control purposes, and it can continue moving to the destination. As a result, it is possible to prevent the current coordinates of the moving body from being corrected more than necessary and the moving body from the corrected current coordinates to the coordinates where it should be.

[0015] In this case, preferably, the control unit detects the magnitude of vibration of the moving body based on the acceleration of the moving body detected by the inertia detection unit, and adjusts the second threshold value based on the detected magnitude of vibration of the moving body. Here, if the second threshold value is relatively small, the control unit may perform an operation to move the moving body from its current coordinates in control to its coordinates where it should be located in small increments, which may cause the moving body to vibrate slightly. If the moving body is a vehicle, small vibrations of the moving body can cause a poor ride for occupants and passengers. Therefore, by adjusting the second threshold value based on the magnitude of the vibration of the moving body as described above, it is possible to reduce the vibration of the moving body when the moving body vibrates slightly. As a result, if the moving body is a vehicle, it is possible to improve the ride comfort for occupants and passengers.

[0016] In the configuration for determining whether the distance obtained by comparing the inertial navigation coordinates and the satellite positioning coordinates is equal to or greater than a predetermined second threshold, the control unit preferably adjusts the second threshold based on information about the remaining energy of the mobile object. Here, if the second threshold is relatively large, the operation of moving the mobile object from its current coordinates under control to its coordinates where it should be located is not performed for a relatively long time. In this case, the operation of moving the mobile object from its current coordinates under control to its coordinates where it should be located will involve a long distance. When the remaining energy of the mobile object is low, it is undesirable to perform a movement that consumes a large amount of energy. Therefore, by adjusting the second threshold based on information about the remaining energy of the mobile object as described above, the movement distance in the operation of moving the mobile object from its current coordinates under control to its coordinates where it should be located can be reduced when the remaining energy of the mobile object is low. As a result, the energy consumption of the mobile object can be reduced when the remaining energy of the mobile object is low.

[0017] In order to achieve the above-mentioned object, a control method for an inertial navigation device according to a second aspect of the present invention is a control method for an inertial navigation device mounted on a moving body, comprising the steps of detecting the acceleration and angular velocity of the moving body, receiving satellite signals from an artificial satellite, acquiring the inertial navigation coordinates of the moving body based on the detection results of the acceleration and angular velocity of the moving body and the satellite positioning coordinates of the moving body based on the satellite signals, and, if the reliability of the positioning accuracy regarding the satellite positioning coordinates is less than a predetermined threshold, correcting the inertial navigation coordinates based on the satellite positioning coordinates and detecting the corrected coordinates as the coordinates of the current moving body for control, if the reliability of the positioning accuracy is equal to or greater than the threshold, detecting the inertial navigation coordinates as the coordinates of the current moving body for control without correcting the inertial navigation coordinates based on the satellite positioning coordinates.

[0018] According to a second aspect of the present invention, the method for controlling an inertial navigation system includes, as described above, correcting the inertial navigation coordinates based on the satellite positioning coordinates when the reliability of the positioning accuracy of the satellite positioning coordinates is less than a predetermined threshold and detecting the corrected coordinates as the coordinates of the current moving body for control purposes, and detecting the inertial navigation coordinates as the coordinates of the current moving body for control purposes without correcting the inertial navigation coordinates based on the satellite positioning coordinates when the reliability of the positioning accuracy is equal to or greater than the threshold. This prevents satellite positioning coordinates with poor positioning accuracy and large error from being reflected in the inertial navigation coordinates when the reliability of the positioning accuracy is equal to or greater than the threshold, thereby maintaining the detection accuracy of the moving body's coordinates. Furthermore, correcting the inertial navigation coordinates based on the satellite positioning coordinates when the reliability of the positioning accuracy is less than the threshold allows satellite positioning coordinates with good positioning accuracy and small error to be reflected in the inertial navigation coordinates, thereby improving the detection accuracy of the moving body's coordinates. As a result, it is possible to provide a control method for an inertial navigation system that can maintain and improve the detection accuracy of the coordinates of a moving body without performing corrections such as map matching.

[0019] In order to achieve the above object, a control program for an inertial navigation device according to a third aspect of the present invention causes a computer to acquire inertial navigation coordinates of a moving body on which the inertial navigation device is mounted based on detection results of acceleration and angular velocity of the moving body, and satellite positioning coordinates of the moving body based on satellite signals from artificial satellites; if the reliability of the positioning accuracy regarding the satellite positioning coordinates is less than a predetermined threshold, correct the inertial navigation coordinates based on the satellite positioning coordinates and detect the corrected coordinates as the coordinates of the current moving body for control; if the reliability of the positioning accuracy is equal to or greater than the threshold, detect the inertial navigation coordinates as the coordinates of the current moving body for control without correcting the inertial navigation coordinates based on the satellite positioning coordinates.

[0020] According to a third aspect of the present invention, the control program for an inertial navigation system causes a computer to correct the inertial navigation coordinates based on the satellite positioning coordinates and detect the corrected coordinates as the coordinates of the current moving body for control purposes when the reliability of the positioning accuracy of the satellite positioning coordinates is less than a predetermined threshold, and to detect the inertial navigation coordinates as the coordinates of the current moving body for control purposes without correcting the inertial navigation coordinates based on the satellite positioning coordinates when the reliability of the positioning accuracy is equal to or greater than the threshold. This prevents satellite positioning coordinates with poor positioning accuracy and large error from being reflected in the inertial navigation coordinates when the reliability of the positioning accuracy is equal to or greater than the threshold, thereby maintaining the detection accuracy of the moving body's coordinates. Furthermore, when the reliability of the positioning accuracy is less than the threshold, the inertial navigation coordinates are corrected based on the satellite positioning coordinates, thereby improving the detection accuracy of the moving body's coordinates. As a result, it is possible to provide a control program for an inertial navigation system that can maintain and improve the detection accuracy of the coordinates of a moving object without performing corrections such as map matching.

[0021] According to the present invention, as described above, it is possible to maintain and improve the detection accuracy of the coordinates of a moving object without performing corrections such as map matching.

[0022] It is a block diagram showing a moving body and an inertial navigation system according to an embodiment. It is a schematic diagram for explaining detection of coordinates of a moving body according to an embodiment. It is a flowchart for explaining control processing related to detection of coordinates of a moving body according to an embodiment. It is a graph for explaining an example of control by an inertial navigation system according to an embodiment.

[0023] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0024] The configuration of an inertial navigation system 100 according to an embodiment of the present invention will be described with reference to FIGS.

[0025] (Overall Configuration of an Inertial Navigation System) As shown in Fig. 1, the inertial navigation system 100 is a device that detects the coordinates of a moving body 200. The inertial navigation system 100 is mounted on the moving body 200. The moving body 200 is, for example, a ship, an aircraft, or an automobile. The moving body 200 is equipped with a host device 210 that controls each part of the moving body 200, and a display unit 220 that displays information related to the movement of the moving body 200. For example, if the moving body 200 is an aircraft, the host device 210 is a flight computer.

[0026] The inertial navigation system 100 includes an inertial detection unit 10 , a receiving unit 20 , a memory 30 , a storage medium 40 , a control unit 50 , and a communication control unit 60 .

[0027] The inertial detection unit 10 detects the acceleration and angular velocity of the moving body 200. Specifically, the inertial detection unit 10 includes an acceleration sensor 11 and a gyroscope 12. The acceleration sensor 11 detects the acceleration of the moving body 200. The acceleration sensor 11 is a three-axis acceleration sensor. The gyroscope 12 detects the angular velocity of the moving body 200. The gyroscope 12 is a three-axis gyroscope.

[0028] The receiving unit 20 receives satellite signals from artificial satellites via the antenna 21. There are multiple types of artificial satellites. The receiving unit 20 receives satellite signals from each of the multiple types of artificial satellites. The receiving unit 20 is a GNSS receiver. The artificial satellites are, for example, satellites of satellite positioning systems such as GPS, GLONASS, Galileo, BeiDou, and QZSS. The receiving unit 20 acquires positioning results based on the received satellite signals and outputs the acquired positioning results. The receiving unit 20 outputs a GGA message in a format conforming to the NMEA international standard as the positioning result. The GGA message contains the satellite positioning coordinates P of the mobile unit 200. Ｇ , and satellite positioning coordinate P Ｇ It includes information such as the reliability of positioning accuracy (HDOP) for the location.

[0029] The memory 30 is a volatile memory such as a random access memory. The memory 30 stores information temporarily required when the control unit 50 performs control processing. The storage medium 40 is a non-volatile memory such as a hard disk drive or a solid state drive. The storage medium 40 stores various programs executed by the control unit 50. A control program 41 for the inertial navigation system 100 is stored in the storage medium 40. The control program 41 can be stored in the storage medium 40 by reading it from a non-transitory portable storage medium such as an optical disk or a USB memory, or by downloading it via a network. The control unit 50 executes the control program 41 to perform various processes for operating the inertial navigation system 100, such as a process for detecting the coordinates of the moving body 200.

[0030] The control unit 50 is a computer that includes a processor and controls each part of the inertial navigation system 100. The control unit 50 calculates the inertial navigation coordinates P Ｉ , and the satellite positioning coordinates P of the mobile unit 200 based on the satellite signals Ｇ The control unit 50 acquires the acquired inertial navigation coordinates P Ｉ and satellite positioning coordinates P Ｇ Based on this, the current coordinate P of the moving body 200 in the controlＡ The control unit 50 detects the coordinates P of the current moving object 200 in the control Ａ The host device 210 outputs the current coordinates P of the moving body 200 under control from the inertial navigation system 100 to the host device 210 via the communication control unit 60. Ａ For example, the host device 210 controls the movement of the moving object 200 based on the coordinates P of the current moving object 200 in the control so that the moving object 200 moves to the destination along a predetermined route. Ａ The movement of the moving body 200 is controlled based on the above.

[0031] The communication control unit 60 controls the communication of the inertial navigation system 100. The communication control unit 60 controls the communication between the receiving unit 20 and the control unit 50, and the communication between the control unit 50 and the higher-level device 210.

[0032] (Control related to detection of coordinates of moving body) The coordinates of the moving body 200 are detected as follows. As shown in FIG. 2, the control unit 50 acquires the detection results of the acceleration and angular velocity of the moving body 200 from the inertial detection unit 10. Based on the acquired detection results of the acceleration and angular velocity of the moving body 200, the control unit 50 calculates the inertial navigation coordinates P Ｉ Obtain the inertial navigation coordinate P Ｉ In order to obtain the inertial navigation coordinates P of the mobile body 200, the coordinates of the initial position are input in advance to the mobile body 200 (inertial navigation system 100). Usually, a position with specified coordinates, such as an airport, is input as the initial position, or an initial position acquired from a highly accurate positioning device outside the mobile body 200 is input. The control unit 50 calculates the inertial navigation coordinates P of the mobile body 200 by adding, to the initial position, movement components acquired from the detection results of the acceleration and angular velocity of the mobile body 200. Ｉ Specifically, the control unit 50 integrates the detection result of the acceleration of the mobile body 200 twice to obtain the translational movement component of the mobile body 200. The control unit 50 also integrates the detection result of the angular velocity of the mobile body 200 once to obtain the rotational movement component of the mobile body 200. The control unit 50 calculates the inertial navigation coordinate P by taking into account the translational movement component and the rotational movement component in the previous position (initially the initial position). Ｉ Obtain the inertial navigation coordinate P ＩThe control unit 50 calculates the inertial navigation coordinates P Ｉ is periodically acquired.

[0033] The control unit 50 acquires the GGA message from the receiving unit 20 via the communication control unit 60. The control unit 50 extracts the satellite positioning coordinates P Ｇ Extract and obtain the satellite positioning coordinates P Ｇ includes information on latitude, longitude, and altitude. At this time, the control unit 50 extracts and acquires from the GGA message the HDOP (Horizontal Dilution Of Precision) included in the GGA message as the reliability of the positioning accuracy. The control unit 50 extracts and acquires the satellite positioning coordinates P Ｇ The reliability of the positioning accuracy is periodically acquired. Note that the communication control unit 60 is not shown in FIG.

[0034] In this embodiment, when the reliability of the positioning accuracy is less than a predetermined threshold value ε, the control unit 50 Ｇ Inertial navigation coordinate P based on Ｉ The corrected coordinates are used as the current coordinates P of the moving body 200 in the control Ａ At this time, the control unit 50 detects the inertial navigation coordinates P Ｉ satellite positioning coordinates P Ｇ and the corrected coordinates are replaced with the satellite positioning coordinates P Ｇ In this case, the control unit 50 acquires the satellite positioning coordinate P Ｇ The coordinates P of the current moving object 200 in the control Ａ Furthermore, when the reliability of the positioning accuracy is equal to or greater than the threshold value ε, the control unit 50 detects the satellite positioning coordinate P Ｇ Inertial navigation coordinate P based on Ｉ Without correcting the inertial navigation coordinate P Ｉ The coordinates P of the current moving object 200 in the control ＡThe threshold value ε is set arbitrarily by a person, the host device 210, or the like when the inertial navigation system 100 is shipped or before the mobile body 200 is used. The threshold value ε can be reset. If the threshold value ε is set large, correction is performed even when the reliability of the positioning accuracy is low, thereby increasing the number of opportunities for correction. If the threshold value ε is set small, correction is performed only when the reliability of the positioning accuracy is good, thereby reducing the number of opportunities for correction. The threshold value ε is an example of a "first threshold value" in the claims.

[0035] Specifically, the control unit 50 sequentially acquires the reliability of the positioning accuracy of any of the multiple types of artificial satellites, and when the acquired reliability of the positioning accuracy is less than the threshold value ε, Ｇ Inertial navigation coordinate P based on Ｉ The corrected coordinates are used as the current coordinates P of the moving body 200 in the control Ａ If the reliability of the acquired positioning accuracy is equal to or greater than the threshold value ε, the satellite positioning coordinate P Ｇ Inertial navigation coordinate P based on Ｉ Without correcting the inertial navigation coordinate P Ｉ The coordinates P of the current moving object 200 in the control Ａ The receiver 20 sequentially outputs GGA messages from satellites of multiple types at predetermined time intervals. The controller 50 sequentially acquires the GGA messages output from the receiver 20. As a result, the controller 50 sequentially acquires the reliability of the positioning accuracy of any of the multiple types of satellites. The sequentially acquired reliability of the positioning accuracy is compared with a threshold value ε.

[0036] More specifically, the control unit 50 calculates the inertial navigation coordinate P Ｉ and satellite positioning coordinates P Ｇ If the distance compared with the above is equal to or greater than a predetermined threshold value δ and the reliability of the positioning accuracy is less than a threshold value ε, the satellite positioning coordinate P Ｇ Inertial navigation coordinate P based on Ｉ The corrected coordinates are used as the current coordinates P of the moving body 200 in the control Ａ and the inertial navigation coordinate P Ｉ and satellite positioning coordinates P ＧIf the distance compared with is less than the threshold value δ, the satellite positioning coordinate P Ｇ Inertial navigation coordinate P based on Ｉ Without correcting the inertial navigation coordinate P Ｉ The coordinates P of the current moving object 200 in the control Ａ At this time, the control unit 50 detects the inertial navigation coordinates P Ｉ and satellite positioning coordinates P Ｇ The distance compared with the inertial navigation coordinate P Ｉ and satellite positioning coordinates P Ｇ and determines whether the obtained three-dimensional distance is equal to or greater than a threshold value δ. The receiver 20 sequentially outputs GGA messages from artificial satellites of multiple types at predetermined time intervals. The controller 50 sequentially acquires the GGA messages output from the receiver 20. As a result, the controller 50 calculates the inertial navigation coordinates P Ｉ and the satellite positioning coordinates P of one of multiple types of artificial satellites Ｇ The three-dimensional distance between the inertial navigation coordinate P and the target position is sequentially acquired. The sequentially acquired three-dimensional distance is compared with a threshold value δ. The threshold value δ is arbitrarily set by a person or the host device 210 at the time of shipping the inertial navigation system 100, before using the mobile body 200, or while using the mobile body 200. The threshold value δ can be reset. If the threshold value δ is increased, the inertial navigation coordinate P Ｉ and satellite positioning coordinates P Ｇ If the three-dimensional distance between the coordinates is large, the correction is performed, and the number of correction opportunities is reduced. If the threshold value δ is made small, the inertial navigation coordinates P Ｉ and satellite positioning coordinates P Ｇ When the three-dimensional distance between is small, correction is performed, thereby increasing the chances of correction. The threshold value δ is an example of the "second threshold value" in the claims.

[0037] In this embodiment, the threshold value ε is set to the satellite positioning coordinate P Ｇ Here, the reliability of the positioning accuracy is HDOP, and the threshold value ε is a threshold value of HDOP. The threshold value ε is also a function of the distance estimation error σ ｒ is multiplied by the threshold ε, the positioning error Err is the distance estimation error σ ｒThat is, the threshold value ε is a value of 3 or less. As can be seen from the following equation (2), if the threshold value ε is a value of 3 or less, when HDOP is 3 or less, that is, when the positioning error Err is greater than or equal to the distance estimation error σ ｒ If the coordinates are less than three times the satellite positioning coordinates P Ｇ Inertial navigation coordinate P based on Ｉ That is, when the positioning error Err is small (when the positioning accuracy is good), the satellite positioning coordinate P Ｇ Inertial navigation coordinate P based on Ｉ The threshold value ε is, for example, 1. Err=σ ｒ ×P (2) where, Err: positioning error σ ｒ : distance estimation error P: reliability of positioning precision (HDOP).

[0038] Distance estimation error σ ｒ varies depending on the performance of the receiving unit 20 as a GNSS receiver and the reception environment of the satellite signals. If the performance of the receiving unit 20 and the reception environment of the satellite signals are poor, the distance estimation error σ ｒ becomes larger. DOP, including HDOP, changes depending on the geometric arrangement between the satellite and the receiving unit 20 serving as a GNSS receiver. If the geometric arrangement between the satellite and the receiving unit 20 serving as a GNSS receiver is poor, the DOP becomes larger. HDOP indicates the horizontal component of the reliability of positioning accuracy.

[0039] In this embodiment, the control unit 50 also calculates the satellite positioning coordinates P Ｇ Inertial navigation coordinate P based on Ｉ The corrected coordinates are used as the current coordinates P of the moving body 200 in the control Ａ After detecting the current coordinate P of the moving object 200 in the control Ａ to the inertial navigation coordinate P before correction Ｉ The command output from the inertial navigation system 100 is interrupted by a command to move the mobile body 200 along a route to the destination held and controlled by the host device 210. When the host device 210 receives an input of a command from the inertial navigation system 100, it outputs the coordinates P Ａto the inertial navigation coordinate P before correction Ｉ That is, the control unit 50 and the higher-level device 210 control the movement of the moving body 200 so that the moving body 200 moves in the direction of the coordinate P Ｂ When it is determined with a predetermined accuracy that the robot has deviated by a predetermined amount or more from the coordinate P Ｂ The moving object 200 is controlled to move toward the target point.

[0040] In this embodiment, the control unit 50 adjusts the threshold value δ in predetermined cases. For example, the control unit 50 detects the magnitude of vibration of the mobile body 200 based on the acceleration of the mobile body 200 detected by the inertia detection unit 10, and adjusts the threshold value δ based on the detected magnitude of vibration of the mobile body 200. In this case, for example, if the detected magnitude of vibration of the mobile body 200 is equal to or greater than a predetermined value, the control unit 50 adjusts the threshold value δ to be larger so as to reduce the vibration of the mobile body 200. Also, for example, the control unit 50 acquires information (such as information on the remaining amount of energy (fuel, electricity, etc.)) of the mobile body 200 from the higher-level device 210 (information on the remaining amount of energy, information on the amount of energy consumed, etc.), and adjusts the threshold value δ based on the acquired information on the remaining amount of energy of the mobile body 200. In this case, for example, if the remaining amount of energy of the mobile body 200 is equal to or less than a predetermined value, the control unit 50 adjusts the threshold value δ to be smaller so as to reduce the energy consumption of the mobile body 200.

[0041] (Control Process Related to Detection of Coordinates of Moving Body) Control processes related to detection of coordinates of the moving body 200 by the inertial navigation system 100 of this embodiment will be described based on a flowchart with reference to Fig. 3. Each process in the flowchart is executed by the control unit 50.

[0042] 3, in step S1, a GGA message is acquired from the receiver 20. The receiver 20 outputs a GGA message based on satellite signals from satellites at predetermined time intervals among a plurality of types of satellites. In step S1, a GGA message from one of the plurality of types of satellites is acquired.

[0043] Then, in step S2, it is determined whether the GNSS has been determined. The GNSS has been determined means that positioning based on the satellite signal of the artificial satellite was possible. Furthermore, the GNSS has not been determined means that positioning based on the satellite signal of the artificial satellite was not possible. In step S2, it is determined whether the GNSS has been determined based on the positioning status included in the GGA message.

[0044] In step S2, if it is determined that the GNSS is not determined, the process proceeds to step S1, and the process of step S1 is repeated. In this case, the satellite positioning coordinate P Ｇ Inertial navigation coordinate P based on Ｉ Since no correction is made to the inertial navigation coordinate P Ｉ is the current coordinate P of the moving object 200 under control. Ａ On the other hand, if it is determined in step S2 that the GNSS has been determined, the process proceeds to step S3.

[0045] Then, in step S3, the satellite positioning coordinate P Ｇ , and HDOP is obtained as the reliability of the positioning accuracy.

[0046] Then, in step S4, the inertial navigation coordinate P Ｉ is obtained.

[0047] Then, in step S5, the inertial navigation coordinates P Ｉ and the satellite positioning coordinate P obtained in step S3 Ｇ It is determined whether the three-dimensional distance between the inertial navigation coordinate P is equal to or greater than a threshold value δ. Ｉ and satellite positioning coordinates P Ｇ If it is determined that the three-dimensional distance between the satellite positioning coordinate P is less than the threshold value δ, the process proceeds to step S1, and the process of step S1 is repeated. Ｇ Inertial navigation coordinate P based on Ｉ Since no correction is made to the inertial navigation coordinate P Ｉ is the current coordinate P of the moving object 200 under control. ＡOn the other hand, in step S5, the inertial navigation coordinate P Ｉ and satellite positioning coordinates P Ｇ If it is determined that the three-dimensional distance between is equal to or greater than the threshold value δ, the process proceeds to step S6.

[0048] Then, in step S6, it is determined whether or not the HDOP, which is the reliability of the positioning accuracy acquired in step S4, is less than the threshold value ε. If it is determined that the HDOP is equal to or greater than the threshold value ε, the process proceeds to step S1, and the process of step S1 is repeated. In this case, the satellite positioning coordinate P Ｇ Inertial navigation coordinate P based on Ｉ Since no correction is made to the inertial navigation coordinate P Ｉ is the current coordinate P of the moving object 200 under control. Ａ On the other hand, if it is determined in step S6 that HDOP is less than the threshold value ε, the process proceeds to step S7.

[0049] Then, in step S7, the satellite positioning coordinate P Ｇ Inertial navigation coordinate P based on Ｉ That is, the inertial navigation coordinate P Ｉ satellite positioning coordinates P Ｇ The corrected coordinates are replaced with the satellite positioning coordinates P Ｇ Then, the process proceeds to step S1, and the process of step S1 is repeated. In this case, the satellite positioning coordinate P Ｇ Inertial navigation coordinate P based on Ｉ In order to correct the coordinates (i.e., the satellite positioning coordinates P Ｇ ) is the current coordinate P of the moving object 200 in terms of control. Ａ 3 is executed periodically at a predetermined cycle (for example, 1 to 2 Hz) while the inertial navigation system 100 is in operation.

[0050] (Example of control of inertial navigation system) Figure 4 shows an example of control of the inertial navigation system 100 of this embodiment. As shown in Figure 4, when the mobile body 200 moves between time T0 and time T1 along a predetermined route, the HDOP changes from moment to moment due to changes in the geometrical relationship between the artificial satellite and the inertial navigation system 100 as the mobile body 200 moves. In the inertial navigation system 100 of this embodiment, a determination is made as to whether or not correction is necessary depending on the HDOP that changes from moment to moment. That is, when the HDOP is equal to or greater than the threshold value ε, the satellite positioning coordinate P Ｇ Inertial navigation coordinate P based on Ｉ If the correction of is not performed and the HDOP is less than the threshold value ε, the satellite positioning coordinate P Ｇ Inertial navigation coordinate P based on Ｉ Correction is performed.

[0051] Specifically, in the inertial navigation system 100 of this embodiment, the inertial navigation coordinate P Ｉ and satellite positioning coordinates P Ｇ If the distance compared with is equal to or greater than the threshold value δ and the HDOP is less than the threshold value ε, the satellite positioning coordinate P Ｇ Inertial navigation coordinate P based on Ｉ The correction is performed on the satellite positioning coordinate P Ｇ Inertial navigation coordinate P based on Ｉ When the correction is performed, the current coordinate P of the moving body 200 in terms of control is Ａ to the inertial navigation coordinate P before correction Ｉ (That is, the coordinates P Ｂ 4, the dashed circle indicates the inertial navigation coordinate P Ｉ and satellite positioning coordinates P Ｇ 10 shows the timing when the distance compared with the threshold value δ is equal to or greater than the threshold value ε and the HDOP is less than the threshold value ε.

[0052] When the moving body 200 moves based on the coordinates detected by the inertial navigation system 100, the inertial navigation coordinates P Ｉ Due to the error included in Ａ and the actual coordinates of the moving body 200, that is, the coordinates P ＢA deviation (misdistance) occurs from the inertial navigation coordinate P Ｉ The error contained in is, for example, an error caused by the gyroscope 12. The gyroscope 12 may contain an error in the detection result due to the influence of heat generated by driving. In FIG. 4, the coordinate where the miss distance is 0 is the coordinate P where the gyroscope 12 should be located. Ｂ is illustrated as:

[0053] Satellite positioning coordinates P Ｇ Without using the inertial navigation coordinate P Ｉ In the comparative example using only the satellite positioning coordinate P Ｇ Inertial navigation coordinate P based on Ｉ Since the error correction is not performed, the miss distance accumulates as the moving body 200 moves. Therefore, the miss distance becomes D1 at time T1. In other words, the moving body 200 determines that it has reached the coordinates where the miss distance is 0 at time T1, but in reality, it reaches the coordinates that are shifted by D1 from there. On the other hand, in the inertial navigation system 100 of this embodiment, the satellite positioning coordinates P Ｇ Inertial navigation coordinate P based on Ｉ When the correction is performed, the current coordinate P of the moving body 200 in terms of control is Ａ (That is, satellite positioning coordinates P Ｇ ) to the uncorrected inertial navigation coordinate P Ｉ (That is, the coordinates P Ｂ ) The moving body 200 is moved to the target distance (D2) at the time when the correction is performed. Therefore, the miss distance is improved at the time when the correction is performed. Therefore, the miss distance at the time T1 becomes D2, which is smaller than D1 in the comparative example.

[0054] (Effects of this embodiment) In this embodiment, the following effects can be obtained.

[0055] In this embodiment, as described above, the satellite positioning coordinate P Ｇ is less than a predetermined threshold value ε, the satellite positioning coordinate P Ｇ Inertial navigation coordinate P based on Ｉ The corrected coordinates are used as the current coordinates P of the moving body 200 in the control ＡIf the reliability of the positioning accuracy is equal to or greater than the threshold value ε, the satellite positioning coordinate P Ｇ Inertial navigation coordinate P based on Ｉ Without correcting the inertial navigation coordinate P Ｉ The coordinates P of the current moving object 200 in the control Ａ As a result, when the reliability of the positioning accuracy is equal to or greater than the threshold value ε, the satellite positioning coordinate P Ｇ Inertial navigation coordinate P based on Ｉ If the correction is not performed, the positioning accuracy is poor and the satellite positioning coordinate P Ｇ is the inertial navigation coordinate P Ｉ Therefore, it is possible to maintain the detection accuracy of the coordinates of the moving body 200. Furthermore, when the reliability of the positioning accuracy is less than the threshold value ε, the satellite positioning coordinates P Ｇ Inertial navigation coordinate P based on Ｉ By performing the correction, the satellite positioning coordinate P Ｇ is the inertial navigation coordinate P Ｉ , thereby improving the detection accuracy of the coordinates of the moving body 200. As a result, the detection accuracy of the coordinates of the moving body 200 can be maintained or improved without performing correction by map matching or the like.

[0056] In this embodiment, as described above, the control unit 50 calculates the satellite positioning coordinates P Ｇ Inertial navigation coordinate P based on Ｉ The corrected coordinates are used as the current coordinates P of the moving body 200 in the control Ａ After detecting the current coordinate P of the moving object 200 in the control Ａ to the inertial navigation coordinate P before correction Ｉ As a result, the coordinates P where the moving body 200 should be located are obtained. Ｂ (Inertial navigation coordinates P before correction Ｉ ), the moving object 200 is positioned at the coordinate P Ｂ As a result, the coordinates P Ｂ This can improve the deviation (misdistance) from the target.

[0057] In this embodiment, as described above, there are multiple types of artificial satellites, the receiver 20 receives satellite signals from each of the multiple types of artificial satellites, and the control unit 50 sequentially acquires the reliability of the positioning accuracy of any of the multiple types of artificial satellites, and if the acquired reliability of the positioning accuracy is less than the threshold value ε, the satellite positioning coordinate P Ｇ Inertial navigation coordinate P based on Ｉ The corrected coordinates are detected as the coordinates of the current moving body 200 in terms of control, and if the reliability of the acquired positioning accuracy is equal to or greater than the threshold value ε, the satellite positioning coordinates P Ｇ Inertial navigation coordinate P based on Ｉ Without correcting the inertial navigation coordinate P Ｉ The coordinates P of the current moving object 200 in the control Ａ By using multiple types of satellites, it is possible to increase the number of situations where the reliability of the positioning accuracy is less than the threshold value ε compared to when only one type of satellite is used. As a result, even when the threshold value ε is set small, the satellite positioning coordinate P Ｇ Inertial navigation coordinate P based on Ｉ This increases the number of situations in which the correction can be performed, thereby increasing the number of situations in which the accuracy of detecting the coordinates of the moving body 200 can be improved.

[0058] In this embodiment, as described above, the satellite positioning coordinate P Ｇ The equation showing the positioning error regarding is expressed by the above equation (2), the reliability of the positioning accuracy is DOP (HDOP), the threshold value ε is a threshold value of DOP (HDOP), and the distance estimation error σ ｒ is multiplied by the threshold ε, the positioning error Err is the distance estimation error σ ｒ This is a value that is three times or less of the distance estimation error σ. ｒ If the value is greater than three times the satellite positioning coordinate P Ｇ Inertial navigation coordinate P based on Ｉ As a result, the positioning accuracy is poor and the satellite positioning coordinate P Ｇ is the inertial navigation coordinate P Ｉ In addition, it is possible to easily prevent the positioning error Err from being reflected in the distance estimation error σ ｒIf the coordinates are less than three times the satellite positioning coordinates P Ｇ Inertial navigation coordinate P based on Ｉ As a result, the satellite positioning coordinate P Ｇ is expressed as the inertial navigation coordinate P Ｉ can be easily reflected in

[0059] In this embodiment, as described above, the reliability of the positioning accuracy is HDOP, and the threshold value ε is a threshold value of HDOP. Thus, HDOP is calculated based on the satellite positioning coordinate P Ｇ Since the information is included in the message, the satellite positioning coordinate P Ｇ When obtaining the positioning accuracy, the HDOP can be easily obtained as the reliability of the positioning accuracy.

[0060] In this embodiment, as described above, the control unit 50 calculates the inertial navigation coordinates P Ｉ and satellite positioning coordinates P Ｇ If the distance compared with the above is equal to or greater than a predetermined threshold value δ and the reliability of the positioning accuracy is less than a threshold value ε, the satellite positioning coordinate P Ｇ Inertial navigation coordinate P based on Ｉ The corrected coordinates are used as the current coordinates P of the moving body 200 in the control Ａ and the inertial navigation coordinate P Ｉ and satellite positioning coordinates P Ｇ If the distance compared with is less than the threshold value δ, the satellite positioning coordinate P Ｇ Inertial navigation coordinate P based on Ｉ Without correcting the inertial navigation coordinate P Ｉ The coordinates P of the current moving object 200 in the control Ａ This detects the inertial navigation coordinate P Ｉ and satellite positioning coordinates P Ｇ If the distance compared with the threshold value δ is equal to or greater than the threshold value ε and the reliability of the positioning accuracy is less than the threshold value ε, the satellite positioning coordinate P Ｇ Inertial navigation coordinate P based on Ｉ In order to correct the coordinates, the corrected coordinates are used as the current coordinates P of the moving body 200 in the control Ａ After detecting the current coordinate P of the moving object 200 in the control Ａto the inertial navigation coordinate P before correction Ｉ As a result, the coordinates P where the moving body 200 should be located can be calculated. Ｂ If the moving object 200 is deviated from the coordinate P Ｂ In addition, the inertial navigation coordinate P Ｉ and satellite positioning coordinates P Ｇ If the distance compared with is less than the threshold value δ, the satellite positioning coordinate P Ｇ Inertial navigation coordinate P based on Ｉ Since no correction is made to the inertial navigation coordinate P Ｉ The coordinates P of the current moving object 200 in the control Ａ As a result, the current coordinates of the moving body 200 are corrected more than necessary, and the coordinates P where the moving body 200 should be located are deviated from the corrected current coordinates. Ｂ It is possible to suppress the movement of the particles to the

[0061] In this embodiment, as described above, the control unit 50 detects the magnitude of vibration of the moving body 200 based on the acceleration of the moving body 200 detected by the inertia detection unit 10, and adjusts the threshold value δ based on the detected magnitude of vibration of the moving body 200. Here, if the threshold value δ is relatively small, the control unit 50 adjusts the moving body 200 to the current coordinate P Ａ From the coordinate P where it should be located Ｂ When the moving body 200 is moved in small increments, the moving body 200 may vibrate slightly. If the moving body 200 is a vehicle, the small vibrations of the moving body 200 will make the ride uncomfortable for the crew and passengers. Therefore, as described above, by adjusting the threshold value δ based on the magnitude of the vibration of the moving body 200, the vibration of the moving body 200 can be reduced when the moving body 200 vibrates slightly. As a result, if the moving body 200 is a vehicle, the ride comfort for the crew and passengers can be improved.

[0062] In this embodiment, as described above, the control unit 50 adjusts the threshold value δ based on information about the remaining amount of energy of the moving object 200. Here, when the threshold value δ is relatively large, the moving object 200 is controlled to the current coordinate PＡ From the coordinate P where it should be located Ｂ In this case, the moving object 200 is not moved to the current coordinate P Ａ From the coordinate P where it should be located Ｂ In the operation of moving the moving body 200 to the current coordinate P, a long distance is traveled. When the remaining energy of the moving body 200 is low, it is not desirable to perform a movement that consumes a large amount of energy. Therefore, as described above, by adjusting the threshold value δ based on information regarding the remaining energy of the moving body 200, when the remaining energy of the moving body 200 is low, it is possible to move the moving body 200 to the current coordinate P Ａ From the coordinate P where it should be located Ｂ As a result, when the remaining amount of energy of the moving body 200 is low, the amount of energy consumed by the moving body 200 can be reduced.

[0063] (Modifications) The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the description of the above-mentioned embodiments, and includes all modifications (modifications) within the meaning and scope of the claims.

[0064] For example, in the above embodiment, an example was shown in which inertial navigation coordinates were corrected based on satellite positioning coordinates, the corrected coordinates were detected as the coordinates of the current moving body, and then a command was output to move the moving body from the current coordinates of the moving body in control to the inertial navigation coordinates before the correction. However, the present invention is not limited to this. The present invention does not necessarily require a configuration in which inertial navigation coordinates were corrected based on satellite positioning coordinates, the corrected coordinates were detected as the coordinates of the current moving body in control, and then a command was output to move the moving body from the current coordinates of the moving body in control to the inertial navigation coordinates before the correction. For example, when a pilot manually operates a moving body, a display may be displayed indicating that the moving body is currently located at coordinates different from the coordinates where it should be, or a movement amount for moving to the original route may be superimposed on the movement command input by the pilot.

[0065] In addition, in the above embodiment, an example was shown in which the receiver receives satellite signals from each of multiple types of artificial satellites, but the present invention is not limited to this. In the present invention, the receiver may be configured to receive satellite signals from only one type of artificial satellite.

[0066] Although the above embodiment has been described with reference to an example in which the reliability of the positioning accuracy is HDOP, the present invention is not limited to this. In the present invention, the reliability of the positioning accuracy may be a DOP other than HDOP, such as VDOP (Vertical Dilution Of Precision) or PDOP (Position Dilution Of Precision).

[0067] In the above embodiment, an example is shown in which the inertial navigation coordinates are corrected based on the satellite positioning coordinates when the distance obtained by comparing the inertial navigation coordinates with the satellite positioning coordinates is equal to or greater than the second threshold value and the reliability of the positioning accuracy is less than the first threshold value. However, the present invention is not limited to this. In the present invention, when determining whether or not to correct the inertial navigation coordinates based on the satellite positioning coordinates, it is not necessary to determine whether or not the distance obtained by comparing the inertial navigation coordinates with the satellite positioning coordinates is equal to or greater than the second threshold value.

[0068] In the above embodiment, the second threshold value is adjusted based on the magnitude of vibration of the moving body, but the present invention is not limited to this. The present invention does not necessarily require a configuration in which the second threshold value is adjusted based on the magnitude of vibration of the moving body.

[0069] In addition, in the above embodiment, an example was shown in which the second threshold value was adjusted based on information about the remaining amount of energy of the mobile body, but the present invention is not limited to this. In the present invention, the second threshold value does not have to be adjusted based on information about the remaining amount of energy of the mobile body.

[0070] 10 Inertial detection unit 20 Receiving unit 50 Control unit 100 Inertial navigation system 200 Mobile body P Ａ Current coordinates of the moving object on the control Ｇ Satellite positioning coordinates P Ｉ Inertial navigation coordinates δ threshold (second threshold) ε threshold (first threshold)

Claims

1. An inertial navigation system mounted on a moving body, an inertia detection unit that detects the acceleration and angular velocity of the moving body; a receiving unit that receives a satellite signal from an artificial satellite; a control unit that acquires an initial position of the moving body, inertial navigation coordinates of the moving body based on detection results of the acceleration and angular velocity of the moving body, and satellite positioning coordinates of the moving body based on the satellite signals; The control unit corrects the inertial navigation coordinates based on the satellite positioning coordinates when the reliability of the positioning accuracy regarding the satellite positioning coordinates is less than a predetermined first threshold, and detects the corrected coordinates as the current coordinates of the moving body for control purposes, and when the reliability of the positioning accuracy is equal to or greater than the first threshold, does not correct the inertial navigation coordinates based on the satellite positioning coordinates, and detects the inertial navigation coordinates as the current coordinates of the moving body for control purposes.

2. 2. The inertial navigation system according to claim 1, wherein the control unit corrects the inertial navigation coordinates based on the satellite positioning coordinates, detects the corrected coordinates as the current coordinates of the moving body in terms of control, and then outputs a command to move the moving body from the current coordinates of the moving body in terms of control to the inertial navigation coordinates before correction.

3. There are multiple types of artificial satellites, the receiving unit receives the satellite signals from each of the plurality of types of artificial satellites, 2. The inertial navigation device of claim 1, wherein the control unit sequentially acquires the reliability of the positioning accuracy of any of the plurality of types of artificial satellites, and if the acquired reliability of the positioning accuracy is less than the first threshold value, corrects the inertial navigation coordinates based on the satellite positioning coordinates and detects the corrected coordinates as the current coordinates of the moving body for control purposes, and if the acquired reliability of the positioning accuracy is equal to or greater than the first threshold value, does not correct the inertial navigation coordinates based on the satellite positioning coordinates, and detects the inertial navigation coordinates as the current coordinates of the moving body for control purposes.

4. The equation indicating the positioning error regarding the satellite positioning coordinates is expressed by the following equation (1): The reliability of the positioning accuracy is DOP, 2. The inertial navigation system according to claim 1, wherein the first threshold value is a DOP threshold value, and is a value such that when the distance estimation error σr is multiplied by the first threshold value, the positioning error Err is three times or less the distance estimation error σr. Err=σr×P...(1) where: Err: Positioning error σr: Distance estimation error P: Reliability of positioning accuracy is.

5. The reliability of the positioning accuracy is HDOP, 5. An inertial navigation system according to claim 4, wherein said first threshold is a threshold of HDOP.

6. 3. The inertial navigation device of claim 2, wherein the control unit corrects the inertial navigation coordinates based on the satellite positioning coordinates and detects the corrected coordinates as the current coordinates of the moving body for control purposes when the distance obtained by comparing the inertial navigation coordinates with the satellite positioning coordinates is equal to or greater than a predetermined second threshold and the reliability of the positioning accuracy is less than the first threshold, and when the distance obtained by comparing the inertial navigation coordinates with the satellite positioning coordinates is less than the second threshold, the control unit does not correct the inertial navigation coordinates based on the satellite positioning coordinates and detects the inertial navigation coordinates as the current coordinates of the moving body for control purposes.

7. 7. The inertial navigation system according to claim 6, wherein the control unit detects a magnitude of vibration of the moving body based on the acceleration of the moving body detected by the inertial detection unit, and adjusts the second threshold value based on the detected magnitude of vibration of the moving body.

8. The inertial navigation system according to claim 6 , wherein the control unit adjusts the second threshold value based on information relating to a remaining amount of energy of the moving body.

9. A control method for an inertial navigation system mounted on a moving body, comprising: detecting an acceleration and an angular velocity of the moving object; receiving a satellite signal from a satellite; acquiring inertial navigation coordinates of the moving body based on the initial position of the moving body and the detection results of the acceleration and angular velocity of the moving body, and satellite positioning coordinates of the moving body based on the satellite signals; a step of correcting the inertial navigation coordinates based on the satellite positioning coordinates and detecting the corrected coordinates as the current coordinates of the moving body for control purposes when the reliability of the positioning accuracy regarding the satellite positioning coordinates is less than a predetermined threshold, and detecting the inertial navigation coordinates as the current coordinates of the moving body for control purposes without correcting the inertial navigation coordinates based on the satellite positioning coordinates when the reliability of the positioning accuracy is equal to or greater than the threshold.

10. On the computer, acquiring inertial navigation coordinates of the moving body based on an initial position of the moving body on which the inertial navigation system is mounted and detection results of the acceleration and angular velocity of the moving body, and satellite positioning coordinates of the moving body based on satellite signals from artificial satellites; When the reliability of the positioning accuracy regarding the satellite positioning coordinates is less than a predetermined threshold, correcting the inertial navigation coordinates based on the satellite positioning coordinates and detecting the corrected coordinates as the current coordinates of the moving body in terms of control, and when the reliability of the positioning accuracy is equal to or greater than the threshold, not correcting the inertial navigation coordinates based on the satellite positioning coordinates and detecting the inertial navigation coordinates as the current coordinates of the moving body in terms of control; A control program for an inertial navigation system that executes the above.