JP2006162292A - Position measuring system and navigation support system equipped with it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive position measuring system of a simple constitution, and to provide a navigation support system equipped with it. <P>SOLUTION: When the amount of change of GPS measurement values, before and after updates, exceeds a jump determining amount, a control part determines that this is a jump. The control part derives the moving speed, on the basis of the differences of distance between the occurrence of the jump and one sample previous and two samples previous and estimates a current position at the occurrence of the jump, on the basis that the moving speed is maintained. The control part simultaneously acquires the difference between a value, indicating the current position at the time of the occurrence of the jump and a GPS measurement value as a first correction value. The control part corrects GPS measurement values, after the occurrence of the jump through the use of the computed first correction value and computes the current position. When jump occurs again, after this, the control part computes a first correction amount again and performs a similar correction. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a position measurement system and a ship maneuvering support system including the position measurement system, and more particularly to a position measurement system that corrects an error included in a measurement signal and calculates a current position and a ship maneuvering support system including the position measurement system.

  In narrow waterways and congested water areas where there is a high risk of collision between ships and grounding, higher safe navigation is required compared to normal navigation. In particular, large ships such as tankers require a high level of maneuvering technology because of the large inertia of the hull. Such advanced marine vessel maneuvering technology is largely based on the experience and experience of ship operators and pilots. Furthermore, when the large ship is detached from or berthing, the ship operator cannot see the quay, and is forced to operate the ship under the eyes of the supervisor.

  In view of this, the introduction of a ship maneuvering support system that displays information such as the position and speed of a ship to a ship operator, a pilot guide, etc., and supports the ship so that it can be operated more safely has been promoted.

  Japanese Patent Application Laid-Open No. 2004-228688 discloses a door support device that attaches a self-contained positioning sensor composed of a millimeter wave radar device to a predetermined position of a ship and measures the distance to an object.

  In Patent Document 2, there is provided a marine vessel maneuvering support device that includes at least three cameras and calculates the relative positional relationship between the shoreline and the berthing line based on information captured by each camera. It is disclosed.

  In addition, a ship maneuvering support system using GPS (Global Positioning System) has been devised.

  GPS selects the optimal 3 to 4 satellites out of approximately 20 satellites orbiting about 20,000 meters above sea level, and exchanges signals with the selected satellites. Measure the current position. For this reason, when the satellite to be selected is switched, a “jump” in which the measurement signal from the GPS suddenly changes in the range of several tens of cm to several m occurs.

Therefore, the current position with high accuracy cannot be obtained only by the measurement signal from the GPS. Therefore, an RTK-GPS (Real Time Kinematics GPS) system that receives and corrects a measurement signal from another GPS arranged at a ground reference point is often used. In the RTK-GPS method, the current position can be obtained with an accuracy within a few centimeters.
JP 2003-276777 A JP 2004-175187 A

  The ship maneuvering support system as described above is manufactured according to a target route or water area, and needs to be applicable to an unspecified ship that navigates the route or water area.

  For this reason, it is desirable to bring a ship maneuvering support system when the pilot guides aboard a ship navigating the channel or water area.

  However, in the boat maneuvering support systems disclosed in Patent Documents 1 and 2, it is necessary to dispose a sensor or a camera on the hull, and it is impossible to carry.

  In addition, in the ship maneuvering support system using the RTK-GPS GPS, various devices are required as compared with the case of using only the GPS, so the system becomes large and difficult to carry. Further, the RTK-GPS method has a problem that it is very expensive.

  Accordingly, the present invention has been made to solve such a problem, and an object of the present invention is to provide a position measurement system having a simple configuration and at a low cost, and a ship maneuvering support system including the position measurement system.

  According to the present invention, a position measurement system comprising: a position measurement unit arranged on a moving body; and a position calculation device that calculates an error included in a measurement signal received from the position measurement unit and calculates a current position of the moving body. The position calculation device determines whether a sudden change exceeding a predetermined amount corresponding to the moving speed of the moving body has occurred in the measurement signal, and a sudden change in the measurement signal in the determination unit. The estimation means for estimating the current position based on the moving speed of the moving body derived from the change amount of the measurement signal before the sudden change occurs, and the difference between the estimated current position and the position indicated by the measurement signal A first correction amount calculation means for calculating a first correction amount for correcting an error included in the measurement signal, and a position indicated by the measurement signal as a current position if no sudden change occurs in the measurement signal; After an abrupt change occurs, and a first correcting means for the position indicated measurement signals by the correction values in a first correction amount and the current position.

  Preferably, the position calculating device corrects an initial error included in the measurement signal and an error accumulated due to excess or deficiency of correction in the first correction unit based on the first correction amount. Second correction amount calculating means for calculating a correction amount, and second correction means for setting a position indicated by a value obtained by further correcting the measurement signal with the second correction amount as a current position are further provided.

  Preferably, the second correction amount calculating means includes means for adding and averaging the first correction amounts for each calculation in the first correction amount calculating means to obtain a second correction amount. And means for adding or subtracting the second correction amount to or from the measurement signal within a predetermined rate of change.

  Moreover, according to this invention, it is a ship handling assistance system provided with the above-mentioned position measurement system.

  According to the present invention, whether or not an error has occurred is determined based on whether or not a measurement signal from the position measurement unit including the error has exceeded a predetermined amount according to the moving speed of the moving object to be measured. Further, if an error occurs, the correction amount is calculated based on the moving speed derived from the change amount immediately before the error occurs. Therefore, there is no need for a signal for correcting the measurement signal from the outside, and no device for that purpose is required. Therefore, the configuration can be simplified and an inexpensive position measurement system and a boat maneuvering support system including the position measurement system can be realized.

  Embodiments of the present invention will be described in detail with reference to the drawings. Note that the same or corresponding parts in the drawings are denoted by the same reference numerals and description thereof will not be repeated.

[Embodiment 1]
FIG. 1 is a schematic configuration diagram of a position measurement system 100 according to the first embodiment of the present invention.

  With reference to FIG. 1, the position measurement system 100 includes a GPS antenna 2, a GPS receiver 4, and a position calculation device 50.

  In the first embodiment, the GPS antenna 2 and the GPS receiving unit 4 implement a position measuring unit.

  The GPS antenna 2 is disposed at a location that serves as a reference point for measuring a current position on a mobile object that is a position measurement target, for example, a ship. The GPS antenna 2 receives radio waves from a plurality of satellites and outputs the received radio waves to the GPS receiver 4.

  The GPS receiver 4 measures the current position based on the position signal and the time signal from the satellite included in the radio wave received via the GPS antenna 2, and outputs the GPS measurement value to the position calculation device 50. In addition, the period when the GPS receiving unit 4 updates the GPS measurement value is about 1 to 2 seconds.

  By the way, when the GPS receiving unit 4 switches the satellite that transmits and receives signals, an error of about several tens of centimeters to several meters occurs irregularly in the GPS measurement value from the GPS receiving unit 4. The occurrence of such an error is called “jumping”.

  The position calculation device 50 includes an interface (I / F) unit 6, a control unit 8, a storage unit 10, a display unit 14, and an internal bus 12.

  In the first embodiment, the control unit 8 implements a determination unit, an estimation unit, a first correction amount calculation unit, and a first correction unit.

  The interface unit 6 connects the GPS reception unit 4 and the internal bus 12, receives GPS measurement values from the GPS reception unit 4, and outputs the GPS measurement values on the internal bus 12.

  The control unit 8 determines whether or not the GPS measurement value received from the GPS receiving unit 4 via the interface unit 6 and the internal bus 12 exceeds a predetermined amount according to the moving speed of the moving object that is the measurement target. Whether or not jumping has occurred, and if a jump has occurred, the first correction amount is calculated from the current position estimated based on the moving speed derived from the amount of change immediately before the jump occurs. Calculate. Then, if no jump occurs, the control unit 8 sets the GPS measurement value as the current position, and after the jump occurs, sets the value corrected by the calculated first correction amount as the current position. Further, the control unit 8 outputs the calculated current position to the display unit 14. Further, the control unit 8 outputs data to the storage unit 10 and receives data from the storage unit 10 as necessary.

  The storage unit 10 stores data received from the interface unit 6 and the control unit 8 via the internal bus 12, and outputs the stored data to the control unit 8 in response to a request from the control unit 8.

  The display unit 14 displays the current position received from the control unit 8 to users such as a ship operator and a pilot guide.

  The internal bus 12 connects the interface unit 6, the control unit 8, the storage unit 10, and the display unit 14 to mediate data exchange.

(Correction of GPS measurement value)
Since a moving object such as a ship, which is the object of measurement, has a large inertia, the amount of change in moving speed, that is, the acceleration is small. Therefore, within a period (about 1 to 2 seconds) in which the GPS receiver 4 updates the GPS measurement values, it can be considered that the moving body is moving at a constant speed with the previous speed.

  Therefore, when the GPS measurement value from the GPS receiving unit 4 greatly fluctuates, it is determined as a jump, and instead of the GPS measurement value, the current position is estimated assuming that the moving speed immediately before the jump occurs is maintained.

  In particular, it is preferable to measure a large ship of 10,000 tons or more.

  FIG. 2 is an example of time data when a jump occurs in the GPS measurement value. Note that the GPS receiver 4 outputs a measurement signal having components of latitude and longitude, but will be described as one-dimensional data in which the movement amounts of latitude and longitude are combined for simplicity.

  Referring to FIG. 2, when the amount of change before and after the update of the GPS measurement value exceeds the jump determination amount, the control unit 8 determines that it is jumping. Then, the control unit 8 derives the moving speed from the distance difference between the previous sample and the previous two samples from the time when the jump occurs, and estimates the current position at the time of the jump as maintaining the moving speed. At the same time, the control unit 8 sets the difference between the estimated current position value and the GPS measurement value as the first correction value. Further, the control unit 8 corrects the GPS measurement value after the jump occurrence using the calculated first correction value, and calculates the current position.

  Thereafter, when the jump occurs again, the control unit 8 calculates the first correction amount again and performs the same correction.

  The jump determination amount is determined according to the moving speed of the target moving body. As an example of the determination method, when the moving speed changes at the designed maximum acceleration, the distance that the moving body can move within the update period of the GPS measurement value can be used.

  FIG. 3 is a flowchart showing calculation processing of the current position according to the first embodiment.

  Referring to FIG. 3, control unit 8 sets the first correction amount A = 0 as the initial condition setting (step S100). Then, the control unit 8 sets the current positions L (n−1) and L (n−2) for the latest two samples as GPS measurement values (step S102).

  The control unit 8 adds the first correction amount A to the GPS measurement value and calculates the current position L (n) (step S104). Then, the control unit 8 determines whether or not the difference between the current position L (n) and the current position L (n−1) one sample before exceeds the jump determination amount ε (step S106).

  If the jump determination amount ε is exceeded (YES in step S106), that is, if it is determined that a jump has occurred, the control unit 8 determines the current position L (n−1) one sample before. And the current position L (n) is estimated by adding the moving speed derived from the amount of change between the current position L (n-2) two samples before and the current position L (n-1) one sample previous (step S108). ). Further, the control unit 8 calculates the first correction amount A from the difference between the estimated current position L (n) and the GPS measurement value (step S110).

  When the jump determination amount ε is not exceeded (NO in step S106), that is, when it is determined that no jump has occurred, or after the first correction amount A is calculated (step S110), control is performed. The unit 8 determines whether or not a processing end command is given from the user (step S112).

  When the process end command is not given (NO in step S112), the control unit 8 calculates the current position L (n) for the next sample (step S104).

  If the process end command is given (YES in step S112), control unit 8 ends the process.

  According to Embodiment 1 of the present invention, based on whether or not a change in the GPS measurement value that includes an error due to jumping exceeds the jump determination amount according to the moving speed of the moving object that is the measurement target has occurred. Judgment is made on whether there is a jump, and if a jump occurs, the current position is estimated based on the moving speed derived from the amount of change immediately before the jump occurs, and the error due to the jump is calculated from the estimated current position. A first correction amount for correction is calculated. After the jump occurs, the GPS measurement value is corrected with the first correction amount to obtain the current position. Therefore, it is not necessary to acquire a signal for correcting an error due to jumping from the outside, and a device for that purpose is not required. Therefore, it is possible to realize an inexpensive position measurement system with a simplified configuration.

[Embodiment 2]
In the second embodiment, a position measurement system further including a function for correcting an initial error included in a GPS measurement value and an accumulation error due to the first correction amount in the above-described first embodiment will be described.

  Since position measurement system according to the second embodiment has the same configuration as position measurement system 100 according to the first embodiment shown in FIG. 1, description thereof will not be repeated.

  In the second embodiment, the control unit 8 implements determination means, estimation means, first correction amount calculation means, first correction means, second correction amount calculation means, and second correction means.

  FIG. 4 is an example of time data when there is an initial error. Note that the moving object to be measured remains at the initial position.

  FIG. 4A shows GPS measurement values and time data of the current position calculated by the control unit 8.

  FIG. 4B is time data of the correction amount with respect to the GPS measurement value.

  Referring to FIG. 4A, in the initial state (in the case of 0 second), the GPS measurement value includes an error. In the position measurement system 100 according to the first embodiment described above, an error caused by the subsequent jump occurrence is corrected by the first correction amount, but the initial error is not corrected. Therefore, a value including an initial error may be calculated as the current position.

  When the initial error is small, there are few problems, but it is desirable to improve the accuracy. Therefore, the control unit 8 performs further correction based on the first correction amount.

  First, it can be considered that the value indicating the current position calculated by the control unit 8 includes a value indicating the true position and an error.

  Further, the GPS measurement value can be considered to include a value indicating the true position, a fluctuation value due to jumping, and other errors.

  As shown in FIG. 4 (a), assuming that fluctuation values due to jumping are X1, X2,..., Xn having a positive or negative sign,

Can be considered to hold.

  Accordingly, the first correction amount obtained from the difference between the value indicating the current position and the GPS measurement value for each jump is the value included in the value indicating the current position, and the GPS value because the value indicating the true position is canceled out. It is the total of the fluctuation value by jump included in the measured value.

  Furthermore, since the fluctuation value due to jump included in the GPS measurement value can be brought close to zero by averaging the first correction amount over a sufficiently long period, an error included in the value indicating the current position is obtained. be able to.

  In this way, a value obtained by averaging the first correction amounts is used as the second correction amount, and by further correcting with the second correction amount, a current position closer to the true position can be obtained. it can. The first correction amount and the second correction amount are time data as shown in FIG.

  Here, since the second correction amount shown in FIG. 4B changes stepwise with the change in the first correction amount, it is calculated by correcting the GPS measurement value as it is with the second fluctuation amount. The current position will change rapidly. Therefore, it is desirable to limit the correction by the second correction amount to a constant change rate. As the rate of change, for example, a value smaller than a jump determination amount for determining whether or not a jump has occurred is selected. FIG. 4B shows time data when the second correction amount is limited to a constant change rate.

  As described above, FIG. 4A shows the time data of the current position when the correction using the first correction amount and the correction using the second correction amount with a limited change rate are performed.

  Needless to say, the present invention can be similarly applied to the case where the moving object to be measured is moving.

  FIG. 5 is an example of time data of the position measurement system according to the second embodiment.

  FIG. 5A shows GPS measurement values and time data of the current position calculated by the control unit 8.

  FIG. 5B is time data of the correction amount with respect to the GPS measurement value.

  Referring to FIG. 5A, when the moving object to be measured is moving at a constant speed as shown in the true position, the control unit 8 The second correction amount is calculated to calculate the current position. According to the “Law of Large Numbers”, the accuracy increases as the number of arithmetic averages increases, so that the correction accuracy by the second correction amount increases as the number of jumps increases.

  Referring to FIG. 5B, the second correction amount approaches the error between the current position and the true position at the initial time shown in FIG. That is, it is shown that the initial error is sufficiently corrected by the second correction amount.

  In the above description, the case where the initial error included in the current position is corrected has been described. However, the second correction amount corrects the error between the true position and the current position calculated by the control unit 8. Thus, it is also possible to correct errors accumulated due to excessive or insufficient correction by the first correction amount.

  FIG. 6 is a flowchart showing calculation processing of the current position according to the second embodiment.

  In addition, the same step number is attached | subjected about the process same as the flowchart which shows the calculation process of the present position according to Embodiment 1 shown in FIG.

  Referring to FIG. 6, the control unit 8 sets the first correction amount A = 0, the second correction amount B = 0, the number of jumps j = 1, and the second correction amount (change rate) as initial condition settings. Restriction) δ = 0 (step S200). Then, the control unit 8 sets the current positions L (n−1) and L (n−2) for the latest two samples as GPS measurement values (step S102).

  The control unit 8 adds the first correction amount A to the GPS measurement value and calculates the current position L (n) (step S104). Then, the control unit 8 determines whether or not the difference between the current position L (n) and the current position L (n−1) one sample before exceeds the jump determination amount ε (step S106).

  If the jump determination amount ε is exceeded (YES in step S106), that is, if it is determined that a jump has occurred, the control unit 8 is the same as step S108 and step S110 shown in FIG. Process. Further, the control unit 8 adds the first correction amount A in the current sample to the product of the jump number j and the second correction amount B, that is, the sum of the first correction amount A up to the previous sample, and the number of jumps An average of the first correction amounts is calculated by dividing j by 1 and adding 1. Then, the control unit 8 updates the jump count j by adding 1 (step S202).

  When the jump determination amount ε is not exceeded (NO in step S106), or after the number of jumps is updated (step S202), the control unit 8 uses the second correction amount B and the second correction amount ( It is determined whether or not the difference in absolute value from (change rate limit) δ exceeds the change rate limit φ (step S204).

  When the difference between the second correction amount B and the second correction amount (change rate limit) δ exceeds the change rate limit φ (YES in step S204), the second correction amount B and the second correction amount B The second correction amount (change rate limit) δ is made closer to the second correction amount B by the size of the change rate limit φ according to the difference between the correction amount (change rate limit) δ of 2 (step S208). ).

  If the difference between the second correction amount B and the second correction amount (change rate limit) δ does not exceed the change rate limit φ (NO in step S204), the second correction amount (change rate). (Restriction) The second correction amount B is substituted for δ (step S206).

  Then, the control unit 8 subtracts the second correction amount (change rate limit) δ from the current position L (n) to obtain the current position L (n) (step S210). Furthermore, the control unit 8 determines whether or not a process end command is given from the user (step S112).

  When the process end command is not given (NO in step S112), the control unit 8 calculates the current position L (n) for the next sample (step S104).

  If the process end command is given (YES in step S112), control unit 8 ends the process.

  According to the second embodiment of the present invention, in addition to the effect of the first embodiment, the calculated current position and the true value are calculated by calculating the addition average of the first correction amount every time the GPS measurement value jumps. A second correction amount is derived for correcting the difference from the position. Therefore, it is possible to realize a position measurement system that further improves the calculation accuracy of the current position by further correcting the calculated current position using the derived second correction amount.

[Embodiment 3]
FIG. 7 is a schematic configuration diagram of a boat maneuvering support system 200 according to the third embodiment.

  Referring to FIG. 7, the boat maneuvering support system 200 includes a ship side device 60 and a ground side device 70.

  The ship upper side device 60 is arranged in a ship to be maneuvered. Then, the weather / sea state data is received from the ground side device 70 and the information is displayed to the operator. Further, the ship upper device 60 is obtained by adding the antenna unit 18 and the communication unit 16 to the position measurement system 100 shown in FIG. 1 and further replacing the control unit 8 with the control unit 30.

  The antenna unit 18 is connected to the communication unit 16, receives a radio wave transmitted from the ground side device 70, and outputs the radio wave to the communication unit 16.

  The communication unit 16 receives weather / sea state data such as wind direction, wind speed, and wave height transmitted from the ground side device 70 via the antenna unit 18.

  In addition to the function in the control unit 8 shown in the first or second embodiment, the control unit 30 calculates the current position, meteorological / sea state data received from the ground side device 70, and the topography of the target sea area stored in the storage unit 10. Based on the data or the like, information for performing a ship maneuvering support is displayed on the display unit 14 via an image / video.

  The ground side device 70 transmits weather / sea state data received from the outside to the ship side device 60 via the wireless communication means. The ground side device 70 includes a control unit 24, a communication unit 20, and an antenna unit 22.

  The control unit 24 outputs weather / sea state data received from the outside to the communication unit 20.

  The communication unit 20 converts the weather / sea state data received from the control unit 24 into a radio signal, and transmits the radio signal via the antenna unit 22.

  The antenna unit 22 radiates the radio signal received from the communication unit 20 to the ship-side device 60 through space.

  According to the third embodiment of the present invention, since it is not necessary to transmit a signal for correcting the current position from the ground side device, the configuration is simplified and an inexpensive ship maneuvering support system can be realized.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a schematic block diagram of the position measurement system according to Embodiment 1 of this invention. It is an example of time data when a jump occurs in a GPS measurement value. 6 is a flowchart showing calculation processing of a current position according to the first embodiment. It is an example of the time data in case an initial error is accompanied. It is an example of the time data of the position measurement system according to Embodiment 2. 10 is a flowchart showing a current position calculation process according to the second embodiment. FIG. 10 is a schematic configuration diagram of a boat maneuvering support system according to a third embodiment.

Explanation of symbols

  2 GPS antenna, 4 GPS receiving unit, 6 interface (I / F) unit, 8 control unit, 10 storage unit, 12 internal bus, 14 display unit, 16, 20 communication unit, 18, 22 antenna unit, 24, 30 control Part, 50 position calculation device, 60 ship side device, 70 ground side device, 100 position measurement system, 200 ship maneuvering support system, A first correction amount, B second correction amount, L (n) current position, X1, X2,..., N fluctuation value, j jump count, δ second correction amount (change rate limit), ε jump determination amount, φ change rate limit.

Claims (4)

Position measuring means arranged on the moving body;
A position calculation device that corrects an error included in a measurement signal received from the position measurement means and calculates a current position of the moving body;
The position calculation device includes:
Determining means for determining whether or not a sudden change exceeding a predetermined amount according to a moving speed of the moving body has occurred in the measurement signal;
When the determination unit causes the sudden change in the measurement signal, the current position is estimated based on the moving speed of the moving body derived from the change amount of the measurement signal before the sudden change occurs. Means,
First correction amount calculation means for calculating a first correction amount for correcting an error included in the measurement signal from a difference between the estimated current position and a position indicated by the measurement signal;
If the rapid change does not occur in the measurement signal, the position indicated by the measurement signal is set as the current position, and after the rapid change has occurred, the measurement signal is corrected by the first correction amount. And a first correction unit that uses the position indicated by the current position as the current position. The position calculation device includes:
Based on the first correction amount, a second correction amount for correcting an initial error included in the measurement signal and an error accumulated due to excessive or insufficient correction in the first correction means is calculated. A second correction amount calculating means;
The position measurement system according to claim 1, further comprising: a second correction unit that sets a position indicated by a value obtained by further correcting the measurement signal by the second correction amount as the current position. The second correction amount calculation means includes means for averaging the first correction amount for each calculation in the first correction amount calculation means to obtain the second correction amount,
The position measurement system according to claim 2, wherein the second correction means includes means for adding or subtracting the second correction amount to the measurement signal within a range of a predetermined change rate.   A marine vessel maneuvering support system comprising the position measurement system according to claim 1.

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