Integrated satellite navigation and dead-reckoning navigation positioning device

TECHNICAL FIELD

0001The present invention relates to an integrated satellite navigation and dead-reckoning navigation positioning device that integrates an observation obtained by receiving a positioning signal from a navigation satellite and an observation obtained from a dead-reckoning navigation device to perform positioning.

BACKGROUND ART

0002There have been known various configurations in terms of which observation to use for positioning and how to integrate the observations for positioning in a satellite navigation/dead-reckoning navigation integrated positioning device (hereinafter, referred to as "GPS/DR integrated positioning device") in which an observation (hereinafter, referred to as "GPS observation") obtained from a GPS positioning system, for example, as a non-autonomous system, and an observation (hereinafter, referred to as "DR observation") obtained from a dead-reckoning navigation system (DR: dead-reckoning navigation system), as an autonomous system, are integrated (for example, see Patent Documents 1 and 2).

0003Which type of configuration is employed in order to integrate the GPS observation and the DR observation largely depends on the cost of the device, required accuracy and the like. <figref idref="f0001">Fig. 1</figref> is a block diagram of a typical example of the aforementioned integration type.

0004<figref idref="f0001">Fig. 1(A)</figref> shows a loosely-coupled approach, and <figref idref="f0001">Fig. 1(B)</figref> shows a tightly-coupled approach and a deeply-coupled approach.

0005In <figref idref="f0001">Fig. 1(A)</figref>, a tracking processing module 11 tracks a phase of a GPS positioning signal of a baseband obtained by receiving a signal from a GPS satellite, and finds a position, a velocity, and the like of each satellite. A GPS positioning calculation module 12 finds a position and a velocity at a receiving point based on a pseudo range (PR), a Doppler frequency observation and the position and velocity of each satellite found by the tracking processing module 11. A DR positioning calculation module 13 finds the position and velocity based on external support data of an inertial sensor and the like. Then, an integrated positioning calculation module 14 integrates the GPS observation, such as the position and velocity obtained by the GPS positioning calculation module 12 and the DR observation, such as the position and velocity obtained by the DR positioning calculation module 13 to provide the position and velocity of higher quality to a user.

0006In <figref idref="f0001">Fig. 1(B)</figref>, a tracking processing module 21 tracks a phase of a GPS positioning signal of a baseband obtained by receiving a signal from a GPS satellite, and finds a position, a velocity, and the like of each satellite. In the case of the tightly-coupled approach, an integrated positioning calculation module 22 integrates a pseudo range and a Doppler frequency obtained by the tracking processing module 21 as the GPS observation and an external support data of the inertial sensor and the like as the DR observation in one integrated positioning calculation module 22 to provide the position and velocity of higher quality to a user.

0007In the case of the deeply-coupled approach, the integrated positioning calculation module 22 uses a baseband complex signal (I, Q) obtained by the tracking processing modules 21 as the GPS observation and an external support data of the inertial sensor as the DR observation to perform an integrated positioning calculation.

0008Note that the GPS positioning calculation module 12 and the integrated positioning calculation module 14 of the loosely-coupled approach and the integrated positioning calculation module 22 of the tightly/deeply-coupled approach are also referred to as a "navigation filter" in which usually the position and position error, the velocity and velocity error, inertial sensor error and the like are estimated by a Kalman filter, and the estimated respective errors are negatively fed back as a correction amount to a certain portion to be corrected.

0009In PNDs (Portable Navigation Devices) for personal and vehicle use, which have attracted attention in recent years, lower price and higher accuracy are required. For this reason, as disclosed in Patent Documents 1 and 2, being used is a device which integrates the external support data of a low-price inertial sensor (such as a gyroscope and an acceleration sensor), map data and the like, and the GPS observation using the loosely-coupled approach or the tightly-coupled approach.

0010<ul id="ul0001" list-style="none" compact="compact"><li>Patent Document 1: <patcit id="pcit0001" dnum="JP2007093483A"><text>JP 2007-93483(A</text></patcit>)</li><li>Patent Document 2: <patcit id="pcit0002" dnum="US6643587B"><text>U.S. No. 6,643,587</text></patcit></li></ul>

0011However, the GPS/DR integrated positioning device of related art, including Patent Documents 1 and 2, has had problems as described below. <ol id="ol0001" compact="compact" ol-style=""><li>(1) In the loosely-coupled approach, the data of the position, velocity, and the like at the receiving point found by the GPS positioning calculation module and the position and velocity found by the DR positioning calculation module are integrated, Thus, in the loosely-coupled approach, until a result of the GPS positioning calculation is obtained, the GPS data cannot be utilized for calculation of the DR positioning. A general method for the GPS positioning needs at least four satellites to find four variables of a three-dimensional position (X, Y, Z) and a time. However, for the reason above, unless signals from four or more satellites can be acquired and tracked, the GPS data cannot be utilized for the DR calculation. Further, the biggest drawback of the loosely-coupled approach is the error of the position and velocity obtained from the GPS positioning calculation module 12 being colored noise, which does not meet a white noise error condition as an indispensable requirement of a Kalman filter in the integrated positioning calculation module 22. </li><li>(2) In the tightly-coupled approach, the pseudo range and Doppler frequency as the GPS observation, and the DR observation are integrated in one integrated positioning calculation module; therefore, detailed knowledge about the GPS is required to design the Kalman filter. Furthermore, compared with the loosely-coupled approach, the integrated positioning calculation module has a very complex design. Additionally, when an abnormality occurs in an output from the inertial sensor, for example, the position, velocity, attitude or the like (hereinafter, referred to as navigation data) cannot be provided to the user. </li><li>(3) In the deeply-coupled approach, a positioning result fed back to the tracking processing model of the GPS positioning signal is affected by an input valve (such as map-match data) from the sensor module and the user. For this reason, for example, if the abnormal sensor data is input, the GPS satellite cannot be tracked to make it impossible to detect the abnormality of the sensor using the GPS positioning results.</li></ol>

0012In this way, a method for detecting an abnormality is very important technology, particularly in the case of using the inertial sensor, which has low reliability, but is low in cost in order to balance the cost with the performance. However, the GPS/DR integrated positioning device of related art, including Patent Documents 1 and 2, cannot determine the abnormality of the output of the positioning calculation module due to the abnormality of the external support data of the inertial sensor and the like.

0013Consequently, and object of the invention is to provide a satellite navigation/dead-reckoning navigation integrated positioning device which can be constituted by low cost, and in which accuracy of the navigation data including the position and velocity is improved.

0014<patcit id="pcit0003" dnum="US6697736B"><text>US 6697736</text></patcit> discloses a positioning and navigation method and system which can enhance the performance of a global positioning and inertial integration system even when GPS satellite signals are not available. <patcit id="pcit0004" dnum="US5906655A"><text>US 5906655</text></patcit> discloses a method for monitoring integrity of an integrated GPS and IMU system. Position estimates are calculated from the GPS data and IMU data and then compared to determine the validity of the estimates. <patcit id="pcit0005" dnum="JP8050024A"><text>JP 08-050024</text></patcit> describes a navigation device for a vehicle which finds the position of a vehicle based on signals from an angular velocity sensor, a vehicle velocity sensor and a GPS receiver when the angular velocity sensor is detected to be normal, and only on the signal from the GPS receiver when the angular velocity sensor is judged to be abnormal. <patcit id="pcit0006" dnum="EP1260831A"><text>EP 1260831</text></patcit> describes a hybrid processing apparatus which can indicate a current position of a moveable body on the basis of self-contained positioning data and GPS measurement data. Self-contained positioning data and GPS data are combined in dependence on the determination of an estimated error of the self-contained positioning data.

0015According to the present invention there is provided an integrated satellite navigation and dead-reckoning navigation positioning device as defined in claim 1.

0016Preferred features of the invention are recited in the dependent claims.

0017The present invention may provide the advantage that unlike the loosely-coupled approach of related art, even in a state where a satellite navigation positioning calculation is impossible or is not completed, the position and velocity of the moving body can be found based on the pseudo range and Doppler frequency information already observed. Further, if the external support data becomes abnormal and thus the integrated positioning calculation is impossible, a calculation result by the satellite navigation positioning calculation module can be provided to an user. <ul id="ul0002" list-style="none" compact="compact"><li>(2) The external support data may include, for example, data by an inertial sensor, and the abnormality determination module may compare the result of the positioning calculation by the satellite navigation positioning calculation module with the data by the inertial sensor to determine the abnormality of the inertial sensor. With the aforementioned configuration, the abnormality of the inertial sensor can be detected; therefore, positioning accuracy can be prevented from lowering due to the use of the inertial sensor in an abnormality state. </li><li>(3) The external support data may include, for example, map data input information, and the abnormality determination module may compare the result of the positioning calculation by the satellite navigation positioning calculation module with the map data to determine the abnormality of the map data input information. With the aforementioned configuration, the abnormality of the map data input information can be detected; therefore, positioning accuracy can be prevented from lowering due to the use of the abnormal map data. </li><li>(4) The abnormality determination module may compare the result found by the satellite navigation positioning calculation module with the result found by the integrated positioning calculation module to determine the abnormality of the result of the calculation of the integrated positioning calculation module. With the aforementioned configuration, the abnormality of the external support data used for the integrated positioning calculation or the abnormality of the integrated positioning calculation module can be detected; therefore, the abnormal navigation data can be prevented from being provided to the user. </li><li>(5) A module may be provided to output the calculation results by the satellite navigation positioning calculation module to the user if the abnormality determination module determines an abnormality. The user may be informed of the abnormality state along with the calculation result. With the aforementioned configuration, even if the abnormality state is determined, the calculation result of the satellite navigation positioning calculation module can be obtained. Additionally, if the abnormality state is output to the user, the user can grasp the abnormality state. </li><li>(6) The integrated positioning calculation module, when, for example, resuming the positioning calculation from a state where the integrated positioning calculation module is stopped due to the abnormality of the external support data, may resume the integrated positioning calculation using the position and the velocity found by the satellite navigation positioning calculation module as initial values. This makes it possible for the integrated positioning calculation module to quickly obtain the positioning result when recovering from the down state of the integrated positioning calculation. </li><li>(7) The integrated positioning calculation module may execute the positioning calculation based on the pseudo range and the Doppler frequency information by a single difference between satellites found by the tracking processing module.</li></ul>

0018In this way, if the positioning calculation is performed based on the single difference between satellites, the integrated positioning calculation module does not need to estimate a clock error of a receiver and changes thereof by the Kalman filter. Therefore, not only a computational load of the Kalman filter in the integrated positioning calculation module can be reduced, but also the clock error and a model of the changes thereof do not need to be considered.

0019According to the invention, unlike the loosely-coupled approach of related art, even in a state, for example, where the satellite navigation positioning calculation is impossible or is not completed with the positioning signals from four or more navigation satellites not being received, the position and velocity of the moving body can be obtained based on the pseudo range and Doppler frequency information already observed. Further, in a case where the external support data becomes abnormal and thus the integrated positioning calculation is impossible, the calculation result by the satellite navigation positioning calculation module can be provided to the user.

0020Preferred features of the present invention will now be described, purely by way of example, with reference to the accompanying drawings, in which: <ul id="ul0003" list-style="none" compact="compact"><li><figref idref="f0001">Figs. 1(A) and 1(B)</figref> are block diagrams showing typical configuration examples of an integration type of a satellite navigation/dead-reckoning navigation integrated positioning device of related art.</li><li><figref idref="f0002">Fig. 2</figref> is a block diagram showing a configuration of a satellite navigation/dead-reckoning navigation integrated positioning device according to a first embodiment.</li><li><figref idref="f0003">Fig. 3</figref> is a flowchart showing a procedure of abnormality determination of an integrated positioning calculation module executed by an output judgment module of the satellite navigation/dead-reckoning navigation integrated positioning device.</li><li><figref idref="f0004">Fig. 4</figref> is a flowchart showing a procedure of abnormality determination of external support data executed by the output judgment module of the satellite navigation/dead-reckoning navigation integrated positioning device.</li><li><figref idref="f0005">Fig. 5</figref> is a flowchart showing a procedure of abnormality determination of another external support data executed by the output judgment module of the satellite navigation/dead-reckoning navigation integrated positioning device.</li><li><figref idref="f0006">Fig. 6</figref> is a block diagram showing a configuration of a satellite navigation/dead-reckoning navigation integrated positioning device according to a second embodiment.</li></ul>

0021Hereinafter, several specific embodiments are described.

FIRST EMBODIMENT

0022<figref idref="f0002">Fig. 2</figref> is a block diagram showing a configuration of a satellite navigation/dead-reckoning navigation integrated positioning device according to a first embodiment.

0023A GPS receiving circuit 30 converts a positioning signal from a satellite received by a GPS antenna into an intermediate frequency and A/D-converts it to output a so-called baseband GPS positioning signal.

0024A sensor module 40 is an external device, which includes at least an acceleration sensor, an angular velocity sensor, and a gyroscope inertial sensor, for obtaining orientation information and outputs external support data.

0025For the external support information other than the value obtained by the above various sensors, used are map position input information (map-match data) or error input information of the map position (map-match data error) input by a user.

0026A tracking processing module 31 performs, based on the above GPS positioning signal, acquisition processing and tracking processing thereof and demodulation processing of a navigation message including ephemeris data (satellite orbit information), and gives a pseudo-range observation and a Doppler frequency observation to a GPS positioning calculation module 32 and an integrated positioning calculation module 42.

0027The GPS positioning calculation module 32 calculates the navigation data such as a position, a velocity by a usual method based on the pseudo-range observation, the Doppler frequency observation, the ephemeris data and the like.

0028Based on the external support information including an output of the inertial sensor (gyroscope and acceleration sensor as needed), the above map information (map-match data) or information about the difference between the map position and a measured position (map-match data error), and the like as needed in addition to the pseudo-range observation and the Doppler frequency observation, the integrated positioning calculation module 42 estimates the position, position error, velocity, velocity error, error of the external support data of the inertial sensor or the like using a known Kalman filter. Then, the integrated positioning calculation module 42 gives the navigation data such as the position, velocity and the like to an output judgment module 43. Moreover, the estimated error of the external support data is fed back to a predetermined processing module as a correction amount.

0029The navigation data of the GPS positioning calculation module 32 is calculated independent of the integrated positioning calculation module 42. With this configuration, even if an abnormality caused due to the external support data occurs in the navigation data of the integrated positioning calculation module 42, the navigation data of the GPS positioning calculation module 32 is not affected by the abnormality of the external support data, and the navigation data of the GPS positioning calculation module 32 can be used to determine an abnormality of the navigation data of the integrated positioning calculation module 42. That is, in the output judgment module 43, all or any piece of the navigation data calculated by the GPS positioning calculation module 32 can be used as a comparative criterion to determine reliability of the output of the integrated positioning calculation module 42 output to a hardware/software 44 of the user.

0030Note that the GPS positioning calculation module 32 and the integrated positioning calculation module 42 are provided, along with the pseudo range and Doppler frequency, with the ephemeris data, which has no direct relation therewith in the first embodiment, thus is omitted in the figure.

0031Next, a method for determining various abnormalities by the output judgment module 43 is described with reference to <figref idref="f0003 f0004 f0005">Fig. 3 to Fig. 5</figref>.

0032<figref idref="f0003">Fig. 3</figref> is a flowchart showing a procedure of abnormality determination of the integrated positioning calculation module executed by the output judgment module 43.

0033The output judgment module 43 compares the output of the GPS positioning calculation module 32 and the output of the integrated positioning calculation module 42 (S11). In an example shown in <figref idref="f0003">Fig. 3</figref>, the reliability of the output data of the integrated positioning calculation module 42 is determined by the AND condition of the position determination, velocity determination and attitude determination of the navigation data (S12, S 13, S14).

0034Between the navigation data found respectively by the GPS positioning calculation module 32 and the integrated positioning calculation module 42, if a difference of the positions is equal to or more than a predetermined threshold value, the navigation data found by the GPS positioning calculation module 32 is switched to be output to the hardware/software 44 of the user (S12→S16). Similarly, if a difference of the velocities thereof is equal to or more than a predetermined threshold value, the navigation data found by the GPS positioning calculation module 32 is switched to be output to the hardware/software 44 of the user (S13→S16).

0035Further, if a difference between the attitude of the moving body found by the GPS positioning calculation module 32 and the attitude of the moving body found by the integrated positioning calculation module 42 is equal to or more than a predetermined threshold value, the navigation data found by the GPS positioning calculation module 32 is switched to be output to the hardware/software 44 of the user (S14→S16). Here, the attitude of the moving body is an orientation which the moving body is directed, and is found, for example, from a position vector at a certain time in a case of being found based on the position information, and is found using a ratio with respect to a horizontal velocity component in a case of being found based on the velocity information.

0036If the position, velocity and attitude are all less than the predetermined threshold values, the navigation data found by the integrated positioning calculation module 42 is output to the hardware/software 44 of the user.

0037Note that when the integrated positioning calculation module 42 resumes the positioning calculation, the processing of the integrated positioning calculation module is resumed using the position and velocity found by the GPS positioning calculation module 32 as initial values or the velocity thereof as an initial value.

0038The reliability of the output data of the integrated positioning calculation module 42 may be determined by a combination of the OR condition of the position determination, velocity determination and attitude determination of the navigation data, or by the AND or OR condition of any two of them and the AND or OR condition of the rest. For example, determination may be performed by a condition of (position AND velocity) OR attitude, or a condition of (position OR velocity) AND attitude.

0039<figref idref="f0004">Fig. 4</figref> is a flowchart showing a procedure of abnormality determination of the external support data executed by the output judgment module 43.

0040The output judgment module 43 executes the abnormality determination of the external support data using the output of the GPS positioning calculation module 32. For example, the abnormality of the signal of the gyroscope inertial sensor for obtaining the orientation information is determined by calculating an azimuth variation at a predetermined time interval of an azimuth angle calculated based on the velocity of the GPS positioning calculation module 32, at least during movement, and comparing the signal of the gyroscope inertial sensor with the azimuth angle variation amount as a reference (S21→S22). If a difference between them is less than a predetermined threshold value, the navigation data found by the integrated positioning calculation module 42 is output to the hardware/software 44 of the user (S22→S23). If the difference between them is equal to or more than the predetermined threshold value, the signal of the gyroscope inertial sensor is determined to be abnormal, and the navigation data found by the GPS positioning calculation module 32 is switched to be output to the hardware/software 44 of the user (S22→S24).

0041Note that a program may be defined in a case in which the azimuth variation is equal to or more than a certain value; if the signal of the gyroscope inertial sensor does not change, the output of the gyroscope inertial sensor is determined to be abnormal.

0042<figref idref="f0005">Fig. 5</figref> is a flowchart showing a procedure of abnormality determination of another external support data executed by the output judgment module 43.

0043The output judgment module 43 calculates a variation amount of the velocity at a predetermined time interval found by the GPS positioning calculation module 32, and, with the velocity variation amount being used as a reference value, compares the reference value with a signal of the acceleration sensor (S31→S32). If a difference between them is less than a predetermined threshold value, the navigation data found by the integrated positioning calculation module 42 is output to the hardware/software 44 of the user (S32→S33). If the difference between them is equal to or more than the predetermined value, the signal of the acceleration sensor is determined to be abnormal and the navigation data found by the GPS positioning calculation module 32 is output to the hardware/software 44 of the user (S32→S34).

0044Note that the program may be defined in a case in which the velocity variation is equal to or more than the predetermined threshold value set in advance; if the signal of the acceleration sensor does not change, the acceleration sensor is determined to be abnormal.

0045Similarly, in a case where a velocity sensor is used for the external support data, the abnormality of the signal of the velocity sensor is determined by comparing, with the velocity of the GPS positioning calculation module 32 being as a reference value, the reference value with the signal of the velocity sensor. Further, in a case where the velocity is equal to or more than a predetermined threshold value, if the signal of the velocity sensor does not change, the velocity sensor may be determined to be abnormal.

0046Further, the abnormality of the map position input information is determined by, with the position found by the GPS positioning calculation module 32 being used as a reference value, comparing the reference value with the map position input information.

0047Similarly, the abnormality of the error input information of the map position is determined by, with the velocity found by the GPS positioning calculation module 32 or the position variation at a predetermined time interval being as a reference value, comparing the reference value with the error input information of the map position.

0048The above map position input information is specifically the map position data of, for example, the satellite navigation/dead-reckoning navigation integrated device generated in a car navigation system, and the map position is input as latitude and longitude data.

0049Additionally, the error input information of the map position is specifically information of a difference between, for example, data of the car navigation system or other position measurement devices and the map position data, and are input as position error information.

0050Note that in any of the above abnormality determinations, the abnormality of the input data may be determined depending on not only whether or not the difference between the reference value and a value of the target to be determined about abnormality thereof exceeds a predetermined threshold value, but also whether or not the number of cases where the difference exceeds the predetermined threshold value reaches a predetermined number.

SECOND EMBODIMENT

0051<figref idref="f0006">Fig. 6</figref> is a block diagram showing a configuration of a satellite navigation/dead-reckoning navigation integrated positioning device according to a second embodiment of the invention.

0052This embodiment is different from the satellite navigation/dead-reckoning navigation integrated positioning device shown in <figref idref="f0002">Fig. 2</figref> of the first embodiment in the configuration of the integrated positioning calculation module 53 and a relationship between the integrated positioning calculation module 53 and the GPS positioning calculation module 32.

0053A satellite position correction value calculation module 51 in the GPS positioning calculation module 32 calculates values concerning satellite position and correction values including a position and a velocity of a satellite, a satellite time correction value, an ionospheric correction value, a tropospheric correction value and the like from information, such as the ephemeris and the positioning results obtained by the positioning calculation module 52. The values themselves have configurations similar to the general GPS receiver. The values calculated by the satellite position/correction value calculation module 51 are used in both the positioning calculation module 52 and the integrated positioning calculation module 53.

0054In this way, the satellite position/correction amount calculation module 51 is commonly used, and thus, the calculation processing load on the satellite navigation/dead-reckoning navigation integrated positioning device can entirely be reduced. Therefore, processing can be performed with a low velocity CPU, leading to low cost correspondingly.

0055Note that in the embodiments shown above, the example using GPS for the satellite navigation positioning is shown, but it is similarly applicable to a case of using another satellite navigation positioning system.

BRIEF DESCRIPTION OF THE NUMERALS

0056<ul id="ul0004" list-style="none" compact="compact"><li>30... GPS Receiving Circuit; 31... Tracking Processing Module; 32... GPS Positioning Calculation Module; 42... Integrated Positioning Calculation Module; 43... Output Judgment Module; 51... Satellite Position Correction Value Calculation Module; 52... Positioning Calculation Module; 53... Integrated Positioning Calculation Module; and 100, 101... Satellite Navigation/Dead-Reckoning Navigation Integrated Positioning Device.</li></ul>