JP2009168614A - On-vehicle navigation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an "on-vehicle navigation device" for accurately calculating one's own vehicle position at a point where a GPS signal cannot be received by calculating accurate vehicle speed without using a vehicle speed pulse. <P>SOLUTION: The correlation (speed ratio K) between vehicle speed (first vehicle speed (a) calculated based on the GPS signal immediately before a GPS non-receiving period) and a video speed (video speed (b) calculated based on photographed video of an on-vehicle camera at the start time of the GPS non-receiving period) is considered to be kept even in the GPS non-receiving period. By multiplying the speed ratio K by a video speed (b') in the GPS non-receiving period, a second vehicle speed (a') is calculated as a false first vehicle speed, and the second vehicle speed (a') is used for autonomous navigation. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an on-vehicle navigation device, and more particularly to an on-vehicle navigation device suitable for calculating the position of the host vehicle.

  Conventionally, in an in-vehicle navigation device, it has been important to calculate an accurate own vehicle position in order to reliably guide the route of the own vehicle along the route to the destination (route guidance).

  As a calculation method of the own vehicle position in such an in-vehicle navigation device, two calculation methods of satellite navigation and autonomous navigation have been known.

  In satellite navigation, a GPS signal including information on orbits and times transmitted from GPS satellites is received, and the vehicle position is calculated as three-dimensional absolute coordinates based on the received GPS signals. Yes.

  On the other hand, in autonomous navigation, the azimuth sensor such as a gyro sensor calculates the azimuth of the host vehicle, calculates the moving distance of the host vehicle by a vehicle speed pulse, and then calculates one based on the calculated azimuth and moving distance. The current vehicle position as a change from the previous calculated position (vehicle position) is calculated as a relative position.

JP 2005-291732 A JP 2006-317287 A JP 2007-240380 A

  By the way, in recent years, an in-vehicle navigation device that is detachably mounted on a vehicle called an in-vehicle portable navigation device (mainly the upper part of the instrument panel or the front mirror) is improved in GPS accuracy and can be taken out and attached to the outside of the vehicle. Is becoming popular for reasons such as simplicity.

  This type of in-vehicle portable navigation device has a product specification in which the number of wirings is reduced as much as possible in order to easily, accurately and stably attach to the vehicle.

  For this reason, in the in-vehicle portable navigation device, the vehicle position is calculated only by satellite navigation using a GPS signal without inputting the vehicle speed pulse which is essential in the normal in-vehicle navigation device. It was.

  Here, the GPS signal originally included a signal that deteriorated the accuracy. However, since this signal was canceled in May 2000, the position of the vehicle was sufficient even with the GPS signal alone. It became possible to give accuracy.

  However, in the valleys of high-rise buildings, in tunnels, and under elevated roads, GPS signals cannot be received, and the vehicle position cannot be calculated.

  Therefore, in order to solve such a problem, countermeasures using the video captured by the in-vehicle camera have been taken so far.

  As an example of the countermeasure, a white line photographed image on a road by an in-vehicle camera is recognized, and the white line photographed image is a speed at which the captured image of the white line flows (displaces) in a direction opposite to the traveling direction of the host vehicle. There has been a technology for obtaining the video speed of a captured video, converting the obtained video speed into a vehicle speed, and using it for autonomous navigation. However, such countermeasures cannot be used when a white line is not drawn on the road, and image processing for white line recognition is costly. In addition, when determining the vehicle speed based only on the video speed of the captured video of the scenery, not limited to the white line, it is difficult to specify an appropriate vehicle speed because the video speed also varies depending on the distance from the in-vehicle camera to the scenery (shooting target) Met.

  Therefore, conventionally, no effective solution has been proposed for the problem of appropriately calculating the vehicle position in the in-vehicle portable navigation device.

  Accordingly, the present invention has been made in view of the above points, and by calculating an accurate vehicle speed without using a vehicle speed pulse, the vehicle position at a point where GPS signals cannot be received is calculated with high accuracy. Therefore, an object of the present invention is to provide a vehicle-mounted navigation device that can reliably perform route guidance.

  In order to achieve the above-described object, an in-vehicle navigation device according to the present invention is an in-vehicle navigation device that does not use a vehicle speed pulse for calculating the position of the host vehicle, and is used for shooting a predetermined shooting area around the host vehicle. A camera, GPS receiving means capable of receiving GPS signals transmitted from GPS satellites, satellite navigation means for calculating the vehicle position based on the GPS signals received by the GPS receiving means, and satellite navigation First vehicle speed calculating means for calculating a first vehicle speed based on the time change of the host vehicle position calculated by the means, and the captured video based on the time change of the captured video of the in-vehicle camera. It becomes impossible to receive the GPS signal by the video speed calculating means for calculating the video speed, which is the speed flowing in the direction opposite to the traveling direction, and the GPS receiving means. A speed ratio calculating means for calculating a speed ratio that is a value obtained by dividing the first vehicle speed immediately before the time by the video speed at the time, and the speed ratio calculated by the speed ratio calculating means. In the GPS unreceivable period, which is a period between the time when reception of the GPS signal becomes impossible and the time when reception of the GPS signal recovers. Second vehicle speed calculation means for calculating a second vehicle speed by multiplying the video speed by the speed ratio stored by the speed ratio storage means; and the second vehicle speed calculation means calculated by the second vehicle speed calculation means. An autonomous navigation means for calculating the position of the vehicle during the GPS unreceivable period by using the vehicle speed is provided.

  According to such a configuration, the vehicle speed (the first vehicle speed calculated based on the GPS signal immediately before the GPS incapable period) and the video speed (the captured video of the in-vehicle camera at the start of the GPS incapable period). By assuming that the correlation (speed ratio) with the video speed calculated based on (2) is maintained even during the GPS non-receivable period, the speed ratio is multiplied by the video speed within the GPS non-receivable period. The second vehicle speed can be calculated as the pseudo first vehicle speed, and the second vehicle speed can be used for autonomous navigation. As a result, by calculating an accurate vehicle speed that can be substituted for the vehicle speed pulse without using the vehicle speed pulse, the position of the vehicle at a point where GPS signals cannot be received can be calculated with high accuracy. Can be performed reliably.

  In addition, the speed ratio calculation unit may determine that the change amount is the threshold change amount when the change amount of the video speed is equal to or greater than the threshold change amount in the GPS non-reception period after the start of the GPS non-reception period. The second vehicle speed formed immediately before the time point when the second vehicle speed is divided by the video speed at the time point is calculated to calculate a second speed ratio, and the speed ratio storage unit is configured to calculate the speed ratio. When the second speed ratio is calculated by the means, the second speed ratio is configured to be stored, and the second vehicle speed calculating means is configured to store the second speed ratio by the speed ratio storage means. When the ratio is stored, the reception of the GPS signal is recovered from the time when the change amount in the GPS incapable period becomes equal to or greater than the threshold change amount, or the change amount is again equal to or greater than the threshold change amount. In a part of the period up to the point in time, the second speed ratio is obtained by multiplying the video speed in the part of the period by the second speed ratio stored by the speed ratio storage means. The second vehicle speed is calculated using the second speed ratio by the second vehicle speed calculation means, and the second vehicle speed calculation means is configured to calculate the second vehicle speed. In this case, it is preferable that the vehicle position in the partial period is calculated by using the second vehicle speed.

  According to such a configuration, when the video speed shows a large amount of change at the start of a part of the GPS unreceivable period, the travel environment is not the actual vehicle speed but the change. After determining that the distance between the in-vehicle camera and the object to be imaged has changed, the vehicle speed (the second vehicle speed immediately before the part of the period) and the video speed during a part of the period when the driving environment has changed. By assuming that a new correlation (second speed ratio) with (video speed at the start of some period) is maintained and multiplying the second speed ratio by the video speed during some period The second vehicle speed can be calculated by a new calculation method, and this second vehicle speed can be used for autonomous navigation. Thereby, even when the distance between the in-vehicle camera and the object to be imaged changes within the GPS unreceivable period, the second vehicle speed that can be substituted for the vehicle speed pulse following this change can be calculated appropriately. An accurate own vehicle position can be calculated more stably.

  Furthermore, the speed ratio calculating means changes the threshold value at the Nth time (where N is an arbitrary natural number equal to or greater than 1) during the GPS unreceivable period after the start of the GPS unreceivable period. When the amount exceeds the amount, the second vehicle speed immediately before the time point when the amount of change becomes the threshold amount of change for the Nth time is divided by the video speed at the time point, thereby The speed ratio storage means is calculated for the Nth time when the Nth second speed ratio is calculated by the speed ratio calculation means. The second vehicle speed calculation means is configured to store the second speed ratio calculated by the N-th time by the speed ratio storage means. GPS unreceivable period A part of the Nth time from when the change amount becomes the threshold change amount or more at the Nth time until the reception of the GPS signal is recovered or the change amount becomes the threshold change amount or more again. In the period, the video speed in the Nth partial period is calculated by multiplying the second speed ratio calculated in the Nth time stored in the speed ratio storage unit by the Nth time. The second vehicle speed is calculated using the second speed ratio, and the autonomous navigation means uses the second speed ratio calculated by the second time by the second vehicle speed calculation means. When the second vehicle speed is calculated, it is preferable that the second vehicle speed is used to calculate the vehicle position in the Nth partial period. .

  According to such a configuration, even when the distance between the in-vehicle camera and the object to be imaged changes a plurality of times after the start of the GPS non-receivable period, the vehicle speed pulse is replaced by following these changes. The possible new second vehicle speed can be calculated sequentially, and the vehicle position accuracy can be secured more stably.

  The speed ratio calculation means further includes the second speed ratio when the calculation result of the acceleration sensor is equal to or less than a threshold acceleration at the time when the change amount is equal to or greater than the threshold change amount. It is preferable to be configured to calculate.

  According to such a configuration, the second speed ratio is calculated after confirming that the actual vehicle speed has not greatly changed based on the calculation result of the acceleration sensor. Can be calculated more appropriately, and the vehicle position can be calculated with higher accuracy.

  In addition, the speed ratio calculation unit is configured such that the change amount is equal to or greater than the threshold change amount again from a first time point when the change amount is equal to or greater than the threshold change amount in the GPS unreceivable period after the start of the GPS unreceivable period. And when the detected time is less than a threshold time, the amount of change in the video speed at the second time is ignored and the second time is detected. It is preferable that the second speed ratio is not calculated at the time.

  According to such a configuration, for example, when an object exists in the tunnel at a position closer to the vehicle side than the upper wall surface of the tunnel, such as an air conditioning fan or pipe, When shooting, the video speed may temporarily show a large amount of change, but by ignoring such a short-time change, an accurate second vehicle speed suitable for the driving environment during the GPS unreceivable period is calculated. This can further improve the vehicle position accuracy.

  Further, the video speed calculation means divides the video image taken by the in-vehicle camera into a plurality of video areas, and calculates the video speed for each video area based on the temporal change of the video for each divided video area. The predetermined number of the video areas such that the change amount of the video speed for each video area is equal to or greater than the threshold change amount at an arbitrary time point within the GPS non-reception period after the start of the GPS non-reception period. Is less than the average value of the video speed for each video area in the other video areas excluding the video area such that the amount of change in the video speed for each video area is equal to or greater than the threshold change amount. It is preferable that the video speed used for calculation of the second vehicle speed at the arbitrary time point is set to be the same.

  According to such a configuration, for example, the video image of the fan or pipe in the tunnel has a small area ratio with respect to the entire video image taken by the in-vehicle camera. When there are a small number of video areas showing a large change, the video speed used for calculating the second speed is obtained based on the video speed of each video area with respect to other video areas ignoring these video areas. Therefore, it is possible to calculate the accurate second vehicle speed that is suitable for the driving environment during the GPS unreceivable period, and to further improve the vehicle position accuracy.

  Furthermore, it is preferable that the in-vehicle camera is arranged so as to be able to photograph the upper side of the host vehicle.

  According to such a configuration, when the upper side of the host vehicle is shielded during the GPS unreceivable period, the video speed is calculated based on the shot video of the shooting target above the host vehicle, 2 can be used for calculation of the vehicle speed of 2, so that it is advantageous for calculation of the position of the vehicle when traveling in such a GPS unreceivable period where the upper part is shielded.

  Moreover, it is preferable that the GPS incapable period is a period in which the host vehicle is traveling in a tunnel or under an elevated route.

  According to such a configuration, the video speed is calculated on the basis of the captured video of the upper wall surface of the tunnel or the bottom surface of the elevated road, and this is used to calculate the second vehicle speed during the period of traveling in the tunnel or under the elevated road. Since it can be used for calculation, it is advantageous for calculating the position of the vehicle when traveling in a tunnel or under an elevated route.

  Further, the in-vehicle camera is arranged so as to be able to photograph the left side and the right side of the host vehicle, and the video speed calculation means is a left side calculated based on a time change of the left side captured video. And an average value of the right-side video speed calculated based on the temporal change of the right-side captured video is used as the video speed used for the calculation of the second vehicle speed. It is preferable.

  According to such a configuration, when the left side and the right side of the host vehicle are shielded during the GPS incapable period, the shot image of the shooting target on the left side of the host vehicle and the shooting target of the right side are displayed. Since the video speed can be calculated as an average value based on both the captured video and this can be used for the calculation of the second vehicle speed, it is possible to travel during such GPS unreceivable periods where the left side and the right side are shielded. This is advantageous for the calculation of the position of the host vehicle. Especially when driving on the road, the distance between the in-vehicle camera and the object to be photographed on both sides changes due to lane changes, but if the average value of the image speed on both sides is taken, the image speed can be calculated appropriately. Can do.

  Furthermore, it is preferable that the GPS unreceivable period is a period in which the host vehicle is traveling in a valley of a high-rise building.

  According to such a configuration, the video speed can be calculated based on the captured video of the building, and this can be used to calculate the second vehicle speed during the period when the vehicle is traveling in the valley of the building. This is advantageous for calculating the position of the vehicle when traveling in the valley.

  Moreover, it is preferable that the said vehicle-mounted camera is directly mounted in the vehicle-mounted navigation apparatus main body.

  And according to such a structure, a vehicle-mounted navigation apparatus main body and a vehicle-mounted camera can be handled integrally, and the attachment with respect to the own vehicle can be performed still more easily.

  According to the present invention, by calculating an accurate vehicle speed without using a vehicle speed pulse, it is possible to calculate the position of the vehicle at a point where GPS signals cannot be received with high accuracy, and as a result, route guidance can be reliably performed. It can be carried out. Further, complicated image processing such as white line recognition is not required, and the vehicle speed can be calculated based on the video speed, so that the cost can be reduced.

  Hereinafter, an embodiment of an in-vehicle navigation device according to the present invention will be described with reference to FIGS. 1 to 5.

  The vehicle-mounted navigation device according to the present embodiment is a vehicle-mounted portable navigation device that is detachably disposed on the host vehicle, and from the viewpoint of reducing the number of wires and facilitating attachment / detachment to the host vehicle. No pulse is input, and the vehicle speed pulse is not used for calculating the vehicle position.

  FIG. 1 shows an in-vehicle navigation device 1 according to this embodiment.

  As shown in FIG. 1, an in-vehicle navigation device 1 according to this embodiment is roughly divided into a navigation main unit 2 that performs main processing and control for navigation, and an in-vehicle camera connected to the navigation main unit 2. 3, a GPS receiver 5 as a GPS receiving means, a storage device 6, an input operation unit 7, a display 8, and a speaker 9.

  The in-vehicle camera 3 captures a predetermined capturing area around the host vehicle. The in-vehicle camera 3 may be a camera that includes an ultra-wide-angle lens such as a fish-eye lens and forms an image to be photographed on an imaging surface of a solid-state imaging device such as a CCD or a CMOS.

  The in-vehicle camera 3 is preferably directly mounted on the apparatus main body of the in-vehicle navigation apparatus 1 without using a long cable or the like (unitized with the apparatus main body). In this way, when the apparatus main body of the in-vehicle navigation device 1 is attached to and detached from the own vehicle, the in-vehicle camera 3 and the apparatus main body can be handled integrally. Detachment becomes easier.

  The GPS receiver 5 receives a GPS signal including information on the orbit and the time from the GPS satellite 11 and inputs the received GPS signal to the navigation main unit 2.

  The storage device 6 is equipped with a storage medium in which map data is stored. The storage device 6 may be, for example, a DVD drive on which a DVD as a storage medium is mounted, or a hard disk drive.

  Further, the input operation unit 7 may be, for example, a remote controller, a linear encoder, a rotary encoder, or a touch panel of the display 8.

  The navigation main unit 2 will be described in detail. The navigation main unit 2 has a navigation CPU 12 as a main control unit.

  The in-vehicle camera 3 is connected to the navigation CPU 12 via a system bus 15 and a camera interface (I / F) 14, and a video image taken by the in-vehicle camera 3 is sent to the navigation CPU 12 via the camera interface 14 and the system bus 15. It is designed to be entered.

  A GPS receiver 5 is connected to the navigation CPU 12, and a GPS signal from the GPS receiver 5 is input to the navigation CPU 12.

  Further, a decoder 16 is connected to the navigation CPU 12 via a system bus 15, and a storage device 6 is connected to the decoder 16. The decoder 16 decodes the map data read by the storage device 6 in accordance with a read request from the navigation CPU 12 and inputs the decoded map data to the navigation CPU 12.

  Furthermore, a display 8 is connected to the navigation CPU 12 via a system bus 15 and an image interface (I / F) 17.

  An input operation unit 7 is connected to the navigation CPU 12 via a system bus 15 and a user interface (I / F) 19.

  Furthermore, a speaker 9 is connected to the navigation CPU 12 via an audio interface (I / F) 18.

  Furthermore, a memory 20 is connected to the navigation CPU 12 via a system bus 15.

  The navigation CPU 12 is connected to a direction sensor 21 formed of a gyro sensor or the like, and the direction of the host vehicle detected by the direction sensor 21 is input to the navigation CPU 12.

  The navigation CPU 12 will be described in more detail. The navigation CPU 12 has a satellite navigation unit 22 as satellite navigation means. The satellite navigation unit 22 is based on the GPS signal received and input by the GPS receiver 5. The own vehicle position (hereinafter referred to as satellite navigation position) is calculated.

  The navigation CPU 12 has a satellite navigation time vehicle speed calculation unit 23 as first vehicle speed calculation means. The satellite navigation time vehicle speed calculation unit 23 calculates the time of the satellite navigation position calculated by the satellite navigation unit 22. Based on the change, the vehicle speed during satellite navigation as the first vehicle speed is calculated.

  Further, the navigation CPU 12 includes a video speed calculation unit 24 as a video speed calculation unit. The video speed calculation unit 24 acquires a captured video of the in-vehicle camera 3 and changes the time of the acquired captured video. Based on this, a video speed that is a speed (relative speed) at which the captured video flows in a direction opposite to the traveling direction of the host vehicle is calculated.

  Furthermore, the navigation CPU 12 has a speed ratio calculation unit 25 as speed ratio calculation means. This speed ratio calculation unit 25 is the satellite navigation hour vehicle speed (hereinafter referred to as “the satellite navigation hour vehicle speed”) calculated last by the satellite navigation hour vehicle speed calculation unit 23 immediately before the GPS signal reception by the GPS receiver 5 becomes impossible. A speed ratio, which is a value obtained by dividing a vehicle speed immediately before GPS reception impossible) by a video speed at which the GPS signal cannot be received (hereinafter referred to as a GPS speed when GPS reception cannot be started), is calculated. It has become. If the vehicle speed immediately before GPS reception is impossible is a [km / h], the video speed at the start of GPS reception is b [km / h], and the speed ratio is K, the relational expression K = a / b is established. To do.

  The speed ratio calculation unit 25 stores the calculated speed ratio in the memory 20 as speed ratio storage means.

  The navigation CPU 12 has an autonomous navigation vehicle speed calculation unit 27 as second vehicle speed calculation means. The autonomous navigation vehicle speed calculation unit 27 is configured to display a video speed (hereinafter referred to as a video speed) during this period in a GPS unreceivable period, which is a period between the time when reception of a GPS signal becomes impossible and the time when reception of GPS signals recovers. The vehicle speed for autonomous navigation as the second vehicle speed is calculated by multiplying the speed ratio stored in the memory 20 by the image speed during GPS reception impossible). Note that the relationship of a ′ = b ′ × K is assumed, where b ′ [km / h] is the video speed when GPS cannot be received, a ′ [km / h] is the vehicle speed for autonomous navigation, and K is the speed ratio. The formula holds.

  Furthermore, the navigation CPU 12 has an autonomous navigation unit 28 as autonomous navigation means. This autonomous navigation unit 28 is detected by the autonomous navigation vehicle speed calculated by the autonomous navigation vehicle speed calculation unit 27 and the direction sensor 21. By using the determined direction, the vehicle position (hereinafter referred to as the autonomous navigation position) in the GPS unreceivable period is calculated. That is, in the present embodiment, autonomous navigation is performed using the vehicle speed for autonomous navigation that replaces the vehicle speed pulse.

  According to such a configuration, it is assumed that the correlation (speed ratio) between the vehicle speed (vehicle speed immediately before GPS reception is impossible) and the video speed (video speed when GPS reception cannot be started) is maintained in the GPS non-reception period. Therefore, by multiplying the speed ratio by the video speed during the GPS unreceivable period, the vehicle speed for autonomous navigation was calculated as the pseudo vehicle speed during satellite navigation, and this vehicle speed for autonomous navigation was used for autonomous navigation. By calculating an accurate vehicle speed that can be substituted for a vehicle speed pulse without using a pulse, the autonomous navigation position at a point where GPS signals cannot be received can be calculated with high accuracy.

  In addition, as a GPS reception impossibility period, the period when the own vehicle is drive | working the inside of a tunnel, under an overpass or the valley of a high-rise building etc. can be considered, for example.

  Furthermore, in a more preferred embodiment, the amount of change in video speed (hereinafter referred to as video) during the GPS unreceivable period (hereinafter referred to as the non-receivable period after start) after the start of the GPS unreceivable period (that is, excluding the start time). When the speed change amount is equal to or greater than the threshold change amount, the speed ratio calculation unit 25 calculates the corrected vehicle speed ratio as the second vehicle speed ratio. The corrected vehicle speed ratio is the vehicle speed for autonomous navigation last calculated by the autonomous navigation vehicle speed calculation unit 27 immediately before the time point when the video speed change amount is equal to or greater than the threshold change amount (hereinafter referred to as the vehicle speed immediately before the threshold change). Is divided by the video speed at which the video speed change amount is equal to or greater than the threshold change amount (hereinafter referred to as the threshold-change video speed).

  When the corrected vehicle speed ratio is calculated in this way, the memory 20 stores the corrected speed ratio calculated by the speed ratio calculation unit 25.

  In this case, the autonomous navigation vehicle speed calculation unit 27 recovers the reception of the GPS signal or the video speed change amount from the time when the video speed change amount in the incapable reception period after the start becomes equal to or greater than the threshold change amount. Multiplying the video speed in the period after the threshold change by the correction speed ratio stored in the memory 20 during a part of the period until the time when the threshold change amount is again exceeded (hereinafter referred to as the period after the threshold change). Thus, the vehicle speed for autonomous navigation using the corrected speed ratio is calculated.

  Further, in this case, the autonomous navigation unit 28 calculates the autonomous navigation position in the period after the threshold change by using the autonomous navigation vehicle speed calculated using the corrected speed ratio.

  According to such a configuration, when the video speed shows a large amount of change at the start of the period after the threshold change, the actual vehicle speed does not change, but the traveling environment (for example, the height of the upper wall of the tunnel). ) Changes to determine that the distance between the in-vehicle camera 3 and the object to be imaged has changed, and the correlation between the vehicle speed and the video speed can be corrected from the initial speed ratio to the corrected speed ratio. Then, it is assumed that the corrected speed ratio is maintained in the period after the threshold change, and the vehicle speed for autonomous navigation can be calculated by a new calculation method by multiplying the corrected speed ratio by the video speed in the period after the threshold change. . As a result, even when the distance between the in-vehicle camera 3 and the object to be imaged changes within the GPS unreceivable period, it is possible to appropriately calculate the vehicle speed for autonomous navigation that can replace the vehicle speed pulse following this change, A highly accurate vehicle position can be calculated more stably.

  Further, as a more preferable embodiment, when the video speed change amount is N times (where N is an arbitrary natural number equal to or greater than 1) in the non-reception period after the start, The calculation unit 25 calculates the Nth corrected vehicle speed ratio as the Nth second vehicle speed ratio. Here, the N-th corrected vehicle speed ratio refers to the vehicle speed for autonomous navigation immediately before the video speed change amount becomes equal to or greater than the threshold change amount for the Nth time (hereinafter referred to as the vehicle speed immediately before the Nth threshold change). It has a value divided by the video speed when the video speed change amount is equal to or greater than the threshold change amount for the Nth time (hereinafter referred to as the Nth threshold value change video speed).

  In this way, when the Nth corrected vehicle speed ratio is calculated, the memory 20 stores the Nth corrected speed ratio calculated by the speed ratio calculation unit 25.

  Further, in this case, the autonomous navigation vehicle speed calculation unit 27 recovers the reception of the GPS signal or changes in the video speed from the time when the video speed change amount in the GPS incapable period becomes the threshold change amount or more for the Nth time. In a part of the period until the time when the amount becomes equal to or more than the threshold change amount again (hereinafter referred to as the Nth threshold change period or later), the video speed in the period after the Nth threshold change is stored in the memory 20. By multiplying the Nth corrected speed ratio, the vehicle speed for the Nth autonomous navigation using the Nth corrected speed ratio is calculated.

  Further, in this case, the autonomous navigation unit 28 calculates the autonomous navigation position in the period after the Nth threshold change by using the calculated vehicle speed for the Nth autonomous navigation.

  And according to such a configuration, even when the distance between the in-vehicle camera and the object to be imaged has changed several times within the incapable reception period after the start, the autonomous navigation can follow these changes and substitute for the vehicle speed pulse. The vehicle speed can be calculated sequentially, and the vehicle position accuracy can be secured more stably.

  Furthermore, as a more preferable embodiment, after the acceleration sensor is arranged in the navigation main unit 2, the calculation result of the acceleration sensor at the time when the video speed change amount within the reception impossible period after the start becomes equal to or larger than the threshold change amount. Is equal to or less than the threshold acceleration, the speed ratio calculation unit 25 calculates the corrected speed ratio.

  According to such a configuration, it is possible to calculate the corrected speed ratio after confirming that the actual vehicle speed has not greatly changed based on the calculation result of the acceleration sensor, so that the vehicle speed for autonomous navigation can be further increased. The vehicle position can be calculated appropriately, and the vehicle position can be calculated with higher accuracy.

  In a more preferred embodiment, the speed ratio calculation unit 25 sets the video speed change amount to be equal to or greater than the threshold change amount again from the first time point when the video speed change amount is equal to or greater than the threshold change amount in the non-reception period after start. When the time until the second time point is detected and the detected time is less than the threshold time, the change rate of the video speed at the second time point is ignored and the corrected speed ratio at the second time point is ignored. Do not calculate.

  In such a configuration, for example, the in-vehicle camera 3 is disposed so as to be able to photograph the upper side of the host vehicle, and the captured image of the upper wall surface of the tunnel by the in-vehicle camera 3 during the traveling period in the tunnel as the GPS incapable period. This is effective when the video speed of is used to calculate the vehicle speed for autonomous navigation. In other words, when an object is present in the tunnel at a position closer to the vehicle side than the upper wall surface of the tunnel, such as a fan or pipe for air conditioning, the image speed can be increased by temporarily shooting such an object. May show a large amount of change. However, such a change in the image speed occurs only in a short time when the host vehicle passes through the fan or pipe, and is caused by a large change in the driving environment such as a change in the height of the upper wall surface in the tunnel. It is not what I did. Therefore, by ignoring such a short-time change, it is possible to calculate an accurate vehicle speed for autonomous navigation suitable for the driving environment (the height of the upper wall surface of the tunnel) during the GPS incapable period, Can be further improved.

  Furthermore, as a more preferable embodiment, the video speed calculation unit 24 divides a video image taken by the in-vehicle camera 3 into a plurality of video regions (for example, 25 divisions), and changes the time of the video for each divided video region. Based on this, the video speed for each video area is calculated. If the number of video areas in which the amount of change in the video speed for each video area is equal to or greater than the threshold change amount at an arbitrary time point during the reception incapable period after the start is less than the predetermined number, the predetermined number is satisfied. The average value of the video speed for each video area for other video areas excluding the non-existing video area is set as the video speed used for calculating the vehicle speed for autonomous navigation at the arbitrary time point.

  Such a configuration is also suitable for the calculation of the vehicle speed for autonomous navigation in traveling in a tunnel as described above, for example. That is, the area ratio of the captured image of the fan or pipe in the tunnel is small compared to the entire captured image of the in-vehicle camera 3. Therefore, by using this fact, when there are a small number of video areas in which the video speed for each video area has changed significantly, these small video areas should not contribute to the calculation of the vehicle speed for autonomous navigation. Autonomous navigation vehicle speed can be calculated based on the video speed of each video area for other video areas that are considered to have been shot of the fan or pipe and ignored. it can. As a result, it is possible to calculate an accurate vehicle speed for autonomous navigation that is suitable for the driving environment during the GPS unreceivable period, and to further improve the vehicle position accuracy.

  Furthermore, as a more preferable embodiment, a plurality of in-vehicle cameras 3 are arranged so as to be able to photograph the left side and the right side of the host vehicle, and the video speed calculation unit 24 changes the time of the captured video on the left side. Calculate the video speed used to calculate the vehicle speed for autonomous navigation, using the average value of the video speed on the left side calculated based on the left side and the video speed on the right side calculated based on the temporal change of the captured video on the right side. Configure to result.

  According to such a configuration, for example, when the left side and the right side of the host vehicle are shielded during the GPS reception-disabled period, such as when traveling in a valley of a building, For example, the video speed is calculated as an average value based on both the video image taken on the left side wall of the building and the video image taken on the right side (for example, the right side wall of the building), and this is used for autonomous navigation. It can be used for calculation of vehicle speed. Here, when traveling on the road, for example, the distance between the in-vehicle camera 3 and the object to be photographed on the left side of the host vehicle may naturally change due to a lane change. If the average value of the video speeds is taken, an appropriate video speed can be calculated in consideration of the actual situation of such traveling.

  In addition to the above configuration, the vehicle-mounted navigation device 1 according to the present embodiment has various configurations for navigation.

  That is, the navigation CPU 12 has a map matching processing unit 29, and the map matching processing unit 12 has an autonomous navigation position calculated by the autonomous navigation unit 28 and a radio navigation position calculated by the satellite navigation unit 22. If it is not on the corresponding road on the map, map matching processing is performed to correct the vehicle position on the corresponding road on the map. This map matching process is performed by reading map data from the storage device 6 and using the read map data. When the map matching processing by the map matching processing unit 29 is appropriately performed, the own vehicle position after the map matching processing becomes the final calculation result of the own vehicle position.

  The navigation CPU 12 has a map drawing unit 31. The map drawing unit 31 generates a map around the vehicle position by using the map data read from the storage device 6, and is generated. The map is displayed on the display 8 via the system bus 15 and the image interface 17.

  Further, the navigation CPU 12 has a vehicle position drawing unit 32, which is displayed on a map around the vehicle position based on the map matching processing result by the map matching processing unit 29. The vehicle position mark indicating the vehicle position is displayed.

  Furthermore, the navigation CPU 12 has a destination setting unit 33, which uses the input operation unit 7 for the destination setting operation screen displayed on the display 8 by the navigation CPU 12. A destination is set according to the user's input operation.

  The navigation CPU 12 includes a route search unit 35. The route search unit 35 reads the route calculation for searching for a recommended route from the vehicle position to the destination, and is read from the storage device 6. It is supposed to be done using.

  Further, the navigation CPU 12 includes a route guidance unit 36 that guides the vehicle to the destination (route guidance) along the recommended route searched by the route search unit 35. It has become. This route guidance may be based on display of a guidance image (for example, a superimposed display image of a recommended route on a map or an enlarged view of an intersection) on the display 8, or guidance voice from the speaker 9 (for example, (Intersection right / left turn guidance) may be output, or both of these displays and audio may be used.

Next, more specific operation examples of the vehicle-mounted navigation device 1 according to this embodiment will be described separately.
(First operation example)
As a first operation example, as shown in FIG. 2, an in-vehicle camera 3 that photographs the upper side of the own vehicle is mounted, and the in-vehicle navigation device 1 attached to, for example, an upper panel of the own vehicle, An operation when the vehicle enters the tunnel will be described.

Incidentally, in the initial state (time t ₀ in FIG. _2), the vehicle is assumed to be traveling the front of the entrance of the tunnel. In the initial state, it is assumed that the calculation of the satellite navigation position by the satellite navigation unit 22 and the calculation of the video speed by the video speed calculation unit 24 are continuously performed as the host vehicle travels.

When the host vehicle enters the tunnel from the initial state, the GPS receiver 5 cannot receive the GPS signal, and the satellite navigation position cannot be calculated. As a result, the GPS unreceivable period starts (time t ₁ in FIG. 2).

  At this time, as shown in FIG. 2, the speed ratio calculation unit 25 divides the vehicle speed a [km / h] immediately before GPS reception impossible shown in FIG. 2 by the video speed b [km / h] at the start of GPS reception failure. Thus, the speed ratio K (= a / b) is calculated, and the calculated speed ratio K is stored in the memory 20. Note that, as shown in FIG. 2, it is considered that the vehicle speeds coincide with each other immediately before and immediately after the start of the GPS unreceivable period.

  Here, a specific calculation method of the video speed of the video captured by the in-vehicle camera 3 such as the GPS reception incapable start video speed b will be described.

  In calculating the video speed, first, as shown in FIG. 3A, image data at time (t) and image data at time (t + 1) are prepared as image data indicating a video image taken by the in-vehicle camera 3. To do. Both the image data are composed of a plurality of dots arranged vertically and horizontally, and the numbers of dots in both the length and width are the same. In FIG. 3 (a), in order to make the following explanation easy to understand, as a simple model, one dot row in which 10 dots are arranged vertically is arranged in 10 rows in the horizontal direction. Although 10 × 10 dot image data is shown, the actual image data is composed of a larger number of dots. In FIG. 3A, the shading in each dot represents the shading of the image. Further, in FIG. 3A, the traveling direction of the host vehicle corresponds to the right direction in FIG.

  Next, as shown in FIG. 3B, the number of dot rows is cut from the image data at time (t) toward the running direction from the end portion on the opposite side in the running direction, and the image data at time (t + 1). To determine how many dot rows are cut from the end in the running direction toward the opposite direction in the running direction, the image data match each other. Specifically, the number of cuts in a dot row is sequentially increased from 0 to n rows (n is usually about half the screen width), and when dot row cuts of each cut number are performed, Each time, the correlation coefficient is calculated from the data sequence of the image data after the dot sequence is cut.

Here, as shown in FIG. 3B, the data sequence of the image data at the time (t) used for calculating the correlation coefficient is the n columns on the left side from the state of FIG. 3A (FIG. 3B 1 row data {x _i } (i) in which each dot of the image data at time (t) after the dot row cut of 2 rows in () is sequentially connected from the _first dot x _{1 in the} vertical direction. = 1, 2,..., K) (where k is the total number of dots in the image data after the dot row cut is performed). In addition, the dot x ₁₀ at the end of the same column as x _1, the beginning of the dot x ₁₁ of the next row are connected.

Further, as shown in FIG. 3B, the data sequence of the image data at the time (t + 1) used for calculating the correlation coefficient is the n columns on the right side from the state of FIG. 3A (FIG. 3B). 1 row data {y _i } (i =) where the dots of the image data at time (t + 1) after the dot row cut of 2 rows in (1) is sequentially connected from the _first dot y _{1 in the} vertical direction. 1, 2,..., K) (where k is the total number of dots in the image data after the dot row cut is performed). In addition, the dot y ₁₀ at the end of the same column as the y _1, the beginning of the dot y ₁₁ of the next row are connected.

Then, by using such data strings {x _i } and {y _i }, the correlation coefficient C is calculated as the following equation (1).

  In this way, after obtaining the correlation coefficient C for each number of cuts in the dot row, as shown in the graph of FIG. 4, the correlation coefficient C is in the dot traveling direction corresponding to the number of cuts closest to 1. Is the video speed. Note that the video speed may be obtained by converting the displacement amount of the dot corresponding to the number of cuts into a speed per hour [km / h] or a speed per second [m / s], or may be handled as a dot unit. Also good. In FIG. 3B, the image data at the time (t) and the image data at the time (t + 1) coincide with each other by the dot row cut for two rows, so that the converted value to 2 dots or its speed per hour. Is the video speed.

Now, returning to FIG. 2, in the GPS unreceivable period (for example, time t ₂ in FIG. ₂ ) when the host vehicle is traveling in the tunnel, the vehicle speed calculation unit 27 for the autonomous navigation uses the video speed calculation unit 24. The vehicle speed a ′ (= b ′ × K) [km / h for autonomous navigation is obtained by multiplying the video speed b ′ [km / h] calculated during the GPS incapable period by the speed ratio K read from the memory 20. ] Are calculated sequentially.

  Then, the autonomous navigation unit 28 sequentially calculates the autonomous navigation position by using the autonomous navigation vehicle speed a ′ sequentially calculated by the autonomous navigation vehicle speed calculation unit 27.

By such an operation, even when satellite navigation cannot be performed in the tunnel, autonomous navigation can be performed by calculating a vehicle speed for autonomous navigation that can be substituted for the vehicle speed pulse without requiring a vehicle speed pulse. .
(Second operation example)
As a second operation example, as shown in FIG. 5, the vehicle has an in-vehicle camera 3 that takes an image of the upper side of the own vehicle, the own vehicle enters the tunnel, and the upper wall surface of the tunnel is traveling in the tunnel. The operation of the in-vehicle navigation device 1 when the height of the vehicle changes will be described.

As in the first operation example, in the initial state (time t ₀ in FIG. 5), it is assumed that the host vehicle is traveling in front of the entrance of the tunnel. In the initial state, it is assumed that the satellite navigation position calculation by the satellite navigation unit 22 and the video speed calculation by the video speed calculation unit 24 are continuously performed as the host vehicle travels.

When the vehicle enters the tunnel from the initial state, the GPS receiver 5 cannot receive the GPS signal, and the GPS unreceivable period starts (time t ₁ ).

At this time, as shown in FIG. 5, by the speed ratio calculating section 25, divided by the GPS reception not immediately before the vehicle speed _{a 0} [km / h] GPS unreceivable start video rate _{b 0} a shown in FIG. 5 [km / h] Thus, the speed ratio K (= a ₀ / b ₀ ) is calculated, and the calculated speed ratio K is stored in the memory 20.

In the GPS unreceivable period (for example, time t ₂ ) in which the host vehicle is traveling in the tunnel, the autonomous navigation vehicle speed calculating unit 27 sequentially calculates the GPS unreceivable period by the video speed calculating unit 24. By multiplying the video speed b ₁ [km / h] by the speed ratio K read from the memory 20, the vehicle speed for autonomous navigation a ₁ (= b ₁ × K) [km / h] is sequentially calculated.

Then, the autonomous navigation unit 28 sequentially calculates the autonomous navigation position by using the autonomous navigation vehicle speed a ₁ sequentially calculated by the autonomous navigation vehicle speed calculation unit 27.

  Next, when the host vehicle reaches a position where the height of the upper wall surface of the tunnel changes, the video speed change amount becomes equal to or greater than the threshold change amount, and the period after the threshold change starts.

Accordingly, the speed ratio calculating section 25, as shown in FIG. 5, modified by dividing the threshold immediately before the change speed a ₁ by the threshold change at the video rate b _2, which calculates the corrected speed ratio K ', the calculated the speed ratio K ', is stored in the memory 20 (time _t 3).

In the period after the threshold change (for example, time t ₄ ), the vehicle speed calculation unit 27 for autonomous navigation uses the video speed b ₃ [km / h] during the GPS incapability period sequentially calculated by the video speed calculation unit 24. , 'by multiplying the autonomous navigation vehicle speed a _{2 (=} b ₃ × K at the threshold changes after time' corrected speed ratio K read from the memory 20 sequentially calculates a) [km / h].

Then, the autonomous navigation unit 28 sequentially calculates the autonomous navigation position in the period after the threshold change by using the autonomous navigation vehicle speed a ₂ that is sequentially calculated by the autonomous navigation vehicle speed calculation unit 27.

  By such an operation, even when the height of the upper wall surface of the tunnel changes, appropriate autonomous navigation can always be performed following this change.

  In addition, this invention is not limited to embodiment mentioned above, A various change is possible as needed.

  For example, in the case where the in-vehicle camera 3 is arranged so as to be able to photograph the upper side of the own vehicle, when the own vehicle reaches the vicinity of the tunnel or under the overhead by the map matching process, the in-vehicle camera 3 is activated, You may comprise so that power consumption may be suppressed.

The block diagram which shows embodiment of the vehicle-mounted navigation apparatus which concerns on this invention Explanatory drawing for demonstrating the 1st operation example in embodiment of the vehicle-mounted navigation apparatus which concerns on this invention. The figure which shows the image data for demonstrating an example of the calculation method of video speed in embodiment of the vehicle-mounted navigation apparatus which concerns on this invention. The graph which shows the correlation coefficient for demonstrating an example of the calculation method of video speed in embodiment of the vehicle-mounted navigation apparatus which concerns on this invention Explanatory drawing for demonstrating the 1st operation example in embodiment of the vehicle-mounted navigation apparatus which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Car navigation device 3 Car camera 5 GPS receiver 20 Memory 22 Satellite navigation part 23 Satellite navigation vehicle speed calculation part 24 Video speed calculation part 25 Speed ratio calculation part 27 Autonomous navigation vehicle speed calculation part 28 Autonomous navigation part

Claims (11)

An in-vehicle navigation device that does not use a vehicle speed pulse to calculate the vehicle position,
An in-vehicle camera that captures a predetermined imaging area around the host vehicle;
GPS receiving means capable of receiving GPS signals transmitted from GPS satellites;
Satellite navigation means for calculating the vehicle position based on the GPS signal received by the GPS receiving means;
First vehicle speed calculation means for calculating a first vehicle speed based on a time change of the host vehicle position calculated by the satellite navigation means;
Video speed calculating means for calculating a video speed, which is a speed at which the captured video flows in a direction opposite to the traveling direction of the host vehicle, based on a time change of the captured video of the in-vehicle camera;
Speed ratio calculation that calculates a speed ratio that is a value obtained by dividing the first vehicle speed immediately before the time by the video speed at the time when the GPS signal cannot be received by the GPS receiving unit. Means,
Speed ratio storage means for storing the speed ratio calculated by the speed ratio calculation means;
In the GPS unreceivable period, which is a period from the time when reception of the GPS signal becomes impossible to the time when reception of the GPS signal recovers, the speed ratio storage means is stored in the video speed during the GPS unreceivable period. Second vehicle speed calculating means for calculating a second vehicle speed by multiplying the speed ratio stored by
An in-vehicle navigation device comprising: autonomous navigation means for calculating the position of the vehicle in the GPS unreceivable period by using the second vehicle speed calculated by the second vehicle speed calculation means. The speed ratio calculating means determines that the change amount is equal to or greater than the threshold change amount when the change amount of the video speed is greater than or equal to a threshold change amount during the GPS unreceivable period after the start of the GPS unreceivable period. A second speed ratio that is a value obtained by dividing the second vehicle speed immediately before the time point by the video speed at the time point is calculated;
The speed ratio storage means is configured to store the second speed ratio when the second speed ratio is calculated by the speed ratio calculation means,
When the second speed ratio is stored by the speed ratio storage unit, the second vehicle speed calculation unit starts from the time point when the change amount in the GPS unreceivable period is equal to or greater than a threshold change amount. In a part of the period from when the reception of the GPS signal is recovered or until the amount of change becomes equal to or more than the threshold change amount, the video speed in the part of the period is stored by the speed ratio storage unit. The second vehicle speed is calculated using the second speed ratio by multiplying the second speed ratio,
When the second vehicle speed is calculated using the second speed ratio by the second vehicle speed calculation means, the autonomous navigation means uses the second vehicle speed to calculate the first vehicle speed. The vehicle-mounted navigation device according to claim 1, wherein the vehicle-mounted navigation device is configured to calculate a position of the vehicle in a period of the unit. The speed ratio calculation means is configured such that the change amount of the video speed is greater than or equal to a threshold change amount for the Nth time (where N is an arbitrary natural number equal to or greater than 1) during the GPS incapability period after the start of the GPS incapability period. The second vehicle speed immediately before the time when the amount of change becomes equal to or greater than the threshold amount of change for the Nth time is divided by the video speed at the time, thereby the second time of the second time. Configured to calculate the speed ratio,
The speed ratio storage means is configured to store the second speed ratio calculated for the Nth time when the Nth second speed ratio is calculated by the speed ratio calculation means. And
When the second speed ratio calculated by the Nth time is stored by the speed ratio storage means, the second vehicle speed calculating means determines that the amount of change in the GPS unreceivable period is the Nth time. In a part of the Nth time period from when the GPS signal reception is recovered after the threshold change amount is exceeded or until the time when the change amount becomes the threshold change amount again or more, a part of the Nth time By multiplying the video speed in the period by the second speed ratio calculated for the Nth time stored in the speed ratio storage means, the second speed ratio calculated for the Nth time is used. 2 to calculate the vehicle speed,
The autonomous navigation means calculates the second vehicle speed when the second vehicle speed is calculated using the second speed ratio calculated for the Nth time by the second vehicle speed calculation means. The in-vehicle navigation device according to claim 2, wherein the vehicle-mounted navigation device is configured to calculate a position of the vehicle in the N-th partial period. With an acceleration sensor,
The speed ratio calculation means is configured to calculate the second speed ratio when the calculation result of the acceleration sensor is equal to or less than the threshold acceleration at the time when the change amount is equal to or greater than the threshold change amount. The in-vehicle navigation device according to claim 2 or claim 3, wherein The speed ratio calculating means is configured such that the change amount becomes equal to or greater than the threshold change amount again from a first time point when the change amount becomes equal to or greater than the threshold change amount during the GPS unreceivable period after the start of the GPS unreceivable period. When the time until the second time point is detected and the detected time is less than the threshold time, the amount of change in the video speed at the second time point is ignored, and the time at the second time point is ignored. The in-vehicle navigation device according to any one of claims 2 to 4, wherein the second speed ratio is not calculated. The video speed calculation means divides a video image taken by the in-vehicle camera into a plurality of video areas, calculates a video speed for each video area based on a temporal change of the video for each divided video area, At any point in time during the GPS non-receivable period after the start of the GPS non-receivable period, the number of the video areas is such that the amount of change in the video speed for each video area is equal to or greater than the threshold change amount. If not, the average value of the video speed for each video area in the other video areas excluding the video area where the change amount of the video speed for each video area is equal to or greater than the threshold change amount, The in-vehicle navigation system according to any one of claims 2 to 5, wherein the in-vehicle navigation system is configured to have the video speed used for calculating the second vehicle speed at an arbitrary time point. Gating device. The in-vehicle navigation device according to any one of claims 1 to 6, wherein the in-vehicle camera is disposed so as to be capable of photographing the upper side of the host vehicle. The in-vehicle navigation device according to claim 7, wherein the GPS incapable period is a period in which the host vehicle is traveling in a tunnel or under an overpass. The in-vehicle camera is arranged so as to be able to photograph the left side and the right side of the host vehicle,
The video speed calculating means includes a left-side video speed calculated based on a time change of the left-side shot video, and a right-side video speed calculated based on a time change of the right-side shot video. The in-vehicle navigation system according to any one of claims 1 to 6, wherein an average value of the vehicle speed is used as a calculation result of the video speed used for the calculation of the second vehicle speed. apparatus. The in-vehicle navigation device according to claim 9, wherein the GPS incapable period is a period in which the host vehicle is traveling in a valley of a high-rise building. The vehicle-mounted navigation device according to any one of claims 1 to 10, wherein the vehicle-mounted camera is directly mounted on a vehicle-mounted navigation device main body.

Images