Patent Description:
In recent years, in order to curb air pollution, low emission zones (LEZ) which require a vehicle to stop its internal combustion engine when driving through them have been established in locations such as urban areas with large amounts of traffic. When a hybrid vehicle provided with an internal combustion engine and an electric motor is driving through such a low emission zone, it is necessary to stop the internal combustion engine and use only the electric motor to output power for driving use.

In this regard, PTL <NUM> discloses using a GNSS receiver to estimate the position of a hybrid vehicle and making the internal combustion engine stop if the position of the hybrid vehicle is within a low emission zone ("reinforced air pollution preventing region" in PTL <NUM>).

<CIT> makes reference to a method comprising a step of determining a regulatory constraint for a geographical area taken by the vehicle, this stage comprising an automated optical reading of a road sign of the geographical area taken, reading automated optics recording a set of information of the regulatory constraint concerning a mode of propulsion of the vehicle for the geographical area taken, and a warning step of the regulatory constraint intended for the driver.

However, sometimes the precision of estimation of the position by a GNSS receiver drops depending on the driving environment etc. In such a case, erroneous position recognition is liable to cause the internal combustion engine to be driven despite the position of the hybrid vehicle being in a low emission zone.

Therefore, in consideration of the above problem, an object of the present invention is to suppress erroneous recognition of the position of a hybrid vehicle in the vicinity of a low emission zone when the precision of detection by a GNSS receiver drops.

In order to solve the problem posed, a system according to claim <NUM> and a method according to claim <NUM> are provided.

According to the present invention, it is possible to suppress erroneous recognition of the position of a hybrid vehicle in the vicinity of a low emission zone when the precision of detection by a GNSS receiver drops.

Below, referring to the drawings, embodiments of the present invention will be explained in detail. Note that, in the following explanation, similar component elements will be assigned the same reference notations.

First, referring to <FIG>, a first embodiment of the present invention will be explained.

<FIG> is a view showing one example of the configuration of a hybrid vehicle <NUM> in which a position estimation system according to the first embodiment of the present invention is provided. The hybrid vehicle <NUM> is provided with an imaging device 11a, an internal combustion engine <NUM>, a first motor-generator <NUM>, a power splitting mechanism <NUM>, a second motor-generator <NUM>, a power control unit (PCU) <NUM>, a battery <NUM>, and a speed reducer <NUM>.

The imaging device 11a captures the outside the hybrid vehicle <NUM> to generate an image. For example, the imaging device 11a is arranged at the front of the hybrid vehicle <NUM> (for example, the back of a rear-view mirror, a front bumper, etc.) so as to capture the area in front of the hybrid vehicle <NUM>.

The internal combustion engine <NUM> outputs power by burning a mixture of fuel and air inside its cylinders and is, for example, a gasoline engine or a diesel engine. The output shaft (crankshaft) of the internal combustion engine <NUM> is mechanically connected to the power splitting mechanism <NUM>, and the output of the internal combustion engine <NUM> is input to the power splitting mechanism <NUM>.

The power splitting mechanism <NUM> is configured as a known planetary gear mechanism including a sun gear, a ring gear, a pinion gear, and a planetary carrier. The power splitting mechanism <NUM> distributes the output of the internal combustion engine <NUM> between the first motor-generator <NUM> and the speed reducer <NUM>. The output of the internal combustion engine <NUM> distributed to the speed reducer <NUM> is transmitted as power for driving use to wheels <NUM> through an axle <NUM>. Therefore, the internal combustion engine <NUM> can output power for driving use.

The first motor-generator <NUM> functions as a generator and a motor. When the first motor-generator <NUM> functions as a generator, the output of the internal combustion engine <NUM> is supplied through the power splitting mechanism <NUM> to the first motor-generator <NUM>. The first motor-generator <NUM> uses the output of the internal combustion engine <NUM> to generate electrical power. The electrical power generated by the first motor-generator <NUM> is supplied through the PCU <NUM> to at least one of the second motor-generator <NUM> and the battery <NUM>.

On the other hand, when the first motor-generator <NUM> functions as a motor, the electrical power stored in the battery <NUM> is supplied through the PCU <NUM> to the first motor-generator <NUM>. The output of the first motor-generator <NUM> is supplied through the power splitting mechanism <NUM> to the output shaft of the internal combustion engine <NUM>, and the internal combustion engine <NUM> is cranked.

The second motor-generator <NUM> functions as a motor and a generator. When the second motor-generator <NUM> functions as a motor, at least one of the electrical power generated by the first motor-generator <NUM> and the electrical power stored in the battery <NUM> is supplied to the second motor-generator <NUM>. The output of the second motor-generator <NUM> is supplied to the speed reducer <NUM>, and the output of the second motor-generator <NUM> supplied to the speed reducer <NUM> is transmitted as power for driving use to the wheels <NUM> through the axle <NUM>. Therefore, the second motor-generator <NUM> can output power for driving use. The second motor-generator <NUM> is one example of an electric motor.

On the other hand, when the hybrid vehicle <NUM> is decelerating, the second motor-generator <NUM> is driven by the rotation of the wheels <NUM>, and the second motor-generator <NUM> functions as a generator. At this time, so-called regeneration is performed, and the regenerated electrical power generated by the second motor-generator <NUM> is supplied through the PCU <NUM> to the battery <NUM>.

The PCU <NUM> has an inverter, a step-up converter, and a DC-DC converter and is electrically connected to the first motor-generator <NUM>, the second motor-generator <NUM>, and the battery <NUM>. The PCU <NUM> converts DC electrical power supplied from the battery <NUM> to AC electrical power and converts AC electrical power generated by the first motor-generator <NUM> or the second motor-generator <NUM> to DC electrical power.

The battery <NUM> is supplied with the electrical power generated by the first motor-generator <NUM> using the output of the internal combustion engine <NUM> and the regenerated electrical power generated by the second motor-generator <NUM> using regenerated energy. Therefore, the battery <NUM> can be charged by the output of the internal combustion engine <NUM> and the regenerated energy. The battery <NUM> is a lithium-ion battery, a nickel-hydrogen battery, or other secondary battery.

Further, the hybrid vehicle <NUM> is provided with a charging port <NUM> and a charger <NUM>. The battery <NUM> can also be charged by an external power source <NUM>. That is, the hybrid vehicle <NUM> shown in <FIG> is a so-called plug-in hybrid vehicle.

The charging port <NUM> is configured to receive electrical power from the external power source <NUM> through a charging connector <NUM> of a charging cable <NUM>. When the battery <NUM> is charged by the external power source <NUM>, the charging connector <NUM> is connected to the charging port <NUM>. The charger <NUM> converts the electrical power supplied from the external power source <NUM> to electrical power which can be supplied to the battery <NUM>.

Further, an SOC (state of charge) sensor 15a for detecting a state quantity of the battery <NUM> (voltage, current, etc.) for calculation of the SOC of the battery <NUM> is provided at the battery <NUM>.

Note that the first motor-generator <NUM> may be a generator which does not function as a motor. Further, the second motor-generator <NUM> may be a motor which does not function as a generator. Further, the charging port <NUM> may be connected to the PCU <NUM>, and the PCU <NUM> may function as the charger <NUM>.

<FIG> is a view schematically showing the configuration of the position estimation system <NUM> according to the first embodiment of the present invention. The position estimation system <NUM> is mounted in the hybrid vehicle <NUM> and estimates the position (current position) of the hybrid vehicle <NUM>.

As shown in <FIG>, the position estimation system <NUM> is provided with an imaging device 11a, a GNSS receiver <NUM>, a map database <NUM>, a navigation device <NUM>, sensors <NUM>, and an electronic control unit (ECU) <NUM>. The imaging device 11a, the GNSS receiver <NUM>, the map database <NUM>, the navigation device <NUM>, and sensors <NUM> are provided in the hybrid vehicle <NUM> and are connected to the ECU <NUM> to be able to communicate through an internal vehicle network based on the CAN (Controller Area Network) or other standard.

The imaging device 11a detects objects in the surroundings of the hybrid vehicle <NUM> by capturing the outside the hybrid vehicle <NUM> and generating an image. The imaging device 11a is one example of an object detection device for detecting objects in the surroundings of the hybrid vehicle <NUM>. The output of the imaging device 11a is transmitted to the ECU <NUM>.

The GNSS receiver <NUM> captures a plurality of positioning satellites and receives radio waves transmitted from the positioning satellites. The GNSS receiver <NUM> calculates the distance to the positioning satellites based on the difference between the time of transmission and time of reception of the radio waves and detects the current position of the hybrid vehicle <NUM> (for example, the longitude and latitude of the hybrid vehicle <NUM>) based on the distances to the positioning satellites and the positions of the positioning satellites (orbit information). The output of the GNSS receiver <NUM> is transmitted to the ECU <NUM>, and the ECU <NUM> acquires the current position of the hybrid vehicle <NUM> from the GNSS receiver <NUM>. Note that GNSS (Global Navigation Satellite System) is an umbrella term for the U. ' GPS, Russia's GLONASS, Europe's Galileo, Japan's QZSS, China's BeiDou, India's IRNSS, and other satellite positioning systems. That is, the GNSS receiver <NUM> includes a GPS receiver.

The map database <NUM> stores map information. The ECU <NUM> acquires the map information from the map database <NUM>.

The navigation device <NUM> sets a driving route of the hybrid vehicle <NUM> to a destination based on the current position of the hybrid vehicle <NUM> detected by the GNSS receiver <NUM>, the map information from the map database <NUM>, inputs from the driver, etc. The driving route set by the navigation device <NUM> is transmitted to the ECU <NUM>. Note that the GNSS receiver <NUM> and map database <NUM> may be incorporated in the navigation device <NUM>.

The sensors <NUM> detect state quantities relating to the hybrid vehicle <NUM> and include a vehicle speed sensor, a gyro sensor, a SOC sensor 15a, etc. The outputs of the sensors <NUM> are transmitted to the ECU <NUM>, and the ECU <NUM> acquires the state quantities detected by the sensors <NUM>.

The ECU <NUM> is provided at the hybrid vehicle <NUM> and executes various types of control of the hybrid vehicle <NUM>. Note that, in the present embodiment, one ECU <NUM> is provided, but a plurality of ECUs may be provided for each function.

As shown in <FIG>, the ECU <NUM> includes a communication interface <NUM>, a memory <NUM>, and a processor <NUM>. The communication interface <NUM>, a memory <NUM>, and a processor <NUM> are connected to each other through signal wires.

The communication interface <NUM> has an interface circuit for connecting the ECU <NUM> to an internal vehicle network based on the CAN or other standard. The ECU <NUM> communicates with other vehicle-mounted equipment such as mentioned above through the communication interface <NUM>.

The memory <NUM> has, for example, a volatile semiconductor memory (for example, a RAM) and a non-volatile semiconductor memory (for example, a ROM). The memory <NUM> stores programs to be executed by the processor <NUM>, various data to be used when the processor <NUM> is executing various processes, etc..

The processor <NUM> has one or more CPUs (central processing units) and peripheral circuits therefor and executes various processing. Note that the processor <NUM> may further have a processing circuit such as a logic unit or an arithmetic unit.

<FIG> is a functional block diagram of the ECU <NUM> of the first embodiment. In the present embodiment, the ECU <NUM> has an identifying part <NUM> and a position estimating part <NUM>. The identifying part <NUM> and the position estimating part <NUM> are functional modules realized by the processor <NUM> of the ECU <NUM> running programs stored in the memory <NUM> of the ECU <NUM>.

The identifying part <NUM> identifies objects detected by the imaging device 11a. The position estimating part <NUM> estimates the position of the hybrid vehicle <NUM> based on the output of the GNSS receiver <NUM>.

In this regard, in order to curb air pollution, low emission zones (LEZ) which require a vehicle to stop its internal combustion engine when driving through them have been established in locations such as urban areas with large amounts of traffic. In such low emission zones, operating internal combustion engines is banned or restricted. In principle, only vehicles that can travel without emitting exhaust gas (for example, hybrid vehicles, electric cars, fuel cell vehicles, etc.) are allowed to pass. If an internal combustion engine is operated in a low emission zone, a fine or the like is imposed on the driver of the vehicle.

Therefore, when a hybrid vehicle <NUM> is driving through such a low emission zone, it is necessary to make the internal combustion engine <NUM> stop. For this reason, as much as possible, the hybrid vehicle <NUM> makes the internal combustion engine <NUM> stop and uses only the second motor-generator <NUM> to output power for driving use when in a low emission zone.

However, depending on the driving environment etc., sometimes the precision of estimation of the position by the GNSS receiver <NUM> drops. In such cases, erroneous position recognition is liable to cause the internal combustion engine <NUM> to be operated despite the position of the hybrid vehicle <NUM> being in a low emission zone.

For this reason, it is desirable to be able to grasp the position of the hybrid vehicle <NUM> by means other than the GNSS receiver <NUM> in the vicinity of a low emission zone. In this regard, the boundary of a low-emission zone (also called a "geofence") is provided with a sign indicating the boundary of the low emission zone to make drivers aware of the range of the low emission zone. The sign can be a sign board, a sign post, an electronic sign, etc., indicating the boundary of the low emission zone by text, symbols, graphics, or a combination thereof. One example of such a sign is shown in <FIG>.

Therefore, in the vicinity of a low emission zone, it is possible to judge whether the hybrid vehicle <NUM> is located within the low emission zone using a sign indicating the boundary of the low emission zone as an indicator. However, the result of detection of a sign by the imaging device 11a is not necessarily always correct.

For this reason, in the present embodiment, if a predetermined condition is satisfied and an object identified by the identifying part <NUM> is a sign indicating a boundary of a low emission zone, the position estimating part <NUM> judges whether the hybrid vehicle <NUM> is located within a low emission zone, regardless of the output of the GNSS receiver <NUM>, based on the result of identification by the identifying part <NUM>. By doing so, it is possible to suppress erroneous recognition of the position of the hybrid vehicle <NUM> in the vicinity of a low emission zone when the precision of detection by the GNSS receiver <NUM> drops.

A sign indicating a boundary of a low emission zone shows entrance to or exit from the low emission zone. For this reason, the position estimating part <NUM> judges that the hybrid vehicle <NUM> is located within a low emission zone, regardless of the output of the GNSS receiver <NUM>, if a predetermined condition is satisfied and the object identified by the identifying part <NUM> is a sign indicating entrance to a low emission zone. On the other hand, the position estimating part <NUM> judges that the hybrid vehicle <NUM> is not located within a low emission zone, regardless of the output of the GNSS receiver <NUM>, if a predetermined condition is satisfied and the object identified by the identifying part <NUM> is a sign indicating exit from a low emission zone.

Below, the above-explained control will be explained in detail using the flow chart of <FIG> is a flow chart showing a control routine for processing for estimating a position in the first embodiment of the present invention. The present control routine is repeatedly executed by the ECU <NUM> at predetermined execution intervals.

First, at step S101, the identifying part <NUM> identifies an object detected by the imaging device 11a. For example, the identifying part <NUM> uses a trained neural network model to identify the object detected by the imaging device 11a. In such a case, the neural network model employs a structure such as that of a CNN (Convolutional Neural Network), Faster R-CNN, SSD (Single Shot Multibox Detector), YOLO (You Only Look Once), etc. When image data for an image generated by the imaging device 11a is input into the trained neural network model, the trained neural network model outputs a result of identification and confidence of the result of identification.

Next, at step S102, the position estimating part <NUM> judges whether a predetermined condition is satisfied. For example, the predetermined condition includes that the confidence output by the trained neural network model is equal to or greater than a predetermined value. That is, the position estimating part <NUM> judges that the predetermined condition is satisfied if the confidence output by the trained neural network model is equal to or greater than the predetermined value. The predetermined value is set to, for example, <NUM> to <NUM> if the confidence is expressed as a numerical value of <NUM> to <NUM>.

Note that in addition to or in place of the above-explained condition, the predetermined condition may include that the hybrid vehicle <NUM> is located in the vicinity of a low emission zone. The position estimating part <NUM> judges that the hybrid vehicle <NUM> is located in the vicinity of a low emission zone if the shortest distance between the position of the hybrid vehicle <NUM> estimated based on the output of the GNSS receiver <NUM> and the low emission zone (for example, the center position of the low emission zone) within a predetermined time up to the present is equal to or less than a predetermined distance.

If it is judged at step S102 that the predetermined condition is satisfied, the present control routine proceeds to step S103. At step S103, the position estimating part <NUM> judges whether the object identified by the identifying part <NUM>, that is, the result of identification from the identifying part <NUM>, is a sign indicating a boundary of a low emission zone. If it is judged that the object identified by the identifying part <NUM> is a sign indicating a boundary of a low emission zone, the present control routine proceeds to step S104.

At step S104, the position estimating part <NUM> judges whether the sign indicating a boundary of a low emission zone is a sign indicating exit from a low emission zone. For example, the position estimating part <NUM> judges whether the sign indicating a boundary of a low emission zone is a sign indicating exit from a low emission zone based on history data of the position of the hybrid vehicle <NUM>, the driving route set by the navigation device <NUM>, etc. Specifically, the position estimating part <NUM> judges that the sign indicating a boundary of a low emission zone is a sign indicating exit from a low emission zone if the current position of the hybrid vehicle <NUM> estimated based on the above information is within the low emission zone.

Further, sometimes a sign indicating a boundary of a low emission zone may itself be provided with an indicator indicating entrance to or exit from a low emission zone. For this reason, images of signs indicating entrance to low emission zones and images of signs indicating exit from low emission zones may be employed as teacher data for training the neural network model, and the trained neural network model may output a sign indicating entrance to a low emission zone and a sign indicating exit from a low emission zone as separate results of identification. In such a case, the position estimating part <NUM> judges whether the sign indicating a boundary of a low emission zone is a sign indicating exit from a low emission zone based on the result of identification output from the trained neural network model.

If it is judged at step S104 that the sign indicating a boundary of a low emission zone is a sign indicating entrance to a low emission zone, the present control routine proceeds to step S105. At step S105, the position estimating part <NUM> judges that the hybrid vehicle <NUM> is located within a low emission zone. In such a case, the internal combustion engine <NUM> of the hybrid vehicle <NUM> is stopped and only the second motor-generator <NUM> is used to output power for driving use. After step S105, the present control routine ends.

On the other hand, if it is judged at step S104 that the sign indicating a low emission zone boundary is a sign indicating exit from a low emission zone, the present control routine proceeds to step S106. At step S106, the position estimating part <NUM> judges that the hybrid vehicle <NUM> is not located within the low emission zone. In other words, the position estimating part <NUM> judges that the hybrid vehicle 1is located outside the low emission zone. In such a case, for example, operation of the internal combustion engine <NUM> of the hybrid vehicle <NUM> is permitted after a predetermined time and the internal combustion engine <NUM> is operated in accordance with the vehicle state of the hybrid vehicle <NUM> (demanded output, SOC of the battery <NUM>, etc.). After step S106, the present control routine ends.

Further, if it is judged at step S102 that the predetermined condition is not satisfied or if it is judged at step S103 that the object identified by the identifying part <NUM> is not a sign indicating a boundary of a low emission zone, the present control routine proceeds to step S107. At step S107, the position estimating part <NUM> estimates the position (current position) of the hybrid vehicle <NUM> based on the output of the GNSS receiver <NUM>.

For example, the position estimating part <NUM> uses the map information of the map database <NUM>, the output of the GNSS receiver <NUM>, and a known autonomous navigation technique (dead reckoning) to estimate the position of the hybrid vehicle <NUM>. Specifically, the position estimating part <NUM> specifies a reference point (base point) on a map based on the map information of the map database <NUM> and the output of the GNSS receiver <NUM> and calculates the distance of travel and the direction of travel of the hybrid vehicle <NUM> with respect to the reference point based on the outputs of sensors <NUM> such as the vehicle speed sensor and the gyro sensor to estimate the position of the hybrid vehicle <NUM>. Position information of low emission zones is stored in the map information of the map database <NUM>. The position estimating part <NUM> compares the estimated position of the hybrid vehicle <NUM> with low emission zone ranges to judge whether the hybrid vehicle <NUM> is located within a low emission zone. After step S107, the present control routine ends.

Note that a sign indicating a boundary of a low emission zone is often placed only at the entrance to a low emission zone (for example, the side of a road heading toward a low emission zone). For this reason, steps S104 and S106 may be omitted. That is, the position estimating part <NUM> may judge that the hybrid vehicle <NUM> is located within a low emission zone, regardless of the output of the GNSS receiver <NUM>, if the predetermined condition is satisfied and the object identified by the identifying part <NUM> is a sign indicating a boundary of a low emission zone.

Further, the identifying part <NUM> may identify an object detected by the imaging device 11a using pattern matching, SURF (Speeded-Up Robust Features), or another image recognition technique not based on a neural network. In such a case, the predetermined condition in step S102 includes, for example, the current driving environment of the hybrid vehicle <NUM> not being a predetermined driving environment in which the precision of detection by the imaging device 11a worsens. The predetermined travel environment includes, for example, thick fog, heavy rain, nighttime, etc., and is detected by sensors <NUM> such as a rain sensor, a light sensor, etc..

The configuration and control of a position estimation system according to a second embodiment are basically similar to the configuration and control of the position estimation system according to the first embodiment with the exception of the points explained below. For this reason, below, the parts of the second embodiment of the present invention different from the first embodiment will be focused on in the explanation.

<FIG> is a view schematically showing the configuration of a hybrid vehicle <NUM>' in which the position estimation system according to the second embodiment of the present invention is provided. In the second embodiment, the hybrid vehicle <NUM>' is provided with a road-to-vehicle communication device 11b. The road-to-vehicle communication device 11b is a device which enables communication between the hybrid vehicle <NUM>' and a road-side device <NUM>.

<FIG> is a view schematically showing the configuration of the position estimation system <NUM>' according to the second embodiment of the present invention. The position estimation system <NUM>' comprises a road-to-vehicle communication device 11b, a GNSS receiver <NUM>, a map database <NUM>, a navigation device <NUM>, sensors <NUM>, and an ECU <NUM>. The road-to-vehicle communication device 11b, the GNSS receiver <NUM>, the map database <NUM>, the navigation device <NUM>, and the sensors <NUM> are provided in the hybrid vehicle <NUM>' and are connected to the ECU <NUM> to be able to communicate through an internal vehicle network based on the CAN or other standard.

Therefore, in the second embodiment, the position estimation system <NUM>' is provided with the road-to-vehicle communication device 11b in place of the imaging device 11a. The road-to-vehicle communication device 11b receives radio waves from road-side devices <NUM> to detect the road-side devices in the surroundings of the hybrid vehicle <NUM>'. The road-to-vehicle communication device 11b is one example of an object detection device for detecting objects in the surroundings of the hybrid vehicle <NUM>'. The information contained in radio waves received by the road-to-vehicle communication device 11b is transmitted to the ECU <NUM>. Note that the road-to-vehicle communication device 11b may be assembled into the navigation device <NUM>.

Meanwhile, in addition to or in place of signs indicating boundaries of low emission zone, road-side devices such as ETC (Electronic Toll Collection System) <NUM> road-side devices are sometimes provided at the boundaries of low emission zones to make drivers be aware of the range of low emission zones. In such a case, it is possible to judge whether the hybrid vehicle <NUM>' is located within a low emission zone by detecting such road-side devices.

For this reason, in the second embodiment, if a predetermined condition is satisfied and the object identified by the identifying part <NUM> is a road-side device indicating a boundary of a low emission zone, the position estimating part <NUM> judges whether the hybrid vehicle <NUM> is located within a low emission zone, regardless of the output of the GNSS receiver <NUM>, based on the result of identification by the identifying part <NUM>. By doing so, it is possible to suppress erroneous recognition of the position of the hybrid vehicle <NUM>' in the vicinity of a low emission zone when the precision of detection by the GNSS receiver <NUM> drops.

A road-side device indicating a boundary of a low emission zone indicates an entrance to or exit from a low emission zone. For this reason, the position estimating part <NUM> judges that the hybrid vehicle <NUM>' is located within a low emission zone, regardless of the output of the GNSS receiver <NUM>, if the predetermined condition is satisfied and the object identified by the identifying part <NUM> is a road-side device indicating an entrance to a low emission zone. On the other hand, the position estimating part <NUM> judges that the hybrid vehicle <NUM>' is not located within a low emission zone, regardless of the output of the GNSS receiver <NUM>, if the predetermined condition is satisfied and the object identified by the identifying part <NUM> is a road-side device indicating exit from a low emission zone.

<FIG> is a flow chart showing a control routine for processing for estimating a position in the second embodiment of the present invention. The present control routine is repeatedly executed by the ECU <NUM> at predetermined execution intervals.

First, at step S201, the identifying part <NUM> judges whether a road-side device is detected by the road-to-vehicle communication device 11b. Specifically, the identifying part <NUM> judges whether the road-to-vehicle communication device 11b has received radio waves from a road-side device. When it is judged that a road-side device is detected by the road-to-vehicle communication device 11b, the present control routine proceeds to step S202.

At step S202, the identifying part <NUM> identifies the road-side device detected by the road-to-vehicle communication device 11b. Specifically, the identifying part <NUM> identifies the road-side device based on the information contained in the radio waves transmitted from the road-side device to the road-to-vehicle communication device 11b.

Next, at step S203, the position estimating part <NUM> judges whether a predetermined condition is satisfied. For example, the predetermined condition includes the hybrid vehicle <NUM>' being located in the vicinity of a low emission zone. The position estimating part <NUM> judges that the hybrid vehicle <NUM>' is located in the vicinity of a low emission zone if the shortest distance between the position of the hybrid vehicle <NUM>' estimated based on the output of the GNSS receiver <NUM> and the low emission zone (for example, the center position of the low emission zone) within a predetermined time up to the present is equal to or less than a predetermined distance.

If it is judged at step S203 that the predetermined condition is satisfied, the present control routine proceeds to step S204. At step S204, the position estimating part <NUM> judges whether the object identified by the identifying part <NUM>, that is, the road-side device identified by the identifying part <NUM>, is a road-side device indicating a boundary of a low emission zone. If it is judged that the object identified by the identifying part <NUM> is a road-side device indicating a boundary of a low emission zone, the present control routine proceeds to step S205.

At step S205, the position estimating part <NUM> judges whether the road-side device indicating a boundary of a low emission zone is a road-side device indicating exit from a low emission zone based on the information contained in the radio waves transmitted from the road-side device to the road-to-vehicle communication device 11b. Note that if information for performing the above judgment is not contained in the radio waves, the position estimating part26, for example, judges whether the road-side device indicating a boundary of a low emission zone is a road-side device indicating exit from a low emission zone based on the history data of the position of the hybrid vehicle <NUM>', the driving route set by the navigation device <NUM>, etc. Specifically, the position estimating part <NUM> judges that the road-side device indicating a boundary of a low emission zone is a road-side device indicating exit from a low emission zone if the current position of the hybrid vehicle <NUM>' estimated based on the above information is within a low emission zone.

If it is judged at step S205 that the road-side device indicating a boundary of a low emission zone is a road-side device indicating an entrance to a low emission zone, the present control routine proceeds to step S206. At step S206, the position estimating part <NUM> judges that the hybrid vehicle <NUM>' is located within a low emission zone. In such a case, the internal combustion engine <NUM> of the hybrid vehicle <NUM>' is stopped and only the second motor-generator <NUM> is used to output power for driving use. After step S206, the present control routine ends.

On the other hand, if it is judged at step S205 that the road-side device indicating a boundary of a low emission zone is a road-side device indicating exit from a low emission zone, the present control routine proceeds to step S207. At step S207, the position estimating part <NUM> judges that the hybrid vehicle <NUM>' is not located within a low emission zone. In other words, the position estimating part <NUM> judges that the hybrid vehicle <NUM>' is outside the low emission zone. In such a case, for example, operation of the internal combustion engine <NUM> of the hybrid vehicle <NUM>' is permitted after a predetermined time and the internal combustion engine <NUM> is operated in accordance with the vehicle state of the hybrid vehicle <NUM>' (demanded output, SOC of the battery <NUM>, etc.). After step S207, the present control routine ends.

Further, if it is judged at step S201 that a road-side device is not detected by the road-to-vehicle communication device 11b, if it is judged at step S203 that the predetermined condition is not satisfied, or if it is judged at step S204 that the object identified by the identifying part <NUM> is not a road-side device indicating a boundary of a low emission zone, the present control routine proceeds to step S208. At step S208, in the same way as step S107 of <FIG>, the position estimating part26 estimates the position (current position) of the hybrid vehicle <NUM>' based on the output of the GNSS receiver <NUM>. After step S208, the present control routine ends.

Note that usually a road-side device indicating a boundary of a low emission zone is placed only at an entrance to a low emission zone (for example, the side of a road leading to a low emission zone). For this reason, steps S205 and S207 may be omitted. That is, the position estimating part <NUM> may judge that the hybrid vehicle <NUM>'is located within a low emission zone, regardless of the output of the GNSS receiver <NUM>, if the predetermined condition is satisfied and the object identified by the identifying part <NUM> is a road-side device indicating a boundary of a low emission zone.

The configuration and control of a position estimation system according to a third embodiment are basically similar to the configuration and control of the position estimation system according to the first embodiment with the exception of the points explained below. For this reason, below, the parts of the third embodiment of the present invention different from the first embodiment will be focused on in the explanation.

<FIG> is a functional block diagram for the ECU <NUM> in the third embodiment. In the third embodiment, the ECU <NUM> has a reliability calculating part <NUM> in addition to the identifying part <NUM> and the position estimating part <NUM>. The reliability calculating part <NUM> calculates the reliability of the results of the output of the GNSS receiver <NUM>. The identifying part <NUM>, the position estimating part <NUM>, and the reliability calculating part <NUM> are functional modules realized by the processor <NUM> of the ECU <NUM> running programs stored in the memory <NUM> of the ECU <NUM>.

As explained above, if a predetermined condition is satisfied and the object identified by the identifying part <NUM> is a sign indicating a boundary of a low emission zone, the position estimating part <NUM> judges whether the hybrid vehicle <NUM> is located within a low emission zone, regardless of the output of the GNSS receiver <NUM>, based on the result of identification from the identifying part <NUM>. In the third embodiment, the predetermined condition includes the reliability calculated by the reliability calculating part <NUM> being equal to or less than a reference value.

<FIG> is a flow chart showing a control routine for processing for estimating a position in the third embodiment of the present invention. The present control routine is repeatedly executed by the ECU <NUM> at predetermined execution intervals.

First, at step S301, in the same way as step S101 of <FIG>, the identifying part <NUM> identifies the object detected by the imaging device 11a.

Next, at step S302, the reliability calculating part <NUM> calculates the reliability of the output of the GNSS receiver <NUM> (below, simply referred to as the "reliability"). For example, the reliability calculating part <NUM> calculates the reliability based on the reception state of the GNSS receiver <NUM>. In such a case, the reliability calculating part <NUM>, for example, calculates the reliability of the position information based on the number of positioning satellites captured by the GNSS receiver <NUM> and, when the number of positioning satellites captured by the GNSS receiver <NUM> is equal to or less than a predetermined number (for example, <NUM> or <NUM>), calculates the reliability as a value equal to or less than a reference value. Further, the reliability calculating part <NUM> may calculate the reliability based on a DOP (Dilution of Precision) value relating to the GNSS receiver <NUM> and, when the DOP value is equal to or greater than a predetermined value, calculate the reliability as a value equal to or less than the reference value Tref. In such a case, the DOP value can be the value of any one of HDOP (horizontal dilution of precision) and VDOP (vertical dilution of precision) or the average of the HDOP and VDOP values.

Further, in a so-called cold start state where the GNSS receiver <NUM> is restarted after the orbit information of the positioning satellites is erased due to time elapse or the like, capturing the positioning satellites to receive radio waves will take time. For this reason, when the supply of power to the GNSS receiver <NUM> stops for equal to or greater than a predetermined time, the reliability calculating part <NUM> may calculate the reliability as a value equal to or less than the reference value. The predetermined time is set to the time from when the supply of power to the GNSS receiver <NUM> is stopped to when the orbit information of the positioning satellites is erased. That is, when a cold start of the GNSS receiver <NUM> is performed, the reliability calculating part <NUM> may calculate the reliability as a value equal to or less than the reference value.

Further, when the hybrid vehicle <NUM> is transported by a ferry, an auto-transport trailer, etc., the position of the hybrid vehicle <NUM> cannot be estimated using the autonomous navigation technique. For this reason, when the hybrid vehicle <NUM> is transported, the reliability calculating part <NUM> may calculate the reliability as a value equal to or less than the reference value.

Immediately after the hybrid vehicle <NUM> has been transported, the general position of the hybrid vehicle <NUM> can be grasped based on the output of the GNSS receiver <NUM>. For this reason, the hybrid vehicle <NUM> having been transported may be determined based on, for example, the output of the GNSS receiver <NUM>. When the position of the hybrid vehicle <NUM> has greatly changed at the time the GNSS receiver <NUM> is restarted, it is judged that the hybrid vehicle <NUM> has been transported. Further, the hybrid vehicle <NUM> having been transported by a ferry may be determined based on the driving route set by the navigation device <NUM>.

Further, when the advancing direction of the hybrid vehicle <NUM> is changed by a turntable in a location such as a multistory parking lot, the position of the hybrid vehicle <NUM> estimated by the autonomous navigation technique will deviate from the actual position. For this reason, when the advancing direction of the hybrid vehicle <NUM> is changed by a turntable, the reliability calculating part <NUM> may calculate the reliability as a value equal to or less than the reference value. For example, information relating to a parking lot (for example, whether or not a turntable is present) is stored in the map information of the map database <NUM> and, when the hybrid vehicle <NUM> has parked in a parking lot with a turntable, it is judged that the advancing direction of the hybrid vehicle <NUM> has been changed by the turntable.

Further, sometimes a portable terminal (for example, a smartphone, a tablet terminal, a laptop, etc.) brought into the hybrid vehicle <NUM> by the driver or the like is electrically connected to the hybrid vehicle <NUM> (specifically, the ECU <NUM>) by a cable or wireless connection. In such cases, when the distance between the position of the hybrid vehicle <NUM> estimated by the position estimating part <NUM> and the position of the hybrid vehicle <NUM> detected by the portable terminal is equal to or greater than a predetermined distance, the reliability calculating part <NUM> may calculate the reliability of the position information as a value equal to or less than the reference value.

Next, at step S303, the position estimating part <NUM> judges whether a predetermined condition is satisfied. The predetermined condition includes, in addition to or in place of the above-explained condition relating to the first embodiment, the reliability calculated by the reliability calculating part <NUM> being equal to or less than the reference value. The reference value is predetermined.

After step S303, step S304 to step S308 are executed in the same way as step S103 to step S107 of <FIG>. Note that the present control routine can be modified in the same way as the control routine of <FIG>.

The configuration and control of a position estimation system according to a fourth embodiment are basically similar to the configuration and control of the position estimation system according to the first embodiment with the exception of the points explained below. For this reason, below, the parts of the fourth embodiment of the present invention different from the first embodiment will be focused on in the explanation.

<FIG> is a schematic view of the configuration of a client-server system <NUM> including a hybrid vehicle <NUM>" in which the position estimation system according to the fourth embodiment of the present invention is provided. The client-server system <NUM> comprises the hybrid vehicle <NUM>" and a server <NUM>. The server <NUM> is capable of communicating with a plurality of vehicles including the hybrid vehicle <NUM>".

As shown in <FIG>, the server <NUM> is provided outside the hybrid vehicle <NUM>" and is provided with a communication interface <NUM>, a storage device <NUM>, a memory <NUM>, and a processor <NUM>. Note that the server <NUM> may further be provided with input devices such as a keyboard and a mouse, output devices such as a display, etc. Further, the server <NUM> may be constituted by a plurality of computers.

The communication interface <NUM> is capable of communicating with the hybrid vehicle <NUM>" and enables the server <NUM> to communicate with the hybrid vehicle <NUM>". Specifically, the communication interface <NUM> has an interface circuit for connecting the server <NUM> to a communication network <NUM>. The server <NUM> communicates with the hybrid vehicle <NUM>" through the communication interface <NUM>, the communication network <NUM>, and a wireless base station <NUM>.

The storage device <NUM> has, for example, a hard disk drive (HDD), a solid state drive (SSD), an optical recording medium, etc. The storage device <NUM> stores various data and stores, for example, computer programs by which the processor <NUM> executes various processing.

The memory <NUM> has, for example, a semiconductor memory such as a random access memory (RAM). The memory <NUM> stores, for example, various data to be used when various processing are executed by the processor <NUM>.

The communication interface <NUM>, the storage device <NUM>, and the memory <NUM> are connected to the processor <NUM> through signal wires. The processor <NUM> has one or more CPUs and peripheral circuits therefor and executes various processing. Note that the processor <NUM> may further have a processing unit such as a logic unit or an arithmetic unit.

In the fourth embodiment, the hybrid vehicle <NUM>" is provided with a communication module <NUM>. The communication module <NUM> is a device enabling communication between the hybrid vehicle <NUM>" and the outside of the hybrid vehicle <NUM>" (for example, the server <NUM>). The communication module <NUM> is, for example, a data communication module (DCM) capable of communication with the communication network <NUM> through the wireless base station <NUM>.

<FIG> is a view schematically showing the configuration of the position estimation system <NUM>" according to the fourth embodiment of the present invention. The position estimation system <NUM>" comprises an imaging device 11a, a GNSS receiver <NUM>, a map database <NUM>, a navigation device <NUM>, sensors <NUM>, a communication module <NUM>, and an ECU <NUM>. The imaging device 11a, the GNSS receiver <NUM>, the map database <NUM>, the navigation device <NUM>, the sensors <NUM>, and the communication module <NUM> are provided in the hybrid vehicle <NUM>" and are connected to the ECU <NUM> to be able to communicate through an internal vehicle network based on the CAN or other standard. Note that the communication module <NUM> may be assembled into the navigation device <NUM>.

In the fourth embodiment, the position estimating part26 receives position information of the hybrid vehicle <NUM>" from the server <NUM>. For example, position information for low emission zones is stored in the storage device <NUM> of the server <NUM>. The server <NUM> receives the position of the hybrid vehicle <NUM>" from the hybrid vehicle <NUM>" and transmits information regarding whether the position of the hybrid vehicle <NUM>" is within a low emission zone to the hybrid vehicle <NUM>".

As explained above, if a predetermined condition is satisfied and the object identified by the identifying part <NUM> is a sign indicating a boundary of a low emission zone, the position estimating part <NUM> judges whether the hybrid vehicle <NUM>" is located within a low emission zone, regardless of the output of the GNSS receiver <NUM>, based on the result of identification from the identifying part <NUM>. In the fourth embodiment, the predetermined condition includes communication between the hybrid vehicle <NUM>" and the server <NUM> being interrupted.

In the fourth embodiment, in the same way as the first embodiment, the control routine of the position estimation processing of <FIG> is executed. At this time, the predetermined condition of step S102 includes, in addition to or in place of the above-explained condition relating to the first embodiment, the condition that communication between the hybrid vehicle <NUM>" and the server <NUM> is interrupted.

Above, preferred embodiments according to the present invention were explained, but the present invention is not limited to these embodiments. Various modifications and changes can be made within the language of the claims.

For example, the portable terminal (for example, a smartphone, a tablet terminal, a laptop, etc.) electrically connected to the hybrid vehicle <NUM>, <NUM>', <NUM>" may have the functions of the GNSS receiver <NUM>, the map database <NUM>, and the navigation device <NUM>.

Further, the charging port <NUM> and the charger <NUM> may be omitted from the hybrid vehicle <NUM>, <NUM>', <NUM>". That is, the hybrid vehicle <NUM>, <NUM>', <NUM>" may be a type of hybrid vehicle for which the battery <NUM> is not charged by an external power source. Further, while the hybrid vehicle <NUM> shown in <FIG> is a so-called series-parallel type of hybrid vehicle, the hybrid vehicle <NUM>, <NUM>', <NUM>" may be a series type, a parallel type, or other type of hybrid vehicle so long as the hybrid vehicle can drive without operating the internal combustion engine.

Further, the embodiments explained above can be carried out in any combination. For example, if the second embodiment and the third embodiment are combined, in the control routine of <FIG>, step S302 of <FIG> is performed between step S202 and step S203. The predetermined condition of step S203 includes the reliability calculated by the reliability calculating part <NUM> being equal to or less than the reference value.

Claim 1:
A position estimation system (<NUM>, <NUM>', <NUM>") for estimating a position of a hybrid vehicle (<NUM>, <NUM>', <NUM>") comprising an internal combustion engine (<NUM>), an electric motor (<NUM>), and a battery (<NUM>), comprising:
a GNSS receiver (<NUM>);
an object detection device for detecting an object in surroundings of the hybrid vehicle (<NUM>, <NUM>', <NUM>"),
wherein the object detection device is an imaging device (11a) configured to capture an outside the hybrid vehicle (<NUM>, <NUM>") and generate an image;
an identifying part (<NUM>) configured to identify the object detected by the object detection device; and
a position estimating part (<NUM>) configured to estimate a position of the hybrid vehicle (<NUM>, <NUM>', <NUM>") based on an output of the GNSS receiver (<NUM>), wherein
if a predetermined condition is satisfied and the object identified by the identifying part (<NUM>) is a sign indicating a boundary of a low emission zone which requires that the internal combustion engine (<NUM>) be stopped, the position estimating part (<NUM>) is configured to judge whether the hybrid vehicle (<NUM>, <NUM>', <NUM>") is located within the low emission zone, regardless of the output of the GNSS receiver (<NUM>), based on a result of identification by the identifying part (<NUM>),
wherein the predetermined condition includes:
a current driving environment of the hybrid vehicle (<NUM>, <NUM>") not being a predetermined driving environment in which the precision of detection by the imaging device (11a) worsens; and
the hybrid vehicle (<NUM>, <NUM>', <NUM>") being located in a vicinity of the low emission zone, wherein the hybrid vehicle is located in the vicinity of the low emission zone if a shortest distance between the position of the hybrid vehicle estimated based on the output of the GNSS receiver (<NUM>) and the low emission zone within a predetermined time up to the present is equal to or less than a predetermined distance.