Patent ID: 12233879

DETAILED DESCRIPTION

It is desirable that a vehicle, such as an automobile, detects in-vehicle objects, such as occupants and baggage, inside the vehicle cabin, and monitors the states thereof.

In particular, when the vehicle is to travel in an automated driving mode, the state of each in-vehicle object in the vehicle cabin is to be monitored during the automated driving mode.

In JP-A No. 2020-101415 and JP-A No. 2020-142718, a radio wave, such as a millimeter wave, is radiated, and a reflection wave thereof is detected, whereby the state of each occupant is detected.

Furthermore, JP-A No. 2020-142718 discloses a function for detecting an infant left behind unattended in a vehicle.

However, when a millimeter radio wave is used in this manner to determine the type of in-vehicle object, such as either of an occupant and baggage, inside the vehicle cabin of the vehicle based on the detection level of a millimeter reflection wave, the reflection-wave detection level is not necessarily clearly divided for each type of in-vehicle object. Thus, it may possibly be difficult to accurately determine the type of the detected in-vehicle object. In particular, the difference between the detection level of a millimeter reflection wave from a child including an infant and the detection level of a millimeter reflection wave from baggage basically tends to be small. Because the detection level of a millimeter reflection wave from an occupant, such as an adult, is basically higher than the detection level of a millimeter reflection wave from baggage, a clear distinction is possible. However, the detection level of a millimeter reflection wave from a child, such as an infant, may sometimes be lower than the detection level of a millimeter reflection wave from baggage. For example, the detection level of a millimeter reflection wave from transparent-liquid-containing baggage, such as a plastic bottle containing a liquid, may sometimes be higher than the detection level of a millimeter reflection wave from a child, such as an infant. In this case, depending on the set threshold value, the plastic bottle containing the liquid may erroneously be determined to be a child, or the possibility of the child being erroneously determined to be baggage may increase if the threshold value is increased for preventing the erroneous determination.

Accordingly, in the vehicle, it is desirable to enhance the accuracy with respect to the determination of the type of in-vehicle object based on a detection result of the vehicle cabin obtained by using a millimeter radio wave.

In the following, an embodiment of the disclosure is described in detail with reference to the accompanying drawings. Note that the following description is directed to an illustrative example of the disclosure and not to be construed as limiting to the disclosure. Factors including, without limitation, numerical values, shapes, materials, components, positions of the components, and how the components are coupled to each other are illustrative only and not to be construed as limiting to the disclosure. Further, elements in the following example embodiment which are not recited in a most-generic independent claim of the disclosure are optional and may be provided on an as-needed basis. The drawings are schematic and are not intended to be drawn to scale. Throughout the present specification and the drawings, elements having substantially the same function and configuration are denoted with the same numerals to avoid any redundant description.

FIG.1is a plan view schematically illustrating an automobile1to which an unattended-occupant determination apparatus according to an embodiment of the disclosure is applied.FIG.2is a vertical sectional view schematically illustrating the automobile1inFIG.1. The vertical sectional view inFIG.2illustrates the automobile1inFIG.1and is taken along a center position Y0in the vehicle-width direction of the automobile1.

The automobile1is an example of a vehicle. A power source of the automobile1may be any one of an internal combustion engine that burns either of gasoline and ethanol, an electric motor that uses stored electric power, a power source that uses hydrogen, and a combination of the above.

The automobile1illustrated inFIG.1andFIG.2has a vehicle body2. The vehicle body2has a vehicle cabin (vehicle compartment)3that can accommodate a plurality of occupants. The vehicle cabin3is provided with a plurality of seats4to6disposed in the front-rear direction of the automobile1. In the following order from the front, the plurality of seats4to6in the automobile1inFIG.1are front-row seats4and5in which a driver11and a passenger12can sit, and a rear-row seat6in which a plurality of occupants can sit side-by-side in the vehicle-width direction of the automobile1. In this case, the front-row seats4and5serve as the front-most seats, and the rear-row seat6serves as the rear-most seat. A trunk7is provided behind the rear-row seat6.

The driver11enters the vehicle cabin3by opening and closing a right-front door (not illustrated) and sits in the driver seat4in the front row, and exits from the vehicle cabin3by opening and closing the right-front door.

The passenger12enters the vehicle cabin3by, for example, opening and closing a left-front door (not illustrated) and sits in the passenger seat5in the front row, and exits from the vehicle cabin3by opening and closing the left-front door.

A child13enters the vehicle cabin3by, for example, opening and closing either one of a right-rear door (not illustrated) and a left-rear door (not illustrated) and sits in the rear-row seat6, and exits from the vehicle cabin3by opening and closing either one of the right-rear door and the left-rear door. When assisting, for example, an infant, an adult, such as either one of the driver11and the passenger12, opens and closes either one of the right-rear door and the left-rear door, fastens a child seat14to the rear-row seat6, and sets the infant in the child seat14. Alternatively, the child13may sit in the passenger seat5in the front row. The passenger12may sit in the rear-row seat6.

The adults and the child13directly sitting in the seats4to6fasten seatbelts (not illustrated). Accordingly, the occupants sit in the seats4to6in a state where they rest their upper bodies on the backrests of the seats4to6. The seated position of each occupant sitting in the corresponding one of the seats4to6is basically within a fixed range.

In the state where the occupants including the driver11and the passenger12on board are sitting in the seats4to6in the vehicle cabin3, the automobile1travels in accordance with any one of a driving operation by the driver11, a driving support mode, and an automated driving mode.

In such an automobile1, for example, there have been studies with regard to monitoring the occupants11to13including the driver11in the vehicle cabin3while the automobile1is traveling, and executing control for providing an emergency notification and performing emergency stoppage if there is a state of emergency in any of the occupants.

Furthermore, in such an automobile1, there have been studies with regard to outputting an alarm if either of the child13and baggage is left behind unattended in the vehicle cabin3after an adult, such as the driver11, exits from the automobile1.

FIG.3illustrates a control system20serving as a vehicle-interior monitoring apparatus in the automobile1inFIG.1.

The control system20of the automobile1serves as a vehicle-interior monitoring apparatus that can detect and monitor in-vehicle objects, such as an occupant and baggage, in the vehicle cabin3.

The control system20inFIG.3has an in-vehicle-object determination device21, a movement sensor22, a door sensor23, a wireless communication device24, a user interface (UI) device25, and an in-vehicle network26to which these devices are coupled.

The in-vehicle network26may be a wired communication network compliant with, for example, a local interconnect network (LIN) or a controller area network (CAN) for the automobile1. The in-vehicle network26may be a communication network, such as a local area network (LAN), or may be a combination of the above networks. The in-vehicle network26may partially include a wireless communication network.

The movement sensor22detects the movement of the automobile1. The movement sensor22may be, for example, an acceleration sensor. Alternatively, the movement sensor22may be configured to predict and detect the movement of the automobile1by detecting, for example, an operation performed by the driver11, an output from the power source, the braking state of a braking device, and the steering state of a steering device. The movement sensor22supplies detection data about the latest movement of the automobile1at the current time point to each unit of the automobile1via the in-vehicle network26.

The door sensor23detects whether a plurality of doors (not illustrated) provided in the automobile1are opened or closed. The door sensor23may be provided for each of the openable-closable doors, such as the right-front door, the left-front door, the right-rear door, the left-rear door, and a hatchback door at the rear side of the vehicle body2. When the door sensor23detects that any of the doors provided in the automobile1is opened or closed, the door sensor23supplies the detection data to each unit of the automobile1via the in-vehicle network26. Accordingly, the door sensor23detects whether each door of the automobile1is opened or closed when an occupant exits from the automobile1.

In addition to operating the door when exiting from the automobile1, the occupant may operate the seatbelt and the ignition switch, and also hold and detach the key. The detection of the occupant exiting from the automobile1is possible by using, for example, a pressure sensor provided in the seat4, an operation sensor of the steering wheel, and a vehicle-interior monitoring device equipped with a monitoring camera.

The wireless communication device24establishes a wireless communication path with a wireless-communication base station (not illustrated) provided outside the automobile1, and exchanges data with the base station. Examples of the wireless-communication base station include a commercial-mobile-communication base station and a base station for exchanging traffic information. The base station is coupled to a server. The wireless communication device24may exchange data, via the base station or directly, with a user terminal29used by, for example, an occupant. In order to directly exchange data with the user terminal29, the wireless communication device24may be configured to perform communication compliant with either of the IEEE 802.11 standard and the IEEE 802.15 standard. The control system20of the automobile1may be equipped with a plurality of wireless communication devices24for the respective communication standards. When the wireless communication device24acquires transmission data from each unit of the automobile1via the in-vehicle network26, the wireless communication device24transmits the transmission data to the base station and the user terminal29. When the wireless communication device24receives reception data from the base station and the user terminal29, the wireless communication device24supplies the reception data to each unit of the automobile1via the in-vehicle network26.

The user interface device25is coupled to, for example, a liquid crystal device, a touchscreen device, various switches, a loudspeaker27, and a microphone28that are provided in the vehicle cabin3of the automobile1. The liquid crystal device may be provided as, for example, a meter panel provided in a dashboard in the vehicle cabin3and located in front of the driver11. The touchscreen device may be provided as, for example, a center display provided in the dashboard in the vehicle cabin3and located at the center in the vehicle-width direction. When the user interface device25acquires output data from each unit of the automobile1via the in-vehicle network26, the user interface device25outputs the output data from the liquid crystal device serving as a meter panel, the touchscreen device serving as a center display, and the loudspeaker27. Accordingly, each occupant can ascertain information about the automobile1through the user interface device25. Furthermore, when either of the touchscreen device and a switch is operated or when a predetermined voice is input to the microphone28, the user interface device25supplies the input data to each unit of the automobile1via the in-vehicle network26.

The in-vehicle-object determination device21is configured to monitor each occupant and baggage in the vehicle cabin3. The in-vehicle-object determination device21has a detection controller39, an output controller37, an input controller38, an input-output unit44, a timer43, a memory42, a central processing unit (CPU)41, and an internal bus45to which the above units are coupled. The units in the in-vehicle-object determination device21are capable of receiving and outputting data from and to one another via the internal bus45.

The output controller37is coupled to a first output antenna31and a second output antenna32. The output controller37individually controls output of a detection radio wave with a millimeter-wave frequency from the first output antenna31and output of a detection radio wave with a millimeter-wave frequency from the second output antenna32. The two-channel millimeter detection radio waves may be output at different output timings or may be output simultaneously. The millimeter detection radio waves may be temporally continuous or discontinuous radio waves. The millimeter detection radio waves may have different encoding data superimposed thereon between the first output antenna31and the second output antenna32.

The input controller38is coupled to a first input antenna33, a second input antenna34, a third input antenna35, and a fourth input antenna36. With regard to the input controller38, the first input antenna33, the second input antenna34, the third input antenna35, and the fourth input antenna36each receive a reflection wave reflected by a baggage object with respect to a millimeter detection radio wave. The input controller38monitors and controls input of the reflection wave to the first input antenna33, input of the reflection wave to the second input antenna34, input of the reflection wave to the third input antenna35, and input of the reflection wave to the fourth input antenna36. The millimeter detection radio waves output with two channels may be received with four channels by the four antennas. Each input antenna receives the reflection wave at a timing according to the distance from the output antenna serving as the output source to the reflective baggage and the distance from the reflective baggage to the input antenna. The distance and the direction of the reflective baggage with reference to these antennas are uniquely identifiable three-dimensionally by basically causing at least three input antennas to receive reflection waves from the same reflective baggage. However, there is a possibility that one input antenna may simultaneously receive a plurality of reflection waves reflected by pieces of reflective baggage located in a plurality of directions. For example, by combining two-channel output and four-channel input, it is possible to calculate the distance to the reflective baggage for each direction by separating a reflection wave component in each direction from a combined wave having a mixture of a plurality of reflection waves. The spatial resolution to be used for detecting a plurality of occupants in the vehicle cabin3may be ensured in accordance with, for example, the encoding data to be superimposed on the detection radio waves and the timing control.

The detection controller39controls the output of two-channel millimeter detection radio waves by the output controller37and the input of four-channel reflection waves by the input controller38. In addition to performing timing control between the output controller37and the input controller38, the detection controller39may set the frequencies of millimeter detection radio waves to be output from the first output antenna31and the second output antenna32under the control of the output controller37. A millimeter wave used is not limited to having a low frequency of about 24 GHz, and may have a high frequency of 60 to 78 GHz. The detection controller39may select one frequency from a plurality of frequencies, such as 24 GHz, 60 GHz, and 72 GHz, and set the selected frequency in the output controller37. When the frequency is set, the output controller37executes control for outputting millimeter detection radio waves having the set frequency from the first output antenna31and the second output antenna32.

Accordingly, the output controller37, the first output antenna31, the second output antenna32, the input controller38, the first input antenna33, the second input antenna34, the third input antenna35, the fourth input antenna36, and the detection controller39may each serve as a millimeter-wave sensor that outputs a millimeter radio wave toward the vehicle cabin3of the automobile1and detects a reflection wave from, for example, an occupant in the vehicle cabin3of the automobile1.

The input-output unit44is coupled to the in-vehicle network26. The input-output unit44exchanges data with each unit of the automobile1via the in-vehicle network26.

The timer43measures a time period and a time point. For example, the timer43may measure cyclic timings for outputting detection radio waves and a time period elapsed from each output timing of a detection radio wave.

The memory42stores a program to be executed by the CPU41, data to be used for executing the program, and data to be generated as a result of executing the program. The memory42may be constituted of a nonvolatile memory, such as a RAM, and a nonvolatile memory, such as either one of a solid state drive (SSD) and a hard disk drive (HDD).

The CPU41reads the program from the memory42and executes the program. Accordingly, in the in-vehicle-object determination device21, a controller that controls the overall operation thereof is realized. The CPU41may be, for example, any one of an electronic control unit (ECU), a microcomputer, and an application-specific integrated circuit (ASIC), so long as the CPU41has a computing function for executing the program.

For example, the CPU41serving as a controller may perform a monitoring process by determining the presence or absence and the type of in-vehicle object, such as either of an occupant and baggage, in the vehicle cabin3based on the detection level of a reflection wave of a millimeter detection radio wave.

In this case, the CPU41serving as a controller may select the frequency of the millimeter detection radio wave from a plurality of frequencies set in advance, and command the detection controller39to set the selected frequency. The radio-wave frequency that the CPU41can command the detection controller39to set may include a plurality of frequencies including a first frequency, such as 60 GHz, and a second frequency, such as 24 GHz, lower than the first frequency. In this case, the detection controller39executes a setting process in response to the command given by the CPU41and changes the frequency of the millimeter detection radio wave.

The CPU41serving as a controller may additionally serve as, for example, a determiner that detects an in-vehicle object, such as either of an occupant and baggage, in the vehicle cabin3of the automobile1and monitors the detected in-vehicle object. In this case, the CPU41may determine the type of in-vehicle object in the vehicle cabin3of the automobile1in accordance with a comparison between a threshold value and the detection level of a millimeter reflection wave detected by the input controller38.

For example, when an adult occupant, such as the driver11, exits from the automobile1, the CPU41serving as a controller may determine whether either of the child13and baggage is left behind unattended in the vehicle cabin3. Then, if either of the child13and baggage is left behind unattended in the vehicle cabin3of the automobile1, the CPU41may output an alarm to the occupant from, for example, the liquid display device serving as a meter panel, the touchscreen device serving as a center display, and the loudspeaker27via the user interface device25. The CPU41may also output an alarm to the user terminal29, used by the occupant, via the wireless communication device24.

As illustrated inFIG.1, the in-vehicle-object determination device21having the millimeter-wave sensors31to39are provided at the center position Y0in the vehicle-width direction of the automobile1and are disposed at the front edge of the ceiling in the vehicle cabin3of the automobile1. The in-vehicle-object determination device21having the millimeter-wave sensors31to39are provided at the position of the so-called overhead console. The in-vehicle-object determination device21outputs a millimeter detection radio wave mainly rearward and downward toward the entire vehicle cabin3from the installed location of the in-vehicle-object determination device21. Accordingly, the in-vehicle-object determination device21having the millimeter-wave sensors31to39is provided facing rearward and downward from an upper-front position located forward of the seat-backs of all the seats4to6provided in the vehicle cabin3. Consequently, a millimeter detection radio wave can be output toward the front surface of the chest of each of the occupants sitting in the seats4to6. The central direction in which the in-vehicle-object determination device21mainly outputs a radio wave may at least be the rearward direction.

Furthermore, in the in-vehicle-object determination device21provided at the position of the overhead console, the first output antenna31and the second output antenna32may be separated from each other by a predetermined distance and be provided parallel to, for example, either of the vehicle-width direction and the front-rear direction. For example, the first input antenna33, the second input antenna34, the third input antenna35, and the fourth input antenna36may be disposed at the four corners of a rectangle whose four sides extend in the vehicle-width direction and the front-rear direction.

FIG.4is a diagram of a first detection state for explaining the detection principle of the millimeter-wave sensors31to39used in the in-vehicle-object determination device21inFIG.3. In the first detection state, there is no occupant or baggage in the seat4.

FIG.4illustrates one seat4and the in-vehicle-object determination device21provided at the front-upper side of the seat4. The in-vehicle-object determination device21outputs a millimeter detection radio wave having the set frequency from an output antenna, such as either one of the first output antenna31and the second output antenna32.

InFIG.4, there is no in-vehicle object, such as either of an occupant and baggage, in the seat4. Therefore, the millimeter detection radio wave to be output rearward and downward from the in-vehicle-object determination device21toward the seat4passes through the seat4. The seat4basically has springs set in the seat frame and is entirely covered with urethane and cloth. The seat4with such a structure and material hardly reflects a millimeter detection radio wave. As a result, the in-vehicle-object determination device21does not receive a reflection wave from the seat4.

FIG.5is a diagram of a second detection state in which an occupant is sitting in the seat4inFIG.4.FIG.5illustrates one seat4, the in-vehicle-object determination device21provided at the front-upper side of the seat4, and the occupant sitting in the seat4.

In this case, since the occupant is sitting in the seat4, a millimeter detection radio wave output from an output antenna, such as either one of the first output antenna31and the second output antenna32, may be reflected at the surface of the occupant. A millimeter reflection wave from the occupant returns toward the in-vehicle-object determination device21. The plurality of input antennas33to36of the in-vehicle-object determination device21receive the millimeter reflection wave. The in-vehicle-object determination device21can detect a reflection wave stronger than that inFIG.4.

FIG.6illustrates a three-dimensional vehicle-cabin detection map50that can be generated based on the detection by the millimeter-wave sensors31to39in the second detection state inFIG.5.

FIG.6illustrates the seat4and a reflective surface51detected with respect to the occupant sitting in the seat4. The CPU41of the in-vehicle-object determination device21uses two-channel output and four-channel input in combination with each other to separate a reflection wave component in each direction from an input wave having a mixture of a plurality of reflection waves, thereby calculating the distance to reflective baggage for each direction. In this case, the CPU41of the in-vehicle-object determination device21may vary the output timings of millimeter-wave detection signals from the plurality of output antennas or may vary the detection periods and timings of the millimeter waves from the plurality of input antennas33to36. As a result, the CPU41of the in-vehicle-object determination device21obtains the distance for each input direction of a reflection wave with reference to the installed location of the in-vehicle-object determination device21, thereby generating a vehicle-cabin detection map50indicating the shape and size of the three-dimensional reflective surface51, as indicated with a solid line inFIG.6, extending along the surface of the occupant.

If respiratory movement on the chest surface of the occupant sitting stably in the seat4is to be detected based on a millimeter reflection wave, the vehicle-cabin detection map50is to temporally contain a movement component of the reflective surface. In this case, instead of having a low frequency of, for example, about 24 GHz, the millimeter wave used may belong to a high frequency range, such as a frequency of 50 GHz or higher, preferably, 60 to 78 GHz. By using a high-frequency millimeter wave as a detection radio wave, a temporally-fluctuating component of the chest surface caused by respiration may be observed in the vehicle-cabin detection map50. By using a high-frequency millimeter detection radio wave, high spatial resolution that enables detection of the respiratory movement on the chest surface of the occupant present in the vehicle cabin3of the automobile1can be obtained in the vehicle-cabin detection map50.

On the other hand, if a vehicle-cabin detection map50covering a wide detection range throughout the entire vehicle cabin3of the automobile1is to be obtained, a millimeter wave with a low frequency of 24 GHz or lower may be used. A millimeter detection radio wave with a low frequency, such as 24 GHz, does not enable highly-accurate detection of the chest-surface movement of the occupant or the size and shape of an in-vehicle object, as in the case where a high frequency is used, but tends to travel around the baggage to reach behind the baggage and is thus immune against being blocked. When a millimeter detection radio wave with a high frequency of 60 GHz or higher is used, for example, it is not easy for the millimeter detection radio wave to effectively reach the rear side of a seat-back containing a metal sheet or the left and right edges of the vehicle cabin3in the vehicle-width direction. If an in-vehicle object is present in an area that the millimeter detection radio wave is not effectively reachable, it is difficult to obtain a significant reflection wave from the in-vehicle object. The seat-back of the rearmost seat, such as the rear-row seat6inFIG.1, located in front of the trunk7has a metal sheet over the entire width in the vehicle-width direction of the automobile1.

Therefore, in this embodiment, the frequency of the millimeter wave to be used as a detection radio wave is used in a switching manner between at least two frequencies, that is, a high frequency and a low frequency. This description relates to a case where 60 GHz and 24 GHz are used.

In this embodiment, in order to use the frequency of the millimeter wave in a switching manner, the entire vehicle cabin3can be thoroughly detected with high resolution by simply providing a single in-vehicle-object determination device21in the vehicle cabin3of the automobile1. Thus, the vehicle cabin3of the automobile1is not to be provided with a plurality of in-vehicle-object determination devices21in correspondence with the plurality of seats4to6. The number of in-vehicle-object determination devices21is reduced to a minimum, so that an increase in cost involved in using a millimeter wave for monitoring, for example, occupants can be suppressed. In addition, since the number of in-vehicle-object determination devices21is reduced, excessive limitations with regard to the disposition of various devices including the in-vehicle-object determination device21in the vehicle cabin3do not occur.

FIG.7is a flowchart of a millimeter-wave detection control process executed by the CPU41of the in-vehicle-object determination device21inFIG.3.

The CPU41of the in-vehicle-object determination device21repeatedly executes the process inFIG.7.

The CPU41may repeatedly execute the process inFIG.7for every detection period measured by the timer43.

In step ST1, the CPU41selects the frequency of a millimeter detection radio wave to be used for detecting an in-vehicle object, such as either of an occupant and baggage, present in the vehicle cabin3from a plurality of frequency candidates, such as 60 GHz and 24 GHz.

During a normal mode, such as when the automobile1is traveling, the CPU41may select the high frequency of 60 GHz to enable detection of the respiratory movement on the chest surface of the occupant present in the vehicle cabin3.

If in-vehicle objects, such as the child13and baggage, left behind unattended are to be detected, the CPU41may select the low frequency of 24 GHz to enable detection throughout the vehicle cabin3.

In step ST2, the CPU41causes each of the first output antenna31and the second output antenna32to output a millimeter detection radio wave having the selected frequency, and detects input of a millimeter reflection wave. The CPU41commands the output controller37to output a millimeter detection radio wave. The output controller37outputs the millimeter detection radio wave having the selected frequency from each of the first output antenna31and the second output antenna32. In this case, the output controller37may scan the vehicle cabin3by, for example, adjusting the interval between the output timing of the millimeter detection radio wave from the first output antenna31and the output timing of the millimeter detection radio wave from the second output antenna32.

If there are occupants sitting in the seats4to6in the vehicle cabin3or if there is baggage in the seats4to6or the trunk7, the millimeter detection radio wave is reflected by the occupants or the baggage. The reflection waves from the in-vehicle objects are input to the first input antenna33, the second input antenna34, the third input antenna35, and the fourth input antenna36of the in-vehicle-object determination device21. The input controller38generates information about the reflection wave input to the first input antenna33, information about the reflection wave input to the second input antenna34, information about the reflection wave input to the third input antenna35, and information about the reflection wave input to the fourth input antenna36, and outputs these pieces of information to the CPU41.

In step ST3, the CPU41generates a vehicle-cabin detection map50indicating the positions and ranges in the vehicle cabin3with respect to reflective surfaces of the in-vehicle objects, such as the occupants and the baggage, present in the vehicle cabin3based on the detection information about the reflection waves from the input controller38. With regard to the vehicle-cabin detection map50, the range of the vehicle cabin3indicated with a single-dot chain line inFIG.1may basically be the detection range using the reflection waves of the millimeter waves. The CPU41serves as a controller to generate the vehicle-cabin detection map50obtained as a result of the vehicle cabin3of the automobile1being detected based on the reflection waves reflected in the respective areas in the vehicle cabin3of the automobile1and detected by the millimeter-wave sensors31to39.

In step ST4, the CPU41stores the generated vehicle-cabin detection map50in the memory42together with information about a detection time point measured by the timer43. Accordingly, a plurality of vehicle-cabin detection maps50generated at different timings are stored in the memory42in correspondence with information about respective detection time points. The plurality of vehicle-cabin detection maps50contain information about temporal changes in the movement of the occupants and baggage in the vehicle cabin3.

FIG.8is a flowchart of a basic in-vehicle-object determination control process executed by the CPU41of the in-vehicle-object determination device21inFIG.3.

For example, the CPU41of the in-vehicle-object determination device21repeatedly executes the process inFIG.8every time the millimeter-wave detection control process inFIG.7is executed.

The CPU41may repeatedly execute the process inFIG.8for every detection period measured by the timer43.

In step ST11, the CPU41determines whether there is a new occupant or baggage on board the automobile1. For example, the CPU41may determine whether there is a new occupant or baggage on board the automobile1based on whether the door sensor23has detected that a door is newly opened or closed. If there is no new occupant or baggage on board, the CPU41determines that there is no new in-vehicle object on board, and repeats the process. If there is a new occupant or new baggage on board, the CPU41determines that there is a new in-vehicle object on board, and proceeds to step ST12.

In step ST12, the CPU41determines whether a new vehicle-cabin detection map50has been generated. For example, the CPU41may perform the determination based on whether a newly-generated vehicle-cabin detection map50is stored in the memory42. If a new vehicle-cabin detection map50is not generated, the CPU41repeats the process. If a new vehicle-cabin detection map50is generated, the CPU41proceeds to step ST13.

In step ST13, the CPU41estimates the in-vehicle object based on the new vehicle-cabin detection map50. The vehicle-cabin detection map50contains a component of the reflective surface of the occupant or baggage that has reflected the millimeter detection radio wave. The CPU41may estimate the in-vehicle object based on a differential component between the new vehicle-cabin detection map50and the vehicle-cabin detection map50corresponding to a case where, for example, there is no occupant or baggage whatsoever. The CPU41may estimate the size of the in-vehicle object from a range that includes the differential component in the vehicle-cabin detection map50. The CPU41may estimate the position of any of the seats4to6where the in-vehicle object that has caused the differential component to occur is present based on the position with respect to the range including the differential component with reference to the position of the in-vehicle-object determination device21. The CPU41may estimate the size and the position with respect to each of a plurality of in-vehicle objects present in the vehicle cabin3.

In step ST14, the CPU41determines whether the in-vehicle object has been detected. If even a single in-vehicle object is estimated in step ST13, the CPU41determines that there is an in-vehicle object and proceeds to step ST15. If not even a single in-vehicle object is estimated, the CPU41determines that there is no in-vehicle object and ends the control process.

Accordingly, the CPU41serves as a determiner that can perform determination based on the detection of a reflection wave by each of the millimeter-wave sensors31to39, and determine the presence or absence and the type of occupant present in the vehicle cabin3of the automobile1based on the vehicle-cabin detection map50of the automobile1.

In step ST15, the CPU41determines the type of in-vehicle object, that is, determines whether the in-vehicle object is either of a person (i.e., an occupant) and baggage.

In this determination between a person and baggage, for example, the CPU41may use detection levels in predetermined directions estimated as in-vehicle-object ranges in a plurality of vehicle-cabin detection maps50from a past vehicle-cabin detection map50to a new vehicle-cabin detection map50.

The body of an adult sitting in any of the seats4to6is closer to the millimeter-wave sensors31to39, as compared with the body of a child sitting in any of the seats4to6or baggage placed on any of the seats4to6. Therefore, the detection level of a millimeter reflection wave from an adult is higher than those of a child and baggage.

Furthermore, the body of a child sitting in any of the seats4to6is basically closer to the millimeter-wave sensors31to39, as compared with baggage placed on any of the seats4to6. Therefore, the detection level of a millimeter reflection wave from a child is higher than that of baggage.

Thus, for example, the CPU41compares the acquired detection level with a high threshold value that is lower than the adult detection level and higher than the child detection level. If the acquired detection level is higher than or equal to the high threshold value, the CPU41may determine that the in-vehicle object is an adult.

Moreover, for example, the CPU41compares the acquired detection level with a low threshold value that is lower than the child detection level and higher than the baggage detection level. If the acquired detection level is higher than or equal to the low threshold value, the CPU41may determine that the in-vehicle object is a child.

If the acquired detection level is lower than the low threshold value, the CPU41may determine that the in-vehicle object is baggage.

In step ST16, the CPU41generates information about the determined in-vehicle object and stores the information in the memory42. In the memory42, in-vehicle-object information about either of the occupant and baggage, determined based on at least the latest detection, on board the automobile1is stored for each in-vehicle object.

FIG.9illustrates a millimeter-wave detection-level distribution with respect to an occupant and baggage within the vehicle cabin3.

InFIG.9, the ordinate axis denotes the millimeter-wave detection level of each in-vehicle object, whereas the abscissa axis denotes three types of in-vehicle objects, namely, baggage, a child, and an adult.

As illustrated inFIG.9, the in-vehicle objects, such as baggage, a child, and an adult, within the vehicle cabin3each have a millimeter-wave detection-level distribution range.

For example, an adult in the vehicle cabin3reflects a millimeter wave at each body part, as illustrated inFIG.6. For example, the millimeter-wave detection level illustrated inFIG.9may have a maximum value for the reflection wave at each body part inFIG.6. It is conceivable that a millimeter-wave detection-level distribution range having the same tendency as inFIG.9can be obtained by using an average value or median value of the reflection wave at each part of an in-vehicle object.

An adult in the vehicle cabin3corresponds to a high detection level even when the adult is sitting in any of the seats4to6.

A child in the vehicle cabin3corresponds to a low detection level, as compared with an adult in the vehicle cabin3, even when the child is sitting in any of the seats4to6. The detection level of a millimeter reflection wave from an infant sleeping in a child seat disposed facing rearward in the rear-row seat6and the detection level of a millimeter reflection wave from an infant located at the bottom of the rear-row seat6tend to be the lowest in the child's distribution range.

Baggage in the vehicle cabin3basically corresponds to a low detection level even when the baggage is placed on either of the seats5and6. The detection level of a millimeter reflection wave from transparent-liquid-containing baggage, such as a plastic bottle containing a liquid, tends to be the highest in the baggage's distribution range.

As a result, the detection level of a millimeter reflection wave from baggage, such as a plastic bottle containing a liquid, inFIG.9may possibly be higher than the detection level of a millimeter reflection wave from a child, such as an infant.

If the detection-level distribution ranges of a plurality of types of in-vehicle objects overlap in this manner, it may possibly be difficult to accurately determine the type of in-vehicle object by simply comparing such a millimeter-wave detection level with a threshold value. It is not easy to enhance the accuracy with respect to the determination of the type of in-vehicle object.

Accordingly, a reflection-wave detection level is not necessarily clearly divided for each type of in-vehicle object. Thus, it may possibly be difficult to accurately determine the type of the detected in-vehicle object even by comparing the detection level with a plurality of threshold values.

In particular, the difference between the detection level of a millimeter reflection wave from a child including an infant and the detection level of a millimeter reflection wave from baggage basically tends to be small. Because the detection level of a millimeter reflection wave from an occupant, such as an adult, is basically higher than the detection level of a millimeter reflection wave from baggage, a clear distinction is possible. However, the detection level of a millimeter reflection wave from a child, such as an infant, may sometimes be lower than the detection level of a millimeter reflection wave from baggage. For example, the detection level of a millimeter reflection wave from transparent-liquid-containing baggage, such as a plastic bottle containing a liquid, may sometimes be higher than the detection level of a millimeter reflection wave from a child, such as an infant. In this case, depending on the set threshold value, the plastic bottle containing the liquid may erroneously be determined to be a child, or the possibility of the child being erroneously determined to be baggage may increase if the threshold value is increased for preventing the erroneous determination.

If the type of in-vehicle object is to be determined based on the detection result of the vehicle cabin3obtained by using a millimeter radio wave in this manner, it is demanded that the accuracy thereof be enhanced.

FIG.10is a flowchart of an in-vehicle-object-type re-determination control process executed by the CPU41of the in-vehicle-object determination device21inFIG.3.

For example, after the process inFIG.8, the CPU41of the in-vehicle-object determination device21may repeatedly execute the process inFIG.10as a process different from that inFIG.8every time the millimeter-wave detection control process inFIG.7is executed.

For example, after the process inFIG.8, the CPU41may repeatedly execute the process inFIG.10for every detection period measured by the timer43.

In step ST21, the CPU41determines whether the automobile1is traveling. The CPU41may determine whether the automobile1is traveling based on, for example, whether the movement sensor22of the automobile1is detecting the acceleration or speed thereof while the automobile1is traveling. If the automobile1is traveling, the CPU41proceeds to step ST22. If the automobile1is not traveling, the CPU41ends the control process.

In step ST22, the CPU41determines whether a detected in-vehicle object includes either of a child and baggage. For example, the CPU41may acquire in-vehicle-object information stored in the memory42as a result of the control process inFIG.8and determine whether the acquired in-vehicle-object information contains an attribute of either of a child and baggage. If the in-vehicle-object information contains an attribute of either of a child and baggage, the CPU41determines that the detected in-vehicle object includes either of a child and baggage, and proceeds to step ST23. If the in-vehicle-object information does not contain an attribute of either of a child and baggage, the CPU41determines that the detected in-vehicle object does not include either of a child and baggage, and ends the control process.

In step ST23, the CPU41determines whether a new vehicle-cabin detection map50is generated. If a new vehicle-cabin detection map50is not generated after the previous process inFIG.10, the CPU41repeats the current process. When a new vehicle-cabin detection map50is generated, the CPU41proceeds to step ST24.

In step ST24, the CPU41generates positional information of each detected in-vehicle object based on the new vehicle-cabin detection map50. The CPU41may estimate each in-vehicle object with respect to the vehicle-cabin detection map50and estimate the size and position of the in-vehicle object. The CPU41stores the generated positional information of each in-vehicle object in the memory42. Accordingly, the memory42accumulatively stores a plurality of pieces of positional information about the in-vehicle objects in a time-series fashion.

In step ST25, the CPU41determines the behavior of the automobile1. When the automobile1is traveling, the behavior thereof changes in accordance with steering and acceleration even during, for example, a normal traveling mode. The movement sensor22detects the behavior of the traveling automobile1. For example, the CPU41may determine that the automobile1is excessively steered or accelerated based on whether a detection value of the movement sensor22is larger than or equal to a predetermined value. If the automobile1is excessively steered or accelerated, the CPU41proceeds to step ST26. If the automobile1is not excessively steered or accelerated, the CPU41ends the control process.

In step ST26, the CPU41acquires positional information of each in-vehicle object prior to the occurrence of the excessive behavior of the automobile1, that is, prior to the change. The CPU41acquires, from the memory42, past positional information of each in-vehicle object prior to the occurrence of the excessive behavior of the automobile1. For example, the CPU41may acquire positional information stored prior to the latest positional information stored in the memory42.

In step ST27, the CPU41generates an amount of positional change of each detected in-vehicle object. The CPU41may calculate the amount of positional change after the behavior has occurred in step ST24with reference to the position acquired in step ST26.

In step ST28, the CPU41determines whether the generated amount of positional change of each in-vehicle object is larger than or equal to a predetermined amount. For example, the predetermined amount may be a value to an extent that baggage moves due to the behavior of the automobile1. If the amount of positional change of the in-vehicle object is larger than or equal to the predetermined amount, the CPU41determines that the in-vehicle object is baggage, and proceeds to step ST29. If the amount of positional change of the in-vehicle object is smaller than the predetermined amount, the CPU41determines that the in-vehicle object is a child, and proceeds to step ST30.

Accordingly, the CPU41serves as a determiner that can re-determine whether the in-vehicle object, having undergone the determination based on the detection level of a millimeter reflection wave, is either of a child and baggage based on the magnitude of a positional change of the in-vehicle object when the behavior of the automobile1greatly changes due to the movement of the automobile1detected by the movement sensor22. With reference to the position of the in-vehicle object prior to a change in the behavior of the automobile1due to the movement of the automobile1detected by the movement sensor22, the CPU41can re-determine that the in-vehicle object is baggage if the positional change of the in-vehicle object is larger than or equal to the predetermined amount, and re-determine that the in-vehicle object is a child if the positional change of the in-vehicle object is smaller than the predetermined amount.

In step ST29, the CPU41updates the in-vehicle-object information stored in the memory42to baggage.

In step ST30, the CPU41updates the in-vehicle-object information stored in the memory42to a child.

The following description relates to positional changes in a child sitting in the rear-row seat6and baggage placed thereon.

FIG.11illustrates positional changes in a child sitting in the rear-row seat6and baggage placed thereon before excessive behavior occurs in the automobile1. The seated position of the child is fixed by a seatbelt. The baggage is placed on the seat face of the seat6. Positional information containing the seated position of the child and positional information containing the placement position of the baggage in the state inFIG.11are stored in the memory42.

FIG.12illustrates positional changes in the child sitting in the rear-row seat6and the baggage placed thereon in a state where excessive behavior is occurring in the automobile1. InFIG.12, acceleration is generated leftward in the drawing. The movement sensor22detects this acceleration. The upper body of the child whose seated position is fixed by the seatbelt slightly leans in the direction of the acceleration due to this acceleration. The baggage moves in the direction of the acceleration due to this acceleration. The position of the baggage changes in accordance with excessive acceleration.

FIG.13illustrates positional changes in the child sitting in the rear-row seat6and the baggage placed thereon after excessive behavior has occurred in the automobile1. The position of the child, including the upper body thereof, whose seated position is fixed by the seatbelt has not changed from the position inFIG.11. In contrast, the position of the baggage has changed from the position inFIG.11.

The CPU41generates positional information about the child and positional information about the baggage based on the vehicle-cabin detection map50with respect to the state inFIG.13.

Then, since the amount of change in the positional information about the child is smaller than the predetermined amount, the CPU41updates the in-vehicle-object information stored in the memory42to a child in step ST30.

Furthermore, since the amount of change in the positional information about the baggage is larger than or equal to the predetermined amount, the CPU41updates the in-vehicle-object information stored in the memory42to baggage in step ST29.

Accordingly, for example, even if the baggage is erroneously determined to be a child based on the state inFIG.11, the in-vehicle-object information can be correctly updated to baggage.

Furthermore, for example, even if the child is erroneously determined to be baggage based on the state inFIG.11, the in-vehicle-object information can be correctly updated to a child.

FIG.14is a flowchart of an unattended-object monitoring control process executed by the CPU41of the in-vehicle-object determination device21inFIG.3.

The CPU41of the in-vehicle-object determination device21repeatedly executes the unattended-object monitoring control process inFIG.14.

In step ST41, the CPU41determines whether there is a new in-vehicle object boarding the automobile1from the rear side. The CPU41may determine whether there is a new occupant on board the rear-row seat6. It may be determined that a new occupant is on board the rear-row seat6based on, for example, detection of opening and closing of a door corresponding to the rear-row seat6. If there is no new occupant on board the rear-row seat6, the CPU41repeats the process. If there is a new occupant on board the rear-row seat6, the CPU41proceeds to step ST42.

In step ST42, the CPU41determines the type of in-vehicle object. The CPU41may execute either one of the in-vehicle-object type determination process inFIG.10and the in-vehicle-object type determination process inFIG.8. The CPU41determines that the type of in-vehicle object is any one of an adult, a child, and baggage. In addition to executing the in-vehicle-object type determination process with respect to the rear-row seat6, the CPU41may execute the in-vehicle-object type determination process with respect to all the seats including the front-row seats4and5. Moreover, the CPU41may execute the in-vehicle-object type determination process with respect to the trunk7.

In step ST43, the CPU41updates a boarding history in accordance with the determination result obtained from the in-vehicle-object type determination process in step ST42, and stores the updated boarding history in the memory42. If the CPU41has executed the in-vehicle-object type determination process with respect to the rear-row seat6alone in step ST42, the CPU41may add the determination result obtained in step ST42to the boarding history stored in the memory42. If the CPU41has executed the in-vehicle-object type determination process with respect to all the seats in step ST42, the CPU41may entirely overwrite the boarding history stored in the memory42based on the determination result obtained in step ST42. Accordingly, information indicating at least the latest on-board state of either of the occupant and baggage in the rear-row seat6is stored in the memory42. Alternatively, information indicating the latest on-board states of all the occupants and baggage in all the seats4to6and the trunk7may be stored in the memory42.

In step ST44, the CPU41determines whether the automobile1has completed traveling and stopped. For example, the CPU41may determine whether the automobile1has completed traveling and stopped based on whether the ignition switch (not illustrated) has been operated for stopping the power source after the traveling of the automobile1. When the driver11is to exit from the automobile1after traveling, the driver11is to operate the ignition switch. If the ignition switch is not operated after the traveling of the automobile1, the CPU41determines that the automobile1has not completed traveling and stopped, and returns to step ST41. The CPU41repeats the process from step ST41to step ST44until the CPU41determines that the automobile1has completed traveling and stopped. Accordingly, the information about the boarding history stored in the memory42may be updated in correspondence with the latest on-board state in the traveling mode. When the ignition switch is operated after the traveling of the automobile1, the CPU41determines that the automobile1has completed traveling and stopped, and proceeds to step ST47to start an unattended-object monitoring process.

In step ST45, the CPU41executes a process for re-determining the attribute of the in-vehicle object during the traveling of the automobile1. For example, the CPU41may execute the process inFIG.10for re-determining the attribute of the in-vehicle object.

In step ST46, the CPU41determines whether the automobile1has completed traveling. For example, if the automobile1has stopped such that the detection value of the movement sensor22corresponds to a stop, the CPU41may determine that the automobile1has completed traveling. If the automobile1has not completed traveling, the CPU41returns to step ST45. Accordingly, the memory42accumulatively stores information about each detected in-vehicle object at the time of boarding before the automobile1starts traveling in addition to information about each detected in-vehicle object during the traveling of the automobile1. The information corresponding to each time point contains positional information of each in-vehicle object. Furthermore, the determination of whether each in-vehicle object is either of a child and baggage may be updated, where appropriate, based on latest detection. When the automobile1has completed traveling, the CPU41proceeds to step ST47.

Accordingly, the CPU41serves as a determiner that compares the detection level of a millimeter reflection wave detected by each millimeter-wave sensor with a threshold value while the automobile1is stopped, so that the CPU41can determine whether there is an in-vehicle object in the vehicle cabin3of the automobile1and also determine that the type of in-vehicle object is any one of, for example, an adult, a child, and baggage. Moreover, when the behavior of the automobile1greatly changes due to the movement of the automobile1detected by the movement sensor22while the automobile1is traveling, the CPU41can repeat the in-vehicle-object-type re-determination process based on the magnitude of a positional change of the in-vehicle object. If the CPU41has determined that the in-vehicle object is either of a child and baggage in the determination process while the automobile1is stopped, the CPU41can repeat the determination process with respect to the in-vehicle object, determined to be either of a child and baggage, based on the magnitude of the positional change of the in-vehicle object when the behavior of the automobile1greatly changes due to the movement of the automobile1detected by the movement sensor22while the automobile1is traveling. As a result, in this embodiment, even when proper determination is difficult with the determination process executed at the time of boarding, it is expected that the accuracy with respect to the determination of the type of in-vehicle object may be enhanced with the determination process executed while the automobile1is traveling.

From step ST47, the CPU41starts executing the unattended-object monitoring process on either of a child and baggage after the automobile1has stopped. The CPU41first acquires the latest boarding history from the memory42.

In step ST48, the CPU41determines whether a child is left behind in the rear-row seat6based on the acquired boarding history. If an open-close history, obtained by the door sensor23, about a boarding door other than the front doors of the automobile1before the automobile1starts traveling is stored in the boarding history, the CPU41may determine that a child has possibly boarded the automobile1. The boarding history in the memory42may include a detection result that is obtained by a detector (not illustrated) other than the door sensor23and that indicates a plurality of kinds of operations performed when an occupant exits from the automobile1. If the boarding history with respect to the rear-row seat6includes a child, the CPU41determines that a child is left behind in the rear-row seat6and proceeds to step ST49. If the boarding history with respect to the rear-row seat6does not include a child, the CPU41determines that a child is not left behind in the rear-row seat6and ends the control process.

In step ST49, the CPU41outputs a meter alarm. The CPU41causes the liquid display device serving as a meter panel to display an unattended-child alarm screen via the user interface device25. The driver11can recognize a possibility of the child being left behind unattended based on the display on the meter panel that changes in response to an operation performed on the ignition switch when an occupant exits from the automobile1. By determining that the child is left behind unattended based on the boarding history prior to an exit from the automobile1and outputting the alarm in this manner, a possibility of the child being left behind unattended can be recognized from the alarm even if the child is not properly sitting in the rear-row seat6at the time of the exit, such as when the child is lying down at the bottom of the rear-row seat6or is sleeping in the child seat14. In this case, the liquid crystal device serving as a meter panel serves as an alarm unit that outputs an alarm to an occupant of the automobile1. If the child in the vehicle cabin3is detected when the occupant exits from the automobile1, the liquid crystal device serving as a meter panel can output an alarm indicating that the child is left behind unattended to the occupant, such as the driver11, exiting from the automobile1. If the child in the vehicle cabin3is not detected when the occupant exits from the automobile1, the liquid crystal device serving as a meter panel does not output the alarm.

In step ST50, the CPU41determines whether the doors of the automobile1have been locked in addition to determining whether the occupant has exited from the front side. The occupant exits from the automobile1by opening and closing the door. When the occupant moves away from the automobile1, the doors are automatically locked. If the occupant has not exited from the automobile1from the front side or if the occupant exited from the automobile1has not moved away from the automobile1and the doors are not locked, the CPU41repeats this determination process. When the occupant moves away from the automobile1after exiting from the front side and the doors are locked, the CPU41proceeds to step ST51based on these plurality of kinds of operations performed when the occupant exits from the automobile1.

In step ST51, the CPU41executes the in-vehicle-object type process inFIG.10. The CPU41determines that the type of in-vehicle object is any one of an adult, a child, and baggage based on the detection level.

In this case, the CPU41determines that the type of in-vehicle object is either of a child and baggage based on a temporal change in the detection level. In detail, with reference to a detection-level variation immediately after the boarding process, the CPU41serves as a determiner that determines that the in-vehicle object is baggage if the detection level of a millimeter reflection wave detected by each of the millimeter-wave sensors31to39temporally decreases to a predetermined amount or more as compared with the detection-level variation immediately after the boarding process in a state where the automobile1has stably stopped, and then becomes stable in the decreased state below the detection-level variation immediately after the boarding process. Furthermore, with reference to the detection-level variation immediately after the boarding process, if the detection level of a millimeter reflection wave detected by each of the millimeter-wave sensors31to39has become stable in the detection-level variation immediately after the boarding process without decreasing to the predetermined amount or more in a state where the automobile1has stably stopped even after some time has elapsed, the CPU41determines that the in-vehicle object is a child.

In addition to executing the in-vehicle-object type determination process with respect to the rear-row seat6, the CPU41may execute the process with respect to all the seats including the front-row seats4and5. Moreover, the CPU41may execute the in-vehicle-object type determination process with respect to the trunk7.

In step ST52, the CPU41determines whether a child is left behind in the rear-row seat6based on the determination result obtained in step ST51. If a child is detected in the rear-row seat6, the CPU41determines that the child is left behind in the rear-row seat6and proceeds to step ST53. If a child is not detected in the rear-row seat6, the CPU41determines that a state where a child is left behind unattended in the rear-row seat6has already been canceled, and ends the control process.

In step ST53, the CPU41outputs a horn alarm. The CPU41causes the loudspeaker27to output an alarm sound indicating that the child is left behind unattended via the user interface device25. An occupant, such as the driver11, exiting from the automobile1can recognize a possibility of the child being left behind unattended based on the alarm sound output in response to locking of the doors during the exit. By determining that the child is left behind unattended based on the determination of the type of in-vehicle object actually detected after the exit and outputting the alarm in this manner, a possibility of the child being left behind unattended can be recognized from the alarm even if the child is not properly sitting in the rear-row seat6at the time of the exit, such as when the child is lying down at the bottom of the rear-row seat6or is sleeping in the child seat14. If it is determined that the child is left behind in the vehicle cabin3when the occupant exits from the automobile1, the loudspeaker27can output an alarm indicating that the child is left behind unattended to the occupant, such as the driver11, exiting from the automobile1. If the child in the vehicle cabin3is not detected when the occupant exits from the automobile1, the loudspeaker27does not output the alarm.

In step ST54, the CPU41determines whether a predetermined time period has elapsed. The predetermined time period may be measured by, for example, the timer43. The predetermined time period may be, for example, about several seconds to several tens of seconds from the processing timing with reference to any one of step ST44, step ST48, and step ST50. If the predetermined time period has not elapsed, the CPU41returns to step ST51. Accordingly, for example, after the doors are locked, the horn alarm is to be repeatedly output within the predetermined time period. An occupant, such as the driver11, exiting from the automobile1can recognize a possibility of the child being left behind unattended based on the repeatedly-output horn alarm. When the CPU41serves as a determiner to determine that the in-vehicle object is a child based on the detection level of a millimeter reflection wave detected by each of the millimeter-wave sensors31to39, the CPU41repeats the determination process based on the tendency of a temporal change with respect to the detection level of the millimeter reflection wave detected by each of the millimeter-wave sensors31to39. Then, in the repeated determination process, if the detection level of the millimeter reflection wave detected by each of the millimeter-wave sensors31to39with reference to a detection-level variation immediately after the boarding process temporally decreases to a predetermined amount or more as compared with the detection-level variation immediately after the boarding process in a state where the automobile1has stably stopped, and then becomes stable in the decreased state below the detection-level variation immediately after the boarding process, the determination of the in-vehicle object is changed from a child to baggage. Accordingly, for example, after determining that the in-vehicle object is a child at a time point T2inFIG.8, the CPU41can determine that the in-vehicle object is baggage at a time point T3. When the predetermined time period elapses, the CPU41proceeds to step ST55.

In step ST55, the CPU41outputs an alarm to the user terminal29. The CPU41transmits an alarm message indicating that the child is left behind unattended to the user terminal29via the wireless communication device24. The user terminal29reproduces the received alarm message. An occupant, such as the driver11, carrying the user terminal29and exiting from the automobile1can recognize a possibility of the child being left behind unattended based on the alarm output to the user terminal29that the occupant is carrying. If the child in the vehicle cabin3is detected when the occupant exits from the automobile1, the wireless communication device24serves as an alarm unit that outputs an alarm indicating that the child is left behind unattended to the occupant exiting from the automobile1. If the child in the vehicle cabin3is not detected when the occupant exits from the automobile1, the wireless communication device24does not output the alarm.

In step ST56, the CPU41determines whether the alarm is repeatedly output a predetermined number of times in step ST55. If the alarm is not repeatedly output the predetermined number of times in step ST55, the CPU41returns to step ST55. Accordingly, the CPU41repeatedly executes the output of the alarm in step ST55, so that the alarm indicating a possibility of the child being left behind unattended can be repeatedly output to the occupant, such as the driver11, carrying the user terminal29and exiting from the automobile1. When the alarm is repeatedly output the predetermined number of times in step ST55, the CPU41ends the control process.

Accordingly, if it is determined that the child is left behind in the vehicle cabin3when the occupant exits from the automobile1, the CPU41serves as an alarm unit that outputs an alarm indicating that the child is left behind unattended to the occupant exiting from the automobile1. If it is determined that the child is not left behind in the vehicle cabin3when the occupant exits from the automobile1, the CPU41serving as an alarm unit does not output the alarm. In addition, the CPU41can output alarms in an orderly sequence from a plurality of alarm output devices, including the user interface device25provided in the vehicle cabin3of the automobile1and the user terminal29carried by the occupant exiting from the automobile1, in accordance with the kinds of operations and the sequence of operations performed by the occupant exiting from the automobile1.

Accordingly, in this embodiment, each of the millimeter-wave sensors31to39outputs a millimeter radio wave toward the vehicle cabin3of the automobile1and detects a millimeter reflection wave from an in-vehicle object, such as either of an occupant and baggage, in the vehicle cabin3of the automobile1. By using a millimeter wave, the detection level of a reflection wave when there is an in-vehicle object, such as an occupant, in the vehicle cabin3can be varied from a case where there is no in-vehicle object, such as an occupant, in the vehicle cabin3. By using a millimeter wave, a child and baggage located behind a blocking object in the vehicle cabin3can be detected, so that at least the presence or absence of an in-vehicle object can be detected based on the detection level of a millimeter reflection wave. The CPU41determines the type of in-vehicle object in the vehicle cabin3of the automobile1based on the detection level of the millimeter reflection wave detected by each of the millimeter-wave sensors31to39. Accordingly, the CPU41can basically determine that an in-vehicle object possibly present in the vehicle cabin3of the automobile1is, for example, either of an adult and a child or either of a child and baggage.

However, the detection level of a millimeter reflection wave is not necessarily clearly divided for each type of in-vehicle object. In particular, the difference between the detection level of a millimeter reflection wave from a child and the detection level of a millimeter reflection wave from baggage basically tends to be small, and the magnitude relationship therebetween may be inverted in some cases. For example, the detection level of a millimeter reflection wave from transparent-liquid-containing baggage, such as a plastic bottle containing a liquid, may sometimes be higher than the detection level of a millimeter reflection wave from a child. Therefore, it is difficult to properly determine the type of in-vehicle object by comparing the fixed threshold value set in advance with the detection level of a millimeter reflection wave detected by each millimeter-wave sensor. Therefore, the plastic bottle containing the liquid may erroneously be determined to be a child, or the possibility of the child being erroneously determined to be baggage may increase if the threshold value is increased for preventing the erroneous determination.

Therefore, in this embodiment, instead of completing the in-vehicle-object type determination process by simply comparing the detection level of a millimeter reflection wave with the threshold value, a process for re-determining whether the in-vehicle object is either of a child and baggage is subsequently performed while the automobile1is traveling. In detail, the CPU41re-determines whether the in-vehicle object is either of a child and baggage based on the magnitude of a positional change of the in-vehicle object when the behavior of the automobile1greatly changes due to the movement of the automobile1detected by the movement sensor22. Accordingly, in this embodiment, even in a situation where the difference between the detection level of a millimeter reflection wave from a child and the detection level of a millimeter reflection wave from baggage is small and it is difficult to accurately determine the type of in-vehicle object by simply comparing the detection level of a millimeter reflection wave with the threshold value, it is expected that erroneous determination between a child and baggage with respect to such an in-vehicle object can be reduced.

Accordingly, in this embodiment, the accuracy with respect to the determination of the type of in-vehicle object based on the detection result of the vehicle cabin3obtained by using a millimeter radio wave can be enhanced.

In this embodiment, if a child is detected based on a determination result obtained when an occupant exits from the automobile1, an alarm indicating that the child is left behind unattended is output to the occupant exiting from the automobile1. Accordingly, in this embodiment, if the child is possibly left behind unattended in the automobile1from which the occupant is exiting, the in-vehicle object is determined to be a child as much as possible, so that the alarm indicating that the child is left behind unattended can be output to the occupant exiting from the automobile1.

In addition, in this embodiment, even if an in-vehicle object is determined to be a child as much as possible in this manner, when an in-vehicle object not determined to be a child is left behind, the alarm is not output to the occupant exiting from the automobile1. It is possible to prevent the alarm from being output excessively with respect to baggage serving as an in-vehicle object with a very low possibility of being a child.

Although the above embodiment of the disclosure has been described as an example, the embodiment of the disclosure is not limited to that described above, and various modifications and alterations are possible so long as they do not deviate from the embodiment of the disclosure.

For example, in the control system20serving as an unattended-occupant determination apparatus of the automobile1in the above embodiment, the CPU41of the in-vehicle-object determination device21executes all of the processes including the control of the millimeter-wave sensors31to39, the determination of the presence and absence of an in-vehicle object and the type thereof, and the determination of whether, for example, a child is left behind unattended.

Alternatively, for example, similar to the in-vehicle-object determination device21, the other devices22to25provided in the control system20may each have an input-output unit and a CPU that are coupled to the in-vehicle network26. The CPU of each of these devices22to25may partially or entirely execute the processes executed by the CPU41. A plurality of CPUs may operate in cooperation with each other to execute the above-described processes of the CPU41in a distributive manner.

In the above embodiment, in a case where the determiner detects a child in the vehicle cabin3when an occupant exits from the automobile1, the alarm unit outputs an alarm indicating that the child is left behind unattended to the occupant exiting from the automobile1. In a case where the determiner does not detect a child in the vehicle cabin3when the occupant exits from the automobile1, the alarm unit does not output the alarm to the occupant exiting from the automobile1.

Furthermore, in accordance with the kinds of operations and the sequence of operations performed by an occupant exiting from the automobile1and detected by the detector that detects the plurality of kinds of operations, including opening and closing of the doors of the automobile1, to be performed by the occupant when exiting from the automobile1, the alarm unit can output alarms in an orderly sequence from a plurality of alarm output devices, including the user interface device25provided in the vehicle cabin3of the automobile1and the user terminal29carried by the occupant exiting from the automobile1.

The control system20illustrated inFIG.3can be implemented by circuitry including at least one semiconductor integrated circuit such as at least one processor (e.g., a central processing unit (CPU)), at least one application specific integrated circuit (ASIC), and/or at least one field programmable gate array (FPGA). At least one processor can be configured, by reading instructions from at least one machine readable tangible medium, to perform all or a part of functions of the control system20including the in-vehicle-object determination device21, the movement sensor22, the door sensor23, the wireless communication device24, the user interface (UI) device25, and the in-vehicle network26. Such a medium may take many forms, including, but not limited to, any type of magnetic medium such as a hard disk, any type of optical medium such as a CD and a DVD, any type of semiconductor memory (i.e., semiconductor circuit) such as a volatile memory and a non-volatile memory. The volatile memory may include a DRAM and a SRAM, and the non-volatile memory may include a ROM and a NVRAM. The ASIC is an integrated circuit (IC) customized to perform, and the FPGA is an integrated circuit designed to be configured after manufacturing in order to perform, all or a part of the functions of the modules illustrated inFIG.3.