JP7659466B2 - Seat heater control device - Google Patents

Description

The present invention relates to a seat heater control device for controlling the supply of electricity to a seat heater provided in a vehicle seat.

The heated seat disclosed in Patent Document 1 includes a heating element, a temperature detection means for detecting the temperature of the heating element, a control means for controlling the flow of electricity to the heating element in accordance with the temperature detected by the temperature detection means, a seat temperature detection means located under the seat cover for detecting the temperature of the seat, and a seating determination means for determining whether or not a person is seated in the seat, and the seating determination means determines whether or not a person is seated based on the amount of change in temperature detected by the seat temperature detection means over a predetermined period of time.

JP 2008-285145 A

However, when determining whether or not a person is seated based on the amount of change in temperature of the seat surface, there is a possibility that an erroneous determination as to whether or not a person is seated may be made if, for example, an object with excellent heat retention properties is placed on the seat.
The present inventors have found that using a thermal camera to determine whether a person is seated is effective in preventing such erroneous determination.
However, since the size of the heated area of the seat heater in the thermal image of the thermo camera changes depending on the seat position, such as the reclining angle and the fore-aft position of the seat, it is necessary to determine whether a passenger is seated while taking into account differences in the seat position.
However, since the number of all possible seat position patterns is enormous, it is desirable to be able to perform seating determination with a simple configuration while dealing with differences in seat positions.

The present invention was made in consideration of the current situation, and its purpose is to provide a seat heater control device that can determine whether a person is seated based on thermal images from a thermo camera with a simple configuration while dealing with differences in seat position.

According to the present invention, in one aspect, a seat heater control device refers to a table that associates reference heat distribution information, which is information on the heat distribution in the seat when the seat heater is energized and no occupant is seated in the seat, with the seat position to obtain the reference heat distribution information corresponding to the actual seat position, compares the obtained reference heat distribution information with information on a thermal image including an area heated by the seat heater captured by a thermal camera, detects whether or not an occupant is seated in the seat, and controls energization of the seat heater depending on whether or not an occupant is seated, and determines the actual reference heat distribution information stored in the table. The system includes a first acquisition unit that obtains reference heat distribution information at an actual seat position from reference heat distribution information stored in correspondence with a seat position that is close to the seat position; a second acquisition unit that performs an interpolation process based on reference heat distribution information stored in the table in correspondence with a plurality of seat positions that are close to the actual seat position to obtain reference heat distribution information at the actual seat position; and a selection unit that selects either the first acquisition unit or the second acquisition unit according to a seating detection condition and obtains reference heat distribution information at the actual seat position using the selected acquisition unit.

The present invention makes it possible to determine whether a person is seated based on thermal images from a thermo camera with a simple configuration that can handle differences in seat position.

FIG. 2 is a block diagram of a seat heater system. FIG. 4 is a diagram showing the arrangement of a seat heater. FIG. 13 is a diagram showing a reference heat distribution table of a seat back portion. FIG. 13 is a diagram showing a reference heat distribution table of a seat cushion portion. FIG. 13 is a diagram showing reference heat distribution information. FIG. 2 is a functional block diagram of the seat heater control device. 13 is a diagram showing a state in which a thermal camera for photographing the first row seats is placed on the ceiling. FIG. 13 is a diagram showing a state in which a thermal camera for photographing the first row seats is disposed in a center console. 13 is a diagram showing a state in which a thermal camera for photographing the second row seats is placed on the ceiling. FIG. 13 is a diagram showing a state in which a thermal camera for photographing the second row seats is disposed in a center console. 4 is a flowchart showing a seating detection process performed by the seat heater control device. 10 is a flowchart showing a process of a first acquisition unit for obtaining reference heat distribution information of a seat cushion portion. 10 is a flowchart showing a process of a second acquisition unit for obtaining reference heat distribution information of a seat back portion. 10 is a flowchart showing a process of a second acquisition unit for obtaining reference heat distribution information of a seat cushion portion.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a seat heater control device according to the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing one embodiment of a seat heater system for a vehicle including a seat heater control device.
The seat heater system 100 is a system for heating a seat 20 of a vehicle, and basically includes a seat heater switch 200, a seat heater control device 300, a thermistor 400, and a seat heater 500.

The seat heater 500 is an electric resistance type heater unit, and is provided in the seat 20 in a pair consisting of a seat back heater 500A and a seat cushion heater 500B.
The seat heater switch 200 is a switch operated by a vehicle occupant. The occupant can arbitrarily select whether to activate or stop heating by the seat heater 500 by turning the seat heater switch 200 on and off.
The thermistor 400 is an element for detecting the surface temperature of the seat 20 equipped with the seat heater 500 .

The seat heater control device 300 is an electronic control device equipped with a microcomputer including a microprocessor, a memory, etc., and controls the supply of electricity to the seat heater 500 .
The seat heater control device 300 acquires an on/off signal from the seat heater switch 200 and a detection signal of the seat surface temperature detected by the thermistor 400 .
When the seat heater switch 200 is turned on, the seat heater control device 300 adjusts the amount of electricity supplied to the seat heater 500 so that the seat surface temperature detected by the thermistor 400 becomes the set temperature.
On the other hand, when the seat heater switch 200 is turned off, the seat heater control device 300 cuts off the power supply to the seat heater 500 .

The seat heater control device 300 also includes a seating detection unit as a functional unit that detects whether or not an occupant is seated in the seat 20 equipped with the seat heater 500 .
Furthermore, the seat heater control device 300 includes a heater control section as a functional section that controls the supply of electricity to the seat heater 500 depending on whether or not an occupant is seated in the seat 20 .
The heater control unit of the seat heater control device 300 automatically stops the supply of electricity to the seat heater 500 provided in the seat 20 when no occupant is seated in the seat 20 .
By providing the seat heater control device 300 with the heater control section, even if the occupant forgets to turn off the seat heater switch 200, the power supply to the seat heater 500 is stopped, and power consumption is suppressed.

The seat heater system 100 also includes a thermal camera 600 that is used by the seat heater control device 300 to detect whether or not an occupant is seated on the seat 20 .
The thermal camera 600 photographs the area heated by the seat heater 500, in other words the area including the seat cover on which the seat heater 500 is installed, from the front of the seat 20 equipped with the seat heater 500, and outputs a thermal image.

The seat heater control device 300 obtains the heat distribution of the area heated by the seat heater 500 based on a thermal image of the seat 20 captured by the thermal camera 600 while the seat heater 500 is energized.
The seat heater control device 300 then detects whether or not an occupant is seated in the seat 20 by determining whether the actual heat distribution obtained based on the thermal image from the thermal camera 600 corresponds to the heat distribution in an unseated state.

FIG. 2 is a diagram showing an example of the arrangement of the thermal camera 600 and the seat heater 500 in the vehicle 10. As shown in FIG.
The seat 20 has a seat back portion 20A (in other words, a backrest portion), a seat cushion portion 20B (in other words, a seat surface portion), and a headrest portion 20C.
A seat back heater 500A is provided in the seat back portion 20A, and a seat cushion heater 500B is provided in the seat cushion portion 20B.

When the driver's seat and the passenger's seat are seats 20 equipped with seat heaters 500, the thermal camera 600 is installed, for example, on the ceiling 11 near the rear-view mirror 40 inside the vehicle interior 30.
In this case, the viewing angle and camera direction of the thermal camera 600 are set so that it can capture a thermal image including the area heated by the seat heater 500 of the driver's seat 20 and the area heated by the seat heater 500 of the passenger's seat 20.
In other words, the thermal camera 600 is installed so as to be able to capture thermal images of the driver's seat and the passenger seat.

In addition, when the driver's seat and the passenger's seat are seats 20 equipped with seat heaters 500, seat heater switches 200 are generally provided separately for the driver's seat and the passenger's seat.
In this case, the seat heater control device 300 determines whether or not each seat 20 is occupied based on the thermal image from the thermal camera 600 for the driver's seat and/or passenger seat where the seat heater switch 200 is turned on, and decides whether to stop power supply or continue power supply for each seat 20.

The process of detecting whether a passenger is seated or not by the seat heater control device 300 will be described in more detail below.
The non-volatile memory built into the seat heater control device 300 pre-stores information regarding the thermal distribution of the thermal image expected to be obtained from the thermal camera 600 when power is applied to the seat heater 500 and no occupant is seated, in other words, information regarding the surface temperature of the seat 20 when power is applied to the seat heater 500 and no occupant is seated, as reference thermal distribution information (criteria data).

When an occupant sits on the seat 20, the seat surface which is the area heated by the seat heater 500 becomes invisible to the thermo camera 600 due to the seated occupant, and the thermo camera 600 photographs the occupant instead of the seat surface of the heated area.
Here, the surface temperature of the heated area of the seat 20 while the seat heater 500 is energized is generally about 40° C., which is higher than the surface temperature of a person (body temperature or the surface temperature of clothes).

Therefore, in the thermal image of the thermo camera 600, the temperature of the area heated by the seat heater 500 will drop when the occupant sits in the seat.
In other words, when an occupant sits in the seat 20, the heated area (skin temperature area of about 40°C) in the actual thermal image of the thermal camera 600 does not match the heated area in the thermal image of the thermal camera 600 when the occupant is not seated.

Therefore, the seat heater control device 300 stores in a non-volatile memory reference heat distribution information, which is information about the heat distribution in the heated area when the seat heater 500 is energized and no occupant is seated in the seat 20.
The seat heater control device 300 then compares the reference heat distribution information with the heat distribution information in the thermal image actually captured by the thermal camera 600, and detects whether or not an occupant is seated in the seat 20 by determining whether the two match or not.

Here, when the seat position of the seat 20 is changed, the relative positions of the thermocamera 600 and the heated area of the seat heater 500 change, and as a result, the heat distribution in the thermal image of the thermocamera 600 when power is applied to the seat heater 500 and no occupant is seated in the seat 20, in other words, the size of the heated area in the thermal image, changes.
Therefore, the seat heater control device 300 is equipped with a reference heat distribution information acquisition unit, which is a functional unit that stores a table in an internal non-volatile memory that corresponds to reference heat distribution information and seat position, and refers to the table to obtain the reference heat distribution information corresponding to the actual seat position at that time.
This allows the seat heater control device 300 to maintain the accuracy of seating detection based on the thermal image captured by the thermal camera 600 even if the seat position is changed.

The seat heater system 100 includes a seat position sensor that detects the seat position of the seat 20 so that the seat heater control device 300 sets the reference heat distribution information according to the seat position of the seat 20 .
The seat heater system 100 includes a seat front-rear position sensor 610, a seat angle position sensor 620, a seat height position sensor 630, and a seat cushion inclination sensor 640 as seat position sensors.

The seat front-rear position sensor 610 detects the front-rear sliding position of the seat 20 having a seat sliding function, in other words, the front-rear sliding distance [mm] of the entire seat 20 .
The seat angle position sensor 620 detects the reclining angle [deg] of the seat back portion 20A of the seat 20 that is equipped with a seat reclining function.
The seat height position sensor 630 detects the lift amount [mm] of the entire seat cushion portion 20B of the seat 20 equipped with a seat lifter function.
The seat cushion inclination sensor 640 detects the inclination angle [deg] of the seat cushion portion 20B of the seat 20 equipped with a seat cushion angle adjustment function (or the lift amount [mm] of the front end of the seat cushion portion 20B).

It should be noted that the seat 20 is not limited to a seat 20 that is equipped with all of an adjustment mechanism for the forward/backward sliding position of the entire seat 20, an adjustment mechanism for the reclining angle of the seat back portion 20A, an adjustment mechanism for the height of the entire seat cushion portion 20B, and an adjustment mechanism for the inclination of the seat cushion portion 20B.
When the seat 20 is provided with some kind of seat position adjustment mechanism, a sensor for detecting the seat position may be provided.

However, in a table that associates reference heat distribution information with seat positions (hereinafter referred to as the reference heat distribution table), if reference heat distribution information is registered for every pattern of seat positions, the memory capacity required to store the reference heat distribution table becomes large because there are a large number of seat position patterns.
Therefore, in the reference heat distribution table stored in the seat heater control device 300, reference heat distribution information is registered for patterns that are thinned out from all seat position patterns, thereby saving memory capacity for storing the reference heat distribution table.

For example, it is assumed that the variable range and adjustment step unit of the seat position of the seat 20 are as follows:
- Front-rear sliding position of entire seat 20: Adjustable in 1 mm increments within a variable range from 0 mm to 200 mm - Reclining angle of seat back portion 20A: Adjustable in 1 degree increments within a variable range from 90 degrees to 180 degrees - Height of seat cushion portion 20B: Adjustable in 1 mm increments within a variable range from 0 mm to 100 mm - Tilt of seat cushion portion 20B: Fixed

In this case, the position of the seat back portion 20A changes depending on the combination of the forward/rearward sliding position of the entire seat 20 and the reclining angle of the seat back portion 20A, so there are 201×91=18291 possible position patterns.
As for the seat cushion part 20B, the position changes depending on the combination of the front-rear sliding position of the entire seat 20 and the height of the seat cushion part 20B, so that there are 201×101=20301 possible position patterns.

In contrast, in the reference heat distribution table stored in the non-volatile memory of the seat heater control device 300, for example, the resolution of the reclining angle of the seat back portion 20A is set to 10 degrees, and the resolution of the height of the seat cushion portion 20B is set to 50 mm.
By thinning out the seat positions in this way, the number of patterns of the position of the seat back portion 20A in the reference heat distribution table is reduced from 18,291 patterns, which are all adjustable patterns, to 201×10=2010 patterns.
In addition, the number of patterns of the position of the seat cushion portion 20B in the reference heat distribution table is reduced from 20,301 patterns, which are all adjustable patterns, to 201×3=603 patterns.
Furthermore, if the number of position patterns is reduced, the capacity required to store the reference heat distribution table is reduced.

In the above example, the resolution of the reference heat distribution table for the front-to-back slide position of the entire sheet 20 is set to 1 mm, which is an adjustable unit. However, for example, by setting the resolution of the front-to-back slide position of the entire sheet 20 to 4 mm in setting the reference heat distribution table, it is possible to thin out the patterns of the front-to-back slide position.
FIG. 3 shows a reference heat distribution table for the seat back portion 20A when the resolution of the front-rear sliding position of the entire seat 20 is set to 4 mm, and the resolution of the reclining angle of the seat back portion 20A is set to 10 degrees.
FIG. 4 shows a reference heat distribution table for the seat cushion portion 20B when the resolution of the front-rear slide position of the entire seat 20 is set to 4 mm and the resolution of the height of the seat cushion portion 20B is set to 50 mm.

Furthermore, FIG. 5 shows data stored as information on the heat distribution of the heated area for each seat position in the reference heat distribution table for the seat back portion 20A and the reference heat distribution table for the seat cushion portion 20B.
In the reference heat distribution table for the seat back portion 20A, the horizontal dimension SBx and vertical dimension SBy of the heating area by the seat back heater 500A are stored for each combination of the front-rear sliding position of the entire seat 20 and the reclining angle of the seat back portion 20A.
On the other hand, in the reference heat distribution table for the seat cushion portion 20B, the horizontal dimension SKx and vertical dimension SKy of the heating area by the seat cushion heater 500B are stored for each combination of the front-to-rear slide position of the entire seat 20 and the height of the seat cushion portion 20B.

The seat heater control device 300 refers to the reference heat distribution table as shown in FIG. 3 and FIG. 4 to search for information on the heat distribution of the heating area corresponding to the seat position at that time, specifically, information on each of the dimensions SBx, SBy, SKx, and SKy.
The seat heater control device 300 then detects whether an occupant is seated in the seat 20 based on whether a heated area with a horizontal dimension SBx and a vertical dimension SBy is detected in the thermal image of the thermal camera 600 for the seat back portion 20A, and whether a heated area with a horizontal dimension SKx and a vertical dimension SKy is detected for the seat cushion portion 20B.

Here, by thinning out the seat position patterns in the reference heat distribution table, the capacity of the reference heat distribution table is reduced, but there may be cases where the actual seat position does not correspond to any of the seat positions in the reference heat distribution table.
For example, when the front-rear slide position of the entire seat 20 is 0 mm and the height of the seat cushion portion 20B is 10 mm, there is no corresponding seat position in the reference heat distribution table of the seat cushion portion 20B in FIG.

Therefore, the seat heater control device 300 is provided with two functional units as functional units for acquiring reference heat distribution information corresponding to the actual seat position when the actual seat position does not correspond to any of the seat positions in the reference heat distribution table, and is configured to selectively use these two functional units.
The seat heater control device 300 has a first acquisition unit, which is a functional unit that obtains reference heat distribution information at the actual seat position from the reference heat distribution information stored in the reference heat distribution table, the reference heat distribution information being stored corresponding to a seat position that approximates the actual seat position.

In addition, the seat heater control device 300 is equipped with a second acquisition unit, which is a functional unit that performs interpolation processing based on reference heat distribution information stored in the reference heat distribution table corresponding to multiple seat positions that approximate the actual seat position, to obtain reference heat distribution information at the actual seat position.
Furthermore, the seat heater control device 300 is equipped with a selection unit which is a functional unit that selects either the first acquisition unit or the second acquisition unit depending on the conditions for seating detection, and acquires reference heat distribution information at the actual seat position using the selected acquisition unit.

Hereinafter, one aspect of the process of acquiring reference heat distribution information by the first acquisition unit will be described based on a specific example.
Here, when using the reference heat distribution table of the seat cushion portion 20B shown in FIG. 4, it is assumed that the actual seat position is such that the forward/rearward sliding amount of the entire seat 20 is 0 mm and the height of the seat cushion portion 20B is 10 mm.
Under these conditions, since there is a column in the reference heat distribution table with a front-back sliding amount of 0 mm that matches the actual front-back sliding amount, the first selection unit selects the column with the front-back sliding amount of 0 mm as the search target.

On the other hand, in the reference heat distribution table of FIG. 4, the resolution of the height of the seat cushion portion 20B is set to 50 mm, and the height of the seat cushion portion 20B is limited to any one of 0 mm, 50 mm, and 100 mm.
That is, in the reference heat distribution table of FIG. 4, no reference heat distribution information corresponding to 10 mm which is the actual height of the seat cushion portion 20B is stored.
Here, the first selection unit selects the 0 mm row which is closest to the actual height of the seat cushion portion 20B, 10 mm, from the 0 mm row, 50 mm row, and 100 mm row in the reference heat distribution table of Figure 4.

In other words, when the front-to-rear sliding amount of the entire seat 20 is 0 mm and the height of the seat cushion portion 20B is 10 mm, the first selection unit selects, from the combinations of front-to-rear sliding amount and height in the reference heat distribution table of Figure 4, the combination when the front-to-rear sliding amount is 0 mm and the height of the seat cushion portion 20B is 0 mm as the seat position that is closest to the actual seat position.
Then, the first selection unit obtains the reference heat distribution information (SKx1, SKy1) stored corresponding to the front-rear slide amount being 0 mm and the height of the seat cushion portion 20B being 0 mm as the reference heat distribution information at the actual seat position.

Next, one aspect of the process of acquiring reference heat distribution information by the second acquisition unit will be described based on a specific example.
Here, when using the reference heat distribution table for the seat back portion 20A shown in FIG. 3, it is assumed that the actual seat position is such that the forward/rearward sliding amount of the entire seat 20 is 0 mm and the reclining angle of the seat back portion 20A is 94 degrees.
Under this condition, since there is a column in the reference heat distribution table with a front-to-back sliding amount of 0 mm that matches the actual front-to-back sliding amount, the second acquisition unit selects the column with the front-to-back sliding amount of 0 mm as the search target.

On the other hand, in the reference heat distribution table of FIG. 3, the resolution of the reclining angle of the seat back portion 20A is set to 10 degrees, and the reclining angle next to 90 degrees is 100 degrees.
That is, in the reference heat distribution table of FIG. 3, no reference heat distribution information corresponding to 94 degrees, which is the actual reclining angle of the seat back portion 20A, is stored.

Here, the second acquisition unit selects, from the reclining angle rows in the reference heat distribution table of Figure 3 (the row for 90 degrees, the row for 100 degrees, the row for 110 degrees, etc.), the row for 90 degrees which is the closest in the direction where the angle is smaller than 94 degrees, and the row for 100 degrees which is the closest in the direction where the angle is larger than 94 degrees.
In other words, the second acquisition unit selects, from among the columns in which the forward/backward sliding amount is 0 mm, the two rows with angles that sandwich the actual reclining angle (94 deg) as a plurality of seat positions that approximate the actual seat position.

Then, the second acquisition unit reads out the reference heat distribution information (SBx1, SBy1) stored corresponding to the front-to-back sliding amount = 0 mm and the reclining angle = 90 degrees, and further reads out the reference heat distribution information (SBx2, SBy2) stored corresponding to the front-to-back sliding amount = 0 mm and the reclining angle = 100 degrees.
Next, the second acquisition unit obtains reference heat distribution information (SBx, SBy) at an actual reclining angle of 94 degrees by interpolation processing based on the reference heat distribution information (SBx1, SBy1) at a reclining angle of 90 degrees and the reference heat distribution information (SBx2, SBy2) at a reclining angle of 100 degrees.

The second acquisition unit calculates the vertical dimension SBy when the actual reclining angle is 94 degrees according to the following formula.
SBy=SBy1-ΔBy
ΔBy={(SBy1-SBy2)/10}*(94-90)
Similarly, the second acquisition unit calculates the horizontal dimension SBx when the actual reclining angle is 94 deg according to the following formula.
SBx=SBx1-ΔBx
ΔBx={(SBx1-SBx2)/10}*(94-90)

The "10" in the above formula is 10 degrees, which is the resolution of the reclining angle in the reference heat distribution table, and (SBy1-SBy2)/10 and (SBx1-SBx2)/10 indicate the amount of dimensional change per unit reclining angle.
In the above formula, "94" indicates the actual reclining angle, and "90" indicates 90 degrees, which is the reclining angle that is closest to the actual reclining angle of 94 degrees in the direction of smaller angles in the reference heat distribution table.

For example, when SBy1=400 mm and SBy2=360 mm, the vertical dimension SBy at the actual seat position is obtained from the above formula as follows:
ΔBy={(400-360)/10}*(94-90)=16
SBy=400-16=384
Similarly, when SBx1=300 mm and SBx2=300 mm, the vertical dimension SBx at the actual seat position is obtained from the above formula as follows:
ΔBx={(300-300)/10}*(94-90)=0
SBx=300-0=300

Note that the above is an example of a case where a column of forward and backward sliding amounts that matches the actual forward and backward sliding amounts exists in the reference heat distribution table, but the second acquisition unit can acquire reference heat distribution information by interpolation processing even if a column of forward and backward sliding amounts that matches the actual forward and backward sliding amounts does not exist.
For example, in the reference heat distribution table of FIG. 3, the resolution of the forward/backward sliding amount is relatively fine, so the second selection unit can select the column of the forward/backward sliding amount that is closest to the actual forward/backward sliding amount, and then perform interpolation processing according to the deviation in the reclining angle as described above.
The second selection unit can also perform both the interpolation process according to the deviation in the forward/backward sliding amount and the interpolation process according to the deviation in the reclining angle.
Moreover, the second acquisition unit, in the same manner as in the case of the seat back portion 20A, refers to the reference heat distribution table of the seat cushion portion 20B and obtains reference heat distribution information that matches the actual seat position by an interpolation process.

FIG. 6 is a functional block diagram of the seat heater control device 300.
The seat heater control device 300 includes a reference heat distribution information acquisition unit 310 , a seating detection unit 320 , and a heater control unit 330 .
The reference heat distribution information acquisition unit 310 acquires information related to the seat position, and outputs reference heat distribution information.

The seating detection unit 320 acquires reference heat distribution information from the reference heat distribution information acquisition unit 310 and also acquires thermal image information from the thermal camera 600 , and outputs information regarding the presence or absence of an occupant seated on the seat 20 .
The heater control unit 330 acquires information regarding the presence or absence of an occupant from the seating detection unit 320 and controls the supply of electricity to the seat heater 500 .

Here, the reference heat distribution information acquisition unit 310 includes a first acquisition unit 311 , a second acquisition unit 312 , and a selection unit 313 .
The first acquisition unit 311 and the second acquisition unit 312 are functional units that refer to the reference heat distribution table to obtain reference heat distribution information corresponding to the actual seat position.
The selection unit 313 activates either the first acquisition unit 311 or the second acquisition unit 312 depending on the conditions for seating detection, and outputs reference heat distribution information corresponding to the actual seat position from the activated acquisition unit.

The process of selecting either the first acquisition unit 311 or the second acquisition unit 312, which is performed by the selection unit 313, will be described in detail below.
The first acquisition unit 311 performs a process of searching for reference heat distribution information stored in a reference heat distribution table corresponding to a seat position that is close to the actual seat position, and does not perform an interpolation process.
In response to this, the second acquisition unit 312 searches for reference heat distribution information stored in a reference heat distribution table corresponding to multiple seat positions that are close to the actual seat position, and performs interpolation processing based on this, thereby acquiring reference heat distribution information that is closer to the values at the actual seat position than the reference heat distribution information obtained by the first acquisition unit 311.

Therefore, the calculation load for obtaining the reference heat distribution information in the first acquisition unit 311 is smaller than that in the second acquisition unit 312 which performs the interpolation process.
However, when the reference heat distribution information is acquired by the first acquisition unit 311, the reference heat distribution information corresponding to a seat position that is shifted from the actual seat position is used for seating detection, so if there is a large difference in the reference heat distribution information due to differences in seat positions, the accuracy of seating detection will be lower than when the second acquisition unit 312 is used.

Therefore, the selection unit 313 selects either the first acquisition unit 311 or the second acquisition unit 312 depending on the conditions for seating detection so as to ensure the accuracy of seating detection while minimizing the computational load when obtaining reference heat distribution information, and acquires reference heat distribution information at the actual seat position using the selected acquisition unit.
In other words, the selection unit 313 selects the first acquisition unit 311 when the condition for seating detection is a condition that allows the first acquisition unit 311 to acquire reference heat distribution information that ensures the accuracy of seating detection.
On the other hand, when the conditions for seating detection are such that the first acquisition unit 311 cannot acquire reference heat distribution information that can ensure the accuracy of seating detection, the selection unit 313 selects the second acquisition unit 312 .

Here, if the positional relationship between the thermo camera 600 and the seat 20 (seat heater 500) is such that there is a large change in the heated area in the thermal image of the thermo camera 600 due to fluctuations in the seat position, the error in the reference heat distribution information acquired by the first acquisition unit 311 will be large, reducing the accuracy of seating detection.
Therefore, the selection unit 313 selects either the first acquisition unit 311 or the second acquisition unit 312 depending on the positional relationship between the thermal camera 600 and the sheet 20.

In other words, the selection unit 313 selects the first acquisition unit 311 when the positional relationship between the thermo camera 600 and the seat 20 is such that the change in the heated area in the thermal image due to a change in the seat position is smaller than a threshold value.
On the other hand, when the positional relationship between the thermo camera 600 and the seat 20 is such that the change in the heated area in the thermal image due to a change in the seat position is greater than the threshold value, the selection unit 313 selects the second acquisition unit 312 .

Furthermore, the change in the heated area in the thermal image caused by the change in the seat position differs between the seat back portion 20A and the seat cushion portion 20B.
Therefore, the selection unit 313 individually selects an acquisition unit that acquires reference heat distribution information of the seat back portion 20A and an acquisition unit that acquires reference heat distribution information of the seat cushion portion 20B.
Then, depending on the positional relationship between the thermal camera 600 and the seat 20, the selection unit 313 selects the first acquisition unit 311 for the seat cushion portion 20B, selects the second acquisition unit 312 for the seat back portion 20A, or selects the second acquisition unit 312 for both the seat back portion 20A and the seat cushion portion 20B.

In the following, a specific description will be given of the correlation between the positional relationship between the thermo camera 600 and the seat 20 and the acquisition unit selected by the selection unit 313 for each of the seat back unit 20A and the seat cushion unit 20B.
FIG. 7 shows a case where a thermal camera 600 for capturing thermal images of the driver's seat and passenger seat (in other words, the left and right seats in the first row, which is the front row) 20 is installed near the center of the vehicle width on the ceiling 11.
In the case of such a positional relationship between the thermo camera 600 and the seat 20, the selection unit 313 selects the second acquisition unit 312 for both the seat back portion 20A (seat back heater 500A) and the seat cushion portion 20B (seat cushion heater 500B).

FIG. 8 also shows a case where a thermo camera 600 for capturing thermal images of the driver's seat and passenger's seat 20 is installed on the dashboard 12 (or the center cluster 13 ), which is lower than the ceiling 11 .
In the case of such a positional relationship between the thermal camera 600 and the seat 20, the selection unit 313 selects the first acquisition unit 311 for the seat cushion portion 20B (seat cushion heater 500B) and selects the second acquisition unit 312 for the seat back portion 20A (seat back heater 500A).

When the thermo camera 600 is installed on the dashboard 12 (or the center cluster 13), the area heated by the seat cushion heater 500B in the thermal image of the thermo camera 600 varies little with changes in the height or front-rear position of the seat cushion portion 20B.
Therefore, even if the reference heat distribution information acquisition unit 310 acquires reference heat distribution information for the seat cushion portion 20B using the first acquisition unit 311, the reference heat distribution information can be acquired with sufficient accuracy in response to changes in the height and fore-aft position of the seat cushion portion 20B.
The seat heater control device 300 acquires the reference heat distribution information for the seat cushion portion 20B using the first acquisition unit 311, thereby reducing the calculation load in the process of acquiring the reference heat distribution information.

On the other hand, when the thermo camera 600 is installed on the dashboard 12 (or the center cluster 13), the area heated by the seat back heater 500A in the thermal image of the thermo camera 600 changes significantly depending on the reclining angle of the seat back portion 20A.
Therefore, when the reference heat distribution information acquisition unit 310 acquires the reference heat distribution information for the seat back portion 20A using the first acquisition unit 311, the accuracy of the reference heat distribution information decreases depending on the reclining angle of the seat back portion 20A.
Therefore, the selection unit 313 selects the second acquisition unit 312 for the seat back portion 20A, thereby making it possible to acquire the reference heat distribution information with high accuracy even if there is a change in the reclining angle of the seat back portion 20A.

On the other hand, when the thermo camera 600 is installed on the ceiling 11, the distance from the thermo camera 600 to the seat back portion 20A and the seat cushion portion 20B is long, and the change in the heated area in the thermal image becomes large due to the fluctuation in the height of the seat cushion portion 20B and the fluctuation in the reclining angle of the seat back portion 20A.
Therefore, when the thermo camera 600 is installed on the ceiling 11, the selection unit 313 selects the second acquisition unit 312 for the seat back portion 20A and the seat cushion portion 20B, thereby enabling the reference heat distribution information to be acquired with high accuracy even if there is a change in the height of the seat cushion portion 20B or a change in the reclining angle of the seat back portion 20A.

In this manner, the selection unit 313 selects either the first acquisition unit 311 or the second acquisition unit 312 for each of the seat back portion 20A and the seat cushion portion 20B depending on the installation position of the thermal camera 600, specifically, the installation height.
In other words, when the installation height of the thermal camera 600 is lower than a predetermined height, for example, when the thermal camera 600 is installed on the dashboard 12 (or the center cluster 13) as shown in FIG. 8, the selection unit 313 selects the first acquisition unit 311 for the seat cushion heater 500B and the second acquisition unit 312 for the seat back heater 500A.
On the other hand, when the installation height of the thermal camera 600 is higher than the specified height, for example, when the thermal camera 600 is installed on the ceiling 11 as shown in Figure 7, the selection unit 313 selects the second acquisition unit 312 for the seat cushion heater 500B and the seat back heater 500A.

The above describes the correlation between the installation position (installation height) of the thermal camera 600 that captures thermal images of the driver's seat and passenger's seat 20 and the selection process of the acquisition unit by the selection unit 313. However, the selection unit 313 also selects an acquisition unit for seats 20 in the second row and beyond of the vehicle 10 based on the same control characteristics as for the driver's seat and passenger's seat 20.
FIG. 9 shows a case in which the left and right seats 20-2 in the second row are equipped with seat heaters 500, and a thermo camera 600-2 for photographing the second row seats 20-2 is installed on the ceiling 11.

In the case of such a positional relationship between the seat 20-2 and the thermo camera 600-2, the installation height of the thermo camera 600-2 is higher than a predetermined height, and the change in the heated area in the thermal image will be large due to fluctuations in the height of the seat cushion portion 20B and fluctuations in the reclining angle of the seat back portion 20A.
Therefore, the selection unit 313 selects acquisition of reference heat distribution information by the second acquisition unit 312 for the seat back portion 20A and the seat cushion portion 20B of the second row seat 20-2.

Figure 10 shows a case where a thermal camera 600-2 capturing an image of the second row seat 20-2 is installed in the center console 13 located between the left and right seats 20 in the front row (the driver's seat and passenger seat 20 in the first row), i.e., the installation height of the thermal camera 600-2 is lower than a predetermined height.
In this case, the positional relationship between the seat 20-2 and the thermal camera 600-2 is the same as when the thermal camera 600 capturing images of the driver's seat and passenger seat 20 is installed on the dashboard 12 (or the center cluster 13).
Therefore, for the seat back portion 20A of the second row seat 20-2, the selection unit 313 selects the acquisition of reference heat distribution information by the second acquisition unit 312, and for the seat cushion portion 20B of the second row seat 20-2, the selection unit 313 selects the acquisition of reference heat distribution information by the first acquisition unit 311.

When the vehicle 10 is equipped with left and right seats 20 in the third row, the selection unit 313 selects either the first acquisition unit 311 or the second acquisition unit 312 for each of the seat back portion 20A and the seat cushion portion 20B depending on whether the thermal camera 600 that captures the images of the third row seats 20 is installed on the ceiling or the center console, in other words, whether the installation height of the thermal camera 600 is higher or lower than a predetermined height.

FIG. 11 is a flowchart showing an example of a seating detection process performed by the seat heater control device 300.
First, in step S801, the seat heater control device 300 selects the seat 20 to be subjected to the seating detection process.
If the vehicle 10 is, for example, a six-seater with three rows of seats, all of the seats 20 equipped with seat heaters 500, and each seat is equipped with a thermal camera 600, the seat heater control device 300 will perform the seating detection process in the following order, for example: passenger seat (left seat in the first example), driver's seat (right seat in the first example), left seat in the second row, right seat in the second row, left seat in the third row, and right seat in the third row.
Then, if there is a seat 20 among the six seats for which power is not applied to the seat heater 500, the seat heater control device 300 does not perform the seat occupancy detection process for that seat 20, but performs the seat occupancy detection process for the next seat 20 if power is applied to the seat heater 500.

When the seat heater control device 300 selects the seat 20 to be subjected to the seating detection process in step S801, the process proceeds to step S802.
In step S802, the seat heater control device 300 acquires the output signals of the seat front/rear position sensor 630, the seat angle position sensor 640, the seat height position sensor 650, and the seat cushion inclination sensor 660 provided on the seat 20 that is the subject of the seating detection process, and detects the seat position of the seat 20.

Next, the seat heater control device 300 proceeds to step S803, and acquires reference thermal distribution information, which is information about the thermal distribution of a thermal image in a non-seated state when power is applied to the seat heater 500 in the current seat position, based on the information about the seat position acquired in step S802.
As described above, the seat heater control device 300 refers to the reference heat distribution table in which the reference heat distribution information is associated with the seat position, and obtains the reference heat distribution information at the current seat position.

Furthermore, when the seat heater control device 300 refers to the reference heat distribution table to obtain reference heat distribution information at the current seat position, as described above, it selectively uses a method that can reduce the calculation load (first acquisition unit 311) and a method that has a relatively high calculation load but can obtain reference heat distribution information at the current seat position with high accuracy (second acquisition unit 312) based on the positional relationship between the thermal camera 600 and the seat 20.
For example, when a thermal camera 600 for photographing the driver's seat and passenger seat is installed on the dashboard 12 (or center cluster 13) (see Figure 8), the seat heater control device 300 selects a method (first acquisition unit 311) that can reduce the calculation load to obtain reference heat distribution information for the seat cushion portion 20B, and selects a method (second acquisition unit 312) for obtaining reference heat distribution information at the current seat position with high accuracy for the seat back portion 20A.

In the next step S804, the seat heater control device 300 compares the reference heat distribution information obtained in step S803 with the heat distribution of the heated area obtained from the thermal image captured by the thermal camera 600, and determines whether the heat distribution states match.
Here, the state in which the heat distribution of the heated area in the thermal image captured by the thermo camera 600 matches the reference heat distribution information is the state in which the thermal image captured by the thermo camera 600 corresponds to the heat distribution in a non-seated state, that is, the state in which the seat cover of the heated area is directly visible to the thermo camera 600.

Therefore, if the heat distribution of the heated area in the thermal image captured by the thermal camera 600 matches the reference heat distribution information, the seat heater control device 300 determines that no occupant is seated in the seat 20, and proceeds to step S805.
In step S805, the seat heater control device 300 automatically stops the supply of electricity to the seat heater 500 (the seat back heater 500A and the seat cushion heater 500B) of the seat 20.

This automatic stop control prevents the seat heater 500 of an unoccupied seat 20 from continuing to be energized, thereby preventing unnecessary consumption of electricity.
In addition, when the seat heater control device 300 detects that no one is seated in the seat 20, it can reduce the amount of electricity supplied to the seat heater 500, or reduce the amount of electricity or stop the supply of electricity after the duration of the no-occupancy determination reaches a predetermined time.

On the other hand, if the heat distribution of the heated area in the thermal image captured by the thermal camera 600 does not match the reference heat distribution information, that is, if it is estimated that the seat cover of the heated area is not directly visible from the thermal camera 600, the seat heater control device 300 proceeds to step S806 and performs a second seating detection process.
In other words, a state in which the thermal distribution of the heated area in the thermal image captured by the thermal camera 600 does not match the reference thermal distribution information is a state in which an object is present between the thermal camera 600 and the seat cover of the heated area, which may include a state in which an occupant is seated in the seat 20, or a state in which luggage is placed on the seat 20.
Therefore, if the thermal distribution of the heated area in the thermal image captured by the thermal camera 600 does not match the reference thermal distribution information, the seat heater control device 300 proceeds to step S806 and performs a second seating detection process to determine whether an occupant is seated in the seat 20 or luggage is placed on the seat 20.

In the second seating detection process of step S806, the seat heater control device 300 determines whether an occupant is seated in the seat 20 or luggage is placed on the seat 20, for example, based on the proportion of the seat 20 that is occupied by the person's surface temperature area.
In detail, the seat heater control device 300 determines whether an occupant is seated in the seat 20 or whether luggage is placed on the seat 20 by determining whether the proportion of the area in the headrest portion 20C of the seat 20 that indicates the temperature range of a person's body temperature (e.g., 36°C-37°C) is above a certain level.

In addition, the seat heater control device 300 determines whether an occupant is seated in the seat 20 or whether luggage is placed on the seat 20 by determining whether the temperature range including the surface temperature of clothing and body temperature, i.e., the proportion of the human surface temperature range, is above a certain level in the area of the seat back portion 20A or the seat cushion portion 20B.
When the seat heater control device 300 determines that a baggage is placed on the seat 20, it automatically stops the supply of electricity to the seat heater 500 (seat back heater 500A and seat cushion heater 500B) of the seat 20.

After completing the process in step S805 or S806, the seat heater control device 300 proceeds to step S807 to determine whether the seat occupancy/non-occupancy determination has been performed for all the seats 20 for which the seat heater 500 is energized.
Then, if the seat heater control device 300 has performed the occupancy/non-occupancy determination for all seats 20 for which power is applied to the seat heater 500, it ends this routine as is, but if there are any seats 20 remaining for which the occupancy/non-occupancy determination should be performed, it proceeds to step S808 to select the next seat 20 to be subjected to the occupancy/non-occupancy determination, and then returns to step S802.

FIG. 12 is a flowchart showing a process in which the first acquisition unit 311 acquires the reference heat distribution information of the seat cushion unit 20B.
For example, when a thermal camera 600 for photographing the driver's seat and passenger seat is installed on the dashboard 12 (or the center cluster 13) (see FIG. 8), the reference heat distribution information of the seat cushion portion 20B is obtained according to the flowchart of FIG.

First, in step S821, the first acquisition unit 311 acquires information on the forward/backward sliding amount of the entire seat 20 detected by the seat front/rear position sensor 610.
In addition, the first acquisition unit 311 acquires information on the height of the seat cushion portion 20B detected by the seat height position sensor 630 in the next step S822.

Next, in step S823, the first acquisition unit 311 determines whether or not reference heat distribution information corresponding to the combination of the acquired forward/rearward slide amount and the height of the seat cushion portion 20B is stored in the reference heat distribution table (see Figure 4).
For example, when using the reference heat distribution table of Figure 4, if the forward/backward slide amount is 0 mm and the height of the seat cushion portion 20B is 50 mm, the first acquisition unit 311 determines that the reference heat distribution information (SKx2, SKy2) corresponding to the actual seat position is stored.

If the reference heat distribution information corresponding to the combination of the front-rear sliding amount and the height of the seat cushion portion 20B is stored in the reference heat distribution table, the first acquisition unit 311 proceeds to step S824.
Then, in step S824, the first acquisition unit 311 reads out the reference heat distribution information stored in the reference heat distribution table corresponding to the combination of the forward/backward slide amount and the height of the seat cushion portion 20B (in other words, the actual seat position), and sets it as the reference heat distribution information to be used for seating detection of the seat cushion portion 20B.

On the other hand, if the reference heat distribution information corresponding to the actual seat position is not stored in the reference heat distribution table, for example, when the forward/backward slide amount is 0 mm and the height of the seat cushion portion 20B is 10 mm, the first acquisition unit 311 proceeds to step S825.
In step S825, the first obtaining unit 311 selects, in the reference heat distribution table, a column of a forward/backward sliding amount that matches or is most similar to the actual forward/backward sliding amount.

Next, the first acquisition unit 311 proceeds to step S826, reads out the reference heat distribution information stored corresponding to the height that matches or is closest to the actual height of the seat cushion portion 20B among the examples selected in step S825, and sets it as the reference heat distribution information to be used for seating detection of the seat cushion portion 20B.
For example, when the front-to-rear sliding amount is 0 mm and the height of the seat cushion portion 20B is 10 mm, the first acquisition unit 311 sets the reference heat distribution information (SKx1, SKy1) in the column in the reference heat distribution table of Figure 4 where the front-to-rear sliding amount is 0 mm and the height of the seat cushion portion 20B is 0 mm as the reference heat distribution information to be used for seating detection.

FIG. 13 is a flowchart showing a process in which the second acquisition unit 312 acquires the reference heat distribution information of the seat back portion 20A.
The second acquisition unit 312 first acquires information on the actual forward/backward sliding amount in step S831, and acquires information on the actual reclining angle in the next step S832.

Next, the second acquisition unit 312 proceeds to step S833 and determines whether or not reference heat distribution information corresponding to the combination of the acquired forward/backward sliding amount and reclining angle (actual seat position) is stored in the reference heat distribution table (see Figure 3).
Then, if reference heat distribution information corresponding to the combination of the actual forward/backward sliding amount and the actual reclining angle has been stored, the second acquisition unit 312 proceeds to step S834, reads out the reference heat distribution information stored in the reference heat distribution table corresponding to the combination of the actual forward/backward sliding amount and the actual reclining angle, and sets it as the reference heat distribution information to be used for seating detection of the seat back portion 20A.

On the other hand, if the reference heat distribution information corresponding to the combination of the actual forward/backward sliding amount and the actual reclining angle is not stored in the reference heat distribution table, the second acquisition unit 312 proceeds to step S835.
In step S835, the second obtaining unit 312 selects a column of the forward/backward sliding amount that matches or is most similar to the actual forward/backward sliding amount in the reference heat distribution table (see FIG. 3).

Next, in step S836, the second acquisition unit 312 determines two reclining angles from the reclining angles in the reference heat distribution table that are closest to the actual reclining angle, i.e., the first reclining angle that is closest on the side smaller than the actual reclining angle, and the second reclining angle that is closest on the side larger than the actual reclining angle.
Then, the second acquisition unit 312 obtains reference heat distribution information at the actual reclining angle by interpolation processing based on the reference heat distribution information at the first reclining angle and the reference heat distribution information at the second reclining angle.

For example, if the reference heat distribution information at a first reclining angle is (SBx1, SBy1) and the reference heat distribution information at a second reclining angle is (SBx2, SBy2), the second acquisition unit 312 calculates the vertical dimension SBy of the reference heat distribution information at the actual seat position according to the following formula.
In the formula below, RAa indicates the actual reclining angle, RA1 indicates the first reclining angle, and 10 indicates 10 degrees, which is the reclining angle step in the reference heat distribution table.

ΔBy={(SBy1-SBy2)/10}*(RAa-RA1)
SBy=SBy1-ΔBy
Similarly, the second acquisition unit 312 calculates the horizontal dimension SBx of the reference heat distribution information at the actual seat position according to the following formula.
ΔBx={(SBx1-SBx2)/10}*(RAa-RA1)
SBx=SBx1-ΔBx

FIG. 14 is a flowchart showing a process in which the second acquisition unit 312 acquires the reference heat distribution information of the seat cushion unit 20B.
The second acquisition unit 312 first acquires information on the actual forward/rearward sliding amount in step S841, and then acquires information on the actual height of the seat cushion portion 20B in the next step S842.

Next, the second acquisition unit 312 proceeds to step S843 and determines whether or not reference heat distribution information corresponding to the acquired combination of forward/backward slide amount and height (actual seat position) is stored in the reference heat distribution table (see Figure 4).
Then, if the reference heat distribution information corresponding to the combination of the actual forward/backward sliding amount and the actual height is stored in the reference heat distribution table, the second acquisition unit 312 proceeds to step S844, reads out the reference heat distribution information stored in the reference heat distribution table corresponding to the combination of the actual forward/backward sliding amount and the actual height, and sets it as the reference heat distribution information to be used for seating detection of the seat cushion portion 20B.

On the other hand, if the reference heat distribution information corresponding to the combination of the actual forward/backward sliding amount and the actual height is not stored, the second acquisition unit 312 proceeds to step S845.
In step S845, the second obtaining unit 312 selects a column of the forward/backward sliding amount in the reference heat distribution table (see FIG. 4) that matches or is most similar to the actual forward/backward sliding amount.
Next, in step S846, the second acquisition unit 312 determines two heights from the heights in the reference heat distribution table that are closest to the actual height, i.e., the first height that is closest on the side smaller than the actual height, and the second height that is closest on the side larger than the actual height.
Then, the second acquisition unit 312 obtains reference heat distribution information at the actual height by an interpolation process based on the reference heat distribution information at the first height and the reference heat distribution information at the second height.

For example, if the reference heat distribution information at the first height is (SKx1, SKy1) and the reference heat distribution information at the second height is (SKx2, SKy2), the second acquisition unit 312 calculates the vertical dimension SKy of the reference heat distribution information at the actual seat position according to the following formula.
In the formula below, CHa indicates the actual height, CH1 indicates the first height, and 50 indicates 50 mm, which is the height step of the reference heat distribution table.

ΔKy={(SKy1-SKy2)/50}*(CHa-CH1)
SKy=SKy1-ΔKy
Similarly, the second acquisition unit 312 calculates the horizontal dimension SKx of the reference heat distribution information at the actual seat position according to the following formula.
ΔKx={(SKx1-SKx2)/50}*(CHa-CH1)
SKx=SKx1-ΔKx

The technical ideas described in the above embodiments can be used in any suitable combination as long as no contradiction occurs.
Furthermore, although the contents of the present invention have been specifically described with reference to preferred embodiments, it is obvious that a person skilled in the art can adopt various modified embodiments based on the basic technical concept and teachings of the present invention.

For example, when the seat heater control device 300 determines that the actual heat distribution does not match the reference heat distribution information during seating detection based on the reference heat distribution information acquired by the first acquisition unit 311, it can acquire the reference heat distribution information again by the second acquisition unit 312 and reconfirm whether the actual heat distribution matches the reference heat distribution information.
Furthermore, for example, when obtaining reference heat distribution information of the seat back portion 20A, the seat heater control device 300 can selectively use the first acquisition unit 311 and the second acquisition unit 312 depending on the magnitude of the reclining angle.
In other words, the seat heater control device 300 can acquire reference heat distribution information by the first acquisition unit 311 in reclining angle regions where the change in the reference heat distribution information in response to a change in the reclining angle is relatively small, and can acquire reference heat distribution information by the second acquisition unit 312 in reclining angle regions where the change in the reference heat distribution information in response to a change in the reclining angle is relatively large.

In addition, when the seat heater control device 300 determines that no occupant is seated in a seat 20 to which electricity is applied to the seat heater 500, it can display or provide audio guidance to warn that the seat heater switch 200 of a seat 20 in which no occupant is seated has been turned on.
When the seat heater switch 200 is not turned off even after the seat heater control device 300 issues the above-mentioned warning, the seat heater control device 300 can execute a process of reducing the amount of electricity supplied to the seat heater 500 or stopping the supply of electricity.

10...vehicle, 20...seat, 100...seat heater system, 300...seat heater control device, 310...reference heat distribution information acquisition unit, 311...first acquisition unit, 312...second acquisition unit, 313...selection unit, 320...seating detection unit, 330...heater control unit, 500...seat heater, 600...thermo camera

Claims (5)

A seat heater control device for controlling power supply to a seat heater provided in a vehicle seat,
a reference heat distribution information acquisition unit that references a table that associates reference heat distribution information, which is information about a heat distribution in the seat when the seat heater is energized and no occupant is seated in the seat, with a seat position, and obtains the reference heat distribution information corresponding to an actual seat position;
a seating detection unit that detects whether or not an occupant is seated in the seat by comparing the reference heat distribution information obtained by the reference heat distribution information acquisition unit with information on a thermal image including an area heated by the seat heater and captured by a thermal camera;
a heater control unit that controls power supply to the seat heater in response to the presence or absence of an occupant seated on the seat detected by the seating detection unit;
having
The reference heat distribution information acquisition unit
a first acquisition unit that acquires reference heat distribution information stored in the table corresponding to a seat position that is approximate to an actual seat position, as reference heat distribution information at the actual seat position;
a second acquisition unit that performs an interpolation process based on reference heat distribution information stored in the table corresponding to a plurality of seat positions that are close to the actual seat position, to obtain reference heat distribution information at the actual seat position; and
a selection unit that selects one of the first acquisition unit and the second acquisition unit according to a condition of seat occupancy detection by the seat occupancy detection unit, and acquires reference heat distribution information at an actual seat position by the selected acquisition unit;
having
Seat heater control device. 2. The seat heater control device according to claim 1,
The selection unit is
selecting one of the first acquisition unit and the second acquisition unit according to a positional relationship between the thermo camera and the seat;
Seat heater control device. 2. The seat heater control device according to claim 1,
The selection unit is
selects the first acquisition unit when a change in the heated area in the thermal image caused by a change in the seat position of the seat is smaller than a threshold value, and selects the second acquisition unit when a change in the heated area in the thermal image caused by a change in the seat position of the seat is larger than the threshold value.
Seat heater control device. 2. The seat heater control device according to claim 1,
The seat heater is
a seat cushion heater built into the seat surface portion of the seat;
A seat back heater built into the backrest of the seat;
Including,
The selection unit is
selecting one of the first acquisition unit and the second acquisition unit for each of the seat cushion heater and the seat back heater, and acquiring reference heat distribution information for the seat cushion heater and reference heat distribution information for the seat back heater, respectively;
Seat heater control device. 5. The seat heater control device according to claim 4,
The selection unit is
When the installation height of the thermo camera is lower than a predetermined height, the first acquisition unit is selected for the seat cushion heater, and the second acquisition unit is selected for the seat back heater;
When an installation height of the thermo camera is higher than the predetermined height, the second acquisition unit is selected for the seat cushion heater and the seat back heater.
Seat heater control device.