Fatigue assessment device and vehicle including same

Abstract

This fatigue assessment device (10) comprises: a sensor (3) which detects movement of one among a right leg part, a left leg part, a right arm part, a left arm part, and a neck part of a seated person seated on a seat; and a fatigue assessment unit (5a) which assesses a fatigue state of the seated person on the basis of a detection result from the sensor (3).

Description

Fatigue assessment device and vehicle equipped with same

[0001] The present invention relates to a fatigue evaluation device for evaluating the fatigue state of a seat occupant.

[0002] A known example of this type of device is one that evaluates the fatigue state of an occupant of a vehicle seat (see, for example, Patent Document 1). In the device described in Patent Document 1, a first sensor unit and a second sensor unit are arranged a predetermined distance apart in the front-to-rear direction of the seat cushion, detect pressure from the thighs to the knees of the occupant, and determine that the occupant's sense of fatigue is increasing if movement of the entire lower body in the front-to-rear direction is detected based on the detection results.

[0003] Japanese Patent Application Laid-Open No. 2004-168224

[0004] However, the movement of shifting the entire lower body forward and backward is often a conscious movement made when the seated person realizes fatigue and shifts their seat, and the device described in Patent Document 1 makes it difficult to assess the seated person's state of fatigue early on.

[0005] The fatigue assessment device according to one aspect of the present invention includes a sensor that detects the movement of any of the right leg, left leg, right arm, left arm, or neck of a seated person, and a fatigue assessment unit that evaluates the fatigue state of the seated person based on the detection results of the sensor. By detecting the movement of the legs, which are easier to move while seated than the torso and are more likely to undergo unconscious movement, the device can effectively detect the unconscious movement of the seated person, thereby enabling an early assessment of the seated person's fatigue state.

[0006] The seat is installed in a vehicle in which a seated person operates the vehicle by using one of the right leg and the left leg, and the sensor detects the movement of the other of the right leg and the left leg, thereby making it possible to detect unintentional movements of the seated person without being affected by movements associated with driving operations.

[0007] The sensor detects the movement of the right leg and the movement of the left leg, and the fatigue assessment unit assesses the fatigue state based on the greater of the right leg movement and the left leg movement detected by the sensor. In this case, the fatigue state of the seated occupant can be accurately assessed based on the movement of the dominant leg, which is more likely to move than the supporting leg and is more likely to move unintentionally.

[0008] The fatigue assessment unit calculates the amount of change in the center of gravity in at least one of the front-rear and width directions of the seat based on the detection results from the sensor, and assesses the state of fatigue based on the calculated amount of change. By detecting the movement of the legs, etc., which moves around the torso, as the amount of change in the center of gravity in at least one of the front-rear and width directions of the seat, it is possible to effectively detect unconscious movements of the seated occupant.

[0009] The center of gravity position is a coordinate value in at least one of the front-rear direction and the width direction of the seat. By specifying the center of gravity position as a coordinate value in at least one of the front-rear direction and the width direction of the seat, the process of calculating the center of gravity position and the amount of variation can be simplified and the calculation load can be reduced.

[0010] The sensor is a pressure sensor provided on the seating surface of the seat that comes into contact with any of the right leg, left leg, right arm, left arm, and neck, and the fatigue assessment unit assesses the fatigue state based on the detection results of the sensor in a range of the seating surface away from the occupant's torso. By setting the detection range of the sensor to a range away from the occupant's torso, it is possible to preferably detect movements of the legs and other parts of the body that are easier to move while seated than the torso and are more likely to move unintentionally.

[0011] The sensor is a pressure sensor and is located on the other side of the seat surface from the center and away from the buttocks of the occupant. By setting the detection range of the sensor away from the operating leg and buttocks, it is possible to detect unintentional movements of the occupant without being affected by movements associated with driving operations.

[0012] The fatigue assessment unit calculates the amount of variation at a predetermined cycle, performs a smoothing process on the calculated amount of variation to calculate an evaluation value, and assesses the fatigue state based on the calculated evaluation value. In the smoothing process, the current evaluation value is calculated as the sum of the current amount of variation and the previous evaluation value multiplied by a predetermined weighting coefficient. By smoothing the amount of variation, an appropriate evaluation value that represents the gradually changing fatigue state can be calculated, thereby enabling the fatigue state of the seated occupant to be appropriately assessed.

[0013] The fatigue evaluation unit performs a normalization process to normalize the current evaluation value to a value between 0 and 1 based on the ranking of the current evaluation value in a predetermined data group, and evaluates the fatigue state based on the current evaluation value normalized by the normalization process. This allows for a more appropriate evaluation of the fatigue state of the seated occupant.

[0014] The predetermined data group is all the evaluation values ​​calculated for the same seated occupant, which allows for a more appropriate evaluation of the fatigue state of the individual seated occupant.

[0015] The fatigue assessment unit assesses the fatigue state using a logistic regression model, which uses whether the seated occupant is fatigued as the dependent variable and values ​​calculated based on the detection results by the sensor as explanatory variables. In this case, the fatigue state of the seated occupant can be assessed more accurately based on the fatigue probability obtained from the logistic regression model.

[0016] The sensor detects the movement of the left leg, which is easier to move while seated than the torso and is more likely to undergo unconscious movement. By detecting the movement of the left leg, it is possible to effectively detect unconscious movements of the seated person, thereby enabling an early assessment of the seated person's fatigue state.

[0017] The present invention also provides a vehicle equipped with a fatigue assessment device, which allows early assessment of the fatigue state of an occupant seated in a seat.

[0018] According to the present invention, the fatigue state of a seated occupant can be evaluated at an early stage.

[0019] 5 is a diagram showing an example of a seat to which a fatigue assessment device according to an embodiment of the present invention is applied. FIG. 6 is a block diagram showing an example of the overall configuration of a fatigue assessment device according to an embodiment of the present invention. FIG. 7 is a diagram for explaining the detection range of the surface pressure sensor of FIG. 1. FIG. 8 is a diagram for explaining the arrangement of pressure-sensitive elements that constitute the surface pressure sensor of FIG. 1. FIG. 9 is a diagram showing an example of the amount of variation in the center of gravity position calculated based on the detection result by the surface pressure sensor of FIG. 1. FIG. 10 is a diagram for explaining weights used in the process of smoothing the amount of variation in FIG. 5. A flowchart showing an example of processing executed by the controller of FIG. 2. FIG. 11 is a side view showing a schematic configuration of a vehicle seat according to another embodiment of the present invention. FIG. 12 is a diagram showing a main part of a vehicle seat according to another embodiment of the present invention, illustrating an example in which a notch is provided in the front end of a seat cushion of a rear seat to support the underside near the rear end of a leg rest. FIG. 13 is a diagram showing a main part of a vehicle seat according to another embodiment of the present invention, illustrating an example in which the underside near the rear end of a leg rest is supported by the front end of the seat cushion of a rear seat. FIG. 14 is a diagram showing a main part of a vehicle seat according to another embodiment of the present invention, illustrating an example in which the seating position of the rear seat is set high. FIG. 1 is a diagram illustrating the main parts of a vehicle seat according to another embodiment of the present invention, illustrating an example that can accommodate a case where a passenger's legs do not reach the support surface of the leg rest. FIG. 1 is a diagram illustrating the main parts of a vehicle seat according to another embodiment of the present invention, illustrating another example that can accommodate a case where a passenger's legs do not reach the support surface of the leg rest. FIG. 2 is a diagram illustrating the main parts of a vehicle seat according to another embodiment of the present invention, illustrating an example in which the leg rest is used as a seating area. FIG. 3 is a diagram illustrating the main parts of a vehicle seat according to another embodiment of the present invention, illustrating an example in which the leg rest is used as a seating area and the seat cushion is used as a table or storage area. FIG. 4 is a diagram illustrating the main parts of a vehicle seat according to another embodiment of the present invention, illustrating an example in which a light built into the headrest is used when the leg rest is used as a seating area and the seat cushion is used as a table or storage area. FIG. 5 is a diagram illustrating the main parts of a vehicle seat according to another embodiment of the present invention, illustrating the use of interchangeable leg rests of different types in appropriate locations.

[0020] [Fatigue Assessment Device] An embodiment of the present invention will now be described with reference to Figures 1 to 7. A fatigue assessment device according to an embodiment of the present invention assesses the fatigue state, including the degree of fatigue and the degree of decline in concentration, of an occupant who sits in a seat and maintains a constant seated posture for a long period of time. For example, the fatigue state of an occupant who is a driver operating a vehicle such as a car, an occupant who is a passenger restrained by a seat belt or the like, an occupant who is a worker performing a specific task such as work or gaming, or an occupant undergoing a medical examination or treatment will be evaluated. An example of assessing the fatigue state of an occupant who is a driver of an automatic transmission (AT) vehicle will be described below.

[0021] 1 is a diagram showing an example of a seat 1 to which a fatigue assessment device according to an embodiment of the present invention is applied, and shows the seat 1 as a driver's seat installed in the driver's seat of a vehicle 2 that is an automatic transmission vehicle. As shown in FIG. 1, the seat 1 has a seat cushion 1a that supports the buttocks of the seated driver, a seat back 1b that supports the lower back and back, and a headrest 1c that supports the head. In the following, the front-to-rear direction, left-to-right direction, and up-to-down direction are defined as shown in the figure with respect to the seated driver seated in the seat 1, and the configuration of each part will be described according to these definitions.

[0022] The seat cushion 1a extends in the front-rear and left-right directions and has a generally rectangular shape when viewed from above. The seat back 1b and headrest 1c extend in the up-down and left-right directions and have a generally rectangular shape when viewed from the front. The upper side of the seat back 1b and headrest 1c corresponds to the rear, the lower side corresponds to the front, and the up-down direction corresponds to the front-to-back direction. The upper surface of the seat cushion 1a and the front surface of the seat back 1b and headrest 1c form a seating surface. The seat cushion 1a is provided with a surface pressure sensor 3 that detects the load on the seating surface (body pressure, seat pressure, applied from the seating surface to the body surface of the seated person). The body movement of the seated person can be detected based on the detection results of the surface pressure sensor 3.

[0023] In the cabin of the vehicle 2, operation pedals (accelerator pedal and brake pedal) 3 for driving operations are provided in front of the seat 1. The driver operates the operation pedal 4 with his right foot to drive the vehicle 2. In this case, the right leg (operating side leg) that performs the driving operation moves in response to the driving operation of the right foot, but the left leg (non-operating side leg) that does not perform the driving operation hardly moves.

[0024] When an occupant sitting on seat 1 maintains a fixed seating posture for a long period of time, body pressure concentrates on the seating surface, gradually leading to fatigue and a decline in concentration. When an occupant becomes aware of fatigue or a decline in concentration, they tend to consciously change their position, such as by reseating their seat. However, even before they become aware of fatigue or a decline in concentration, they tend to unconsciously move parts of their body that are in contact with the seating surface (in other words, unconscious movements (body movements) occur) in order to relieve the concentration of body pressure. Therefore, in this embodiment, a fatigue assessment device is configured as follows to detect such unconscious movements and enable early assessment of the occupant's fatigue state.

[0025] Fig. 2 is a block diagram showing an example of the overall configuration of a fatigue assessment device (hereinafter referred to as device) 10 according to an embodiment of the present invention. As shown in Fig. 2, the device 10 includes the surface pressure sensor 3 of Fig. 1 and a controller 5 that functions as a fatigue assessment unit 5a that assesses the fatigue state of a seated occupant based on the detection results of the surface pressure sensor 3. The surface pressure sensor 3 is connected to the controller 5, and the detection results of the surface pressure sensor 3 are input to the controller 5.

[0026] The controller 5 includes a computer having a processor such as a CPU, memories such as RAM and ROM, and other peripheral circuits, and is provided inside the seat 1, for example, as shown in Fig. 1. The controller 5 may also be provided outside the seat 1. Based on the detection results from the surface pressure sensor 3, the controller 5 detects the body movements of the occupant who is seated in the seat 1 and operates the vehicle 2, particularly the movements of the legs on the non-operating side.

[0027] 3 is a diagram illustrating the detection range of the surface pressure sensor 3, showing the seating surface of the seat cushion 1a as viewed from above. As shown in Fig. 1 and Fig. 3, of the seating surface of the seat cushion 1a, the rear area AR1 is mainly in contact with the buttocks of the seated occupant and receives a load from the buttocks, the right front area AR2 is mainly in contact with the operating side leg and receives a load from the operating side leg, and the left front area AR3 is mainly in contact with the non-operating side leg and receives a load from the non-operating side leg.

[0028] The rear area AR1 is the area that comes into contact with the buttocks, which are part of the torso of the seated occupant, while the right front area AR2 and the left front area AR3 are areas that are further forward than the rear area AR1, i.e., away from the torso (buttocks) of the seated occupant. The right front area AR2 is an area that is closer to the operating-side leg than the center of the seat surface of the seat 1, and the left front area AR3 is an area that is closer to the non-operating-side leg than the center of the seat surface of the seat 1. The surface pressure sensor 3 is provided in the left front area AR3 so that it can detect movement of the non-operating-side leg via the load from the non-operating-side leg.

[0029] The legs, arms, and neck are more easily moved while seated than the torso, and are more likely to undergo unintentional movements by the seated person. By setting the detection range of the surface pressure sensor 3 to a range away from the seated person's torso, the seated person's unintentional movements can be detected effectively. Furthermore, by setting the detection range of the surface pressure sensor 3 to a range away from the operating-side legs and buttocks, the seated person's unintentional movements can be accurately detected without being affected by movements associated with driving operations. That is, by individually detecting the movements of the right leg, left leg, right arm, left arm, and neck (e.g., the non-operating-side legs), which are more likely to undergo unintentional movements by the seated person, and performing independent evaluations based on the movements of each part, the seated person's fatigue state can be accurately evaluated.

[0030] FIG. 4 is a diagram for explaining the arrangement of pressure-sensitive elements that make up the surface pressure sensor 3. As shown in FIG. 4, the surface pressure sensor 3 has a plurality of pressure-sensitive elements (for example, M×N (M, N: arbitrary natural numbers, M=N=8 in the example of FIG. 4)), and detects the pressure distribution in the left front area AR3. Each pressure-sensitive element is assigned a coordinate value i in the width direction (left-right direction) of the seat 1, 0, 1, ..., M-2, M-1 (0, 1, ..., 7 in the example of FIG. 4), from the right, and a coordinate value j in the depth direction (front-rear direction) of the seat 1, 0, 1, ..., N-2, N-1 (0, 1, ..., 7 in the example of FIG. 4), from the front, ij is input to the controller 5 in FIG. 2 at a predetermined period T1 (for example, 0.1 seconds).

[0031] The fatigue evaluation unit 5a (controller 5) calculates the amount of change σ of the center of gravity G in at least one of the front-rear direction and the width direction of the seat 1, for example, in the width direction, based on the detection results of the surface pressure sensor 3, and evaluates the fatigue state of the seated occupant based on the calculated amount of change σ. More specifically, first, the pressure distribution P detected by the surface pressure sensor 3 is calculated at a predetermined period T1. ij Based on this, the center of gravity position G is calculated as a coordinate value i in the width direction of the seat 1 using the following formula (i): By specifying the center of gravity position G as a coordinate value i in at least one of the front-rear direction and width direction of the seat 1, the process of calculating the center of gravity position G and the amount of variation σ can be simplified, and the calculation load can be reduced.

[0032] Unintentional movements of the seated person that occur in the legs, arms, and neck, which move around the torso, tend to occur mainly as movements in the width direction of the seat 1. By individually detecting the movements of the right leg, left leg, right arm, left arm, and neck (for example, the legs on the non-operating side) in the width direction of the seat 1, it is possible to accurately detect unintentional movements of the seated person without being affected by movements of the torso. Furthermore, by detecting the movements of the legs on the non-operating side as the amount of change σ of the center of gravity position G in the width direction of the seat 1, it is possible to suitably detect unintentional movements of the seated person. Furthermore, the pressure distribution P ijBy setting the detection period and the calculation period of the center of gravity position G (i.e., the predetermined period T1) to be sufficiently short, it is possible to detect momentary and fine movements, and to accurately detect unconscious movements of the seated person.

[0033] Next, the fatigue evaluation unit 5a calculates the average center-of-gravity position Ga for the current period (predetermined period T2) using the following formula (ii) at a predetermined period T2 (e.g., 60 seconds) based on the center-of-gravity position G calculated for each predetermined period T1. Then, using the following formula (iii), the fatigue evaluation unit 5a calculates the standard deviation of the coordinate value i based on the average center-of-gravity position Ga for the current period as the amount of fluctuation σ of the center-of-gravity position G in the width direction of the seat 1. The amount of fluctuation σ of the center-of-gravity position G in the left front area AR3 corresponds to the magnitude of movement of the non-operating leg.

[0034] 5 is a diagram showing an example of the amount of variation σ of the center of gravity position G calculated based on the detection results of the surface pressure sensor 3. As shown in FIG. 5, the amount of variation σ calculated for each predetermined period T2 represents the magnitude of the movement of the non-operating side leg in each period, and therefore changes discontinuously over time. The fatigue evaluation unit 5a performs a smoothing process on this amount of variation σ to calculate an evaluation value X that represents the fatigue state that gradually changes over time. More specifically, the current amount of variation σ is calculated as shown in the following formula (iv): n and the previous evaluation value X multiplied by a predetermined weighting coefficient k (0<k<1). n-1 The sum of this is the current evaluation value X n The amount of variation σ is smoothed to obtain an appropriate evaluation value X that represents a gradually changing fatigue state, thereby making it possible to appropriately evaluate the fatigue state of the seated occupant.

[0035] FIG. 6 is a diagram illustrating weights used in the smoothing process, and shows the fluctuation amount σ calculated for each predetermined period T2. m A weight k according to the time delay (n-m) is multiplied by n-m As shown in formula (iv) and FIG. 6, the current (nth) evaluation value X n is the amount of fluctuation σ calculated up to this time (m times (m=1, 2, . . . , n-2, n-1, n)). mThe weight k decreases as the time lag (nm) increases. n-m Multiply these products k n-mσ m In this way, it is possible to calculate the evaluation value X that represents the fatigue state, which gradually changes over time.

[0036] The fatigue evaluation unit 5a further calculates the current evaluation value X n Based on the ranking, the current evaluation value X n is normalized to a percent rank value α between 0 and 1 (the current evaluation value X n is the minimum value, it is "0", and is the maximum value, it is "1". The predetermined data group is, for example, all the evaluation values ​​X calculated for the same occupant, for example, all the evaluation values ​​X calculated after the occupant's seating on the seat 1 is detected based on the detection result of the surface pressure sensor 3. If the individual occupant can be identified, all the evaluation values ​​X calculated when the same occupant previously sat on the seat 1 are set as the predetermined data group. By taking into account the past evaluation values ​​X of the same occupant, it is possible to calculate a percentage rank value α that appropriately represents the fatigue state of the individual occupant.

[0037] The fatigue evaluation unit 5a uses a predetermined judgment formula stored in advance in the memory of the controller 5 to calculate the current evaluation value X nThe fatigue probability corresponding to the percent rank value α of the seat 1 is calculated. The predetermined judgment formula is created in advance using a trained logistic regression model with the objective variable being whether the seat occupant is fatigued (fatigued or not) or whether their concentration is declining (declining or not declining) and the normalized evaluation value X (percent rank value α) being the explanatory variable. The fatigue state of the seat occupant is then evaluated by determining whether the calculated fatigue probability is equal to or greater than a predetermined threshold (e.g., 0.5) as being fatigued (or declining concentration), and whether the calculated fatigue probability is less than the threshold as not being fatigued (or not declining concentration). This allows for more accurate evaluation of the seat occupant's fatigue state. By using the normalized evaluation value X (percent rank value α), an appropriate fatigue probability can be calculated even when the seat occupant being evaluated for fatigue differs from the seat occupant when the judgment formula was created, thereby allowing for more accurate evaluation of the seat occupant's fatigue state.

[0038] 7 is a flowchart showing an example of processing executed by the controller 5. The processing shown in this flowchart is started, for example, when the vehicle 2 is started and power is supplied to the surface pressure sensor 3 and the controller 5, and is repeated at a predetermined cycle T1. As shown in FIG. 7, first, in step S1, the pressure distribution P detected by the surface pressure sensor 3 is calculated. ij Next, in step S2, the pressure distribution P ij The center of gravity G in the width direction of the seat 1 is calculated based on the above equation (2). The center of gravity G calculated in step S2 is stored and accumulated in the memory of the controller 5 as time-series data for a predetermined period T1.

[0039] Next, in step S3, it is determined whether the predetermined period T2 has elapsed. If the result in step S3 is affirmative, the process proceeds to step S4, and if the result is negative, the current process is terminated. In step S4, the average center-of-gravity position Ga and the amount of fluctuation σ of the center-of-gravity position G in the current period (predetermined period T2) are calculated based on the center-of-gravity positions G for the predetermined period T1 stored in memory. The amount of fluctuation σ calculated in step S4 is stored and accumulated in the memory of the controller 5 as time-series data for the predetermined period T2.

[0040] Next, in step S5, a smoothing process is performed on the fluctuation amount σ for the predetermined period T2 stored in the memory, and an evaluation value X of the fatigue state for the current period (predetermined period T2) is calculated. The evaluation value X calculated in step S5 is stored and accumulated in the memory of the controller 5 as time-series data for the predetermined period T2.

[0041] Next, in step S6, the current evaluation value X is normalized based on the ranking of all evaluation values ​​X stored in memory to calculate a percent rank value α. The percent rank value α calculated in step S6 is stored and accumulated in the memory of the controller 5 as time-series data for a predetermined period T2.

[0042] Next, in step S7, a predetermined judgment formula pre-stored in the memory of controller 5 is used to calculate the fatigue probability corresponding to the percent rank value α calculated in step S6. Next, in step S8, it is determined whether the fatigue probability calculated in step S7 is equal to or greater than a predetermined threshold value (e.g., 0.5). If the result in step S8 is affirmative, the process proceeds to step S9, where the fatigue state of the seated occupant is evaluated as "fatigued" (or "decline in concentration"). If the result in step S8 is negative, the process proceeds to step S10, where the fatigue state of the seated occupant is evaluated as "not fatigued" (or "not decline in concentration").

[0043] Thus, by detecting the movement of the legs, which are more easily moved and more prone to unintentional movement while seated than the torso, as the fluctuation σ of the center of gravity G (steps S1 to S4), it is possible to effectively detect the seated occupant's unintentional movements and thereby evaluate the seated occupant's fatigue state early. Furthermore, by smoothing the fluctuation σ, it is possible to calculate an appropriate evaluation value X that represents gradually changing fatigue states, thereby enabling an appropriate evaluation of the seated occupant's fatigue state (step S5). Furthermore, by normalizing the evaluation value X based on the same seated occupant's past evaluation values ​​X, etc., it is possible to calculate a percent rank value α that appropriately represents the individual seated occupant's fatigue state, thereby enabling an even more appropriate evaluation of the seated occupant's fatigue state (step S6). Furthermore, by calculating the fatigue probability corresponding to the evaluation value X (percent rank value α) using a predetermined judgment formula pre-stored in the memory of the controller 5 and evaluating the fatigue state based on the calculated fatigue probability, the evaluation accuracy can be further improved (steps S7 to S10).

[0044] The evaluation results of the seated person's fatigue state can be output and utilized in various ways. For example, when the seated person is evaluated as being fatigued or having difficulty concentrating, a voice announcement or other notification may be issued. By evaluating the fatigue state and issuing a notification at an early stage before the seated person becomes aware of fatigue or a decrease in concentration, it becomes possible to take appropriate measures such as taking a break at an appropriate time. Specific suggestions such as appropriate break times may also be made.

[0045] When the seat 1 is evaluated as having fatigue or reduced concentration, equipment installed in or around the seat 1 (e.g., the cabin of the vehicle 2) may be activated to alleviate the fatigue of the occupant or restore their concentration. Suitable examples of such equipment include a massage equipment installed in the seat 1, a ventilation equipment, an aroma spray equipment installed in or around the seat 1, a sound equipment, and a ventilation equipment or air conditioning equipment installed around the seat 1. When equipment is activated in response to the fatigue state evaluation result, it is preferable to provide an appropriate switch so that a user (the occupant or nearby people) can enable or disable the operation of each piece of equipment. It is preferable that the switch operation for enabling or disabling the operation of each piece of equipment be accepted when the controller 5 is started (when the fatigue state evaluation starts) and also be accepted after the equipment has been activated in response to the fatigue state evaluation result.

[0046] The time-series evaluation value X (or the amount of variation σ of the center-of-gravity position G or the percentage rank value α of the evaluation value X) as shown in FIG. 5 may be output so that the occupant or those around them can check it. For example, it may be transmitted to the vehicle 2 so that it is displayed on an in-vehicle display, or it may be transmitted to the occupant's own user terminal, such as a smartphone or wearable device, so that the occupant can manage it themselves. In this case, the occupant can use the fatigue state evaluation result as one of their own vital signs.

[0047] The embodiment of the present invention can achieve the following advantageous effects: (1) The device 10 includes a surface pressure sensor 3 that detects the movement of the left leg (non-operating leg) of an occupant seated on the seat 1, and a fatigue evaluation unit 5a that evaluates the fatigue state of the occupant based on the detection results of the surface pressure sensor 3 (FIGS. 1 to 3). By detecting the movement of the legs, which are more likely to move while seated than the torso and are more likely to undergo unintentional movement, it is possible to effectively detect the occupant's unintentional movements, thereby enabling an early evaluation of the occupant's fatigue state.

[0048] (2) The seat 1 is a driver's seat mounted on the vehicle 2, which is an automatic transmission vehicle, in which the occupant operates the vehicle using their right leg (operating leg), and the surface pressure sensor 3 detects the movement of the left leg (non-operating leg) of the occupant who is the driver of the vehicle 2 (FIGS. 1 and 3). This makes it possible to detect unintentional movements of the occupant without being affected by movements associated with driving operations.

[0049] (3) The fatigue evaluation unit 5a calculates the amount of variation σ of the center of gravity G in at least one of the front-rear direction and width direction (left-right direction) of the seat 1 based on the detection results of the surface pressure sensor 3, and evaluates the fatigue state of the seated occupant based on the calculated amount of variation σ ( FIGS. 3 to 5 ). By detecting the movement of the legs and other parts of the body centered on the trunk as the amount of variation σ of the center of gravity G in at least one of the front-rear direction and width direction of the seat 1, unconscious movements of the seated occupant can be suitably detected.

[0050] (4) The center of gravity position G is a coordinate value i in at least one of the front-rear direction and the width direction of the seat 1 (FIG. 4). By specifying the center of gravity position G as a coordinate value i in at least one of the front-rear direction and the width direction of the seat 1, the process of calculating the center of gravity position G and the amount of variation σ can be simplified and the calculation load can be reduced.

[0051] (5) The surface pressure sensor 3 is provided on the seating surface of the seat 1 (seat cushion 1a) where the non-operating leg contacts. The fatigue evaluation unit 5a evaluates the occupant's fatigue state based on the detection results of the surface pressure sensor 3 in a region of the seating surface away from the occupant's torso (buttocks) ( FIGS. 1 , 3 , and 4 ). The surface pressure sensor 3 is provided closer to the non-operating leg than the center of the seating surface of the seat 1 and away from the occupant's buttocks ( FIGS. 1 , 3 , and 4 ). By setting the detection range of the surface pressure sensor 3 away from the occupant's torso, it is possible to effectively detect movements of the legs and other parts of the body, which are more easily moved while seated than the torso and are more likely to be unintentionally moved by the occupant. Furthermore, by setting the detection range of the surface pressure sensor 3 away from the operating leg and buttocks, it is possible to detect unintentional movements of the occupant without being affected by movements associated with driving operations.

[0052] (6) The fatigue evaluation unit 5a calculates the amount of fluctuation σ of the center-of-gravity position G at a predetermined period T2 (for example, 60 seconds), and calculates an evaluation value X by performing a smoothing process on the calculated amount of fluctuation σ, and evaluates the fatigue state of the seated occupant based on the calculated evaluation value X (step S5 in FIGS. 5 and 7). n and the previous evaluation value X multiplied by a predetermined weighting coefficient k. n-1 The sum of this is the current evaluation value X n is calculated (FIG. 6). By smoothing the variation σ, it is possible to calculate an appropriate evaluation value X that represents the gradually changing fatigue state, thereby making it possible to appropriately evaluate the fatigue state of the seated occupant.

[0053] (7) The fatigue evaluation unit 5a calculates the current evaluation value X n Based on the ranking, the current evaluation value is X n is normalized to a percent rank value α between 0 and 1, and the normalized evaluation value X n The fatigue state of the seated occupant is evaluated based on the percent rank value α, which is expressed as: (Step S6 in FIG. 7). The predetermined data group is, for example, all the evaluation values ​​X calculated for the same seated occupant. In this case, it is possible to calculate a percent rank value α that appropriately represents the fatigue state of the individual seated occupant, thereby enabling a more appropriate evaluation of the seated occupant's fatigue state.

[0054] (8) The fatigue evaluation unit 5a evaluates the fatigue state of the seated person using a logistic regression model in which whether the seated person is tired (or whether their concentration has decreased) is the objective variable and the percent rank value α calculated based on the detection results of the surface pressure sensor 3 is the explanatory variable (steps S7 to S10 in FIG. 7). In this case, the fatigue state of the seated person can be evaluated more accurately based on the fatigue probability obtained from the logistic regression model.

[0055] In the above embodiment, an example in which the device 10 is applied to the seat 1, which is the driver's seat of the vehicle 2, which is an automatic transmission vehicle, has been described with reference to Figure 1 and other figures. However, the seat to which the fatigue assessment device can be applied is not limited to this. For example, the device can be applied to any seat in which the occupant maintains a constant seating posture for an extended period of time, such as a passenger seat in a vehicle, a seat for a vehicle other than a vehicle, a work seat other than a vehicle (e.g., an office chair or a gaming chair), or a medical seat. Note that when performing a slow task, such as simply sitting in the seat 1, the amount of fluctuation σ in the center of gravity position G is greater than when performing a task requiring concentration, such as driving, and thus fatigue and a decrease in concentration are more likely to occur.

[0056] 1 and the like in the above embodiment, the surface pressure sensor 3 is provided on the seat 1, which is the driver's seat of the vehicle 2, which is an automatic transmission vehicle, and detects the movement of the left leg (non-operating leg) of the driver who operates the vehicle using the right leg (operating leg). However, the sensor for detecting the movement of any of the right leg, left leg, right arm, left arm, and neck of the occupant sitting in the seat is not limited to this. In other words, any sensor may be used as long as it detects the movement of a part of the legs, arms, and neck that moves around the torso of the occupant and is not consciously moved by the occupant, that is in contact with the seating surface of the seat 1, and that does not move much when the occupant is operating the vehicle, performing a specific task, or receiving a medical examination or treatment.

[0057] In the above embodiment, an example has been described in which the amount of variation σ of the center of gravity position G in the width direction of the seat 1 is calculated, but the amount of variation in the center of gravity position can be calculated as the amount of variation in the center of gravity position in at least one of the front-rear direction and width direction of the seat, and it is also possible to calculate the amount of variation σ of the center of gravity position G in the front-rear direction of the seat 1. In other words, when a person is seated in the seat 1, the positions of the legs, arms, and neck are restricted to some extent depending on the shape of the seat 1, making it difficult to move them in the front-rear direction, but depending on the structure of the seat 1 and the area around the seat 1 and the physique of the person seated, it may be easy to move each part in the front-rear direction.

[0058] In the above embodiment, an example was described in which the fatigue state of an occupant is evaluated based on the detection results of the movement of the occupant's left leg in the seat width direction. However, the fatigue state of an occupant may also be evaluated based on, for example, the movement of the right leg in the seat width direction and the movement of the left leg in the seat front-to-rear direction.

[0059] The part of the body whose movement is detected by the sensor may be fixed to any one of the right leg, left leg, right arm, left arm, and neck in advance, or may be user-configurable or switchable as appropriate depending on the analysis results. For example, the part may be switched depending on how easily each seated occupant's fatigue manifests itself in their body movements. The part of the body whose movement is detected by the sensor may be a single part of the right leg, left leg, right arm, left arm, and neck, or multiple parts. Even when detecting the movements of multiple parts, the seated occupant's fatigue state is evaluated based on the movements of each part, and the evaluations based on the movements of each part are performed independently of each other. For example, even when detecting the movements of the right leg and the left leg, the seated occupant's fatigue state is evaluated based on the movements of the right leg and the left leg, and the evaluations based on the movements of the right leg and the left leg are performed independently of each other.

[0060] When evaluating the fatigue state of a seated occupant who is a driver of a vehicle 2 that can switch between manual and automatic driving modes, the evaluation may be performed based on the movement of the non-operating leg in the manual driving mode, and the evaluation may be performed based on the movement of the right and left legs in the automatic driving mode. When evaluating the fatigue state of a seated occupant who is a passenger of a vehicle 2 with a changeable seat arrangement, the body part for detecting movement may be switched depending on the seat arrangement. That is, for a driver's seated occupant, in the manual driving mode, it is determined that the occupant is performing a driving operation, which requires concentration, while in the automatic driving mode, it is determined that the occupant is simply performing the slow task of sitting in the seat 1. Furthermore, depending on the seat arrangement, it may be determined whether the body part most likely to make an unconscious movement of the occupant is the right leg, left leg, right arm, left arm, or neck, or whether the direction most likely to make an unconscious movement of the occupant is the front-to-back direction or the width direction of the seat 1, and the body part and direction for detecting movement may be switched depending on the determination result.

[0061] The sensor is not limited to a sensor that detects pressure, and may be any sensor that detects unconscious movements of the seated occupant that occur in these areas, primarily to relieve the concentration of body pressure. For example, a vibration sensor provided in the seat 1 or a sensor that captures images of movements of various parts using a camera provided outside the seat 1 and detects the movements through image processing may be used.

[0062] In the above embodiment, the seat 1 having the seat cushion 1a, the seat back 1b, and the headrest 1c is illustrated in Fig. 1 etc., but the seat may also have a footrest for supporting the legs of the seated occupant, armrests for supporting the arms, etc. The seat may also have only the seat cushion 1a and the seat back 1b, or only the seat cushion 1a.

[0063] In the above embodiment, an example in which the surface pressure sensor 3 is provided only in the left front area AR3 and detects only the movement of the left leg, which is the non-operating leg, has been described with reference to FIG. 3 and other figures. However, the sensor may also detect the movement of the right leg (load P applied to the right front area AR2) and the movement of the left leg (load P applied to the left front area AR3). In this case, the fatigue evaluation unit 5a may evaluate the fatigue state of the seated occupant based on the larger of the movement of the right leg and the movement of the left leg detected by the surface pressure sensor 3. That is, among the legs, arms, and neck, which move around the torso of the occupant and are unconsciously moved by the occupant, if there are multiple parts that are in contact with the seating surface of the seat 1 and hardly move at all without driving, performing a specific task, or receiving medical treatment, the magnitude of movement of each part may be detected, and the fatigue state of the occupant may be evaluated based on the movement of the part with the largest detected movement. For example, surface pressure sensors 3 may be provided in the right front area AR2 and the left front area AR3 of the seat 1 (seat cushion 1a) serving as a passenger seat, and the magnitude of movement of the left and right legs may be detected, and the fatigue state of the seated occupant may be evaluated based on the larger of the two movements. In this case, the fatigue state of the seated occupant can be accurately evaluated based on the movement of the dominant leg, which is more likely to move than the pivot leg and is more likely to make unconscious movements.

[0064] In the above embodiment, an example has been described in which the fatigue probability is calculated using a discriminant created using a trained logistic regression model with whether or not the occupant of seat 1 is fatigued as the objective variable and the percentage rank value α of the evaluation value X as the explanatory variable. However, the fatigue probability may also be calculated using a discriminant created using another regression model, such as a support vector machine, instead of the logistic regression model.

[0065] In the above embodiment, an example is described in which a seated occupant's fatigue state is evaluated by calculating a fatigue probability (step S7) and comparing the calculated fatigue probability with a single threshold value to determine whether or not the occupant is fatigued or has lost concentration, as illustrated in FIG. 7 and other figures. However, the fatigue evaluation by the fatigue evaluation device is not limited to this. For example, the seated occupant's fatigue state may be evaluated by comparing the calculated fatigue probability with multiple threshold values ​​to identify the degree of fatigue (e.g., three levels: mild, moderate, and severe). Furthermore, the fatigue state may be evaluated by comparing the amount of fluctuation σ of the center of gravity position G calculated in step S4 with a predetermined threshold value. The fatigue state may be evaluated by comparing the smoothed evaluation value X calculated in step S5 with a predetermined threshold value. The fatigue state may be evaluated by comparing the normalized evaluation value X (percent rank value α) calculated in step S6 with a predetermined threshold value.

[0066] In the above embodiment, specific numerical values ​​have been exemplified for the predetermined period T1 for acquiring the sensor value of the surface pressure sensor 3 to calculate the center of gravity position G, and the predetermined period T2 for calculating the amount of fluctuation σ of the center of gravity position G, smoothing, normalizing, calculating the fatigue probability, and evaluating the fatigue state. However, these are merely examples and are not limited to the exemplified values. The period for performing each process may be a fixed value, may be user-settable, or may be reconfigurable as appropriate depending on the analysis results. For example, the period may be set depending on how easily fatigue manifests itself in the body movements of each seated occupant.

[0067] [Vehicle Seat] Next, another embodiment of the present invention will be described with reference to Figures 8 to 17. The vehicle seat according to the embodiment of the present invention is a vehicle seat to which the fatigue evaluation device described above can be applied, but can also be used without applying the fatigue evaluation device.

[0068] A known device is a seatbelt that supports the lumbar area of ​​a front-seat passenger by removing the part that supports the lumbar area of ​​the front seat and attaching it to the rear of the front seat back to support the calf area of ​​a rear-seat passenger from below, allowing the rear-seat passenger to stretch their legs and maintain a comfortable posture. The part that supports the calf area of ​​the passenger, i.e., the area below the knees, is sometimes called an ottoman.

[0069] However, if the rear end of an ottoman attached to the back of the front seat back is located lower than the front end of the seat cushion of the rear seat on which the passenger using the ottoman sits, the length of the section from near the rear end of the ottoman to the front end of the seat cushion of the rear seat that cannot support the lower part of the knees becomes longer, and the passenger's legs cannot be supported stably.

[0070] Therefore, in this embodiment, the vehicle seat is configured as follows so as to provide a vehicle seat that can stably support the lower knee area of ​​the passenger.

[0071] The vehicle seat according to the embodiment of the present invention is a seat equipped with an ottoman device (leg rest portion) on which the legs of a passenger seated in the seat device are placed, and can be applied to various types of seats. In the following, an example in which the vehicle seat equipped with an ottoman device is applied to a vehicle seat, for example, will be described.

[0072] Fig. 8 is a side view of a vehicle seat equipped with an ottoman device according to an embodiment of the present invention. For convenience, the left-right direction in the figure is defined as the horizontal direction, and the up-down direction is defined as the vertical direction, and each part will be described according to these definitions. The horizontal direction, vertical direction, and directions perpendicular to the paper surface in Fig. 8 correspond to the front-rear direction, height direction, and width direction of the vehicle to which the vehicle seats (front seat 100, rear seat 200) are attached, respectively. The same applies to Figs. 9 to 17, which will be referred to later.

[0073] As shown in FIG. 8 , the vehicle seat includes a front seat 100 for seating a front passenger P1 and a rear seat 200 for seating a rear passenger P2. The front seat 100 and the rear seat 200 are fixed to a pair of left and right rails R fixed to the vehicle body below the seats 100, 200 and spaced apart in the width direction of the seats 100, 200, so as to be slidable in the front-to-rear direction. In a vehicle with two rows of seats, the front seat 100 can be a front seat and the rear seat 200 can be a rear seat. In a passenger vehicle with three rows of seats, the front seat 100 can be a front seat and the rear seat 200 can be a mid-seat located in the second row, or the front seat 100 can be a mid-seat and the rear seat 200 can be a third-row seat. In addition, in a vehicle with three or more rows of seats, such as a bus, any seat other than the last row of the vehicle can be designated as a front seat 100, and the seat located behind that seat can be designated as a rear seat 200.

[0074] The front seat 100 has a seat cushion 104 that supports the thighs of the front passenger P1, and a seat back 102 that is rotatable (reclinable) relative to the seat cushion 104 and supports the back of the front passenger P1. Note that if the front seat 100 is a bucket seat type, the reclining function may be omitted and the seat back 102 may be erected at the rear of the seat cushion 104.

[0075] A seat height adjustment mechanism 130 is provided below the seat cushion 104, which can adjust the height of the front seat 100 to suit the physique of the front passenger P1. The front seat 100 is also provided with an armrest 120. An operating unit 122 is provided on the upper surface of the armrest 120, i.e., on the part where the front passenger P1 places his or her forearm, and can be used to set various functions of the front seat 100, such as the seat height and posture, seat heater, seat ventilation, massage function, etc.

[0076] A leg rest 106 serving as an ottoman device is provided on the rear side (rear) of the seat back 102. When in use, the leg rest 106 functions as an ottoman device that supports the knees LL of the rear passenger P2. As an example, the leg rest 106 is rotatably attached to a rotation shaft 110 provided in the seat back 102 and is stored in a recess 103 formed in the rear of the seat back 102 when not in use. An air cell 108 may be disposed within the leg rest 106. The air cell 108 may be a fluid bag that expands when a fluid, such as air, is pressurized by a pump and sent into the air cell 108 and contracts when the air is discharged. Inflating and deflating the air cell 108 can achieve a height adjustment function and a massage function for the support surface 105 that forms the upper surface of the leg rest 106 when in use.

[0077] The rear seat 200 has a seat cushion 204 that supports the thighs of the rear passenger P2, and a seat back 202 that is rotatable (reclinable) relative to the seat cushion 204 and supports the back of the rear passenger P2. As explained for the front seat 100, if the rear seat 200 is a bucket seat type, the reclining function may be omitted and the seat back 202 may be provided upright at the rear of the seat cushion 204. The same applies to rear seats that do not have a reclining function.

[0078] A seat height adjustment mechanism 230 is provided below the seat cushion 204, which can adjust the height of the rear seat 200 to suit the physique of the rear passenger P2. An armrest 220 is also provided on the side of the seat back 202 via a rotating shaft 224 that extends in the width direction of the vehicle. An operating unit 222 is provided on the upper surface of the armrest 220, i.e., the portion where the rear passenger P2 places their forearm, and can be used to set various functions of the rear seat 200, such as the seat height and position, seat heater, seat ventilation, massage function, etc.

[0079] Armrest 220 is configured to be rotatable about a rotation axis 224. The angular position (tilt) of armrest 220 relative to seat back 202 can be configured to be electrically changeable, for example, by operating operation unit 222. Alternatively, a mechanism for locking armrest 220 from rotating about rotation axis 224 can be provided, and the tilt of armrest 220 can be adjusted by lifting or lowering the front side of armrest 220 while operating an unlock operation member provided on armrest 220.

[0080] The armrest 220 is configured so that its upper surface 226, i.e., the support surface on which the forearm of the rear passenger P2 rests when in use, can be rotated downward toward the front of the vehicle to a stowed position. In other words, the armrest 220 can be rotated in the opposite direction to the flip-up type to reach the stowed position, i.e., to an angular position where the upper surface 226 of the armrest 220 and the seating surface 203 of the seat back 202 are substantially parallel. Therefore, even when the seat back 202 is reclined to a nearly horizontal angle, the upper surface 226 of the armrest 220 can continue to face the rear passenger P2, allowing the rear passenger P2 to maintain a comfortable posture and maintaining good operability when operating the operating unit 222. Furthermore, even when the armrest 220 is lowered to the stowed position, the rear passenger P2 can easily operate the operating unit 222.

[0081] The seat cushion 204 is rotatably connected to the seat height adjustment mechanism 230 via a rotation shaft 242 provided near the rear end thereof. A cyber angle adjustment mechanism 240 is connected near the front end of the seat cushion 204. The cyber angle adjustment mechanism 240 is a mechanism that uses a linear cylinder unit, a link mechanism, or the like to raise and lower the front end of the seat cushion 204. The cyber angle of the rear passenger can be adjusted by rotating the seat cushion 204 around the rotation shaft 242 as the rotation center and adjusting the inclination of the seating surface 206 with respect to the horizontal plane.

[0082] In the vehicle seat configured as described above, when the leg rest portion 106 stored in the recess 103 is pulled out and rotated clockwise in Fig. 8 around the rotation shaft 110, a rotation stopper provided near the rotation shaft 110 positions the leg rest portion 106 at an angular position for use. The state shown in Fig. 8 is the used state of the leg rest portion 106. In the used state, the support surface 105 provided on the upper surface of the leg rest portion 106 is located at the highest position of the support surface 105 on the rear end portion 107 side of the leg rest portion 106.

[0083] When not in use, the leg rest section 106 can be flipped up around the pivot shaft 110 as the center of rotation, in the opposite manner to that described above, and stored in the recess 103 of the seat back 102. Alternatively, the leg rest section 106 may be configured to be removably inserted into the rear surface of the seat back 102. In this case, the leg rest section 106 can be configured to be in the above-described use state when an insertion protrusion provided on the front side of the leg rest section 106 is inserted into a receptacle formed on the rear surface of the seat back 102.

[0084] In the above-described use state, it is desirable that the leg rest portion 106 and the seat cushion 204 of the rear seat 200 abut against each other as shown in Fig. 8. In the example shown in Fig. 8, the rear end portion 107 of the leg rest portion 106 and the front end portion 205 of the seat cushion 204 abut against each other.

[0085] 9 and 10 are side views showing modified examples of the vehicle seat according to the embodiment of the present invention, in which the front occupant P1 and the rear occupant P2 shown in Fig. 8 are omitted. In Fig. 9 and 10, the same components as those in the vehicle seat shown in Fig. 1 are designated by the same reference numerals, and their description will be omitted.

[0086] Regarding the contact portion described above, as shown in FIG. 9, a cutout portion 205A formed of a material having higher rigidity than the seat cushion 204, such as a resin material or a steel material, may be contacted to the front end of the seat cushion 204 so as to support the vicinity of the rear end portion 107 of the underside 109 of the leg rest portion 106.

[0087] Alternatively, as shown in FIG. 10 , the rear end 107 of the underside 109 of the leg rest portion 106 may be supported near the front end 205 of the seat cushion 204 of the rear seat 200. Supporting the rear end 107 of the leg rest portion 106 at the front end of the seat cushion 204 of the rear seat 200 using any of the above-described methods can increase the rigidity of the leg rest portion 106 when in use. Additionally, since the leg rest portion 106 does not need to be made as rigid, the leg rest portion 106 can be made thinner. This minimizes the space of the recess 103, allowing the front seat 100 to be made thinner. Furthermore, when a rear passenger P2 places their knees LL on the leg rest portion 106, the moment generated around the pivot shaft 110 causes the seat back 102 of the front seat 100 to deform rearward, preventing the front passenger P1 from feeling uncomfortable.

[0088] In all of the cases described with reference to Figures 8 to 10, when the legrest portion 106 is in use, the area near the center of the support surface 105 along the fore-and-aft direction of the seat is located at a higher position than the front end portion 205 of the seating surface 206 of the rear seat 200.

[0089] 9, the angular positional relationship between the inclination of the support surface 105 of the leg rest portion 106 and the seating surface 206 of the rear seat 200 will be described. As described above, when the leg rest portion 106 is in use, the support surface 105 provided on the upper surface portion of the leg rest portion 106 is located at the highest position of the support surface 105 on the rear end portion 107 side of the leg rest portion 106. At this time, the support surface 105 is inclined so as to rise toward the rear of the seat, with the horizontal plane as the reference. The inclination of the support surface 105 at this time is referred to as the support surface inclination angle θa, as shown in FIG.

[0090] The cyber angle adjustment mechanism 240 allows the seating surface 206 to be tilted downward from the horizontal plane toward the rear of the seat. The tilt angle of the seating surface 206 at this time is designated as seating surface tilt angle θb, as shown in FIG. 9 . In this embodiment of the present invention, the cyber angle adjustment mechanism 240 is configured to allow the seating surface tilt angle θb to be set larger than the support surface tilt angle θa. By setting the angle in this manner, the rear passenger P2 seated on the rear seat 200 can achieve a more relaxed seating posture.

[0091] Another example in which the support surface 105 provided on the upper surface of the leg rest 106 is positioned at the highest position of the support surface 105 on the rear end 107 side of the leg rest 106 when the leg rest 106 is in use will be described with reference to Fig. 9. It is also possible to provide a protrusion 112 on the rear end 107 side of the support surface 105. For example, even when the support surface inclination angle θa is close to 0°, by providing the protrusion 112 on the rear end 107 side of the support surface 105, it is possible to support the back of the knees of the rear-side passenger P2 seated on the rear seat 200, thereby maintaining the comfort of the rear-side passenger P2.

[0092] Fig. 11 is a side view showing a modified example of the vehicle seat according to the embodiment of the present invention. In Fig. 11, the same components as those in the vehicle seat shown in Fig. 8 are designated by the same reference numerals, and the description thereof will be omitted.

[0093] In the vehicle seat shown in Fig. 11, the cyber angle described with reference to Fig. 9 is set to a nearly horizontal position, and the height of the seat cushion 204 is set higher by the seat height adjustment mechanism 230. This allows a rear passenger P2, even if he or she is a small person, to have a clear view forward of the vehicle, which contributes to reducing motion sickness. When the embodiment shown in Fig. 11 is applied to a three-row one-box car or minivan-type automobile, the first seat 100 and the second seat 200 can also be used as a middle seat and a third seat, respectively.

[0094] Fig. 12 is a side view showing another modified example of the vehicle seat according to the embodiment of the present invention. In Fig. 12, the same components as those in the vehicle seat shown in Fig. 8 are designated by the same reference numerals, and the description thereof will be omitted.

[0095] In the vehicle seat shown in Figure 12, a leg rest flap 114 is attached to the rear end 107 of a leg rest portion 106 so as to be rotatable about a pivot shaft 116. When the leg rest flap 114 is not in use, it can be folded into a recess formed near the rear end 107 of the leg rest portion 106. When the distance (seat pitch) between the front seat 100 and the rear seat 200 is wide enough that the leg rest portion 106 does not come into contact with the seat cushion 204 of the rear seat 200, and when a rear passenger P2 seated on the rear seat 200 is small in size and the knees LL of the rear passenger P2 do not reach the leg rest portion 106, the leg rest flap 114 can be unfolded to allow the rear passenger P2 to place their feet on it.

[0096] When the embodiment shown in FIG. 12 is applied to a three-row seat minivan or minivan type automobile, the first seat 100 and the second seat 200 can be made into a middle seat and a third seat, respectively.

[0097] Fig. 13 is a side view showing yet another modified example of the vehicle seat according to the embodiment of the present invention. In Fig. 13, the same components as those of the vehicle seat shown in Fig. 8 are designated by the same reference numerals, and the description thereof will be omitted.

[0098] In the vehicle seat shown in FIG. 13 , an extension support mechanism 117 is pivotally supported on the rear side of the seat back 102 of the front seat 100 so as to be rotatable about a pivot shaft 110. A support portion 119 is provided on the side opposite to the pivotally supported side of the extension support mechanism 117. The legrest portion 106 is attached to the support portion 119 so as to be slidable along the extension direction of the extension support mechanism 117 relative to the extension support mechanism 117. When the distance (seat pitch) between the front seat 100 and the rear seat 200 is wide enough that the legrest portion 106 does not come into contact with the seat cushion 204 of the rear seat 200, and when the physique of a rear passenger P2 seated on the rear seat 200 is small enough that the knees LL of the rear passenger P2 do not reach the legrest portion 106, the legrest portion 106 can be raised from the recess 103 and then pulled out toward the rear seat 200. By pulling out the leg rest portion 106 toward the rear seat 200 as described above, it becomes possible for the knee region LL of the rear passenger P2 to rest on the leg rest portion 106. Even when the leg rest portion 106 is pulled out in this manner, it is desirable that the rear end 107 of the leg rest portion 106 and the front end portion 205 of the seat cushion 204 can abut against each other.

[0099] When the embodiment shown in FIG. 13 is applied to a three-row seat minivan or minivan type automobile, the first seat 100 and the second seat 200 can be made into a middle seat and a third seat, respectively.

[0100] FIG. 14 is a side view showing yet another modified example of the vehicle seat according to the embodiment of the present invention, illustrating a usage mode in which the leg rest portion 106 is used as a seating portion. In FIG. 14, the same components as those of the vehicle seat shown in FIG. 8 are designated by the same reference numerals, and their description will be omitted. FIG. 14 shows an example in which the vehicle seat includes a third seat 300 in addition to the front seat 100 and the rear seat 200. Like the rear seat 200, the third seat 300 includes a seat height adjustment mechanism 330, a seat cushion 304, a seat back 302, and an armrest 320. Note that the third seat 300 is not necessarily required for this embodiment and may be omitted.

[0101] The usage mode shown in Figure 14 is intended for use when, for example, a passenger P is relaxing or working in the vehicle while out and about. Passenger P can lift the leg rest 106 of the front seat 100 from the recess 103 of the seat back 102 and sit on the support surface 105. At this time, by adjusting the height of the seat cushion 204 using the seat height adjustment mechanism 230, the seat cushion 204 can be used as an ottoman. Even in this case, when the leg rest 106 is in use, the region of the support surface 105 near the center along the seat front-rear direction is positioned higher than the front end 205 of the seating surface 206 of the rear seat 200. Alternatively, the seat pitch between the front seat 100 and the rear seat 200 may be shortened so that the rear end 107 of the leg rest 106 abuts against the front end 205 of the seat cushion 204.

[0102] Fig. 15 is a side view showing yet another modified example of the vehicle seat according to the embodiment of the present invention, and is a diagram illustrating a usage mode in which the leg rest portion 106 is used as a seating portion, similar to that described with reference to Fig. 14. In Fig. 15, the same components as those of the vehicle seat shown in Figs. 8 and 14 are given the same reference numerals, and their description will be omitted. As in Fig. 14, Fig. 15 also shows an example in which the vehicle seat includes a third seat 300 in addition to the front seat 100 and the rear seat 200, but this third seat 300 is not necessarily required in this embodiment and may be omitted.

[0103] The following will focus on the differences between the vehicle seat shown in Figure 14 and the vehicle seat shown in Figure 15. While the leg rest 106 of the front seat 100 is used as a seating area, like the one shown in Figure 14, the one shown in Figure 15 differs in that the seat cushion 204 of the rear seat 200 is used as a table or storage stand rather than as an ottoman. The seat height adjustment mechanism 230A is configured to have a larger lifting stroke than the seat height adjustment mechanism 230 shown in Figures 8 to 14. For example, the seat height adjustment mechanism 230 could be configured as a multi-joint link mechanism, such as a four-joint parallel link mechanism stacked in multiple stages, or a scissor lift mechanism, etc.

[0104] 15 shows the state in which the air cells 108 built into the leg rest section 106 are inflated. By adjusting the degree of inflation of the air cells 108, it is possible to improve the comfort of sitting when using the leg rest section 106 as a seat.

[0105] The armrest 220 may be detachably attached to the side of the seat back 202. For example, the armrest 220 may be fixed to the pivot shaft 224 by a screw fastening method, or both the pivot shaft 224 and the armrest 220 may be provided with a structure that allows for bayonet connection. Alternatively, the end of the pivot shaft 224 may be a polygonal shaft shape or a D-cut shape obtained by cutting a portion of a round shaft into a flat shape, and the armrest 220 may be provided with a hole of a shape complementary to the shape of the shaft so that it can be fitted. By making the armrest 220 detachable, it is possible to attach any of several types of armrests that are prepared in advance. For example, when the seat cushion 204 is set high as shown in FIG. 15, attaching a large armrest 220A can prevent items placed on the seat cushion 204 from becoming unstable.

[0106] Fig. 16 is a side view showing yet another modified example of the vehicle seat according to the embodiment of the present invention, and is a diagram illustrating a usage mode in which the leg rest portion 106 is used as a seating portion, similar to the description with reference to Figs. 14 and 15. In Fig. 16, the same components as those of the vehicle seat shown in Figs. 8, 14, and 15 are designated by the same reference numerals, and their description will be omitted. As with Figs. 14 and 15, Fig. 16 also shows an example in which the vehicle seat includes a third seat 300 in addition to the front seat 100 and the rear seat 200, but this third seat 300 is not necessarily required for this embodiment and may be omitted.

[0107] In the example shown in Figure 16, the seat cushion 204 is configured to be tiltable downward toward the front of the vehicle using the cyber angle adjustment mechanism 240, and is also configured to be movable in the fore-and-aft direction. In the example shown, the seat cushion 204 is moved toward the front of the vehicle, i.e., toward the passenger P seated on the footrest 106. Furthermore, an armrest 220B equipped with an illumination device such as a reading lamp can be attached as needed. With this configuration, the seat cushion 204 can be used as a table in the mode in which the footrest 106 is used as a seat, and by using the armrest 220B equipped with an illumination device, it becomes possible to read or operate electronic devices such as a personal computer comfortably even in a dark environment.

[0108] 17 is a diagram showing an example in which the ottoman device, i.e., the leg rest portion 106, can be interchanged between a plurality of different seats. In FIG. 17, the same components as those shown in FIG. 8 are designated by the same reference numerals and their description will be omitted.

[0109] A rotating shaft 101, which extends in the width direction of the vehicle and to which a footrest 106A can be detachably attached, is provided near the front end of the seat cushion 104 of the front seat 100. The footrest 106A attached to the rotating shaft 101 is configured so that the angle of inclination in the fore-and-aft direction of the vehicle relative to the horizontal plane can be adjusted.

[0110] A leg rest 106B is detachably attached to the rear side of the seat back 102 of the front seat 100. Similarly, a leg rest 106C is detachably attached to the rear side of the seat back 202 of the rear seat 200. The above-mentioned leg rests 106A, 106B, and 106C are all compatible in shape, and any of these three, or any other leg rest not shown in FIG. 17, can be attached to any of the above-mentioned locations according to the user's preference.

[0111] The above-described leg rests 106A, 106B, and 106C, as well as other leg rests not shown in FIG. 17 , can incorporate various functions. For example, the leg rest 106A can incorporate a heater or ventilation function in addition to the air cell 108. The leg rest 106B can incorporate a sensor in addition to the air cell 108. Examples of sensors that can be incorporated include a seating sensor, a pressure sensor, and a biosensor. The leg rest 106C can incorporate a speaker or an occupant protection device, such as an airbag, in addition to the air cell and sensor. Alternatively, a vibration generator can be incorporated instead of the air cell, providing a massage function. The above-described functions are merely examples, and any desired function can be incorporated individually or in combination. Users can attach leg rests with their preferred functions to their preferred seats. Alternatively, the leg rests may not incorporate any functions, or the material and color of the leg rest's surface can be changed to allow users to coordinate the vehicle's interior to their preferences. By making each leg rest detachable, it is possible to improve the workability when cleaning.

[0112] The following advantageous effects can be achieved according to the embodiment of the present invention. (1) A vehicle seat includes a first seat 100 and a second seat 200 disposed behind the first seat 100. The first seat 100 includes a first seat cushion 104 and a first seat back 102 extending from the rear end of the first seat cushion 104. The second seat 200 includes a second seat cushion 204 and a second seat back 202 extending from the rear end of the second seat cushion 204. The first seat back 102 includes a leg rest 106 having a support surface 105 that protrudes rearward in an in-use state and supports a knee region LL of a rear passenger P2 seated in the second seat 200. The vehicle seat further includes a support portion that supports the leg rest 106 so that the leg rest 106 is positioned above a front end 205 of the seating surface 206 of the second seat cushion 204 in an in-use state shown in FIG. The support portion may be provided with a stopper on the pivot shaft 110 so that when the leg rest portion 106 is pulled out to the angle position for use, it stops at that angle position. Alternatively, as shown in Figures 9 and 10, the leg rest portion 106 may be supported near the front end of the seat cushion 204. With the vehicle seat described above, the support surface that supports the leg rest portion and the front end of the second seat cushion are close to each other, so that the legs of the seated occupant can be stably supported and the occupant can be kept relaxed for a long time.

[0113] (2) In the vehicle seat described above, when the leg rest portion 106 is in use, the second seat cushion 204 comes into contact with the leg rest portion 106. This allows the second seat cushion 204 and the leg rest portion 106 in contact therewith to secure a continuous support surface for supporting the lower knee portions LL.

[0114] (3) In the vehicle seat described above, when the leg rest portion 106 is in use, the rear end portion 107 of the leg rest portion 106 abuts against the front end portion 205 of the seating surface 206 of the second seat cushion 204. This reduces the area where the leg rest portion 106 and the second seat cushion 204 overlap in the vertical direction, making it easier to ensure the length of the surface supporting the knee-lower portions LL in the front-rear direction. Furthermore, the support surface 105 for supporting the knee-lower portions LL can be made smoother and more continuous.

[0115] (4) In the vehicle seat described above, when the leg rest portion 106 is in use, the underside 109 of the rear end portion 107 of the leg rest portion 106 is supported by the second seat cushion 204. This allows the rear end portion 107 of the leg rest portion 106 to be supported by the second seat cushion 204, thereby reducing the rigidity required for the leg rest portion 106. This makes it possible to reduce the thickness of the leg rest portion 106 and prevent the first seat back 102 from becoming larger.

[0116] (5) When the leg rest 106 of the vehicle seat is in use, the region of the support surface 105 near the center along the front-rear direction of the seat is located higher than the front end 205 of the seating surface 206 of the second seat cushion 204. This allows the position of the lower-knee area LL to be higher, making it possible to prevent blood from accumulating in the lower-knee area LL.

[0117] (6) In the vehicle seat described above, the support portion preferably supports the leg rest portion 106 such that, in use, the rear end of the leg rest portion 106 is at the highest position on the support surface 105. By making the rear end of the leg rest portion 106 the highest on the support surface in this way, the area below the knees is more easily supported, improving comfort.

[0118] (7) In the vehicle seat described above, the second seat cushion 204 is configured to be rotatable about an axis 242 extending in the seat width direction, and further includes a cyber angle adjustment mechanism 240 that can adjust the tilt angle of the second seat cushion 204 in the seat front-to-rear direction, and is configured to be able to set a tilt angle θb at which the second seat cushion 204 decreases toward the rear of the seat that is greater than a tilt angle θa at which the support surface 105 increases toward the rear of the seat, with respect to the horizontal plane, when the leg rest portion 106 is in use. This allows the seat occupant to achieve a more relaxed sitting posture.

[0119] (8) The vehicle seat further includes a second seat height adjustment mechanism 230A that can adjust the height of the second seat cushion 204, and the second seat height adjustment mechanism 230A is configured to be able to set the height of the second seat cushion 204 higher than the support surface 105 when the leg rest portion 106 is in use, in a mode in which the leg rest portion 106 is used as a seating portion. This allows the second seat cushion 204 to be used as a table or storage space, increasing convenience.

[0120] (9) In the vehicle seat described above, the second seat back 202 is provided with an armrest mounting portion to which one of the armrests 220, 220A, which are available in multiple types, can be detachably mounted. This makes it possible to mount the armrest 220 or 220A that is appropriate for the set height of the second seat cushion.

[0121] (10) In the vehicle seat described above, when the height of the second seat cushion 204 is set higher than the support surface 105 when the leg rest portion 106 is in the use state, an armrest 220A having a shape that can prevent a passenger seated on the second seat 200 or an object placed thereon from becoming unstable can be attached. In this way, the armrest can be used to stabilize the object.

[0122] (11) In the vehicle seat described above, the upper surface 226 of the armrest 220 has a forearm support surface 226 that supports the forearms of a passenger seated in the second seat, and an operating unit 222 that is provided on the forearm support surface 226 and can be operated by the passenger, and the armrest 220 is configured so that the angle of the forearm support surface 226 can be set so that it is inclined downward toward the front in the fore-and-aft direction of the seat, and can be rotated to a storage position in a direction that further increases the angle of the downward inclination toward the front. By doing so, even when the armrest is rotated to the storage position, the operating unit can be easily reached, thereby improving operability.

[0123] The configuration of the vehicle seat described with reference to Figures 8 to 17 can be summarized as follows. The vehicle seat includes a first seat and a second seat disposed behind the first seat. The first seat includes a first seat cushion and a first seat back extending from the rear end of the first seat cushion. The second seat includes a second seat cushion and a second seat back extending from the rear end of the second seat cushion. The first seat back includes a leg rest portion having a support surface that protrudes rearward in an in-use state and supports the lower knees of a passenger seated in the second seat. The vehicle seat further includes a support portion that supports the leg rest portion so that the leg rest portion is positioned above the front end of the seating surface of the second seat cushion in an in-use state. In the in-use state described above, the second seat cushion and the leg rest portion abut against each other. In the in-use state described above, the rear end of the leg rest portion abuts against the front end of the seating surface of the second seat cushion. Alternatively, in the in-use state described above, the underside of the rear end of the leg rest portion is supported by the second seat cushion. In the above-described use state, a region near the center of the support surface in the seat's fore-and-aft direction is positioned higher than the front end of the seating surface of the second seat cushion. The above-described support portion supports the leg rest portion so that the rear end of the leg rest portion is at the highest position on the support surface in the use state. The above-described second seat cushion is configured to be rotatable about an axis extending in the seat width direction and further includes a cyber angle adjustment mechanism capable of adjusting the inclination angle of the second seat cushion in the seat's fore-and-aft direction. The vehicle seat is configured to be able to set, in the use state, an inclination angle at which the second seat cushion decreases toward the rear of the seat, relative to the horizontal plane, greater than an inclination angle at which the support surface increases toward the rear of the seat. The vehicle seat further includes a second seat height adjustment mechanism capable of adjusting the height of the second seat cushion. The second seat height adjustment mechanism is configured to set the height of the second seat cushion higher than the support surface in the use state in a mode in which the leg rest portion is used as a seating portion. The vehicle seat is provided with an armrest attachment portion on the above-described second seat back to which one of several types of armrests can be detachably attached.The vehicle seat is configured to be able to mount an armrest having a shape that can prevent a passenger or an object placed on the second seat from becoming unstable when the height of the second seat cushion is set higher than the support surface in the in-use state. The upper surface of the armrest has a forearm support surface that supports the forearms of a passenger seated on the second seat, and an operating unit that is provided on the forearm support surface and can be operated by the passenger. The armrest is configured so that the angle of the forearm support surface can be set so that it is inclined downward toward the front in the fore-and-aft direction of the seat.

[0124] In the above embodiment, the seat is incorporated into a vehicle as a vehicle seat, but the seat may be used as a seat for vehicles other than a vehicle, for example, a seat for an aircraft or the like.

[0125] The above description is merely an example, and the present invention is not limited to the above-described embodiment and modifications as long as the features of the present invention are not impaired. One or more of the above-described embodiment and modifications can be arbitrarily combined, and modifications can also be combined with each other.

[0126] REFERENCE SIGNS LIST 1 seat, 1a seat cushion, 1b seat back, 1c headrest, 2 vehicle, 3 surface pressure sensor, 4 operation pedal, 5 controller, 5a fatigue evaluation unit, 10 fatigue evaluation device, 100 front seat, 102 seat back, 103 recess, 104 seat cushion, 105 support surface, 106 foot rest, 107 rear end, 108 air cell, 109 underside, 110 pivot shaft, 112 protrusion, 120 armrest, 122 operation unit, 130 seat height adjustment mechanism, 200 rear seat, 202 seat back, 204 seat cushion, 205 front end, 205A cutout portion, 206 seating surface, 220 armrest, 222 operation unit, 224 pivot shaft, 226 upper surface, 230 seat height adjustment mechanism, 230A Seat height adjustment mechanism, 240 Cyber ​​angle adjustment mechanism, 242 Rotation axis, LL Lower part of knee, P1 Front passenger, P2 Rear passenger

Claims

1. A fatigue assessment device comprising: a sensor that detects the movement of any of the right leg, left leg, right arm, left arm, or neck of a person seated in a seat; and a fatigue assessment unit that assesses the fatigue state of the person based on the detection results of the sensor.

2. A fatigue assessment device according to claim 1, wherein the seat is mounted on a vehicle in which the occupant operates the vehicle using one of the right leg and the left leg, and the sensor detects the movement of the other of the right leg and the left leg.

3. A fatigue assessment device as described in claim 1, characterized in that the sensor detects the movement of the right leg and the movement of the left leg, and the fatigue assessment unit assesses the fatigue state based on the greater of the movement of the right leg and the movement of the left leg detected by the sensor.

4. A fatigue assessment device according to any one of claims 1 to 3, characterized in that the fatigue assessment unit calculates the amount of variation in the center of gravity position in at least one of the front-to-rear and width directions of the seat based on the detection results from the sensor, and assesses the fatigue state based on the calculated amount of variation.

5. A fatigue assessment device according to claim 4, wherein the center of gravity position is a coordinate value in at least one of the front-rear direction and the width direction.

6. A fatigue assessment device according to any one of claims 1 to 3, wherein the sensor is a pressure sensor provided on the seating surface of the seat that contacts any of the right leg, the left leg, the right arm, the left arm, and the neck, and the fatigue assessment unit assesses the fatigue state based on the detection results of the sensor in an area of ​​the seating surface that is distant from the torso of the occupant.

7. A fatigue assessment device according to claim 2, wherein the sensor is a pressure sensor and is provided on the other side of the center of the seat surface of the seat and in a range away from the buttocks of the seated person.

8. A fatigue assessment device as described in claim 5, wherein the fatigue assessment unit calculates the amount of fluctuation at a predetermined cycle, calculates an evaluation value by performing a smoothing process on the calculated amount of fluctuation, and evaluates the fatigue state based on the calculated evaluation value, and the smoothing process calculates the current evaluation value as the sum of the current amount of fluctuation and the previous evaluation value multiplied by a predetermined weighting coefficient.

9. A fatigue assessment device according to claim 8, wherein the fatigue assessment unit performs a normalization process to normalize the current evaluation value to a value between 0 and 1 based on the ranking of the current evaluation value in a predetermined data group, and assesses the fatigue state based on the current evaluation value normalized by the normalization process.

10. A fatigue assessment device according to claim 9, wherein the predetermined data group is all of the assessment values ​​calculated for the same seated occupant.

11. A fatigue assessment device according to any one of claims 1 to 3, characterized in that the fatigue assessment unit assesses the fatigue state using a logistic regression model in which whether the seated occupant is fatigued is used as a dependent variable and a value calculated based on the detection results by the sensor is used as an explanatory variable.

12. A fatigue assessment device according to claim 1, wherein the sensor detects the movement of the left leg.

13. A vehicle equipped with the fatigue assessment device according to any one of claims 1 to 3.

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