Kicking sensor

Abstract

Provided is a kicking sensor capable of preventing erroneous detection. A kicking sensor (1), which is provided in a vehicle and detects a motion of a person's leg that is a trigger of control of a door of the vehicle, is provided with: a first antenna (10) that receives radio waves from at least a side of the door of the vehicle; and a second antenna (20) that receives radio waves from at least below the door of the vehicle.

Description

Technical Field

[0001] This invention relates to a kicking sensor installed in a vehicle and detecting the movement of a person's leg that triggers the control of the vehicle's doors. Background Art

[0002] Conventionally, door opening and closing devices have been used that automatically lock or unlock vehicle doors and open and close vehicle doors. For example, such a door opening and closing device is described in Patent Document 1, which is cited below.

[0003] Patent Document 1 describes a vehicle door opening and closing device that includes a non-contact detection unit for detecting the presence of a user near a vehicle door and for setting the door to an open state after it has been unlocked from a locked state. This detection unit includes a detection sensor installed near the door and for detecting objects located below the door.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2019-116824

[0005] The door opening and closing device described in Patent Document 1 is configured such that a detection sensor detects an object located below the door. Therefore, even if the detection sensor detects a person (leg) such as a cat, who does not intend to open the door, there is a possibility that the door may be mistakenly opened.

[0006] Therefore, efforts are being made to develop kick sensors that can prevent false detections. Summary of the Invention

[0007] The kicking sensor of the present invention is characterized by the following aspect: it is a kicking sensor installed in a vehicle and detecting the movement of a person's leg triggered by the control of the vehicle's door, comprising: a first antenna that receives radio waves from at least the side of the vehicle's door; and a second antenna that receives radio waves from at least the bottom of the vehicle's door.

[0008] Based on this characteristic structure, by using the reception of side-borne radio waves by the first antenna and the reception of downward-borne radio waves by the second antenna as conditions, the state of the vehicle door can be switched from one of the open and closed states, or the door lock can be switched from one of the locked and unlocked states. Therefore, compared to using either the reception of side-borne or downward-borne radio waves as conditions to switch the state of the vehicle door from one of the open and closed states, or the door lock from one of the locked and unlocked states, false detections can be prevented, for example, when an animal passes near the kick sensor, or when a person passes by or moves without intending to switch the state of the vehicle door or door lock. Thus, based on the kick sensor, the state of the vehicle door or door lock can be appropriately switched by detecting the movement (activity) of a person's leg. Attached Figure Description

[0009] Figure 1 This is a diagram showing a vehicle equipped with a kick sensor.

[0010] Figure 2 This is a top view of the kick sensor.

[0011] Figure 3 This is a diagram showing the directional characteristics of the first datum.

[0012] Figure 4 This is a diagram illustrating the directional characteristics of the second antenna.

[0013] Figure 5 It is a diagram representing the input form of opening and closing commands based on human legs.

[0014] Figure 6 This is a top view of a kicking sensor in another embodiment.

[0015] Figure 7 This is a top view of a kicking sensor in another embodiment.

[0016] Figure 8 This is a top view of a kicking sensor in another embodiment.

[0017] Figure 9 This is a diagram representing the transition between the first and second states.

[0018] Explanation of reference numerals in the attached figures

[0019] 1: Kick sensor, 2: Vehicle, 3: Door, 4: Person, 4A: Leg, 5: Substrate, 5A: Surface, 10: First antenna, 20: Second antenna, 30: Control unit. Detailed Implementation

[0020] The kick sensor of the present invention can detect operation commands for switching the status of vehicle doors and door locks. Hereinafter, the kick sensor 1 of this embodiment will be described. However, the kick sensor 1 is not limited to the following embodiment, and various modifications can be made without departing from its spirit.

[0021] like Figure 1 As shown, a kick sensor 1 is installed in vehicle 2. As described above, the kick sensor 1 detects operation commands used to switch the state of the vehicle 2's door 3 and door lock. The vehicle 2's door 3 refers to a door installed in vehicle 2 that can be opened and closed by an actuator. Specifically, it could be, for example, a rear door 3A (tailgate) installed at the rear of vehicle 2, or a sliding door 3B installed on the side of vehicle 2. The door lock refers to a mechanism installed on the aforementioned door 3 that can switch between a locked state where the door 3 is not opened and an unlocked state where the door 3 can be opened. Hereinafter, the rear door 3A will be used as an example to describe the vehicle 2's door 3.

[0022] Switching the state of vehicle 2's door 3 and door lock refers to controlling vehicle 2's door 3. Specifically, it means switching vehicle 2's door 3 from an open state to a closed state, and setting vehicle 2's door 3 from a closed state to an open state. Furthermore, it means switching locked door locks from a locked state to an unlocked state, and switching unlocked door locks from a locked state to a locked state. The operation command is equivalent to a command input by person 4 that triggers such control of switching the state of vehicle 2's door 3 and door lock. This command is input through the movement of person 4's leg 4A.

[0023] Therefore, the kick sensor 1 is configured to detect a command triggered by the movement input of a person's leg 4A, which is used to switch the rear door 3A of the vehicle 2 from an open state to a closed state; and a command triggered by the movement input of a person's leg 4A, which is used to switch the rear door 3A of the vehicle 2 from a closed state to an open state. Furthermore, it is configured to detect a command triggered by the movement input of a person's leg 4A, which is used to switch the door lock from a locked state to an unlocked state; and a command triggered by the movement input of a person's leg 4A, which is used to switch the door lock from an unlocked state to a locked state.

[0024] Figure 2 A top view of the kicking sensor 1 is shown. (As shown) Figure 1 as well as Figure 2As shown, the kick sensor 1 includes a first antenna 10, a second antenna 20, and a control unit 30. The first antenna 10 receives radio waves from at least the side of the vehicle door 3 of the vehicle 2. The side of the vehicle door 3 refers to the direction along the horizontal direction centered on the vehicle door 3, and is not limited to both sides (left and right sides) in the width direction of the vehicle 2, including the rear of the vehicle 2. In this embodiment, the case where the side of the vehicle door 3 is the rear of the vehicle door 3A will be described. Therefore, in this embodiment, the first antenna 10 receives radio waves propagating in the air from the rear of the vehicle door 3A, as an example, from the side of the vehicle door 3.

[0025] In this embodiment, the first antenna 10 is configured as a patch antenna (microstrip antenna). The first antenna 10 is formed by a pattern formed on the substrate 5. The substrate 5 is composed of a multilayer printed circuit board (in this embodiment, a printed circuit board containing four conductor layers). If the four conductor layers are designated as a first conductor layer, a second conductor layer, a third conductor layer, and a fourth conductor layer, the substrate 5 is constructed by stacking the conductor layers from the bottom in the order of the first conductor layer, the second conductor layer, the third conductor layer, and the fourth conductor layer, with an insulating layer provided between the two stacked conductor layers. The first antenna 10 has a first antenna element 10A and a second antenna element 10B disposed on different conductor layers. The first antenna element 10A is formed on the fourth conductor layer, and the second antenna element 10B is formed on the third conductor layer. The first antenna element 10A and the second antenna element 10B are each configured to have a quadrilateral shape in the top view, and in the top view, the size (area) of the first antenna element 10A is larger than the size (area) of the second antenna element 10B. Furthermore, in Figure 2 Although the second antenna element 10B is shown in dashed lines, this is for ease of understanding. When viewing the substrate 5 from the side 5A, the second antenna element 10B is actually not visible.

[0026] Furthermore, the first antenna element 10A and the second antenna element 10B can transmit and receive radio waves at different frequencies. The first antenna element 10A and the second antenna element 10B are electrically connected to the first conductor layer via through-hole TH, respectively. On the side opposite to surface 5A of the substrate 5, a pad and grounding pattern extending from the through-hole TH are configured to mount a capacitor. The impedance can be adjusted according to the electrostatic capacitance value of the capacitor.

[0027] The conductor patterns of the first conductor layer and the conductor patterns of the second conductor layer have portions facing each other in the stacking direction, separated by an insulating layer disposed between the first and second conductor layers. Thus, unlike the capacitor described above, an electrostatic capacitor is formed by the conductor patterns of the first and second conductor layers and the insulating layer, respectively. The impedance can also be adjusted using this electrostatic capacitor.

[0028] The third conductor layer includes a third-layer pattern forming region for forming the second antenna element 10B, and a ground region configured to surround the third-layer pattern forming region. Furthermore, the first-layer pattern forming region for forming the conductor pattern of the first conductor layer includes an overlapping region that overlaps with the second antenna element 10B in a top view, and at least a portion of this overlapping region contains unformed areas where the first-layer pattern is not formed. Thus, the closure of the electric field lines between the first antenna element 10A and the second antenna element 10B is suppressed, enabling efficient transmission or incident of radio waves. Moreover, the overlapping region corresponds to the area directly below the second antenna element 10B.

[0029] The second antenna 20 receives radio waves from at least below the door 3 of vehicle 2. Below the door 3 of vehicle 2 refers to the road surface 200 where vehicle 2 is parked (see reference). Figure 5 Therefore, the second antenna 20 receives radio waves propagating into the air from the side of the road surface 200 where the vehicle 2 is parked.

[0030] In this embodiment, the second antenna 20 is configured as a Vivaldi antenna. The second antenna 20 also has a pattern formed on the substrate 5. In this embodiment, the first antenna 10 and the second antenna 20 are configured on a single substrate 5. The second antenna 20 has a first antenna element 21 for antenna matching (impedance matching) and a second antenna element 22 for receiving radio waves. Figure 2 In the top view, the first antenna element 21 is square, but it can also be circular or rectangular. Alternatively, it can be triangular or n-sided (n is an integer greater than 5). The second antenna element 22 extends from the first antenna element 21 toward a side of the substrate 5 opposite to the side where the first antenna element 21 is located. The width of the second antenna element 22 in a direction orthogonal to the direction extending toward the opposite side gradually increases with distance from the first antenna element 21. In this embodiment, this width increases exponentially. The first antenna element 21 and the second antenna element 22 are formed in the first conductor layer, and the conductor layers of the second, third, and fourth conductor layers that overlap with the first conductor layer are removed.

[0031] like Figure 1As shown, the substrate 5 is disposed on the rear end of the vehicle 2 with the surface 5A of the substrate 5 in which the first antenna 10 and the second antenna 20 are formed facing the rearward direction of the vehicle 2. Specifically, the substrate 5 is disposed on the rear bumper 1B of the vehicle 2 with the surface 5A of the substrate 5 in which the first antenna 10 and the second antenna 20 are formed facing the rear of the vehicle 2. When the rear bumper 1B is made of resin material, the substrate 5 may also be disposed inside the rear bumper 1B. Of course, the substrate 5 may also be disposed in a state that exposes from the rear bumper 1B.

[0032] exist Figure 3 The pointing characteristics of the first antenna 10 are shown in the diagram. The first antenna 10 has... Figure 3 The first antenna 10 exhibits a ring-shaped directional characteristic as shown. Furthermore, when the substrate 5 is viewed from a direction parallel to surface 5A, the first antenna 10 also displays a ring-shaped directional characteristic (not shown). Therefore, the first antenna 10 becomes directional relative to radio waves originating from the side (in this embodiment, the rear of the vehicle 2).

[0033] Furthermore, the first antenna 10 is configured to transmit radio waves to the rear of the vehicle 2, and to transmit and receive both vertically polarized and horizontally polarized radio waves. Thus, the first antenna 10 can not only detect the legs 4A of the person 4, but can also be used, for example, in communication with the vehicle 2 and a mobile terminal storing an electronic key.

[0034] exist Figure 4 The pointing characteristics of the second antenna 20 are shown. As described above, the second antenna 20 has a second antenna element 22. The second antenna 20 has Figure 4 As shown, it has strong directional characteristics relative to the direction in which the second antenna element 22 extends (in... Figure 4 In the middle, along the 270-degree direction), the directional accuracy is weak relative to the side opposite to the direction in which the second antenna element 22 extends (in Figure 4 The second antenna 20 exhibits a directional characteristic within the range of 0 to 180 degrees. Furthermore, the second antenna 20 has a significantly weaker directional characteristic in the direction orthogonal to the surface 5A on which it is located in the substrate 5 (not shown). Therefore, the second antenna 20 is configured to be directional relative to radio waves originating from below (in this embodiment, the road surface 200 side), and is capable of transmitting radio waves to the road surface 200 side, and of receiving and transmitting polarized radio waves oscillating parallel to the surface 5A.

[0035] Figure 5 This diagram illustrates the input pattern of an opening / closing command caused by the movement of the leg 4A of person 4. As described above, the kicking sensor 1 is located at the rear end of vehicle 2. The first antenna 10 receives radio waves from the rear of vehicle 2. Figure 5In the example, radio waves are received from the shin of the leg 4A of person 4. On the other hand, the second antenna 20 receives radio waves from the side of the road surface 200. Figure 5 In this example, radio waves are received from the toes of the leg 4A of person 4. Thus, the kick sensor 1 detects, through both the first antenna 10 and the second antenna 20, an opening / closing command that triggers a switch of the state of the vehicle door 3 of vehicle 2. The detection results from the first antenna 10 and the second antenna 20 are transmitted to the control unit 30. If both the first antenna 10 and the second antenna 20 receive radio waves within a specified time, the control unit 30 switches the state of the vehicle door 3 of vehicle 2 from one of the open state and the closed state to the other. Alternatively, it switches the door lock from one of the unlocked state and the locked state to the other.

[0036] Thus, according to this kick sensor 1, when both the first antenna 10 and the second antenna 20 detect radio waves, the state of the car door 3 and the door lock is changed. Therefore, compared with the structure that switches the state of the car door 3 and the door lock when one of the first antenna 10 and the second antenna 20 detects radio waves, the change of the state of the car door 3 and the door lock caused by false detection can be reduced.

[0037] In the kick sensor 1, the first antenna 10 and the second antenna 20 each emit radio waves at predetermined intervals, and then enter a state capable of receiving the reflected radio waves. The switching between the emitted and received radio wave states of the first antenna 10 and the second antenna 20 is performed by the control unit 30. Specifically, the first antenna 10 emits radio waves toward the rear of the vehicle 2 at predetermined intervals, and during the period from the end of one emitted radio wave to the beginning of the next, it is in a receiving state capable of receiving radio waves. Similarly, the second antenna 20 emits radio waves toward the road surface 200 at predetermined intervals, and during the period from the end of one emitted radio wave to the beginning of the next, it is in a receiving state capable of receiving radio waves.

[0038] As described above, based on kick sensor 1, such as Figure 1 As shown, even when a person 4 using vehicle 2 is holding goods with both hands, the movement (activity) of the person 4's legs 4A related to the opening and closing commands issued by the person 4 through the legs 4A can be detected, and the state of the vehicle 2's doors 3 and door locks can be switched appropriately.

[0039] [Other Implementation Methods]

[0040] Next, other embodiments of the kicking sensor 1 will be described.

[0041] In the above embodiment, the second antenna 20 is described as having a first antenna element 21 and a second antenna element 22, wherein the second antenna element 22 is configured to expand exponentially with respect to the first antenna element 21. However, as Figure 6 As shown, the second antenna element 22 of the second antenna 20 can also be configured to extend linearly as it moves away from the first antenna element 21.

[0042] In the above embodiment, it was described that the first antenna 10 is a patch antenna. However, as... Figure 7 As shown, the first antenna 10 can also be constructed from a Vivaldi antenna. Or, as... Figure 8 As shown, it can also be configured such that the element part protrudes from the ground pattern.

[0043] In the above embodiment, it is described that the first antenna 10 and the second antenna 20 radiate radio waves at predetermined time intervals, and then are configured to receive the reflected radio waves after the radiated radio waves are received. For example, the control unit 30 may also be configured to alternately switch the states of the first antenna 10 and the second antenna 20 between a first state in which one of the first antenna 10 and the second antenna 20 transmits radio waves and a second state in which the other of the first antenna 10 and the second antenna 20 transmits radio waves.

[0044] like Figure 9 As shown, in the first state, the first antenna 10 transmits radio waves to the side and below the vehicle 2 (#11), receives radio waves from the shin of the leg 4A of the person 4 corresponding to the transmitted radio waves (#12), and the second antenna 20 receives radio waves from the toes of the leg 4A (#13). On the other hand, in the second state, the second antenna 20 transmits radio waves to the below of the vehicle 2 (#21), and the first antenna 10 and the second antenna 20 receive radio waves from the toes of the leg 4A of the person 4 corresponding to the transmitted radio waves (#22). In this case, since no radio waves are transmitted from the second antenna 20 to the side of the vehicle 2, it is difficult to receive radio waves from the side of the vehicle 2.

[0045] In a first state, for example, the first antenna 10 transmits radio waves in predetermined time intervals, and during the period from receiving the radio wave to the next transmission, the control unit 30 sets both the first antenna 10 and the second antenna 20 to a receiving state. Alternatively, in a second state, the control unit 30 sets both the first antenna 10 and the second antenna 20 to a receiving state during the period from receiving the radio wave to the next transmission. With this configuration, compared to transmitting and receiving radio waves individually in both the first antenna 10 and the second antenna 20, the number of transmissions can be reduced, thus reducing power consumption.

[0046] Furthermore, in this case, the control unit 30 can also be configured to determine whether a person 4's leg 4A has moved based on the ratio of the intensity of the radio wave received by the first antenna 10 to the intensity of the radio wave received by the second antenna 20. For example, if the ratio of the intensity of the radio wave received by the first antenna 10 to the intensity of the radio wave received by the second antenna 20 is within a predetermined value, and both the intensity of the radio wave received by the first antenna 10 and the intensity of the radio wave received by the second antenna 20 are stronger than the predetermined value, it can be determined that a person 4's leg 4A, with the intention of switching the state of the vehicle 2's door 3 and door lock, has moved to the side and below the door 3. Therefore, false detection can be prevented.

[0047] [Summary of the above embodiments]

[0048] The following is a summary of the kicking sensor 1 described above.

[0049] (1) The kicking sensor 1 is installed in the vehicle 2 and detects the movement of the leg 4A of the person 4 triggered by the control of the door 3 of the vehicle 2. It has a first antenna 10 for receiving radio waves from at least the side of the door 3 of the vehicle 2 and a second antenna 20 for receiving radio waves from at least the bottom of the door 3 of the vehicle 2.

[0050] According to this structure, by using the reception of side-facing radio waves by the first antenna 10 and the reception of downward-facing radio waves by the second antenna 20 as conditions, the state of the vehicle 2's door 3 can be switched from one of the open and closed states, or the door lock can be switched from one of the locked and unlocked states. Therefore, compared to using either the reception of side-facing radio waves or the reception of downward-facing radio waves as conditions to switch the state of the vehicle 2's door 3 from one of the open and closed states, or the door lock from one of the locked and unlocked states, false detections can be prevented, for example, when an animal passes near the kicking sensor 1, or when a person passes by or moves without intending to switch the state of the vehicle 2's door 3 or door lock. Thus, based on the kicking sensor 1, the movement (activity) of a person 4's leg 4A can be detected, and the state of the vehicle 2's door 3 or door lock can be switched appropriately.

[0051] (2) In the kicking sensor 1 described in (1), the first antenna 10 is preferably directional relative to radio waves from the side.

[0052] According to this structure, radio waves from the side can be appropriately received via the first antenna 10. Therefore, the kicking sensor 1 can appropriately detect the shin of the leg 4A of the person 4.

[0053] (3) In the kicking sensor 1 described in (1) or (2), the second antenna 20 is preferably directional relative to the radio waves coming from below.

[0054] According to this structure, radio waves from below can be appropriately received via the second antenna 20. Therefore, the kicking sensor 1 can appropriately detect the toes of the leg 4A of the person 4.

[0055] (4) In the kicking sensor 1 described in (1) to (3), the first antenna 10 and the second antenna 20 are preferably composed of a pattern formed on a single substrate 5.

[0056] According to this structure, in the case where the substrate 5 is made of a printed circuit board, the kicking sensor 1 can be cheaply constructed by forming the first antenna 10 and the second antenna 20 on a single printed circuit board.

[0057] (5) In the kicking sensor 1 described in (4), preferably the substrate 5 is provided on the rear end side of the vehicle 2 with the surface 5A on which the first antenna 10 and the second antenna 20 are formed facing the rear side of the vehicle 2 in the direction of travel.

[0058] According to this structure, the kick sensor 1 can be used in the opening and closing control of the rear door 3A (rear luggage door) of the vehicle 2. Therefore, the shin of the leg 4A extending from the rear side of the vehicle 2 toward the kick sensor 1 can be detected by the first antenna 10, and the toes of the leg 4A protruding downward from the rear side of the vehicle 2 can be detected by the second antenna 20.

[0059] (6) In the kicking sensor 1 described in (1) to (5), the first antenna 10 is preferably capable of transmitting and receiving radio waves of vertically polarized waves and radio waves of horizontally polarized waves.

[0060] For example, when locking and unlocking the locking mechanism of vehicle 2 using a mobile terminal and an electronic key, the radio waves from the mobile terminal are mostly horizontally polarized waves. Therefore, the first antenna 10 is configured to transmit and receive both vertically polarized and horizontally polarized radio waves, thus enabling it not only to switch the state of the vehicle door 3 from open to closed, but also to communicate with the mobile terminal.

[0061] (7) In the kicking sensor 1 described in (1) to (6), it is preferable that the first antenna 10 can transmit radio waves to the side and the second antenna 20 can transmit radio waves downward.

[0062] According to this structure, the first antenna 10 and the second antenna 20 can also be used in the transmission of radio waves for detecting human 4. Therefore, the transceiver antenna can be constructed in a low-cost and compact manner.

[0063] (8) In the kicking sensor 1 described in (1) to (7), it is preferable to further include a control unit 30, which alternately switches the state of the first antenna 10 and the second antenna 20 to a first state in which one of the first antenna 10 and the second antenna 20 transmits radio waves, and a second state in which the other of the first antenna 10 and the second antenna 20 transmits radio waves.

[0064] According to this structure, in a first state, for example, the first antenna 10 can transmit radio waves in predetermined time intervals, and during the period from the transmission of the radio wave to the next transmission, both the first antenna 10 and the second antenna 20 can be set to a receiving state. Furthermore, in a second state, the second antenna 20 can transmit radio waves in predetermined time intervals, and during the period from the transmission of the radio wave to the next transmission, both the first antenna 10 and the second antenna 20 can be set to a receiving state. With this structure, compared to the case where radio waves are transmitted and received individually in both the first antenna 10 and the second antenna 20, the number of radio wave transmissions can be reduced, thus reducing power consumption.

[0065] (9) In the kicking sensor 1 described in (8), it is preferable to determine whether the person 4’s leg 4A has been moved based on the ratio of the intensity of the radio wave received by the first antenna 10 to the intensity of the radio wave received by the second antenna 20.

[0066] According to this structure, for example, if the ratio of the intensity of the radio wave received by the first antenna 10 to the intensity of the radio wave received by the second antenna 20 (intensity of the radio wave received by the first antenna 10 / intensity of the radio wave received by the second antenna 20) is greater than a predetermined value, it can be determined that there is activity on the side of the door 3; if the ratio of the intensity of the radio wave received by the first antenna 10 to the intensity of the radio wave received by the second antenna 20 (intensity of the radio wave received by the first antenna 10 / intensity of the radio wave received by the second antenna 20) is less than the predetermined value, it can be determined that there is activity below the door 3. In contrast, if the ratio of the intensity of the radio wave received by the first antenna 10 to the intensity of the radio wave received by the second antenna 20 (intensity of the radio wave received by the first antenna 10 / intensity of the radio wave received by the second antenna 20) is within a specified range, and both the intensity of the radio wave received by the first antenna 10 and the intensity of the radio wave received by the second antenna 20 are stronger than the specified values, it can be determined that there is activity of the leg 4A of a person 4 who intends to switch the state of the vehicle 2's door 3 and door lock on the side and below the door 3. Therefore, false detection can be prevented.

[0067] [Potential for industrial applications]

[0068] The technology of the present invention can be used to install a kicking sensor in a vehicle and detect the kicking motion of a human leg that is triggered by the control of the vehicle's doors.

Claims

1. A kicking sensor, disposed in a vehicle, for detecting the movement of a person's leg triggered by the control of a door of the vehicle, characterized in that, have: A first antenna receives radio waves from at least the side of the vehicle's doors; and The second antenna receives radio waves from at least below the doors of the aforementioned vehicle.

2. The kicking sensor according to claim 1, characterized in that, The first antenna described above is directional relative to the radio waves coming from the side described above.

3. The kicking sensor according to claim 1 or 2, characterized in that, The aforementioned second line is directional relative to the aforementioned radio waves originating from below.

4. The kicking sensor according to claim 1 or 2, characterized in that, The aforementioned first antenna and the aforementioned second antenna are composed of patterns formed on a single substrate.

5. The kicking sensor according to claim 4, characterized in that, The aforementioned substrate is disposed on the rear end of the vehicle with the surface of the substrate in which the first antenna and the second antenna are formed facing the rear side of the vehicle in the direction of travel.

6. The kicking sensor according to claim 1 or 2, characterized in that, The first antenna described above is capable of transmitting and receiving both vertically polarized and horizontally polarized radio waves.

7. The kicking sensor according to claim 1 or 2, characterized in that, The aforementioned first antenna is capable of transmitting radio waves to the aforementioned side. The aforementioned second antenna can transmit radio waves downwards.

8. The kicking sensor according to claim 1 or 2, characterized in that, It also has: The control unit alternately switches the states of the first antenna and the second antenna to a first state in which one of the first antenna and the second antenna transmits the radio waves, and a second state in which the other of the first antenna and the second antenna transmits the radio waves.

9. The kicking sensor according to claim 1 or 2, characterized in that, The ratio of the intensity of the radio wave received by the first antenna to the intensity of the radio wave received by the second antenna is used to determine whether the person's leg movement has occurred.

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