Urine volume estimation system, urine volume estimation method, and urine volume estimation program

Abstract

To easily evaluate expansion of a bladder into different directions.SOLUTION: A urine volume estimation system 100 comprises: an ultrasonic sensor 2 for transmitting an ultrasonic wave to the inside of a body of a subject and receiving a reflection wave; and an estimator 47 for estimating a urine volume of a bladder on the basis of a detection result of the ultrasonic sensor 2. The ultrasonic sensor 2 includes: a plurality of first ultrasonic sensors 21, whose ultrasonic wave transmission direction is shifted in a predetermined first direction X; and a plurality of second ultrasonic sensors 22, whose ultrasonic wave transmission direction is shifted in a second direction differing from the first direction X. The estimator 47 performs changeover between first estimation of estimating the urine volume of the bladder on the basis of detection results of the first ultrasonic sensors 21 and second estimation of estimating the urine volume of the bladder on the basis of detection results of the second ultrasonic sensors 22.SELECTED DRAWING: Figure 14

Description

Technical Field

[0001] The technology disclosed herein relates to a urine volume estimation system, a urine volume estimation method, and a urine volume estimation program.

Background Art

[0002] Conventionally, a system for estimating urine volume has been known. For example, the system disclosed in Patent Document 1 transmits ultrasonic waves into the body and estimates the urine volume in the bladder based on the reflected waves from the bladder.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The technology for estimating urine volume as described above transmits ultrasonic waves from a plurality of sensors toward different parts of the body and evaluates the expansion of the bladder based on the reflected waves. In such a technology, the evaluation of the expansion of the bladder varies depending on the part of the body toward which the ultrasonic waves are transmitted.

[0005] The technology disclosed herein has been made in view of such a point, and its object is to easily evaluate the expansion of the bladder in different directions.

Means for Solving the Problems

[0006] The urine volume estimation system disclosed herein includes an ultrasonic sensor that transmits ultrasonic waves into the body of a subject and receives reflected waves, and an estimator that estimates the urine volume in the bladder based on the detection result of the ultrasonic sensor. The ultrasonic sensor includes a plurality of first ultrasonic sensors whose ultrasonic wave transmission directions are shifted in a predetermined first direction, and a plurality of second ultrasonic sensors whose ultrasonic wave transmission directions are shifted in a second direction different from the first direction. The estimator switches between a first estimation that estimates the urine volume in the bladder based on the detection result of the first ultrasonic sensors, and a second estimation that estimates the urine volume in the bladder based on the detection result of the second ultrasonic sensors.

[0007] The urine volume estimation method disclosed herein includes performing a first estimation of estimating the urine volume in the bladder based on the reflected waves from the bladder of ultrasonic waves transmitted into the body of a subject using a plurality of first ultrasonic sensors whose ultrasonic wave transmission directions are shifted in a predetermined first direction, performing a second estimation of estimating the urine volume in the bladder based on the reflected waves from the bladder of ultrasonic waves transmitted into the body of a subject using a plurality of second ultrasonic sensors whose ultrasonic wave transmission directions are shifted in a second direction different from the first direction, and switching between the first estimation and the second estimation.

[0008] The urine volume estimation program disclosed herein causes a computer to realize a function of performing a first estimation of estimating the urine volume in the bladder based on the reflected waves from the bladder of ultrasonic waves transmitted into the body of a subject using a plurality of first ultrasonic sensors whose ultrasonic wave transmission directions are shifted in a predetermined first direction, a function of performing a second estimation of estimating the urine volume in the bladder based on the reflected waves from the bladder of ultrasonic waves transmitted into the body of a subject using a plurality of second ultrasonic sensors whose ultrasonic wave transmission directions are shifted in a second direction different from the first direction, and a function of switching between the first estimation and the second estimation.

Advantages of the Invention

[0009] According to the urine volume estimation system, it is possible to easily evaluate the expansion of the bladder in different directions.

[0010] According to the urine volume estimation method, the expansion of the bladder in different directions can be easily evaluated.

[0011] According to the urine volume estimation program, the expansion of the bladder in different directions can be easily evaluated.

Brief Description of the Drawings

[0012]

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DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, exemplary embodiments will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram of a urine volume estimation system 100.

[0014] The urine volume estimation system 100 includes an ultrasonic sensor 2 that transmits ultrasonic waves into the body of a subject and receives reflected waves, and an arithmetic unit 4 that estimates the urine volume in the bladder based on the detection results of the ultrasonic sensor 2. The urine volume estimation system 100 estimates the urine volume in the bladder of the subject using ultrasonic waves. For example, the subject includes not only healthy persons but also care recipients such as the elderly or disabled persons, or persons who are not care recipients but have physical disabilities and require time to go to the toilet. However, the subject is not limited thereto.

[0015] The urine volume estimation system 100 includes a probe 1 that includes the ultrasonic sensor 2. The probe 1 communicates with the arithmetic unit 4. For example, the probe 1 and the arithmetic unit 4 perform wireless communication.

[0016] 〈Probe〉 FIG. 2 is a schematic perspective view of the probe 1. FIG. 3 is a block diagram of the probe 1. The probe 1 has an ultrasonic sensor 2 and a control device 3 for controlling the ultrasonic sensor 2. The probe 1 further has a casing 10 that houses the ultrasonic sensor 2 and the control device 3. The casing 10 is formed in a flat shape. The casing 10 has a contact surface 11 that contacts the skin of the subject's abdomen when the probe 1 is worn by the subject. The casing 10 has a main body 12 having an internal space and a lid 13 attached to the main body 12. The main body 12 includes the contact surface 11.

[0017] FIG. 4 is a diagram showing the wearing state of the probe 1. The probe 1 is constantly worn by the subject. The probe 1 is disposed on the skin of the subject's abdomen at a portion corresponding to the bladder (for example, the lower abdomen). For example, the probe 1 is attached to the abdomen via an adhesive sheet 18 with the contact surface 11 in contact with the subject's abdomen. The adhesive sheet 18 has an adhesive surface and is adhered to the abdomen via the adhesive surface. The adhesive sheet 18 has a holder 19 that detachably holds the probe 1. The adhesive sheet 18 and the holder 19 have an opening through which the probe 1 is exposed to the body surface. The probe 1 held by the holder 19 contacts the body surface through the opening. A gel or the like for improving the transmission of ultrasonic waves to the abdomen may be applied between the contact surface 11 and the abdomen. Note that the probe 1 may be attached to the subject by a method other than the adhesive sheet 18, for example, via a belt.

[0018] The ultrasonic sensor 2 transmits and receives ultrasonic waves. Specifically, the ultrasonic sensor 2 includes a piezoelectric element. The piezoelectric element vibrates according to a driving voltage to generate ultrasonic waves, and when receiving ultrasonic waves, generates an electrical signal according to the vibration. The ultrasonic sensor 2 transmits ultrasonic waves toward the subject, that is, from the contact surface 11 of the casing 10.

[0019] FIG. 5 is a diagram showing the inside of the casing 10 with the lid 13 removed. The ultrasonic sensor 2 includes a plurality of first ultrasonic sensors 21 whose ultrasonic transmission directions are shifted in a predetermined first direction X, and a plurality of second ultrasonic sensors 22 whose ultrasonic transmission directions are shifted in a second direction Y different from the first direction. Hereinafter, the direction in which the ultrasonic transmission directions of the first ultrasonic sensor 21 and the second ultrasonic sensor 22 are shifted is referred to as the "shift direction". That is, the shift direction of the plurality of first ultrasonic sensors 21 is the first direction X, and the shift direction of the plurality of second ultrasonic sensors 22 is the second direction Y. In this example, the first direction X and the second direction Y are orthogonal to each other. The probe 1 is attached to the subject such that the first direction X faces the vertical direction of the human body and the second direction Y faces the horizontal direction (i.e., the left-right direction) of the human body. That is, with respect to the subject, the first direction X is the vertical direction and the second direction Y is the horizontal direction.

[0020] In this example, the ultrasonic sensor 2 includes four first ultrasonic sensors 21 and three second ultrasonic sensors 22. However, one of the first ultrasonic sensors 21 also serves as the second ultrasonic sensor 22. Therefore, the total number of ultrasonic sensors 2 is six. When the first ultrasonic sensor 21 and the second ultrasonic sensor 22 are not distinguished, they are simply referred to as the "ultrasonic sensor 2".

[0021] Each of the four first ultrasonic sensors 21 transmits ultrasonic waves toward different portions in the body of the object where the positions in the first direction X are different. Specifically, the four first ultrasonic sensors 21 are arranged side by side in the first direction X within the casing 10. That is, the positions of the four first ultrasonic sensors 21 in the first direction X are different from each other. When the four first ultrasonic sensors 21 are distinguished, an alphabet is added to the end of the reference numeral. The four first ultrasonic sensors 21 are referred to as the first ultrasonic sensor 21a, the first ultrasonic sensor 21b, the first ultrasonic sensor 21c, and the first ultrasonic sensor 21d in order from the bottom in the first direction X.

[0022] Furthermore, the ultrasonic transmission angles of the four first ultrasonic sensors 21, specifically, the elevation angles of the transmission directions, are different from each other. That is, the transmission directions of the four first ultrasonic sensors 21 are non-parallel to each other. FIG. 6 is a cross-sectional view of the probe 1 taken along line VI-VI in FIG. 5. The four first ultrasonic sensors 21 transmit ultrasonic waves radially in the vertical direction. Specifically, the transmission direction of the third first ultrasonic sensor 21c from the bottom is perpendicular to the contact surface 11. The transmission direction of the uppermost first ultrasonic sensor 21d is upward relative to the transmission direction of the first ultrasonic sensor 21c. The transmission direction of the second first ultrasonic sensor 21b from the bottom is downward relative to the transmission direction of the first ultrasonic sensor 21c. The transmission direction of the lowermost first ultrasonic sensor 21a is downward relative to the transmission direction of the first ultrasonic sensor 21b.

[0023] In addition, the left-right angles of the transmission directions of the four first ultrasonic sensors 21 are substantially the same. For example, with respect to the left-right direction, that is, the horizontal direction, the four first ultrasonic sensors 21 transmit ultrasonic waves toward the center of the subject, specifically, the midline.

[0024] As shown in Fig. 5, each of the three second ultrasonic sensors 22 transmits ultrasonic waves toward different portions in the body of the object where the positions in the second direction Y are different. In this example, the third first ultrasonic sensor 21c from the bottom functions as the second ultrasonic sensor 22. Therefore, when explaining the configuration as the second ultrasonic sensor 22 with respect to the third first ultrasonic sensor 21c from the bottom, the first ultrasonic sensor 21c is referred to as the second ultrasonic sensor 22. Specifically, the three second ultrasonic sensors 22 are arranged side by side in the second direction Y within the casing 10. That is, the positions of the three second ultrasonic sensors 22 in the second direction Y are different from each other. When distinguishing the three second ultrasonic sensors 22, an alphabet is appended to the end of the reference numeral. The three second ultrasonic sensors 22 are referred to as the second ultrasonic sensor 22a, the second ultrasonic sensor 22b, and the second ultrasonic sensor 22c in order from the right side of the subject in the second direction Y. The second ultrasonic sensor 22b is also the first ultrasonic sensor 21c. The column of the three second ultrasonic sensors 22 intersects the column of the four first ultrasonic sensors 21. At the intersection point, the first ultrasonic sensor 21c, that is, the second ultrasonic sensor 22b is arranged.

[0025] Furthermore, the ultrasonic transmission angles of the three second ultrasonic sensors 22, specifically, the angles to the left and right of the transmission direction are different from each other. That is, the transmission directions of the three second ultrasonic sensors 22 are non-parallel to each other. Fig. 7 is a cross-sectional view of the probe 1 taken along line VII-VII in Fig. 5. The three second ultrasonic sensors 22 transmit ultrasonic waves radially in the left and right directions. Specifically, the transmission direction of the middle second ultrasonic sensor 22b is perpendicular to the contact surface 11. The transmission direction of the right second ultrasonic sensor 22a is more rightward than the transmission direction of the second ultrasonic sensor 22b. The transmission direction of the left second ultrasonic sensor 22c is more leftward than the transmission direction of the second ultrasonic sensor 22b.

[0026] In addition, the elevation angles of the transmission directions of the three second ultrasonic sensors 22 are substantially the same.

[0027] FIG. 8 is a schematic cross-sectional view of the lower abdomen of a human body wearing the probe 1. The urinary bladder 91 is located in the lower abdomen. The pubic bone 92 is located obliquely downward in front of the urinary bladder 91.

[0028] The probe 1 is attached to the abdomen of the subject so that the ultrasonic wave emitted from the first ultrasonic sensor 21 spreads in the vertical direction and the ultrasonic wave emitted from the second ultrasonic sensor 22 spreads in the horizontal direction. The first ultrasonic sensor 21 transmits ultrasonic waves toward different positions in the vertical direction inside the body. The second ultrasonic sensor 22 transmits ultrasonic waves toward different positions in the horizontal direction inside the body. The urinary bladder 91 expands three-dimensionally as the urine volume increases. Therefore, the different positions in the vertical direction and the different positions in the horizontal direction are respectively the directions in which the urinary bladder 91 expands. Incidentally, the urinary bladder 91 expands significantly particularly in the vertical direction. That is, the first ultrasonic sensor 21 is arranged to transmit ultrasonic waves toward different positions in the direction in which the urinary bladder 91 expands relatively largely.

[0029] <〈Control Device〉> The control device 3 is arranged on the substrate 15. The substrate 15 is housed in the casing 10 as shown in FIG. 6 (see also FIG. 7). As shown in FIG. 3, the control device 3 includes a transmitter 31 that outputs a drive voltage to the ultrasonic sensor 2, a receiver 32 that receives a received signal from the ultrasonic sensor 2, a switch 33 that switches the ultrasonic sensor 2 connected to the transmitter 31 and the receiver 32, a notifier 35 for notifying various information to the outside, a communicator 36 for communicating with the outside, a storage 37 that stores various programs and data, a processor 38 that performs overall control of the control device 3, and a memory 39.

[0030] The transmitter 31 supplies a drive voltage to the ultrasonic sensor 2. The transmitter 31 includes a pulse generator 31a and an amplifier 31b. The pulse generator 31a generates a pulse signal having a predetermined pulse width and voltage value. The pulse generator 31a may be configured to be able to change the pulse width, the number of pulses, and the frequency. The amplifier 31b amplifies the pulse signal from the pulse generator 31a and outputs it to the ultrasonic sensor 2 as a drive voltage.

[0031] The receiver 32 receives the electrical signal from the ultrasonic sensor 2. The receiver 32 includes an amplifier 32a, a detector 32b, and an A / D converter 32c. The amplifier 32a amplifies the received signal from the ultrasonic sensor 2. The detector 32b performs envelope detection on the amplified received signal. Note that the detector 32b may amplify the received signal after detection. The A / D converter 32c performs A / D conversion on the received signal after detection.

[0032] The switch 33 selectively switches the ultrasonic sensor 2 connected to the transmitter 31 and the receiver 32 from among the plurality of ultrasonic sensors 2.

[0033] The notifier 35 is, for example, an LED lamp. Various information (e.g., presence of urination) is notified to the subject according to the lighting mode of the LED lamp.

[0034] The communicator 36 is a communication module and communicates with an external communication device such as the arithmetic unit 4. For example, the communicator 36 performs communication according to the Bluetooth (registered trademark) standard. As shown in FIG. 1, the communicator 36 may be connected to the Internet via the relay 52 and communicate with the server 51 or the like.

[0035] The storage 37 is a computer-readable recording medium and is composed of, for example, a flash memory. The storage 37 stores various programs and various information necessary for the execution of the processing by the processor 38. Further, the storage 37 stores the received signal received by the receiver 32 and the information acquired from the outside via the communicator 36 and the like.

[0036] The processor 38 controls the transmitter 31, the receiver 32, the switch 33, the notifier 35, and the communicator 36 based on the program stored in the memory 37. The processor 38 is composed of a processor such as a CPU (Central Processing Unit), for example. The processor 38 executes various processes by expanding and executing the program stored in the memory 37 or the like in the memory 39. Note that the processor 38 may be realized by hardware such as an LSI (Large Scale Integration) having the same functions as a processor.

[0037] Specifically, the processor 38 receives a signal from the outside. For example, the processor 38 receives a signal from an external device such as the arithmetic unit 4 via the communicator 36 and performs processing according to the signal (for example, operates the notifier 35). The processor 38 receives a measurement command from the arithmetic unit 4. The processor 38 executes transmission and reception of ultrasonic waves by the ultrasonic sensor 2. For example, the processor 38 controls the switch 33 to switch the ultrasonic sensor 2 connected to the transmitter 31 and the receiver 32. The processor 38 controls the transmitter 31 to output a drive voltage to the ultrasonic sensor 2. The processor 38 controls the receiver 32 to convert the reception signal of the ultrasonic sensor 2 into a digital signal. The processor 38 controls the communicator 36 to transmit a signal to an external device such as the arithmetic unit 4. For example, the processor 38 transmits the reception signal of the ultrasonic sensor 2 to the outside.

[0038] The memory 39 is a computer-readable recording medium and is composed of, for example, a ROM (Read Only Memory), an EPROM (Erasable Programmable ROM), an EEPROM (Electrically Erasable Programmable ROM), or a RAM (Random Access Memory), etc.

[0039] 〈Arithmetic Unit〉 The computing device 4 is a portable smart device such as a smartphone or a tablet terminal. The computing device 4 can communicate with the probe 1, receive and store the received signal transmitted from the probe 1 (that is, the received signal (received wave) of the ultrasonic sensor 2 received and processed by the receiver 32). Hereinafter, the received signal received from the probe 1 is also simply referred to as "the received signal of the ultrasonic sensor 2". Further, the computing device 4 analyzes the stored received signal of the ultrasonic sensor 2. Specifically, the computing device 4 estimates the urine volume in the bladder based on the received signal of the ultrasonic sensor 2. The computing device 4 stores a program and data for estimating the urine volume and the like.

[0040] The computing device 4 can operate an application program dedicated to the urine volume estimation system 100 (hereinafter simply referred to as "dedicated app"). By using the dedicated app, the computing device 4 executes signal transmission and reception with the probe 1, analysis of the received signal of the ultrasonic sensor 2, and the like.

[0041] The computing device 4 may store information about the subject. The information about the subject is, for example, a user ID for identifying the subject, a device ID for identifying the probe 1, and information related to urine storage and urination of the subject. The user ID and the device ID are registered in advance by the user. The information related to urine storage and urination of the subject is, for example, the allowable urine volume (the allowable urine level described later), and a common initial value is set in advance by default.

[0042] FIG. 9 is a block diagram showing the hardware configuration of the computing device 4. The computing device 4 includes a processor 41, a memory 42, a communicator 43, and a storage 44. Note that the computing device 4 may further include a touch panel.

[0043] The processor 41 is composed of a processor such as a CPU (Central Processing Unit). The processor 41 executes various processes by expanding and executing a program stored in a storage device 44 or the like in the memory 42. Note that the processor 41 may be realized by hardware such as an LSI (Large Scale Integration) having the same functions as a processor.

[0044] The memory 42 is a computer-readable recording medium and is composed of, for example, a ROM (Read Only Memory), an EPROM (Erasable Programmable ROM), an EEPROM (Electrically Erasable Programmable ROM), or a RAM (Random Access Memory).

[0045] The communicator 43 is a communication module and communicates with the control device 3 of the probe 1. For example, the communicator 43 performs communication according to the Bluetooth (registered trademark) standard. Further, the communicator 43 may communicate with an external device such as a server 51 other than the probe 1 by performing mobile communication and / or Wi-Fi communication.

[0046] The storage device 44 is a computer-readable recording medium. The storage device 44 stores various programs and various information necessary for the execution of the processes of the processor 41. For example, the storage device 44 stores a urine volume estimation program 81 and thresholds used for urine volume estimation. The urine volume estimation program 81 causes the processor 41 as a computer to continuously estimate the urine volume in the bladder based on the reflected wave from the bladder received by the ultrasonic sensor 2 that transmits ultrasonic waves into the body of the subject and receives the reflected waves.

[0047] FIG. 10 is a block diagram showing the functional configuration of the processor 41. The processor 41 realizes the functions shown in FIG. 10 by expanding and executing the urine volume estimation program 81 etc. in the memory 42. The processor 41 has an indicator 45, an acquirer 46, and an estimator 47. The reception function, the acquisition function, and the estimation function are realized by the processor 41 executing the urine volume estimation program 81 stored in the storage 44.

[0048] The indicator 45 outputs commands to each part of the user terminal 4 or the probe 1. The indicator 45 receives operation inputs from a user such as a subject. The arithmetic unit 4 displays various screens and images on the display. For example, the arithmetic unit 4 displays the screen of the urine volume estimation application on the display. The application screen includes the estimated urine volume and operation buttons etc. For example, the application screen displays an execution button for the second estimation described later. When the user touches the execution button for the second estimation, the indicator 45 receives the execution input for the second estimation. When the indicator 45 receives the execution input for the second estimation, it outputs a measurement command to the probe 1, specifically, the control device 3.

[0049] The acquirer 46 receives, that is, acquires, the received signal of the ultrasonic sensor 2 by communicating with the probe 1. The acquirer 46 stores the received signal in the storage 44 together with the time when the received signal is received (that is, the acquisition time). The arithmetic unit 4 accumulates the received signal and the acquisition time.

[0050] The estimator 47 estimates the urine volume in the bladder based on the received signal of the ultrasonic sensor 2, that is, the detection result of the ultrasonic sensor 2. The estimator 47 continuously estimates the urine volume in the bladder. Specifically, the estimator 47 analyzes the received signal of the ultrasonic sensor 2 stored in the storage 44. The estimator 47 continuously estimates the urine volume in the bladder based on the reflected wave from the bladder received by the ultrasonic sensor 2, and stores the estimated urine volume in the storage 44.

[0051] The estimator 47 switches between a first estimation for estimating the urine volume in the bladder based on the detection result of the first ultrasonic sensor 21 and a second estimation for estimating the urine volume in the bladder based on the detection result of the second ultrasonic sensor 22. The estimation accuracy of the second estimation is higher than that of the first estimation. In other words, the first estimation is a rough estimation of the urine volume, and the second estimation is a more detailed estimation of the urine volume. In the first estimation, the urine volume in the bladder is estimated based on the detection result of the first ultrasonic sensor 21. In the first estimation, the detection result of the second ultrasonic sensor 22 is not used. In the second estimation, the urine volume in the bladder is estimated based on the detection result of the second ultrasonic sensor 22. In the second estimation, at least the detection result of the second ultrasonic sensor 22 is used. Further, the estimation methods of the first estimation and the second estimation may be different.

[0052] In the first estimation, the estimator 47 estimates the urine volume in the bladder based on the number of the first ultrasonic sensors 21 that receive the reflected waves from the bladder. Specifically, the estimator 47 examines the presence or absence of the detection of the bladder in each of the received signals of the four first ultrasonic sensors 21. The estimator 47 examines whether each of the received signals of the four first ultrasonic sensors 21 contains the reflected wave of the bladder. The reception time zone in which the reflected wave of the bladder is expected to return is generally known. The estimator 47 determines whether the reflected wave exists in the reception time zone. For example, in the first estimation, the reflected wave from the rear wall of the bladder is used. The estimator 47 determines that the first ultrasonic sensor 21 has detected the bladder when the received signal contains the reflected wave of the bladder.

[0053] Thereafter, the estimator 47 determines the urine level based on which of the first ultrasonic sensors 21 has detected the bladder. The bladder expands upward as the urine volume increases, while the plurality of first ultrasonic sensors 21 transmit ultrasonic waves toward different positions in the vertical direction as shown in FIG. 8. Therefore, the larger the urine volume, the larger the number of first ultrasonic sensors 21 that detect the bladder. The estimator 47 determines the urine level according to which of the first ultrasonic sensors 21, starting from the bottom, has detected the bladder. The urine level is set to "0" when none of the first ultrasonic sensors 21 has detected the bladder. The urine level is set to "2.5" when the uppermost sensor that detects the bladder is the first ultrasonic sensor 21a. The urine level is set to "5" when the uppermost sensor that detects the bladder is the first ultrasonic sensor 21b. The urine level is set to "7.5" when the uppermost sensor that detects the bladder is the first ultrasonic sensor 21c. The urine level is set to "10" when the uppermost sensor that detects the bladder is the first ultrasonic sensor 21d. That is, the urine level is evaluated in the range of 0 to 10.

[0054] The estimator 47 averages the urine levels of the most recent predetermined number of detections including the urine level of the current detection to obtain the final urine level of the current time. For example, the estimator 47 rounds the average value of the plurality of urine levels and represents the current urine level as a number with one digit after the decimal point. The estimator 47 stores the current urine level in the storage 44 together with the time of the estimation timing. The estimator 47 may display the current urine level on the application screen of the arithmetic unit 4.

[0055] On the other hand, in the second estimation, the estimator 47 obtains the expansion of the bladder in the ultrasonic transmission direction from each of the second ultrasonic sensors 22 based on the detection results of the second ultrasonic sensors 22, and estimates the urine volume in the bladder based on the obtained expansion of the bladder. In this example, the estimator 47 performs the second estimation using the detection results of both the first ultrasonic sensor 21 and the second ultrasonic sensor 22. Specifically, the estimator 47 obtains the depth of the bladder based on the reception signals of each of the four first ultrasonic sensors 21 and two (three including the shared first ultrasonic sensor 21. The same applies hereinafter) second ultrasonic sensors 22, and estimates the capacity of the bladder based on the depth of the bladder corresponding to each of the four first ultrasonic sensors 21 and two second ultrasonic sensors 22. The estimator 47 obtains the positions of the front wall and the rear wall of the bladder in the ultrasonic transmission direction of each of the four first ultrasonic sensors 21 and two second ultrasonic sensors 22 based on the reflected wave from the front wall of the bladder and the reflected wave from the rear wall of the bladder included in the reception signal. The estimator 47 obtains the positions of the front wall and the rear wall of the bladder based on the reception time of the reflected wave, the propagation time of the ultrasonic wave, and the ultrasonic transmission direction. Thereby, the positions of the front wall and the rear wall of the bladder in a maximum of six directions, that is, the positions of a maximum of 12 walls of the bladder are obtained.

[0056] The estimator 47 estimates the bladder volume based on the positions of the walls at multiple locations of the bladder that are obtained. FIG. 11 is an explanatory diagram for estimating the shape of the bladder based on the detection result of the first ultrasonic sensor 21. FIG. 12 is an explanatory diagram for estimating the shape of the bladder based on the detection result of the second ultrasonic sensor 22. For example, the estimator 47 calculates a solid that approximates the bladder from the positions of the walls at multiple locations of the bladder. The approximating solid is, for example, an ellipsoid. Specifically, since the four first ultrasonic sensors 21 each transmit ultrasonic waves in directions where the left-right direction is the same and the up-down direction is different, as shown in FIG. 11, from the received signals of the four first ultrasonic sensors 21, the positions of the walls at multiple locations in the cross-section that expands in the up-down direction and the front-back direction, that is, the cross-section orthogonal to the left-right direction, are obtained. The estimator 47 obtains an ellipse E1 that approximates the bladder in the cross-section orthogonal to the left-right direction from the positions of the multiple walls. On the other hand, since the three second ultrasonic sensors 22 each transmit ultrasonic waves in directions where the up-down direction is the same and the left-right direction is different, as shown in FIG. 12, from the received signals of the three second ultrasonic sensors 22, the positions of the walls at multiple locations in the cross-section that expands in the left-right direction and the front-back direction, that is, the cross-section orthogonal to the up-down direction, are obtained. The estimator 47 obtains an ellipse E2 that approximates the bladder in the cross-section orthogonal to the up-down direction from the positions of the multiple walls. The estimator 47 obtains an ellipsoid that approximates the bladder based on the approximate ellipses E1 and E2 of the bladder in the two orthogonal cross-sections. The estimator 47 estimates the volume of the obtained approximating ellipsoid as the urine volume in the bladder. The estimator 47 stores the estimated urine volume in the storage 44 together with the time at the estimation timing. The estimator 47 may display the estimated urine volume on the application screen of the arithmetic unit 4.

[0057] Thus, in the first estimation of this example, the urine volume in the bladder is estimated based on the expansion of the bladder in the one-dimensional direction, specifically, the up-down direction. In the first estimation, the urine volume is represented by an index called the urine level. On the other hand, in the second estimation, the urine volume in the bladder is estimated based on the expansion of the bladder in the three-dimensional direction, specifically, the up-down direction, the left-right direction, and the front-back direction. In the second estimation, the urine volume is represented by the bladder volume.

[0058] The estimator 47 normally performs the first estimation and switches the first estimation to the second estimation when a predetermined switching condition is satisfied. For example, the switching condition is the receipt of an execution command for the second estimation. For example, the arithmetic unit 4 causes the display to display an application screen. An execution button for the second estimation is displayed on the application screen. The user touches the execution button as an execution operation for the second estimation. When the execution button is operated, the indicator 45 outputs an execution command for the second estimation to the estimator 47. When receiving the execution command for the second estimation, the estimator 47 switches the first estimation to the second estimation and executes the second estimation. In this example, when the second estimation is completed, the estimator 47 switches the first estimation to the second estimation. That is, the switching condition from the second estimation to the first estimation is the completion of the second estimation.

[0059] <Operation of Urine Volume Estimation System> Hereinafter, the processing of the urine volume estimation system 100 will be described in detail. First, the operation of the probe 1 will be described. The probe 1 transmits and receives ultrasonic waves under the control of the control device 3. FIG. 13 is a flowchart of the basic processing of the control device 3.

[0060] Specifically, in step S101, the processor 38 determines whether the measurement conditions are satisfied. The measurement conditions are the conditions for performing ultrasonic wave transmission and reception. In this example, the measurement conditions include a first measurement condition and a second measurement condition. The first measurement condition is that a predetermined measurement timing arrives. The measurement timing is the timing for performing ultrasonic wave transmission and reception for the first estimation and is repeated at a predetermined measurement period. The second measurement condition is to receive a measurement command from the outside (for example, the arithmetic unit 4).

[0061] The processor 38 determines whether either the first measurement condition or the second measurement condition is satisfied. The processor 38 measures time and monitors the arrival of the measurement timing, and also monitors the reception of the measurement command. When the measurement timing arrives or the measurement command is received, the processor 38 determines that the measurement conditions are satisfied. Until the measurement conditions are satisfied, the processor 38 repeats step S101. That is, the processor 38 waits for the measurement conditions to be satisfied.

[0062] When the measurement conditions are satisfied, in step S102, the processor 38 causes the four first ultrasonic sensors 21 and the two second ultrasonic sensors 22 to transmit and receive ultrasonic waves in sequence while switching the switch 33. For example, the processor 38 controls the switch 33 so that the first ultrasonic sensor 21a is connected to the transmitter 31 and the receiver 32. Then, the processor 38 outputs a generation command for a pulse signal to the transmitter 31, and causes the transmitter 31 to supply a driving voltage to the first ultrasonic sensor 21a. The first ultrasonic sensor 21a transmits ultrasonic waves based on the driving voltage and receives reflected waves from inside the body. The received signal of the first ultrasonic sensor 21a is amplified, detected, and A / D converted by the receiver 32. The processor 38 stores the received signal after A / D conversion in the memory 39. The processor 38 sequentially switches the switch 33 and executes the same control for the other ultrasonic sensors 2 as well.

[0063] When the transmission and reception of ultrasonic waves by all the ultrasonic sensors 2 are completed, in step S103, the processor 38 transmits the received signals of the first ultrasonic sensors 21 and the second ultrasonic sensors 22 stored in the memory 39 to the arithmetic unit 4 via the communicator 36. Then, the processor 38 returns to step S101 and repeats the processing from step S101.

[0064] In this way, every time the measurement conditions are satisfied, the processor 38 executes the transmission and reception of ultrasonic waves by all the ultrasonic sensors 2 and the transmission of the received signals to the arithmetic unit 4. The processor 38 periodically performs the transmission and reception of ultrasonic waves by the ultrasonic sensors 2 at the measurement timing, and performs the transmission and reception of ultrasonic waves by the ultrasonic sensors 2 when a measurement command is received.

[0065] Subsequently, the processing of the arithmetic unit 4 will be described. FIG. 14 is a flowchart of the basic processing of the arithmetic unit 4. The arithmetic unit 4 executes the following processing by expanding and executing a urine volume estimation program 81 and the like in the memory 42.

[0066] In step S201, the indicator 45 determines whether it has received an execution input for the second estimation. As described above, when the user touches the execution button for the second estimation on the application screen of the computing device 4, the indicator 45 receives the execution input for the second estimation. Step S201 corresponds to switching between the first estimation and the second estimation.

[0067] If the indicator 45 has not received the execution input for the second estimation, in step S202, the estimator 47 determines whether the estimation timing has arrived. The estimation timing repeats at a predetermined estimation period. In this example, the estimation period is the same as the measurement period.

[0068] If the estimation timing has not arrived, the indicator 45 returns to the process of step S201. That is, the arrival of the estimation timing and the reception of the execution input for the second estimation are awaited.

[0069] If the estimation timing has arrived, in step S203, the estimator 47 executes the first estimation. The estimator 47 obtains the urine level based on the latest received signals of the four first ultrasonic sensors 21. Then, the estimator 47 obtains the average value of a predetermined number of the latest urine levels including the urine level of the latest received signals of the four first ultrasonic sensors 21 as the final current urine level. The final current urine level can be output in various manners. For example, the estimator 47 may display the final current urine level on the display of the computing device 4. The estimator 47 may transmit the final current urine level to an external device such as the server 51. The estimator 47 may store the final current urine level in the storage 44. Step S203 corresponds to executing the first estimation.

[0070] When the first estimation is completed, the indicator 45 returns to the process of step S201. That is, the estimator 47 periodically executes the first estimation at the estimation timing unless the indicator 45 receives the execution input for the second estimation.

[0071] On the other hand, when the indicator 45 receives the execution input of the second estimation, in step S204, the indicator 45 outputs a measurement command to the probe 1. The measurement command is transmitted to the probe 1 via the communicator 43. Thereby, the probe 1 executes the transmission and reception of ultrasonic waves for the second estimation.

[0072] Thereafter, in step S205, the indicator 45 determines whether it has received the reception signal of the ultrasonic sensor 2 from the probe 1. Specifically, the indicator 45 determines whether the acquirer 46 has received the reception signal of the ultrasonic sensor 2. The indicator 45 repeats step S205 until the reception signal of the ultrasonic sensor 2 is received. That is, the indicator 45 waits until the reception signal of the ultrasonic sensor 2 is returned in response to the measurement command.

[0073] When the reception signal of the ultrasonic sensor 2 is received, in step S206, the indicator 45 outputs an execution command for the second estimation to the estimator 47. The estimator 47 executes the second estimation upon receiving the execution command. The estimator 47 calculates the urine volume based on the latest reception signals of the four first ultrasonic sensors 21 and the latest reception signals of the two second ultrasonic sensors 22. In the second estimation, the estimated urine volume is output as a quantity rather than a urine level. The estimated urine volume can be output in various manners. For example, the estimator 47 may display the estimated urine volume on the display of the arithmetic unit 4. The estimator 47 may transmit the estimated urine volume to an external device. The estimator 47 may store the estimated urine volume in the storage 44. Step S206 corresponds to executing the second estimation.

[0074] When the second estimation is completed, the indicator 45 returns to the process of step S201. That is, the estimator 47 periodically executes the first estimation as described above and executes the interrupt process of the second estimation when it receives the execution command of the second estimation.

[0075] In this way, the first estimation for estimating the urine volume based on the detection result of the first ultrasonic sensor 21 and the second estimation for estimating the urine volume based on the detection result of the second ultrasonic sensor 22 are switched and executed. The first ultrasonic sensor 21 and the second ultrasonic sensor 22 have different shift directions of the ultrasonic transmission direction. That is, the detection results of the first ultrasonic sensor 21 and the second ultrasonic sensor 22 can evaluate the expansion of the bladder in different directions. That is, by switching between the first estimation and the second estimation, the urine volume in the bladder can be evaluated from different viewpoints.

[0076] In addition, in the second estimation of this example, the urine volume is estimated based on both the detection result of the first ultrasonic sensor 21 and the detection result of the second ultrasonic sensor 22. That is, in the second estimation, in addition to the shift direction of the second ultrasonic sensor 22, the expansion of the bladder in the shift direction of the first ultrasonic sensor 21 is also evaluated. Thereby, in the second estimation, the urine volume is estimated with higher accuracy than in the first estimation.

[0077] Furthermore, in the first estimation, the urine volume in the bladder is estimated based on the number of the first ultrasonic sensors 21 that receive the reflected waves from the bladder. On the other hand, in the second estimation, the expansion of the bladder in the transmission direction of the second ultrasonic sensor 22 is obtained from the detection result of the second ultrasonic sensor 22, and the urine volume in the bladder is estimated based on the obtained expansion of the bladder. That is, the computational load of the first estimation is reduced compared to the second estimation. The estimation accuracy of the second estimation is higher than that of the first estimation. Thereby, by switching between the first estimation and the second estimation, the urine volume estimation with a low computational load and the urine volume estimation with a high estimation accuracy can be properly used.

[0078] In this example, the first estimation is usually executed, and the second estimation is executed when there is an execution input. In this example, the execution input is output when the user performs an execution operation of the second estimation in the application. Therefore, the first estimation is usually executed with a low computational load, and the second estimation with high accuracy is executed according to the user's intention. The computational load can be reduced by the first estimation during normal times. For example, since the urgency of urination is low during normal times, the approximate urine volume can be monitored by executing the first estimation to predict the timing of urination. And when the user wants to know the detailed urine volume, the second estimation is executed according to the user's intention. For example, the detailed urine volume can be obtained by executing the second estimation before and after urination.

[0079] <Variant Example 1> Next, a variant example of the urine volume estimation system 100 will be described. The urine volume estimation system 100 according to Variant Example 1 is different from the aforementioned urine volume estimation system 100 in the conditions under which the second estimation is executed.

[0080] Specifically, in the urine volume estimation system 100 according to Variant Example 1, the estimator 47 switches between the first estimation and the second estimation according to the urine volume. When the urine volume is relatively small, the estimator 47 performs the first estimation, and when the urine volume is relatively large, the estimator 47 performs the second estimation. In Variant Example 1, the second estimation is also executed at the same estimation timing as the first estimation. Therefore, the measurement conditions of the probe 1 include the first measurement conditions and do not include the second measurement conditions. That is, the probe 1 executes the transmission and reception of ultrasonic waves at periodic measurement timings and transmits the received signal to the arithmetic unit 4.

[0081] FIG. 15 is a flowchart of the processing of the arithmetic unit 4 in the urine volume estimation system 100 according to Variant Example 1. The estimator 47 determines in step S301 whether the estimation timing has arrived. The estimation timing repeats at a predetermined estimation period.

[0082] If the estimation timing has not arrived, the estimator 47 repeats the process of step S301. That is, the estimator 47 waits for the arrival of the estimation timing.

[0083] When the estimated timing arrives, the estimator 47 determines, in step S302, whether or not the most recent estimated urine volume is equal to or greater than a predetermined threshold α. The most recent estimated urine volume is the urine volume estimated at the previous estimated timing, regardless of whether it is based on the first estimation or the second estimation. In this example, since the expression forms of the estimated urine volume based on the first estimation and the estimated urine volume based on the second estimation are different, the threshold α is set for each of the estimated urine volume based on the first estimation and the estimated urine volume based on the second estimation. That is, a threshold α expressed in terms of urine level and a threshold α expressed in terms of urine volume are set. The urine volume corresponding to the threshold α expressed in terms of urine level is approximately equal to the threshold α expressed in terms of urine volume. When the previous urine volume estimation is the first estimation, the estimator 47 makes the determination in step S302 using the threshold α expressed in terms of urine level. When the previous urine volume estimation is the second estimation, the estimator 47 makes the determination in step S302 using the threshold α expressed in terms of urine volume. The threshold α is stored in the storage device 44. Step S302 corresponds to switching between the first estimation and the second estimation.

[0084] When the most recent estimated urine volume is less than the threshold α, the estimator 47 executes the first estimation in step S303. The process of step 303 is the same as the process of step 203. When the first estimation is completed, the estimator 47 returns to the process of step S301. Step S303 corresponds to executing the first estimation.

[0085] When the most recent estimated urine volume is equal to or greater than the threshold α, the estimator 47 executes the second estimation in step S304. In this example, the estimator 47 executes the second estimation at the estimated timing in the same manner as in the case of the first estimation. The received signal of the ultrasonic sensor 2 used in the second estimation is the latest of the received signals of the ultrasonic sensor 2 that are periodically transmitted from the probe 1. The method for calculating the urine volume by the second estimation is the same as that in step S206. When the second estimation is completed, the estimator 47 returns to the process of step S301. Step S304 corresponds to executing the second estimation.

[0086] Thus, in Modification 1, urine volume estimation by the first estimation or the second estimation is periodically performed at the estimated timing. The first estimation and the second estimation are selected according to the urine volume. Specifically, the first estimation is performed when the urine volume is relatively small, and the second estimation is performed when the urine volume is relatively large. The urgency of urination increases as the urine volume increases. Therefore, by performing the second estimation when the urine volume is relatively large, the timing of urination can be predicted based on the highly accurate estimated urine volume. On the other hand, when the urine volume is relatively small, the urine volume can be monitored while reducing the computational load.

[0087] <Modification 2> Subsequently, the urine volume estimation system 100 according to Modification 2 will be described. The urine volume estimation system 100 according to Modification 2 is different from the aforementioned basic urine volume estimation system 100 under the condition where the second estimation is performed. Among the configurations of the urine volume estimation system 100 according to Modification 2 that are different from the basic urine volume estimation system 100, the components are numbered in the 300s. Among the components numbered in the 300s, those with the same units digit and below as the corresponding components of the basic urine volume estimation system have the same functions as the corresponding components of the basic urine volume estimation system.

[0088] The urine volume estimation system 100 according to Modification 2 further includes a posture sensor 312 that detects the posture of the subject and a posture determiner 348 that determines the posture of the subject.

[0089] FIG. 16 is a block diagram of the probe 301 according to Modification 2. The probe 301 further includes a posture sensor 312. The posture sensor 312 is housed in the casing 10 of the probe 301. For example, the posture sensor 312 is disposed on the substrate 15. The posture sensor 312 detects acceleration. For example, the posture sensor 312 is an acceleration sensor that detects the acceleration of each of the three orthogonal axes. An acceleration signal is output from the posture sensor 312.

[0090] The processor 38 of the probe 301 acquires the detection signal of the attitude sensor 312 when transmitting and receiving ultrasonic waves. The processor 38 controls the communicator 36 to transmit the signals from the receiver 32 and the attitude sensor 312 to the outside.

[0091] The arithmetic unit 304 receives and stores the received signals transmitted from the probe 301 (that is, the received signal (received wave) of the ultrasonic sensor 2 received and processed by the receiver 32 and the acceleration signal from the attitude sensor 312). Hereinafter, the acceleration signal received from the probe 301 is also simply referred to as "the acceleration of the attitude sensor 312".

[0092] FIG. 17 is a block diagram showing the functional configuration of the processor 341 according to the second modification. The processor 341 of the arithmetic unit 4 has an attitude determination unit 348 in addition to the indicator 45, the acquirer 46, and the estimator 47.

[0093] The acquirer 46 receives, that is, acquires, the acceleration of the attitude sensor 312 in addition to the received signal of the ultrasonic sensor 2 by communicating with the control device 3. The acquirer 46 stores the received signal and the acceleration in the storage 44 together with the time when the received signal and the acceleration were received (that is, the acquisition time). The storage 44 accumulates the received signal, the acceleration, and the acquisition time.

[0094] The posture determiner 348 determines whether the posture of the subject is an estimable posture for which a second estimation is possible or a difficult-to-estimate posture for which a second estimation is difficult based on the posture detected by the posture sensor 312. This posture determination function is realized by the processor 341 executing the urine volume estimation program 81 stored in the storage 44. The urine volume estimation program 81 has a function of continuously estimating the urine volume in the bladder based on the reflected wave from the bladder received by the ultrasonic sensor 2 that transmits ultrasonic waves into the body of the subject and receives the reflected waves, and a function of determining whether the posture of the subject is a posture in which the urine volume can be estimated or a posture in which the urine volume is difficult to estimate based on the posture of the subject detected by the posture sensor 312, and causes the processor 341 as a computer to realize these functions. More specifically, the posture determiner 348 obtains in which direction gravity acts based on the three-axis acceleration, and estimates the posture of the subject based on the direction in which gravity acts. Then, the posture determiner 348 determines whether the estimated posture is an estimable posture or not.

[0095] Here, the estimable posture is a posture in which the contact state of the probe 301 with the body surface is appropriately maintained. The estimable posture may vary depending on the shape of the probe 301 and the method of attaching the probe 301 to the body surface, etc. There are various modes of the estimable posture. For example, in the standing position or the sitting position, when the rotation angle around the left-right axis (i.e., the tilting angle in the front-back direction) is within a predetermined range and the rotation angle around the front-back axis (i.e., the tilting angle in the left-right direction) is within a predetermined range, the posture determiner 348 determines it as an estimable posture. Specifically, in the standing position or the sitting position, when in a backward-tilted state and with small left and right tilts, it is an estimable posture. In the lying position, when the rotation angle around the midline (the axis passing through the head and the trunk) is within a predetermined range, the posture determiner 348 determines it as an estimable posture. Specifically, in the lying position, the supine position or the prone position is an estimable posture.

[0096] On the other hand, a posture other than the estimable posture is a difficult-to-estimate posture. There are various modes of the difficult-to-estimate posture. For example, as one mode of the difficult-to-estimate posture, there is the lateral lying position. Also, as another mode of the difficult-to-estimate posture, there is the standing position or the sitting position in a forward-tilted state.

[0097] The estimator 47 performs a first estimation when the determination by the posture determination device 348 is a posture that is difficult to estimate, and performs a second estimation when the determination by the posture determination device 348 is a posture that can be estimated. For example, the estimator 47 periodically performs the first estimation at the estimation timing, and when a posture that can be estimated is determined by the posture determination device 348 during that time, the estimator 47 executes the second estimation.

[0098] FIG. 18 is a flowchart of the processing of the control device 3 according to Modification 2. The processing of the control device 3 according to Modification 2 is basically the same as the processing of the basic control device 3.

[0099] Specifically, in step S401, the processor 38 determines whether the measurement conditions are satisfied. The processing in step S401 is the same as that in step S101. The measurement conditions include a first measurement condition and a second measurement condition. The first measurement condition is that a predetermined measurement timing arrives. The second measurement condition is that a measurement command is received from the outside (for example, the arithmetic unit 4). When the measurement timing arrives or the measurement command is received, the processor 38 determines that the measurement conditions are satisfied. Until the measurement conditions are satisfied, the processor 38 repeats step S401.

[0100] When the measurement conditions are satisfied, in step S402, the processor 38 causes the four first ultrasonic sensors 21 and the two second ultrasonic sensors 22 to transmit and receive ultrasonic waves in order while switching the switch 33. The processing in step S402 is the same as that in step S102.

[0101] In addition, in step S403, the processor 38 detects the acceleration of the attitude sensor 312. The processor 38 stores the acceleration signal from the attitude sensor 312 in the memory 39. The processing in step S403 is not included in the processing of the basic control device 3.

[0102] Next, in step S404, the processor 38 transmits the received signals of the first ultrasonic sensors 21, the received signals of the second ultrasonic sensors 22, and the acceleration of the attitude sensor 312 stored in the memory 39 to the arithmetic unit 4 via the communicator 36.

[0103] Thereafter, the processor 38 returns to step S401 and repeats the process from step S401.

[0104] In this way, every time the measurement conditions are satisfied, the processor 38 executes the transmission and reception of ultrasonic waves by all the ultrasonic sensors 2 and the detection of the acceleration of the attitude sensor 312. Specifically, the processor 38 executes the transmission and reception of ultrasonic waves by the ultrasonic sensors 2 and the detection of the acceleration of the attitude sensor 312 not only at periodic measurement timings but also when a measurement command is received.

[0105] Subsequently, the processing of the arithmetic unit 4 according to Modification 2 will be described. FIG. 19 is a flowchart of the processing of the arithmetic unit 4 according to Modification 2.

[0106] In step S501, the estimator 47 determines whether the estimation timing has arrived. The estimation timing repeats at a predetermined estimation period. In this example, the estimation period is the same as the measurement period.

[0107] If the estimation timing has not arrived, the estimator 47 repeats the process of step S501. That is, the estimator 47 waits for the arrival of the estimation timing.

[0108] When the estimation timing has arrived, in step S502, the estimator 47 determines whether the determination by the attitude determiner 348 is an estimable attitude. Specifically, the attitude determiner 348 determines whether the attitude of the subject is an estimable attitude based on the latest acceleration of the attitude sensor 312. Step S502 corresponds to switching between the first estimation and the second estimation.

[0109] When the determination by the posture determination device 348 is not an estimable posture, the estimator 47 executes a first estimation in step S503. The process of step S503 is the same as that of step S203. Note that in the first estimation, the latest reception signal of the ultrasonic sensor 2 is used. The latest reception signal of the ultrasonic sensor 2 is included in the same set as the acceleration of the posture sensor 312 used for the determination of the subject's posture. When the first estimation is completed, the estimator 47 returns to the process of step S501. Step S503 corresponds to executing the first estimation.

[0110] On the other hand, when the determination by the posture determination device 348 is an estimable posture, the estimator 47 executes a second estimation in step S504. The process of step S504 is the same as that of step S206. Note that in the second estimation, the latest reception signal of the ultrasonic sensor 2 is used. The latest reception signal of the ultrasonic sensor 2 is included in the same set as the acceleration of the posture sensor 312 used for the determination of the subject's posture. When the second estimation is completed, the estimator 47 returns to the process of step S501. Step S504 corresponds to executing the second estimation.

[0111] That is, the estimator 47 executes either the first estimation or the second estimation at periodic estimation timings. The posture of the subject is determined based on the acceleration of the posture sensor 312 corresponding to the reception signal of the ultrasonic sensor 2 used for the first estimation or the second estimation. The first estimation is selected when the posture is not an estimable posture, and the second estimation is selected when the posture is an estimable posture.

[0112] In this way, the first estimation for estimating the urine volume based on the detection result of the first ultrasonic sensor 21 and the second estimation for estimating the urine volume based on the detection result of the second ultrasonic sensor 22 are alternately executed. By switching between the first estimation and the second estimation, the urine volume in the bladder can be evaluated from different viewpoints.

[0113] In addition, in the first estimation, the urine volume in the bladder is estimated based on the number of the first ultrasonic sensors 21 that receive the reflected waves from the bladder. On the other hand, in the second estimation, the expansion of the bladder in the transmission direction of the second ultrasonic sensor 22 is obtained from the detection result of the second ultrasonic sensor 22, and the urine volume in the bladder is estimated based on the obtained expansion of the bladder. That is, in the first estimation, it is only necessary to know the presence or absence of the reflected waves from the bladder, and the accuracy such as the reception time of the reflected waves from the bladder may be low. On the other hand, in the second estimation, the expansion of the bladder in the transmission direction of the ultrasonic wave is obtained based on the reception time of the reflected waves from the bladder. Therefore, the estimation accuracy of the urine volume in the second estimation depends on the accuracy such as the reception time of the reflected waves from the bladder. Since the second estimation is performed based on the reflected waves acquired when the posture of the subject is a posture that can be estimated, the estimation accuracy of the urine volume by the second estimation can be improved.

[0114] <Modification Example 3> Subsequently, the urine volume estimation system 100 according to Modification Example 3 will be described. The urine volume estimation system 100 according to Modification Example 3 is different from the above-described basic urine volume estimation system 100 under the condition where the second estimation is executed. The urine volume estimation system 100 according to Modification Example 3 further includes a posture sensor 312 that detects the posture of the subject and a posture determination device 348 that determines the posture of the subject, similar to the urine volume estimation system 100 according to Modification Example 2. However, the arithmetic unit 4 according to Modification Example 3 performs the switching between the first estimation and the second estimation based on the posture of the subject in combination with the switching based on the estimated urine volume.

[0115] FIG. 20 is a flowchart of the processing of the arithmetic unit 4 according to Modification Example 3. The flowchart of the processing of the arithmetic unit 4 according to Modification Example 3 is basically the same as the flowchart of the processing of the arithmetic unit 4 according to Modification Example 1. However, in the flowchart of FIG. 20, step S605 is inserted between step S302 and step S304 in the flowchart of FIG. 15.

[0116] Specifically, when it is determined in step S302 that the most recent estimated urine volume is equal to or greater than the threshold α, the estimator 47 determines in step S605 whether the determination by the posture determiner 348 is a posture that can be estimated. The posture determiner 348 determines whether the posture of the subject is a posture that can be estimated based on the latest acceleration of the posture sensor 312. Step S605 corresponds to switching between the first estimation and the second estimation.

[0117] If the determination by the posture determiner 348 is not a posture that can be estimated, the estimator 47 performs the first estimation in step S303. On the other hand, if the determination by the posture determiner 348 is a posture that can be estimated, the estimator 47 performs the second estimation in step S304.

[0118] As described above, in the third modification, urine volume estimation by the first estimation or the second estimation is periodically performed at the estimation timing. The first estimation and the second estimation are selected according to the urine volume and the posture. Specifically, the first estimation is performed when the urine volume is less than the threshold α or when the subject is not in a posture that can be estimated, and the second estimation is performed when the urine volume is equal to or greater than the threshold α and the subject is in a posture that can be estimated. The higher the urine volume, the higher the urgency of urination. However, the second estimation is not selected only because the urine volume is high. The second estimation is selected when the urine volume is high and the posture of the subject is a posture that can be estimated. If the posture is not a posture that can be estimated even though the urine volume is high, the first estimation is selected. That is, the second estimation is selected when both the necessity and the feasibility of highly accurate urine volume estimation are satisfied. When the urine volume is low, the necessity for highly accurate urine volume estimation is small, so the first estimation is selected regardless of the posture. Thereby, when the urine volume is relatively low, the urine volume is monitored while reducing the calculation load.

[0119] 《Other Embodiments》 As described above, the embodiments have been described as examples of the technology disclosed in the present application. However, the technology in the present disclosure is not limited thereto, and is also applicable to embodiments in which appropriate changes, replacements, additions, omissions, etc. are made. Further, it is also possible to combine the respective components described in the above embodiments to form a new embodiment. Further, among the components described in the accompanying drawings and the detailed description, there may be included not only the components essential for solving the problems, but also the components not essential for solving the problems for exemplifying the technology. Therefore, just because those non-essential components are described in the accompanying drawings and the detailed description, it should not be immediately determined that those non-essential components are essential.

[0120] The above-described embodiment may have the following configuration.

[0121] The installation location of the probe 1 on the body surface can be arbitrarily set. Also, the mounting method of the probe 1 is not limited to the above method. For example, the contact surface 11 may be formed of an adhesive sticking surface, and the contact surface 11 may be attached to the abdomen of the subject. Alternatively, a tape may be stuck to the body surface from above the probe 1.

[0122] The number of the plurality of ultrasonic sensors 2 is not limited to six. The number of the first ultrasonic sensors 21 is not limited to four, and may be three or less or five or more. The number of the second ultrasonic sensors 22 is not limited to three, and may be two or less or four or more. One of the first ultrasonic sensors 21 does not have to also serve as the second ultrasonic sensor 22.

[0123] The arrangement of the plurality of ultrasonic sensors 2 is not limited to the above-described arrangement. It is sufficient that the transmission directions of the ultrasonic waves of the plurality of first ultrasonic sensors 21 are shifted at least in the first direction X. For example, the transmission directions of the ultrasonic waves of the plurality of first ultrasonic sensors 21 may be further shifted in a direction different from the first direction X. That is, the plurality of first ultrasonic sensors 21 may be offset from each other also in the second direction Y, that is, may be arranged in a staggered pattern. If the arrangement of the plurality of first ultrasonic sensors 21 is shifted in the first direction X, the elevation angles of the plurality of first ultrasonic sensors 21 may be parallel to each other. Note that the same applies to the second ultrasonic sensor 22. The first direction X and the second direction Y do not have to be orthogonal to each other.

[0124] Also, the casing 10 is not limited to the above-described configuration. For example, a protrusion may be provided on the contact surface 11 of the casing 10. The ultrasonic sensor 2 may be built into the protrusion. In this case, the protrusion improves the adhesion between the skin (body surface) of the portion of the casing 10 in which the ultrasonic sensor 2 is built and promotes the incidence of ultrasonic waves into the human body. Thereby, the detection ability of the bladder is enhanced. The casing 10 may be generally formed in a disk shape.

[0125] The control device 3 is integrated with the probe 1, that is, is housed in the casing 10, but is not limited thereto. The control device 3 may be formed separately from the probe 1. In that case, the control device 3 can be connected to the probe 1 by wire or wirelessly. The control device 3 may be divided, a part of the control device 3 may be housed inside the probe 1, and the remaining part of the control device 3 may be arranged outside the probe 1.

[0126] The configuration of the control device 3 is not limited to the above-described configuration. For example, although the transmitter 31 inputs a pulse signal as a drive signal to the probe 1, the drive signal is not limited to a pulse signal. The drive signal may be a burst wave or the like instead of a pulse wave. Also, the notifier 35 is not limited to an LED lamp, and may be a display, an alarm, or a vibrator.

[0127] The measurement conditions for the transmission and reception of ultrasonic waves in probe 1 are not limited to the aforementioned conditions. For example, the arithmetic unit 4 may monitor periodic measurement timings, and when a measurement timing arrives, the arithmetic unit 4 may send a measurement command to probe 1. In that case, the control device 3 receiving the measurement command becomes the measurement condition. That is, the arithmetic unit 4 may manage the timings of ultrasonic wave transmission and reception, and the control device 3 may passively execute ultrasonic wave transmission and reception.

[0128] The measurement conditions of probe 1 may include measurement conditions for the first estimation and measurement conditions for the second estimation. When the measurement conditions for the first estimation are satisfied, probe 1 may transmit and receive ultrasonic waves only to the ultrasonic sensor 2 used for the first estimation. When the measurement conditions for the second estimation are satisfied, probe 1 may transmit and receive ultrasonic waves only to the ultrasonic sensor 2 used for the second estimation. For example, when the measurement conditions for the first estimation are satisfied, probe 1 may transmit and receive ultrasonic waves only to the first ultrasonic sensor 21, and it may not be necessary to transmit and receive ultrasonic waves to the second ultrasonic sensor 22. When the measurement conditions for the second estimation are satisfied, probe 1 may transmit and receive ultrasonic waves to both the first ultrasonic sensor 21 and the second ultrasonic sensor 22.

[0129] The communication between the arithmetic unit 4 and probe 1 may be wired instead of wireless. The communication between the arithmetic unit 4 and an external device such as server 51 is not essential.

[0130] The arithmetic unit 4 does not have to be a smart device such as a smartphone. The arithmetic unit 4 may be a personal computer or a server or the like. In that case, probe 1 may be connected to the Internet via relay machine 52 and communicate with the arithmetic unit 4 via the Internet. Furthermore, the arithmetic unit 4 may be able to communicate with a user terminal such as a smart device. The user may perform an execution operation such as the second estimation via the user terminal, and an execution input may be transmitted from the user terminal to the arithmetic unit 4.

[0131] The estimation methods of the first estimation and the second estimation are not limited to the aforementioned methods. The first estimation and the second estimation only need to evaluate the expansion of the bladder in different directions. In the second estimation, the urine volume may be estimated using the received signal of the second ultrasonic sensor 22 without using the received signal of the first ultrasonic sensor 21. For example, in the second estimation, similar to the first estimation, the urine level may be estimated according to the number of the second ultrasonic sensors 22 for detecting the bladder. In the second estimation, based on the transmission directions of the ultrasonic waves of the plurality of second ultrasonic sensors 22 and the positions of the walls of the bladder at a plurality of locations in the cross section extending in the second direction Y, that is, based on the cross-sectional shape of one part of the bladder, the capacity of the bladder may be roughly calculated. In estimating the capacity of the bladder from the cross section of the bladder, the cross section of the bladder may be approximated to a shape other than an ellipse. For example, the cross-sectional shape of the bladder may be obtained by spline interpolation of the positions of the walls of the bladder at a plurality of locations obtained based on the received signal.

[0132] In addition, it is preferable that the second estimation adopts an estimation method with higher estimation accuracy than the first estimation. For example, in the first estimation, the urine level may be estimated according to the number of the first ultrasonic sensors 21 for detecting the bladder, and in the second estimation, the urine level may be estimated according to the numbers of the first ultrasonic sensors 21 and the second ultrasonic sensors 22 for detecting the bladder. Alternatively, in the first estimation, the shape of the bladder, that is, the capacity may be roughly calculated based on the transmission directions of the ultrasonic waves of the plurality of first ultrasonic sensors 21 and the positions of the walls of the bladder at a plurality of locations in the cross section extending in the first direction X. That is, in the first estimation, the capacity of the bladder is calculated based on the transmission directions of the ultrasonic waves of the plurality of first ultrasonic sensors 21 and the positions of the walls of the bladder at a plurality of locations in the cross section extending in the first direction X, and in the second estimation, the capacity of the bladder may be calculated based on the positions of the walls of the bladder at a plurality of locations in the cross section extending in the transmission directions of the ultrasonic waves of the plurality of first ultrasonic sensors 21 and the first direction X, and the positions of the walls of the bladder at a plurality of locations in the cross section extending in the transmission directions of the ultrasonic waves of the plurality of second ultrasonic sensors 22 and the second direction Y.

[0133] The posture sensor 312 is not limited to an acceleration sensor that detects orthogonal three-axis acceleration. The posture sensor 312 may be a gyro sensor. Further, the posture sensor 312 may have the function of the posture determiner 348. For example, the posture sensor 312 may have a threshold value for determining the posture inside and output a signal according to the determination result of the posture. The posture sensor 312 may be separated from the probe 1. For example, the posture sensor 312 may be attached to the subject separately from the probe 1 and be communicable with the arithmetic unit 4.

[0134] The conditions under which the first estimation or the second estimation is executed in the arithmetic unit 4 can be arbitrarily set. For example, in the process of the basic arithmetic unit 4 in FIG. 14, the first estimation may be executed when there is an execution input for the first estimation instead of the arrival of the estimation timing. For example, an execution button for the first estimation and an execution button for the second estimation may be displayed on the application screen of the arithmetic unit 4. When the execution button for the first estimation is operated, the arithmetic unit 4 may execute the first estimation, and when the execution button for the second estimation is operated, the arithmetic unit 4 may execute the second estimation. When there is an execution input, a measurement command is output to the probe 1 as in step S204. Also, in step S301 or S501 in other flowcharts, it may be a determination as to whether there is an execution input for urine volume estimation instead of the arrival of the estimation timing. When there is an execution input, a measurement command is output to the probe 1 as in step S204.

[0135] The above-described flowchart is merely an example. The steps in the flowchart may be appropriately changed, replaced, added, omitted, etc. Also, the order of the steps in the flowchart may be changed, or serial processes may be processed in parallel.

[0136] The functions realized by the components described in this specification may be implemented in circuitry or processing circuitry including a general-purpose processor, a specific-purpose processor, an integrated circuit, ASICs (Application Specific Integrated Circuits), a CPU (a Central Processing Unit), conventional circuits, and / or combinations thereof, programmed to realize the described functions. The processor includes transistors and other circuits and is regarded as circuitry or processing circuitry. The processor may be a programmed processor that executes a program stored in a memory.

[0137] In this specification, circuitry, units, and means are hardware programmed to realize the described functions or hardware that executes the functions. The hardware may be any hardware disclosed in this specification or any hardware known to be programmed or execute to realize the described functions.

[0138] When the hardware is a processor regarded as being of the circuitry type, the circuit, means, or unit is a combination of the hardware and the software used to configure the hardware and / or the processor.

[0139] [Aspect] The above embodiments are specific examples of the following aspects.

[0140] (Aspect 1) The urine volume estimation system 100 includes an ultrasonic sensor 2 that transmits ultrasonic waves into the body of a subject and receives reflected waves, and an estimator 47 that estimates the urine volume in the bladder based on the detection results of the ultrasonic sensor 2. The ultrasonic sensor 2 includes a plurality of first ultrasonic sensors 21 whose ultrasonic wave transmission directions are offset in a predetermined first direction X, and a plurality of second ultrasonic sensors 22 whose ultrasonic wave transmission directions are offset in a second direction Y different from the first direction X. The estimator 47 switches between a first estimation that estimates the urine volume in the bladder based on the detection results of the first ultrasonic sensors 21 and a second estimation that estimates the urine volume in the bladder based on the detection results of the second ultrasonic sensors 22.

[0141] According to this configuration, the first ultrasonic sensors 21 receive reflected waves from different portions of the bladder in the first direction X. On the other hand, the second ultrasonic sensors 22 receive reflected waves from different portions of the bladder in the second direction Y. The first estimation can evaluate the expansion of the bladder in the first direction X. The second estimation can evaluate the expansion of the bladder in the second direction Y. Therefore, by switching between the first estimation and the second estimation, the expansion of the bladder in different directions can be evaluated.

[0142] (Aspect 2) In the urine volume estimation system 100 according to Aspect 1, in the second estimation, the estimator 47 estimates the urine volume in the bladder based on the detection results of both the first ultrasonic sensors 21 and the second ultrasonic sensors 22.

[0143] According to this configuration, the second estimation can evaluate the expansion of the bladder in both the first direction X and the second direction Y.

[0144] (Aspect 3) In the urine volume estimation system 100 according to Aspect 1 or Aspect 2, at least one of the plurality of first ultrasonic sensors 21 also serves as the second ultrasonic sensors 22.

[0145] According to this configuration, since at least one of the first ultrasonic sensors 21 also serves as the second ultrasonic sensors 22, the number of sensors can be reduced.

[0146] (Aspect 4) In the urine volume estimation system 100 according to any one of Aspects 1 to 3, in the first estimation, the estimator 47 estimates the urine volume in the bladder based on the number of the first ultrasonic sensors 21 that receive the reflected waves from the bladder, and in the second estimation, obtains the expansion of the bladder in the transmission direction of the ultrasonic waves from each of the second ultrasonic sensors 22 from the detection results of the second ultrasonic sensors 22, and estimates the urine volume in the bladder based on the obtained expansion of the bladder.

[0147] According to this configuration, in the first estimation, since the urine volume in the bladder is estimated based on the number of the first ultrasonic sensors 21 that receive the reflected waves from the bladder, the urine volume in the bladder can be estimated by a relatively simple calculation. In the second estimation, since the urine volume in the bladder is estimated based on the expansion of the bladder in the transmission direction of the ultrasonic waves of each second ultrasonic sensor 22, the urine volume in the bladder can be estimated with higher accuracy than in the first estimation. That is, the estimator 47 can switch between the estimation of the urine volume by a simple calculation and the estimation of the urine volume with high accuracy.

[0148] (Aspect 5) In the urine volume estimation system 100 according to any one of Aspects 1 to 4, the estimator 47 normally performs the first estimation and switches the first estimation to the second estimation when receiving an execution command for the second estimation.

[0149] According to this configuration, the estimator 47 basically performs the first estimation. Then, when the estimator 47 receives an execution command for the second estimation, it performs the second estimation. For example, an execution command is input from the indicator 45 to the estimator 47 in response to an input operation by the user. Therefore, normally the first estimation is executed, and the second estimation is executed according to the user's intention. Alternatively, an execution command may be input to the estimator 47 due to a factor other than the input operation by the user. For example, when a predetermined condition is satisfied, an execution command may be input from the indicator 45 to the estimator 47. The predetermined condition may be that a predetermined time is reached. In this case, the second estimation is executed at a predetermined time every day. Alternatively, the predetermined condition may be that the estimated urine volume by the first estimation reaches a predetermined value, or the posture of the subject becomes a predetermined posture.

[0150] (Aspect 6) In the urine volume estimation system 100 according to any one of Aspects 1 to 5, when the urine volume estimated based on the first estimation reaches a predetermined threshold α, the estimator 47 switches the first estimation to the second estimation.

[0151] According to this configuration, when the estimated urine volume is less than the threshold α, the first estimation is executed, and when the estimated urine volume is equal to or greater than the threshold α, the second estimation is executed. As a result, the first estimation and the second estimation are switched according to the urine volume. For example, when the estimation accuracy of the second estimation is higher than that of the first estimation, a urine volume estimation with high accuracy is executed when the estimated urine volume is relatively large. Thereby, a urine volume estimation with high accuracy is executed when the urgency of urination is high.

[0152] (Aspect 7) In the urine volume estimation system 100 according to any one of Aspects 1 to 6, a posture sensor 312 that detects the posture of the subject, and a posture determiner 348 that determines whether the posture of the subject is a posture in which the second estimation is possible (estimable posture) or a posture in which the second estimation is difficult (difficult estimation posture) based on the posture detected by the posture sensor 312 are further provided. The estimator 47 performs the first estimation when the determination by the posture determiner 348 is the difficult estimation posture, and performs the second estimation when the determination by the posture determiner 348 is the estimable posture.

[0153] According to this configuration, the posture sensor 312 and the posture determiner 348 determine whether the posture of the subject is an estimable posture or a difficult estimation posture. Then, when the posture of the subject is an estimable posture, the second estimation is executed, and when the posture of the subject is a difficult estimation posture, the first estimation is executed. The urine volume estimation is performed by receiving the reflected wave of the ultrasonic wave transmitted into the subject's body. Therefore, there are a posture suitable for the transmission and reception of ultrasonic waves and a posture that is not suitable for the subject's posture. By executing the second estimation in the case of a posture suitable for the second estimation, the accuracy of the second estimation can be improved.

[0154] (Aspect 8) The urine volume estimation method includes performing a first estimation of estimating the urine volume in the bladder based on the reflected wave from the bladder of the ultrasonic wave transmitted into the body of the subject using a plurality of first ultrasonic sensors 21 whose transmission directions of the ultrasonic wave are shifted in a predetermined first direction X, performing a second estimation of estimating the urine volume in the bladder based on the reflected wave from the bladder of the ultrasonic wave transmitted into the body of the subject using a plurality of second ultrasonic sensors whose transmission directions of the ultrasonic wave are shifted in a second direction Y different from the first direction X, and switching between the first estimation and the second estimation.

[0155] According to this configuration, the first ultrasonic sensor 21 receives the reflected waves from different portions of the bladder in the first direction X. On the other hand, the second ultrasonic sensor 22 receives the reflected waves from different portions of the bladder in the second direction Y. The first estimation can evaluate the expansion of the bladder in the first direction X. The second estimation can evaluate the expansion of the bladder in the second direction Y. Therefore, by switching between the first estimation and the second estimation, the expansion of the bladder in different directions can be evaluated.

[0156] (Aspect 9) The urine volume estimation program 81 causes a computer to realize a function of performing a first estimation of estimating the urine volume in the bladder based on the reflected wave from the bladder of the ultrasonic wave transmitted into the body of the subject using a plurality of first ultrasonic sensors 21 whose transmission directions of the ultrasonic wave are shifted in a predetermined first direction X, a function of performing a second estimation of estimating the urine volume in the bladder based on the reflected wave from the bladder of the ultrasonic wave transmitted into the body of the subject using a plurality of second ultrasonic sensors 22 whose transmission directions of the ultrasonic wave are shifted in a second direction Y different from the first direction X, and a function of switching between the first estimation and the second estimation.

[0157] According to this configuration, the first ultrasonic sensor 21 receives the reflected waves from different portions of the bladder in the first direction X. On the other hand, the second ultrasonic sensor 22 receives the reflected waves from different portions of the bladder in the second direction Y. The first estimation can evaluate the expansion of the bladder in the first direction X. The second estimation can evaluate the expansion of the bladder in the second direction Y. Therefore, by switching between the first estimation and the second estimation, the expansion of the bladder in different directions can be evaluated.

Description of Symbols

[0158] 100 Urine volume estimation system 2 Ultrasonic sensor 21 First ultrasonic sensor 22 Second ultrasonic sensor 312 Posture sensor 47 Estimator 348 Posture determiner X First direction Y Second direction

Claims

1. An ultrasonic sensor that transmits ultrasonic waves into the body of a subject and receives reflected waves, and an estimator that estimates the urine volume in the bladder based on the detection result of the ultrasonic sensor, and the ultrasonic sensor includes a plurality of first ultrasonic sensors whose ultrasonic wave transmission directions are shifted in a predetermined first direction, and a plurality of second ultrasonic sensors whose ultrasonic wave transmission directions are shifted in a second direction different from the first direction, and the estimator is a urine volume estimation system that switches between a first estimation of estimating the urine volume in the bladder based on the detection result of the first ultrasonic sensor and a second estimation of estimating the urine volume in the bladder based on the detection result of the second ultrasonic sensor.

2. In the urine volume estimation system according to claim 1, in the second estimation, the estimator is a urine volume estimation system that estimates the urine volume in the bladder based on the detection results of both the first ultrasonic sensor and the second ultrasonic sensor.

3. In the urine volume estimation system according to claim 1, at least one of the plurality of first ultrasonic sensors also serves as the second ultrasonic sensor.

4. In the urine volume estimation system according to any one of claims 1 to 3, the estimator estimates the urine volume in the bladder based on the number of the first ultrasonic sensors that receive the reflected waves from the bladder in the first estimation, and in the second estimation, obtains the expansion of the bladder in the transmission direction of the ultrasonic waves from each of the second ultrasonic sensors from the detection result of the second ultrasonic sensor, and estimates the urine volume in the bladder based on the obtained expansion of the bladder.

5. In the urine volume estimation system according to claim 1, the estimator usually performs the first estimation and switches the first estimation to the second estimation when receiving an execution command for the second estimation.

6. In the urine volume estimation system according to claim 1, the estimator switches the first estimation to the second estimation when the urine volume estimated based on the first estimation reaches a predetermined threshold value.

7. In the urine volume estimation system according to claim 1, a posture sensor that detects the posture of the subject, and a posture determination device that determines based on the posture detected by the posture sensor whether the posture of the subject is an estimable posture in which the second estimation is possible or an estimation-difficult posture in which the second estimation is difficult. ​ ​ ​ ​ The estimator is a urine volume estimation system that performs the first estimation when the determination by the posture determination device is the posture difficult to estimate, and performs the second estimation when the determination by the posture determination device is the posture that can be estimated.

8. Performing a first estimation of estimating the urine volume in the bladder based on the reflected wave from the bladder of the ultrasonic wave transmitted into the body of the subject using a plurality of first ultrasonic sensors whose ultrasonic transmission directions are shifted in a predetermined first direction; Performing a second estimation of estimating the urine volume in the bladder based on the reflected wave from the bladder of the ultrasonic wave transmitted into the body of the subject using a plurality of second ultrasonic sensors whose ultrasonic transmission directions are shifted in a second direction different from the first direction; A urine volume estimation method including switching between the first estimation and the second estimation.

9. A function of performing a first estimation of estimating the urine volume in the bladder based on the reflected wave from the bladder of the ultrasonic wave transmitted into the body of the subject using a plurality of first ultrasonic sensors whose ultrasonic transmission directions are shifted in a predetermined first direction; A function of performing a second estimation of estimating the urine volume in the bladder based on the reflected wave from the bladder of the ultrasonic wave transmitted into the body of the subject using a plurality of second ultrasonic sensors whose ultrasonic transmission directions are shifted in a second direction different from the first direction; A urine volume estimation program that causes a computer to realize a function of switching between the first estimation and the second estimation.

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