Monitoring system, monitoring method, and monitoring program

A monitoring system comprising:

• a sensor terminal device configured to output information on an activity of a user which is measured by a sensor worn by the user, the information of the user includes an acceleration of the user;
• a relay terminal device configured to receive the information on the activity of the user which is output from the sensor terminal device and output the received information on the activity of the user;
• an external terminal device configured to receive the information on the activity of the user which is output from the sensor terminal device or the relay terminal device and cause a storage device to store the received activity information;
• and
• an imaging terminal device configured to start capturing an image of the user in accordance with an instruction, record imaging data, and transmit the imaging data to the external terminal device,
• wherein at least any of the sensor terminal device, the relay terminal device, and the external terminal device includes
• a sensor data acquisition device configured to acquire the information on the activity of the user,
• a data analyzer configured to analyze the acquired information on the activity of the user and detect occurrence of an abnormality in the activity of the user, wherein an abnormality the data analyzer is configured to detect is a change in posture of the user before a fall, wherein the data analyzer includes:
• a posture calculator configured to calculate a posture of the user from the acceleration of the user by calculating a first inclination angle (θ) of a Z-axis of an acceleration sensor worn by the user with respect to a vertical direction and a second inclination angle (φ) of an X-axis of the acceleration sensor with respect to the vertical direction,
• a body motion calculator configured to calculate body motion of the user from the acceleration of the user,
• a fall predictor configured to predict an occurrence of a fall based on a combination of the calculated posture and the calculated body motion of the user, wherein the change in posture before a fall is detected based on the prediction by the fall predictor, and
• a first determination device configured to determine whether the calculated posture transitions from a first posture to a second posture, wherein the first posture is a supine posture and the second posture is an upright posture;
• the supine posture is determined when either:
• (a) 130°≤φ≤230° and −40°≤θ<30°, or (b) 130°≤φ≤230° and 140°<θ<220° and the upright posture is determined when 30°≤0<140°,
• an imaging controller configured to instruct the imaging terminal device to start capturing an image of the user and record imaging data in a case where the occurrence of the abnormality is detected by the data analyzer, wherein, in response to the detection of a change in posture before a fall, the imaging controller is configured to instruct the imaging terminal device to start capturing an image of the user before the user falls,
• an imaging data acquisition device configured to acquire the imaging data recorded by the imaging terminal device,
• a data storage device configured to store the imaging data acquired by the imaging data acquisition device, and
• an output device configured to output the imaging data.

A method comprising:

• acquiring information on an activity of a user, wherein the information on the activity of the user includes an acceleration of the user;
• analyzing the acquired information on the activity of the user and detecting occurrence of an abnormality in the activity of the user, wherein analyzing the acquired information further comprises:
• calculating a posture of the user by determining inclination angles of the user's upper body from the acceleration of the user;
• calculating body motion of the user by:
• determining a norm of the acceleration values over a predetermined time period, and applying a filter to the norm of the acceleration values to obtain a filtered body motion value;
• determining whether the calculated posture transitions from a first posture to a second posture within a first time period;
• determining whether the filtered body motion value exceeds a threshold within a second time period following the posture transition;
• determining that the abnormality has occurred when the posture transition is detected followed by the filtered body motion value exceeding the threshold within the second time period;
• instructing an imaging terminal device that captures an image of the activity of the user to start capturing an image of the user and record imaging data in a case where the occurrence of the abnormality is detected;
• acquiring the imaging data recorded by the imaging terminal device;
• storing the acquired imaging data in a data storage device;
• and
• outputting the imaging data, wherein the posture of the user comprises:
• calculating a first inclination angle (θ) of a Z-axis of an acceleration sensor worn by the user with respect to a vertical direction and calculating a second inclination angle (φ) of an X-axis of the acceleration sensor with respect to the vertical direction, wherein the first posture is a supine posture and the second posture is an upright posture;
• the supine posture is determined when either:
• (a) 130°≤φ≤230° and −40°≤θ<30°, or (b) 130°≤φ≤230° and 140°<θ<220° and the upright posture is determined when 30°≤0<140°.