Determination system, determination method, determination device, and determination program that determine when a person starts a get-up motion

A determination system for determining a state of a subject person including a person requiring care, the determination system comprising:

• a detection device including a detection section that includes a piezoelectric sensor formed in a sheet shape, the detection section detecting a wave motion generated by the subject person and outputting an electrical signal based on the detected wave motion;
• and
• a determination device including a processor and a memory, the determination device being configured to receive as input the electrical signal, wherein
• the detection section is placed on or under a mattress on a bed used by the subject person, and
• the determination device compares a signal value of the electrical signal that is output from the detection section to a predetermined upper limit threshold value to determine if the signal value is equal to or higher than the predetermined upper limit threshold value and to a predetermined lower limit threshold value to determine if the signal value is equal to or lower than the predetermined lower limit threshold value, and after determining that the subject person is in a lying position based on the signal value, determines that the subject person starts a get-up motion in which a body position of the subject person moves from the lying position to a sitting position when the signal value satisfies a state determination condition that a period of time when the signal value is not less than the predetermined upper limit threshold value or not more than the predetermined lower limit threshold value exceeds a predetermined time threshold value, from a state in which it is determined that the subject person is in the lying position.