Coarse to fine movement detection in vehicles

A non-transitory recording medium having a computer program stored thereon which when run causes a computer to determine the presence of an occupant, by performing the steps comprising:

• receiving a first signal from a first sensor positioned within a seating area of a seat and having a corresponding sensitive zone passing through the seating area vertically, the first sensor being adapted to sense coarse movements adjacent to and farther from the sensor;
• determining whether the first signal includes a value greater than a coarse motion threshold;
• receiving a second signal from a second sensor positioned within a back rest area of the seat and having a corresponding sensitive zone passing through a chest area of an occupant horizontally, the second sensor being adapted to capture both coarse and finer movements, such as breathing and heartbeats;
• determining whether the second signal includes a value greater than a coarse motion threshold;
• if it is determined that either the first signal or the second signal is greater than the coarse motion threshold, indicating that an occupant is present;
• if it is determined that neither the first signal nor the second signal is greater than the coarse motion threshold, then determining whether the second signal includes a value that is greater than the fine motion threshold, further comprising the steps of:
• performing a spectral analysis on the second signal;
• determining whether there is a dominant response between 0.8 and 3 Hz;
• if it is determined that there is a dominant response between 0.8 and 3 Hz, thus indicating the presence of a heartbeat, indicate that an occupant is present;
• if it is determined that there is no dominant response between 0.8 and 3 Hz, determining whether there is a dominant response between 0.2 to 0.5 Hz;
• if it is determined that there is a dominant response between 0.2 and 0.5 Hz, thus indicating the presence of breathing, indicate that an occupant is present;
• and
• If there is no dominant response between 0.2 and 0.5 Hz or between 0.8 and 3 Hz, indicate that no occupant is present;
• if it is determined that the second signal includes a value greater than the fine motion threshold, indicating that an occupant is present;
• and
• if it is determined that the second signal does not include a value that is greater than the fine motion threshold, indicate that no occupant is present.