There were no differences found for the PPS. This indicates that the presence of the subsystem did
not influence the likelihood of passenger presence. The PPS did directly influence the speed
management and excessive maneuver subsystem thresholds by lowering them when three passengers
were present in the vehicle. In a few cases, parents and teens noted that the detection of passengers
needs further refinement as heavy objects (e.g., a heavy backpack) placed on the seat would give a
false indication of an unbelted occupant. There is a general need to increase the reliability of the
detection system so that trust and satisfaction can be maintained for participants.
Recommendations: The PPS is a support function for the seat belt detection and driving behavior
feedback. It is recommended that this subsystem be retained as part of the STC due to the fact that
the PPS complements allied STC subsystems (e.g., seat belt detection and excessive maneuver). The
central recommendation is to improve detection accuracy such that false alarms are reduced. This
facilitates the functionality of allied subsystems and would improve driver acceptance.