| 摘要 |
A seat belt retractor has an electric motor 10 for retracting and protracting the seat belt. When protraction of the seat belt is detected, an MPU 14 controls the motor 10 to protract the seat belt. The MPU 14 may also control retraction of the seat belt to a predetermined limit and then subsequently protract the seat belt for a predetermined time period for greater occupant comfort. Retraction and protraction of the seat belt may be made dependent on detection of rough road conditions, dozing of the driver, door opening and closing, travelling speed and an impending collision. In a further embodiment activation of an air bag is based on the speed of protraction of the seat belt. The voltage across, and current through, the motor 10 can also be monitored for control and diagnostic purposes. |
