Estimation of load torque for motorized seat belt system with reduced-order observer

This paper describes design and verification of reduced-order state observer to estimate state information such as angular velocity and load torque of a dc-motor for generating tension of the motorized seat belt (MSB) system. The MSB system provides functions to protect passengers and improve passenger´s convenience. To generate the exact tension to passenger, angular velocity and load torque should be measured or estimated. State information for MSB operations can be estimated without sensors by use of the reduced-order observer. The reduced-order observer is designed by the developed state space model. Designed reduced-order observer and retraction control algorithm are verified by experiments on the test bench.