Method and device for operating a seatbelt tensioner in a vehicle

Abstract

The invention relates to a method for operating a belt tensioner of a seat belt (101, 113, 114) in a vehicle (100), wherein: - in a belt tensioning operation, the belt tensioner is controlled such that a successive tightening of the seat belt (101, 113, 114) is carried out by means of it by generating different tightening forces (F); - in parallel to the belt tensioning, images (B1 to Bn) of at least one eye (105) of a vehicle occupant (107, 111, 112) are acquired successively in an image acquisition system; - in parallel to the image acquisition, a pupil size (G) of the at least one eye (105) is determined in each of the images (B1 to Bn) based on an image evaluation; - based on the image evaluation, a pupil size (G) of the at least one eye (105) is determined from the different pupil sizes (G) of the pupil (108) in the images (B1 to Bn) using a known respiratory-pupil phase response. Bn) a respiratory amplitude (A) and / or a respiratory rate (f) will be determined,- a gradient (grad A) of the respiratory amplitude (A) and / or a gradient (grad f) of the respiratory rate (f) is determined and - then, if a change in the gradient (grad A) of the respiratory amplitude (A) and / or a change in the gradient (grad f) of the respiratory rate (f) over time (t) exceeds a predetermined threshold, the belt tensioner is controlled such that a tension force (F) set immediately before the threshold was exceeded is applied.

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