Adjustment assembly for a vehicle with an ultrasonic system and method for obstacle detection

An adjustment assembly for use in a vehicle, the adjustment assembly comprising:

• an adjustable part configured to be adjusted along an adjustment path between a completely closed position and a maximally open position wherein when the adjustable part is in the completely closed position, the adjustable part closes a body opening and when the adjustable part is in the maximally open position with respect to the vehicle the body opening is accessible;
• and
• an ultrasonic system configured to detect an obstacle in the adjustment path and including,
• at least one ultrasonic transmitter configured to emit ultrasonic waves,
• at least one ultrasonic receiver non-visibly provided in a region of a through opening defined by the adjustable part, wherein the at least one ultrasonic receiver is configured to directly receive an ultrasonic wave, emitted by the at least one ultrasonic transmitter and reflected by an obstacle disposed in the adjustment path of the adjustable part, without previously coupling into a component of the adjustable part.