A positioning assembly is provided with an endless loop conveyor belt for transporting an object and a first and second roller (12) arranged inside the endless loop. A first mounting part connected to a first end of the first roller (12) and a second mounting part connected to a second end of the first roller (12) are independently movable in a length direction of the conveyor with respect to the frame (15). An actuator system is provided which includes a first lateral actuator (61) arranged to move at least a part of the first roller (12) in a direction parallel to the rotational axes (106) of the first roller (12). The first roller (12) is longitudinally divided into at least two longitudinal segments. The first lateral actuator (61) moves at least one of the longitudinal segments parallel to the rotational axis (106) of the first roller (12).