Residual tensile stresses can be mitigated through methods and systems provided by the present invention. The engine and the first and second rotating electrical machines are connected to different rotational elements out of rotational elements of the first and second differential mechanisms. The apparatus may further include a sensor. A filling element is located on the door and has a curved outward portion in the shape of a truncated cone. Thereby, it is possible to detect the pupil accurately even if a part of the pupil is covered.