Wheel and vehicle

A wheel comprising:

• an outer ring that rotates about a wheel rotational axis;
• an arm drive shaft that includes a rotational axis coaxial with the wheel rotational axis and that is inserted into a hole formed at a center of the outer ring;
• an arm drive gear that is provided at the arm drive shaft and that rotates independently from the outer ring about the wheel rotational axis;
• an arm capable of rotating about an arm rotational axis fixed to the outer ring, the arm being configured to partially protrude outside an outer peripheral surface of the outer ring in a radial direction as the arm drive gear rotates relative to the outer ring in one direction and to be housed inside the outer peripheral surface of the outer ring in the radial direction as the arm drive gear rotates relative to the outer ring in another direction opposite to the one direction;
• an arm actuator that drives the arm drive gear through the arm drive shaft;
• an outer ring gear that rotates integrally with the outer ring about the wheel rotational axis;
• an outer ring drive gear that meshes with the outer ring gear and that rotates about an outer ring drive rotational axis parallel to the wheel rotational axis;
• and
• an outer ring actuator that drives independently from the arm actuator and that drives the outer ring drive gear,
• wherein in a state where the arm is housed inside the outer peripheral surface of the outer ring in the radial direction, when the arm actuator and the outer ring actuator are controlled such that the arm drive gear rotates in the one direction and a rotation of the outer ring stops, the arm partially protrudes outside the outer peripheral surface of the outer ring in the radial direction,
• in a state where the arm partially protrudes outside the outer peripheral surface of the outer ring in the radial direction, when the arm actuator and the outer ring actuator are controlled such that a rotation of the arm drive gear stops and the outer ring rotates in the one direction, the arm is housed inside the outer peripheral surface of the outer ring in the radial direction, and
• when a rotational direction and a rotational speed of an output shaft of each of the arm actuator and the outer ring actuator are controlled such that the arm drive gear and the outer ring rotate at a same rotational speed in a same rotational direction, the state where the arm protrudes or the state where the arm is housed is maintained.