Motion assistance apparatus

1. A motion assistance apparatus, comprising:

a shank frame configured to support a shank of a user;

a thigh frame configured to rotate relative to the shank frame, and to support a thigh of the user, the thigh frame including a protrusion;

a driving frame configured to assist a motion of a hip joint of the user by transmitting a power from a hip joint driver to the shank frame, the driving frame including an elongated guide configured to guide movement of the protrusion such that a distance the thigh frame is movable within the elongated guide is set to allow the protrusion to move freely within the guide during a sit-to-stand motion of the user;

a thigh support connected to the thigh frame, the thigh support configured to support a rear surface of the thigh of the user, and

a knee joint driver configured to connect the shank frame and the thigh frame, the knee joint driver configured to drive the thigh frame to assist the sit-to-stand motion of the user by transmitting a power from the knee joint driver to the thigh frame,

wherein, as the knee joint driver drives the thigh frame, the power is not directly transmitted to the driving frame until the thigh frame moves relative to the driving frame to a position where the protrusion interacts with an end of the elongated guide corresponding to a completion of the sit-to-stand motion, the knee joint driver configured to adjust an angle between the thigh frame and the shank frame, thereby assisting a motion of a knee joint of the user.

2. The motion assistance apparatus of claim 1 , wherein the thigh frame is configured to move relative to the driving frame.

3. The motion assistance apparatus of claim 2 , further comprising:

a connector having a first end and a second end, the first end of the connector being connected to the driving frame and the second end of the connector being connected to the shank frame such that the connector is configured to transmit the power of the driving frame directly to the shank frame.

4. The motion assistance apparatus of claim 3 , wherein a length of the thigh frame is less than a length of the driving frame.

5. The motion assistance apparatus of claim 1 , wherein the guide includes a slot having an arcuate shape corresponding to a rotation axis of the thigh frame.

6. The motion assistance apparatus of claim 3 , wherein the connector is configured to connect the thigh frame and the driving frame such that the thigh frame and the driving frame rotate separately on parallel planes.

7. The motion assistance apparatus of claim 3 , wherein the connector is configured to have an elasticity.

8. The motion assistance apparatus of claim 1 , wherein an angle of the thigh frame with respect to the driving frame is variable while the driving frame is assisting the motion of the hip joint.

9. The motion assistance apparatus of claim 1 , wherein the knee joint driver is configured to not transmit the power directly to the driving frame during a portion of the sit-to-stand motion, and

the thigh frame is configured to rotate relative to the shank frame while being rigidly connected to the driving frame during a remainder of the sit-to-stand motion excluding the portion.

10. The motion assistance apparatus of claim 9 , wherein the knee joint driver is configured to assist the sit-to-stand motion of the user by transmitting the power from the knee joint driver to the thigh frame during the sit-to-stand motion such that the power of the knee joint driver is transferred to the driving frame after the completion of the sit-to-stand motion in which the thigh frame is rigidly connected to the driving frame.