Variable stiffness robotic joint system

A variable stiffness robotic joint system comprising:

• a first driving module and a second driving module configured to respectively generate torque which is rotated on a first direction;
• a first rotating module configured to change rotations of the first driving module and the second driving module into rotations on a second direction intersecting the first direction when the first driving module and the second driving module rotate in directions in which a joint is rotated in a same direction, thereby rotating the joint;
• a stiffness-providing member configured to provide stiffness by elastically supporting a rotational movement of the first rotating module on the second direction;
• and
• a second rotating module configured to change rotations of the first driving module and the second driving module into a linear motion in the first direction when the first driving module and the second driving module rotate in directions in which the joint is rotated in different directions, thereby adjusting an elastic force of the stiffness-providing member.