Driver torque estimation apparatus and steering system including the same

A driver torque estimation apparatus, comprising:

• a first shaft to which a steering wheel to be used for steering a vehicle is coupled;
• a second shaft coupled to the first shaft via a torsion bar;
• a torque detection unit configured to detect a torsion bar torque applied to the torsion bar;
• a rotation angle acquisition unit configured to acquire a rotation angle of the second shaft;
• a basic driver torque estimation unit configured to estimate a basic driver torque by using a disturbance observer based on the torsion bar torque and the rotation angle of the second shaft;
• a gravity torque calculation unit configured to calculate, by using a rotation angle of the steering wheel, a gravity torque applied to the first shaft by gravity acting on a center of gravity of the steering wheel;
• and
• a driver torque estimation unit configured to estimate a driver torque by using the basic driver torque estimated by the basic driver torque estimation unit and the gravity torque calculated by the gravity torque calculation unit.