With advances in technology, development of wearable computers has accelerated. Wearable computers refer to computers that a user can naturally wear like clothes, wristwatches, glasses, or accessories. Although smartphones and tablet PCs can be conveniently used using user fingers or a touch pen, they may be inconvenient in that the user has to stow the same in a pocket or bag or carry such devices. On the contrary, the user can wear a wearable computer on the wrist or on the eyes like glasses, thereby providing convenience in portability relative to the smartphone or tablet PC. In particular, among wearable computers, a variety of wristwatch related products, for example, a smartwatch, capable of wirelessly providing various services such as weather forecasts, messages, notifications, stock quotes, etc., have emerged.
A smartwatch can detect various movements of the arm of a user because the user wears the same on the wrist. In this case, various commands may be applied to the detected movements of the arm of the user so that the user may easily control the smartwatch. Especially, the smartwatch may be configured to perform a prescribed command according to a rotation gesture of the wrist of the user. At this time, if the same angle is designated as threshold angles in the inward and outward directions of rotation of the smartwatch, the smartwatch may operate contrary to user intention. This is because the inward and outward rotation radiuses of the wrist may differ according to the current position of the arm due to the physical characteristics of the human body. Accordingly, it is necessary to designate different threshold angles according to direction of rotation in order to prevent malfunction of the smartwatch.