Surgical instrument and control method thereof

A surgical instrument comprising:

• an end effector that is opened and closed;
• a manipulation unit which has an opening and closing member that is capable of opening and closing and which is configured to open and close the end effector by manipulating the opening and closing member in a first direction by a user so that the end effector applies an acting force to a target;
• a grip detecting unit configured to acquire an information to determine whether the end effector applies the acting force to the target;
• a driving unit configured to drive the end effector to be opened and closed;
• and
• a control unit configured to control the driving unit based on the information input to the manipulation unit,
• wherein when the control unit determines that the end effector applies the acting force to the target based on the information acquired by the grip detecting unit, the control unit:
• sets an acting force increasing zone of a predetermined range in a first movable range in the first direction of the opening and closing member,
• sets a neutral zone in a remaining area of the first movable range,
• controls the driving unit so that the acting force increases with a constant gradient with respect to an amount of manipulation of the manipulation unit in the acting force increasing zone, and
• controls the driving unit so that the acting force is kept constant and non-zero regardless of the amount of manipulation of the manipulation unit in the neutral zone.