Operation input device and method of initializing operation input device

A method of initializing an operation input device that has two or more multi jointed arms which have a plurality of joints in series having a degree of freedom of rotation or translation and are configured so that a position and an orientation of a distal end thereof relative to a proximal end thereof are changed, and a detection unit which is provided in each of the plurality of joints to detect a joint movement amount that represents a movement of each of the plurality of joints by a rotation angle or a translational displacement from an unknown initial joint value, the method of initializing the operation input device comprising:

• a holding process of holding the proximal ends of the multi jointed arms in a state in which a relative positional relationship between the proximal ends is fixed;
• an engaging process of engaging the distal ends of the multi jointed arms so that a relative position between the distal ends is fixed;
• a data acquisition process of acquiring a plurality of sets of joint movement amounts in a time series from the detection unit that is provided in each of the plurality of joints of the mutually engaged multi jointed arms while moving the distal ends of the mutually engaged multi jointed arms;
• and
• an initial value calculation process of calculating the unknown initial joint value under a condition that a relative positional relationship between the distal ends is fixed by an engagement based on the plurality of sets of joint movement amounts acquired in the data acquisition process in a time series.