Tracking apparatus

A tracking apparatus comprising:

• a spherical body;
• a first gimbal supported by a bottom of the spherical body and configured to rotate about a first gimbal axis extending vertical;
• a second gimbal supported by the first gimbal and configured to rotate about a second gimbal axis perpendicular to the first gimbal axis;
• a third gimbal supported by the second gimbal and configured to rotate about a third gimbal axis perpendicular to the second gimbal axis at an intersection between the first gimbal axis and the second gimbal axis;
• a movable body supported by the third gimbal and configured to rotate about a fourth gimbal axis perpendicular to the third gimbal axis;
• three or more spherical driving units connected to the movable body and kept in contact with portions of the spherical body to move the movable body in a desired direction;
• a hold unit connecting the third gimbal to the movable body, and holding the spherical driving units pressed against the spherical body;
• an identifying unit supported by the movable body and configured to output position data of a target;
• a first angle sensor configured to detect a first rotation angle of the first gimbal relative to the bottom;
• a second angle sensor configured to detect a second rotation angle of the second gimbal relative to the first gimbal;
• a third angle sensor configured to detect a third rotation angle of the third gimbal relative to the second gimbal;
• a fourth angle sensor configured to detect a fourth rotation angle of the movable body relative to the third gimbal;
• a rotation spring driving unit configured to return the third gimbal to a center of a rotation range of the third gimbal;
• and
• a control unit configured to control the spherical driving units to track the target, using the first to fourth rotation angles.