Patent ID: 8018192

Claim:
A trajectory display device adapted to display a three-dimensional trajectory of an actual position of an object, the three-dimensional position of the object being controlled by a numerical controller, the trajectory display device comprising: a commanded position data obtaining part adapted to obtain data of a commanded position of the object at discrete time intervals; an actual position data obtaining part adapted to obtain data of an actual position of the object at discrete time intervals; a command line segment defining part adapted to define a command line segment which connects two temporally adjacent points, in relation to each point corresponding to the commanded position at discrete time intervals; an error calculating part adapted to calculate an error of the actual position relative to a commanded trajectory, the error being determined as a shorter one between (i) a length of a shortest normal line among normal lines each extending from the actual position at discrete time intervals to the command line segment at each discrete time and (ii) a length of a line segment extending from the actual position at discrete time intervals to a commanded position which is the nearest from the actual position; and at least one of an error displaying part adapted to display the error and an outputting part adapted to output the error to the outside.