A supplementary metrology position coordinates determination (SMPD) system is used with a robot. “Robot accuracy” (e.g., for controlling and sensing an end tool position of an end tool that is mounted proximate to a distal end of its movable arm configuration) is based on robot position sensors included in the robot. The SMPD system includes an imaging configuration and an XY scale and an alignment sensor for sensing alignment/misalignment therebetween, and an image triggering portion and processing portion. One of the XY scale or imaging configuration is coupled to the movable arm configuration and the other is coupled to a stationary element (e.g., a frame above the robot). The imaging configuration acquires an image of the XY scale with known alignment/misalignment, which is utilized to determine metrology position coordinates that are indicative of the end tool position, with an accuracy level that is better than the robot accuracy.