A supplementary metrology position coordinates determination system for use with a robot, the supplementary metrology position coordinates determination system comprising:
- a first imaging configuration comprising a first camera, the first imaging configuration having an optical axis;
- an XY scale comprising a nominally planar substrate and a plurality of respective imageable features distributed on the substrate, wherein the respective imageable features are located at respective known XY scale coordinates on the XY scale;
- an image triggering portion configured to input at least one input signal that is related to an end tool position of a robot and determine the timing of a first imaging trigger signal based on the at least one input signal and output the first imaging trigger signal to the first imaging configuration, the robot including a movable arm configuration with an end tool mounting configuration and a motion control system configured to control an end tool position of an end tool with a level of accuracy defined as a robot accuracy, based at least in part on sensing and controlling the position of the movable arm configuration using at least one position sensor included in the robot, wherein the first imaging configuration is configured to acquire a digital image of the XY scale at an image acquisition time in response to receiving the first imaging trigger signal;
- and
- a metrology position coordinate processing portion configured to input the acquired image and identify at least one respective imageable feature included in the acquired image of the XY scale, and the related respective known XY scale coordinate location,
- wherein:
- the supplementary metrology position coordinates determination system is configured with a movable one of the XY scale or the first imaging configuration coupled to the movable arm configuration and the other configured to be coupled to a stationary element proximate to the robot, with the stationary one of the XY scale or the first imaging configuration defining a first reference position;
- a scale plane is defined to nominally coincide with the planar substrate of the XY scale, and a direction normal to the scale plane is defined as a scale imaging axis direction, and in an operational configuration of the supplementary metrology position coordinates determination system at least one of the XY scale or the first imaging configuration is arranged with the optical axis of the first imaging configuration parallel to the direction of the scale imaging axis direction and with the scale plane located within the range of focus of the first imaging configuration along the scale imaging axis direction;
- the supplementary metrology position coordinates determination system is configured such that when the moveable one of the XY scale or the first imaging configuration and the stationary one of the XY scale or the first imaging configuration are arranged in the operational configuration, and the movable arm configuration is positioned with the XY scale in a field of view of the first imaging configuration, then the metrology position coordinate processing portion is operable to determine metrology position coordinates that indicate a relative position between the movable one of the XY scale or the first imaging configuration and the first reference position with an accuracy level that is better than the robot accuracy, based on determining an image position of the identified at least one respective imageable feature in the acquired image;
- and
- the determined metrology position coordinates are indicative of the end tool position at the image acquisition time, with an accuracy level that is better than the robot accuracy, at least for a vector component of the metrology position coordinates that is at least one of transverse or perpendicular to the scale imaging axis direction.