This research uses newly available "indoor GPS" (iGPS) technology to generate an accurate robotic reference model from a parametric description (dimensions, compliance, etc.) of its "as-built" components (actuators, links, etc.). The new metrology system uses infrared transmitters and has sufficient accuracy to parametrically describe even high precision systems. Completing the initial model requires the construction of a 2 meter cube high-precision sensor network. Once the parameters are known, they can be used to populate a developed model allowing manipulator accuracy resolution previously attainable only at laboriously taught locations. This development then allows for the construction of open architecture manufacturing cells (1, 3, and 10 meter cubes). The iGPS and reference model will be used to "calibrate as assembled" (i.e. on demand) and maintain the cell preventing accuracy drift due to repair, upgrade, aging, temperature, etc.
The benefits of modular robots are clear. Such systems allow flexible manufacturing, rapid repair, and upgrade, but these benefits have yet to be realized. A significant barrier is the presence of error between the tool (actual) frame and goal (ideal) frame. While the repeatability (returning to a taught point) of a typical robot can be 0.005", its accuracy (commanded to a new point) may not be better than 0.1" due to configuration, load, model error, etc. Currently, teaching a robotic device is a time-consuming process required after repair, upgrade, and process change. But the accuracy is not sufficient to perform the required high-precision operations without teaching. This fact trumps other modular technology benefits. But the use of iGPS technology in tandem with actuator metrology could lead to accuracy levels close to repeatability and remove this technological barrier.
