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  orange box Laser guided robot motion control for sputter machine loading at IBM.
The Challenge


Disk drive platters ("disks") are loaded onto a vertical plate ("pallet") with cavities to house the disks and transport them into the sputtering machine. The disks are held in place inside the cavities by small grooves. The task is complicated by the fact that the pallet warps as it goes through hot and cool cycles of the sputtering process.  IBM required that the system be agile, - a program that could be rapidly reconfigure itself for different disk sizes (95, 65, 48, 34 mm) and pallet geometries.

ACG solution

A laser range sensor was used to "map" the pallet at the locations in between the holes. The gains of the servo controlling the robot joints was modified to make the robot "stiff" while readings were taken. The optimal loading locations of each set of three disks was then computed. The range sensor readings were fed directly to the robot servo motion controller for real time, on-the-fly sensor guided control. The software control layer has been written to work on both Ulvac and Leybold sputter machines. 

Automatic code generation. Modifying the code written for 65 mm disks to work for 95 mm disks was accomplished in 1 hour despite significant differences in the sequencing and the geometry of the pallet and grippers. This rapid turn around was achieved by developing an automated robot motion planner which generated a "motion highway map". We thus eliminated the arduous task of specifying specific motions. Instead we supplied the motion manager with a map of the highways and a set of algorithms to compute, depending on the current robot location, the best route. If the cell is reconfigured, some highways become "closed" and the system re-computes the new route. The algorithms was first simulated and then converted to robot program code. 
This approach was adopted to run on both the Ulvac and Leybold Sputter machines in IBM plants in the US and Germany. 


Agile systems require the ability to write the program that generates working code for specific configurations. Our approach to developing agile system code enabled IBM to complete software development for the Ulvac system is 90 days.