KUKA Flexible Production Systems is a leading producer of production systems for car bodies and chassis. When KUKA decided to become a Tier I supplier of automobile bodies to Chrysler, they needed to use their extensive knowledge of body shops and find a partner willing to work with them to change the landscape of the North American market.
KUKA was faced with designing a body shop utilizing DBOOM (Design, Build, Own, Operate, and Maintain) philosophy with no restrictions on the equipment used. The company formed a partnership with Siemens that utilized field proven revolutionary technology realizing substantial cost savings, while significantly improving system safety, manufacturing flexibility and Mean Time To Repair (MTTR). This is all happening at the KUKA Toledo Productions Operation LLC (KTPO) assembly plant, which produces the Body-In-White on the Chrysler Jeep JK vehicles, currently the Wrangler Model.
The Body-In-White application involves many systems from underbody to windshield to panel line assembly. Two main problems plagued their current design. First was the hardwired safety required for each cell was expensive to install, troubleshoot and maintain. This hardwiring of these points also made future changes and modifications costprohibitive. The other was the power distribution to robots and welders.
Traditional machine safety systems in the automotive market incorporate hard fencing, remote emergency stop pushbuttons, safety gate switches, safety mats, light curtains and large amounts of redundant relays. These systems typically employ a complicated and extensive system of redundant hard-wired circuits - making the electrical panels very large. This design inherently hampers flexibility, impedes communications to the control system, increases troubleshooting costs, and significantly increases the cost of a machine. While hardwired relay logic for control has long since migrated to the Programmable Logic Controller (PLC), little has been done to garner similar improvements in machine safety systems.
Knowing this was a major source of cost and complexity, Kuka looked to simplify the safety system with a new, more cost-effective method for safety management and control, using a failsafe controller with high diagnostic capability. While this alone would have saved thousands in wiring and troubleshooting, Kuka saw moving from hardwired safety relays to a stand-alone PLC-based method was not enough. Combining both machine safety and standard machine control on one field bus was key to eliminating most relays and “out to the field” wiring, thus reducing control panel space requirements, hardware requirements, engineering design, troubleshooting and overall wiring costs.
Kuka chose a Profibus-based processor that communicates to all field components, including safety devices, via an inexpensive two-wire cable capable of speeds up to 12 MBaud. The previous standard solution included communication via a simple field bus for control and hardwired circuits for safety which all acted independently. The architecture in that legacy design required a large five-door main control panel with auxiliary panels on the robots, roller tables and assorted field device locations. Power was supplied by expensive multi-conductor cable drops.