The following is an article that appeared in Design News.
The automotive industry is the sector where robots have experienced their greatest application and success. It remains, however, a sector still not saturated. Even in body shops, where robots are extensively used for spot welding, new jobs are being found for these highly flexible devices.
One such task is checking the finish-welded body. To improve tolerances, vehicle manufacturers are moving towards 100% inspection of the body-in-white car. The most common inspection technique uses non-contact laser sensing, Laser sensors – some 150 are required for a single model - mount on a tunnel-like structure through which the body-in-white passes. If the model changes, the equipment must be adapted or altered.
French systems integrator BBR is replacing the tunnel-like structure with a team of robots at the PSA Peugeot Citroen factory in Rennes, France. The managing director, describes the setup: Four Fanuc robots manipulate Perceptron laser sensors; a Dynalog calibration system compensates for temperature variations in the factory environment. Communication interfaces are based on the Siemens Profibus.
Once in operation, each robot will measure 10 to 15 points on each welded body, in a cycle time of 24 seconds, with a precision of 0.2 mm. The calibration cycle is designed to be spread out over the passage of three or four cars in order not to disrupt production output. It involves each robot performing a self-check routine. If this highlights the presence of a positioning error, the supervisory PLC on the line initiates a complete calibration for all the robots.
PSA Peugeot Citroen is installing two robotic cells of this type to inspect a mix of seven models of car being produced on the same line. One cell will be used to measure the under-body of the vehicles and the other for the main part of the body.