Vehicle inspection application may be UK's biggest

Citation

(2002), "Vehicle inspection application may be UK's biggest", Industrial Robot, Vol. 29 No. 5. https://doi.org/10.1108/ir.2002.04929eaf.007

Vehicle inspection application may be UK's biggest

Vehicle inspection application may be UK's biggest

Keywords: Robots, Inspection, Machine vision, Automotive

Vision system measures, checks, up to 49 points on Ford Transit cross beam

A robot-enabled Cognex vision system is inspecting cross car beams for the V184 Ford Transit at the rate of 40 per hour, at the factory of Lander Automotive in Woodgate near Birmingham (see Plate 6). The system is thought to be one of the most sophisticated automated inspection systems in the UK and is based on a Cognex Checkpoint 900 vision system which checks 22 points on the 1.7m beam, with a fuller inspection covering 49 points once every hour.

Lander Automotive designs and manufactures a wide variety of tubular and seating components for the European automotive industry and produced cross car beams for the previous Ford Transit, now manufactured in Eastern Europe. In operating a policy of improving techniques, Lander reviewed the production method and decided to implement an automated inspection system for the new V184 Transit contract. The previous beam was manually gauged so the way forward, according to Project Engineer Ian Doody, was an automated alternative based on a vision system.

Plate 6 The Cognex vision system inspects cross car beams for the V184 Ford Transit

The "cross car beam" fits across the vehicle at the front of the driver's compartment. It is designed to give lateral strength but it also carries the fascia panels, glove compartments and various other items, which screw into self-tapping "cell clips" fitted into brackets welded on the beam.

The beam is manufactured by bending a steel tube on a CNC machine, and then mig-welding on brackets using two automated welding systems followed by the manual insertion of I/P (instrument panel) retaining clips. The finished beam is then placed into the robot inspection cell, where an ABB robot arm fitted with a Cognex camera undertakes a full dimensional study of 22 points along the beam, as well as ensuring that the I/P clips are present and inspecting the weld studs. All measurements are taken relative to car line position.

The Checkpoint 900 software makes a series of decisions based on these measurements and decides if the beam is within acceptable tolerances. In the rare occurrence that it is not, the beam is removed for rework. A fuller inspection is performed every 40 beams to provide a more detailed picture of production trends. When the Vision system accepts good beams, they are ink marked as OK and a label is automatically printed giving the beam number, the weld cell involved, the manufacturing date and a part number designating LHD or RHD.

To give an idea of the size of the program, about 70 pages of A4 paper are used in a print-out. This is an unusually large Checkpoint program because it is able to inspect a virtually unlimited number of inspection points on both left-hand and right-hand beam versions. Any of the inspected points can be one of seven types of inspection (e.g. clip presence, stud position, hole position). Parameterisation is done by "training" the robot on a "golden part", the robot moving to a particular point, issuing a "train" command and Checkpoint running an "inspect" and recording the results internally. Then, when a "run" command is subsequently issued on a production unit the live results can be compared to the results gained at the "train" point and any differences compared. A pass/fail result is then sent to the robot controller.

The Checkpoint program runs on a local PC and all production data is retained for analysis. Three times each day the cell is stopped for a few minutes to allow the operator to trigger an export of data into a spreadsheet and an upload to the company server where it is stored and then archived for future reference and process improvements. Anyone with access privileges can study production data from any shift or even for an individual beam, which is useful for analysing productivity and trends. Approximately 4MB of data is stored per shift.

One of the core beliefs at Lander is continuous improvement. To improve, we need to know our starting point, which in this instance is provided by the Cognex camera system currently in use. The information is collected and reviewed to establish exactly where our trends are and the necessary steps are taken to ensure that our process is constantly moving forward.

Start of production was in January 2000 and since then the system has operated 24 hours a day almost without respite.

Contact: Katrina Dixon, Cognex UK, Units 7-9, First Quarter, Blenheim Road, Epsom, KT19 9QN, UK. Tel: 0800 0180018; Fax: +44(0)1372 754 150; e-mail: kdixon@cognex.com