Conventional hand brakes in cars are increasingly being replaced by electronic parking brakes (EPB). These automatically apply the brake during parking and release it during hill starts while adjusting the cable. Küster Automotive Control Systems is one of Europe’s market leaders among EPB suppliers. The four assembly lines on which the EPBs are produced have been fully automated with Beckhoff technology since 2003. Highlights include integrated, database-guided process monitoring and electronic calibration of the EPBs. Küster technology is used in millions of cars from a wide range of manufacturers. Components include mechanical or electronic parking brakes, window regulators, complete door systems as well as acoustic and exhaust dampers.
The requirements for control and monitoring of EPB production are complex. On the one hand production is subject to strong price pressures, which means the assembly processes must be efficient and highly automated. On the other hand EPBs are safety-relevant vehicle components which are subject to strict testing and documentation requirements. An additional complication is that an EPB is equipped with a dedicated electronic system which subsequently communicates with the vehicle and therefore must be calibrated for different operating states, for example inclination angles or braking curves. During all production stages the different manufacturing steps communicate with the central database via the C6140 industrial PC from Beckhoff.
This acts as a coupling system by automatically collecting data from all system components and transferring them to the server in bundled form. The communication between the coupling system and the assembly stations takes place via TwinCAT ADS. The C6140 also deals with remote maintenance and diagnostics. The database grants approvals for all control commands and meticulously documents the whole production and calibration process and the subsequent function test. Each individual EPB is 100% tested. The data exchange takes place at very high speeds. Depending on the scope, the response times for database queries in the control modules are around 100 ms per query. With annual production of 1,2 million EPBs, around 130 GB of table data are generated.
Control of the EPB production, the calibration and the test rigs is almost exclusively handled by Beckhoff automation technology. Küster managers were impressed by the compactness and flexibility of the Beckhoff solution, the high process speed and the impressive price-to-performance ratio. Another highlight of the Beckhoff control platform is that, in addition to pure process sequence control, force and displacement measurement can be integrated into the control system. A further advantage is the fact that communication with the EPB control electronics can take place directly from the PLC via the FC5101 plug-in card and a vehicle-specific CAN bus protocol with 11- or 29-bit CAN identifier.
Küster uses the whole range of Beckhoff products that are scalable in terms of performance. Control devices include Ethernet bus terminal controllers from the BX series, embedded PCs and industrial PCs from the C6650 generation as end-of-line computers. The software includes TwinCAT I/O, TwinCAT PLC and TwinCATNC I. The common denominator is that all controllers are operating within one network and are in synergy with the database. The EPB housings must be absolutely tight, since vehicles come into contact with water on a regular basis. The sealing process is realised via an XY table with a TwinCAT NC I controller. This is the only way to ensure constant path velocity and continuous application of the sealing compound.
The control architecture is shaped by the requirement that each step of EPB production must be approved, tested and documented. Again, it consists of the system computer and a C6650 control cabinet industrial PC with TwinCAT PLC automation software, which controls the production. The manufacturing execution system (MES) database documents everything in the process. The interactions between the Beckhoff controller and the MES system are intensive.
Around 100 controllers are connected to the database, which means that it must cope with huge quantities of data. For each electronic parking brake, approximately 250 measured values and test data are stored, of which around 150 are gathered during final, end-of-line acceptance. The documentation ensures that only approved parts are used and that the product meets the highest quality and safety standards. For every EPB produced, it is possible to trace each component and find from which batch a screw, gasket or housing originated. This is helpful in the event of a complaint, if a supplier has to concede quality defects, or in the event of transport damage.
For more information contact Kenneth McPherson, Beckhoff Automation, +27 (0)11 795 2898, [email protected], www.beckhoff.co.za
| Tel: | +27 11 795 2898 |
| Fax: | 086 603 6868 |
| Email: | [email protected] |
| www: | www.beckhoff.com |
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