SPARC: Results and Application
The new sPC (small passenger car) VeHiL test bench, developed in the SPARC project, was introduced in June 2005. Schenck Final Assembly Products Püttlingen had been working on the development of test benches for new vehicle generations with the aim of testing the majority of all drive-by-wire functionalities of a vehicle, and has now produced the first prototype of the new generation of test benches at DaimlerChrysler in Untertürkheim.
Official presentation of the sPC VeHiL
On June 22nd, 2005, the first official presentation of the sPC VeHiL, one of the two test benches planned and implemented within the EU project SPARC, took place at DaimlerChrysler Untertürkheim. Since July, the test bench has been open to development engineers from Daimler Chrysler, Schenck FAP and all other partners of the SPARC project. From now on, we will learn about the possibilities and potentials regarding the development of new vehicle technologies and functionalities on mechatronic and intelligent systems.
The potentials of the sPC VeHiL test benches
The sPC VeHiL test stand and the prototype of the new generation of test stands are of great interest for future vehicle development. Due to their rigorous modular design, these test benches have the potential to test the majority of all mechatronic and mechanical components of the modern car in the development phase and also in the final (EoL) tests within the final assembly line (see below). By rigorously using the new generation of test benches, OEMs are now able to take full advantage of the advanced concept. From the development of modern vehicles, with their various components and integrated systems, to the vehicle production process, in which all the necessary test procedures during final assembly guarantee high product quality and smoothly functioning systems.
Advantages for development
With the 4-motor concept of the Schenck Final Assembly Products (used for more than 9 years within the framework of the joint final test benches "x-road") it is possible to simulate almost every situation in which a vehicle could also come on a real road and with the advantage of a very high reproducibility!
In addition to the possibilities of a common x-road roller dynamometer to test the curves (also with different wheel speeds and the application of different slip coefficients for each wheel and also a real front wheel steering angle, Fig. 3) road inclinations and braking forces can be simulated. The resulting lateral accelerations on the bodywork and the shear angles during cornering can be simulated by a parallel vehicle simulation and are transferred to the corresponding vehicle control units (Fig. 4) by means of proper operation of the communication units (e. g. via CAR Link, another Schenck FAP product).
Other possibilities of the new VeHiL test benches in vehicle development are:
- The test bench provides an integrated concept for functional tests and complete vehicle tests
- Test runs for established vehicle functions can be fully automated
- Documentation of certain test runs can be fully automated and used as a concept for final production.
- Compilation of visualization / tools based test cases
- Tests with a real vehicle under real conditions (road simulation)
- Real, the dynamic behavior of the powertrain without the use of complex simulations
- High reproducibility
- Optimization and preparation of winter tests on stationary test benches (highly reproducible roads and laboratory conditions)
- Reproducible acoustic tests (NVH) within the entire drive train
- Tests with different coefficients of friction ESP Plus, real ASR tests, ABS Plus, mue-Split,....
A complete road simulation including all occurring forces and torques in the wheel suspension (e. g. track and camber changes during cornering, pressure and torques while lateral forces on the tyre contact surface) can be applied to the entire vehicle with the help of special small simulation actuators on the sPC VeHiL test bench, at all possible operating degrees of freedom.
Advantages in vehicle production
The new generation of test benches, the Inline Function Tester (IFT), brings further advantages of the new concept to the assembly line.
Taking a closer look at today's (EOL) test procedures, Schenck Final Assembly Products engineers identify certain optimization potentials. According to the interests of cycle time, today's final assembly of production lines is divided into up to 6 parallel final test benches (axle measurement and roller test benches, Fig. 5). After the last conveyor belt and the final apron belt, the vehicle drives through the power of its own engine into the described test field (worker). Due to human influence and the division of a production line in so many test benches, the process itself is not optimized for time, space, structure and other facts. In addition, enormous ventilation is required because of the car exhaust gases and other vapours (e. g. evaporation from the engine maintenance etc.) in this large test area. At the end, after the dynamic roller dynamometer, almost all OEMs have a lot of trouble, e. g. with the installation of floor coverings and the so-called hot engine test, in order to check the final run-out or carry out a visual check on the underbody. With the new InLine Function Tester (IFT), based on the sPC VeHiL, Schenck Final Assembly Products succeeded in developing a fully automatic vehicle test bench within the assembly line.
The new test plant is placed directly in the production line and can be adapted automatically to the vehicle within a few seconds with the aid of special adapter discs. These adapter discs are fixed to the flange (either manually or even completely automated with the aid of robots) in an earlier step.
The vehicle is transported into the stationary IFT by means of a liftable conveyor system (Fig. 6) or a standard (non-liftable) conveyor system, which is only on one level. So that the IFT can only be adapted to almost any car system with a few small retrofits. The adapter discs can also be used as a very precise tool for track and camber measurement, as only minor adjustments are required to adjust the discs. An InLine wheel alignment (IWA) is useful directly after (or before) the IFT test bench (Fig. 7).
One of the transitions mentioned above should be the fixation of the tires directly after the IFT / IWA (Fig. 7). Here, the de-adaptation of the adapter disc can be done in a single step, together with the mounting of the tires (also only by a robot, concepts for this have already been developed).
Parallel to this step, the hot engine test can be carried out and everything that usually occurs in this area can be repaired underneath the ground clothing of the car without the need for a pit and without any logistical problems.
With the IFT, all tests that are done today on the x-road test bench can now be carried out within the production line. Schenck FAP Engineers also include steering activity and the test potential comes with this new functionality (tests of ESP Plus, superimposed steering, parking aid calibration and other driver assistance systems such as lane keeping assistant and lane change assistance, etc.).
Thus, it was found out by testing that depending on time cycles, efficient test stand and workload of the workforce, it is undesirable to replace all test stands within these changes. Rather, it makes sense now to integrate the so-called heavy tests, such as high acceleration and deceleration tests, to introduce warm engine procedures, e. g. engine calibration and corresponding electrical/electronic tests within the assembly line (see also blue stripes in Fig. 7). Tests such as vehicle handling behaviour evaluation (e. g. tracking stability) and some final electronic checks, at the end this should be carried out by a human driver (e. g. on a dynamic roller dynamometer, Fig. 9). These tests should also be carried out with the tyres.
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