SPARC: Test platform for drive-by-wire equipped vehicles in development and production
It is generally assumed that the use of electronic vehicle systems will increase considerably in the next few years due to various interest groups. Legislators want to optimize vehicle exhaust gas properties and minimize fuel consumption, while customers are interested in driving comfort and safety. In addition, OEMs are continuously improving their vehicles by creating complex systems with new functions that the customer cannot even imagine today. This technology is already built into the C5 Corvette, Acura NSX and Toyota Tundra and we can expect a growing number of new vehicles with this technology.
One of these futuristic developments is the so-called X-by-wire systems. The exclusively electronic control of the vehicle's mechanical components, also known as drive-by-wire technology, is becoming increasingly important. The goal for the future automotive driver assistance systems should be based on a common electronic platform which, in addition to the reduction of mechanical components, also includes the economisation of production processes.
Drive-by-Wire at a glance...
- Substitution of mechanical connections by mechatronic components
- Backup of each function from the computer control
- Multiple protection by redundant systems (Duo Duplex)
- Intelligent sub-controllers for each mechatronic component
- Intervention in the driving (re-)action through intelligent systems
Some of the advantages of Drive-by-Wire are:
- The extinction of the "LHD / RHD - Problem"
- Autonomous parking, even with a trailer
- Time saving on execution areas
- Accident avoidable driving
The first effective step in the European PEIT project (founded in 2002, www.eu-peit.net) was to develop a comprehensive drive-by-wire vehicle tester with an integrated drivetrain and a new vertical drive architecture. Figure 1 shows the integrated drivetrain (DaimlerChrysler AG, POS / BDS).
How do you test drive-by-wire systems at the end of the line?
Figure 2 shows a PEIT functional tester, (DaimlerChrysler). This has been achieved, but a completely secure test platform (test bench) as a development and production instrument for drive-by-wire vehicles in series production still has to be developed.
This dissertation deals with the development of a future test bench for drive-by-wire equipped vehicles. This test bench will later be used as a development tool for the verification and validation of the functionalities of the new X-by-wire components and an end-of-line (EOL) test bench for modern vehicles. The following article gives a more detailed description of the work.
IGMR, RWTH Aachen
Schenck Final Assembly Products GmbH
The first step in creating a reliable test platform is to identify the components that need to be tested in a vehicle equipped with Drive-by-Wire and clarify the test cycle to ensure that all the functionality of the X-by-Wire components is completed (Fig. 3: The figure shows a possible test structure, SCHENCK FAP, the relevant details of a vehicle equipped with a drive-by-wire system and the flow of information for a possible test situation).
For this purpose, it is necessary to develop a new generation of test benches in which new X-by-wire functionalities can be integrated. As an example, the functionality of the extended ESP, a vehicle body stabilizing function with breakage and steering interaction, can be cited. In addition, an autonomous vehicle must respond to dangerous situations such as automatically avoid accidents with pedestrians when crossing the road or other unpredictable traffic situations. This requires a decision control unit that compares the driver's "wish" motion vector (initialized via HMI - Human Machine Interface) with a so-called safe motion vector generated by the environmental sensors (EU - project SPARC - Secure Propulsion with Advanced Redundant Control, www.sparc-eu.net).
Nevertheless, it is necessary to guarantee a 100% reliable energy flow and a certain battery level in order to start a fully X-by-wire equipped vehicle (Fig. 4). In addition, new systems that temporarily store energy or change unused energy into other forms of energy (e. g. starter-generator systems, Fig. 5) are contained in such vehicles and must also be tested.
Testing such scenarios on available test benches (Figure 6: End of Tape (EOL) roller dynamometer) is not possible at the moment because the steering function tests are not included and the so-called ECOS Electronic Tests cannot assure that the intercommunication between the control units in the vehicles equipped with X-by-wire is correct.
In order to take into account the above-mentioned tests and perhaps also some unknown functionalities, autonomous and reliable test procedures and suitable test rigs must be developed. As an example of this, the PEIT hardware already developed in the Loop Functional Tester can be understood as a first step for a new generation of test benches.
As already mentioned, it can be assumed that the use of electronic vehicle systems will increase considerably in the coming years. This development will also exponentially increase the amount of information and data commands.
With the so-called 4CS (Car Communication Component Check System) it is possible to carry out system integration tests in the laboratory and in the environment of the vehicle in a completely automated manner. The tests are carried out with the so-called "button-up strategy" and are well known for the MOST system, which was developed in cooperation between DaimlerChrysler AG and BMW AG.
The present work deals with the development of such future test benches in order to realize all test scenarios and beyond that a common electronic platform for driver assistance systems for the OEM development process.