New Software CoNCept forHardware-iN-tHe-Loop SyStemSMore often, there are now specialized teams working at the manufacturers and suppliers who are dedicated to a

specific task, and who work exclusively on the preparation, maintenance and execution of HiL tests. These teams

are supported by development departments, for example, ones that prepare the plant models. Ideally, these mod-

els are independent from the ECU to be tested. As an alternative there are also complete libraries of plant models

for the different applications and ECUs. During the course of a project these models must be connected to the

I/O configuration to create a functioning HiL test system. Supporting this task conveniently is one of the major

requirements a new HiL software concept has to fulfill, and dSpace’s ConfigurationDesk is the solution.

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new specIfIcatIons from the clIents

For many years now, hardware-in-the-loop (HiL) simulation is a standard, integral part in the automotive industry for the release process of electronic control units (ECUs). However, the requirements on the HiL test systems and the processes that support them have changed significantly in the past few years. More often, there are now spe-cialized teams working at the manufactur-ers and suppliers who are dedicated to a specific task, and who work exclusively on the preparation, maintenance and ex ecution of HiL tests. These teams are sup-ported by development departments, for example, ones that prepare the plant mod-els. Ideally, these models are independent from the ECU to be tested. As an alterna-tive there are also complete libraries of plant models for the different applications and ECUs. During the course of a project these models must be connected to the I/O con-figuration to create a functioning HiL test system. Supporting this task conveniently is one of the major requirements a new HiL software concept has to fulfill, and dSpace’s Configuration Desk is the solution.

In addition to the software, the require-ments on the hardware have also changed. Quite often in the past, new HiL systems were purchased for each new project. How-ever today, due to the complexity and high number of ECU variants, an HiL system that offers higher flexibility and adaptabil-

ity is a necessity. This flexibility is in de -mand not only during the individual tests, but also before and during commissioning because quite often the specifications change. For example, during the course of a project, the specification of a sensor out-put might change from an analog voltage signal to a PWM signal. The new Scalexio simulator with its flexible HiL hardware offers a solution for this task. ❶ shows a possible set-up.

flexIbIlIty

Just like the adaptable hardware, the con-figuration software of the HiL has just as many possible settings. For example, in the software it is possible to configure which physical properties a multifunctional chan-nel should represent (e. g., analog or digi-tal, voltage or current). Because the chan-nels can be configured via software and used for various tasks without any hard-ware modifications, a HiL system can be used for different test tasks just by load-ing a new project.

All this flexibility must remain manage-able. dSpace’s configuration software Con-figuration Desk is the key here. This pro-gram performs all of the necessary tasks related to configuration and commission-ing, as well as to operation and mainte-nance. As a result, within a project the en -tire documentation of the HiL can be saved – from the ECU to be tested, to the hardware configuration, to the plant model.

dIpl.-Ing. martIn rühlis product Manager for

Hardware-in-the-Loop Simulators and responsible for the product ConfigurationDesk from dSpace

in paderborn (Germany).

dIpl.-Ing. (fh) björn mülleris product Manager for

Hardware-in-the-Loop Simulators and responsible for the

bus system products from dSpace in paderborn (Germany).

AUTHOrS

❶ Scalexio with various I/O boards with multifunctional channels

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One particular advantage is that this occurs without any additional effort. With the new software concept this happens completely automatically because the entire signal chain, from the ECU to the plant model, is specified directly in the software.

In addition, with Configuration Desk it is also possible to save all of a project’s components, such as the ECU description, the description of the I/O configuration, the applied hardware, and the interfaces to the plant model, in separate files. These individual components can then be easily reused in later projects. ❷ illustrates the signal chain of an HiL system and its logi-cal representation and documentation in Configuration Desk.

optImIzed development process

A typical workflow for preparing a new HiL system starts with an analysis of the ECUs to be tested. The interfaces of the ECUs, meaning the number of connections and pins with the corresponding pin char-acteristics, are described completely inde-pendently from the test scenarios that fol-low. This makes it possible to use them later on for further HiL projects.

Typical pin characteristics are the logi-cal signal names with a description, the signal directions (the input or output of the ECU), physical signal characteristics

(voltage or current signal), as well as in -formation on whether a specified electri-cal error may be switched on and which loads the ECU expects on this pin. The manufacturer of the ECU usually has all of this data. However, quite often a manu-facturer-specific format is used. Because the HiL configuration tool must be able to import such data in a general format, a simple Excel sheet is a good format for data exchange.

For the ECUs to behave on the HiL later on just like in an actual vehicle, all of the signals required by the ECU (inputs/outputs as well as bus signals) must be provided by the HiL in real time. The calculation of these signals for the HiL interfaces is per-formed in the plant model of the actual vehicle. Depending on each individual test scenario, this model must simulate some parts of the vehicle with exact precision, while other parts must be calculated just relatively. To keep the models as inde-pendent from the respective test scenario as possible, the Scalexio software concept separates the plant model from the HiL hardware configuration. As a result, the Simulink plant model does not contain any information on the hardware configu-ration of the HiL system. Instead, the model ends at the general interface blocks. These blocks, in turn, can be used in the config-uration tool for connecting to the I/O func-

tionality, which was modified to match the respective test scenario. With this method, the models and hardware configuration can be developed in parallel and reused for various different test projects.

In general, the models can be modified via parameters to fit the specific type of vehicle to be simulated. The models can therefore also be prepared independently from the concrete HiL project or be present in a library. For the respective HiL project, the model “only” needs to be parameter-ized and then connected with the I/O functions of the HiL.

One of the last steps is to connect the ECU to be tested with the plant model. To do so, the logical signals (e. g., pressure, temperature or speed) of the plant models need to be converted into electric signals and transferred to the ECU via standard I/O (e. g., analog current values) or bus signals (LIN, CAN, Flexray). I/O functions are used for this. They are application-specific and project-specific, for example, to generate an analog current.

To maintain a general overview, even when several ECU pins and I/O functions are involved, Configuration Desk has self-definable views. These views allow the user to model specifically selected individ-ual functions or entire signal paths, and to show or hide them. Since a signal path can be displayed in several layers, the pro-

❷ Signal chain documentation in the configuration software

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gram also includes the option to show dif-ferent hierarchy levels of the views.

As a last step, the I/O functions must be assigned to a specific hardware channel. The assignment can be done manually as well as automatically because the software is capable of identifying the matching multi-functional I/O channel for each I/O func-tion. This configuration step can also be saved so that it can be reused in later pro -jects. In addition, an automation interface makes script-based configuration possible.

Since the software documents each con-figuration action, the entire signal path of the pins to the ECU to be tested up to the I/O channel and simulator connector pin is known by the software, and it can be

reconstructed at any time, which makes it quite easy to reuse later or to perform trou-bleshooting. In addition, Configuration Desk can create and manage the informa-tion on the necessary cable harness between the ECU and the simulator.

Once the configuration of the HiL sys-tem has been completed, code generation begins. During this process, Configuration Desk controls the generation of the code for the plant model, creates the I/O code sections, and links all of the components into a real-time application, which is loaded onto the HiL hardware and started, ❸.

During the project, I/O configurations often need to be changed, whereas the plant model remains the same. Due to the

separation of the I/O configuration from the plant model, only new code for the modified sections need to be generated. The unchanged sections can be reused. This means that a considerable amount of time can be saved during the course of the HiL project. Configuration Desk com-bines the well known functionalties from the real-time interface (RTI) with news functions that arise from the changed requrirements in the HiL simulation. In particular, the possibility to reuse all sec-tions of the configuration separately in combination with the multifunctional hardware offers a flexibility and scalability for HiL simulation that has never existed before.

❸ Configuration Desk with its various work areas

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