Development of the Driver Control Station DAS4000 by means of LabVIEW
Initial situation and project task
Pierburg Instruments develops, produces and distributes measurement equipment for roller dynamometer test stands and engine test stations for automobiles over the world. Based on innovative measurement processes, emissions and particles are analysed according to worldwide legislations.
These test stands simulate exactly defined street drives. Testing methods meet country-specific legal parameters and all requirements by the automotive development processes. An important task for the simulation of street drives is the exact definition of the route by a suitable control device, such as the DAS4000 (Drivers Aid System).
The new version of the DAS4000 was expected to be applicable as a stand-alone device or as build-in module for the complete automation of roller dynamometer test stands. It should offer a modern GUI and meet the demands of the latest legislations. It should be able to visualize the simulated route continuously, offering an update frequency of 20Hz. It should be remote-controllable via TCP/IP and RS232. Analogue and digital signals should be generated and imported. Finally, the system should comprise an integrated help file (PDF).
Implementation and challenge
The integrated hardware consists of a PC including a high-performance graphics board, a network interface, a CanOpen card, a CanOpen bus coupler and several I/O modules.
The software solution is based on a Windows operating system, NI LabVIEW, Acrobat Reader and a CanOpen device driver DLL. By means of this DLL, the device can be operated by a remote control. An OPC server can be provided with all measurement data.
Design and operational concept of the application have been developed in cooperation with a well-known industrial designer. All possibilities offered by LabVIEW have been united as a design study. Based on this study, an operational concept and a concept for the operator interface have been generated.
The help function has been implemented by means of an Acrobat-Reader-Plug-In and an ActiveX-Container. For driving tests, it is possible to choose one of three different views. The route is visualized as an XY-graph. Actual speed, tolerance zones and nominal values for time and speed are displayed.
Before the test starts, all data is transferred to user memory, so that no time-critical hard disk access is required during testing. In case of time differences, despite these protective measures, a special algorithm is responsible for slight modifications of the update rate so that nominal values are met, again. It is required to meet nominal values, exactly, because the test has to extract waste gas samples at statutory moments. Automated control of this process is realized via digital outputs of the process interface.
This process interface consists of a CanOpen card, a suitable VI library and an I/O system including a CanOPen bus coupler. It imports vehicle and test stand data and measures speed, oil temperature and ambient temperature via analogue inputs. All control data can be visualized on demand.
Pierburg Instruments develops, produces and distributes measurement equipment for roller dynamometer test stands and engine test stations for automobiles over the world. Based on innovative measurement processes, emissions and particles are analysed according to worldwide legislations.
These test stands simulate exactly defined street drives. Testing methods meet country-specific legal parameters and all requirements by the automotive development processes. An important task for the simulation of street drives is the exact definition of the route by a suitable control device, such as the DAS4000 (Drivers Aid System).
The new version of the DAS4000 was expected to be applicable as a stand-alone device or as build-in module for the complete automation of roller dynamometer test stands. It should offer a modern GUI and meet the demands of the latest legislations. It should be able to visualize the simulated route continuously, offering an update frequency of 20Hz. It should be remote-controllable via TCP/IP and RS232. Analogue and digital signals should be generated and imported. Finally, the system should comprise an integrated help file (PDF).
Implementation and challenge
The integrated hardware consists of a PC including a high-performance graphics board, a network interface, a CanOpen card, a CanOpen bus coupler and several I/O modules.
The software solution is based on a Windows operating system, NI LabVIEW, Acrobat Reader and a CanOpen device driver DLL. By means of this DLL, the device can be operated by a remote control. An OPC server can be provided with all measurement data.
Design and operational concept of the application have been developed in cooperation with a well-known industrial designer. All possibilities offered by LabVIEW have been united as a design study. Based on this study, an operational concept and a concept for the operator interface have been generated.
The help function has been implemented by means of an Acrobat-Reader-Plug-In and an ActiveX-Container. For driving tests, it is possible to choose one of three different views. The route is visualized as an XY-graph. Actual speed, tolerance zones and nominal values for time and speed are displayed.
Before the test starts, all data is transferred to user memory, so that no time-critical hard disk access is required during testing. In case of time differences, despite these protective measures, a special algorithm is responsible for slight modifications of the update rate so that nominal values are met, again. It is required to meet nominal values, exactly, because the test has to extract waste gas samples at statutory moments. Automated control of this process is realized via digital outputs of the process interface.
This process interface consists of a CanOpen card, a suitable VI library and an I/O system including a CanOPen bus coupler. It imports vehicle and test stand data and measures speed, oil temperature and ambient temperature via analogue inputs. All control data can be visualized on demand.
For host connection, the DAS4000 uses a standardized protocol
(VDA-AK-SAMT), developed by German users of for roller dynamometer test
stands and engine test stations. This protocol allows for remote
control, data acquisition and parameterization via RS232 or TCP/IP. Due
to TCP/IP support, the DAS4000 is able to work parallel to other
application of the tester system on the same PC.
During each test drive, current values are recorded, so that they can be used as default values for the next test drive. After each test, data is analyzed and stored to result files. It is also possible to view and print test files of current and past tests. These files contain data regarding the number and the uration of violations of limiting values, covered distances and the time of the beginning and the end of the test.
Testing results are stored to the hard disk as ASCII files and can be selected by means of an explorer. They can be created and edited by a text editor.
In addition to normal test drives the software includes a ‚Coast Down’ test, which can be used for the determination of the coasting behaviour of a vehicle. For this test the vehicle needs to be accelerated to a speed of 130 km/h with subsequent coasting. Related times are measured and recorded. By means of this method it is possible to check the adjustment of the rolls. It can also be verified, whether coasting on the test stand is identical to coasting in the street.
Conclusion and future prospects
Due to its modular concept and its programming environment, the DAS4000 software can easily be configured, extended and modified according to any future demands. Number and appearance of analogue indicators, such as tachometers and thermometers, can be parameterized. All configuration data is stored as an ASCII file and can be edited by means of a test editor.
A suitable extension for the DAS4000 software is a configurations editor, which allows for configurationally changing at run-time. The DAS400 can also be used for any other applications, testing vehicles on a roller dynamometer test stand.
During each test drive, current values are recorded, so that they can be used as default values for the next test drive. After each test, data is analyzed and stored to result files. It is also possible to view and print test files of current and past tests. These files contain data regarding the number and the uration of violations of limiting values, covered distances and the time of the beginning and the end of the test.
Testing results are stored to the hard disk as ASCII files and can be selected by means of an explorer. They can be created and edited by a text editor.
In addition to normal test drives the software includes a ‚Coast Down’ test, which can be used for the determination of the coasting behaviour of a vehicle. For this test the vehicle needs to be accelerated to a speed of 130 km/h with subsequent coasting. Related times are measured and recorded. By means of this method it is possible to check the adjustment of the rolls. It can also be verified, whether coasting on the test stand is identical to coasting in the street.
Conclusion and future prospects
Due to its modular concept and its programming environment, the DAS4000 software can easily be configured, extended and modified according to any future demands. Number and appearance of analogue indicators, such as tachometers and thermometers, can be parameterized. All configuration data is stored as an ASCII file and can be edited by means of a test editor.
A suitable extension for the DAS4000 software is a configurations editor, which allows for configurationally changing at run-time. The DAS400 can also be used for any other applications, testing vehicles on a roller dynamometer test stand.