Application of Virtual Instrument Technology in Automobile

As an indispensable component of the development of science and technology, test instruments have played a great role in promoting the improvement and development of scientific level. With the development of science and technology, especially the continuous improvement of electronic technology, the progress of testing technology has been greatly promoted. Against this background, the United States successfully developed virtual instruments (Visual Instruments, referred to as VI) in the late 1980s. Abroad, virtual instrument technology has been booming in the automotive and engine industries. Many foreign universities, especially some companies, have developed many related products, such as San Diego State UNIversity (University of San Diego, USA) has developed a simulation and optimization system for hybrid vehicle fuel consumption and emissions. In China, virtual instrument technology is still relatively unfamiliar to many people and has not been widely popularized, but now gradually many companies and universities have begun to apply virtual technology to production and scientific research. Some domestic universities have combined virtual instrument technology, especially LabVIEW, with scientific research experiments, and have achieved certain results in engine test monitoring, engine vibration analysis, and gasoline engine comprehensive testing.

2 Virtual Instrument Technology

The so-called virtual instrument is to use the existing computer, plus specially designed instrument hardware and special software, to form a new type of high-end and low-priced instrument that has both the basic functions of ordinary instruments and special functions that ordinary instruments do not have. Virtual instruments replace traditional instruments, change the way traditional instruments are used, improve the functions and efficiency of instruments, and greatly reduce the price of instruments. Users can use the same hardware system and use different software programming to give full play to their talents and imaginations, design their own instrument systems at will according to their wishes, and realize various measurements with completely different functions. It can be seen that the software system is the core of the virtual instrument. The software can define various instruments, so it can be said that "software is the instrument". In the entire virtual instrument, the computer, which is what we often call the PC, is the soul of the virtual instrument.

The hardware system of virtual instruments is generally divided into a computer hardware platform and a measurement and control function platform. According to the different measurement and control function hardware, virtual instruments can be divided into four standard architectures: GPIB, VXI, PXI and DAQ, which are used for signal acquisition, transmission and control. The hardware structure of the virtual instrument system is shown in Figure 1.

Compared with traditional test instruments, virtual instruments not only have the characteristics of object-oriented applications, but also have the appearance, practicality and operability of real instruments. Their main advantages are as follows: (1) The detection function can be realized relatively easily; (2) The human-computer interaction interface is clear and beautiful, and easy to construct; (3) The system has great flexibility and can be modified and redefined as needed; (4) The development cycle is short and the cost is low.

3 Application of Virtual Instruments in Automobiles

3.1 Application of Virtual Instruments in Torque Converters

The performance of the torque converter directly affects the driving safety of the car. The virtual instrument technology can be used to measure the performance parameters of the torque converter at different speeds and inlet pressures (as shown in Figure 2). The test design and system resource configuration as well as the playback and printing of test data are completed through the human-machine interface. The main console is responsible for the communication and coordination between systems. It calls the instrument driver according to the initial information, receives the test signal fed back from the I/O port, and after data processing, sends a control signal to make the torque converter reach the predetermined state and keep it stable, while performing performance tests on the state. This system is significantly better than traditional testers and is more conducive to the expansion of system functions and the development of intelligent testing and diagnosis.

3.2 Application of Virtual Instruments in Automobile Braking and Handling Stability

In the traditional automobile braking and handling stability test process, five-wheel instrument, non-contact speedometer, azimuth gyroscope, vertical gyroscope and other instruments are mainly used. Most of these devices are complex in structure and high in cost. Some parameters have large measurement errors. There is no supporting software for comprehensive testing, and data processing is inconvenient. However, the use of virtual instruments can easily solve the problems in traditional testing (as shown in Figure 3).

This system is mainly composed of interface circuit, software and virtual instrument panel. The hardware can realize the interface with PC, that is, complete the functions of analog-to-digital conversion, digital input and output, counter/timer operation, etc. The software includes driver interface and instrument function program. The comprehensive automobile test system composed of the above test principles overcomes the shortcomings of some hardware detection instruments that need to use analog trackers to draw curves and rely on manual identification and recognition, and realizes full digital processing.

3.3 Application of Virtual Instruments in Vehicle Anti-lock Braking Systems

The vehicle anti-lock braking system (ABS) is an effective component for reducing traffic accidents. By introducing virtual instruments into ABS, not only can the signal acquisition and control, analysis and processing, and result display contained in traditional instruments be realized in personal computers, but users can also easily change, increase or decrease the functions and scale of instruments by modifying the software according to their own needs. This system (as shown in Figure 3) can not only complete the acquisition, processing, and analysis of input data, but also complete the analysis and result display of output data. More importantly, it can easily change the anti-lock control mode and use different control modules for control to study the effects of multiple modes, reducing the investment in test instruments.

3.4 Application of Virtual Instruments in Axle Testing

Although the road test of the whole vehicle drive axle can truly reflect the actual situation during driving, it consumes a lot of manpower and material resources, and the test cycle is very long and difficult to control. The performance test of the drive axle assembly using the indoor bench test method can detect problems earlier. The HCQ-3.0 test system based on virtual instruments (as shown in Figure 4) is mainly composed of a road simulation system (mainly including rollers and flywheel groups), a hydraulic loading system, a data acquisition and control system, a computer monitoring and analysis system, a power transmission system (mainly including engines, clutches, transmissions, and drive shafts), axle clamping systems, and safety protection devices. The HCQ-3.0 test software controls the test system and completes the performance test of the automobile drive axle together with the test bench, as well as data acquisition, processing, analysis, display, and storage, and performs test file management.

4 Conclusion

Foreign virtual instrument technology has been widely used in various fields and has been used in vehicle testing and production for many years, while the application of this technology in my country is relatively late. Since virtual instruments have many of the above characteristics, they can greatly save project capital investment and improve benefits and efficiency, so they are worth promoting in the automotive field. At present, PC-based virtual instrument technology is developing towards high performance, multi-function, integration and networking. Virtual instrument technology can promote the development of vehicle test instruments and has good application prospects.