How to reduce testing time and cost? Let's take a look at the Hardware in the loop－HIL/MIL/SIL/PIL

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How to reduce testing time and cost? Let's take a look at the Hardware in the loop－HIL/MIL/SIL/PIL

In addition to HIL, there are other simulations for different situations and needs. With the advancement of technology, time and testing costs have become the biggest problems, and simulation has become a trend, which can improve the problems encountered in R&D. Today, let's see what other simulation methods besides HIL are available.

Introduction

Hardware in the loop (HIL)simulation

The hardware loop simulation (HIL) has been introduced before, and people often confuse it with PIL. In fact, the test purposes of these two are different. PIL is suitable for testing software and models, while HIL is for testing the controller system. The MIL, SIL, and PIL described above are all unique to the MBD development mode, and HIL is likely to be used regardless of whether it is developed for MBD or not, which is more cost-effective than physical testing.

【Futher Reading】What is a Hardware in the loop system (HIL)? How can it help you?

Model in the Loop (MIL) simulation

Model in the Loop (MIL) simulation is a test method performed at the initial stage of development and during modeling when developing embedded systems using model drivers.

Embedded systems need to interact with the operating environment,

Generally, there will be sensor signal input, and the physical system will be driven according to the input and system design.

In order to maintain the normal operation of the system, the environment of the embedded system is usually included in the simulation consideration.

As shown in the figure above, in the Simulink* model, MIL refers to connecting the control algorithm model and the controlled object model to form a closed loop. This kind of simulation test usually occurs in two cases. One is that the system engineer uses the control algorithm to verify the algorithm. The algorithm model controls the controlled object model; the other is the integration test of the model set.

*Simulink: A multi-domain simulation and model-based design tool for dynamic and embedded systems developed by The MathWorks Corporation

Software-in-the-loop (SIL) simulation

With the development of electronic control system technology, ECU (engine control unit) has become more and more widely used in cars, so the algorithm is becoming more and more complex, and the functions have begun to increase. The test cost of the car is greatly increased. Software in the loop (SIL) can set the ECU-related signals in series with the simulation platform so that the target controller can be simulated, and save the time and cost of developing the electronic control system.

In fact, the main purpose of SIL is to confirm that the automatically generated code behaves the same as the model used for code generation. At present, many companies have shifted from traditional development to a V-shaped development model*, and through SIL, problems can be found in early development and improved correction s efficiency.

*V-shaped development model: The software development of the V-model is not carried out in a straight line. The process gradually goes down before the source code stage, and gradually goes up after the source code stage, forming a V shape. The V-model points out the relationship between the phases in software development and their corresponding software testing phases.

processor-in-the-loop (PIL) simulation

In fact, SIL alone does not ensure that the code runs the same as the model on the target processor, so there is a processor loop test (PIL). The two differences are that PIL uses the target compiler to pass the generated code to the target. The processor and SIL are to use the compiler under Windows.

In fact, it is not only to prevent errors in the code generation process but there may also be bugs in the compilation process. SIL and PIL can help us find this problem.

In addition, PIL can obtain the longest running time of the algorithm on the actual controller, which can bring high value to the development engineer.

In conclusion

In recent years, time-to-market, design, and testing costs have become important indicators of the competitiveness of various industries. Some industries will consume a lot of costs during testing in the past, and even dangers may occur during the testing process. Therefore, simulation has gradually become a trend. By means of simulation, we can test whether it is feasible in the research and development process, and avoid a lot of costs and dangers, which can not only improve product quality, but also shorten product development time, create greater competitiveness in the market, and give customers good results. experience.

Main image photo by photographer: Josh Sorenson, link: Pexels

References wiki / weixin

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