HIL Testing| Interview QA Part – 15 | Automotive | Plant Simulator | Plant Model | Embedded World
Can you introduce yourself in a few words?
My name is Gregory Rousseau, I’m a Product Owner for 3 years at AVSimulation. I’m in charge of defining the Roadmap, monitoring the progress of developments, while anticipating or listening to the present or future needs of customers. On the other hand, I follow up some projects such as SERKET, for RUAG Défense France which develops a simulator for the DGA and in which we will integrate software interfaces developed by our team.
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Can you explain the acronym HIL?
HiL is the acronym for Hardware in the Loop. A HIL device – usually referred to as a HIL bench – consists of operating a physical element (sensor or actuator) in a simulation loop.
Today, all vehicles contain ECUs which are systems defined by inputs and outputs, and which integrate control laws in charge of controlling systems (such as ADAS, air conditioning, lighting systems, etc.).
The concrete example is to be able to test an ECU on a table, before putting it in place on a vehicle. To do this, it is necessary to feed the ECU inputs with virtual measurements (from a simulation loop) and thus see the evolution of its output values. In other words, the ECU will receive information from emulated sensors and will act on actuators, or it will give instructions to other ECUs.
A simple example is the case of a gear lever of a piloted gearbox, operated by a person: a sensor will recover the position of the gearshift, and transmit the information to the ECU (driver’s gear change request). In return, and if the validity conditions are verified, the latter will activate a gear change system. For such a system, the HIL bench can be used to test and validate either the shift sensor and/or the gearbox actuator.
The examples related to ADAS are often more complex, involving different sensors (real or simulated) and a computer that will eventually proceed to the fusion of multi-sensor data to validate the choice of a set point.
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Can you also quickly explain MIL, SIL, DIL ?
MiL: Model in the Loop. It is a test model that is not compiled. It does not yet meet all the constraints of use and integration of an embedded software (defined operating frequency, low-level layers, etc.). In other words, it is a bit of a raw product that allows the control law to be developed and the first tests to be carried out: only the algorithm of the embedded system is evaluated.
SiL: Software in the Loop. For this type of test, compiled control laws are used, thus homogeneous to what will be in the ECU. These command laws constitute the embedded software. The rest of the environment, including the hardware part of the embedded software, remains simulated.
DiL: Driver in the Loop. Here, it is a test used when a simulator driven by a driver is in the simulation loop. As soon as a physical person will control something during the simulation, we can talk about DiL. The objective of this type of bench is to evaluate the reactions of the driver to an event that occurs (display of information, sound emission of a prevention or warning signal, etc.).
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Difference in their Usage:
While structure enables us treat a number of different variables stored at different in memory , a union enables us to treat the same space in memory as a number of different variables. That is a Union offers a way for a section of memory to be treated as a variable of one type on one occasion and as a different variable of a different type on another occasion. There is frequent requirement while interacting with hardware to access access a byte or group of bytes simultaneously and sometimes each byte individually. Usually union is the answer. =======Difference With example=======
Lets say a structure containing an int,char and float is created and a union containing int char float are declared.
struct TT{ int a; float b; char c; } Union UU{ int a; float b; char c; } sizeof TT(struct) would be >9 bytes (compiler dependent-if int,float, char are taken as 4,4,1) sizeof UU(Union) would be 4 bytes as supposed from above.If a variable in double exists in union then the size of union and struct would be 8 bytes and cumulative size of all variables in struct.
FAQ
What types of problems can HIL test benches solve?
What is HIL testing in automotive?
What is the difference between HIL and SiL?
