Abstract
Keywords - Hardware-In-The-Loop-Simulation, Heating Venting Air Conditioning (HVAC), Vehicle Air Conditioning, Climate Controller, Modified V-Model
Abstract - A modern vehicle is a complex mechatronic system which can be split into several functional subsystems on certain levels. These subsystems consist of mechanical, electronical and information processing components, those are provided from different suppliers to the vehicle manufacturer according to the claimed specifications. Usually the behaviour of the whole system can be considered at the accomplished vehicle for the first time.
More targeted is the consideration of the whole functionality of the systems from the early beginning of the development process. Thereby an optimisation of the whole system is possible through adaptation of the function and shape of the involved components instead of the additional compensation caused by the information processing part. Therefore it is advisable to ensure a structured development process for every complex mechatronic system. The modified V-Model (2) shows a possible way that guarantees a structured development and makes use of efficient Hardware- and Software-in-the-Loop-Simulation (HIL- and SIL-Simulation) for verification and validation which is usually carried out in time consuming tests.
Modern automatic air conditioning systems are, especially in vehicles of higher categories, complex systems with a wide variety of distributed mechatronic actuators and sensors. The aim of such a system is to achieve a desired climatic condition in the vehicle interior, which is defined by the temperature, the humidity and the velocity of the air flow through the passenger compartment. For the adjustment of the desired interior climate with the available air conditioning components complex control algorithms are necessary. This task is performed by the climate controller, which includes all control strategies in form of software programs. Beneath the design of a working technical system, the design of these control strategies is a further challenge. State of the art in this field is a HIL-Simulation environment based on a real time computer with adapted interfaces and additional electronic hardware. This environment enables the simulation of the air conditioning components by the use of physical and mathematical models (1) and hardware modules in real time. This technique allows a virtual test of the entire climate system in interaction with the real climate controller as well as a parameter tuning without a vehicle. Thus it is possible to reduce development time and costs (reduction of elaborate summer, winter and climate chamber tests) and to improve the quality. The pure SIL-Simulation allows the investigation of components and parameters which influence the system behaviour in interaction with a virtual controller. As consequence an automatic optimisation process can be accomplished.
In this paper the modified V-Model for the structured system development and the HIL-Simulation for property safeguarding with all its advantages towards conventional methods will be presented within the scope of a vehicle air conditioning system.