This paper discusses the problems that arise when analyzing mechatronic systems that are driven by controlled electrical drives. Both the drive and mechanics contribute to the dynamics including various sources of nonlinearities and timevarying components. The paper discusses various different means of simulating such systems, with a special reference to software-in-loop and hardware-in-loop simulations.A mechatronic system is a combination of mechanical structures, electronics, pneumatics, hydraulics, and sensor technology, also requiring program and control design. Applications from robots and manipulators to vehicles, cranes, and machine tools, to mention but a few, constitute a large variety of different mechatronic combinations. Hence, mechatronics is truly a multidisciplinary field of research and engineering.This paper discusses modeling and simulation aspects of systems that are driven by controllable electric drives or other electric actuators. The dynamic behavior of such systems depends on mechanics, the electric drive, and control.The modeling of such systems as a whole is not straightforward. However, it is important to model the whole system if we wish to capture or fix problems such as oscillation, or if we want to improve the performance of the system or achieve a higher energy efficiency. Oscillations caused by the flexible modes of mechanical structures can be determined by analytical calculations or by the FEM, at least in the case of simple mechanical structures, yet the interactions between mechanics, the electric drive, and its control are hard to solve without treating the system as a whole. The energy efficiency of electrical drives is already high, and continues to increase. However, efficiency improvements tend to be expensive and small in terms of absolute value. Often, by analyzing and optimizing the control of processes where electrical drives are used, a significant efficiency improvement (tens of %) can be achieved, often without any extra investment costs.The question is, which kinds of frequency converter, motor, and mechanics models are adequate for the simulation of such systems.
I. PROPERTIES OF MECHATRONIC SYSTEMSObviously, the characteristics of a mechatronic system vary between systems. However, some typical properties can be listed. The first, already recognized, property is the interconnection between components. There are interconnections between parts of the mechanical components, mechanics, and motor drives with their control, but also between other upper controllers such as PLCs in factory applications or the Engine Control Units (ECUs) of vehicles. In addition, the systems are connected with the environment. Examples of mechatronics systems in different environments are vehicle applications in a landscape with hills and different friction conditions, materials that are handled by material handling machines, or wind turbine applications operating in varying wind conditions.Most of the systems include nonlinear behavior to such a degree that pure linear models cannot be...