The Characterization of the Time Delay Problem in Hardware in the Loop System Applications

Abstract

AbstractIn the last years, simulations have been extensively used to study mechanical systems. However, sometimes mathematical models do not adequately describe the behavior of some system components and, in some cases, only these components need to be tested. Thus, the Hardware In the Loop (HIL) technique was developed to solve these problems, allowing a real time simulation of a hybrid system composed of physical and virtual parts. Due to this characteristic and the potential cost reduction capacity, without loss of precision and reliability, the HIL technique becomes an important tool for researchers and engineers in different areas such as the automotive industry, robotics and production in general. However, the result shows that there is a time delay phenomenon between the expected and obtained signal. This paper analyzes the time delay effects in a HIL simulation by means of an example of a mass-spring-damper system. The analysis results shows that the time delay comes from the actuator dynamic response and according to the sample time used in the real time system, it strongly affects the HIL simulation transient accuracy and stability. To obtain the same result obtained in the pure simulation, a time delay compensation is applied in the model and its effectiveness was verified by a comparison between full simulated and experimental HIL results.KeywordsTime delay effectsReal-time controlHardware-In-The-Loop (HIL) simulationMathematical modeling