Hardware-in-the-loop simulation of mechanical loads for mechatronics system design

Abstract

Current research efforts in Hardware-In-The-Loop (HIL) simulations are directed toward testing Electronic Control Units, simulated digitally, in a physical experimental setup. This thesis presents different approach of using HIL simulations. Active and passive mechanical loads can be simulated physically on direct drive motors, under computer control. The work in thesis is based on effort-flow concept, which allows components of the experimental setup to be replaced as needed by physical or digital model. The only requirement that has to be satisfied is that elements of the setup retain their inputs and outputs, in the form of effort and flow pairs. Based on this theory, the new experimental setup was built, a generic HIL setup containing two DC motors, which are connected by shaft. One of the motors is used to actuate the system, while another motor represents the physical simulator. Based on the sets of derived formulas, physical simulator is able to simulate active and passive loads. Three different experimental levels are presented in the thesis. The open loop, current control and torque control experiments. The experimental results prove the concept in whole and show that theory can be applied in real world applications. The focus in this research is on simulation of nonlinear loads, whose models are presented by sets of nonlinear differential equations. Digital simulations require solutions of those equations and it is demanding job. The method of physical simulations presented in this thesis shows simpler way of simulating complex loads.