Hardware-in-the-Loop-Environment for multi-directional axle testing and design of suspension systems

• Applicant: Professor Dr.-Ing. Ansgar Trächtler
• Subject Area: Automation, Mechatronics, Control Systems, Intelligent Technical Systems, Robotics
• Term: from 2017 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 386596429

Hardware-in-the-Loop-Simulation (HiL-Simulation) is a well-established test and development method for mechatronic products, especially in automotive industry. The device under test (DUT) is physically built up while models of the remaining components are simulated on a real-time system. DUT and models are coupled and emulate the entire system behaviour.Up to now, HiL simulations are not suitable for realistic multi-directional testing of vehicle axles with excitations in 6 motional degrees of freedom due tot he limited bandwidth of the actuators used. Instead, appropriate excitation signals are determined apriori by iterative learning techniques which is a very time-consuming process. Afterwards the excitation signals are applied within an open-loop control structure. This procedure does not permit axle testing with active, controlled suspension systems.HiL test of complete mechatronic vehicle axles requires a testrig permitting multi-directional, fast excitation with realistic load profiles. Such a testrig was built by the group of the principal investigator with support of the DFG and a control strategy for position control (without axle) has been developed and implemented. This testrig is the basis of the research proposal and serves for validation.The overall objective is the development of a multi-directional vehicle axle testrig for HiL-based testing of vehicle axles including active suspension systems. Focus is on the systematic realization of realistic HiL simulation environment for several fields of application. The results of the research project shall be formulated in a very general manner in order to transfer them to other fields of application. The overall objective was divided into 4 partial objectives:1. Concept and structure of the HiL-systemHere, we aim at developing a detailed system-theoretic structure oft he overall HiL-system which includes the definition of partial models and interfaces. For example, one important question is, whether forces calculated in the vehicle model should act as target values for the excitation unit which itself feeds back measured positions in the vehicle model, or vice versa.2. Detailed models of the environmentThe models of the environment (wheels, chassis, etc) have to reproduce the dynamic behaviour of their real counterparts with sufficient precision. It has to be clarified for which frequencies have to be covered and how to choose an appropriate level of modelling detail.3. Closed-loop control of the HiL-Systems with passive an mechatronic axlesWe aim at an indirect force control of the hexapod based on exact decoupling state linearisation which has already been designed for position control. 4. Procedure modelMethods and procedure shall be formulated in a general manner in order to be applicable to other fields of application.

• DFG Programme: Research Grants