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Vehicle suspension test rig with highly dynamic hexapod

DFG project on hardware-in-the-loop simulation of mechatronic vehicle axles

Nowadays, vehicle suspensions have an increasing number of electronic components that improve driving comfort and safety. The development and testing of such mechatronic systems requires the use of efficient testing systems. The aim is to minimise the number of time-consuming test drives and to replace them by means of fast and reproducible tests in the laboratory.

Multidirectional vehicle suspension testing with a hexapod

With the support of the German Research Foundation (Deutsche Forschungsgemeinschaft DFG,), a novel test concept for the multidirectional excitation of entire vehicle axles has been realised. The test rig consists of a hydraulic hexapod with six hydraulic cylinders in a parallel-kinematic arrangement and allows to simulate a realistic spatial load on the vehicle axle. The key feature of the test rig is its control concept and the underlying design of the dynamic behavior of its components which together facilitate high-dynamical closed-loop control operation. In common test rigs for operational stability, the excitation signals are realized via unflexible open-loop control involving time-consuming iterative learn procedures. In contrast, in our test rig, the excitation signals are  realized by a closed-loop control  structure in real-time directly from the measurement data.

Hardware-in-the-Loop simulation

Beside conventional suspension and axle testing, where measured or synthetic road profiles are directly applied, also the use in Hardware-in-the-Loop (HiL) simulation is possible. Widely used in the development of electronic control units, the HiL-method aims to test a component without physically realising the remaining system. Analogously, within a HiL simulation of mechatronic vehicle suspension systems only the suspension system is physically built up, while the remaining vehicle components (car body, tires, driver and environmental influences) are simulated on a real-time computer. The coupling of the vehicle suspension and the remaining vehicle models is realised by the hexapod as actuator and sensors (e.g. force sensors). The HiL technique enables development and testing of active chassis control systems like active roll stabilisers or dampers within the entire system assembly. This research project is also funded by the DFG.