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Experimental driven demystification of system identification for nonlinear mechanical systems

Book Contribution - Book Chapter Conference Contribution

The goal here is to develop a low cost hardware-based demonstrator for system identification (SI) methods that can be used in a self-paced training kit by students as well as practicing engineers. The focus lies on hands-on training with a high return on effort. It starts from experiments that are performed on the demonstrator, a real system that can easily be used at home by the trainee without the need for external support or expensive equipment. The advantage for the SI community is that the steep learning curve, that often scares potential users of advanced SI methods, is flattened while the practical applicability is demonstrated altogether. The joint use of teaching material and hardware-based illustration provides enough knowledge, understanding and confidence to apply these methods on industrial scale systems. The first test case, which is presented here, is a mechanical setup. It consists of a nonlinear mass-spring-damper system built using commonly available components for a total cost of less than 50 Euro. When applying a signal with a low amplitude to the designed system, it almost perfectly behaves in a Linear Time Invariant (LTI) way. This is only true whenever the amplitude of the input signal is very small. Increasing the amplitude introduces weak and intuitive nonlinear distortions. Increasing the amplitude even further challenges the trainees intuition even more. A sweep up and sweep down sine test shows that the system becomes bistable around the resonance peak which shifts in frequency with increasing amplitude. These phenomena are typical for a nonlinear vibrating system containing jumps. The main payback for the trainee is that the well-known Frequency Response Function (FRF) measurement of the mechanical system can also be used as an enabler for the nonlinear SI. The experiment shows the need for the quantification of nonlinear effects. Existing high return local linearization methods are introduced and applied directly to the system under test. The major advantage of these real experiments lies in the direct visual feedback provided to the user. A first presentation of the setup to test groups already involved in SI seems to indicate that the approach can strongly stimulate, motivate, attract and help potential users.
Book: Proceedings of the ISMA2014 International Conference on Noise and Vibration Engineering, Leuven (Belgium), Sept. 15-17, 2014
Pages: 3189-3202
Number of pages: 14
Publication year:2014
Keywords:low cost hardware-based demonstrator, system identification (SI) methods, self-paced training kit
  • ORCID: /0000-0003-0492-6137/work/83057161
  • ORCID: /0000-0003-2738-7914/work/69212322
  • Scopus Id: 84913616569