An adaptive polynomial based forward prediction algorithm for multi-actuator real-time dynamic substructuring

Abstract

ReuseUnless indicated otherwise, fulltext items are protected by copyright with all rights reserved. The copyright exception in section 29 of the Copyright, Designs and Patents Act 1988 allows the making of a single copy solely for the purpose of non-commercial research or private study within the limits of fair dealing. The publisher or other rights-holder may allow further reproduction and re-use of this version -refer to the White Rose Research Online record for this item. Where records identify the publisher as the copyright holder, users can verify any specific terms of use on the publisher's website. TakedownIf you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing eprints@whiterose.ac.uk including the URL of the record and the reason for the withdrawal request. Real-time dynamic substructuring is a novel experimental technique used to test the dynamic behaviour of complex structures. The technique involves creating a hybrid model of the entire structure by combining an experimental test piece -the substructure -with a set of numerical models. In this paper we describe a multi-actuator substructured system of a coupled three mass-spring-damper system and use this to demonstrate the nature of delay errors which can first lead to a loss of accuracy and then to instability of the substructuring algorithm.Synchronisation theory and delay compensation are used to show how the delay errors, present in the transfer systems, can be minimised by online forward prediction. This new algorithm uses a more generic approach than the single step algorithms applied to substructuring thus far, giving considerable advantages in terms of flexibility and accuracy. The basic algorithm is then extended by closing the control loop resulting in an error driven adaptive feedback controller which can operate with no prior knowledge of the plant dynamics. The adaptive algorithm is then used to perform a real substructuring test using experimentally measured forces to deliver a stable substructuring algorithm.

Emulator-based control for actuator-based hardware-in-the-loop testing

“…This small phase margin gives rise to the extreme sensitivity problem discussed elsewhere (Gawthrop et al, 2005b(Gawthrop et al, , 2006Wallace et al, 2005b); in particular, a small value of c together with neglected dynamics in the transfer system results in…”

Robust real-time substructuring techniques for under-damped systems

“…The adaptive nature of the outer-loop controllers proposed in [2,8,12] allow for the compensation of the transfer system dynamics despite uncertainty in the transfer function model derived in step 2. Although they incorporate some level of robustness due to this adaptation, they do not explicitly include the robustness compensator proposed in step 4.…”

“…Darby et al [2] relaxed the assumption of a pure delay by developing a forward prediction method that varied the amount of delay compensation, based on the error between the actuator displacement and the desired numerical model displacement. This method was extended by Wallace et al [12] who developed an adaptive forward prediction algorithm that used variable polynomial coefficients such that non-integer multiples of the previous time step could be predicted and also incorporates an amplitude correction algorithm. The use of a Smith predictor has also been proposed as a suitable delay compensator [9].…”

Real-time dynamic hybrid testing for soil–structure interaction analysis

“…To address the problem of inevitable time delay in hydraulic servo system (Horiuchi et al 1999), the calculated displacement u (t+ t) is predicted forward as ( ) u t t ′ + Δ using a delay compensation method. In this paper, the compensation method developed by Wallace et al (2005) is used to compensate for the time delay, which is about 10 ms in this system. After that, the shaking-table is driven by the predicted command ( ) u t t ′ + Δ and the superstructure model vibrates under the excitation.…”