Passivity control for nonlinear real-time hybrid tests

Ld Hashan Peiris,Jonathan L Du Bois,Andrew R Plummer

doi:10.1177/0959651820959003

Ld Hashan Peiris, Jonathan L Du Bois + Show 1 more

Open Access

https://doi.org/10.1177/0959651820959003

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Abstract

In real-time hybrid testing, systems are separated into a numerically simulated substructure and a physically tested substructure, coupled in real time using actuators and force sensors. Actuators tend to introduce spurious dynamics to the system which can result in inaccuracy or even instability. Conventional means of mitigating these dynamics can be ineffective in the presence of nonlinearity in the physical substructure or transfer system. This article presents the first experimental tests of a novel passivity-based controller for hybrid testing. Passivity control was found to stabilize a real-time hybrid test which would otherwise exhibit instability due to the combination of actuator lag and a stiff physical substructure. Limit cycle behaviour caused by nonlinear friction in the actuator was also reduced by 95% with passivity control, compared to only 64% for contemporary methods. The combination of passivity control with conventional methods is shown to reduce actuator lag from 35.3° to 13.7°. A big advantage of passivity control is its simplicity compared with model-based compensators, making it an attractive choice in a wide range of contexts.

Highlights

Real-time hybrid testing (RtHT) is a method of analysing complex systems utilizing a combination of experimental and simulation-based techniques
The open loop transfer function of the hybrid test is evaluated using the transfer functions of the numerical substructure, actuator and the physical substructure linearized for a range of physical substructure stiffnesses
This article demonstrates the first application of passivity control to the stabilization of an RtHT

Summary

Introduction

Real-time hybrid testing (RtHT) is a method of analysing complex systems utilizing a combination of experimental and simulation-based techniques. In order to compare the performance of passivity control with a state-of-the-art compensation scheme, a second-order lag compensator as utilized in du Bois et al.[5] is designed to mitigate the transfer dynamics of the actuator in the presence of the physical substructure.

Results

Conclusion