Online Structural Health Monitoring and Parameter Estimation for Vibrating Active Cantilever Beams Using Low-Priced Microcontrollers

Gergely Takács,Ján Vachálek,Boris Rohal’-Ilkiv

doi:10.1155/2015/506430

Gergely Takács, Ján Vachálek + Show 1 more

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https://doi.org/10.1155/2015/506430

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Abstract

This paper presents a structural health monitoring and parameter estimation system for vibrating active cantilever beams using low-cost embedded computing hardware. The actuator input and the measured position are used in an augmented nonlinear model to observe the dynamic states and parameters of the beam by the continuous-discrete extended Kalman filter (EKF). The presence of undesirable structural change is detected by variations of the first resonance estimate computed from the observed equivalent mass, stiffness, damping, and voltage-force conversion coefficients. A fault signal is generated upon its departure from a predetermined nominal tolerance band. The algorithm is implemented using automatically generated and deployed machine code on an electronics prototyping platform, featuring an economically feasible 8-bit microcontroller unit (MCU). The validation experiments demonstrate the viability of the proposed system to detect sudden or gradual mechanical changes in real-time, while the functionality on low-cost miniaturized hardware suggests a strong potential for mass-production and structural integration. The modest computing power of the microcontroller and automated code generation designates the proposed system only for very flexible structures, with a first dominant resonant frequency under 4 Hz; however, a code-optimized version certainly allows much stiffer structures or more complicated models on the same hardware.

Highlights

Recent engineering trends foreshadow a tendency, where mechanical structures are becoming more vibration prone
Microcontroller units (MCU) are essentially miniaturized computing platforms that are capable of independent operation and pose the built in peripherals necessary to read sensors or drive actuators
The PRBS input signal is supplied constantly, regardless of the change. Both dynamic state estimates start from the common initial state of x0+ = [0 0]T, shown as black triangles in the figure

Summary

Introduction

Recent engineering trends foreshadow a tendency, where mechanical structures are becoming more vibration prone. Aircraft wing surfaces with progressive design may benefit from reduced fuel and maintenance costs or increased maneuverability, while robotic arms and manipulators are faced with increasing demands on working speeds Often, these improvements are plagued by the curse of lowered stiffness and a susceptibility to demonstrate undesired vibration response. Microcontroller units (MCU) are essentially miniaturized computing platforms that are capable of independent operation and pose the built in peripherals necessary to read sensors or drive actuators As both the price and the size of MCUs are decreasing [3], it is possible to integrate vibration control and diagnostics systems into mechanical structures on a mass produced scale, even with the possibility to use several detached systems in a decentralized manner

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