# A Tilt Sensor Node Embedding a Data-Fusion Algorithm for Vibration-Based SHM

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## Abstract

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## 1. Introduction

## 2. Materials and Methods

#### 2.1. Sensor Node

#### 2.2. Sensor Data Fusion

#### 2.3. Algorithm Definition

#### 2.4. Embedded Processing

## 3. System test and Discussion

#### 3.1. System Validation in Static Condition

#### 3.2. Vibration Analysis

## 4. Conclusions

## Author Contributions

## Funding

## Conflicts of Interest

## References

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**Figure 1.**Hardware instrumentation: (

**a**) Schematic diagram of the sensor node and (

**b**) its relative prototype inside an ad-hoc case.

**Figure 2.**Geometric relation between tilt angles and acceleration referred to z-direction for a device installed on the top of a structure.

**Figure 4.**Window function implemented to diminish the computational burden of the data fusion algorithm working on sensor: (

**a**) Time-domain working principle of the OLA mechanism and (

**b**) window spectral properties for overlapping fraction spanning in the interval [0.1; 0.5].

**Figure 5.**(

**a**) Optimal cutoff frequency estimation and (

**b**) effect of the cutoff frequency selection on OLA sensor data fusion (actual tilt value: 30°).

**Figure 6.**Experimental setup in pseudo-static conditions: anti-vibration table equipped with TUV level.

**Figure 8.**Comparison of spectra resulting from the windowed and non-windowed approach with respect to the spectral content of radial acceleration.

**Figure 9.**Spectral analysis on tilt values extracted by sensor node S2: comparison of the error distribution in vibrating modes extraction from acceleration and tilt signals via FFT and Welch strategy.

**Figure 10.**Comparison of spectral density characteristics of tilt signals estimated via FFT elaboration by nodes located at different positions.

**Table 1.**Statistics obtained from measurements in different pseudo-static configurations: mean value, relative error and standard deviation.

Reference Tilt | Measured Tilt | ${\mathit{E}}_{\mathit{r}}$ | $\mathit{\sigma}$ |
---|---|---|---|

[°] | [°] | [%] | [°] |

30 | 30.1832 | 0.611 | 0.1399 |

45 | 45.0024 | 0.005 | 0.1523 |

60 | 60.3116 | 0.519 | 0.1985 |

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**MDPI and ACS Style**

Testoni, N.; Zonzini, F.; Marzani, A.; Scarponi, V.; De Marchi, L.
A Tilt Sensor Node Embedding a Data-Fusion Algorithm for Vibration-Based SHM. *Electronics* **2019**, *8*, 45.
https://doi.org/10.3390/electronics8010045

**AMA Style**

Testoni N, Zonzini F, Marzani A, Scarponi V, De Marchi L.
A Tilt Sensor Node Embedding a Data-Fusion Algorithm for Vibration-Based SHM. *Electronics*. 2019; 8(1):45.
https://doi.org/10.3390/electronics8010045

**Chicago/Turabian Style**

Testoni, Nicola, Federica Zonzini, Alessandro Marzani, Valentina Scarponi, and Luca De Marchi.
2019. "A Tilt Sensor Node Embedding a Data-Fusion Algorithm for Vibration-Based SHM" *Electronics* 8, no. 1: 45.
https://doi.org/10.3390/electronics8010045