A Wireless MEMS-Based Inclinometer Sensor Node for Structural Health Monitoring

Abstract

This paper proposes a wireless inclinometer sensor node for structural health monitoring (SHM) that can be applied to civil engineering and building structures subjected to various loadings. The inclinometer used in this study employs a method for calculating the tilt based on the difference between the static acceleration and the acceleration due to gravity, using a micro-electro-mechanical system (MEMS)-based accelerometer. A wireless sensor node was developed through which tilt measurement data are wirelessly transmitted to a monitoring server. This node consists of a slave node that uses a short-distance wireless communication system (RF 2.4 GHz) and a master node that uses a long-distance telecommunication system (code division multiple access—CDMA). The communication distance limitation, which is recognized as an important issue in wireless monitoring systems, has been resolved via these two wireless communication components. The reliability of the proposed wireless inclinometer sensor node was verified experimentally by comparing the values measured by the inclinometer and subsequently transferred to the monitoring server via wired and wireless transfer methods to permit a performance evaluation of the wireless communication sensor nodes. The experimental results indicated that the two systems (wired and wireless transfer systems) yielded almost identical values at a tilt angle greater than 1°, and a uniform difference was observed at a tilt angle less than 0.42° (approximately 0.0032° corresponding to 0.76% of the tilt angle, 0.42°) regardless of the tilt size. This result was deemed to be within the allowable range of measurement error in SHM. Thus, the wireless transfer system proposed in this study was experimentally verified for practical application in a structural health monitoring system.

High Precision Accelerometer with Integrated Thermal Sensor

“…Emerging applications require low bias instability (<10 μg), high resolution (<1 μg), miniature (<1 cm 3 ) and low power (<1 mW) accelerometers and allow a limited measurement range: wireless sensor network of Precision MEMS accelerometers based inclinometers dedicated to structural health monitoring (buildings, bridges, …) [1,2], wireless sensor networks of MEMS accelerometers based seismometers to detect and identify intruders in a protected area [3,4], inertial measurement units dedicated to micro UAVs. Although Vibrating Beam Accelerometers (VBA) have demonstrated good performances [5,6], actual accelerometers do not fulfill all these requirements, and are mainly limited by bias instability over temperature.…”

Portable and convenient cable force measurement using smartphone

“…Consequently, the traditional wired monitoring methods inevitably possess some shortcomings, such as large workload, slow, high cost, and multi-site constraints as well as requiring professional operators. In light of the challenges of the traditional methods, a low-power and multi-purpose wireless sensor technology has been proposed by many scholars [13][14][15][16][17][18]. However, the reliability of wireless data transmission between the sensor nodes and the base station is an issue that needs to be improved because it can result in data packet loss.…”

A low cost multi-sensor system for investigating the structural response of buildings

“…A multi-faceted network-based investigation for SHM, implementing an optimized strategy for damage detection in large structures, is provided in [Caffrey et al, 2004]. Examples of low cost SHM systems for bridges, buildings and structures based on wireless transmission systems and MEMS devices are shown in [Tan et al, 2011;Kumar and Bajpai, 2012;Ha et al, 2013]. A survey on wireless systems for the health monitoring of large structures is presented in [Wang and Liao, 2006].…”