| dc.description.abstract | Nowadays, most bridge health and safety inspections are still wired
transmissions, and only a single or a small number of bridge components
are inspected simultaneously. The detection of all bridge components
requires the movement of a large number of equipment, the installation of
several wired detection instruments, and the structure of multiple wired
inspection instruments, which is quite time-consuming. Therefore, this
research has developed a low-power wireless vibration sensing device,
which includes a micro control unit (MCU), a high-precision adxl355
acceleration meter to measure the acceleration of steel cable, and a Lora
(Long range) as a wireless transmission module and SD card module to
store experimental data. The volume of this instrument is about
15cm*10cm*5cm, which is convenient to carry and easy to install on steel
cables. The operating mode is that the system will maintain a standby state.
When the user sends the detection command, the system starts to detect the
vibration on the steel cable. Through measuring the diachronic acceleration
data of the steel cable, performing a fast Fourier transform (FFT), and
running the self-developed algorithm to calculate the vibration frequency
of the steel cable, the eigenfrequency is transmitted back to the user
through automatic operation and wireless transmission, and the user can
calculate the cable tension based on string theory. In terms of software, this
study overcomes the problems of insufficient memory in the
microcontroller, which affects the amount of fast Fourier transform data,
and the need to sample and store acceleration data simultaneously in a
single core CPU. In the eigenfrequency algorithm part, the accuracy of theiv
eigenfrequency output is simultaneously experimental results that prove
the system’s feasibility. The measurement and calculation are completed at
the sensing node, and the eigenfrequency is transmitted back to the user by
a wireless transmission system that saves time and effort. | en_US |