Research
ShakeNet: A Tiered Wireless Accelerometer Network for Rapid Deployment in Civil Structures
Description
ShakeNet is a portable wireless sensor network for instrumenting large civil structures such as buildings, bridges, and dams. It consists of 40 sensor nodes each equipped with a 24-bit analog-to-digital conversion (ADC) board supporting triaxial MEMS accelerometers suitable for vibration sensing, an imote2 CPU board for wireless communication, and battery. The system comes preloaded with sensing software as well as deployment tools that will enable civil engineers to rapidly deploy the network. In addition to the sensors, the system contains up to 10 master-tier nodes that provide increased communications capacity.
What makes ShakeNet unique among wireless vibration networks is its software subsystem. The software is built upon Tenet, a programmable wireless sensing software architecture designed for tiered sensor networks. ShakeNet software is being developed by Govindan's group at USC's Embedded Networks Laboratory in the Dept. of Computer Sciences. ShakeNet will be field tested in a variety of structures including steel moment-frame and base-isolated reinforced concrete buildings, a large earth-and-rock-fill dam, and a steel truss bridge that contains a water distribution pipe. An earlier prototype was successfully tested on the 1500-ft-span, suspension cable Vincent Thomas Bridge in the Los Angeles harbor.
People
Monica Kohler, Department of Mechanical and Civil Engineering, Caltech
Ramesh Govindan, Department of Computer Sciences, USC
Nilesh Mishra, Department of Computer Sciences, USC
Shuai Hao, Department of Computer Sciences, USC
Bob Nigbor, Department of Civil and Environmental Engineering, UCLA
Laboratory Testing
Lab testing is being conducted at the USC Embedded Networks Lab in the Dept. of Computer Sciences and at the Caltech Dynamics Lab in the Dept. of Civil Engineering. Tests include
- Function generator input to ADC at fixed frequencies and amplitudes, and sweeps.
- Noise/ambient vibrations with and without sensor.
- Tilt tests of sensor components.
- Electrodynamic shake table input at fixed frequencies; comparison with colocated piezoelectric accelerometers. (0.1 Hz, 0.5 Hz, 0.8 Hz, 1.0 Hz, 1.2 Hz, 1.5 Hz, 2.0 Hz, 5.0 Hz, 10 Hz, 25 Hz, 45 Hz, 50 Hz, 90 Hz, 0.1 Hz rotated, 0.5 Hz rotated, 0.8 Hz rotated, 1.0 Hz rotated, 1.2 Hz rotated, 1.5 Hz rotated, 2.0 Hz rotated, 5.0 Hz rotated, 10.0 Hz rotated, 25.0 Hz rotated, 45.0 Hz rotated, 50.0 Hz rotated, 90.0 Hz rotated)
- Eccentric mass shaker loading from Millikan Library roof at frequencies between 1.0 Hz and 9 Hz; comparison with colocated Episensor accelerometers. (9th floor recordings) (Basement recordings)
Publications / Posters / Abstracts
- Mishra, N., S. Hao, R. Govindan, M. Kohler, and R. Nigbor, ShakeNet: A tiered wireless accelerometer network for rapid deployment in civil structures, Seismological Research Lett. (poster presented at SSA conference), April 23, 2010.
- Kohler, M., S. Hao, N. Mishra, R. Govindan, and R. Nigbor, ShakeNet: A tiered wireless accelerometer network for rapid deployment in civil structures, CENS Annual Research Review, Oct. 28, 2009.
