AMTS are advanced optical monitoring systems built around high-precision robotic total stations. The systems provide automated monitoring of deformation and settlement in structures and excavation support systems. Datasheet
AMTS at a project site in New York City
Precise Optical Monitoring
Precise optical monitoring requires total stations, prisms, and processing software. Total stations measure angles and distances to the prisms, which are fixed to critical points on the structure. The software applies statistically-weighted adjustments to the measurements and outputs spatial coordinates for each prism.
Changes in coordinates indicate that movement has occurred. The magnitude and direction of the movement is found by comparing current and initial coordinates.
In the past, precise optical monitoring was slow and expensive. That has changed with the development of AMTS (Automated Motorized Total Stations.
AMTS operate autonomously and can obtain frequent measurements 24/7.
Because the AMTS system is installed on structures and never moved, it provides measurement accuracy that is difficult to match with manual methods.
AMTS systems from GEO-Instruments include:
- Controllers that automate scheduling and recording of the observations.
- Wireless communications to transfer data to the internet.
- Automated least-squares processing to improve accuracy.
- Web-based reporting, which provides alarms, plots, and integration with standard geotechnical instrumentation.
Deployment involves installation of monitoring prisms at specified locations on the structure, control prisms at stable locations outside the zone of influence, and AMTS at locations that have clear line-of-sight to the prisms. Site-specific variations include specialized prisms, mounting brackets and towers, and solutions for power and communications.
GEO achieves superior results by installing redundant control prisms and configuring each network to include prisms from other networks. In addition, controllers are programmed to record three observations of each prism for each measurement cycle. These extra steps create strong geometric networks, enhance accuracy, and provide the flexibility to accommodate changes at the site.
Automated: Unattended operation improves safety, lowers costs, and provides data and alarms 24/7.
Accurate: Multiple observations and least-squares processing produce statistically robust data.
Reliable: Optical prisms have no electronics to fail and no cables that can be cut. Total stations monitor remotely, so they can be installed in secure locations, safe from accidental damage.
Compatible: GEO’s MonStar software can output data as specified by the customer, suitable to combine with other geotechnical instrumentation or for use with CAD-generated plan views and as-builts.
AMTS Flow Diagram
AMTS & Networked AMTS monitor the spatial position of both monitoring prisms and control prisms. “Networked” AMTS share several monitoring prisms, control prisms, and line of sight to each other.
Monitoring Prisms are installed on structures such as buildings, tunnel walls, bridge piers, railroad tracks, or pavement. Changes in the positions of monitoring prisms indicate movement of the structure.
Control Prisms are installed at stable locations outside the zone of influence. Measurements of control prisms are used to adjust for changes in the position of the AMTS itself.
Measurements & Processing
Each AMTS measurement cycle consists of multiple observations of all prisms. Afterwards, the measurements are transmitted offsite to GeoCloud servers for processing.
GeoCloud directs incoming AMTS measurements to Monstar and STAR*NET for quality checks and least-squares adjustments. Monstar then formats data for import into the GeoCloud project database.
The import process checks for missing data, tests measurements against alarm thresholds, and then stores measurements in the project database. Planviews, trend plots, and reports are made available on the project website.
Primary & Secondary Control
AMTS measurements can be referenced to the project coordinate framework through primary and secondary control points.
Primary Control refers to the physical markers of the project coordinate framework, typically bronze disks set into stable structures outside the zone of influence. Primary control points have known coordinates, but may not be intervisible with the AMTS.
To provide points with known coordinates that are accessible to the AMTS, a network of secondary control points is established. Control prisms installed at these secondary control points then tie AMTS measurements to the project coordinate framework.