Magdy Ibrahim

Experimental Study of Wireless Sensor Networks forIndoor Construction Operations

Emerging wireless sensor networks (WSN) technology offers a great potential in supporting current project management practices. Deploying wireless sensor networks on construction sites can lead to significant time and cost savings by providing accurate and near-real-time data to project management personnel. Continuous monitoring of labor usage, materials placement and equipment performance provides valuable data for assessing progress of construction operations and assists in improving safety and security on job sites. Construction activities take place in outdoor and indoor environments, while Global Positioning System (GPS) is ideal solution for tracking outdoor activities; it is not applicable for indoor application due to the lack of line-of-sight to satellites signals. Therefore, GPS-less means of tracking is required in indoor environments. While several research efforts had been attempted to develop indoor positioning systems utilizing various wireless technologies, there is no clear understanding of which wireless technology performs better in indoor construction environment. This research aims to experiment and test wireless technologies to aid the selection of wireless sensor networks configuration in support of current practice of progress tracking at construction on job sites. This paper describes experimental study conducted to determine the effectiveness of wireless technologies for dynamic indoor resource position tracking. The experiments investigate the challenges of wireless technologies applications in indoor environments, in particular, Wireless Local Area Networks (WLAN), Bluetooth, Zigbee and Synapse SNAP. A total of 21 experiments were carried out and 1752 data sets were analyzed. The results showed that Synapse SNAP out-performed all other technologies. The findings of this study are expected to provide a reference for future research on selection of indoor positioning technologies.

IMU-Based Indoor Localization for Construction Applications

Localization and tracking of resources on construction jobsites is an emerging area where the location of materials, labour, and equipment is used to estimate productivity, measure projects progress and/or enhance jobsite safety. GPS has been widely used for outdoor tracking of construction operations. However, GPS is not suitable for indoor applications due to the lack of signal coverage; particularly inside tunnels or buildings. Several indoor localization research had been attempted, however such developments rely heavily on extensive external communication network infrastructures. These developments also are susceptible to electromagnetic interference in noisy construction jobsites. This paper presents indoor localization system using a microcontroller equipped with an inertial measurement unit (IMU). The IMU contains a cluster of sensors: accelerometer, gyroscope and magnetometer. The microcontroller uses a direct cosine matrix algorithm to fuse sensors data and calculate non-gravitational acceleration using ninedegrees-of-freedom motion equations. Current position is calculated based on measured acceleration and heading, while accounting for growing error in speed estimation utilizing jerk integration algorithm. Experimental results are presented to illustrate the relative effectiveness of the developed system, which is able to operate independently of any external aids and visibility conditions.

Self-calibrated WSN for indoor tracing and control of construction operations

Effective tracking and timely progress reporting are essential for successful delivery of construction projects. In this respect, several research attempts have been made to identify and track the locations of material, equipment and labor on construction Jobsites using wireless sensing technologies. Such developed methods utilize radio signal propagation models to estimate location based on measured received signal strength (RSSI). However, radio signal propagation models are highly dependent on the surrounding environment. As well, these methods are susceptible to interferences caused by metallic structures and obstacles, which are continually changing location on highly dynamic construction jobsites. This paper presents fundamental research work, designed to study the beneficial effect of self-calibrated wireless sensor network (SC-WSN) for higher accuracy of indoor localization. The developed SC-WSN hardware consists of fixed gateway unites mounted at predefined locations and mobile unites mounted on tracked objects. The designed network estimates a tagged object location based on its measured signal strength, which is then converted to corresponding distance using a dynamic signal propagation model. The developed dynamic model calibrates its parameters periodically to minimize errors in its estimated locations using particle swarm optimization algorithm. Experimental results are presented to illustrate the relative effectiveness of the developed system in comparison to commonly used fixed propagation systems.

Automated Development of Construction Schedules Using Onsite Data Acquisition

Detailed as-built project schedules are necessary to close out construction projects, benchmarking, forecasting, dispute resolution, and improving cost estimates of future projects. Manual procedures for developments of as-built documentation is time consuming, involves numerous interfaces and human interventions. This paper presents computational framework that encompasses automated site data acquisition and generates schedule updates utilizing commercially available project scheduling software. The work is carried out collaboratively with a Hydro Quebec team. The site data is captured employing mobile computing using iPad® type computers and Wi-Fi. The information is directly compiled in a centralized database server. The synchronization tool is a bi-directional application and is used on servers to communicate with iPad® computers deployed onsite. The captured data is stored in Microsoft SQL® relation database that consists of 63 entities. Computer software application has been developed in Microsoft Visual Basic® (vb.net) environment for extracting the collected site data, linking the database to the as planned schedule, and generating the actual, also known as as-built schedule. The development can be utilized in automated progress reporting, evaluating future bids, generating master schedules and a wide range of efficient EVM applications.