Amin Hammad

Multiobjective optimization of bridge deck rehabilitation using a genetic algorithm

The solution methods of multiobjective optimization have undergone constant development over the past three decades. However, the methods available to date are not particularly robust. Because of the complicated relationship between the rehabilitation cost and deterioration degree of infrastructure systems, it is difficult to find a near-optimal solution using common optimization methods. Since genetic algorithms work with a population of points, they can capture a number of solutions simultaneously and easily incorporate the concept of Pareto optimality. In this paper a simple genetic algorithm with two additional techniques, Pareto optimality ranking and fitness sharing, is implemented for the deck rehabilitation plan of network-level bridges, aiming to minimize the total rehabilitation cost and deterioration degree. This approach is illustrated by a simple example and then applied to a practical bridge system with a large number of bridges.

Improving lifting motion planning and re-planning of cranes with consideration for safety and efficiency

Safe and efficient operation of cranes requires not only good planning, but also sufficient and appropriate support in real time. Due to the dynamic nature of construction sites, unexpected changes in site layout may create new obstacles for the crane that can result in collisions and accidents. Previous research on construction equipment motion planning focuses on off-line support, which considers static environment or predictable obstacles. These plans may not fit the reality when the environment has any change. In this case on-site safety and efficiency can be affected. In this research, a motion planning algorithm is proposed to efficiently generate safe and smooth paths for crane motions while taking into account engineering constraints and the path quality. Path smoothness is taken into account to provide a realistic path for cranes and to reduce unnecessary movements. A dynamic motion planning algorithm is proposed to ensure safety during the execution stage by quickly re-planning and avoiding collisions. In addition, an anytime algorithm is proposed to search for better solutions during a given time period by improving path smoothness and by reducing path execution time. The proposed algorithms are compared with other available algorithms to evaluate their performance in terms of planning and re-planning time and the cost of the path. Based on the literature review, this is the first time that dual-tree RRT algorithms have been applied to crane motion planning.

Crane Pose Estimation Using UWB Real-Time Location System

AbstractOperating a crane is a complex job, which requires not only the experience of the operator, but also sufficient and appropriate real-time support to conceive and react to the environment. To help the crane operator, crane pose estimation is necessary to predict potential collisions. Environment perception technologies are essential to update environment information. Location data of the components of the cranes should be used to calculate the pose of the crane that can be used for collision avoidance. This paper aims to investigate how to collect and efficiently process the location data in near real time using ultra wideband (UWB) technology for providing intelligent support to crane operators. First, the requirements of using UWB technology in construction sites to track crane movements are defined. Then, the details of the UWB system setting method are investigated to decide the location of sensors and the number and location of tags attached to different components of a crane. A location data ...

Mobile model-based bridge lifecycle management system

Bridge lifecycle management systems are designed to assist in the performance of management functionalities related to bridges from the conceptual stage to the end of service life. This paper discusses the requirements for developing a mobile model-based bridge lifecycle management system (MMBLMS). This new system would link all the information about the lifecycle stages of a bridge (e.g., design, construction, inspection, and maintenance) to a four-dimensional model of the bridge, incorporating different scales of space and time to record events throughout the lifecycle with suitable levels of details (LoDs). In addition, the MMBLMS should support distributed databases and mobile location-based computing by providing user interfaces that can be used on mobile computers. A framework for a MMBLMS is described and the basic computational issues for realizing it are discussed, including the navigation modes, the picking behavior and the LoDs for representing bridge elements and defects. A prototype system developed in Java language is used to demonstrate the feasibility of the proposed methodology for realizing this system. A case study of a bridge in Montreal is also demonstrated. The prototype system received positive evaluations from bridge management engineers, and preliminary testing of the system and its user interface showed good results.

Distributed Augmented Reality for Visualizing Collaborative Construction Tasks

Augmented reality is a visualization method in which virtual objects are aligned with the real world and the viewer can interact with the virtual objects in real time. In this paper, a new methodology called distributed augmented reality for visualizing collaborative construction tasks (DARCC) is proposed. Using this methodology, virtual models of construction equipment can be operated and viewed by several operators to interactively simulate construction activities on the construction site in augmented reality mode. The paper investigates the design issues of DARCC including tracking and registration, object modeling, engineering constraints, and interaction and communication methods. The DARCC methodology is implemented in a prototype system and tested in a case study about a bridge deck rehabilitation project.

Localization of RFID-equipped assets during the operation phase of facilities

Indoor localization has gained importance as it has the potential to improve various processes related to the lifecycle management of facilities and to deliver personalized and location-based services (LBSs). Radio Frequency Identification (RFID) based systems, on the other hand, have been widely used in different applications in construction and maintenance. This paper investigates the usage of RFID technology for indoor localization of RFID equipped assets during the operation phase of facilities. The location-related data on RFID tags attached to assets are extracted from a Building Information Model (BIM) and can provide context-aware information inside the building which can improve Facilities Management (FM) processes. First, using the current location of the assets saved on the tags attached to fixed assets, an FM personnel is able to read tags from a distance and locate them on a floor plan. Fixed tags with known positions act as reference tags for RFID reader localization techniques. In this scenario, the user can also estimate his/her location by scanning the surrounding reference tags. Furthermore, the paper investigates an approach to locate moveable assets using received signals from available reference tags in the building based on pattern matching and clustering algorithms. As a result, a user equipped with an RFID reader is able to estimate his/her location, as well as the location of target assets, without having access to any Real-Time Location System (RTLS) infrastructure. Several case studies are used to demonstrate the feasibility of the proposed methods.

Near Real-Time Motion Planning and Simulation of Cranes in Construction: Framework and System Architecture

Motion planning of cranes is an important issue in construction projects, where rapid and accurate planning directly affects the safety and productivity of operations. The work presented in this paper is directed toward developing a framework for near real-time motion planning of cranes that satisfies safety requirements and efficiently considers the dynamic properties of construction sites. This framework is not aiming to full automation but rather for providing assistance to crane operators to replan safe paths in near real time. The proposed motion planning framework is designed in a way that makes it possible to be generalized over different types of equipment, and has the ability of visualizing and simulating motion planning results in near real-time. The framework is applied to develop a specialized motion planning system for construction equipment, Intelligent Construction Equipment Planner (ICE-Planner). This system is integrated into three-dimensional software to define, solve, and visualize moti...

Towards real-time simulation of construction activities considering spatio-temporal resolution requirements for improving safety and productivity

Traditional simulation models use statistical data to estimate task durations. However, to make the simulation results more realistic and reflecting the changes during the task execution, real-time simulation has been suggested by several researchers. On the other hand, little consideration is given to spatio-temporal constraints in simulation models. Several spatial modeling methods, such as maps, grids and 3D models, have been used in construction simulation. However, different resolutions of spatio-temporal representations should be used based on the specific requirements when considering spatio-temporal conflicts. The present paper aims to propose the basic concept of real-time simulation of construction activities considering spatio-temporal resolution requirements for improving safety and productivity. The objectives of the paper are: (1) to review real-time simulation methods of construction activities considering spatio-temporal conflicts; (2) to investigate the spatio-temporal requirements in the real-time simulation environment; and (3) to investigate the integration of simulation models at different spatio-temporal resolutions.

Multiagent Approach for Real-Time Collision Avoidance and Path Replanning for Cranes

AbstractCollisions on construction sites are one of the primary causes of fatal accidents. This paper proposes a multiagent-based approach to provide real-time support to the staff of construction projects. Collision avoidance is achieved by informing the crane operators about potential collisions and by providing motion replanning for crane operations. During the planning stage, a three-dimensional (3D) model of the static environment is created, and collision-free motion plans are generated by the agents for the cranes, considering engineering constraints and operation rules. During actual construction work, all mobile objects are tagged when entering the monitored area. A site state agent uses a real-time location system (RTLS), such as an ultra-wideband (UWB) system to collect location data, calculates the poses of the objects on site, and sends this information to other agents. By using this real-time updated information, agents can detect potential collisions and replan the path for the cranes for c...

Role-based access to facilities lifecycle information on RFID tags

Radio Frequency Identification (RFID) based systems have been used in different applications in the Architecture, Engineering, Construction, Owner and Operator (AECOO) industry. Applications are mainly designed for specific lifecycle stage of the facility and serve the needs of only one of the stakeholders. This would increase the cost and the labor for adding and removing tags and eliminate the chance of using shared resources. In this paper, the usage of tags permanently attached to components is proposed where the memory of the tags is used during the lifecycle by different stakeholders for data storage and handover. A Building Information Model (BIM) database is used for tackling the interoperability issues allowing different users to access and share the data. To securely and efficiently store data on RFID tags in ifcXML format, multi-level encryption together with role-based access control is applied on the data stored on RFID tags. Each user is assigned a certain role and can only access the part of data for which he has authorization according to a predefined role and the Access Control Policy. To explore the technical feasibility of the proposed approach, a case study considering both facilities management and emergency management has been implemented and tested at Concordia University.