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In decades, the conventional construction industry has been considered as a labour-intensive, low-tech industry with low productivity. It seems construction sector has been left behind by technologies innovations and sciences developments that have already reshaped many other industrial sectors. Construction industry facing challenges to responds to change technical, economic and social conditions, there is an increasing need of changing construction technique, communication and management strategy within the sector.
Mass production and automation was introduced in the early twentieth century. It was a method of producing products in large quantities with relatively low cost. The product were produced in many different components and assembled into a finish product through an assembly line, the approach of this method has reshaped manufacturing industry especially in the sector of automobile, aircraft, train etc. it has proved that automation is the key to increase productivity.
Industrialized construction (modular, panelised, sub-assemblies etc.) became popular during the post-war period, due to the huge demand in housing. Because of the nature of the concept, instead of adopting automation technology to traditional construction methods, there is a potential opportunity to integrate and apply manufacturing technology to enable a revolutionary change in construction sector in terms of design, production and management.
The aim of this paper intends to discover and recognise the opportunities and challenges that advanced technology and modern manufacturing process offer to the industrialized construction sector, and how would the sector to embrace automation and enhance the way its operate, along with the introduce of a integrated management system from manufacturing industry. The paper will also provide an overview of the issues and difficulties the industry will face during introducing new technology innovations and adopting advanced automated production process into construction sector.
Challenges emerged and changes need to be made within construction sector due to the changes in global phenomenon, economic, science and technology.
There is a need for construction industry to improve its productivity, quality and flexibility, along with requirement to adapt technologies and management methods of other manufacturing industry.
The formation of off-site construction sector has the advantages to adapting technologies directly from manufacturing sectors which support the principles of mass production and customization. Off-site construction methods can easily provide an efficient design and management process to allow customized products at mass production prices with a better quality, so that an entire building will be no longer constructed with conventional methods but to be produced as a product.
There are numerous advantages of using off-site construction methods.
As the production process is carried out in a factory environment which provides better communication between clients, designers and engineers, to ensure high quality standards, increase the speed of production as well as minimise impact on the environment by eliminating wastes. In recent years, there is a growing interest in the area of adopting automation technologies to construction and many building systems have been developed by implementing robotic technology to assist both on-site and off-site activities.
The principle of future automated construction is to create a highly efficient automated system and to produce a customer orientated product, which involves apply advanced technologies both off-site and on-site, new design methods will be launched to develop of a new building systems, customized software and different management approach will be integrated in manufacturing process. Development of integrated construction automation and robotics building processes will assist component producing process and onsite construction. Life cycle of a building will be increased by use of new materials and new definition of building construction.
However, in order to optimise the use of automated construction methods, it is important that design concept is compatible with technology available. It is necessary that research and development (R&D) sector plays a very important role in terms of select and discover available approach for manufacturing methods. While designers and engineers need to apply the concept of automation whereby adjusting the design to fit production as a result the structural, functional, and the flexibility of the building could be implemented.
Under one roof
Design method evolution
The goal of Industrialised building construction is to establish a new method of producing a per-engineered product rather than building in conventional method. Finished design is completed by a group of assembled components. A building will be no longer to be designed as a whole but developed as a range of components and accessories. The changing of design process results in the changes of practices.
Traditional building design methods will be challenged by automated design methods. From the success of other manufacture industry has shown the benefit of using automated production methods. Building product development stage will be a systematic process; building system will be designed with flexibility of using robotic erection. Compare to conventional method, Designers will be increasingly relying on using CAD system and assisted with other technologies such as virtual reality system (VR). Virtual reality system creates a computer- simulated environment, which enables a physical presence, interaction with real environment. Client assisted by the system enable the simulation of the design process. An on-line virtual tool provides a selection of components; simulate real-time designing and environment, then client can import selected 3D design elements such as window, doors, roof into the system, to enable designer to gain a good perception of the project, the use of computer simulated tool in conjunction with automated data collection tool to schedule and manage the project. The cost, design, material usage and assembling specification of the project can be generated automatically.
In the past two decade, Automobile industry has benefited from using Computer Integrated Manufacturing (CIM) the system has not only changed the productivity of automobile manufacturing but also defined the concept of customer oriented product concept. While the construction industry still based on labour intense type of work, there is a need for automating building process, thus an improved productivity, quality and better working environment could be achieved.
Overview of Industrialised building system (mainly on residential housing sector)
Nowadays, with housing stock market reaches highest demands in many countries, take UK for example, government aiming to build 50,000 units a year to fill the gap, however, if just rely on conventional methods this target is unlikely to meet. Thus, sustainable and modern design approaches became more and more crucial. Highly industrialized building method (modular, panelised, sub-assemblies etc.) has been wildly accepted and recommended. Factory manufactured homes (prefab homes) are transported on site sim-finished, which may only take days or even hours to complete, while in traditional construction method, homes are built from tons of basic materials using on-site labor and technique, which cost more and take longer to finish build. Advanced technology and automation in manufacturing industry has set up a successful example to construction industry. Due to the uniqueness of construction process, it is difficult to adopt automation techniques from other manufacturing sector directly. The advanced manufacturing methods which chosen have to be amended then integrated gradually into construction process.
Compared with traditional methods of construction, the advantages that prefab offers shown as below:
Reduce labor costs, for example, to build a small family house in England, client expect to pay up to £250 a day to cover contractors and builder's cost, this not even including costs of materials and equipments, also weather condition could effect on speed of on-site construction, as in extremely cold or damp condition, mortar will take longer to set due to frost, and one coat of plaster could take up to a day to set, this will slow down speed of construction dramatically and increase costs of labour. In comparison, off-site construction has most of their role carried out in factory environment with tight quality control and completely weather proof, specialist worker will produce building components at maximum efficiency.
Reduce material costs; normally, client or contractor will have to set up an account with local building merchants and price charged is depending on the amount of material purchased. On the other hand, off-site manufactures whose order certain material in bulk directly from suppliers will normally receive better prices.
Environmental friendly, as most components is produced off-site and ready for on-site assembly, it will reduce the amount of waste during on-site construction, Many prefab components are made of recyclable material and the building is to be designed more energy efficient.
Prefab building is not something new, but it was once re-homed tens of thousands families in Britain after the Second World War. However after decades, prefab housing has not been as marketable as traditional housing. There are numbers of barriers and disadvantages of using such system have also occurred in several cases.
Design limitations, while a prefab wall component are designed for a flat roof to sit on, and then it is unsuitable for it to be adapted for a different roof design.
Components are manufactured in huge quantity, if there is a fault appeared on one, and then the same issue could be found on all. This could lead to unnecessary time waste.
Lack of individuality, has shown on many post-war off-site designs. Even today, most off-site designed home is virtually same as traditionally built house, they are often been treated as lower-grade or temporary shelter by the general public.
Skill shortage, builders and contractors are not familiar with the system, so on-site assembly will be carried out by factory engineers and specially trained labor, this would reduce the need of employ local contractors and cost local labor market.
Despite the disadvantages of modular system, industrialized construction attribute vast numbers of benefits, there is a potential opportunity of future prefab building industry to adopt advantages and reassess the disadvantages , developing new prefab techniques and materials to provide a better performed building system.
Prefab System Performance
In many countries, such as Japan, Germany, manufacturers are reinventing the process of home construction by adopting assembly line automation methods to achieve mass production. A number of new construction materials are starting to be used as components in prefab housing. Such as, structural insulated panels (SIPs) and insulating concrete forms (ICFs). There are systems developed by using prefab technique, include prefab foundation systems, steel framing, concrete framing, large-modular systems, and so on.
Prefab Foundation system
Due to different site condition, different Materials, drainage system and engineered structural support could be applied. Initially, in house designers and engineer teams will exam soil type, contamination hazards of the site, and other critical natural elements of the given location, such as flood hazard zone, or seismic area, once all data is collected and appropriate system will be finalized, the chosen system needs to be designed subject to local building regulation requirement and to be reviewed by local authorities over construction period both off-site and on-site. The system is designed and manufactured as prefabricated components with consideration of drainage system used and complete integrated service installation points. Furthermore, according to different type of floor chassis system used, connection devise and method maybe vary, such as direct fastening system, direct bolting system, or welding system. Once the site is ready, the foundation components will be delivered onsite and drop in to the footing or trenches while connecting with service point.
Panelised Wall & Floor and Roof systems
Panels can be produced in an automated factory environment, using computer program that transfers panel-cutting instructions directly from digital CAD (computer aided design) drawings. The finished product will be inspected and then transport on to jobsite.
There are many types of panelised system available, such as light gauge steel, insulating concrete forms (ICFs), aluminum concrete and fiberglass components. They are consist of pre-engineered panels, factory manufactured, that will be erected on site to form a structural envelop. The most common, Structural insulated panel (SIPs) which consist of an insulating layer of rigid polymer foam sandwiched between two layers of structural board, offering superior insulation, structural capacity. SIPs are durable, light in weight and dimensionally stable. The system will significantly simplify on-site farming and reduce the risk of health and safety issues occurred from on-site construction. Compare with other modular system, SIPs provide more flexibility in terms of design, complicated shapes can be produced with considerably low price. Structurally, SIPs wall panel is deceptively strong, which could perform as load-bearing wall, roof structure, as well as internal dividing wall. Due to the exceptional load-bearing performance of the wall panel means variety of floor systems could be utilized. Compare with conventional wood framing technique, SIPs offer a dense, uniform and continuous air barrier with few thermal bridges, and little opportunity for internal convection, therefore less air leaks and reduce condensation occurred by cold bridging.
Eco-joists are one of the best flooring system for SIPs structure, they are consist of parallel stress grade timber overhangs connected with "V" shaped galvanised steel webs. They share the same advantages as SIPs, they are pre engineered, designed and manufactured according to deferent loads requested by the project. The systems are lightweight and easy to handle on site, in addition all services such as electrical cables and waste pipes and ventilation dust could easily install between the open webs. Meanwhile, roof construction could achieve maximum useable space by using SIPs, because there will be no requirement of roof trusses going across loft space, and it offers continuous insulation to increase energy performance. As a result, combination of these two systems provides an excellent sample of advantages of using prefabricated components in modern construction.
Lifecycle of the Prefab system
Product orientated design
Firstly, building will be marketed as a product rather than a traditional building. To be able produce them in large quantities with relatively low cost, the key is to mass produce, but with infinite personal taste, the combination of mass production and personal taste is mass customization, to give customer choices but within a manageable range. This will keep manufacturing processes sample and economies of scale can be implemented. For example, car manufacturers allow customer to choose the colour and certain specifications of a car model. However, customers are unable to specify the colour of the steering wheel, and design of the seats, even if it is achievable.
Future prefab system will be designed to be more flexible; while components can be mountable and de-mountable for reuse. Proposed building site will be assisted by construction robots with little human intervention on site. The development of prefabrication in construction sector has demonstrated it is possible to adopt manufacturing technique into construction process and to achieve automation. Prefab building process will adopt an automated system in terms of, design, engineering, and construction, which means future construction process will proceed in an automated manner. For example, customer could pick different colours of wall finish and flooring or kitchen and bathroom pods from a product catalogue to fit into a standard floor plan, just like buying a car with choices of different body paint and interior accessories. The main building components will be mass produced such as wall and floor panels, and accessories such as different designs of kitchen pods to be produced only when ordered, to allow parts arrive into production just when needed.
A new joining, and installation method will be developed with consideration of later on-site installation; building component will operate systemically as well as interchangeable to maximize system performance and lifespan. While on-site, construction robots will perform multiple tasks to cope with variety of site conditions, robots will have sequence or digital controlled. Construction robots will interact with each other on-site; identify issues and automatically response to site personal such as, project manager. In case of technical failures, all building activities should be able to handle by works manually.
The house has been designed flexible and adaptable to allow future alteration. To alter existing house, traditionally, clients have to seek professional help to carry out the building work or relocated to a different property. In contrast, due to the way that house been constructed, the internal and structural wall, roof and floor can be easily disassembly from existing structure and proposed components will be "plug-in" to form an improved floor layout or provide an additional accommodation to suit client's requirement. The dealer will provide data from their database to cover information from the time of construction on the materials used, floor plans, piping and electrical lines, etc. Client then can use these specifications to obtain quotations from the dealer or other service providers. Site visit and inspection will be carried out by the selected manufacturer, data collected and design requirements of the project will be incorporated by computer integrated construction (CIC) system, design specification and cost will be produced pro manufacturing. The fully automated construction process shall precede pro to the final approval from the client.
Second hand housing market and renovation market will be fulfilled with a new definition, second hand house will be put on the market and buyer is no longer necessarily to relocate to where the house is. Second hand house will be dissembled and transported back to the factory for inspection and renewal; inspected components are finished off with new fittings and equipments. The building components will be transported to the new site, by using the same technique, the building will be reassembled and ready for the new owner to move in. The same concept also applied on to those clients who extremely emotionally touched with their beloved home, instead of ditch the old one, alternatively the house could be relocated wherever they go.
The efficient, flexible and mass production concept of future prefab industry enable a niche market to emerge within the construction sector; a prefab house will be affordable to purchase but offer high degree of design, flexibility. Customer will engage in the design process which will give the project their personal taste, incorporate with the mythology of mass customization, and offer customer with more choices. The lifecycle of a building could be extended longer by reclaim and disassembly the existing structure. In addition, the future prefab industry has the potential to achieve automation in all construction phases.
Strategy & action of Future Prefab construction
For achieving the requirement of prefab building mass production, all components need to be standardized for production. Similar to automobile industries, same parts might be produced and used on fabricate different model, consequently, materials can be utilized in the most efficient manner to produce wide range of standardized components, such as universal wall, floor and roof system. Then the usage of same production process, machinery, and skilled workers can be maximized then maximum productivity achieved.
Mass production and standardized product allow a high degree of labor specialization with the production process. It is an opportunity to use single task robots to conduct specific rule repetitiously. In such working condition, automated technology could be applied and tested within the prefab construction sector.
In order to obtain an optimal result, a high degree of coordination must exist between various relevant parties such as designer, manufacturer, owner, and contractor. This is achieved through an integrated system in which all these functions are performed under a unified authority (1)
Automation in future prefab construction industry
Robotic industrial applications are very well established in the manufacturing industry, while there is a very limited influence on the construction sector. A number of benefits are anticipated from these automated systems, including improved construction productivity, to eliminate the dependence on labor, and improved safety and quality. The impact of this integrated automation approach is expected to be significant due to its high level of management between resources and processes, and well defined environment for information transfer. As a follow-up to this effort, several research issues need to be considered, including the design of materials handling systems which will maintain the efficiency of the automated building construction approach. In Japan, the success of the automobile industry's automated assembly plants, combined with the construction industry's worker shortage, has helped encourage the development of Japan's automated and robotic construction operations. Although the trend toward automation itself has produced some gains in productivity, the primary goal is to do a specific task with fewer people in a safer environment. (2) The need for automation in construction is clear; as most construction activities are repetitious, labor-intensive, and dangerous so that it is perfectly suitable for robot automation.
T. Bock (2007) illustrated a robotic precast concrete panel factory that uses a multipurpose unit which allows flexible production of the concrete floor, wall and roof panels. Here, according to certain CAD data, a multi functional gantry type robotic unit with two vertical arms places magnetos on the steel production table. The unit also attaches shutters on top of the magneto and then places horizontal, vertical and triangular reinforcement bars, as per design. A CAD-CAM controlled concrete distributor spreads the right amount of concrete while controlled by a CAD layout plan, which takes into account installation, window or door opening. (3)
Swedish company Randek has developed a number of high-performance position controlled systems for prefab house manufacturing. Those systems were developed similar to the manufacturing industry and were intended to perform routine task in on location. For instance, their latest wall, floor and roof production line system SF021 is developed to be a flexible system for effective production of insulated wall elements. Firstly, a framework is built with studs and top and bottom plates installed by using a CAD-CAM controlled nailing gun, and then wall sheet will be nailed in while the whole wall component is flipped over and ready for the next work station. Second step, the wall component will be insulated. The final stage, the insulated wall will be flipped upside down and another wall sheet to be nailed on to seal up the component. The wall component is completed and ready for site delivery. The whole process is computer controlled, and it is only require 3-4 operators to over see the operation.
In Japan, there are more than 85 present of the houses are prefabricated, several leading construction firms have developed fully automated system for manufacturing building components, such as Sekisui chemical, robots has played active roles at the production line. Robotic manipulators were used as assistants to human. This approach allows the robot to be less autonomous and technically simpler, needing only limited sensing abilities. According to this approach, the human performs the vital parts of the task, and the robot is used to expand the human physical limits. Such systems, of less autonomous performance, can be more easily adapted for assistance in a variety of building tasks.
(4) Off-site production sequence may have successfully adopted automation concept, robots are capable of conduct many factory based roles such as handing heavy materials, and it has benefited construction industry greatly. On the other hand, robots still face many difficulties due to the dynamic nature of construction site and economical challenge. Construction industry has a variety combination of sectors and it has to cope with variety of circumstances on each project and site. In construction automation, the building also serves simultaneously as the work environment. Construction robots will face great challenges when cope with complexity of on-site tasks.
To tackle this, single-task robots need to be designed not only to assist human but also interact with human and enhance the over all performance; robots with specific function will be programmed to work independently, such as on-site single-task robots will perform most of the assembling and heavy lifting roles, as well as problem solving and data collection roles. Single-task robots been designed for a factory systematic environment free-standing robots will be moving along a production line on wheels to complete production roles. While suspended robots usually have lifting mechanisms to help it move up and down.
Mobile Robotic system also developed for material handing on-site. Personal interior finishing robot is developed to reduce human interaction. Engelbert westkämper et al (2000) developed a robotic system for the automatic laying of tiles within certain tolerances on prefabricated modules. The pilot work consisted of a tile laying system that consists of tile positioning equipment, a centering and measuring system and transport unit; a tile supply system consisting of a store and a measuring unit; system for generating process parameters; and handing and positioning system having industrial robot and process control. (5)
Moreover, Neelamkavil,J (2009) have illustrated that single-task robots technology will progresses quickly through the development of human-robot cooperative (HRC) system, key technologies development such as motion generation, remote control ,operation control, and mobility, there will be more interaction between humans and robots in workplace, human and robot will assist each other and exchange forces on site.
Construction automation system consists of four fundamental components;
An on-site factory protected by an all-weather enclosure.
an automated jacking system
an automated material conveying system
a centralized information control system
These systems have followed manufacturing principle as well as using "just-in-time" principles for delivery of materials and bar coding for tracking and placing materials once delivered on-site. The numbers of single-task robots used depends upon the job. (6)
SMART (Shimizu Manufacturing system by Advanced Robotics Technology) has demonstrated a computer integrated construction (CIC) approach, which realized the objectives on; automated production off-site, with robotic assembly on site, handing heavy components and interact with one another. It has also utilized automatic planning and construction site management technology, with using a computerized controlled system to monitoring building process on-site. The system has fully integrated industrial production methods with construction, where the theory of "Just-in-time" (JIT) and "constancy" could be realized throughout the construction process. (7)
Economically, due to the high cost of developing such automation system has affect on the speed of putting robotic systems in to practice. The most development has been done by some leading construction practice supported by large numbers of research organization. For example, in Japan most of major construction companies has large amount of research budgets and in-house research department working closely with universities and other institutes. Without strong financial capability an automated construction site will be impossible to implement.
Software and IT integration
Automated construction processes are not only relying on software and IT technology, but also associated with other related technologies, such as data processing, and Virtual Reality technology. These technologies control of construction machines and improve the construction efficiency. But more importantly, software integration is crucial for implementing the concept of computer integrated construction (CIC), which will enable to integrate prefabrication design process, advanced planning and management methods through a software system to programming on site robots and simulate the construction process. Neelamkavil,J (2009) reported The EU Future Home projects, the projects have developed the AUTOMOD3 system- an automatic modular construction software environment, the system successfully integrated all stages of house-building construction process and automated construction methods in to a CAD program. Through using this program, each stage is simulated; from transfer 2D plan into 3D model to onsite robotic assembly each task can be carried out automatically.
The introduction of Computer aided design (CAD) has changed attitudes towards accuracy and efficiency within construction industry. The developments of newest software such as AutoDesk's Revit Architecture, SolidWorks are an upgrade of traditional CAD-based software, which enables designer, engineers, constrictors to analysis each stage of the building's lifecycle, from its concept stage to demolition and recycling, it will monitoring the whole building process. Through sharing information sources between key players within the company such as design data, financial data, legal data, and service layout, this will improve team communication and increase efficiency, constructability and ultimately predictability of all projects.
Construction industry facing challenges to responds to change technical, economic and social conditions, there is an increasing need of changing construction technique, communication and management strategy within the sector. This paper has explored the opportunities and challenges that advanced technology and modern manufacturing process offer to the construction sector, and illustrated few examples of how did the development of robotic technology is increasingly affecting the process of construction automation.
The need for improved automation and productivity of the construction industry is clear.
There are numbers of factors are needed to be stressed, and will affect on future implement;
Change of construction methods, result in organizational revolution. Design practice, client communication, product development, on-site assembly, use of construction robots, project management, and software development issues are highlighted and due for improvement.
The construction industry has shown a notable resistance to adopt new technologies, partly because the fragmentation of the industry makes it difficult for a single organization to invest in the system and to expecting a higher return from the investments. It is necessary to change attitudes in the construction companies, government authorities, and research and development sectors to working together to develop a system or product which could attract investments from other manufacturing industry.
The introduction of computer integrated construction and adoption of IT technology has changed the way construction industries operate, and specialized software and telecommunication tools will emerge.
Competition will drive construction industry to acting fast and take on changelings, which force construction companies to speed up automation and technology integration.
Fully automated construction systems are technologically sophisticated. A step-by-step strategy is needed enable to achieve automation;
From design to reality, the design of a building will take into consideration of each stages of construction process, such as prefabrication, assembly and transportation and recycle. Standard part will be used for variety of designs to increase production. System integration and software standardization to improve communication between architects, civil engineers, electrical engineers.
Pre-fabrication technology will be enhanced and expanded. New materials and building system will be developed to assist mass production. Building will be erected like a giant jigsaw. Computer Integrated Manufacturing (CIM) system to be introduced to redefine building as a customer oriented product, and can be purchased from dealer's catalogues.
The use of robots and automated machines is crucial to achieve automated construction. Construction robots will be easy to control and with artificial intelligent programming. Specific types of robots are designed for specialized task to maximize productivity. Real-time planning will commonly employed in tasks that require the robot to compete with undefined environments. Research work should also focus on various types of existing systems and machineries to identify opportunities for robotic alteration and also the development of multitasking robots with minimal human supervision.
Full automation is not economical right now but it will continue to improve work environment, reduce construction time waste, creating new jobs in construction industry.
Future success of construction industry is to obtain full automation; it is achievable, together with support of advanced technologies, appreciate system integration as well as a forward planning.