Content uploaded by Ehsan Asadi
Author content
All content in this area was uploaded by Ehsan Asadi on Oct 07, 2017
Content may be subject to copyright.
Innovations in Infrastructure Service
Robots
I-Ming Chen, Ehsan Asadi, Jiancheng Nie, Rui-Jun Yan,
Wei Chuan Law, Erdal Kayacan, Song Huat Yeo,
Kin Huat Low, Gerald Seet and Robert Tiong
Abstract Infrastructure service robotics is a discipline studying robotic systems
and methodology for buildings and civil infrastructure construction, inspection, and
maintenance. The target could be buildings, estates, parks, bridges, power plants,
power transmission lines, underground tunnels, sewage pipes, port facilities, etc. In
this article, several new infrastructure service robots projects for construction ser-
vices and deep tunnel inspection carried out in Singapore will be introduced. With
new actuators, low cost sensors, and open source robotics software, infrastructure
robots represent a new breed of intelligent systems that help the society to over-
come manpower shortage and ageing workforce. These projects are examples of
user-led and user-inspired robotics R&D effort led by government agencies, uni-
versities, and industrial alliance of local and overseas robotics and construction
machinery manufacturers, start-up companies, and system integrators. The ultimate
goal is to strengthen the robotics R&D capability in Singapore and to foster a
robotics industry and the ecosystem that transform Singapore into a Smart Nation.
Keywords Professional service robot ⋅Construction robot ⋅Large-diameter
tunnel inspection robot
I.-M. Chen (✉)⋅E. Asadi ⋅J. Nie ⋅R.-J. Yan ⋅W.C. Law ⋅E. Kayacan ⋅S.H. Yeo ⋅
K.H. Low ⋅G. Seet
School of Mechanical and Aerospace Engineering, Nanyang
Technological University, Siangapore, Singapore
e-mail: michen@ntu.edu.sg
R. Tiong
School of Civil and Environment Engineering, Nanyang
Technological University, Singapore, Singapore
© CISM International Centre for Mechanical Sciences 2016
V. Parenti-Castelli and W. Schiehlen (eds.), ROMANSY 21 - Robot Design,
Dynamics and Control, CISM International Centre for Mechanical Sciences 569,
DOI 10.1007/978-3-319-33714-2_1
3
1 Introduction
Infrastructure service robotics is a discipline studying robotic systems and
methodology for buildings and civil infrastructure construction, inspection, and
maintenance. According to the classification by International Federation of
Robotics (IFR), such service robots include professional cleaning systems for
floors, windows, walls, tank, hulls and pipes, inspection and maintenance systems
for facilities, plants, tanks, tubes, and pipes, and construction and demolition sys-
tems for nuclear plants, building, civil/heavy structures, and road constructions.
Developing robotic technology for infrastructure services has the following
significance:
(1) Economics and sustainability—Robotic technology would be able to reduce
the reliance on unskilled workers and also skilled workers operating on
sophisticate construction machinery.
(2) Productivity—Robotic technology will streamline and further optimize cur-
rent construction process for shorter project period, and also assure quality
consistency of the construction project.
(3) Safety and health—Robotic technology will reduce the human exposure to
hazardous and inaccessible environment during construction.
Due to the recent advancement in robotic technology and cost down on key
robotic components, such as low cost 3D imaging sensors, high precision 3D laser
scanners, high density lightweight actuators, open source robotics software, AI and
cloud computing, standardized plug-and-play components, and robust wireless
communication and control, developing innovative robotic systems to service
public infrastructure and private estates become affordable. However, there are still
a number of technical challenges to overcome before these professional service
robotic systems making massive inroad into real world services. These challenges
include:
•Complete understanding of existing human workflow and processes and also the
limitations in the application domain
•Performance evaluation, validation, and optimization of sub-systems and the
overall robotic system for field operations
•Designing robustness robotic manipulation, mobility and perception modules
for field operations
•Developing machine learning and intelligence for robotic systems that can adapt
to environment and task variations in the fields.
•Designing suitable level of human-robot interaction and machine autonomy for
effective operations
In this paper, we introduce three new infrastructure service robot projects for
construction services and deep tunnel inspection carried out in Singapore. The basic
design consideration and technology developed and integrated into the system will
be presented. Preliminary results on these robots in lab trials will be described.
4 I.-M. Chen et al.
Finally, the paper will be concluded with some thoughts on further development
and commercialization of these professional service robots.
2 Mobile High-Rise Spray Painting Robot
2.1 Motivation
Despite the rapid technology evolution, construction services are mostly
labors-dependent and performed with conventional techniques and occasionally in
dangerous situations. Beside the low efficiency in this sector, the needs for building,
construction and maintenance are growing rapidly all around the world while the
construction industry is facing a future shortage of skilled workers and wage
increases. It is evident that inefficient management of resources and use of unskilled
workers can result in a considerable decline in construction quality and produc-
tivity. Hence, there is a high demand for introducing novel robotic technologies that
can be applied to boost productivity by focusing on quality and time saving, as well
as to enhance safety and to reduce cost compared to the traditional method.
An overview of the relevant state of art on construction robots indicates a lack of
advanced and multi-purposes robots for construction painting; particularly for
interior finishing where only very few robots were designed and developed. The
feasibility analysis and economic impact of robotizing interior finishing services for
productivity improvement on the construction sites were initially studied by
Rosenfeld et al. (1993), and Warszawski and Rosenfeld (1994,1997). Later,
Kahane and Rosenfeld (2004) developed a method for evaluating the effects of
human-and-robot integration on automating a construction task and examined the
method using an interesting multi-purpose robot, named TAMIR, for block laying
and wall painting. The painting system consists of a commercial 6-DOF robot arm
mounted on a computer controlled 3-DOF mobile platform. The robot was designed
for research and development purposes, and it had an average reach access. Aris
et al. (2005) mainly investigated the problem of automating upright spray painting
for only ceiling finishing by designing a 3-DOF robot. The ceiling painter is derived
horizontally by making use of a single-phase induction motor and a chain-sprocket
mechanism and moved vertically via a zigzag ladder structure. The painting
workspace of the robot is significantly small relative to the platform size. Another
study (Naticchia et al. 2007) introduced a scaled down interior painting set up for
laboratory use that consists of a 6-DOF manipulator to be mounted on a 2-DOF
Hexapod for horizontal movement. The research also studied reproducing colored
artworks by developing a multi-colored spraying tool. A roller-based interior wall
painting robot was proposed by Sorour et al. (2011), which includes a horizontally
moving platform (3-DOF), and a painting arm (2-DOF) with a roller brush, attached
to end-effector, which solely scans the walls vertically up to 2.7 m. As a very
low-cost robot, Keerthanaa et al. (2013) designed an airbrush spraying system for
Innovations in Infrastructure Service Robots 5
interior finishing of simple and small spaces. The robot was equipped with a
four-wheel platform, conveyor shafts, and chain-sprocket that allow transferring
spraying system vertically up to limited height.
To the best of our knowledge, none of the previously reported paint robots is
capable of delivering all desirable functionalities for interior finishing of the ceiling
and walls of high-rise warehouses within a stand-alone automated system. All the
existing indoor paint robots have low or average reach access and do not suit for
painting high rise ceilings and corners. Besides, most of the paint robots are merely
able to paint walls or to paint ceiling due to the insufficient mobility or autonomy of
robots. High ceiling painting is inevitable and common in building construction,
especially in industrial workshops. Traditional high ceiling painting is manually
done by means of ladders or hydraulic lifts and often results in unreliable painting
quality. It is hard to obtain consistent quality because of the unstable working
position and movement of the worker thus yielding a big difference in productivity
in accordance with the level of worker’s skill and experience. Moreover, the
high-place operation will create lethal dangers to painting workers. This project
aims to develop an advanced paint robot that enables automating the execution of
interior painting of high-rise ceilings and walls. A modular system is considered in
this work, and the robot is designed with five primary subsystems: a 3-DOF mobile
robot, a 1-DOF long reach mechanism, a 6-DOF commercial robot arm, a spraying
system and a control and safety system. The proposed system configuration enables
free access to a large workspace for painting ceilings and walls up to 10 m height
and can improve the productivity due to the precise robot movement and even paint
distribution throughout the whole painting patches.
2.2 Overall System
This project aims to develop a stand-alone robot with a higher degree of mobility
compared to other existing indoor paint robots and with particular functionalities for
automating the entire process of interior finishing of high-rise spaces. Unlike the
other existing interior paint robots, the proposed robot includes a novel long reach
mechanism that enables paint delivery to high-rise walls and ceilings. Modular
design is considered in this work to reduce the design complexity at conceptual and
technical levels, and to accelerate the manufacturing cycle as well as to increase the
flexibility of system integration and upgrade. By considering a modular system, the
robot is designed with five primary subsystems: a 3-DOF mobile robot, a long
1-DOF reach mechanism, a 6-DOF commercial robot arm, a spraying system and a
computer-controlled system. Besides, the robot consists of several subsidiary
modules such as hydraulic outrigger stabilizers, the cable-hose suspension system
and diverse types of covers to protect the equipment and sensors against paint
pollution.
The proposed system configuration enables free access to a large workspace for
painting ceilings and walls up to 10 m height and sufficient maneuverability to paint
6 I.-M. Chen et al.
corners and non-planar surfaces. Using the proposed paint robot can improve the
productivity due to the precise robot movement and even paint distribution
throughout the whole spray pattern that ensures all painting patches receives a
certain amount of paint precisely and consistently.
2.3 Robotic System Realization
The mobile robot, the first module, is designed to carry heavy payloads with
zero-turn maneuverability by utilizing a combination of two driving wheels and six
passive ones. The second module, long reach mechanism, comprises a dual mast
telescopic lift mechanism that is derived up to certain heights via deploying
hydraulic cylinders in conjugation with a series of cables, and it is centrally
embedded in the mobile platform. The third module is a six degree-of-freedom
robot arm, outfitted with a spray-painting gun and time-of-flight camera on its
end-effector, to be located on a right spot on top of the long reach mechanism. The
commercial airless spraying system is selected for the fourth module, together with
an electrically actuated spray gun that allows high-quality interior finishing without
the need for the air compressor. All spraying subsystems are mounted on the mobile
robot that enables the free navigation of the robot within the construction site. To
accomplish the painting task freely in large spaces, having a high level of autonomy
and safety is vital. As the fifth module, the mobile robot will be endowed with
several levels of autonomous capabilities for traveling through the construction site,
for levelling the mobile robot attitude, for adjusting the altitude of lift mechanism,
for planning the manipulator motion, for executing the spray painting task and for
safety management.
A preliminary design of the robot is depicted in Fig. 1, in which the upper part
covers of the robot and detailed design of subsidiary modules are not shown.
Figure 2demonstrates the manipulator arm currently set up in the lab to conduct
Fig. 1 Preliminary design of
high rise spray painting robot:
1—mobile robot (3-DOF),
2—spray painting system,
3—dual mast telescopic
mechanism (1-DOF),
4—control box,
5—manipulator (6-DOF)
Innovations in Infrastructure Service Robots 7
preliminary experiments for developing motion planning and vision processing
algorithm. The robot arm is effectively outfitted for a real paint operation by con-
sidering protective covers for both the arm and the camera coupled to the
end-effector as an eye-in-hand system.
3 Post-construction Quality Assessment Robot
3.1 Motivation
Post construction quality assessment of buildings is an indispensable procedure in
construction industry that is currently executed by manual inspectors. In a standard
daily operation, a large number of inspectors are needed to finish the wholly manual
assessment in the traditional way. Such a manual assessment procedure may import
several errors into inspection because of executing the operation in incorrect way or
the use of inaccurate inspection tools. What is more, the manual inspector may get
tired after some time and the inspection accuracy may decrease over time. In most
of the time, manual inspection has to be done during the daytime. Considering this
time consuming, tiresome and unexciting procedure, an automated post construc-
tion quality assessment robot system is proposed in Fig. 3. The proposed robot
system consists of a mobile robot, a 2D laser scanner, a thermal camera with a
heater and an inclinometer (Axon Robot is from CtrlWorks Pte Ltd). This robot
system can assess five different types of defects on the floors and walls, such as
evenness, alignment, inclination, cracks and hollowness.
Fig. 2 Manipulator setup outfitted with camera, spray gun and protective covers
8 I.-M. Chen et al.
3.2 Quality Assessment Methodology
In traditional assessment, cracks of grounds, walls and ceiling are visually
inspected. Evenness of ground and walls is inspected by using a 1.2 m spirit level,
and alignment of two walls is inspected by using a set square in Fig. 4. In the
assessment process of alignment, one edge of the setsquare tightly contacts with
Fig. 3 Automated
construction quality
assessment system
Fig. 4 Manual assessment tools and autonomous assessment sensors
Innovations in Infrastructure Service Robots 9
one wall (Ani et al. 2014), and the distance between the other one edge and the
other wall is calculated. Beyond doubt, measurement error is imported into the
operation during the assessment process, because it is a challenging task for the
inspectors to accurately keep the setsquare horizontal. To assess the hollowness, the
inspector needs to cover the whole ground with the end-effector of a CONQUAS
rod. Then, the ground with hollowness is inspected by distinguishing the scuff-
ing noise of the ground and the CONQUAS rod.
Considering this time consuming, tiresome and unexciting procedure of manual
assessment, our proposed robotic system can accurately assess all these defects in
real time. A Hokuyo UTM-03LX 2D laser scanner shown in Fig. 4is used to
localize the mobile robot and construct an environment map that can be used to
store the accurate locations of defects. A Sick LMS 500 2D laser scanner is used to
assess the evenness of ground and walls, and the alignment of two walls, which has
a maximum measurement distance of 80 m, a measurement accuracy of 6 mm and
a measurement range of 190°. The evenness is assessed by calculating the average
deviation between raw sensor data and its extracted line segment, which have been
mostly used to build a 2D environment map and localize a mobile robot (Yan et al.
2014,2015a,2015b). The alignment of walls is assessed by calculating the angle of
two extracted planes. The inclination of ground is assessed by directly obtaining
inclination angle in X- and Y-axis from a POSITAL inclinometer. To assess cracks
and hollowness, thermal camera and a heater are used to obtain thermal images and
RGB images. Then, these images are recognized by using support vector machine
(SVM) method.
3.3 Experimental Results
Assessment results of evenness, crack and hollowness are shown in Figs. 5and 6.
In Fig. 5, the laser scanner is horizontally put on the ground of a constructed
testbed. In the construction of this testbed, wall 1 is an even wall and wall 2 is an
uneven wall. It can be seen from the comparison result of the average deviation for
two walls that the average deviation of wall 1 is larger than that of wall 2. In
Fig. 6a, the assessment result of a tile with cracks is shown by comparing the raw
images and the processed images with SVM. In Fig. 6b, even though the color
difference in the raw thermal image is not very clear, the process images can show
the hollowness result well. These promising results show that the proposed auto-
mated construction quality assessment robot system works well in the identification
of different types of defects.
10 I.-M. Chen et al.
Fig. 5 Assessment result of evenness
Fig. 6 Assessment result of
crack and Hollowness. aAn
example of crack assessment
bAn example of hollowness
assessment
Innovations in Infrastructure Service Robots 11
4 Deep Tunnel Sewerage System Inspection Robot
4.1 Motivation
The Deep Tunnel Sewerage System (DTSS) is a public wastewater utility based in
Singapore, a solution to meet Singapore’s long term needs for used water collec-
tion, treatment, reclamation and disposal. It has diameter of 6 m, and it is located
20–50 m underground. In order to prolong the service life of the sewers, the
maintenance task such as inspecting the structural integrity of the tunnel is nec-
essary. Human cannot easily access to DTSS because of high water flow, the
presence of contagions or bio-hazardous materials, explosive gases and oxygen
deprivation (Walter et al. 2012), as well as the absence of light in DTSS. Also, the
tunnel is partially filled with water and muddy ground that is not easy for human to
walk across. Significant study on pipeline and tunnel robot has been done due to its
ability to access underground spaces and to achieve easier and better inspection in
tunnels. However, most of the existing robots are designed for small or medium
pipelines and tunnels (Law et al. 2015). There is a need to develop a tunnel robot to
perform the maintenance of large-diameter tunnel.
4.2 Overall System
A generic locomotion mechanism for DTSS robot is designed that could cope with
various tunnel conditions from dry, muddy, and partially filled water. On the other
hand, a hoisting system will be configured for the launching, deploying and
retrieving of the inspection robot. The setup of the inspection system consists of a
number of subsystems, namely the auxiliary system and ground control station, the
hoisting and winch system, and the robotic platform as shown in Fig. 7.
On the surface, the auxiliary system provides electrical power to the winch and
the robotic platform as well as hydraulic power to actuate the A-frame. The control
station houses the control units for the robotic platform and monitors displaying
images from cameras and measurements from sensors.
The hoisting and winch system comprises an A-frame, a winch module and an
umbilical cable. The A-frame is for lowering and lifting the robot along the access
shaft without the needs of any other heavy-duty hoisting devices. The winch is
mounted on the platform of the A-frame for easy transport and operation. An
external 3-Phase AC power generator will supply the power to the winch module
and provides power supply for the tethered robotic platform. The electrical power is
transmitted through the multi-core umbilical cable carrying a Kevlar core, data optic
fiber and multi-core copper wires.
The robotic platform has its own actuation and houses various sensors needed
for the inspection of the sewer tunnel. In particular, it will have lightings to illu-
minate the tunnel and cameras to capture the tunnel images. A laser profiler and a
12 I.-M. Chen et al.
sonar profiler are utilized to scan the tunnel above and below the water surface
respectively. A ballast control is used to vary weight of the robot to maintain the
maneuverability and stability of the robot in accordance to the internal condition of
the sewer.
4.3 System Designs
In Fig. 8, the semi-circular frame is designed for the mounting of 3 HD cameras and
4 LED spotlights, forming an inspection array radially at equal angle apart. It will
be mounted on the chassis of the robotic platform facing towards the inner cir-
cumference of the sewer, covering the surface of the sewers above the water level.
The base plate is the main support structure of the robotic platform. All the
mechanical parts will be mounted on the base plate, for instance, the front and rear
camera, the locomotion mechanism, ballast, etc. Two waterproof enclosures, fixed
on the base plate, are used to house the electrical components such as controller and
drivers. The front facing camera is at a high position in the sewers, allowing an
unblocked field of view of the sewer for navigation. Moreover, the robotic platform
has low center of gravity and has large base to increase the robot stability.
Figure 8also shows the situation when the robotic platform is deployed into the
tunnel through the vertical shaft. The locomotion mechanism in this design can be
tilted to certain angle that is perpendicular to the sewer surface before the robot
lands onto the sewer to avoid the possible presence of soft debris along the bottom
Fig. 7 Setup of inspection system
Innovations in Infrastructure Service Robots 13
of the tunnel and to acquire better traction force over the sewer surface. This is
achieved via a slider-crank mechanism that is used to transform translational motion
into rotational motion.
5 Conclusions and Discussion
The infrastructure service robot projects introduced in this paper represent a new
breed of service robots that are developed based on end-user input and more
cost-effective, more compact, and more versatile than before. With advancement in
sensors, actuators, and artificial intelligence, such robots could conduct service
tasks autonomously with minimal human supervision. It is also possible to use such
service robots with human collaboratively. The robot can perform simple, mundane,
and large-scale tasks, whereas the human worker can conduct complex and
sophisticate task that could be too expensive for robot to do. In such way, there
could be “robot shift”and “human shift”co-existing in the work place. Such
practices could create a paradigm shift in productivity for the future society with
lots of professional service robots. Also there could be innovative workflow
re-design due to such autonomous service robots along side with cloud services and
big data analytics. The integration of infrastructure service robots, big data collected
through the robots, and the value-add to the end users, as a complete service could
be the future form of infrastructure service robotics companies.
Acknowledgments The research projects are supported by National Research Foundation of
Singapore under TDIR2015-01-02, TDIR2015-01-03, and TDIR2015-01-04. Team members,
Chen Qiu, Lijing Soh, Lili Liu, Varun Maruvanchery, Chin Leong Low, Burhan, and company
co-developers, Aitech and CtrlWorkds are acknowledged. Lead public agencies, Jurong Town
Corporation, Building Construction Authority, and Public Utility Board of Singapore are
acknowledged.
Fig. 8 Robotic platform for DTSS
14 I.-M. Chen et al.
References
Ani, A., Tawil, N., Johar, S., Razak, M., & Yahaya, H. (2014). Building condition assessment for
new houses: a case study in terrace houses. Journal Teknologi, 70(1), 43–50.
Aris, I., Parvez Iqbal, A. K., Ramli A. R., & Shamsuddin, S. (2005). Design and development of a
programmable painting robot for houses buildings. Journal of Teknologi, Universiti Teknologi
Malaysia, 42(A): 27–48.
Kahane, B., & Rosenfeld, Y. (2004). Balancing human-and-robot integration in building tasks.
Computer-Aided Civil and Infrastructure Engineering, 19, 393–410.
Keerthanaa, P., Jeevitha, K., Navina, V., & Indira, G. (2013). Automatic wall painting robot.
International Journal of Innovative Research in Science, Engineering and Technology, 2(7),
3009–3023.
Law, W. C., Chen I. M., Yeo, S. H., Seet, G. L., & Low, K. H. (2015). A study of in-pipe robots
for maintenance of large-diameter sewerage tunnel. In Proceedings of 14th IFToMM World
Congress in Mechanism and Machine Science Conference, Taipei, Taiwan, 25–30 Oct 2015.
Naticchia, B., Giretti, A., & Carbonari, A. (2007). Set up of an automated multi-color system for
interior wall painting. International Journal of Advanced Robotic Systems, 4, 407–416.
Rosenfeld, Y., Warszawski, A., & Zajicek, U. (1993). Full-scale building with interior finishing
robot. International Journal of Automation in Construction, 2(4), 229–240.
Sorour, M. T., Abdellatif, M. A., Ramadan, A. A., & Abo-Ismail, A. A. (2011). Development of
roller-based interior wall painting robot. World Academy of Science, Engineering and
Technology, International Journal of Mechanical, Aerospace, Industrial, Mechatronic and
manufacturing Engineering, 5(11), 1785–1792.
Walter, C., Saenz, J., Elkmann, N., Althoff, H., Kutzner, S., & Stuerze, T. (2012). Design
considerations of robotic system for cleaning and inspection of large-diameter sewers. Journal
of Field Robotics, 29(1), 186–214.
Warszawski, A., & Rosenfeld, Y. (1994). Robot for interior finishing works in building—
Feasibility analysis. ASCE Journal of Construction Engineering and Management, 120(1),
132–151.
Warszawski, A., & Rosenfeld, Y. (1997). Economic analysis of robots employment in building.
Proceedings of the 14th International Symposium on Automation and Robotics in Construction
(ISARC) (pp. 177–184). Pennsylvania, USA: Pittsburgh.
Yan, R. J., Wu, J., Yuan, Q., Yuan, C., Luo, L.-P., Shin, K.-S., et al. (2014). Natural corners-based
SLAM with partial compatibility algorithm. Proceedings of IMechE, Part I: Journal of systems
and Control Engineering, 228(8), 591–611.
Yan, R. J., Wu, J., Shao, M.-L., Shin, K.-S., Lee, J.-Y., & Han, C.-S. (2015a). Mutually converted
arc-line segment-based SLAM with summing parameters. Procedings of IMechE, Part C:
Journal of Mechanical Engineering Science, 229(11), 2094–2114.
Yan, R. J., Wu, J., Lee, Y., & Han, C.-S. (2015b). Representation of 3d environment map using
b-spline surface with two mutually-perpendicular LRFs. Mathematical Problem in Engineer-
ing, 2015(690310), 1–14.
Innovations in Infrastructure Service Robots 15
Author Biography
I-Ming Chen received his Ph.D. in Mechanical Engineering
from California Institute of Technology, Pasadena, USA in 1994.
He is an internationally renowned robotics researcher and has
been with the School of Mechanical and Aerospace Engineering
of Nanyang Technological University (NTU) in Singapore since
1995. Currently he is the Director of Robotics Research Centre
in NTU.
His research interests are in collaborative robots, infrastructure
robots, wearable sensors, human-robot interaction, reconfigurable
automation, and parallel kinematics machines (PKM).
He is now serving on the editorial board of Mechanism and
Machine Theory, Robotica (Cambridge Univ Press), and Frontiers
of Mechanical Engineering (Springer-Verlag) as well as senior
editor of IEEE Transactions on Robotics. He was Technical Editor
of IEEE/ASME Transactions on Mechatronics from 2003 to 2009.
Professor Chen is a Fellow of IEEE and Fellow of ASME, General Chairman of 2017 IEEE
International Conference on Robotics and Automation (ICRA 2017) in Singapore.
16 I.-M. Chen et al.