North American Special - Trenchless International

obotics
April 2009 - Trenchless International
The role of robotics in the
trenchless industry
by Paul Heenan
The official definition of a robot is “a machine or device that operates automatically or by remote
control,” yet this does not really define the information and functions that the robots in the
Trenchless Technology industry provide to engineers from local water authorities, municipalities and
other utility owners.
It can be argued that the first step
towards what we know today as ‘robots’
was the use of tube cameras to inspect
mainline sewers – CCTV inspection. This
system of cleaning and winching the camera
through the sewer was very labour
intensive and, due to these manpower
requirements, quite expensive. Despite
this, the information gathered was invaluable
in the asset management project.
The problem with the winch system was
that it required an entry and exit manhole;
to operate this system two access points
were required. For example, laterals that
connect from the property directly into
the main sewer lack the appropriate
access. The advent of the cable and
drain rods pushing system facilitated
these inspections. This was further developed
by Pearpoint Limited of the UK
(now part of SPX) when the conductors
that transferred the camera image to the
control screen were incorporated inside
a semi rigid rod, removing the need for
a separate cable and rod. Finally the
advance in technology of CCDs that
produce the image surpassed the use of
tube cameras and monochrome pictures
were replaced by colour.
The first camera-mounted robots –
crawlers/tractors – provided completely
new scope of possibilities. These robots
enabled increased inspection distances,
single entry point inspection and eventually
‘pan and tilt’, which allowed the
inspection of laterals from the main sewer
to the building. It was a major step for
the industry. Whether they were ‘shaft
driven’ or ‘chain driven’, the only limitation
became the loss of picture quality over
greater distances.
The risk of explosion created in sewers
or confined spaces produced the next
generation of robots. The advance in this
particular industry gave rise to explosion
proof systems, either by means of ‘flame
paths’ or ‘inert gas-filled,’ the robots can
now travel and inspect pipes that, 20
years ago, were uncharted territory.
All of this advancement had to be coordinated
and the results assessed using
a single system of examination.
In 1974, the Water Research Centre in
Swindon, UK provided such a method of
evaluation. The system of fault classification
and fault severity is used worldwide
in both normal sewer (OX20) and brick
sewer (OX21). The classification of grading,
1 (good) to 5 (collapsed or near
collapse), allows local water authority
engineers, municipalities or other utility
owners to set priorities in the next step
of sewer robotics – sewer rehabilitation.
So were CCTV inspection cameras the
original robots According to the definition,
cameras with remote functions such
as focus, iris and rotate functions, and
crawler/tractors obviously qualify. They
were and still are an extension of the
human eye.
Robots in sewer rehabilitation
If CCTV inspection is an extension of the
human eye, repair robots are an extension
of the human hand. These types of
robots are performing tasks remotely
and the benefits they provide, either
financially or solution wise, are incalculable.
The introduction of Trenchless
Technology gave local engineers a more
cost effective and cost efficient method
to maintain the sewer systems within their
control. Especially pertinent in today’s
financial situation, using trenchless solutions
makes the sewer infrastructure
rehabilitation budget stretch that little bit
further. The old idea of ‘dig it and fill it’ is
expensive and intrusive; in comparison
non-disruptive, remote repair by robot is
unobtrusive and inexpensive.
There are two main classes of rehabilitation
robot, those that grind or cut
and those that repair leaking joints or
laterals.
Grinding or cutting robots are the
teeth of the sewer rehabilitation industry,
removing intruding laterals or re-opening
the laterals of relined pipes can be done
with ease. The fundamental question that
arises is how the grinding/cutting can be
achieved quickly and cost effectively.
There are two main methods:
1. Air driven systems: air driven motors
that are used in the grinding produce
a good result in some materials, but
not in all. The torque produced at
the point of grinding/cutting can be
considerably less than the alternative,
hydraulic driven. The other problem,
as most people are aware, is reliability
and maintenance. The amount
of debris and vibrations created during
the process can cause slow and
expensive repairs.
2. Hydraulic driven systems: the use of
hydraulic methods has shown that the
vibrations and debris have no effect on
the reliability of the system. The torque
produced at the point of grinding/cutting
easily and quickly deals with any
material. This makes the system more
cost effective and efficient. Although
the amount of investment required in
owning such a system can be higher
than air driven systems, the difference
is soon recovered with the increase of
productivity.
KATE-PMO AG of Freienbach,
Switzerland, a leading manufacturer of
hydraulic driven grinding/cutting robots
for over 20 years, pioneered the use of
this type of robot system and still has
originally manufactured systems working
in Germany today.
Lateral repairs
In 2004, an independent German
organisation IKT (Institut für Unteridische
Infrastruktur), together with 26 sewage
network operators from different cities,
assessed the different methods available
for the repair of sewer pipe lateral connections.
In order to assess the products
capability of sealing internally and externally,
the repairs ranged from standard
damage to strong damage. A system of
measurement was introduced:
• Very good – 1.0 to 1.5
• Deficient – 5.6 to 6.
Seven robotic systems were tested and
comparatively evaluated. In these tests it
was shown that the system of repair from
KATE-PMO AG was the highest rated
product. Using the lateral shield, more
than one repair can be carried out in the
sewer length at any one time. The shield
can be adjusted to suit the angle of entry
into the sewer making a perfect mould for
the resin to bond to the pipe material.
Alternative robots in the sewer
The use of sewers to deploy cables
is not a new idea; it was first pioneered
by the French in Paris at the turn of the
1900s. Robots have been developed by
companies, including KATE-PMO AG, to
deploy fibre optic cables in sewers with
diameters from 200 mm up to and including
700 mm. What is special about this
system is the software that creates a
map of the sewer line. Each joint, lateral
or defect is measured and recorded.
The position of the tubes is set by the
clamps installed in the sewer length in
order to avoid interfering with laterals
and the primary use of transportation of
waste material. More than 400,000 metres
have been installed to date with minimum
excavation, making it an environmentally
friendly solution for telecommunication
companies, disaster recovery situations
and local authorities.
The Future
The future for robotics in sewers is
vast, and the ever increasing market in
Trenchless Technology will no doubt
provide new advances in the design,
manufacture and materials. Reliability
and quality must be maintained in order
to consolidate the trenchless industry in
today’s market place.
Paul Heenan is the International
Sales and Marketing Manager
for KA-TE.
Robotics
April 2009 - Trenchless International
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