21-01-2013, 01:16 PM
Robotic Platform for Monitoring Underground Cable Systems
1Robotic Platform.pdf (Size: 366.95 KB / Downloads: 108)
Abstract
Accurate, real-time information about the aging
status of the power distribution cable network can save the
power industry millions of dollars lost due to line failures and
premature replacement of cables. Hence, a novel, semiautonomous
robotic sensor platform has been developed for
monitoring underground, power distribution cable systems. A
segmented, legged modular configuration allows the robot to
traverse cables with a diameter of four to eight centimeters and
negotiate obstacles along its path. The design of platform
consists of a multi-processor control board, a 900 MHz wireless
communication module, and infrared, dielectrometry, and
acoustic sensors. The robot is capable of fully autonomous
operation or human tele-operation via a LAN or Internet
connection. A prototype platform has been developed and tested
with a 14kV distribution cable. Currently, sensor integration is
underway.
INTRODUCTION
The nationwide power distribution network contains
millions of miles of cable, all in various states of aging.
Currently, cables are replaced either reactively (when a fault
occurs) or periodically. Reactive replacement often results in
loss of service, leading to lost customer revenue, whereas
periodic replacement is costly because lines that could have
several more years of reliable operation are replaced
prematurely. A case study showed that up to 2/3 of the cable
system that is scheduled for replacement could be kept in
service with predictive diagnostics [1]. Real-time knowledge
of the aging status of these cables can save the power industry
millions of dollars in lost revenue.
ROBOT PLATFORM
Specific challenges associated with this application include
space confinement, size and weight restrictions, wireless
communication requirements, and adverse environmental
conditions.
System Overview
A unique segmented configuration allows the robot to
traverse cables with a diameter of four to eight centimeters
and negotiate obstacles along its path. The design of platform
consists of a custom multi-processor control board, a 900
MHz wireless communication module and multiple sensor
arrays. Fig. 1 and Fig. 2 show the conceptual design and a
picture of the mobile platform.
Internet remote control
A complementary PC application was developed in parallel
with the platform to control the robot and analyze gathered
data. The software was designed with a modular architecture,
so that as the project grows, the user can simply replace
functional modules rather than integrate new code into a
monolithic program. The resulting architecture consists of a
suite of modules that interact through software sockets as
shown in Fig. 5.
Each module communicates with the main control program
via bi-directional asynchronous software socket connections.
The main control program issues high-level commands and
routes data between the functional modules. For instance, the
main control module can issue high level commands to the
communication module, which in turn relays the signal to the
robot. The data processing and data visualization modules
have yet to be implemented.
Infrared sensors
Thermal analysis plays an important role in the evaluation
of insulation status. Polymers commonly used as electrical
insulation are thermally sensitive due to the limited strength of
the covalent bonds that make up their structures. The lifetime
of electrical insulation is reduced when it is subjected to
continuous overheating. One experiment showed that reducing
the accelerating aging test temperature from 90