Multi-access control of distributed mobile robotic systems based on networking technologies.
Andreev, Victor Pavlovich ; Pryanichnikov, Valentin E. ; Prysev, Evgeny Aleksandrovich 等
1. INTRODUCTION
The main direction of studies at the International Laboratory
"Sensorika" is the development and creation of different
technological robots and equipment of robotic complexes with sensor
systems of different designation. First of all, it is application of
ultrasonic sensors and computer vision systems. We have big experience
of installation of such sensors onto road-building, hydroficated boring
robots, underwater devices and robotic complexes used by the Russian
Emergency Situations Ministry. The objective of these studies is the
search of solutions for problems of automobile driving, marker
recognition, identification of passages, etc. This paper is devoted to
the new direction of the development of robotic complexes--multi-access
control of mobile robots, based on the networking technologies.
2. COMPUTER VISION FOR SUPERVISOR CONTROL OF MOBILE ROBOTS
At the first stage we consider this problem in a limited version,
namely, as the application of networking technologies for providing the
group of robots with the controllable computer vision system (Andreev et
al., 2009). Usually a computer vision system is the set of technical
tools and methods for obtaining, processing, and transmitting images
(and data loop), including automatic image analysis and decision making
(for example, measurement of geometric and other parameters of objects
of the image) and production of control signal supplied to executive
mechanisms (for example, in sorting). In a narrow interpretation a
computer vision system is the system in which final image analysis and
decision making is performed by the man-operator. This is the case most
often applied in robotic complexes used by the Russian Emergency
Situations Ministry. Several video sensors (for example, video cameras)
are installed on robotic complexes with supervisor control and this set
of video signals should be transmitted via wireless systems to the
monitor for analysis of obtained images by the operator; the operator,
in turn, controls the executive mechanisms of this complex via the radio
channel.
The main functions of computer vision systems assume the existence
of the following components: 1. Video signal sensors (one or several
video cameras) installed on board the mobile robot; there can be several
such robots.
2. System for collection and primary processing of video data
(transformation to the digital form, compression, and formation of
Ethernet signal) also installed on board the mobile robot (usually video
server).
3. Element of radio channel formation (Wi-Fi
reception-transmission); this is the access point with external antenna
installed on board each mobile robot.
4. Control panel on which Wi-Fi reception-transmission
radio-channel-forming element is installed; for example, it is the
access point with external antenna, computer, and monitor (or several
monitors) for depicting images from video cameras.
5. Systems of autonomous power supply of electronic blocks.
6. In a number of cases computer is installed on board the mobile
robot.
"Satellite" video cameras can be used to simplify the
work of robotic complex operator; these cameras are placed in direct
neighborhood of the zone in which the mobile robot operates and make it
possible for the operator to watch executive mechanisms of the mobile
robot; these devices should be autonomous and directly connected with
the control panel via Wi-Fi. These satellites can be situated on a
simplified mobile chassis (robot-observer).
The main specific feature of our approach to construction of
computer vision systems is the transformation of analog video signal
from video cameras into the digital form which allows application of all
available technologies of signal digital processing and transmission.
The most interesting is the Ethernet technology which makes it possible
to create computer network including several nodes, a PC on board each
mobile robot, a PC at the control panel, Wi-Fi access point, video
servers, and so on.
This technology was used at out laboratory to develop computer
vision systems installed at the robotic complexes BROKK-110D (Fig. 1a) u
BROKK-330 (Fig. 1b).
[FIGURE 1 OMITTED]
Three robots "AMUR" for education, training were
implemented in this technology (Fig. 1c) and supplied to the Vladivostok
Technical University and Academy of Sciences (Pryanichnikov et al.,
2009). At the present time the rover-robot is in the phase of the
producing on the base of the chassis for Mars exploration (Fig. 1d). It
will have a wide set of sensors and intellectual control.
Promising developments of the laboratory are much wider.
3. MULTI-ACCESS CONTROL
Uniting into one computer network elements of computer vision
system of a mobile robot is just the first step. It is interesting to
unite computer vision systems of several mobile robots into one computer
network which makes it possible to perform salvage operations by means
of several robots equipped by different tools. In this case a two-level
robotic control system should be constructed. The first level includes
operators of robotic complexes. The second level includes the commander
who coordinates operator's work. For this purpose the commander
should see the whole scene and obtain video information simultaneously
from all robotic complexes participating in the operation. Ethernet
technologies make it possible to construct such control system. For this
purpose it is sufficient to include commander's PC into the
computer network and equip the whole network with corresponding
software.
The software of the learning and training class of electronic
trainers developed at the International Laboratory "Sensorika"
for Engineering Technical and Training Robotics Center can be used as
the basis for creation of such software. This class (which is still in
use) was designated for high quality preparation and regular training of
operators of ground robotic tools and remote controlled systems used for
elimination of the consequences of emergencies connected with radiation
and other factors that forbid the presence of personnel in the zone of
operation. This class included 8 P[C.sub.s] and one server united in one
computer network. This made 7 workplaces for operator's training,
one workplace for the instructor, and one workplace combined with the
server for the observer. The developed software provided simultaneous
learning and training of 7 operators of mobile robots with one
instructor. Such network and software structure can be transferred (with
certain revision and update) to the acting complex of several mobile
robots, each controlled by individual operator. In this case the
instructor serves as the commander.
4. REMOTE CONTROL
Another specific feature of Ethernet technologies is that the
commander's PC can be situated practically any distance from the
zone of salvage operations (Andreev et al., 2009). It is sufficient to
have high speed Internet channel with assigned IP address in the zone of
salvage operations and the place of the command post. Such channel makes
it possible to unite into one network the commander's PC (or the
whole network of the command post) and the network connecting electronic
components of robotic complexes participating in the operation. For
protection of such Internet channel from unauthorized access it is
necessary to use special router capable of creating VPN channel at both
ends. Creation of such systems is the promising direction of development
in the interests of the Russian Emergency Situations Ministry.
Experts of International Laboratory "Sensorika" united
mobile robots situated in the buildings of the Institute of New
Educational Technologies and Informatization of the Russian State
University for the Humanities, Keldysh Institute of Applied Mathematics of the Russian Academy of Sciences, and in Vladivostok, into one network
via VPN channels (Andreev et al., 2009). Corresponding software was
developed which provided remote monitoring of the scene and control of
these robots according to the created technology of overcoming
inhomogeneities and delays in communication channels. Such elements of
the system as satellite video cameras become especially important. In
this case the operator can observe the scene via the robot eyes (video
cameras) and watch the robot movements and execution of commands
initiated by the distant operator from the outside.
5. CONCLUSION
It should be noted that the activity in the framework of the
concept of construction of computer vision systems with supervisor
control proved to be the correct choice. Technically, further activities
will be aimed at unification of elemental base of electronic components
of mobile robots in order to provide easy transfer of all developments
of the laboratory concerning training robots to robots used by the
Russian Emergency Situations Ministry and other structures. Certain
emphasis should be made on providing the sensor system of robots with
the set of different sensors, including ultrasonic and IR vision.
Seemingly, IR vision systems comprise a separate task different
from the problems of providing robotic complexes by sensor information.
However, including IR vision into robotic system complexes may provide
essential effect in application of robots, for example, for perimeter
protection. At present there exist a number of problems concerning their
application, first of all, the problem of parameter spread of
multi-element radiation receivers. The influence of this parameter
spread on the video signal is usually called geometric noise. Noticeable
developments have been performed in this direction at the Laboratory. It
can be stated with certainty that the developed methods for suppressing
geometric noise essentially decrease its influence via special
algorithms of video signal processing. One of geometric noise filtering
methods is presented in this collection of papers.
The creation of the software for integration of different sensors
is the main nearest task. In this relation it is assumed that
distributed computer network consisting of a low-power PC on board the
robot and a high power PC at the control panel makes it possible to
transfer some simple algorithms to the onboard computer. The task of
analysis of data received from sensors and production of execution
algorithms that should be loaded via the radio channel into the onboard
PC in the form of small codes is performed by the high power PC at the
control panel. In this net the functions of image processing is
distributed between the remote computers that give us more stable system
of all robots (Andreev et al., 2009 and Katalinic & Kordic, 2002).
6. REFERENCES
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