Remote Control System NRC-1
The Minecat Machines was developed by Unipro Automasjon AS in
Halden and Novatron AS was asked to develop a customized remote
control for this machine.
The term "remote control" is however not a correct
description this system as the remote control is just a part of
the functionality. Mainly it is a control system for the machine
that can be operated either by cable (initially for operation
inside the cabin) or by wireless communication. In addition to
communication, the system perform a lot of different functions
such as keeping the speed of the tracks constant during varying
load, adjusting the height of the flail arm for optimal flailing
efficiency and so on. In addition, the system continuously
monitor all engine pressures, temperatures and fluid levels and
trigger operator warnings and alarms if the limits are exceeded.
When critical situations occur, for example excessive engine
temperatures or loss of oil pressure, an automatic and controlled
shutdown of the system is initiated to reduce damage to engines
and hydraulic system. After the immediate shutdown, the operator
can then make an evaluation of the situation and then take
appropriate action, either to either to pull it out of the
minefield by force if necessary or restart the machine and drive
it back out the minefield under strong supervision to a
repair site outside the field.
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Operator Control Panel for Minecat 140/230
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The system is divided into 2 main parts, the central control
system mounted on rubber dampers inside the vehicle, and the
remote operator panel that communicates with the vehicle mounted
equipment by cable or wireless.
The system has two-way communication, sending commands from
the operator to the machine and returning real time status data
back to the operator. All sensors are monitored for alarm and
warnings states locally inside the vehicle and only reported back
to operator when and unormal situation occur. The two way
communication also enable the operator to manually scroll though
the different menus and read out any data that might be of
interest or to change parameters on the fly.
The system uses packet communication with checksum verification
and communicates in the 440-450 MHz band. It has a transmitting
power that allow communication in excess of 1 km (in excess of 10
km free sight). It will however be difficult to operate the
machine over so long distance only based on direct visual
observation. Due to this, an option with wireless video-link was
under preparation, primarily to satisfy special requirements from
military authorities. This option was however not installed on
any vehicle as the project was closed down soon afterwards.
In addition to the remote control functionality, a few simpler
all electronic fuse- and power distribution modules was also
designed to supply the system with power and provide an efficient
and failsafe way of controlling high current consumers such as
starter motors and diesel engine glow plugs (max current up to
130A). These modules was sealed and filled with epoxy resin to
make them less exposed to vibration and environmental influence.
In case of short circuit, the outputs will be instantly switched
off and stay off as long as the problem exists. As soon as the
short circuit is removed, the power will be switched on again
without any need for external interference. Where monitoring is
necessary, a feedback to the control system is provided so that
the operator will be informed of the situation by a warning or an
alarm.
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Solid state fuse and power distribution unit developed for Minecat
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At the end of the project, preparations was also made to
convert the machine into a more autonomous operating vehicle. The
heart of this extension was an autopilot system using a high
accuracy differential-RTK combined GPS/GLONASS positioning system
with a position accuracy of approx. 10 cm (GLONASS is the Prussian
counterpart of GPS). This would have made major improvements to
the clearing accuracy and overall clearing capacity as the
machine would be able to operate under operating conditions (dust
and dark) that would be impossible under human observation and
control. With an autopilot system added, the operator would be
relieved from the tiresome job of continuously steering the
machine for hours under poor visual conditions. Instead, the
operator could now concentrate on planning and setting up the
machines clearing area in addition to supervise the vehicle
during operation and performing regular service (refueling and
replacing air filters).
During autopilot operation, the operator control panel would
be used only for supervising machine status an for handling any
warnings or alarms that may occur. All control of the vehicle
would then be done by the autopilot based on satellite based
positioning with correctional data from a locally placed
reference station. During operation, the machine would send all
positioning data continuously to a laptop computer where the data
would be saved to hard disc and at the same time show a plot of
the cleared area on a map. A printout of the track-plot showing
the cleared area with each individual track visible would provide
documentation of the operation performed. By studying this map, it
can be seen wether 100% of the are had been cleared and that
there was adequate overlap between the adjacent tracks to ensure
that the required safety margins was satisfactory fulfilled.
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