The boom is comprised of two
sections: (1) the main boom, which is positioned and attached over the
truck bed; (2) the extension boom, which is attached to the main boom
by a hinge and swings out over the bridge for taking measurements. For
transporting the system to the site, the extension boom is folded in
and secured to the main boom. The truck is maneuvered adjacent to the
bridge rail to conduct measurements.
Two winches are mounted on the main
boom over the truck bed. The top winch controls the position of a
trolley along the length of the boom, thus determining how far out
from the bridge rail the sonar sensor is to be suspended. The bottom
winch tethers the sonar assembly, lowering it into the water and
hoisting it back to the boom. Both winches are operated by pistol-grip
controllers.
Mounted also on the main boom is a
water stage sensor that measures the distance from the stage sensor to
the water surface. Two other sensors provide additional necessary
information to determine the location of the streambed point being
measured in relation to a known point on the bridge. These two sensors
are (1) a truck wheel position sensor and (2) a trolley position
sensor. The truck wheel position sensor provides the relative position
of the truck from a known point on the bridge, and the trolley
position sensor provides the distance that boom’s trolley extends
over the bridge rail.
The three-dimensional location of the
streambed point being measured is therefore determined from (1) the
distance from the sonar sensor to the streambed, (2) the distance from
the boom to the water as determined by the stage sensor, (3) the
distance of the suspension trolley from its home position as
determined by the trolley position sensor, and (4) the position of the
truck from a known point on the bridge as determined by the truck
wheel position sensor.
A sonar profiler electronics module
is mounted to the sonar sensor assembly. The module’s enclosure
houses the sonar sensor’s electronics interface and cabling to the
sonar sensor, a battery, and a wireless data link transmitter. The
wireless data link transmits the distance from the sensor to the
streambed once each second to a receiver in the portable attaché case
described next.
Included with the system is a
portable attaché case that includes a wireless data link receiver; a
data controller electronics module; a control panel with a power
switch, a push button (labeled Data Marker) for resetting the system
reference points, receptacles for cables from the stage, trolley, and
truck wheel sensors; a 9-pin RS232 port; and a Personal Data Assistant
(PDA) PC.
Sonar sensor data is transferred via
the wireless data link to the electronics module. The stage sensor,
the trolley sensor, and the truck wheel position sensor are all
directly cabled to receptacles on the attaché case’s control panel.
A push-button controller is provided
that has a button which, when pressed, causes an additional sequential
data field to be written to the system’s data record. This
controller is cabled to the attaché case control panel receptacle
marked "Manual." This will assist in marking a specific
location at which the streambed depth is measured
The electronics module outputs data
records to the PDA via the 9-pin RS232 port, which displays the data
in tabular form on the screen and stores the data on a 32 meg memory
card. Upon completion of a survey the data can be downloaded from the
memory card to a PC for final reduction and analysis. The PC program,
provided by the user, must have software routines that will (1)
convert truck wheel rotations from the trolley position sensor and the
truck wheel sensor to distances, and (2) integrate all data from the
sonar, stage, trolley, and truck wheel sensors to a point in three
dimensional space.
The Mobile Wireless Streambed
Profiler is one of a family of electronic measurement systems designed
and distributed by ETI Scour Measurement Systems that accommodate a
variety of requirements and environments.
(Back to
Truck Scour Monitors)
ETI's
mobile, light-truck-mounted, wireless streambed profiler uses an active
sonar sensor that measures distance from the sonar transducer to the
streambed.