Civil Engineering Reference
In-Depth Information
building an inch or two inside the corner and make a mental note of the measured
distance. Then, carefully move the crosshairs to the corner and take a second shot.
If the distance doesn't change very much, the instrument person will know that
the location is OK. Alternatively, if the accuracy of the building location is not that
important, a point well inside the corner can be located instead of the actual corner.
Because it is not necessary to walk to each location with a prism, reflectorless
EDMs can save a great deal of time when it is necessary to make many locations.
Reflectorless total stations use more battery power than standard EDMs so total
stations with reflectorless technology have the capability to switch back and forth
between the two modes in order to extend battery life.
5.4 Robotic Total Stations
A robotic total station is a total station where the horizontal and vertical axes are
driven by servo motors. They also incorporate communication devices allowing them
to be controlled remotely. The robotic total station does not require that a person be
at the instrument. Instrument controls are located on a data collector carried by the
person who walks around locating physical evidence. The total station locks onto the
prism and tracks it as a person moves from one point to the next. The robot uses its
servo motors to turn the telescope. When the roving person finds evidence that he or
she wants to locate, the prism is placed on the object. The person then presses a button
on the data collector which instructs the robot to measure the angle and distance and
transmit the data to the data collector where the information is stored electronically.
Robotic Total Stations have the potential to be economic in that they theo-
retically allow one person to perform a survey instead of the normal two to four
person crew. However, from a practical point of view, carrying around all the
equipment that surveyors need often takes at least two people anyway. The robotic
total station can be much faster and efficient than a standard total station even if
there is a 2 or 3 person crew.
One disadvantage of the robotic total station becomes apparent when the prism
goes behind a tree or house. The total station will lose its lock on the prism. The rov-
ing person must then initiate a search routine and hope that the total station can find
the prism again. If it doesn't, it may be necessary to walk back to the total station in
order to regain lock. Some total stations are better than others in maintaining lock.
Of course, this is not an issue if there is a person standing at or near the total station.
5.5 Servo Driven Total Stations
Somewhere between a robotic total station and a conventional total station lies the
Tracking Total Station
. It is similar to the robot except it does not use a radio to
communicate data to a remote data collector. Instead, the data collector is located at
