Laser land levelling
1. Agrothessaly: Laser land levelling equipment
1. Agrothessaly: Laser land levelling equipment
The
advent of the laser-controlled land levelling equipment has marked one
of the most significant advances in surface irrigation technology. One
such system is shown in Figure 69. It has four essential elements: (1)
the laser emitter; (2) the laser sensor; (3) the electronic and
hydraulic control system; and (4) the tractor and grading implement.
The
laser emission device, like that pictured in Figure 70, involves a
battery operated laser beam generator which rotates at relatively high
speed on an axis normal to the field plane. This rotating beam thereby
effectively creates a plane of laser light above the field which can be
used as the levelling reference rather than the elevation survey at
discrete grid points in conventional land levelling techniques. Various
beam generators are equipped with self-adjustment mechanisms that allow
the plane of the beam to be aligned in any longitudinal or latitudinal
slope desired.
This reference plane of laser
light is an extremely advantageous factor in the levelling operation
because it is not affected by the earth movement, does not require a
field survey to establish the high and low spots, and does not require
the operator to judge the magnitude of cuts and fills. The distance
between the laser beam and the earth surface is defined such that
deviations from this distance become the cuts and fills. With laser
systems, there is little or no need for the exhaustive engineering
calculations of the conventional approach. The cost of levelling is
usually contracted on the basis of money per equipment hour. The laser
emitter is generally located on a tripod or other tower-like structure
on or near the field and at an elevation such that the laser beam
rotates above any obstructions on the field as well as the levelling
equipment itself. The beam is targeted and received by a light sensor
mounted on a mast attached to the land grading implement. The sensor is
actually a series of detectors situated vertically so that as the
grading implement moves up or down, the light is detected above or below
the centre detector. This information is transmitted to the control
system which actuates the hydraulic system to raise or lower the
implement until the light again strikes the centre detector. It is in
this manner that the sensor on the mast is continually aligned with the
plane on the laser beam and thereby references the moving equipment with
the beam. It is important to note that the sensitivity of the laser
sensor system is at least 10 to 50 times more precise than the visual
judgement and manual hydraulic control of an operator on the tractor.
Consequently, the land levelling operation is correspondingly more
accurate. The skill of the operator is substantially less critical to
the levelling which allows farmers and other personnel access to the
land grading equipment.
source :http://www.fao.org/docrep/t0231e/t0231e08.htm
This reference plane of laser light is an extremely advantageous factor in the levelling operation because it is not affected by the earth movement, does not require a field survey to establish the high and low spots, and does not require the operator to judge the magnitude of cuts and fills. The distance between the laser beam and the earth surface is defined such that deviations from this distance become the cuts and fills. With laser systems, there is little or no need for the exhaustive engineering calculations of the conventional approach. The cost of levelling is usually contracted on the basis of money per equipment hour. The laser emitter is generally located on a tripod or other tower-like structure on or near the field and at an elevation such that the laser beam rotates above any obstructions on the field as well as the levelling equipment itself. The beam is targeted and received by a light sensor mounted on a mast attached to the land grading implement. The sensor is actually a series of detectors situated vertically so that as the grading implement moves up or down, the light is detected above or below the centre detector. This information is transmitted to the control system which actuates the hydraulic system to raise or lower the implement until the light again strikes the centre detector. It is in this manner that the sensor on the mast is continually aligned with the plane on the laser beam and thereby references the moving equipment with the beam. It is important to note that the sensitivity of the laser sensor system is at least 10 to 50 times more precise than the visual judgement and manual hydraulic control of an operator on the tractor. Consequently, the land levelling operation is correspondingly more accurate. The skill of the operator is substantially less critical to the levelling which allows farmers and other personnel access to the land grading equipment.
2. Agrothessaly: Laser land levelling equipment
2. Agrothessaly: Laser land levelling equipment
Two views of land levelling equipment using laser control systems
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