U.S. patent application number 11/790205 was filed with the patent office on 2008-10-30 for towed compaction determination system utilizing drawbar force.
This patent application is currently assigned to CATERPILLAR INC.. Invention is credited to Paul Thomas Corcoran.
Application Number | 20080267719 11/790205 |
Document ID | / |
Family ID | 39887164 |
Filed Date | 2008-10-30 |
United States Patent
Application |
20080267719 |
Kind Code |
A1 |
Corcoran; Paul Thomas |
October 30, 2008 |
Towed compaction determination system utilizing drawbar force
Abstract
A compaction determination system for monitoring the compaction
in a material produced by a rotary device as the rotary device is
towed over the material is disclosed. The compaction determination
system may have a force sensor associated with a drawbar used to
tow the rotary device, the force sensor being configured to sense a
force transmitted to the rotary device via the drawbar. The
compaction determination system may further have a controller in
communication with the force sensor. The controller may be
configured to determine a compaction of the material produced by
the rotary device based on the sensed force.
Inventors: |
Corcoran; Paul Thomas;
(Washington, IL) |
Correspondence
Address: |
CATERPILLAR/FINNEGAN, HENDERSON, L.L.P.
901 New York Avenue, NW
WASHINGTON
DC
20001-4413
US
|
Assignee: |
CATERPILLAR INC.
|
Family ID: |
39887164 |
Appl. No.: |
11/790205 |
Filed: |
April 24, 2007 |
Current U.S.
Class: |
405/271 |
Current CPC
Class: |
E02D 3/039 20130101;
E01C 19/288 20130101; E01C 19/266 20130101 |
Class at
Publication: |
405/271 |
International
Class: |
E01C 19/23 20060101
E01C019/23 |
Claims
1. A compaction determination system for monitoring the compaction
in a material produced by a rotary device as the rotary device is
towed over the material, comprising: a force sensor associated with
a drawbar used to tow the rotary device, the force sensor being
configured to sense a force transmitted to the rotary device via
the drawbar; and a controller in communication with the force
sensor, the controller being configured to determine a compaction
of the material produced by the rotary device based on the sensed
force.
2. The compaction determination system of claim 1, wherein the
controller determines a higher compaction of the material when the
sensed force is lower, and determines a lower compaction of the
material when the sensed force is higher.
3. The compaction determination system of claim 1, further
including an incline sensor configured to sense an incline in a
surface of the material, wherein the controller is in communication
with the incline sensor and configured to determine the compaction
of the material produced by the rotary device based further on the
sensed incline.
4. The compaction determination system of claim 3, wherein the
controller determines a higher compaction for a given sensed force
when a decline is sensed, and determines a lower compaction for the
given sensed force when an incline is sensed.
5. The compaction determination system of claim 1, wherein the
controller is further configured to display within the mobile
machine a representation of the determined material compaction.
6. The compaction determination system of claim 1, wherein the
controller determines compaction by comparing the sensed force to a
target value.
7. The compaction determination system of claim 1, wherein the
controller determines compaction by comparing the force sensed
during a current compaction pass to a force sensed during a
previous compaction pass.
8. A method of determining compaction, comprising: towing a rotary
device over a material to compact the material; sensing a force of
the towing; and determining an amount of compaction created by the
rotary device based on the sensed force.
9. The method of claim 8, wherein the amount of compaction is
determined to be higher when the sensed force is lower, and the
amount of compaction is determined to be lower when the sensed
force is higher.
10. The method of claim 8, further including sensing an incline in
the surface of the material, wherein the amount of compaction is
determined based further on the sensed incline.
11. The method of claim 10, wherein the amount of compaction is
determined to be higher for a given sensed force when a decline is
sensed, and the amount of compaction is determined to be lower for
the given sensed force when an incline is sensed.
12. The method of claim 8, further including visually displaying a
representation of the determined material compaction.
13. The method of claim 8, wherein determining includes comparing
the sensed force to a target value.
14. The method of claim 8, wherein determining includes comparing
the force sensed during a current compaction pass to a force sensed
during a previous compaction pass.
15. A surface compaction system, comprising: a machine; a rotary
device pulled by the machine over a material to compact the
material; a drawbar connecting the rotary device to the machine; a
force sensor associated with the drawbar being configured to sense
a force transmitted from the machine to the rotary device via the
drawbar; an inclinometer configured to sense an incline in a
surface over which the rotary device is operating; and a controller
in communication with the force sensor and the inclinometer, the
controller being configured to determine a compaction of the
material produced by the rotary device based on the sensed force
and the sensed incline.
16. The surface compaction system of claim 15, wherein the
controller determines a higher compaction of the material when the
sensed force is lower, and determines a lower compaction of the
material when the sensed force is higher.
17. The surface compaction system of claim 15, wherein the
controller determines a higher compaction for a given sensed force
when a decline is sensed, and determines a lower compaction for the
given sensed force when an incline is sensed.
18. The surface compaction system of claim 15, wherein the
controller is further configured to display within an operator
station of the machine a representation of the determined material
compaction.
19. The surface compaction system of claim 15, wherein the
controller is configured to determine compaction by comparing the
sensed force to a target value.
20. The surface compaction system of claim 15, wherein the
controller is configured to determine compaction by comparing the
force sensed during a current compaction pass to a force sensed
during a previous compaction pass.
Description
TECHNICAL FIELD
[0001] The present disclosure relates generally to a compaction
determination system, and more particularly, to a system for
determining material compaction levels based on the drawbar force
of a towed compactor.
BACKGROUND
[0002] Compaction machines are utilized in the construction of road
beds, pavements, foundations, dams, runways, landfills, and other
projects. In order to ensure that these projects meet required
standards of load bearing, strength, durability, space, and
permeability, the materials used in the construction process must
be sufficiently compacted. Thus, tight control over the compaction
process is required.
[0003] One way to control the compaction process is to periodically
measure a level of compaction resulting from the process as the
project progresses. That is, if a low compaction level is measured,
additional compaction is provided until a stipulated level of
compaction is attained. Common ways to measure compaction levels
include impacting the material surface and measuring an indentation
resulting from the impact, moving a tipped roller over the surface
and measuring a distance off of the surface that the roller raises
as a result of tip penetration being less than tip length,
penetrating a surface with a predefined instrument and force and
then measuring the penetration depth, and measurements of the
density of a compacted layer of material with devices such as a
nuclear density gauge. However, each of these methods have
associated negative aspects such as cost, destruction of the
finished surface, excessive time consumption, and being labor
intensive.
[0004] One way to quickly and economically determine soil hardness
is disclosed in U.S. Pat. No. 6,041,582 (the '582 patent) issued to
Tiede et al. on Mar. 28, 2000. The '582 patent discloses a faring
system for performing work on an agricultural field, while
compaction conditions of the field are being recorded. The farming
system includes an agricultural tractor equipped with ground
penetrating farm tools such as a plow, an "S" shaped tine, a coil
shank tool, or a sub-soil ripper. The tractor pulls the tool
through the soil by way of a drawbar or hitch. A strain gauge is
connected to the drawbar and, based on a measurement of force
imparted by the tools to the soil provided by the strain gauge,
soil compaction or hardness of the tilled field is calculated and
recorded. From this data, a map is generated that shows varying
compaction or hardness of the field, which can be utilized to
effect farming practices such as tillage depth, fertilizing,
seeding, watering, and the application of insecticides and
herbicides.
[0005] Although the faring system of the '582 patent may provide a
quick and economical way to determine compaction of an agricultural
field, its accuracy and use may be limited. Specifically, because
the only input is drawbar force, an incline or decline could
significantly affect the measured force, resulting in an inaccurate
representation of soil compaction or hardness at a particular
location. For example, when operating the tractor up an incline,
the drawbar strain gauge may read high levels of force and
associate this force with high compaction, even though a
significant portion of the measured force may be due to gravity
acting on the farm tool. Similarly, when operating the tractor down
all incline, the drawbar strain gauge may read low levels of force
and associate this force with low compaction, even though gravity
may again be acting on the farm tool to lessen the measurement.
Further, because the drawbar force measured by the strain gauge is
related to the force required to move a tool through soil, only
applications allowing a disruption of the surface may benefit from
the farming system. That is, when creating a roadway, a measurement
system that requires a tool be ripped through the surface of the
roadway may be undesirable.
[0006] The disclosed machine system is directed to overcoming one
or more of the problems set forth above.
SUMMARY OF THE DISCLOSURE
[0007] In one aspect, the present disclosure is directed to a
compaction determination system for monitoring the compaction in a
material produced by a rotary device as the rotary device is towed
over the material. The compaction determination system may include
a force sensor associated with a drawbar used to tow the rotary
device, the force sensor being configured to sense a force
transmitted to the rotary device via the drawbar. The compaction
control system may further include a controller in communication
with the force sensor. The controller may be configured to
determine a compaction of the surface produced by the rotary device
based on the sensed force.
[0008] In another aspect, the present disclosure is directed to a
method of determining compaction of a material. The method may
include towing a rotary device over a material to compact the
material. The method may also include sensing a force of the
towing, and determining an amount of compaction created by the
rotary device based on the sensed force.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a diagrammatic illustration of an exemplary
disclosed machine;
[0010] FIG. 2 is a schematic and diagrammatic illustration of an
exemplary disclosed control system for use with the machine of FIG.
1;
[0011] FIG. 3 is a flowchart depicting an exemplary disclosed
method performed by the compaction determination system of FIGS. 1
and 2; and
[0012] FIG. 4 is flowchart depicting another exemplary disclosed
method performed by the compaction determination system of FIGS. 1
and 2.
DETAILED DESCRIPTION
[0013] FIG. 1 illustrates an exemplary embodiment of a machine 10.
Machine 10 may be a mobile machine that perform some type of
operation associated with an industry such as mining, construction,
farming, or any other industry known in the art. For example,
machine 10 may be an earth moving machine such as a track type
tractor, a wheeled tractor, or any other suitable
operation-performing machine. Machine 10 may include a power source
12 and at least one traction device 14. Machine 10 may also have an
operator cabin 16 for manual control of power source 12 and
traction device 14.
[0014] Power source 12 may embody an engine such as, for example, a
diesel engine, a gasoline engine, a gaseous fuel powered engine
such as a natural gas engine, or any other type of engine apparent
to one skilled in the art. Power source 12 may alternatively embody
a non-combustion source of power such as a fuel cell, a power
storage device, an electric motor, or other similar mechanism.
Power source 12 may be connected to drive traction device 14,
thereby propelling machine 10.
[0015] Traction device 14 may include tracks located on each side
of machine 10 (only one side shown). Alternately, traction device
14 may include wheels, belts or other known traction devices.
Traction device 14 may transmit power from power source 12 to a
ground surface.
[0016] Operator cabin 16 may contain operator controls and
instruments that show various information on the operational status
and modes of machine 10. For example, operator cabin 16 may, if
desired, contain one or more interface devices 40 as described
below in reference to FIG. 2.
[0017] Towed compactor 20 may include a drawbar 22 and a rotary
compactor 24. Drawbar 22 may transmit force from machine 10 to
rotary compactor 24. Rotary compactor 24 may be any rotary
compactor known in the art, such as, for example, a smooth solid
roller, a smooth hollow roller designed to be filled with ballast,
or a tipped roller as shown. Rotary compactor 24 may compact
material by using its weight to compress the material as rotary
compactor 24 is towed over the material. Smooth rollers may provide
compression from the top of the material, while tipped rollers may
offer additional internal compression of the material due to the
action of the tips as they penetrate the surface of the material.
Rotary compactor 24 may additionally include a vibratory mechanism,
if desired.
[0018] As illustrated in FIG. 2, machine 10 may include an
attachment means 18, for attaching towed implements, such as towed
compactor 20. Attachment means 18 may be any attachment means known
in the art for attaching towed implements, such as, for example, a
single-point hitch, a thee-point hitch, or an articulated joint.
Attachment means 18 may also include a means known in the art (not
shown) for providing electrical power to the towed implement and/or
for two-way communication of control signals with towed implement
20.
[0019] A compaction determination system 28 may be associated with
towed compactor 20 to determine an effectiveness of rotary
compactor 24 based on a sensed force. Compaction determination
system 28 may include a force sensor 32, an inclinometer 34, a
position determining unit 38, a display 40a, an input 40b, and a
controller 30. Controller 30 may receive communication from force
sensor 32, inclinometer 34, position determining unit 38, and input
40b, and may send communication to display 40a responsive to the
received communications.
[0020] Force sensor 32 may be associated with drawbar 22 to sense a
force on towed compactor 20 and to generate a signal in response
thereto. Force sensor 32 may be any force sensor commonly known in
the art, such as, for example, a load link, a strain gauge, a
transducer, or a load cell. Force sensor 32 may optionally include
temperature compensation means commonly known in the art. For
example, if force sensor 32 comprises strain gauges, the strain
gauges may be configured in the form of a Wheatstone bridge to
compensate for temperature-induced strain that may affect a
reporting of the true drawbar force. The force reported by force
sensor 32 may be indicative of the force required for machine 10 to
pull towed compactor 20 over the material to be compacted when
machine 10 is driven at a constant speed. A lower force reported by
force sensor 32 may be indicative of a more compact material, while
a higher force reported by force sensor 32 may be indicative of a
less compact material.
[0021] Inclinometer 34 may be associated with drawbar 22 to sense
an incline of towed compactor 20 and to generate a signal in
response thereto. Alternatively, inclinometer 34 may be located on
machine 10, if desired. The incline of towed compactor 20 may
correspond with the slope of a surface over which towed compactor
20 is being towed. Alternatively, any other incline or slope sensor
known in the art may be used. Controller 30 may use the incline of
towed compactor 20 to calculate a resultant force on the drawbar
associated with the incline, and subsequently to determine a true
draft force on drawbar 22.
[0022] Position determining unit 38 may be associated with towed
compactor 20 to determine the location of towed compactor 20.
Alternatively, position determining unit 38 may be located on
machine 10, if desired. Position determining unit 38 may be GPS
based, laser based, or utilize any other technology commonly known
in the art. Position determining unit 28 may be used by controller
30 to determine the location of towed compactor 20. Controller 30
may also or alternatively use position determining unit 38 to
create a visual representation of the area to be compacted on
display 40a and to show the location of the towed compactor 20 and
the measured compaction in that area.
[0023] Display 40a may be located within the operator cabin 16 of
machine 10 for viewing by the machine operator, or it may be an
external display of the type commonly known in the art that is
connected to a display port (not shown) of controller 30.
Alternatively, display 40a may be in wireless communication with
controller 30 and located elsewhere, including a location remote
from towed compactor 20 and machine 10. Display 40a may comprise
one or more cathode ray tubes (CRT), liquid crystal displays (LCD),
plasma displays, or another device that is capable of displaying
graphics and/or text. Display 40a may receive data from controller
30 and display the data for an operator of machine 10. Preferably,
the displayed data may be relevant to the amount of compaction
currently being generated, such as, for example, the force required
to pull towed compactor 20 as it moves over the material. In
addition, display 40a may indicate the location of towed compactor
20 in real time geographic coordinates. The displayed information
may be graphical, text, tabular, numeric, and or any other format
desired to effectively display the desired data.
[0024] Input 40b may be located on the towed compactor 20, within
the operator cabin 16 of the machine 10 for use by the machine
operator, or located remotely from towed compactor 20. Input 40b
may include a wide variety of devices configured to input data into
controller 30. For example, input device 40b may include a
keyboard, a mouse, a joy-stick, a touch-screen, a disk drive, a
magnetic card reader, a scanner, a CD drive, a DVD drive, a floppy
disk drive, a memory stick input, a USB port, or any other suitable
device. Input 40b may be used to input data such as results from
proof compaction tests done on-site or in a laboratory, coordinates
or other information describing the site to be compacted, weather
information, information describing the type and condition of the
material to be compacted, moisture content of the material to be
compacted, desired measurement intervals, compactor width,
compactor weight, compactor diameter or other parameters of rotary
compactor 24, and date and time.
[0025] Controller 30 may embody a single microprocessor or multiple
microprocessors that include a means for controlling an operation
of the disclosed compaction determination system. Numerous
commercially available microprocessors can be configured to perform
the functions of controller 30 and it should be appreciated that
controller 30 could readily embody a general machine microprocessor
capable of controlling numerous machine functions, including
sending and receiving control and data signals. Controller 30 may
include a memory, a secondary storage device, a processor, wireless
communication circuitry, external connection ports, and/or any
other components for running an application. Various other circuits
may be associated with controller 30 such as power supply
circuitry, signal conditioning circuitry, solenoid driver
circuitry, and/or other types of circuitry.
[0026] Controller 30 may be in communication with the various
components of compaction determination system 28. In particular,
controller 30 may be in communication with force sensor 32,
inclinometer 34, position determining unit 38, display 40a, and
input 40b via communication lines 44, 46, 48, 50, and 52,
respectively. Controller 30 may receive and store in memory for
subsequent display or calculation the signals from each of force
sensor 32, inclinometer 34, and position determining unit 38.
Controller 30 may receive and store data and commands from input
40b, and send signals to display 40a in response to received
signals and calculations performed on data stored in the memory.
Controller 30 may perform calculations on data received or stored
in memory, and store the results of the calculations in memory for
use in subsequent calculations, for display on display 40a, or for
use in future compaction events.
[0027] Controller 30 may perform a variety of calculations. For
example, using the incline reported by inclinometer 34 and the
weight of towed compactor 20, which may be provided by the
manufacturer or obtained by measurement, controller 30 may use
Equation 1 below to calculate the incline force on drawbar 22 that
is a result of an uphill or downhill incline of towed compactor
20:
IF=sin .alpha.*W (Equation 1)
where IF is the incline force, .alpha. is the angle of incline
reported by inclinometer 34, and W is the weight of towed compactor
20. The angle of incline may have a positive value for uphill
inclines, and a negative value for downhill inclines.
[0028] Controller 30 may then combine the calculated incline force
with the drawbar force reported by force sensor 32 to determine the
true draft force on drawbar 22 using Equation 2 below:
DF=SF-IF (Equation 2)
where SF is the drawbar force reported by force sensor 32 and DF is
the true draft force. Controller 30 may store the results of these
calculations in memory, and/or display them on display 40a.
[0029] Controller 30 may compare the results of calculations with
target values or the results of prior calculations. For example,
controller 30 may compare the draft force with a target draft force
value stored in memory and/or supplied from the input 40b to
determine whether the draft force is less than, equal to, or
greater than the target draft force. If the calculated draft force
is greater than the target draft force, additional passes of the
area may be required. However, if the calculated draft is less than
or equal to the target draft force, it can be concluded that
compaction of that area is complete. Controller 30 may store the
results of this calculation in memory, and/or display them on
display 40a.
[0030] Alternatively, controller 30 may compare the draft force
calculated for a current compacting pass of a specific area with
the draft force calculated during a previous compacting pass of the
same area, to determine the difference in draft force between the
two passes using Equation 3 below:
.DELTA.DF=DF(n-1)-DF(n) (Equation 3)
where .DELTA.DF equals a differential draft force, DF(n) equals the
draft force on a current pass, and DF(n-1) equals the draft force
on a previous pass. Controller 30 may then determine whether this
differential draft force is less than, equal to, or greater than a
target differential draft force stored in memory. If the calculated
differential draft force is greater than a target differential
draft force, it may be concluded that the material has not yet been
compacted as fully as desired, and additional passes of the area
may be required. However, if the calculated differential draft
force is less than or equal to a target differential draft force,
it may be concluded that the material has reached the desired
compaction level. Controller 30 may store the results of this
calculation in memory, and/or display them on display 40a.
[0031] Controller 30 may allow for input of a desired measurement
interval. The measurement interval may be defined by a measure of
length, such as, for example, one foot, one meter, or a length
equivalent to the circumference of rotary compactor 24. Controller
30 may use the measurement interval to virtually subdivide a
compaction site area and define the resolution of the compaction
determination. For example, controller 30 may use the measurement
interval as a trigger for when to record and store data by
receiving data from position determining unit 38 and comparing that
data to the stored value of the measurement interval. When
controller 30 determines that rotary compactor 24 has traveled a
distance equal to the measurement interval, controller 30 may then
take a snapshot of the data being recorded from force sensor 32,
inclinometer 34, and position determining unit 38, and use the
sensed values at the tine of that snapshot as values for that
measurement interval. Alternatively, controller 30 may use any
sampling technique known in the art to continuously record and
store data while rotary compactor 24 traverses each measurement
interval, and then calculate an average value of the data recorded
and stored from force sensor 32, inclinometer 34, and position
determining unit 38 as the values for the measurement interval
while traversing that measurement interval.
[0032] The memory of controller 30 may contain a virtual map of an
area to be compacted. The data contained in the virtual map may be
received from the input of controller 30, or it may be generated by
controller 30 during operation of machine 10. For example, the
virtual map may contain the boundaries of the area to be compacted.
The boundaries may be input by several methods, including, for
example, by driving machine 10 around the boundary of an area and
obtaining the coordinates of the boundaries from position
determining unit 38, inputting the boundaries manually by taking
measurements of the area, downloading the boundaries of the area
from data obtained during previous compaction activities, or
downloading from commercial mapping services. The virtual map may
also contain data such as site topography, material composition,
moisture content, and other environmental conditions.
[0033] The memory of controller 30 may also contain compaction data
about the material derived from on-site or laboratory tests. The
data may, for example, contain information about the desired
compaction amount of the material and the draft force required to
tow rotary compactor 24 over material in that compaction state.
Such data may be used as target values for comparison with
calculated values of the draft force.
[0034] Controller 30 may control display 40a to display a variety
of compaction information in a variety of ways. For example,
controller 30 may display the virtual map on display 40a and use
information from position determining unit 38 to display a
representation of towed compactor 20 on the virtual map. Controller
30 may update this display in real-time as towed compactor 20 is
towed around the compaction area. Controller 30 may also display on
display 40a data recorded during compaction, as well as results of
compaction after controller 30 determines that compaction is
complete or as compaction progresses.
[0035] FIG. 3 shows a flowchart illustrating an exemplary method of
operating compaction determination system 28 in a first mode. In
this first operating mode, compaction determination system 28 may
determine compaction of a material based on a proof test performed
on a small portion of a compaction site. A compaction specification
for this method of operation may include a predetermined compaction
level in any terms commonly known in the art, such as, for example,
the desired density of a material, as determined by a Proctor test.
To perform the proof test, towed compactor 20 may be used to fully
compact a small test area of the compaction site. Compaction may be
determined using any compaction verification method commonly known
in the art to determine that the compaction of the material in the
test area of the site satisfies the compaction specifications.
After it is verified that the compaction in the test area is
complete, towed compactor 20 may be towed once more over the
compacted test area, and controller 30 may determine the draft
force required to tow rotary compactor 24 over the compacted
material. Controller 30 may then store this draft force for use as
a target value to determine when the remaining portions of the
compaction site are compacted to the specified level within a
specified range, such as, for example, .+-.5%.
[0036] The embodiment illustrated in FIG. 4 shows a second
operating mode of compaction determination system 28. In this
second operating mode, compaction determination system 28 may
determine compaction of a material based on a comparison of a
calculated draft force on towed compactor 20 between successive
passes. A compaction specification for this method of operation may
specify, for example, that a rotary compactor of a certain weight
is to be towed over a compaction site until a differential draft
force is about equal to a desired differential draft force. The
compaction specification may specify that a desired compaction is
attained when the difference in draft force between a current pass
and the previous pass over the material is about equal to a target
value. Compaction determination system 28 may determine the
differential draft force between two successive passes, and
determine if the differential draft force is within a specified
range of the target differential draft, such as, for example,
within about .+-.5%.
[0037] FIGS. 3 and 4 will be described in detail below to further
illustrate aspects of the disclosed system.
INDUSTRIAL APPLICABILITY
[0038] The disclosed compaction determination system may be
applicable to any towed compactor where quantifiable and repeatable
control of material compaction is desired. Particularly, the
disclosed compaction determination system may provide a simple,
reliable way to determine the amount of material compaction based
on the draft force required to tow a towed compactor, without
requiring destruction or penetration of the compacted material. The
operation of compaction determination system 28 will now be
described.
[0039] Towed compactor 20 may be attached to machine 10 through
attachment means 18. An operator may then operate machine 10 and
pull towed compactor 20 over a compaction area containing a
material to be compacted. The operator may make one or more passes
over the compaction area, such that the number of passes is
sufficient to compact the material to a predetermined level, as
determined by an operating mode of compaction determination system
28. Each pass may generally correspond to the width of rotary
compactor 24, attempting to minimize overlap among contiguous
passes, and ensuring that no area is left uncompacted. Controller
30 may use position determining unit 38 to determine that the
entire compaction area reaches the desired compaction level, and
alert an operator of machine 10 through display 40a as to the
results of compaction.
[0040] As illustrated in FIG. 3, controller 30 may receive and
store in memory any necessary information associated with the
current compacting operation, such as, for example, the boundaries
of the area to be compacted, a desired measurement interval, a
desired compaction amount, and any other information necessary to
describe the compaction site (Step 100). The boundaries may be
defined by, for example, inputting into controller 30 through input
40b a description of the area using GPS coordinates, Cartesian
coordinates, latitude and longitude, or any other coordinate system
sufficient to describe the area. Alternatively, the boundaries may
be input by driving machine 10 and towed compactor 20 around the
boundary of the area to be compacted, while controller 10 receives
and stores data from position determining unit 28 sufficient to
define the boundaries of the area. Other information that the
operator may input include, for example, material type, material
moisture content, date, time, and weather information.
[0041] Step 100 may be better understood through an example. In
this example, controller 30 receives various data about a
particular compaction site, including a weight of rotary compactor
24 being 10000 lb, a width of rotary compactor 24 being 6 feet, a
measurement interval being 15 feet, the boundaries of the site in
GPS coordinates, the material type being clay, the moisture content
as measured on site, and the date and time.
[0042] Controller 30 may then receive and store in memory
calibration data such as, for example, the draft force on drawbar
22 reported by force sensor 32, the incline of towed compactor 20
reported by inclinometer 34, and the position of towed compactor 20
reported by position determining unit 38 (Step 102). The data may
be received as the operator drives machine 10 with attached towed
compactor 20 over material in a test area, which may be a smaller
subdivision of the compaction site. In addition to receiving and
storing the calibration data into memory, controller 30 may create
associations in memory among the various parameters, such as, for
example, an association that a specific drawbar force, incline, and
distance traveled are associated with a specific location or region
of the compaction site. These associations may be used by
controller 30 to calculate accurate determinations of the amount of
compaction, as well as to provide visual representations of the
amount of compaction on display 40a. The data stored during this
step may be used for various calculations and visual
representations, including, for example, calculations by controller
30 to predict and determine the performance of rotary compactor 24
during compaction of the entire compaction site.
[0043] After it is verified by compaction verification means known
in the art that the compaction value of the test site satisfies the
compaction specification, controller 30 may receive and store in
memory data such as, for example, the force on drawbar 22 reported
by force sensor 32, the incline of towed compactor 20 reported by
inclinometer 34, and the position of towed compactor 20 reported by
position determining unit 38, as towed compactor 20 is towed over
the compacted test area. Controller 30 may then calculate the draft
force on towed compactor 20 using Equations 1 and 2. Controller 30
may store this draft force as a target value for the compaction of
the remainder of the compaction site.
[0044] Continuing with the example from step 100 above, the test
area is determined to be a small area the width of towed compactor
20 (6 feet), and the length of the measurement interval (15 feet).
After verifying that the desired compaction value of the test area
has been reached, towed compactor 20 is towed over the test area
once again. During this final pass, controller 30 receives a force
measurement of 2700 lb from force sensor 32, and an incline
measurement of 4 deg. from inclinometer 34. Controller 30 then uses
Equation 1 to calculate an incline force of 698 lb, and Equation 2
to calculate a draft force of 2002 lb that accounts for the
incline. Controller 30 then stores the 2002 lb value as the target
draft force for use in later compaction level determinations.
[0045] Controller 30 may receive and store in memory operational
data such as, for example, the force on drawbar 22 reported by
force sensor 32, the incline of towed compactor 20 reported by
inclinometer 34, and the position of towed compactor 20 reported by
position determining unit 38, as towed compactor 20 makes one or
more passes over the entire compaction site (Step 104). In addition
to receiving and storing the operational data in the memory,
controller 30 may create associations in memory among the various
parameters, such as, for example, an association among a drawbar
force, incline, distance traveled and location or region of the
compaction site. These associations may be used by controller 30 to
accurately calculate the amount of compaction of the site, as well
as to provide visual representations of the amount of compaction on
display 40a.
[0046] Controller 30 may use the operational data received and
stored in step 104 to calculate the draft force on towed compactor
20 for the entire compaction site (Step 106). Controller 30 may
first use Equation 1 to calculate the incline force on the towed
compactor, and then Equation 2 to calculate the draft force on
towed compactor 20. Controller 30 may then compare the draft force
calculated using Equation 2 to the target draft force value stored
during step 102. Controller 30 may perform these calculations and
comparisons for each pass of each subdivision of the compaction
site, as defined by the measurement interval. Controller 30 may
store in memory the results for each pass of each subdivision. When
controller 30 determines that the draft force on the most recent
pass is greater than the target draft force, then controller 30 may
signal the operator that compaction is not yet complete, and that
one or more passes may still be required (return to Step 104). When
controller 30 determines that the draft force on the most recent
pass is less than or equal to the target draft force, then
controller 30 may determine that compaction is complete. Controller
30 may evaluate the results of the comparison of the draft force
using a range of acceptable compaction, such as, for example,
.+-.5% of the desired compaction level.
[0047] Continuing with the example from steps 100 and 102,
controller 30 receives a force measurement of 8500 lb from force
sensor 32, and an incline measurement of 6 deg. from inclinometer
34 during a particular measurement interval. Controller 30 then
uses Equation 1 to calculate an incline force of 1045 lb, and
Equation 2 to calculate a draft force of 7455 lb that accounts for
the incline. In Step 106, controller 30 determines that the
calculated draft force of 7455 lb is greater than the target draft
force of 2002 lb determined in Step 102, and therefore compaction
is not yet complete (return to Step 104). In Step 104, on the
second pass of a particular area, moving in the opposite direction,
controller 30 receives a force of 980 lb from force sensor 32, and
an incline of -6 deg. from inclinometer 34. Controller 30 then uses
Equation 1 to calculate an incline force of -1045 lb, and Equation
2 to calculate a draft force of 2025 lb that accounts for the
incline. In Step 106, controller 30 then determines that the
calculated draft force of 2025 lb is within .+-.5% of the target
draft force of 2002 lb, and therefore that compaction is
complete.
[0048] Once controller 30 has determined that compaction is
complete, controller 30 may display compaction information on
display 40a for each subdivision (Step 108). This information may
be used by the operator in determining which subdivisions of the
compaction area may still need one or more passes of rotary
compactor 24 to achieve the desired compaction. After controller 30
determines that the compaction level of the entire compaction site
has reached the desired value, controller 30 may gather and store
the final information about the compaction as an archive file
within its memory. Controller 30 may display the information on
display 40a, and/or download or otherwise record it using any
apparatus commonly known in the art for downloading and/or
recording data. This downloaded and/or recorded data may be used in
future compaction activities and/or as quality control or quality
assurance of the compaction activities in validation that the
proper compaction level has been achieved.
[0049] Continuing the example from the preceding steps, in Step
108, controller 30, having determined that the calculated draft
force of 2025 lb is within the specified range of the target draft
force of 2002 lb, determines that compaction is complete.
Controller 30 then displays information on display 40a to notify
the operator that compaction of the area is complete, and then
stores the data for later use.
[0050] The second operating mode of compaction determination unit
38 shown in FIG. 4 will now be described. Controller 30 may receive
and store in memory any necessary information associated with the
current compacting operation, as described above in Step 100 (Step
200).
[0051] Step 200 may be better understood through an example.
Controller 30 receives various data about a compaction site as
described in Step 100 above. In addition, a target differential
draft force of 500 lb is entered, as compaction may be determined
to be complete when, according to the compaction specification, the
differential draft force between two passes is less than about 500
lb, within a range of .+-.5%.
[0052] Controller 30 may then receive and store in memory
operational data as described in Step 104 above (Step 202).
Controller 30 may use the operational data received and stored in
step 202 to calculate a differential draft force experience by
compactor 20 between passes (Step 204). Controller 30 may use
Equation 1 to calculate the incline force on the towed compactor,
and Equation 2 to calculate the draft force on towed compactor 20
to account for the incline. Controller 30 may then use Equation 3
to compare the draft force of the current compacting pass over a
single subdivision to the draft force for the previous compacting
pass over that same subdivision. When controller 30 determines that
the differential draft force after the current pass is greater than
the target differential draft force, controller 30 may signal the
operator that compaction is not yet complete, and that one or more
passes may still be required (return to Step 202). However, when
controller 30 determines that the differential draft force after
the current pass is less than or equal to the target differential
draft force, then controller 30 may determine that compaction is
complete. Controller 30 may evaluate the results of the comparison
of the differential force using a range, such as, for example,
.+-.5%, as specified by the compaction specification.
[0053] Continuing the example from step 200, on pass 1 of a
subdivision of the compaction site, controller 30 receives data
from force sensor 32 reporting a force measurement of 8500 lb and
inclinometer 34 reporting an incline measurement of 6 degrees.
Controller 30 uses Equation 1 to calculate an incline force of 1045
lb, and then uses Equation 2 to calculate the draft force to be
7455 lb that accounts for the incline. In Step 204, because this
was the first pass, controller 30 cannot compare the calculated
draft force to the draft force from the previous pass, so
controller 30 stores the calculated draft force value and returns
to step 202. In step 202, on pass 2, controller 30 receives data
from force sensor 32 reporting a force measurement 980 lb and
inclinometer 34 reporting an incline measurement of -6 degrees.
Controller 30 then uses Equation 1 to calculate an incline force of
-1045 lb, and Equation 2 to calculate the draft force to be 2025 lb
that accounts for the incline. In step 204, controller 30 uses
Equation 3 to determine that the differential draft force between
pass 1 and 2 is 5429 lb. Because controller 30 calculates this
differential draft force is greater than the target differential
force of 500 lb, controller 30 stores the draft force value of 2025
lb for pass 2 and returns to step 202. In Step 202, on pass 3 of
the same area, controller 30 receives data from force sensor 32
reporting a force measurement of 2750 lb and inclinometer 34
reporting an incline measurement of 6 degrees. Controller 30 uses
Equation 1 to calculate an incline force of 1045 lb, and Equation 2
to calculate the draft force to be 1705 lb that accounts for the
incline. In step 204, controller 30 uses Equation 3 to determine
that the differential draft force between pass 2 and 3 is 321 lb.
Because controller 30 calculates this differential draft force of
321 lb is within the acceptable range of the target differential
force of 500 lb, controller 30 has determined that compaction is
complete.
[0054] Controller 30 may make a determination that compaction is
complete for one or more subdivisions of the compaction area,
and/or for the entire compaction area, as described in Step 108
above (Step 206). Controller 30 may display information on display
40a that shows the subdivisions for which controller 30 has
determined that compaction is complete, as described above.
[0055] The examples in the preceding paragraphs illustrate several
aspects of the disclosed compaction detection system The disclosed
apparatus and method may allow compaction determination in a manner
that does not require disruption of the material surface. This may
be beneficial because a disruption of some surfaces, such as the
surface of a roadway, may be undesirable.
[0056] A second aspect of the disclosed compaction detection system
is the measurement of an incline of a surface for use in
determining the amount of compaction of a material. This
measurement may allow compaction determination to be more accurate
by accounting for the draft force that results from the
incline.
[0057] It will be apparent to those skilled in the art that various
modifications and variations can be made to the disclosed
compaction determination system without departing from the scope of
the invention. Other embodiments of the compaction determination
system will be apparent to those skilled in the art from
consideration of the specification and practice of the compaction
determination system disclosed herein. It is intended that the
specification and examples be considered as exemplary only, with a
true scope being indicated by the following claims and their
equivalents.
* * * * *