U.S. patent application number 14/221354 was filed with the patent office on 2014-07-24 for milling machine, in particular surface miner, and method for mining milled material of an open cast surface.
This patent application is currently assigned to Wirtgen GmbH. The applicant listed for this patent is Wirtgen GmbH. Invention is credited to Winfried von Schonebeck, Stefan Wagner.
Application Number | 20140205400 14/221354 |
Document ID | / |
Family ID | 40786500 |
Filed Date | 2014-07-24 |
United States Patent
Application |
20140205400 |
Kind Code |
A1 |
von Schonebeck; Winfried ;
et al. |
July 24, 2014 |
Milling Machine, In Particular Surface Miner, And Method For Mining
Milled Material Of An Open Cast Surface
Abstract
In a method for milling an opencast mining surface or for
milling off layers of an asphalt or concrete traffic surface with a
milling machine removing the ground surface, by milling the ground
surface along a predetermined milling track and by transporting the
milled material via a conveying device to at least one container of
a truck that travels along next to the milling machine, a relative
position between the container and the conveying device is
automatically controlled to regulate the loading of the
container.
Inventors: |
von Schonebeck; Winfried;
(Vettelschoss, DE) ; Wagner; Stefan; (Bad Honnef,
DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Wirtgen GmbH |
Windhagen |
|
DE |
|
|
Assignee: |
Wirtgen GmbH
Windhagen
DE
|
Family ID: |
40786500 |
Appl. No.: |
14/221354 |
Filed: |
March 21, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13965892 |
Aug 13, 2013 |
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14221354 |
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12865041 |
Nov 18, 2010 |
8528988 |
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PCT/EP2009/051383 |
Feb 6, 2009 |
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13965892 |
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Current U.S.
Class: |
414/345 ;
414/809 |
Current CPC
Class: |
B65G 67/22 20130101;
E21C 41/26 20130101; E21C 25/10 20130101; E21C 47/00 20130101; E01C
23/127 20130101; E01C 23/088 20130101; E21C 25/68 20130101 |
Class at
Publication: |
414/345 ;
414/809 |
International
Class: |
B65G 67/22 20060101
B65G067/22; E21C 47/00 20060101 E21C047/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 8, 2008 |
DE |
102008008260.0 |
Claims
1. A method of controlling a loading process of a transport
container of a transport vehicle by a milling device during a
milling operation, wherein the milling device comprises a conveyor,
via which milled material is transported to the transport container
during a milling operation of the milling device, and a control
unit, comprising the steps: a) detecting the relative position of
the transport container in a loading range of the milling device
via a sensor device; b) starting the loading process by starting up
the conveyor; c) monitoring the relative position of the transport
container via the sensor device; and d) issuing a signal when a
predetermined fill level of the transport container is determined,
for stopping the loading process.
2. A method according to claim 1, wherein the control unit controls
driving movement of the transport vehicle during the loading
operation.
3. A method according to claim 1, wherein the control unit
considers at least one of the following operating parameters of the
milling device for controlling the loading process: speed of the
milling device during the milling operation; milling depth of a
milling rotor; and delivery speed of a conveyor belt of the
conveyor.
4. A device for controlling a loading process of a transport
container of a transport vehicle by a milling device during a
milling operation, wherein the milling device comprises a conveyor
via which milled material is transported into the transport
container during a milling operation of the milling device, wherein
the device comprises a sensor device designed for detection of a
relative position of the transport container to the milling device,
and in that the device comprises a control unit, which controls the
loading process based on the relative position of the transport
container to the milling device detected by the sensor device.
5. A milling machine, comprising a device according to claim 4 for
implementing a method according to claim 1.
6. A milling machine according to claim 5, wherein the milling
machine comprises a road milling machine or a device for removal of
soil material.
Description
[0001] The invention relates to a method for milling a ground
surface, as well as to a milling machine.
[0002] In mining, earthwork and rock operations, the mining of
solid earth materials in the form of milled material offers a great
advantage over drilling and blasting as it can be performed with
much greater economic efficiency.
[0003] The milling machine, generally called a surface miner, is
able to crush the mined material to such a small size that it can
be processed without any or requiring only minor subsequent
treatment. The material removed by a milling drum is loaded, via
loading conveyors, onto a truck that travels along next to the
milling machine. In the process, the milled material is cut,
crushed and finally loaded.
[0004] A known method provides that the ground surface of an
opencast mining surface is milled along a predetermined milling
track having a predetermined length. In the process, the milling
operation is optimized, in terms of milling depth and milling
speed, in accordance with the machine's power and the type of
material to be milled.
[0005] The milled material is transported via a conveying device to
at least one container of a truck that travels along next to the
milling machine, said truck having a predetermined maximum loading
volume per load. Once the truck is fully loaded, it is replaced
with an unloaded truck.
[0006] At the end of the milling track, the milling machine turns
so that an adjoining milling track can be removed. It is of
disadvantage in this process that the truck may not be fully loaded
at the end of the milling track so that the vehicle either needs to
transport the milled material away being only partially loaded, or
else needs to wait for the turning manoeuvre to be completed, in
which case the working process will have to be interrupted once
again during the next truck change until changing of the trucks has
been completed. In order to minimize the breaks in operation, it is
also known to use truck and trailer combinations that are provided
with one or several trailers. With such truck and trailer
combinations, there is the problem all the more, however, of the
truck and trailer combination not being fully loaded at the end of
the milling track. As such a truck is not able to perform a turning
manoeuvre, there is the problem all the more in this arrangement of
it not being possible to fully load the truck and trailer
combination.
[0007] A further problem lies in loading the container of a truck
evenly in order to be able to make maximum use of the container
volume.
[0008] It is therefore the object of the present invention to
specify a method for milling an opencast mining surface that can be
performed with greater economic efficiency.
[0009] To this end, the following is provided in accordance with
the method according to the present invention: [0010] calculation
of the maximum total loading volume resulting over the length of
the current milling track as a function of the current effective
working width and a milling depth that has been optimized in
relation to a predetermined, preferably maximum milling power,
[0011] calculation of the number of truck loads required for the
maximum total loading volume of a milling track, [0012]
determination of an effective total loading volume of the current
milling track, which results from the volume of the nearest whole
number of loads, and [0013] adjustment of the adjustable total
milling volume of the milling machine over the length of the
milling track to match the effective total loading volume that
results in a whole number of loads.
[0014] The invention enables the milling operation to be optimized
in such a manner that, at the end of a current milling track, the
container of a truck is, or containers of a truck are, also
completely filled so that journeys of the trucks or truck and
trailer combinations with containers not fully loaded are avoided,
thus also minimizing the number of breaks in operation for the
purpose of changing the trucks.
[0015] At the same time, the advance speed may be increased, for
example, when working at a reduced milling depth so that the time
required for milling off a milling track can be reduced.
[0016] It is preferably provided that the adjustable total milling
volume of the milling machine in a milling track is adjusted to
match a total loading volume which results from the volume of the
nearest lower whole number of loads.
[0017] In this case, adjustment of the total milling volume to
match the specified effective total loading volume is preferably
effected by altering the milling depth. The reason for this is
that, by reducing the milling depth, the total milling volume
within a milling track can be reduced in such a fashion that it
corresponds to the specified effective total loading volume that
enables a whole number of loads to be achieved in a milling
track.
[0018] An alternative possibility consists in adjusting the total
milling volume to match the specified effective total loading
volume by altering the effective working width by selecting a
different overlap of adjoining milling tracks.
[0019] In this case, the milling depth optimized for the milling
process is maintained, and the reduction of the total milling
volume for adjustment to the total loading volume is adjusted by
partly travelling over the previous milling track.
[0020] It is provided in this arrangement that the advance speed of
the milling machine is adjusted to match the effective total
milling volume in such a fashion that a preselected milling power,
preferably maximum milling power, is maintained or achieved.
[0021] In order to improve the effectiveness of the milling process
and the even loading of the container, it may also be provided that
the travel speed of the truck is controlled, as a function of the
advance speed of the milling machine, in such a fashion that the
loading space of the at least one container is loaded evenly and
fully over the length up to the maximum loading volume.
[0022] This is preferably effected by regulating the loading
process by means of controlling the travel speed of the truck as a
function of the advance speed of the milling machine and of the
measured loading condition of a container.
[0023] The travel speed or the current position of the truck may
alternatively be controlled as a function of the advance speed of
the milling machine, or of the distance travelled by the milling
machine in the current milling track, or of the current discharge
position of the transport device.
[0024] It may further be provided that the travel speed or the
current position of the truck is controlled in such a fashion that
the discharge position of the conveying device above the at least
one container moves from a front or rear end position inside the
container to an end position that is opposite in longitudinal
direction.
[0025] The travel speed of the truck is preferably controlled in
such a fashion that the travel speed of the truck is higher than or
equal to the advance speed of the milling machine.
[0026] It may alternatively be provided that the travel speed of
the truck is controlled in such a fashion that the travel speed
shows a constant positive difference to the advance speed of the
milling machine.
[0027] It may alternatively be provided that the travel speed of
the truck is controlled in such a fashion that the travel speed of
the truck is altered in a discontinuous fashion.
[0028] At the beginning of the loading process, it may be provided
that controlling the travel speed of the truck at a higher travel
speed than the advance speed of the milling machine begins only
after a sufficiently high initial fill has been discharged at the
front or rear end position.
[0029] The method can be applied to advantage in particular when
truck and trailer combinations with several trailers connected to
one another in an articulated fashion are used.
[0030] In order to enable a continuous loading process, it is
particularly advantageous in this arrangement if containers on
several trailers connected to one another in an articulated fashion
are used in which the upper end edges of the opposite end walls of
adjacent containers overlap.
[0031] Containers may be used in this arrangement, the opposite end
walls of which are provided with a mutually adapted curvature about
an axis orthogonal to the ground surface in such a fashion that the
opposite end walls have a smallest possible mutual distance but
enable a mutual turning movement of the trailers both laterally and
in a ramp transition area nonetheless.
[0032] Containers may also be used, the front end wall side of
which is curved in a convex manner and is provided, preferably at
the front end edge, with a projecting collar that covers a driver's
cabin of the truck and/or the rear upper concavely curved end edge
of the end wall of a container travelling ahead.
[0033] In the following, one embodiment of the invention is
explained in greater detail with reference to the drawings.
[0034] FIG. 1 a graphic representation of a so-called opencast pit
of an opencast mining surface,
[0035] FIG. 2 loading of a container of a truck via a transport
conveyor of the milling machine,
[0036] FIG. 3 a side view of a surface miner,
[0037] FIG. 4 a top view of a surface miner,
[0038] FIG. 5 a complete cross-section of a pit in the working
direction of the milling machine,
[0039] FIG. 6 a complete cross-section of a pit transverse to the
working direction,
[0040] FIG. 7 definition of the actual cutting depth,
[0041] FIG. 8 material heaps with realistic and idealized loading,
and
[0042] FIG. 9 a basic structure of a truck control unit.
[0043] FIG. 1 shows an opencast pit of an opencast mining surface,
wherein the reference symbol 4 shows the ground surface to be
processed, the area 6 shows a ramp which leads to an elevated
turning area 8 in the respective periphery of the opencast pit. The
surface miner 3 can turn in said turning area 8 after a milling
track has been removed in order to process an adjoining milling
track in the opposite direction.
[0044] An opencast pit has a size of, for example, approx. 100 m in
width and approx. 500 m in length.
[0045] As can be seen from FIG. 2, the milled material removed by
the surface miner 3, such as ore or coal, is loaded via a transport
conveyor 2 onto a truck 1 that may also be provided with one or
several containers 10. A container is located on the truck 1, said
container having a loading volume of, for instance, 100 t. Truck
and trailer combinations with a total number of three containers of
100 t each mounted on trailers are frequently used, so that the
total loading capacity of such a truck load amounts to approx. 300
t. When a truck with a 100-t container is used, changing of the
trucks needs to be performed approx. 16 to 17 times over the length
of a milling track of approx. 500 m. This means that a short break
in operation during changing of the trucks is required after every
30 m already, as the transport conveyor needs to be stopped and,
due to the high milling power of the milling machine, the milling
process thus also needs to be interrupted briefly during changing
of the vehicles.
[0046] FIG. 2 shows a surface miner 3 that is provided with a
control unit 12 for controlling the removal process during the
mining of milled material of an opencast mining surface or during
the milling off of layers of an asphalt or concrete traffic
surface, and for controlling the transporting away of the removed
milled material for loading onto a truck.
[0047] The ground surface is removed along a predetermined milling
track having a predetermined length.
[0048] The milled material is conveyed via a conveying device, for
instance, a transport conveyor 2, to at least one container of a
truck 1 that travels along next to the milling machine, said truck
1 having a predetermined maximum loading volume per load.
[0049] A fully loaded truck is replaced with an unloaded truck when
the maximum loading volume of a truck load has been reached.
[0050] The control unit 12 of the milling machine 3 calculates
[0051] the maximum total loading volume resulting over the length
of the current milling track as a function of the current effective
working width and a milling depth that has been optimized in
relation to a predetermined, preferably maximum milling power,
[0052] the number of truck loads required for the maximum total
loading volume of a milling track, and determines [0053] an
effective total loading volume of the current milling track, which
results from the nearest whole number of loads.
[0054] The control unit 12 then adjusts the adjustable total
milling volume of the milling machine over the length of the
milling track to match the effective total loading volume that
results in a whole number of loads.
[0055] For the purpose of setting and adjusting the total milling
volume, the control unit 12 can calculate the effective total
loading volume which results from the nearest lower whole number of
loads.
[0056] For the purpose of adjusting the adjustable total milling
volume to match the specified effective total loading volume, the
control unit 12 can alter, preferably reduce, the milling
depth.
[0057] For the purpose of adjusting the adjustable total milling
volume to match the specified effective total loading volume, the
control unit 12 can alternatively alter the effective working width
by selecting a different overlap of adjoining milling tracks.
[0058] The control unit 12 can set the advance speed of the milling
machine to a preselected milling power, preferably maximum milling
power.
[0059] In addition, the control unit 12 can control the travel
speed of the truck as a function of the advance speed of the
milling machine in such a fashion that the loading space of the at
least one container is loaded evenly and fully over the length up
to the maximum loading volume.
[0060] The control unit 12 can regulate the loading process of at
least one container by controlling the travel speed of the truck as
a function of the advance speed of the milling machine and of the
measured loading condition of the container.
[0061] The control unit 12 can control the travel speed or the
current position of the truck as a function of the advance speed of
the milling machine, or of the distance travelled by the milling
machine in the current milling track, or of the current discharge
position of the transport device in relation to the truck.
[0062] In this arrangement, the control unit 12 can control the
travel speed or the current position of the truck in such a fashion
that the discharge position of the conveying device above the at
least one container moves from a front or rear end position inside
the container to an end position that is opposite in longitudinal
direction.
[0063] Preferably, the control unit can control the travel speed of
the truck in such a fashion that the travel speed of the truck is
higher than or equal to the advance speed of the milling
machine.
[0064] The control unit 12 can increase the travel speed of the
truck only after a sufficiently high initial fill has been reached
at the front or rear end position.
[0065] The containers may be arranged on several trailers connected
to one another in an articulated fashion, in which case the
adjacent upper end edges of the opposite end walls overlap.
[0066] The adjacent end walls of the containers on the several
trailers connected to one another in an articulated fashion may be
provided with a mutually adapted curvature about an axis orthogonal
to the ground surface in such a fashion that the end walls have a
smallest possible mutual distance but enable a lateral turning
movement of the trailers nonetheless.
[0067] The containers may be curved in a convex manner at the front
end wall side and be provided, preferably at the front end edge,
with a projecting collar that covers a driver's cabin of the truck
and/or the rear upper concavely curved end edge of the end wall of
a container travelling ahead.
[0068] A dimensioning and control concept for automated opencast
mining is described in the following. The procedure comprises the
following steps: calculation/dimensioning of the cutting depth for
each layer (as a function of a "vertical" opencast mining process,
assuming that the pit dimensions are known) to achieve optimal
truck loading for each layer, application of a control concept for
the opencast mining/loading process to achieve optimal truck
loading at minimized control and communication efforts.
[0069] The fundamental advantage of the following control concept
lies in the fact that a continuous loading process between truck
and opencast milling machine, where both machines travel at a
constant speed, is especially easy to realize with regard to the
control concept and requires almost no communication between the
milling machine and the truck (except at the beginning and at the
end of the loading process).
[0070] The principle of the present invention consists in
controlling the truck speed and direction as a function of the
actual position and speed of the milling machine (or of the
position and speed of the conveyor belt of the milling machine
respectively), the cutting depth and cutting width of the milling
machine and other process parameters known in advance, such as the
maximum payload of the truck, the equivalent loading length of the
truck and the density of the milled material.
[0071] Calculation of the Optimal Cutting Depth as a Function of
the Vertically Progressing Layer Mining Process:
[0072] General Definitions and Relations:
[0073] Known Process Parameters and Variables: [0074] l.sub.min
e,max in [m]: maximum total horizontal distance to be mined without
the milling machine turning back (including the ramp and the flat
part; see FIG. 5) [0075] .alpha..sub.ramp in [m]: mining ramp
angle; see FIG. 5 [0076] .rho..sub.mat in [t/ m.sup.3]: density of
the mined material [0077] M.sub.pay in [t]: payload of the truck
[0078] L in [-]: loosening factor, relation between the density of
the cut material and the density of the loaded material [0079]
F.sub.T,max in [m]: maximum cutting depth [0080] F.sub.B in [m]:
cutting width [0081] F.sub.T,act in [m]: actual cutting depth
[0082] Unknown process variables to be determined (in the sequence
of clarification): [0083] l.sub.min e,act in [m]: actual total
horizontal distance to be mined without the milling machine turning
back (including the ramp and the flat part; see FIG. 5) [0084]
L.sub.ramp,act in [m]: actual horizontal distance to be mined while
the milling machine is on the ramp; see FIG. 7 [0085]
l.sub.flat,act in [m]: actual horizontal distance to be mined while
the milling machine is on the flat part of the pit cross-section;
see FIG. 7 [0086] Q.sub.ramp,act in [m.sup.3]: material volume to
be loaded on the ramp [0087] Q.sub.flat,act in [m.sup.3]: material
volume to be loaded on the flat part of the mining track [0088]
A.sub.total,act in [m.sup.3]: total material volume to be loaded in
a single track [0089] M.sub.total,act in [t]: total weight to be
loaded in a single track [0090] n.sub.trucks in [-]: number of
trucks required for the total load of a single track.
[0091] FIG. 1 shows a top view of the sample of a pit, and FIGS. 5
and 6 show the relevant cross-sections. A complete pit
cross-section in the working direction of the milling machine is
depicted in FIG. 5. In FIG. 5, 16 depicts the maximum pit length,
18 depicts the maximum mining length, 21 depicts the maximum mining
depth, and 20 depicts the mining ramp, said mining ramp having a
slope of, for instance, 1:10.about.5.71.degree.. The complete pit
cross-section transverse to the working direction is depicted in
FIG. 6. In FIG. 6, 22 depicts the maximum mining depth, and 24
depicts the mining ramp, said mining ramp having a slope of, for
instance, 1:0.25.about.76.degree.. Let it be assumed that the total
pit dimensions as well as the cross-section are known prior to the
start of the mining process. Determination of the dimensions is
typically performed prior to the start of the mining process by
means of an extensive analysis of drilling samples.
[0092] Calculation Procedure: [0093] Start at the top of the pit by
adjusting l.sub.min e, act to the beginning of the track length and
by adjusting the cutting depth to the maximum cutting depth [0094]
Calculate the number of trucks required by means of the cited
procedure [0095] Reduce the number of trucks required to the next
smaller whole number [0096] Recalculate the cutting depth and the
actual horizontal distance on the flat part l.sub.flat,act [0097]
Set l.sub.flat,act as the starting value for l.sub.min e,act to
calculate the next cutting depth
[0098] The material volume that needs to be loaded on a ramp can be
calculated from
Q ramp , act = 1 2 l ramp , act F T , act F B L . ##EQU00001##
[0099] In a similar fashion, the material volume that needs to be
loaded on the flat part can be derived from
Q.sub.flat,act=l.sub.flat,actF.sub.T,actF.sub.BL.
[0100] The total material that needs to be loaded for the entire
track is simply
Q.sub.total,act=Q.sub.flat,act+2Q.sub.ramp,act.
[0101] Substituting the material volume of the ramp and the flat
part results in
Q total , act = l flat , act F T , act F B L + 2 1 2 l ramp , act F
T , act F B L , ##EQU00002##
which can be further simplified to
Q total , act = ( l flat , act + l ramp , act ) l min e , act F T ,
act F B L ##EQU00003##
[0102] The total weight to be loaded is
M.sub.total,act=Q.sub.total,act.rho..sub.mat
[0103] The number of truck loads required for the total load is
n.sub.trucks=M.sub.total,act/M.sub.pay.
[0104] A recalculation of the required cutting depth can now be
performed quite easily by solving the aforementioned equations for
the cutting depth, which results in
F T , act = Q total , act F B L l min e , act . ##EQU00004##
[0105] The current total horizontal distance of the flat part can
be determined by initially calculating the distance of the ramp
l ramp , act = F T , act tan ( .alpha. ramp ) . ##EQU00005##
[0106] The remaining distance of the flat part l.sub.flat,act can
then be calculated from (FIG. 7)
l.sub.flat,act=l.sub.min e,act-2l.sub.ramp,act.
[0107] The total horizontal distance l.sub.min e, act for
calculation of the next layer equals the last calculated distance
of the flat part
l.sub.min e,act=l.sub.flat,act,
with the exception of the first calculation, where said length
needs to be set to the maximum initial horizontal distance
l.sub.min e,max.
[0108] FIG. 8 shows material heaps 26 with realistic and idealized
loading 28, 30, with 32 depicting the loading length.
[0109] Control law for the truck speed:
[0110] General definitions and relations:
[0111] Known process parameters and variables:
F.sub.T in [m]: cutting depth F.sub.B in [m]: cutting width
.nu..sub.SM in [m/min]: advance speed of the milling machine
M.sub.pay in [t]: payload of the truck L in [-]: loosening factor,
relation between the density of the cut material and the density of
the loaded material .rho..sub.mat in [t/m.sup.3]: density of the
mined material l.sub.lc in [m]: equivalent loading length of the
truck
[0112] Unknown process variables to be determined (in the sequence
of clarification):
t.sub.lc in [min]: truck loading time Q.sub.lc in [m.sup.3]:
material volume for one loading cycle {dot over (q)} in
[m.sup.3/min]: material flow rate from the milling machine
A.sub.tray,cr in [m.sup.2]: loadable cross-sectional area of the
truck tray .nu..sub.Truck in [m/min]: truck speed in forward
direction Where: [min]: minutes [m]: metres [m.sup.3/min]: cubic
metres per minute
[0113] The truck-loading cross-sectional area as a function of the
surface milling machine speed, the cutting depth, the cutting width
and the truck speed can be calculated by using the following simple
assumptions and relations: [0114] The material can be loaded onto
the truck without any angle of repose (see FIG. 8 for
illustration). [0115] The truck 1 and the milling machine 3 travel
at a constant speed. [0116] The truck 1 starts loading at the front
end of the truck tray and travels faster than the milling machine.
[0117] There is no storage of material in the milling machine 3.
[0118] A constant loosening of the cut material takes place, i.e.
the material delivered by the conveying device equals the cut
material, multiplied by the loosening factor.
[0119] The material delivered by the milling machine 3 during a
specific loading time tip can be calculated from
Q.sub.lc=F.sub.TF.sub.B.nu..sub.SMLt.sub.lc={dot over
(q)}t.sub.lc.
[0120] The resulting cross-sectional loading area of the truck tray
can be calculated from
A.sub.tray,cr=Q.sub.lc/l.sub.lc
where l.sub.lc represents an equivalent loading length assuming
that the load deposited on the truck resembles a cuboid.
[0121] By substituting the material volume and the loading length
one obtains
A tray , cr = F T F B L v SM v Truck - v SM , ( 1 )
##EQU00006##
which means that for a given cutting depth, a given cutting width
and a given loosening factor the cross-sectional loading area is a
function of the milling machine speed and the difference of milling
machine speed and truck speed. This relation can be verified quite
easily. Assuming that the truck is stationary (V.sub.truck=0), it
results from the aforementioned relation that
A.sub.tray,cr=F.sub.TF.sub.BL,
which means that the material cross-section to be cut by the
milling machine, multiplied by the loosening factor, needs to be
stored in the truck 1.
[0122] To be able to obtain a particular cross-sectional loading
area of the truck tray, equation (1) produces a control law for
adjusting the truck speed and/or the milling machine speed for a
given cutting depth and cutting width. In practice, the loading
area is subject to a limitation that is due to the maximum payload
of the truck tray. With a given maximum payload of the truck tray,
the maximum material volume that can be loaded during one loading
cycle is defined by
Q.sub.lc,max=M.sub.pay/.rho..sub.mat.
[0123] The maximum material volume can then be translated into a
maximum cross-sectional loading area
A.sub.tray,cr,max=Q.sub.lc,max/l.sub.l/c (2).
[0124] Inserting (2) into (1) and solving (1) for the truck speed
produces a feedforward control law for the truck speed:
v Truck = v SM ( 1 + F T F B L .rho. mat l lc M Pay ) .
##EQU00007##
[0125] The basic structure of a truck control unit is depicted in
FIG. 9. The truck position and speed feedforward control unit 34
includes a feedforward control rule for the truck speed and for
mapping the conveyor position onto the truck position. The truck
position and speed feedforward control unit 34 includes measuring
values 36, such as absolute conveyor positions and speeds, actual
cutting depth and actual milling machine speed. Additional
parameters 38 exist, such as the maximum payload of the truck, the
loosening factor, the material density, the equivalent loading
length of the truck tray, or the cutting width. 40 depicts the
commanded speeds and positions (direction and amplitude), 42
depicts the truck control device, 44 depicts the control commands,
speed commands, 46 depicts the truck, 48 depicts the absolute truck
position, and 50 depicts the ATS/GPS.
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