U.S. patent application number 10/483366 was filed with the patent office on 2004-09-09 for method for controlling a storage roller and a storage roller for storing sheet-type objects.
Invention is credited to Moritz, Wolfgang, Neumann, Ulrich, Robrecht, Michael.
Application Number | 20040173708 10/483366 |
Document ID | / |
Family ID | 7692601 |
Filed Date | 2004-09-09 |
United States Patent
Application |
20040173708 |
Kind Code |
A1 |
Neumann, Ulrich ; et
al. |
September 9, 2004 |
Method for controlling a storage roller and a storage roller for
storing sheet-type objects
Abstract
In a method for controlling a storage roller for storing
sheet-type objects, in particular banknotes, between the wound
layers of a belt-type film, which is spooled to and fro between a
film drum, which is driven by a first motor and comprises a film
reservoir roll, and a winding drum, which is driven by a second
motor and stores the sheet-type objects, the tension of the film is
controlled to a predefined set value.
Inventors: |
Neumann, Ulrich; (Lippstadt,
DE) ; Moritz, Wolfgang; (Paderborn, DE) ;
Robrecht, Michael; (Paderborn, DE) |
Correspondence
Address: |
McCormick Paulding & Huber
CityPlace II
185 Asylum Street
Hartford
CT
06103-4102
US
|
Family ID: |
7692601 |
Appl. No.: |
10/483366 |
Filed: |
January 9, 2004 |
PCT Filed: |
June 20, 2002 |
PCT NO: |
PCT/DE02/02241 |
Current U.S.
Class: |
242/412.3 ;
242/413.1; 242/528 |
Current CPC
Class: |
B65H 2515/116 20130101;
B65H 29/006 20130101; B65H 2515/116 20130101; B65H 2701/1912
20130101; B65H 2220/01 20130101; B65H 2553/212 20130101; B65H
2301/4191 20130101; B65H 18/103 20130101; B65H 23/1806 20130101;
B65H 2553/51 20130101 |
Class at
Publication: |
242/412.3 ;
242/413.1; 242/528 |
International
Class: |
B65H 023/198; B65H
039/14 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 20, 2001 |
DE |
101 35 542.4 |
Claims
1. A method for controlling a storage roller for storing sheet-type
objects, in particular banknotes, between the wound layers of a
belt-type film (22), which is spooled to and fro between a film
drum (12), which is driven by a first motor (46) and comprises a
film reservoir roll (24), and a winding drum (14), which is driven
by a second motor (56) and stores the sheet-type objects (34),
characterized in that the tension of the film (22) is controlled to
a predefined set value.
2. The method as claimed in claim 1, characterized in that the
actual value of the film tension is measured directly.
3. The method as claimed in claim 1, characterized in that the
actual value of the film tension is calculated from the determined
power consumption of the first motor (46) and the current radius
and moment of inertia of the film drum (12).
4. The method as claimed in one of claims 1 to 3, characterized in
that the circumferential speed (v.sub.g) of the winding drum (14)
is controlled to a predefined set value.
5. The method as claimed in claim 4, characterized in that the
rotational speed of the second motor (56) is measured by means of
an encoder (60) and, from this, the actual value of the
circumferential speed (v.sub.g) of the winding drum (14) and its
angular position is calculated.
6. The method as claimed in one of claims 1 to 6, characterized in
that the rotational speed of the film drum (12) is measured.
7. The method as claimed in one of claims 4 to 6, characterized in
that the physically coupled control loops for the film tension (F)
and for the circumferential speed (v.sub.g) of the winding drum
(14) are decoupled by means of a mathematical filter network, and
in that the drive signals for the first and the second motor (46,
56) are calculated on the basis of the determined actual values for
the film tension (F) and the circumferential speed (v.sub.g) of the
winding drum (14), the rotational speed of the film drum (12) and
the predefined system parameters.
8. A storage roller for storing sheet-type objects, in particular
banknotes (34), comprising a film drum (12) that can be driven by a
first motor (46), with a reservoir roll (24) of a belt-type film
(22), a winding drum (14) that can be driven by a second motor
(56), it being possible for the film (22) to be spooled to and fro
between the film drum (12) and the winding drum (14), means (36)
for supplying sheet-type objects (34) between the wound layers of
the film (22) as the same is wound up onto the winding drum (14)
and for dispensing the sheet-type objects (34) as the film (22) is
unwound from the winding drum (14), and a control device (62) for
driving the first and second motor (46, 56), characterized in that
the control device (62) is designed to control the tension of the
film (22) between the two drums (12, 14) to a predefined set
value.
9. The storage roller as claimed in claim 8, characterized in that
the control device (62) is designed to control the circumferential
speed (v.sub.g) of the winding drum (14) to a predefined set
value.
10. The storage roller as claimed in claim 8 or 9, characterized by
a device (64) for measuring the actual value of the film tension
(F).
11. The storage roller as claimed in claim 10, characterized in
that the device for measuring the actual value of the film tension
(F) is a strain gage (64).
12. The storage roller as claimed in claim 8 or 9, characterized by
means for registering the power consumption of the first motor (46)
and means (62) for calculating the actual value of the film tension
(F) from the registered data and the current radius and moment of
inertia of the film drum (12).
13. The storage roller as claimed in one of claims 8 to 12,
characterized in that an encoder (60) is assigned to the second
motor (46).
14. The storage roller as claimed in one of claims 8 to 13,
characterized in that an encoder (58) is assigned to the first
motor (56).
15. The storage roller as claimed in one of claims 8 to 13,
characterized in that a tachometer is assigned to the film drum
(12).
16. The storage roller as claimed in one of claims 9 to 15,
characterized in that the control device (62) contains a
program-controlled computer which is programmed in such a way that
it calculates the function values of the resulting transfer
functions, which correspond to the two control loops decoupled by a
mathematical filter network, from the determined current and the
predefined data and from this determines the drive signals for the
first and the second motor (46, 56).
Description
[0001] The invention relates to a method for controlling a storage
roller for storing sheet-type objects, in particular banknotes,
between the wound layers of a belt-type film, which is spooled to
and fro between a film drum, which is driven by a first motor and
comprises a film reservoir roll, and a winding drum, which is
driven by a second motor and stores the sheet-type objects.
[0002] Storage rollers are frequently used in automatic teller
machines, since they permit the same banknotes to be stored and
dispensed in a straightforward manner. In the case of filling or
storing, the incoming banknotes are wound one after another onto
the winding drum, between the wound layers. The rotational speed of
the winding drum can in this case be adapted, for example on the
basis of the counted banknotes. In the case of removing or
dispensing the banknotes, these are unwound from the winding drum
again on the "last in, first out" principle, the film running onto
the film drum in the process.
[0003] In order that spooling the film to and fro does not lead to
the film running out of a lateral guide that is present, the film
must be kept continually under tension, in order to prevent the
formation of a loop.
[0004] The most uniform tension possible in the film may be
achieved, for example, by a friction brake acting in both
directions. However, friction brakes have the disadvantage that
they exhibit high changes in frictional torque, in particular after
relatively long operating pauses or else as a result of temperature
changes during relatively long operation. In order to compensate
for this, that is to say always to ensure a reliable operating
state, comparatively high frictional torques have to be set which,
in turn, lead to corresponding wear on the entire mechanism, so
that frequent maintenance and readjustment of the frictional torque
is required. In addition, a correspondingly high power loss
occurs.
[0005] The invention is based on the object of specifying a method
of the type mentioned at the beginning in which, while avoiding the
disadvantages mentioned previously, the formation of a loop of the
film can reliably be avoided and power-saving operation of the
storage roller can be ensured.
[0006] According to the invention, this object is achieved by the
tension of the film being controlled to a predefined set value.
[0007] By controlling the film tension or film pulling force to a
predefined low value, for example 10 newtons, a longer lifetime of
the film can be guaranteed. Stretching processes, which are
frequently observed and, in particular, occur at the edges of the
plastic films and lead to cracks at the film edges or, because of
the nonuniform extension of the film, to the film running out of
its track, can be eliminated completely as a result. As a result of
the fact that a low value for the film tension can be predefined
and maintained, drive motors with lower powers can be used, which
reduces the power consumption of the storage roller. The lower
stressing of the film permits a reduction in the film thickness, so
that, given the same overall space for the storage roller, the
latter has a higher storage capacity.
[0008] For the control, the actual value of the film tension must
be registered. This can be carried out by means of a direct
measurement of the film tension, for example by the use of strain
gages. The actual value of the film tension can, however, also be
calculated indirectly from the determined power consumption of the
first motor and the current radius and moment of inertia of the
film drum.
[0009] Storage rollers, as has been explained above, are generally
used in higher-order devices, for example cash handling devices,
such as in automatic cash safes or in money recycling systems. This
means that the storage roller must be able to store and dispense
banknotes at a speed corresponding to the processing speed of the
banknotes in the higher-order device. For this purpose, it is
expedient if the circumferential speed of the winding drum can be
controlled to a predefined set value. By controlling the
circumferential speed, the storage and dispensing speed of the
storage roller can be matched flexibly to changes in the
higher-order system. In addition, by means of such control, the
distances between the sheets or banknotes to be stored can be
reduced to a minimum. This in turn leads to a higher storage
capacity of the storage roller.
[0010] Given the simultaneous control of the circumferential speed
of the winding drum and the film tension by means of driving the
motors for the film drum and the winding drum, a system with
multivariable control is obtained. The torques of both motors act
both on the winding drum speed and on the film tension or pulling
force of the film, in that, firstly, a predefined winding speed is
to be reached, secondly, by means of appropriate driving of both
motors, the drum discharging film is in each case braked slightly
with respect to the drum accepting film, in order to tension the
film between the drums. This means that the torque of the motor of
the film drum also acts on the circumferential speed of the winding
drum via the film tension which is actually to be influenced.
Conversely, although primarily only the circumferential speed of
the winding drum is to be controlled by the torque of the motor of
the latter, a reaction on the film tension is also produced here.
In order to be able to handle such multivariable control in
practice, the physically coupled control loops for the film tension
and the circumferential speed of the winding drum are decoupled by
computation by means of a mathematical filter network, according to
which the drive signals for the first and the second motor can be
calculated on the basis of the determined actual values for the
film tension and the circumferential speed of the winding drum, the
rotational speed of the film drum and the predefined system
parameters.
[0011] The invention relates further to a storage roller for
carrying out the above-described method according to claims 8 to
16.
[0012] Further features and advantages of the invention emerge from
the following description which explains the invention by using an
exemplary embodiment in conjunction with the appended drawings, in
which:
[0013] FIGS. 1-3 each show a schematic illustration of a storage
roller to explain the mode of operation of the same,
[0014] FIG. 4 shows a schematic illustration of the important
elements of the storage roller according to the invention and its
connection to a control device,
[0015] FIG. 5 shows a simplified physical block diagram of the
controlled system of the storage roller illustrated in FIG. 4
without the motors,
[0016] FIG. 6 shows a mathematical block diagram of the storage
roller and
[0017] FIG. 7 shows a mathematical block diagram of the storage
roller with decoupling filter.
[0018] The storage roller illustrated schematically in FIG. 1
comprises a housing 10 in which a film drum designated generally by
12 and a winding drum designated by 14 are mounted such that they
can rotate about mutually parallel axes 16 and 18. The film drum 12
has a drum core 20, onto which a belt-type film 22 consisting of
plastic can be wound up to form a roll 24, the minimum and the
maximum diameters of the film roll 24 being indicated in FIG. 1.
The film 22 runs from the film drum 12 over stationary deflection
rollers 26 and a movable deflection roller 28 to the winding drum
14, where it runs onto a drum core 30 of the winding drum 14 and
forms a storage roll 32. The movable deflection roller 28 is in
this case held, by means not illustrated, in each case on the
[0019] circumference of the winding drum 14. The positions of the
movable deflection roller 28 at minimum radius and maximum radius
of the winding drum 14 are likewise indicated in FIG. 1.
[0020] In order to insert sheet-type objects, for example banknotes
34, into the gap between the circumferential surface of the winding
drum 14 and the movable deflection roller 28, and thus between two
wound layers of the film 22 running onto the winding drum 14, use
is made of a slotted transport guide 36, which is adjustable, just
like the movable deflection roller 28.
[0021] If the film drum 12 and the winding drum 14 are rotated in
the counterclockwise direction according to FIG. 2, so that the
film 22 runs onto the winding drum 14 in the direction indicated by
the arrows in FIG. 2, banknotes 34 are wound into the roll 32, that
is to say stored in the storage roller. If, on the other hand, the
drums 12 and 14 are driven in the clockwise direction in the manner
illustrated in FIG. 3, the film 22 runs from the winding drum 14
onto the film drum 12, the banknotes 34 being dispensed from the
gap between the surface of the winding drum 14 and the movable
deflection roller 28, that is to say being removed from store. The
functioning described to this extent of a storage roller is known
per se.
[0022] FIG. 4 shows the important elements of the storage roller
and its linking with an open-loop and closed-loop control device.
In this case, the elements coinciding with the illustration in
FIGS. 1 to 3 are also provided with the same reference numbers.
[0023] The drum core 20 of the film drum 12 is connected to a shaft
38, which bears a toothed pulley 40. The latter is coupled by a
toothed belt 42 to the drive pinion 44 of an electric motor 46.
[0024] In the same way, the drum core 30 of the winding drum 14 is
connected to a shaft 48 which bears a toothed pulley 50. The latter
is connected via a toothed belt 52 to the drive pinion 54 of a
second electric motor 56.
[0025] Each of the electric motors 46 and 56 is coupled to an
encoder 58 and 60, respectively, for example an incremental
decoder, whose output signal is in each case supplied to a control
device 62. The control device 62 receives a further input signal
from a strain gage 64 which is used to measure the actual value of
the film tension, it being possible for the current film tension
also to be determined in another way, as was explained above.
[0026] On the basis of the rotational speed information determined
by the encoders 58 and 60 and of the actual value of the film
tension, the predefined set values for the film tension and the
circumferential speed of the winding drum 14 and also the
predefined system parameters, the control device 62 then determines
drive signals for the motors 46 and 56 in order to drive the latter
such that the predefined set values for the film tension and the
circumferential speed of the winding drum 14 are maintained.
[0027] The block diagram according to FIG. 5 shows the coupling
between the actuating variables and the controlled variables of the
system. In this case, the formula symbols in FIG. 5 designate the
following variables:
[0028] M.sub.G, M.sub.F=torques of the motors 56, 46
[0029] V.sub.g, V.sub.f=circumferential speeds of the drums 14,
12
[0030] F=film tension
[0031] d, c=damping and spring constants of the film
[0032] J.sub.G, J.sub.F=moments of inertia of the drums 14, 12
[0033] r.sub.G, r.sub.F=actual radii of the drums 14, 12
[0034] The controlled variables are the film tension F and the
circumferential speed vg of the winding drum 14. The actuating
variables are the motor torques M.sub.F and M.sub.G. The torque
M.sub.F of the film drum motor 12 also acts on the speed V.sub.G of
the winding drum via the film tension F which is actually to be
influenced. Primarily, only the circumferential speed V.sub.G of
the winding drum 14 is intended to be controlled by the torque
M.sub.G of the winding drum motor 56. However, a reaction on the
film tension is also produced here, since the latter is certainly
intended to be produced by means of a difference in the
circumferential speeds of the film drum 12 and the winding drum
14.
[0035] The coupling between the actuating and controlled variables
is reproduced by the mathematical block diagram according to FIG.
6. Here, Gi (s) designates the transfer functions which describe
the dynamic behavior of the system. The arrows show the coupling
paths between the actuating variables M.sub.F, M.sub.G and the
controlled variables F, v.sub.g.
[0036] In order to be able to handle such multivariable control in
practice and to determine the required controllers, the coupling
between M.sub.G and F and, respectively, M.sub.F and v.sub.g must
be eliminated. This can be done in a mathematical way by means of a
filter network according to FIG. 7. This filter network comprises
transfer functions V.sub.i (s), which have to be determined such
that the following system of equations is satisfied:
V.sub.1(s).multidot.G.sub.3 (s)=V.sub.3(s).multidot.G.sub.4(s)
V.sub.2(s).multidot.G.sub.1(s)=V.sub.4(s).multidot.G.sub.2(s)
[0037] If the above equations are satisfied, the undesired coupling
paths in the system are eliminated by the filter network connected
upstream, so that only the motor torque M.sub.G is coupled to the
circumferential speed v.sub.g and the motor torque M.sub.F is
coupled to the film tension F. As a result, two control loops are
produced which can be designed independently of each other.
[0038] During the design of the control, in addition to the
above-described coupling of the system variables, it must be noted
that, as a result of the film being wound and unwound, the radii of
the drums and, associated with this, the moments of inertia of the
same change. The radii and moments of inertia changing over time
result in a nonlinear system behavior. The change in the radii can
be described approximately by an Archimedean spiral: 1 r film drum
= r drum core + a 2 ( 0 + )
[0039] Explanation of the formula symbols:
[0040] r.sub.film drum=actual radius of the drum with film
[0041] r.sub.drum core=radius of the drum without film, that is to
say radius of the drum core
[0042] a=thickness of the film
[0043] .phi..sub.0=starting angle of the drum
[0044] .phi.=actual angular position of the drum
[0045] The angular position .phi. of the drums can be determined by
means of measurement and integration of the angular speed of the
motors 46 and 56.
[0046] With the aid of the previously determined radii and the
material characteristics of the film 22, the moment of inertia of
the film is determined: 2 J film = 1 2 film b film ( r film drum 4
- r drum core 4 )
[0047] Explanation of the formula symbols:
[0048] b.sub.film=width of the film
[0049] P.sub.film=density of the film
[0050] The respective film roll 24, 32 is in this case considered
as a hollow cylinder which is plugged onto the respective drum core
20 or 30. The moments of inertia of the drum cores 20, 30 are
constants and are determined from the constructional data.
[0051] In order to take account of the influence of the banknotes
to be stored on the radius and the moment of inertia of the winding
drum 14, a simple model was developed which describes the banknotes
as a "paper layer" between the film layers. In the case of the
paper layer, a density is calculated which takes into account the
distances between the banknotes set by the control.
[0052] Since the rate of change of the radii and therefore of the
moments of inertia at a required maximum winding drum speed v.sub.g
of 1.2 m/s is relatively low, the change over time of the system
parameters can be compensated for by simple linear transfer
functions with changing coefficients.
[0053] For the control of the film tension and the circumferential
speed v.sub.g of the winding drum 14, control concepts known from
the literature, such as cascade control systems or else state
control systems with observer, can be used. Irrespective of the
respective direction of rotation, the motor 56 on the winding drum
14 then adjusts only the desired winding speed v.sub.g. The film
drum motor 56, on the other hand, is responsible only for
maintaining the desired film tension F.
[0054] Instead of an incremental encoder 58 on the film drum motor
46, a simple pulse transmitter or counter can also be used which,
during each full revolution of the film drum 12, is incremented or
decremented, since the moment of inertia of the film drum 12
changes only relatively little during each revolution and since the
determination of the film drum speed is not absolutely necessary
for the control of the entire system.
[0055] In order to measure the film tension, a strain gage 64 is
used in the exemplary embodiment illustrated. However, the actual
value of the film tension can also be determined indirectly by
measuring the current in the motor 46 and by calculating the radius
and the moment of inertia of the film drum 12.
* * * * *