EP1409388B1 - Method for controlling a web accumulator and web accumulator for storing sheetlike objects - Google Patents

Abstract

The invention relates to a method for controlling a storage roller (10) for storing sheet-type objects (34), in particular bank notes, between the wound layers of a belt-type film (36), the latter being wound and unwound between a film drum (12), which is driven by a first motor (16) and comprises a film reservoir roll, and a winding drum (14), which is driven by a second motor (18) and stores the sheet-type objects. According to the invention, the tension of the film is adjusted to a predetermined set value.

Description

The invention relates to a method for controlling a reel storage for storing sheet-like objects, in particular banknotes, between the winding layers of a band-shaped film, between a driven by a first motor, a film supply roll comprising a film drum and a second motor driven, the sheet-shaped objects storing winding drum is spooled back and forth.

Role repositories are often used in ATMs because they allow easy storage and dispensing of the same banknotes. When filling or storing the incoming banknotes are successively wound on the winding drum between the winding layers. The speed of the winding drum can be adapted, for example, depending on the counted banknotes. When the banknotes are being stored or dispensed, they are unwound from the reeling drum according to the "load in, first out" principle, whereby the film accumulates on the film drum.

Thus, the back and forth rewinding of the film does not cause the film runs out of an existing lateral guide, the film must be kept constantly under train to avoid looping.

In WO 94/03384 such a roller storage is described, in which the torque of the film winding motor is always greater than the torque of the film unwinding motor to avoid looping.

A uniform as possible tensile stress in the film can be achieved, for example, by acting in both directions friction brake. But friction brakes have the disadvantage that they high changes in the friction torque, especially after have longer breaks or even by temperature changes during prolonged operation. To compensate for this, ie always to ensure a safe operating condition, comparatively high friction moments must be set, which in turn lead to a corresponding wear on the entire mechanism, so that frequent maintenance and adjustment of the friction torque is required. In addition, a correspondingly high energy loss occurs.

The invention has for its object to provide a method of the type mentioned, in which while avoiding the aforementioned disadvantages, a looping of the film reliably avoided and energy-saving operation of the roller storage can be guaranteed.

According to the invention, this object is achieved in that the actual value of the film tension required for regulating the film tension to a predetermined desired value is calculated indirectly from the determined power consumption of the first motor and the current radius and moment of inertia of the film drum.

By controlling the film tension or film tensile force to a predetermined low value, for example 10 Newton, a longer life of the film can be guaranteed. Frequently observed stretching operations, which occur in particular at the edges of the plastic films and lead to cracks on the film edges or because of the uneven elongation of the film to allow the film to run out of its track, can thereby be completely eliminated. The fact that a low value for the film tension can be specified and maintained, drive motors can be used with lower power, thereby reducing energy consumption of the reel memory is reduced. The lower stress of the film allows a reduction of the film thickness, so that with the same space for the role memory this has a higher storage capacity.

Alternatively, the actual value of the film tension can also be detected by a direct measurement of the film tension, for example by the use of strain gauges.

Role repositories, as discussed above, are typically used in higher-level devices such as cash processing devices, such as cash registers. in automatic cash vaults or in money-recycling systems. This means that the reel store must be able to store and output banknotes at a speed corresponding to the processing speed of the banknotes in the superordinate device. For this purpose, it is expedient if the peripheral speed of the winding drum can be regulated to a predetermined desired value. By controlling the peripheral speed, the storage and output speed of the reel memory can be flexibly adapted to changes in the parent system. In addition, such a rule, the distances between the sheets or banknotes to be stored are reduced to a minimum. This in turn leads to a higher storage capacity of the reel memory.

In the simultaneous control of the peripheral speed of the winding drum and the film tension by controlling the motors for the film drum and the winding drum to obtain a system with a multi-variable control. The Torques of both motors act both on the winding drum speed and on the film tension or tensile force of the film, on the one hand a predetermined winding speed to be achieved, on the other hand by a corresponding control of both motors, the film releasing drum is slightly braked against the film receiving drum to the Tensioning film between the drums. This means that the moment of the motor of the film drum on the actually influencing film tension also acts on the peripheral speed of the winding drum. Conversely, although only the circumferential speed of the latter is to be controlled by the torque of the motor of the winding drum, but here, too, a reaction to the film tension. In order to be able to handle such a multi-variable control practically, the physically coupled control loops for the film tension and the peripheral speed of the winding drum are computationally decoupled by a mathematical filter network, which on the basis of the determined actual values for the film tension and the peripheral speed of the winding drum, the speed of the Film drum and the predetermined system parameters, the drive signals for the first and the second motor can be calculated.

The invention further relates to a roller storage for carrying out the method described above according to claims 5 to 7.

Figuren 1-3

jeweils eine schematische Darstellung eines Rollenspeichers zur Erläuterung der Arbeitsweise desselben,

Figur 4

eine schematische Darstellung der wesentlichen Elemente des erfindungsgemäßen Rollenspeichers und ihre Verbindung mit einer Steuereinrichtung,

Figur 5

ein vereinfachtes physikalisches Blockschaltbild der Regelstrecke des in Figur 4 dargestellten Rollenspeichers ohne die Motoren,

Figur 6

ein mathematisches Blockschaltbild des Rollenspeichers und

Figur 7

ein mathematisches Blockschaltbild des Rollenspeichers mit Entkopplungsfilter.

Further features and advantages of the invention will become apparent from the following description, which explains the invention with reference to an embodiment in conjunction with the accompanying drawings. Show it:

Figures 1-3

each a schematic representation of a roller storage to explain the operation of the same,

FIG. 4

a schematic representation of the essential elements of the roller storage according to the invention and their connection to a control device,

FIG. 5

a simplified physical block diagram of the controlled system of the role memory shown in Figure 4 without the motors,

FIG. 6

a mathematical block diagram of the role storage and

FIG. 7

a mathematical block diagram of the role repository with decoupling filter.

The roller store shown schematically in Fig. 1 comprises a housing 10 in which a generally designated 12 film drum and a winding drum designated 14 are mounted rotatably about mutually parallel axes 16 and 18 respectively. The film drum 12 has a drum core 20, on which a band-shaped, consisting of plastic film 22 can be wound into a winding 24, wherein in Fig. 1, the minimum and the maximum diameter of the film roll 24 are indicated. The film 22 extends from the film drum 12 via 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 guide roller 28 is thereby not shown by means on the circumference held the winding drum 14. The positions of the movable guide roller 28 with a minimum radius and maximum radius of the winding drum 14 are also indicated in FIG. 1.

For introducing sheet-like objects, such as banknotes 34 in the gap between the peripheral surface of the winding drum 14 and the movable guide roller 28, and thus between two winding layers of the accumulating on the winding drum 14 film 22 is a transport gate 36 which, like the movable guide roller 28 adjustable is.

When the film drum 12 and the winding drum 14 are rotated counterclockwise as shown in Fig. 2 so that the film 22 runs on the winding drum 14 in the direction indicated by the arrows in Fig. 2, banknotes 34 are wrapped in the reel 32, i. stored in the roll storage. In contrast, when the drum 12 and 14 driven in the manner shown in FIG. 3 in a clockwise direction, the film 22 runs from the winding drum 14 on the film drum 12, wherein the banknotes 34 from the gap between the surface of the winding drum 14 and the movable Guide pulley 28 issued, ie be stored out. The operation of a roller store described so far is known per se.

Fig. 4 shows the essential elements of the reel memory and their connection to a control and regulating device. The elements corresponding to the representation in FIGS. 1 to 3 are also provided with the same reference numerals.

The drum core 20 of the film drum 12 is connected to a shaft 38 which carries a belt gear 40. This is coupled via a toothed belt 42 with the drive pinion 44 of an electric motor 46.

Similarly, the drum core 30 of the winding drum 14 is connected to a shaft 48 which carries a belt gear 50. This is connected via a toothed belt 52 with the drive pinion 54 of a second electric motor 56.

Each of the electric motors 46 and 56 is connected to an encoder 58 or 60, e.g. an incremental encoder coupled, the output signal of each of which is supplied to a control device 62. The control device 62 receives a further input signal from a strain gauge 64, which serves to measure the actual value of the film tension, wherein the actual film tension can also be determined by other means, as explained above.

On the basis of the speed information determined by the encoders 58 and 60 and the actual value of the film tension, the predetermined set values for the film tension and the peripheral speed of the winding drum 14 and the predetermined system parameters, the control device 62 then determines activation signals for the motors 46 and 56 to drive them so that the predetermined target values for the film tension and the peripheral speed of the winding drum 14 are met.

M_G, M_F

= Momente der Motoren 56, 46

v_g, v_f

= Umfangsgeschwindigkeiten der Trommeln 14, 12

F

= Folienspannung

d, c

= Dämpfung und Federkonstante der Folie

J_G, J_F

= Trägheitsmomente der Trommeln 14, 12

r_G, r_F

= aktuelle Radien der Trommeln 14, 12

The block diagram of FIG. 5 shows the coupling between the manipulated variables and the controlled variables of the system. The symbols in FIG. 5 denote the following quantities:

M _G , M _F

= Moments of motors 56, 46

v _g , v _f

= Peripheral speeds of the drums 14, 12th

F

= Foil tension

d, c

= Damping and spring constant of the film

J _G , J _F

= Moment of inertia of the drums 14, 12

r _G , r _F

= current radii of the drums 14, 12

The controlled variables are the film tension F and the peripheral speed v _{g of} the winding drum 14. The manipulated variables are the motor torques M _F and M _G. The torque M _{F of} the film drum motor 12 acts on the actual film tension F to be influenced on the speed v _{G of} the winding drum. By the torque M _{G of} the winding drum motor 56, primarily only the peripheral speed v _{G of} the winding drum 14 is to be regulated. But even here there is a retroactive effect on the film tension, since this is to be generated by a difference in the peripheral speeds of the film drum 12 and the winding drum 14.

The coupling between the manipulated and controlled variables is represented by the mathematical block diagram of FIG. Where G _i (s) denotes the transfer functions that describe the dynamic behavior of the system. The arrows show the coupling paths between the manipulated variables M _F , M _G and the controlled variables F, v _g .

$${\mathrm{V}}_2\mathrm{\hspace{1em}}\left(\mathrm{s}\right)\cdot {\mathrm{G}}_1\mathrm{\hspace{1em}}\left(\mathrm{s}\right)={\mathrm{V}}_4\mathrm{\hspace{1em}}\left(\mathrm{s}\right)\cdot {\mathrm{G}}_2\mathrm{\hspace{1em}}\left(\mathrm{s}\right)$$

In order to handle such a multi-variable control practically and to be able to determine the required regulators, the coupling between M _G and F or M _F and v _{g must be} eliminated. This can be done mathematically by a filtering network according to FIG. 7. This filtering network includes transfer functions V _i (s) to be determined such that the following equation system is satisfied: $${\mathrm{V}}_1\mathrm{}\left(\mathrm{s}\right)\cdot {\mathrm{G}}_3\mathrm{}\left(\mathrm{s}\right)={\mathrm{V}}_3\mathrm{}\left(\mathrm{s}\right)\cdot {\mathrm{G}}_4\mathrm{}\left(\mathrm{s}\right)$$

$${\mathrm{V}}_2\mathrm{}\left(\mathrm{s}\right)\cdot {\mathrm{G}}_1\mathrm{}\left(\mathrm{s}\right)={\mathrm{V}}_4\mathrm{}\left(\mathrm{s}\right)\cdot {\mathrm{G}}_2\mathrm{}\left(\mathrm{s}\right)$$

If the above equations are met, the unwanted coupling paths are eliminated in the system by the upstream filter network, so that only the engine torque M _G with the peripheral speed and v _g coupled the engine torque M _F with the film tension F. As a result, two control loops have arisen, which can be designed independently of each other.

When designing the scheme, in addition to the previously described coupling of the system sizes, it should be noted that the radii of the drums and, associated therewith, the moments of inertia of the same change as a result of the winding and unwinding of the foil. The time-varying radii and moments of inertia result in a non-linear system behavior. The change of the radii can be described approximately by an Archimedean spiral: $${\mathit{F}}_{\mathit{film\; drum}}\mathit{=}{\mathit{r}}_{\mathit{Core\; drum}}\mathit{+}\frac{\mathit{a}}{\mathrm{2}\mathit{\pi }}\mathit{(}{\mathit{\phi }}_{\mathrm{0}}\mathit{+}\mathit{\phi }\mathit{)}$$

Explanation of the formula symbols:

r _{film drum}

= current radius of the drum with foil

r _{drum core}

= Radius of the drum without foil, i. Radius of the drum core

a

= Thickness of the film

φ ₀

= Starting angle of the drum

φ

= current angular position of the drum

The angular position φ of the drums can be determined by measuring and integrating the angular velocity of the motors 46 and 56.

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: $${\mathit{J}}_{\mathit{foil}}\mathit{=}\frac{\mathrm{1}}{\mathrm{2}}{\mathit{\rho }}_{\mathit{foil}}{\mathit{b}}_{\mathit{foil}}\mathit{\pi }\mathit{(}{\mathit{r}}_{\mathit{film\; drum}}^{\mathrm{4}}\mathit{-}{\mathit{r}}_{\mathit{Core\; drum}}^{\mathrm{4}}\mathit{)}$$

Explanation of the formula symbols:

b _foil

= Width of the film

ρ _film

= Density of the film

The respective film winding 24, 32 is considered as a hollow cylinder, which is inserted on the respective drum core 20 and 30 respectively. The moments of inertia of the drum cores 20, 30 are constants and are determined from the design data.

In order to take into account the influence of the banknotes to be stored on the radius and the moment of inertia of the winding drum 14, a simple model has been developed which describes the banknotes as a "paper layer" between the film layers. For the paper layer, a density is calculated which takes into account the intervals between the banknotes set by the regulation.

Since the rate of change of the radii and thus the moments of inertia at a required maximum winding drum speed v _g of 1.2m / s is relatively small, the temporal change of the line parameters can be compensated by simple linear transfer functions with changing coefficients.

For the control of the film tension and the peripheral speed v _{g of} the winding drum 14, known from the literature control concepts, such as cascade controls or state controls can be used with observers. Regardless of the respective direction of rotation, the motor 56 then sets only the desired winding speed v _g on the winding drum 14. By contrast, the film drum motor 56 is solely responsible for maintaining the desired film tension F.

Instead of an incremental encoder 58 on the film drum motor 46, a simple pulse generator or counter can also be used, which is incremented or decremented with each full revolution of the film drum 12, since the moment of inertia of the film drum 12 changes relatively little with each revolution and there for the control the total system, the determination of the film drum speed is not absolutely necessary.

To measure the film tension is used in the illustrated embodiment, a strain gauge 64. The actual value of the film tension can also be determined indirectly by the measurement of the current in the motor 46 and by calculating the radius and the moment of inertia of the film drum 12.

Claims (7)

1. Method for controlling a storage roller for storing sheet-type objects, in particular banknotes (34), 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), and the film tension (F) of the film (22) is controlled to a predefined set value, characterized in that the actual value of the film tension (F) of the film (22) 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).
2. Method according to Claim 1, 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_g) of the winding drum (14) and its angular position is calculated.
3. Method according to Claim 1 or 2, characterized in that the rotational speed of the film drum (12) is measured.
4. Method according to one of Claims 1 to 3, characterized in that the physically coupled control loops for the film tension (F) and for the circumferential speed (v_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_g) of the winding drum (14), the rotational speed of the film drum (12) and the predefined system parameters.
5. 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), the control device (62) being designed to control the film tension (F) of the film (22) between the two drums (12, 14) to a predefined set value, 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).
6. Storage roller according to Claim 5, characterized in that an encoder (58) is assigned to the first motor (46) and an encoder (60) is assigned to the second motor (56).
7. Storage roller according to Claim 5 or 6, 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).

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