WO2011042115A1

WO2011042115A1 - Method for modeling a side register control circuit for a processing machine

Info

Publication number: WO2011042115A1
Application number: PCT/EP2010/005676
Authority: WO
Inventors: Stephan Schultze; Holger Schnabel
Original assignee: Robert Bosch Gmbh
Priority date: 2009-10-10
Filing date: 2010-09-16
Publication date: 2011-04-14
Also published as: DE102009048951A1; EP2486458A1

Abstract

The invention relates to a method for modeling a control circuit (300) for controlling a side register of a processing machine for processing a fabric web (101), in particular a printing machine (100) without shafts, wherein at least one machine parameter (v, a), which influences the section reinforcement (Ks), is taken into consideration during modeling.

Description

Method for modifying a page register loop for a

processing machine

description

The present invention relates to a method for modeling a control loop for controlling a side register of a processing machine and a correspondingly arranged arithmetic unit.

Although reference will be made hereafter mainly to printing presses, the invention is not limited thereto but rather to all types of printing presses

Directed processing machines in which a web or sporadic material (sheet) is processed. However, the invention is particularly applicable to printing machines, e.g. Newspaper printing machines, commercial printing machines, gravure printing machines,

Packaging printing machines or securities printing machines, as well as

Processing machines, such as Pouch machines, envelope machines or packaging machines, can be used. The material can be made of paper, cloth, cardboard, plastic, metal, rubber, in foil form, etc.

State of the art

For multi-color printing, printing machines having a plurality of printing units are known, for example, from US Pat. No. 4,932,320, which includes peripheral and side register adjusting devices are provided for register adjustment. In this way, the position of the individual printed color separations can be corrected to each other. In printing machines longitudinal and / or page registers are regulated in order to achieve an optimal printing result. Known controllers, such as P controllers, D controllers, I controllers, etc., as well as any combinations thereof include controller parameters that must be set. Conventional controller parameters are the proportional gain Kp, the integral gain Ki, the differential gain K _D , the reset time T _N , the lead time Tv, delays T, etc. The controller parameters are manually set or evaluated in the prior art via an evaluation of a step response, which is why the machine operator possess control technical knowledge and must adjust the parameters individually.

If the type of controlled system and its route parameters are known, a calculated parameterization is possible in addition to the manual parameterization. For this purpose, it is necessary to model the observed control loop. The control loop structure consists at least of the two elements controller and controlled system (behavior behavior). The path behavior of an actuating movement, for example of a printing unit, is usually modeled as a PT1 element with a path gain Ks and a (speed-dependent) path time constant Ti or Ts. In terms of control technology, the path behavior is usually compensated with the aid of a PI controller in such a way that a system of second order results. There are different design criteria for the P-gain and the I-share. Use then known adjustment methods such. Symmetrical optimum or root locus method.

With regard to the side register control, the known methods have the disadvantage that, on the one hand, the controller parameters have to be entered manually, which usually does not lead to an optimal regulation, and on the other hand the Methods for automatic adaptation are not yet mature enough for optimal results to be achieved.

The unpublished DE 10 2008 035 639, to which reference is expressly made for further details, describes an improved modeling of a register loop in which dead times of the system are taken into account.

DISCLOSURE OF THE INVENTION Against this background, the present invention proposes a method for modeling a control loop for a processing machine and a computing unit having the features of the independent patent claims. Advantageous developments are the subject of the dependent claims and the following description.

Advantages of the invention

The invention is based essentially on the recognition that in the case of a side register control special machine or process parameters have a strong influence on the control by influencing the system gain. By taking into account these parameters in the modeling of the control loop, an improved side register control can be achieved. The control loop modeled in this way can be used to automatically determine the controller parameters, in particular by means of known methods. The controller parameters are thus optimally matched to the underlying processing machine and manual input by a user can be omitted. This excludes a significant source of error in machine setup. In an exemplary determination of the controller parameters, the system gain enters the denominator. For example, the controller gain K _R for a PI controller is calculated at a PT1 distance (see FIG. Optimum to:

κ _, τ _Ν -τ _λ

* SK _S - T 2 - K _s - T _z

where Ks is the path gain, Ti is the path time constant (= Ts) and Ts is the sum time constant. Thus, in the calculation of the controller parameters results in a larger controller gain at a smaller loop gain. In the modeling of the control loop, according to the invention, at least one machine or process parameter influencing the system gain is now also taken into account. Thus, the control loop dynamics of the system can be significantly increased and the control can be optimized.

In the side register control, the deviation of the printed color separations from each other perpendicular to the direction of material flow is usually determined by measuring the register marks in the material flow direction. Thus, the shape of the register mark influences the ratio between the actual lateral deviation and the detected length deviation (see Figure 2). If the register mark shape is taken into account, for example, in the form of the angle of a triangular mark, the control quality can be improved.

In the side register control, the processing material is moved relative to the processing unit, for example a printing cylinder, perpendicular to the material flow direction. The type of movement is dependent on the drive driving this movement, eg spindle drive, stepping motor and the like, and is often characterized by a fixed speed of movement (adjustment speed), at least after setting up. In an advantageous embodiment of the invention, this adjustment speed is taken into account. It has been recognized that the adjustment speed of a Seitenregister- adjustment device directly affect the track gain Ks and thus takes on the controller parameters. It is Ks ~ Verstellgeschwindigkeit. Expediently, the adjustment speed, which also includes, for example, an adjustment rotational speed of the drive together with a feed constant (spindle pitch) of the mechanism, can be input into the arithmetic unit according to the invention and / or can be read out from the relevant drive and / or predefined in the relevant drive.

In the side register control actuators are often used that perform a certain minimum adjustment, for example, because they are pulse-controlled. A maximum adjustment movement per adjustment can, for example, be provided in order not to damage or destroy the material. Advantageously, a minimum adjustment and / or a maximum adjustment of a side register adjustment device are taken into account in the modeling. Thus, the scheme can be improved and the substrate and the machine can be protected from damage. An uneven web run is avoided. A minimum adjustment can be provided as a dead zone in the controller output and / or at the controller input. A maximum adjustment can be provided as a limit in the controller output and / or at the controller input. Expediently, at least one dead time is taken into account in the modeling. Constant, ie not transport speed-dependent and / or speed-dependent dead times are taken into account in order to achieve good results in all speed ranges. For example, a speed-dependent dead time usually has a large influence at low speeds, which decreases with increasing transport speed. However, especially in this speed range, the influence of constant dead times has a particularly disturbing effect since, by definition, they show no speed dependency and can therefore dominate the track behavior in these speed ranges. For further details regarding the Considering dead times, reference is made to the already mentioned DE 10 2008 035 639, which is made part of this application.

Expediently, a determination of controller parameters is carried out on the basis of the modeled control loop. In particular, this determination can be carried out automatically within a computing unit, such as e.g. a controller or a register controller done. With this preferred embodiment of the invention, it is thus possible to automatically provide optimal parameterization of the controller at any time of processing by a processing machine.

Alternatively, it is advisable to carry out the determination of the controller parameters as a function of a characteristic field. As already explained above, only a few variables are used as parameters in the modeling, whereas many variables, such as e.g. the brand shape, adjustment speeds, distances, constant dead times, etc., are fixed. For this reason, it makes sense to use characteristic fields as a function of variable variables, such as, for example, Provide web speed that can be stored, for example, in a memory device of the arithmetic unit. In this way the automatic parameterization of the controllers can be significantly accelerated.

An arithmetic unit according to the invention is, in particular programmatically, configured to perform a method according to the invention.

The implementation of the invention in the form of software is also advantageous, since this allows particularly low costs, in particular if an executing arithmetic unit is still used for further tasks and therefore exists anyway. Suitable data carriers for providing the computer program are in particular floppy disks, hard disks, flash Memory, EEPROMs, CD-ROMs, DVDs Also a download of a program over computer networks (Internet, Intranet etc.) is possible.

Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawings.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination indicated, but also in other combinations or in isolation, without departing from the scope of the present invention.

The invention is illustrated schematically by means of exemplary embodiments in the drawing and will be described in detail below with reference to the drawing.

figure description

Figure 1 shows a schematic representation of a trained as a printing press

Processing machine for which the method according to the invention is suitable,

Figure 2 shows the principle of taking into account a register mark shape in a

Page register control and

Figure 3 shows a schematic representation of a modeled according to the invention

Control circuit for a processing machine in a simplified representation.

In FIG. 1, a processing machine configured as a printing press is designated by 100 as a whole. A printing material, such as paper 101, is formed by printing units 1 10, 120, 130, 140 Bearbeitungsseinrichrungen in the direction R. guided and printed. The printing units are shaftless driven and equipped with drives 1 1 1. The printing units are cylindrical or angle correctable for longitudinal register control, which is indicated by the curved arrows on the drives 1 1 1. The printing units are additionally equipped with side register adjustment devices 12. The Seitenregister- adjusting devices 112 are perpendicular to the material transport direction R at an adjustment speed v adjustable.

The drives 111 and adjusting devices 112 of the individual printing units are connected to a controller 150 via a data connection 151. Furthermore, there are a plurality of sensors 132, 133, 134 for detecting register marks for the control of the side register (optionally longitudinal register), which are also connected to the controller 150 between the printing units. For clarity, only one sensor 134 is shown connected to the controller. In particular, the controller 150 comprises an embodiment of a computing unit according to the invention and is set up for automatic controller parameterization.

In the following it will be described how in the illustrated printing machine in the prior art, a side register control is performed as a color control. In the individual web sections between the printing units 120 to 140 and behind printing unit 140, the sensors 132, 133, 134 are arranged, which determine the register position of the web 101 and, for example, are designed as a brand reader. During the passage of the material web 101, for example paper, the extent of the mark applied by the associated printing unit as well as the mark applied by the first printing unit 110 in direction R are detected by a brand reader (color control of the colors). The measured values are fed to a device for register control (register controller). From this, a respective register deviation can be calculated. Detected register deviations are used to position the respective printing unit. The color control has the advantage that in principle one sensor (behind the last printing unit) is sufficient. However, it takes on the Stand color control correspondingly long, until a printed by the first printing unit print mark is transported to the last printing unit. Only then can the page register control of the last printing unit begin to start its control process. For gravure printing machines, this length can be in the range of 100 m.

According to the illustrated embodiment, the register controller is automatically parameterized using a method according to the invention. It is understood that the register controller may be embodied in the computing unit 150, for example a computer.

In Figure 2, the principle of considering the brand shape is exemplified. With reference to Figure 1, and by way of example using a color control, register mark sensor 134 measures a mark 201 applied by printing unit 110 and a mark 202 applied by printing unit 140. Marks 201 and 202 in the present example are rectangular triangles, for further consideration only the angle a is considered. In the register control, the extent dl of the mark 201 and the extent d2 of the mark 202 in the material flow direction are determined and their difference dl - d2 used for the side register control. The purpose of the side register control is to regulate the difference dl - d2 to 0 (optionally to a specified reference value, since the markers can be measured with a different width due to their contrast). However, as can be seen in the consideration of Figure 2, the difference dl - d2 does not correspond to the actual page register deviation e. The actual deviation e results in the present example of a triangle mark to e = [cos a / sin a] (d2 - dl).

According to the invention, this difference between the control variable d1-d2 used for the control and the actual register deviation e was recognized and taken into account. The difference is from a machine parameter, here from the Brand shape, influences and affects the track gain, in the present example with the factor cos a / sin a.

As a rule, the control deviation d1-d2 is determined in mm (optionally also in degrees) and from this a manipulated variable for the corresponding side register adjusting device 112 is determined. This manipulated variable depends on the adjustment speed v of the adjusting device. If, for example, it is to be adjusted by 1 mm, an adjustment device with an adjustment speed of 1 mm / s requires at least one second, whereas an adjustment device with an adjustment speed of 0.5 mm / s requires at least two seconds for this. In the first case, the system gain is thus greater and thus a smaller controller gain K _R better.

Furthermore, the side register adjusting devices 112 are often designed such that they can only perform a certain minimum adjustment, for example because they are pulse-controlled. In certain situations, this can lead to constant positioning movements, which lead to a troubled web run. For example, assume that an adjustment device can adjust at least x mm per pulse. In a simplifying assumption, a P controller with gain K = 1 is used and the adjustment is fully effective until the next measurement (stretching gain Ks = 1). If a deviation of + x / 2 mm occurs, an adjustment of -x mm occurs. This leads to a deviation of -x / 2 mm. Now it is again adjusted by + x mm, which leads to a deviation of + x / 2 mm. As a result, a constant adjustment is performed. This leads to a troubled system and can swing up at several coupled controllers in the machine. Furthermore, the adjustment can be worn by constant adjustments. Preferably, these minimum adjustments are therefore taken into account in the controller design. The consideration of the minimum adjustment can be provided by a dead zone at the controller output and / or at the controller input. For a pulse-controlled adjustment device, this dead zone at the controller output can be calculated as follows:

(1) dead zone at the controller output = minimum pulse duration * adjustment speed v of the adjustment device.

(2) Dead zone at the controller input = dead zone at the controller output / gain of the controller.

In (2) only the gain of the controller was considered. With a PI controller, the I component of the controller would also have to be taken into account. By using the dead zone, a constantly oscillating adjustment of the adjustment can be prevented. If the dead zone is located at the controller input, then in an embodiment of the invention, this is dynamically adapted as a function of process variables. For example, depending on the speed, a changing P gain of the controller and thus another dead zone at the controller input will result.

In FIG. 3, a control loop modeled according to the invention is shown schematically and designated as a whole by 300. The control circuit may for example be based on a printing press according to FIG. The control loop 300 comprises a PI element 310 with a control gain K _R and a reset time T _N - The path behavior with the path time constant Ts and the path gain Ks is modeled in a PT1 element 340. Existing dead times, such as a constant dead time, which is caused by the computing time of the arithmetic unit, a speed-dependent dead time, which is caused by the ramp behavior of the manipulated variable, a speed-dependent dead time, which is caused by the distance of the sensor from the printing unit, one by the measuring time of Sensor caused constant dead time and / or caused by the data transmission constant dead time, are summarized in a control loop member 330, which is characterized by a sum dead time Ts. The control loop member 330 can be approximated by means of PTI behavior. It goes without saying that other rules-related approximations are also possible. The position of the control loop element 330 within the control loop 300 can be selected by the person skilled in the art. For example, the control loop member 330 may also be disposed in the feedback.

According to a preferred embodiment of the invention, an adjustment speed v of the side register adjustment devices 112 and an angle a of the register marks enter the model of the controlled system 340.

Claims

Claims 1. A method for modeling a control loop (300) for controlling a

Side register (s) of a processing machine for processing a web (101), in particular shaftless printing press (100),

wherein at least one machine parameter (v, a) which influences the path gain (Ks) is taken into account in the modeling.

2. The method of claim 1, wherein the brand form is (a) a

Page register mark (201, 202) is considered as a machine parameter in the modeling.

3. The method of claim 2, wherein at least one angle (a) of an angular, in particular triangular, side register mark (201, 202) is taken into account as machine parameters in the modeling.

4. The method according to any one of the preceding claims, wherein a

Adjustment speed (v) of a page register adjustment device (112) as

Machine parameter is taken into account in the modeling.

5. The method according to any one of the preceding claims, wherein a

Minimal adjustment of a side register adjustment device (112) is taken into account in the modeling.

6.. Method according to one of the preceding claims, wherein a

Maximum adjustment of a side register adjustment device (112) is taken into account in the modeling.

7. The method according to any one of the preceding claims, wherein at least one dead time (Ts) is taken into account in the modeling.

8. The method according to any one of the preceding claims, wherein on the basis of the modeled control loop (300) a determination of controller parameters (K _R , T _N ) takes place.

9. The method of claim 8, wherein the interpretation of the controller parameters (K _R , T _N ) takes place on interference behavior out.

10. The method of claim 8 or 9, wherein the leadership behavior is optimized by pre-filtering the reference variable, in particular by means of a PTI filter.

11. The method of claim 8, 9 or 10, wherein the determination of

Controller parameter (K _R , T _N ) in response to a characteristic field is carried out.

12. The method according to any one of the preceding claims, wherein the

Processing machine is a printing machine (100), in particular a gravure printing machine or a flexographic printing machine.

13. A computing unit (150) adapted to perform a method according to any one of the preceding claims.