EP1883597B1 - Mechanism for controlling a thread displacement, in particular for a textile machine work station - Google Patents

Abstract

The invention relates to a mechanism for controlling a thread displacement, in particular for a textile machine working station comprising a thread guide and an electric motor individual drive provided therefor and an angle sensor for determining an actual angular position (11) (f_real) of a thread guide and a controller (4) for predefining at least one correcting variable (9) (u) for the output stage of the electric motor individual drive for driving the thread. The inventive mechanism for controlling a thread displacement makes it possible to obtain high displacing frequencies by preventing displacement errors, wherein the controller (4) comprises a multivariable control system for accurately controlling at least one correcting variable (9) (u), and thereby the actual angular position (11) (f_real) of the thread guide. A status monitor (12) for accurately determining the internal conditions such as in a real control section (10) and for transmitting them to the controller is provided.

Description

The invention relates to a yarn laying drive, in particular for a workstation of a textile machine, according to the preamble of patent claim 1.

To produce a textile spool, it is for example from the document DE 198 58 548 A1 known, on the one hand, to set the respective textile bobbin in rotation and, on the other hand, to traverse the thread running on the bobbin along the bobbin axis. The traversing of the thread is done for example with the help of a Fingerfadenführers, which is also called wiper. So that a special or predetermined winding structure can be produced in the coil to be produced, the drive of the coil must be separated from the drive of the thread guide. This decoupling of the required drives can also produce precision or stepped precision windings. Thus, this technical measure ensures that winding images are avoided on the coil, which can lead to significant problems during subsequent unwinding. Such textile coils with a so-called Kreuzbewicklung are characterized not only by a relatively stable bobbin, but also by a good flow behavior.

By using one from the publication DE 198 58 548 A1 known thread guide, which is provided with an electromagnetic drive, a high-quality Kreuzbewicklung a textile spool can be created by a relatively fast and accurate traversing of the thread. The use of the finger-like yarn guide allows - from pure mechanical view - thread laying frequencies of more than 30 Hz. However, since high acceleration values act on the reversal points of the thread guide and the mass inertia of the thread guide easily causes overshooting at the reversal points, the drive of the thread guide must be precisely controlled or regulated To avoid thread misalignment. Known from the prior art controls and regulations are only able to achieve a precise drive of the thread guide at lower Fadenverlegefrequenzen. Consequently, the technical possibilities of the yarn guide can only be utilized to a limited extent, which has an overall effect on the winding speeds of the corresponding workstation and thus also on the productivity of the textile machine.

In the non-prepublished publication DE 103 54 587 A1 a special angle encoder for the already described thread guide or wiper is described. Through this angle sensor, which consists inter alia of an analog Hall sensor and a magnet, the actual angular position of the thread guide is detected and passed to an unspecified control or regulation of the thread guide drive for further processing. Although the actual angular position of the thread guide can be determined quickly and precisely by the disclosed angle encoder, this does not solve the previously mentioned problem of the previously used controllers or controls.

The WO 99/05055 A describes a method and a traversing device for laying a thread. Here, the traversing yarn guide is moved by means of an electric motor, wherein the desired position of the traversing yarn guide is determined by a position of the electric motor. The actual position of the traversing yarn guide is by means of a measuring device recorded continuously and fed to a control device which performs a nominal-actual comparison of the position of the traversing yarn guide and generates a corresponding difference signal for controlling the electric motor. The electric motor is amplitude controlled adjustable. In the case of a deviation between the actual position and the nominal position, the electric motor receives a current whose amplitude changes as a result of the difference signal. Thus, the positioning of the traversing yarn guide, in particular in the reverse region with great accuracy feasible.

Based on the aforementioned prior art, it is therefore an object of the present invention to provide a yarn laying drive with a yarn guide that allows high laying frequencies while avoiding thread laying errors. It should be exploited as possible, the existing technical structure or structure.

To solve this problem, a thread laying drive with the features of claim 1 is proposed.

Advantageous developments of the thread laying drive according to the invention are listed in the dependent claims 2 to 8.

On the basis of the predetermined winding structure, the necessary laying curve for the yarn guide, consisting of the respective angular positions, can be calculated. This laying curve must follow the thread guide exactly. According to the invention, for this purpose, the controller comprises a multi-variable control in order to precisely regulate the angular position (φ_ist) of the yarn guide by means of the at least one manipulated variable (u) for the real controlled system. The output stage and the electromechanical laying drive of the thread guide form the real or actual controlled system. By using a multi-variable control thus the desired, precise control can be achieved for positioning the yarn guide at the required Fadenverlegefrequenzen.

The object of the invention is advantageously set up for generating at least one non-measured input variable in addition to the at least one measured input variable of the controller. In order to provide further input variables for the multivariable control of the controller, it is provided that in addition to the predetermined angular position (φ_soll) of the thread guide also several input variables such as the corresponding moment (M_soll), the corresponding angular acceleration (ω_punkt_soll), the corresponding angular velocity (ω_soll) and the for the laying of necessary current (I_soll) for the drive of the yarn guide as set values. Thus, for each angular position (φ_soll) of the thread guide, the controller also has information about the moment (M_soll), the angular acceleration (ω_punkt_soll), the angular velocity (ω_soll) or the necessary drive current (I_soll) before. Due to the precalculated laying curve, the control or the controller can thus prevent an overshoot of the yarn guide at the reversal points of the coils as well as other laying errors at high yarn laying speeds. Of course, this only applies as long as no disturbances occur.

So that the setpoint values of the moment (M_soll), the angular acceleration (ω_punkt_soll), the angular velocity (ω_soll) and the laying flow (I_soll) do not have to be stored in addition to the desired size of the angular position (φ_soll) for each laying curve of a winding structure, are determined via a system model, which simulates the real controlled system in terms of control engineering or mathematics, from the respective angular position (φ_soll) calculates the missing variables for the ideal controlled system. The setpoint of the angular positions (φ_soll) on the one hand goes directly into the controller and on the other hand into the model of the ideal controlled system in parallel. The torque (M_setpoint) corresponding to the respective angular position (φ_setpoint), the corresponding angular acceleration (ω_point_setpoint), the corresponding angular velocity (ω_setpoint) and the necessary routing current (I_setpoint) are determined on the basis of the ideal controlled system and are passed as output variables of the system model into the controller as another Setpoint variables for the multi-variable control.

Conveniently, the controller also the comparable actual values, which consist of the actual angular position (φ_ist) of the thread guide, the current moment (M_ist), the current angular acceleration (ω_punkt_ist), the current angular velocity (ω_ist) of the yarn guide and the existing laying current (I_ist) , to the incoming setpoints available. Since in practice a number of disturbances on the actual controlled system act, needed the control additionally the actual values of these variables in order to be able to compensate for a deviation of the actual values from the desired values. These actual values are detected directly by additional sensors or sensors or indirectly calculated using other physically measurable parameters and forwarded to the controller via feedback. However, the exact measurement of the moment referred to as torque and the current in the thread transfer drive (I_ist) is technically very complicated and expensive. Also, the angular velocity and angular acceleration could be generated by the derivative of the signal that the angle sensor or transducer provides. Since the control should advantageously be digitized for the implementation of the calculations in a microprocessor, the derivation of a digital value produces a strongly noisy signal. For this signal to be usable, filtering would be unavoidable. However, this would result in a large loss of momentum.

Therefore, a further measure improving the invention provides that the comparable actual values (to the setpoint values of the controller) can be determined by a state observer according to the real controlled system as so-called estimated values (φ_dach, M_dach, ω_punkt_dach, ω_dach, I_dach) and sent to the controller ( be forwarded by the already mentioned feedback), wherein the state observer at least one manipulated variable (u) of the controller and the actual angular position (φ_ist) are present as input variables. The state observer itself is another time-invariant model, whereby the desired actual values can be reconstructed. Although the values obtained by the observer of the state are called "estimated values", they are by no means "estimated values" but rather specific or calculated values. In other words, the connected observer makes it possible to communicate the internal states as they exist in the real controlled system sufficient accuracy to determine and provide the controller. As a result of this measure, it is possible to dispense with the additional sensor system described above, since only the actual value of the angular position (φ_act) has to be detected with the already existing angle sensor. Consequently, the abovementioned disadvantages of the additional measuring sensors can also be prevented by the condition observer employed. This can be used on the existing technical structure or the structure of the thread-laying drive.

In a further preferred embodiment, the status observer is designed as a Luenberger observer or as a so-called asymptotic observer. With regard to the Luenberger observer, for example, Otto Föllinger "Control Engineering", Dr. Ing. Alfred Hüthig Verlag Heidelberg 1990, referenced. On pages 502 et seq. Of the book, it will be explained in more detail how the observer parameters are determined and how an observer is designed by means of complex transfer functions for a single system or multi-sizing system, as in the present case. The proposed Luenberger observer has the advantage that with its help the system state can be reconstructed exactly after an initial disturbance. This applies in particular to disturbances which repeat themselves from time to time, since the observer is able to recapture the new system state. Consequently, the use of the Luenberger observer allows precise control of the thread transfer drive even in the event of possible disruptions.

Appropriately, a weighting of the individual desired and actual values by weighting blocks is provided separately in each case in the controller, whereby the control quality of the controller can be further improved in a simple manner. The respective weighting of the individual values can be determined experimentally, for example.

Furthermore, it may be advantageous that the individual nominal and actual values can be weighted not only linearly but also potentially or exponentially by the weighting modules. As already described in the section above, the control quality can be further increased in a simple manner by this measure.

The control differences of the individual setpoint / actual values can be detected by the controller, for example, after a weighting has been carried out, and the controller can carry out a correction of at least one manipulated variable (u) for a control difference not equal to zero. Thus, it is possible to use the proposed controller to map a control algorithm that carries out a target / actual comparison of the control variables used with a possible weighting of the individual variables and at least one control variable (u) newly determined or calculated, if there is a control difference.

In a further alternative embodiment of the invention, an angle sensor for detecting the actual angular position (φ_ist) of the thread guide is used, which has an analog Hall sensor and a magnet, in particular a permanent magnet, which are in operative connection with each other. Further details and application examples are the DE 103 54 587 A1 refer to. Of course, however, an optical (digital) angle sensor for detecting the actual angular position (φ_ist) of the thread guide can also be used instead of the analogue Hall sensor.

A computer (microprocessor or computer), which simulates at least the system model and / or the state observer control technology or mathematically, makes it possible to implement the present invention inexpensively and easily. If such a computer is used, it can also be used for the controller. This allows the simplify technical design of the invention further, and save additional costs.

In order to optimize the performance of a textile machine, which is used to create bobbins and which is equipped with the thread laying drive according to the invention, all existing workstations are equipped with the thread laying drive according to the invention.

The invention enables high thread laying frequencies while avoiding installation errors. Preferably, as far as possible, the existing technical structures of the thread-laying drive are utilized.

The angular position (φ_soll) is advantageous as a setpoint on the one hand directly into the controller and on the other hand as an input to an upstream system model, which simulates the real control system control technology or mathematically. By means of this upstream system model further setpoint values, such as the angular velocity (ω_soll) corresponding to the angular position, the corresponding moment (M_soll), the corresponding angular acceleration (ω_punkt_soll) and the necessary laying current (I_soll) are determined for a multi-variable control of the controller. Thus, a precise and fast control of the thread transfer drive is possible, as long as no disturbances occur in the system.

Since, in practice, disturbances can never be completely ruled out, it is advantageously provided while maintaining the existing technical structures of the thread laying drive that the angular position (φ_dach) can be determined from the manipulated variable (u) of the controller and the actual angular position (φ_ist) of the yarn guide via a state observer. the thread guide, the corresponding angular velocity (ω_dach) of the thread guide, the corresponding moment (M_dach), the corresponding angular acceleration (ω_punkt_dach) and the current required for laying power (I_dach) of the drive are generated as estimated values and the controller as further input variables (by a feedback) available stand. In this way, the regulation also reacts to any disturbances that are thus compensated.

Not all five input variables are required for the control in each case. For example, three input variables can be used for a regulation according to the invention, such as the angular position, the angular velocity and the current. But it is also possible to use more than five input variables for the control. The more input quantities are received, the greater the achievable control accuracy. However, the effort for the control increases with increasing number of input variables.

• Figur 1 ein Blockschaltbild zum beispielhaften Regelungsaufbau des Fadenverlegeantriebs.

Further advantages, features and details of the invention will become apparent from the following description and the drawings to an embodiment of the invention. The features mentioned in the claims and in the description may each be essential to the invention individually or in any desired combination. It shows:

• FIG. 1 a block diagram of exemplary control structure of the thread laying drive.

In FIG. 1 is a block diagram for the control structure of the thread laying drive with a state observer 12 shown. In this case, from the setpoint generator 1, the predetermined angular position (φ_soll) as setpoint value 2 directly enters the controller 4. Also, this angular position (φ_soll) as Input variable used for the system model 3. Due to the track model 3, the real controlled system 10, which consists of the final stage of the yarn guide drive and the further electromechanical yarn laying drive, shown as an ideal controlled system. Thus, the additional setpoints 2, namely the corresponding moment (M_soll), the required laying current (I_soll), the corresponding angular velocity (ω_soll) and the corresponding angular acceleration (ω_punkt_soll) of the yarn guide, can be generated as additional input variables for the controller 4. In the controller 4, a weighting of the incoming nominal quantities 2 can be provided separately for each nominal variable 2 individually by weighting modules 5.

So that the controller 4 can also respond to possible disturbance variables 14 which act on the real controlled system 10, actual values which are present at the end of the real controlled system 10 are also used as the basis for a comparison with the desired values 2. For this purpose, the actual values are fed back to the controller 4. In the present case, however, the desired actual values are supplied as estimated values 13 from a state observer 12 to the controller 4, since the existing actual values can only be determined with a disproportionate effort. Namely, the state observer 12 makes it possible to determine the comparable estimated values 13 to the required actual values on the basis of the manipulated variable 9 (u), which represents a voltage, and the controlled variable 11, which consists of the actual angular position 11 (φ_ist) of the thread guide. These actual values consist of the actual angular position 11 (φ_act), the corresponding moment (M_act), the associated angular velocity (ω_act) of the thread guide, the associated angular acceleration (ω_point_act) and the current routing current (I_act). Accordingly, the state observer 12 supplies the estimated values 13 of the angular position 11 (φ_dach), the corresponding moment (M_dach), of the associated Angular velocity (ω_dach) of the thread guide, the associated angular acceleration (ω_punkt_dach) and the laying current (I_dach). Consequently, the use of the state observer 12 does not require the technical structure or the structure of the thread laying drive to be changed.

The estimated values 13 determined by the state observer 12, as already mentioned, enter the controller 4 as further variables. This makes it possible to dispense with determining a plurality of different actual actual values by measuring at the end of the real controlled system 10. Furthermore, a weighting of the feedback estimated variables 13 in the controller 4 can take place by means of existing weighting modules 6. The resulting variables are processed in arithmetic units 7 and compared with the likewise weighted setpoints 2 by a target / actual comparison 8. The comparison of the setpoint / actual values usually takes place by difference formations. If this result deviates from zero, the controller will make a correction of at least one manipulated variable 9 (u) for the real controlled system 10. This causes the thread guide again reaches its predetermined angular position (φ_soll).

The control variables 9 (u) output by the controller 4 are forwarded to the real controlled system 10, whereby the angular position of the yarn guide is changed. The actual angular position 11 (φ_ist) of the yarn guide is detected by an angle sensor or sensor, not shown, and represents the actual controlled variable 11 of the illustrated control system. This controlled variable 11 is the only, actually determined actual value of the entire control system.

As mentioned above, it is also conceivable to detect the required actual values by additional sensors or encoders and to pass them on to the controller 4 via a feedback.

LIST OF REFERENCE NUMBERS

1

Setpoint generator

2

Nominal values / values

3

Track model with ideal controlled system

4

regulator

5

Weighting blocks for weighting the setpoints

6

Weighting blocks for weighting the actual or estimated values

7

calculator

8th

Target / actual comparison

9

manipulated variable

10

real or actual controlled system (output stage + electromechanical thread laying drive)

11

Actual value / controlled variable

12

observer

13

estimated value

14

disturbance

Claims (8)

1. Thread displacement drive, in particular for a workstation of a textile machine, comprising a thread guide and an electric motor single drive provided for this and an angle sensor for detecting the actual angular position (ϕ_ist) of the thread guide and a controller (4), by means of which at least one actuating variable (9) (u) for an output stage of the electric motor single drive can be predetermined, to drive the thread guide,
   characterised in that
   the controller (4) comprises a multivariable control system to precisely control the actual angular position (ϕ_ist) of the thread guide by means of at least one actuating variable (9)(u) and in that a plurality of the following input variables

   i) the predetermined angular position (ϕ_soll) of the thread guide,

   ii) the corresponding torque (M_soll) of the thread guide,

   iii) the corresponding angular acceleration (ω_punkt_soll) of the thread guide,

   iv) the corresponding angular speed (ω_soll) of the thread guide, and

   v) the current (I_soll) of the drive necessary for displacement enter the controller (4) as desired values (2),

   in that after the control section (10) a feedback is present, which provides the controller (4) with comparable actual values to the desired values (2),
   wherein the actual values are recorded directly by additional sensors or measurement sensors or indirectly by means of other physically recordable measurement variables.
2. Thread displacement drive (1) according to claim 1, characterised in that a section model (3) is present, which simulates the control section (10) (current output stage + drive of the thread displacement system) and predetermines a plurality of the further input variables of the controller (4) of the thread guide from the predetermined angular position (ϕ_soll).
3. Thread displacement drive (1) according to any one of claims 1 or 2, characterised in that the comparable actual values to the desired values (2) after the control section (10) can be determined as so-called estimate values (13) by a status observer (12) and are available to the controller (4), and at least one actuating variable (9) (u) and the actual angular position (11) (ϕ_soll) are used as input variables for the status observer (12).
4. Thread displacement drive (1) according to claim 3, characterised in that the estimate values (13) generated by the status observer (12) comprise

   i) the predetermined angular position (ϕ_dach) of the thread guide,

   ii) the corresponding torque (M_dach) of the thread guide,

   iii) the corresponding angular acceleration (ω_punkt_dach) of the thread guide, (ϕ_dach)

   iv) the corresponding angular speed (ω_dach) of the thread guide, and

   v) the current (I_dach) of the drive necessary for displacement.
5. Thread displacement drive (1) according to claim 3 or 4, characterised in that the status observer (12) is a Luenberger observer.
6. Thread displacement drive (1) according to any one of claims 1 to 5, characterised in that, in the controller (4), a weighting of the individual desired and actual values by weighting components (5, 6) is provided separately from one another in each case.
7. Thread displacement drive (1) according to claim 6, characterised in that the weighting components (5, 6) comprise a linear, potential or exponential weighting of the individual desired and actual values.
8. Thread displacement drive (1) according to any one of claims 1 to 7, characterised in that the angle sensor for detecting the actual angular position (11) (ϕ_ist) of the thread guide has an analogue Hall sensor and a magnet, in particular a permanent magnet, which are in operative connection with one another.

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