DE3308671A1 - Control loop for a drive - Google Patents

Abstract

For a drive control loop having at least one transmitter which supplies a position signal and a change-of-position frequency signal, such as, for example, an incremental displacement sensor followed by a counter, the adaptation to non-linear changes in nominal or actual value has been created by the position signal being changed by values of a function generator. Digital values can be advantageously used for calling up fixed values from a digital read-only memory. In particular, this results in the possibility of influencing the frequency of pulse frequency signals. Such signals can be added together to form a transformed position signal (or an associated position deviation) and they can also provide a corresponding speed of rotation or speed control by way of replacement or complement.

Description

Patent attorneys

Dipl.-Ing. Dr. iur. V. buses

Dipl.-Ing. Dietrich Busse

Keller Spezialtechnik-Pyro Werk GmbH Dipl.-mg. Egon Bünemann

Carl-Keller-Strasse 2-10 D-4500 Osnabrück

., __ .. _,,, .. _,, Wholesale ring β PO Box 1226

4530 Ibbenbueren-Laggenbeck _. ".."""., _{CQ =} " _O ,

2-2 telephone (05 41) 58 60 81 and 586082

Telegrams' Datgawar Osnabrück

March 10, 1983 EB / Rh

Control loop for a drive

The invention relates to a control loop according to the preamble of claim 1.

Control loops of this type are known, for example, as position control loops, which often have a subordinate speed control or speed control loop and, if necessary, also a subordinate current control loop - for electric drives - exhibit. Often such control loops are equipped with incremental encoders that primarily provide a path change signal in the form of a pulse train and thus a frequency signal, the pulses with the correct sign Count can be added to a position signal.

While the accuracy and reproducibility of such regulations usually leaves nothing to be desired, there are often difficulties in the static and dynamic handling of such a control loop when For example, non-linearities have to be taken into account and special dynamic tasks are pending. 20th

Accordingly, the object of the invention is to create a control loop for a drive which can be statically and dynamically aligned well even to difficult non-linear control tasks.
25th

According to the invention, this object is achieved with a control loop

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solved according to claim 1. In this control loop, the one controlled as a function of the position signal comes Function generator has the special role of influencing the signal that is passed on depending on the position and thus an opportunity to intervene to give in terms of static and dynamic influence. Especially with the widespread digital position detection for the setpoint and / or actual value signal, the function generator can be designed as a read-only memory The output signals that can be specified differently according to position input values or input value ranges supplies.

The action on the frequency signal, for example the pulse frequency signal, is particularly useful which is then both a position signal that can be generated therefrom again by integration in the sense of a position value correction such as also the frequency directly in the sense of a dynamic control loop influence is changed.

Further features and advantages of the invention emerge from the claims and the following description, in which an embodiment of the subject matter of the invention based on a drawing is explained in more detail. In the drawing show:

Fig. 1 is a control circuit diagram for a drive in

Cascade control with position, speed and current control loop and
FIG. 2 a more detailed scheme of the position control loop from FIG. 1.

The control circuit to be described in more detail below was developed for a veneer machine in which the Veneers are removed from a log, i.e. flat, secant-shaped running towards the circular cross-section of a log Veneer sheets are created which, in contrast to a peeled veneer, have a good grain

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permit.

To do this, a tree trunk is clamped parallel to a fixed knife and then across to itself to one Cutting motion moved against the knife. The tree trunk performs periodic cutting movements in relation to the stationary one Knives that swing out, for example, from a revolving drive via a crank. The reciprocating Movement is non-uniform, especially at the turning points the speed decreases.

Adjusted to this non-uniform cutting speed, belt conveyors must run in connection with the knife so that the veneer sections, cut as thinly as possible for reasons of high yield, are transported away non-destructively can be.

• To make matters worse, the speed of the belt conveyor In the synchronization with the movement of the trunk, corrections or special speed ranges are still required in certain areas and that from a practical point of view it is inexpedient, the movement wanting to record the tree trunk yourself - a setpoint generator on the crank drive is simpler and more protected to be provided, the movement of which, however, is non-linearly related to that of the tree trunk.

In this case, an actual value for the movement of the associated belt conveyor is from its own regularly available . Remove motor as belt drive.

In the present embodiment, both for the setpoint generator as provided for the actual value encoder, incremental Weqgeber that initially deliver a pulse frequency signal that can then be added to a path signal or position signal. It is understood that in a similar way a digital encoder can be used, which is a parallel digital signal

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generated, with known means from continuous or frequently keyed digital signals pulse trains can be derived as a change signal.

The control loop illustrated as a whole in FIG. 1 has a setpoint generator 1 and an actual value generator 2, whose Signals are fed to a position controller 3. The control signal is fed to a speed controller 4, the Speed actual value from a tachometer generator 5 is obtained. The speed control signal is sent to a current controller 6, which receives a current actual value signal from a current transformer 7 from an actuator 8 for a drive motor 9, the drive motor 9, together with its actuator 8 (e.g. a thyristor control), the actual route of the control loop. Insofar ^ corresponds to the one described Control loop essentially previously known control loops with digital or incremental position control.

The overview in Fig. 1 also shows that the output signal of the setpoint generator is branched off. On the one hand, it becomes a function generator 10 fed, the influence on the position control in position controller 3 and on the speed control takes by the encoder signal changed in a control loop element 11 and then directly is entered into the speed control for speed controller 4. This has proven to be extremely useful for influencing the dynamic properties of synchronization.

The detailed partial representation of the control loop described above leaves in Fig. 1 on the one (left) side the setpoint generator 1 and the actual value generator 2 and on the other side recognize the speed controller 4.

Setpoint and actual value transmitter 1 or VK 2 are as incremental Rotary encoders are designed that output regularly changing signals during rotation for each given radian measure. Every incremental Depending on the position, the encoder supplies two mutually

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put out signals that allow forward and backward movements to distinguish. This distinction is made for the setpoint generator 1 in a direction recognition 12 and for the actual value transmitter 2 in a direction detection 13. For other processing, the two output signals of each pulse generator combined to form a common signal in a pulse shaper stage 14 or 15, respectively in which a multiplication of the pulses is to be provided if necessary, the following in the frequency range can enable finer processing. Additional reset pulses, also known as zero pulses, can be used be taken via the reset switch 16 either from the setpoint or actual value, depending on whether the to be adjusted Distortion of the motion sequence on the target value acquisition side (as in this example) or on the actual value acquisition side (for example a cutter with a cutting tool driven by a crank). This provides a reference mark for the subsequent addition of the pulses to a load signal, which enables a resetting during operation, possibly creeping summing errors. The setpoint generator 1 outgoing pulses are fed to a counter 17, which in addition to the reset signal · also from the direction detection 12 receives a sign information and can thus count with the correct sign. This counter creates a number signal, which is representative of the angular position of the setpoint generator 1.

In the specific case of the production of sliced veneers, however, the angular position of the setpoint generator would not be suitable Specification for the movement of a conveyor connected to the knife for the sliced veneer. While the cutting would have to be synchronized with the movement of the trunk or with the accumulation of the veneer, Q where the crank produces at least one non-linearity, and during the return of the trunk to the beginning of a new one j> the cutting movement should by no means run back, at best stand still. Preferably, however, in

rn PDPV these areas a slow advance transport of the conveyor

^ provided. For this purpose, the rotating at uniformly

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^{Change σ} crank drive and setpoint adjuster T evenly

Function generator 10 is provided which, according to the detailed illustration in FIG. 2, not directly (as in FIG. 1), but is only indirectly connected to the setpoint generator 1 via the counter 17. It is a read-only memory in the form of a ROM (read only memory), which has recently been available inexpensively as a semiconductor component and is also available easily programmable. This read-only memory enables either, depending on the memory capacity each individual position value of the counter 17 or more or less finely graded value groups of the counter Specify output values arbitrarily. In the present case, value groups are formed to which certain output values of the function generator 10 are assigned. The output values form factors for the pulse frequency that is generated by the pulse shaper 14 goes out. The pulse frequency signal from the output of the pulse shaper 14 is not only the counter 17, but also fed to a frequency converter 18, which performs a multiplication with that fed to it by the function generator 10 Value. It goes without saying that other frequency conversions, for example of an additive type, are also possible. The reshaped The frequency signal also passes through a correction element 19, in which it is, if necessary, with a constant frequency factor is changed, which is to be entered via an input circuit 20, and then arrives into a counter control 21 and then into a comparison counter 22nd

The counter control 21 and the comparison counter 22 are also acted upon with the pulse frequency signal, which from the pulse shaper 15 on the part of the actual value transmitter. This signal is not influenced by one Function generator, but it is also influenced by a correction element 23, which corresponds to a scale input is excited via an input circuit 24 for frequency multiplication. Thus, both the pulse frequency of the Setpoint transmitter as well as that of the actual value transmitter on the counter control, whereby the signed evaluation is thereby

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it is made possible that the direction recognition 12 or 13 Sign signals are input to the counter control 21, so that a four-quadrant counting takes place in the comparison counter 22. The difference signal formed there presents the Positional deviation between the belt conveyor drive, measured by the actual value transmitter 2, and an artificial one, from the setpoint transmitter 1 derived and with the help of the function generator 10 converted setpoint. This positional deviation is converted into a Analog value converted with the aid of an analog digital converter 25 and then the speed controller or speed controller 4 supplied.

The speed controller 4 receives an actual speed signal from a tachometer via a feedback 26 (see FIG. 1).

In addition, the speed controller receives a connection branch 27 an additional speed signal from the setpoint side. Here is the transformed pulse frequency signal branched off from the output of the frequency converter 18 and fed to a frequency-voltage converter 28. This supplies a voltage proportional to the pulse frequency, which is also driven to negative values with the correct sign can be, since the frequency-voltage converter 28 also the output signal of the -. 'Direction detection 12 is fed will. The activation factor is expediently provided to be adjustable and in particular also controlled simultaneously with the multiplication in the correction element 19, including a signal connection from the input circuit 20 to the frequency-voltage converter is used.

It has been shown that this connection to the speed controller 4 on = enables much faster regulation without reducing the stability of the control loop will. Rather, a very stable control loop with low control deviations could be created with it.

In particular, however, it has become possible to not linearly vary

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interdependent situation and movement signals such as the Rotary position of a crank drive and the setpoint to be derived from it for a conveyor behind the crank-driven one To make machine tools easy to control and for this a clear and effective drive control to create. Corresponding non-linear deformations can be illustrated as an alternative as well as in addition for setpoint conversion when converting the actual value.

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Claims (1)

Patent attorneys Keller Spezialtechnik-Pyro Werk GmbH Dipl.-ing. Dr. iur. v. buses 7-10 Dipl.-Ing. Dietrich Busse L TU Dipl.-Ing. Egon Bünemanr 45 30 Ibbenbueren-Laggenbeck D-4500 Osnabrücl GroOhindtlsring β Posi'ach 122C FernsDr * Cher (0S41) 58 80 81 υ 58 60 S! Telegrimma: patgewar osnabruct March 10, 1983 EB / Rh Patent claims: Control loop for a drive, in particular one with a predetermined variable sequence of movements to be synchronized conveyor or tool drive, with a setpoint and an actual value transmitter, at least one of the transmitters for the setpoint or actual value, a position signal and a frequency signal depending on the supplies associated change in position, characterized in that the position signal is fed to a function generator (10) whose output signal is applied as a conversion signal to a frequency converter (18) for the frequency signal is, and 'that the converted frequency signal of the drive control (4,22) is used. 2. Control loop according to claim 1, characterized in that the encoder (1) is a pulse generator, ^ .er a pulse-shaped Frequency signal supplies. 3. Control loop according to claim 1 or 2, characterized in that the position signal by integration (17) of the Frequency signal is formed. 4. Control loop according to claim 2 or 3, characterized by the frequency signal to a digital position signal integrating counter (17). 5. Control loop according to one of claims 1 to 4, in which the position signal is formed in digital form, characterized in that the function generator is a digital read-only memory (10) for uniform signals. 6. Control loop according to one of claims 1 to 5, characterized characterized in that the converted frequency signal is summed for a position control. 7. Control circuit according to claim 6, characterized in that both the setpoint value and the actual value transmitter (1,2) each provide a frequency signal and that the frequency signals a counting device (21, 22) to form a positional deviation. 8. Control loop according to claim 7, characterized in that the counting device (21, 22) is a four-quadrant counter includes. 9. Control loop according to claim 8, characterized in that the encoder (1,2) is designed as a two-track incremental encoder are, whose pulse frequency signals are each fed to a direction recognition (12, 13), which each supplies a sign signal for the four-quadrant counter (21,22). 10. Control loop according to one of claims 6 to 9, there- characterized in that the position control is a speed control loop (4,5) is subordinated and that this speed control loop is used as the speed or speed setpoint a frequency signal belonging to the position setpoint is fed to the position control in addition to the control deviation. 11. Control loop according to claim 10, characterized in that the controller (4) for the speed control loop is an analog controller and that the frequency signal is input as a voltage analogous to the frequency. 12. Control loop according to one of claims 1 to 11, characterized characterized in that the frequency converter (18) as * Β * mmm Λ Β - 3- Frequency multiplier is formed. 13. Control loop according to one of claims 1 to 12, characterized by an input circuit (20,24) for Correction factors for the frequency signal