阅读说明：本技术 用于控制长定子直线电机的方法 (Method for controlling a long stator linear motor ) 是由 S·弗利克斯德 S·胡贝尔 A·阿尔默 于 2020-02-28 设计创作，主要内容包括：本发明涉及一种用于控制长定子直线电机的方法,为了改善对长定子直线电机(2)的控制,在运动方向(r)上沿着运输线路(20)在第一测量段(21)中确定第一测量值(m1)并且在第二测量段(22)中确定第二测量值(m2),其中,所述第一测量段(21)在运动方向(r)上与所述第二测量段(22)在交叠区(B)交叠,而且所述第一测量值(m1)和所述第二测量值(m2)描绘物理参量(G)的相同的实际值(X)。依据在所述第一测量值(m1)与所述第二测量值(m2)之间出现的偏差来确定所述长定子直线电机(2)的运行参数(P)。(The invention relates to a method for controlling a long-stator linear motor, in order to improve the control of the long-stator linear motor (2), a first measured value (m1) is determined in a first measuring section (21) and a second measured value (m2) is determined in a second measuring section (22) along a transport line (20) in a direction of movement (r), wherein the first measuring section (21) overlaps the second measuring section (22) in an overlap region (B) in the direction of movement (r), and the first measured value (m1) and the second measured value (m2) represent the same actual value (X) of a physical variable (G). Determining an operating parameter (P) of the long stator linear motor (2) as a function of a deviation occurring between the first measured value (m1) and the second measured value (m 2).)

1. A method for controlling a long stator linear motor (2), wherein a first measured value (m1) is determined in a first measuring section (21) and a second measured value (m2) is determined in a second measuring section (22) along a transport line (20) in a direction of movement (r), characterized in that the first measuring section (21) overlaps the second measuring section (22) in an overlap region (B) in the direction of movement (r); the first measured value (m1) and the second measured value (m2) describe the same actual value (X) of the physical quantity (G); and determining an operating parameter (P) of the long stator linear motor (2) as a function of a deviation occurring between the first measured value (m1) and the second measured value (m 2).

2. Method according to claim 1, characterized in that the measuring sections (21, 22) are arranged on opposite sides of the transport line (20).

3. Method according to claim 1 or 2, characterized in that the measuring sections (21, 22) are arranged on the same side of the transport line (20).

4. A method according to any one of claims 1 to 3, characterized by determining an approximation of the actual value (X) as the operating parameter (P).

5. Method according to claim 4, characterized in that the first or the second measured value (m1, m2) is selected as the approximation of the actual value (X).

6. The method according to claim 4, characterized in that the first or the second measurement value (m1, m2) is selected based on a classification of the respective measurement value.

7. The method according to claim 5 or 6, characterized in that the first or the second measurement value (m1, m2) is selected based on an expected accuracy of the respective measurement value.

8. A method according to claim 4, characterized in that the first and the second measured values (m1, m2) are each provided with a weighting factor (f1, f2), and that an approximation of the actual value (X) is determined from the first and the second measured values (m1, m2) and the respective associated weighting factors (f1, f2) as the operating parameter (P).

9. Method according to claim 8, characterized in that the weighting factors (f1, f2) comprise model factors which are determined by the magnitude of the deviation of the associated measured values (m1, m2) from a reference model.

10. The method according to one of claims 8 to 9, characterized in that the weighting factors (f1, f2) comprise geometric factors which are determined by the position of the respective measured value (m1, m2) within the associated measured segment (21, 22).

11. The method according to any of the claims 8 to 10, wherein the weighting factors (f1, f2) comprise statistical factors, the statistical factors being determined by a statistical distribution function.

12. Method according to any of claims 1 to 11, characterized in that the occurrence of disturbances and/or faults and/or wear on the long stator linear motor (2) is determined as an operating parameter (P).

13. The method according to any one of claims 1 to 12, characterized in that the position of a transport unit (1) on the transport route (20) is determined as a first and a second measured value (m1, m2), respectively.

14. Method according to any one of claims 1 to 12, characterized in that the speed and/or acceleration of a transport unit (1) on the transport line (20) is determined as a first and a second measurement value (m1, m2), respectively.

15. Method according to any of claims 1 to 12, characterized in that temperature and/or current are determined as first and second measured values (m1, m2), respectively.

16. A data processing apparatus, comprising:

a memory having stored therein computer-executable instructions; and

a processor configured to execute computer-executable instructions, wherein the processor, when executing the instructions, implements the method of one of claims 1 to 15.

17. A computer-readable storage medium having stored therein computer-executable instructions which, when executed by a processor, implement the method according to one of claims 1 to 15.

Technical Field

The invention relates to a method for controlling a long-stator linear motor, wherein a first measured value is determined in a first measuring section and a second measured value is determined in a second measuring section along a transport path in a movement direction.

Background

The long stator linear motor (LLM) comprises a plurality of electric drive coils arranged side by side, which are arranged in a stationary manner along the transport path on one, two or more sides and form one or more stators. A plurality of exciter magnets are also arranged on the transport unit as permanent magnets or as electrical coils or as short-circuit windings, respectively. These magnets are usually mounted on the transport unit on one side, on both sides or on more sides in the direction of movement, so that they can interact with the drive coils of the stator. The long stator linear motor can be implemented as a synchronous motor, self-excited or separately excited, or as an asynchronous motor. By the interaction of the (electromagnetic) fields of the magnet and the drive coil, a thrust force acts on the magnet of the transport unit, which in turn moves the transport unit in the direction of movement. This is achieved by manipulating the individual drive coils to adjust the magnetic flux by which the magnitude of the propulsive force is influenced. Long stator linear motors are increasingly used as a replacement for conventional continuous conveyors or rotary to linear drive units (e.g. rotary motors on conveyor belts, chains, etc.) in order to meet the requirements of flexible modern logistics units. Of course, the transport units must be guided along and held on the transport line in a suitable manner. In this case, any guide element of the transport unit itself can interact with the guide element of the transport line, for example rollers, wheels, sliding elements, guide surfaces, etc. can be used. These guide elements may also be arranged on one side, on two sides or more. In order to adjust the position of the transport unit on the stator, in addition to the theoretical position, an actual position is of course also required. The device for detecting the actual position and for specifying the setpoint position can be integrated into the long-stator linear motor or can also be implemented externally.

The position, speed, acceleration or other physical quantities of the transport units of the entire transport line can be determined overall. This can be interpreted as setting up a measurement section that covers the entire transport line. The measuring section comprises one or more measuring sensors for detecting measured values. The measured values each represent the actual value of the physical variable. For example, the position of the transport unit within the measuring section can be determined as a measured value, whereby the actual position is plotted as a physical variable. This can be achieved directly by means of a position sensor in the measuring section. A position observer may also be provided which determines the position based on other information, such as voltage and current.

If only one measuring section is provided, the transport route can therefore have only one-dimensional topology, that is to say a circle or a line. The transport route can then correspondingly not comprise switches, since the measuring sections otherwise have to overlap themselves. Correspondingly, the transport path of the long-stator linear motor can also consist of a plurality of measuring sections. In this case, a measuring section usually, but not necessarily, covers a transport section or a part of a transport section, respectively. A transport section represents a modular part of the transport line and comprises a plurality of drive coils. These measuring sections are usually spaced apart from one another or arranged adjacent to one another along the transport line in the direction of movement.

In order to determine the global actual position of the transport unit, the measurement section in which the transport unit is located can first be determined in each case. The actual position of the segment on the corresponding measurement section can further be determined. The individual segment actual positions are combined to a global actual position on the transport route. In this way, a specific global actual position, for example with reference to the selected reference point, can be assigned to the transport unit. If these measurement sections together completely cover the transport path of the linear motor, a clear actual position of the reference (arbitrary) reference point can be assigned to the transport unit at each point in time. This is called complementary sensor data fusion and is known for example from US 6876107B 2. The individual measuring sections are complementary to one another and are arranged next to one another without gaps.

Disclosure of Invention

The aim of the invention is to improve the control of a long-stator linear motor.

According to the invention, this object is achieved by: the first measurement section overlaps the second measurement section in an overlap region in the direction of movement, wherein the first and second measured values represent the same actual value of the physical variable and an operating parameter of the long-stator linear motor is determined as a function of a deviation occurring between the first and second measured values.

Since these measurement segments overlap, redundant measurement values are generated in the overlap region. The respective measured value can be determined or observed in the associated measuring section by the sensor or also by the cooperation of the sensors in the respective measuring section. It is determined whether and how much the first measured value of the first measured section deviates from the second measured value of the second measured section, wherein tolerances can of course be specified. If a deviation occurs, the operating parameter is determined using the deviation. The first and/or second measured values may be used to determine an operating parameter. The first and second measured values themselves only have to represent the physical variable. This does not mean: these measured values must directly exhibit the same physical parameter. Thus, for example, the first measured value can directly describe the actual position and the second measured value can describe the current, from which the actual position is determined.

The first measured value therefore directly represents the actual position as the physical variable, while the second measured value indirectly represents the actual position as the physical variable.

The method according to the invention is not limited to two measured values, each from an associated measuring section. One measurement value each from more than two overlapping measurement segments may also be used to determine the operating parameter or a plurality of measurement values from two or more overlapping measurement segments may also be used to determine the operating parameter.

These measuring sections may be arranged on opposite sides of the transport line.

In this way, the measuring sections can be arranged completely spaced apart from one another in a transverse direction transverse to the direction of movement, although the overlap region is obtained as viewed in the direction of movement. This arrangement is encountered particularly in the case of a long stator linear motor of the double comb type. Double comb long stator linear motors (Doppelkamm-langstatorlinermotor) are characterized by two drive sides arranged along the transport line, wherein one stator is provided per drive side. Thus, a drive coil is arranged on each side. Therefore, excitation magnets are also provided on the transport unit on both sides, which excitation magnets each interact with a drive coil on one side.

These measuring sections can also be arranged on the same side of the transport line.

The following layout may be set: the sensors of the two measuring sections are arranged one above the other in the direction of movement. However, the sensors belonging to the respective measuring sections are often not arranged overlapping. However, these measurement segments represent the line of sight of the sensors rather than the physical extension of the sensors themselves. In general, overlapping measurement segments mean an overlap of the fields of view of the sensors, wherein the sensors themselves may also overlap. This of course also applies to the measuring sections arranged on opposite sides of the transport line.

Of course, it is also possible to arrange a plurality of measuring sections along the transport line such that a mixture of overlapping areas on opposite sides of the transport line and on the same side of the transport line is obtained. It is also possible to compare a third measured value of a third measuring section with the first and second measured values or to compare other measured values of other measuring sections with the first and second measured values, etc.

Advantageously, an approximation of the actual value is determined as the operating parameter.

Of course, the approximation may be performed for the actual values that occur over the entire overlap region, wherein the first and second measured values are used for the respective actual values, respectively.

The first or second measured value may be selected as an approximation of the actual value.

This corresponds to a selection method which enables a particularly rapid approximation of the actual value. In this way, even if there is a failure of a measuring section in the overlap region, another measuring section can continue to provide a measured value, thereby preventing a failure of the entire long-stator linear motor.

The first or second measurement value may be selected based on the classification of the respective measurement value and/or the expected accuracy of the respective measurement value.

The first or second measurement value may be selected as an approximation of the actual value based on the measurement value or the current classification of the measurement segment. In this way, for example, a measurement value that can be considered more accurate based on the classification can be selected.

One of these measurements may also be selected based on the accuracy of the measurements. Thus, for example, it may be assumed that: the accuracy at the edge of the associated measuring section decreases, whereby the position of the determined measured value relative to the measuring section can influence the selection of the measured value. In the selection, it is also possible to consider, as a geometric factor, a decrease in the accuracy of the measured values as the distance between the sensor and the measurement object increases. In the case of opposite measuring sections, for example, the measured values of the measuring section with the transport unit closer to it can be selected.

The measurement values can also be selected using a learning algorithm, such as a neural network.

As mentioned, the actual value of the physical variable is represented by the measured values in the two measurement sections. Since there are two measured values, it is not possible to determine the actual values univocally, and these measured values are preferably processed in order to approximate the actual values. Thereby, the actual value can be determined with an improved accuracy, since not only the measurement values of one measurement segment but also the measurement values from two (or more) measurement segments are used as a basis. This is referred to as competitive sensor data fusion. The actual value to be selected may be determined based on the measured value or the current classification of the measured segment. The actual value can also be approximated, for example, by averaging these measured values.

Advantageously, however, the first and second measured values are each provided with a weighting factor, and an approximation of the actual value is determined from the first and second measured values and the respective weighting factor as the operating parameter.

Unlike the selection method, one measured value is not selected as an approximation of the actual value. More precisely, two measured values are considered, wherein the two measured values are each weighted. By using weighting factors for the respective measured values, the actual values can also be better approximated.

The weighting factors may also include a model factor that is determined by the magnitude of the deviation of the measured values from the reference model.

Thus, the model factor may be determined based on a reference model, wherein the physical property may be depicted by the model, for example. In this way, for example, the equation of motion of the transport unit can be used for model formation, and deviations of the actual motion determined from these measured values can influence the model factors. The greater the deviation between the measurement and the model, the more likely the measurement is inaccurate. The model factor may be selected based thereon. This can occur in particular in the case of opposing measuring sections, since these can overlap in the direction of movement, but can nevertheless be spaced apart from one another in the transverse direction, which makes it possible to provide different measured values with high probability.

The weighting factors may include a geometric factor that is determined by the position of the measurement values within the measurement segment.

For example, it may be assumed that: the accuracy of the measured values at the edge of the associated measuring section decreases, whereby the position of the determined measured values relative to the measuring section can influence the geometry factor. Thus, the measured values at the edge of a measurement section are weighted lower than the measured values at the center of the measurement section, for example. It is also possible to consider, as a geometric factor, a decrease in the accuracy of the measured values as the distance between the sensor and the measurement object increases. In the case of opposite measuring sections, for example, the measured values of the measuring section with the transport unit closer to it can be weighted higher.

The weighting factors may include statistical factors that are determined by a statistical distribution function.

The statistical factor may, for example, take into account a parameterized random distribution of the measurement signals, wherein the variance of these measurements may be estimated. This can be achieved in particular when determining the actual position, by assuming: the variance increases as the distance between the disk of the transport unit and the position sensor increases. This is particularly useful in combination with geometric weighting factors.

In addition, the weighting factors may also be used by learning algorithms, such as neural networks. Of course, any combination of the mentioned factors and methods may be used for determining the weighting function.

The measured positions of the transport units on the transport line can be determined as a first and a second measured value, respectively.

The actual position as an actual value can thereby be represented by the measured position as a measured value and thus the control of the transport unit can be improved, since the actual position can be determined more precisely by taking into account the measured values of a plurality of measuring sections.

Likewise, the speed and/or acceleration of the transport unit on the transport route and/or the temperature and/or the current can be determined as the first and second measured values, respectively.

The occurrence of disturbances and/or faults and/or wear on the long stator linear motor can be determined as an operating parameter from the deviation of the first and second measured values.

If a disturbance, a fault or wear occurs, the first measured value and the second measured value may deviate from each other by more than a predetermined tolerance. By this means, disturbances, faults or wear can be deduced in reverse by corresponding deviations.

These measured values can be safely detected and/or safely analyzed. "safety" may be specified according to the classification of table 10 of the DIN EN ISO13849-1:2016-06 standard, and thus single-fault safety, double-fault safety, etc. may be specified according to the safety classification.

An action may be triggered when a disturbance, fault or wear is detected. An emergency stop, outputting (e.g., acoustic or optical) signals, setting flags, etc. may be performed as actions.

A mechanical assembly failure, but also a malfunction of the measurement section (e.g. due to sensor errors or disk wear, etc.) may be considered a failure. It is likewise possible to determine parameters which are initialized in error, for example faulty specification of a measurement section, whereby the measured values of the measurement section differ correspondingly to the measured values of the overlapping measurement sections.

Incorrect assembly of the transport sections can lead to incorrect positioning of the transport units on the transport route, whereby the superordinate processes, in particular the adjustment of the position or trajectory of the transport units, can be disturbed. In this way, discontinuous control variables, unstable control loops, overcurrent faults, follow-up error cutoffs (schleppfehlerbburche) and the like are obtained. The following may also occur: the control loops are adjusted in part relative to one another, as a result of which, in turn, unstable control loops can occur and increased energy requirements can also arise. In particular, if the measuring sections each cover a transport section, such incorrect assembly of the transport section can be inferred from deviations of the measured values in the overlap region.

Similarly, disturbances, such as environmental conditions (e.g., increased temperature), can also be identified, since these disturbances affect the measured values of the sensors of the individual measurement segments. A malfunction of the measurement section or of a part of the measurement section can also be identified (sensor malfunction, disk wear, … …).

By means of the deviations of these measured values, it is also possible, for example, to detect wear of the guide elements, such as rollers, in particular in the case of oppositely situated measuring sections. In this way, on the basis of the different measured values, a change in the distance of the movable part relative to the corresponding measuring section can be identified. This allows conclusions to be drawn about wear of the guide element (e.g. roller) on one side, disk wear, demagnetization of the disk, sensor failure (e.g. sensor drift, … …) if there is a deviation in the measured values of the overlapping measuring sections.

It can also be determined that: on which side the transport unit is at a smaller distance from the transport route. This can likewise occur, for example, as a result of wear on one side. This information can be used to specifically activate the drive coils on the side with the smaller distance, whereby energy can be saved and the losses occurring can also be reduced.

The invention also relates to a data processing device, such as the processing unit, control unit or other units already present on a long stator linear motor mentioned herein. The data processing apparatus comprises a memory having computer-executable instructions stored therein; and a processor configured to execute computer-executable instructions, wherein the processor, when executing the instructions, implements the method according to the invention. Furthermore, the invention relates to a computer-readable storage medium, in which computer-executable instructions are stored which, when being executed by a processor, carry out the method according to the invention.

Drawings

The invention is explained in detail below with reference to fig. 1 to 2b, which show exemplary, schematic and non-limiting embodiments of the invention. Here:

figure 1 shows a long stator linear motor;

fig. 2a shows two measuring sections on the same side of the transport line;

fig. 2b shows two measuring sections on opposite sides of the transport line.

Detailed Description

Fig. 1 shows a long-stator linear motor 2, the stator of the long-stator linear motor 2 being embodied as an exemplary closed transport line 20. On the transport path 20, a plurality of drive coils L are arranged one after the other in the direction of movement R of the transport unit 1, which are each operated with a coil current i under the control of the control unit R during normal operation_mIs energized to generate a moving magnetic field. Coil current i through the respective drive coil L_mWhich may be substantially different for each drive coil L. The control unit R may be implemented as suitable hardware and/or as software running on suitable hardware. The drive coils L arranged side by side in the direction of movement r are arranged on a stationary holding structure 3 (only outlined in these figures) on the transport line 20. The transport line 20 can be shaped as desired depending on the application and requirements and can comprise closed and/or open line sections. The transport line 20 may be in one plane, but may also be arbitrarily guided in space.

There is usually a transport line 20 which is composed of a plurality of modular transport sections, each of which has a plurality of drive coils L. Likewise, switches can also be used in order to guide the transport unit 1 from the first transport section 20 to the second transport section.

Of course, the transport unit 1 must be guided along the transport line 20 and held thereon in a suitable manner. In this case, any guide element of the transport unit 1 itself can interact with the guide element of the transport line 20, wherein, for example, rollers, wheels, sliding elements, guide surfaces, etc. can be used. These guide elements can also be arranged partially on one side, on both sides or on more sides.

The measuring sections 21, 22 are arranged along the transport path 20 of the long-stator linear motor 2, wherein the measuring sections 21, 22 each extend over a part of the transport path 20. The measuring sections 21, 22 can extend over several successive transport sections or can be limited to only one transport section. Of course, the measuring sections 21, 22 can also project beyond more than one transport section or be considered independently of the transport section. For this reason, the measuring sections 21, 22 are considered in this description without considering the transport section. For reasons of clarity, the measuring sections 21, 22 are not depicted in fig. 1. More precisely, a part of the transport line 20 is considered in fig. 2a and 2b, wherein respectively overlapping measuring sections 21, 22 are shown.

The measuring sections 21, 22 are designed to determine one or more measured values m1, m2, wherein the measured values m1, m2 each represent the actual value X of the physical variable G. The actual position x and/or the actual speed v and/or the actual acceleration a of the transport unit 1 can be regarded as physical quantities G. The measured values m1, m2 are thereby respectively a measured position, a measured velocity or a measured acceleration, and thereby represent an actual position x, an actual velocity v or an actual acceleration a, wherein the two measured values m1, m2 do not necessarily directly represent the same physical variable G, but merely represent this physical variable.

If the actual position is determined as the physical quantity G, this can be done with reference to a reference point, wherein the reference point can be assumed to be at one of the measurement sections 21, 22, one of the transport sections or at any other point in space. Other physical variables G, such as the forces present, the currents flowing, the temperatures present, etc., can also be plotted by the measured values m1, m 2. In this way, a physical variable G, such as the actual position x, can be calculated again, which can also be realized by an observer.

The first measured value m1 may also directly represent the physical variable G, for example the actual position. This means that: the first measurement m1 is the actual position itself. While the second measured value m2 may be another physical variable, for example a current, from which the actual position is depicted as physical variable G. Thereby, the first measured value m1 directly describes the physical quantity G and the second measured value m2 indirectly describes the physical quantity G. However, both measured values m1, m2 depict the physical variable G.

Thus, magnetic field sensors, for example hall sensors, magnetoresistive sensors, can be provided as sensors. However, these sensors may also use other physical measurement principles, such as optical sensors, capacitive sensors, inductive sensors, etc. It is also possible to provide for determining the coil current i through the drive coil L_{m of}And a current sensor. As is well known, from coil current i_mFor example, the normal force and/or the propulsion force acting on the transport unit 1 can be determined. A temperature sensor may also be provided as a sensor.

Fig. 2a shows an exemplary first and second measuring section 21, 22. According to the invention, at least two measuring sections 21, 22 have an overlap B in the direction of movement r, i.e. along the transport path 20. The measuring sections 21, 22 which overlap in the overlap region B may be arranged on the same side of the transport line 20 as in fig. 2a or may also be arranged on opposite sides of the transport line 20 as shown in fig. 2B.

In both illustrated cases, the first measured value m1 is determined in the overlap region B within the first measuring section 21 and the second measured value m2 is determined in the overlap region B within the second measuring section 22. The two measured values m1, m2 represent the same actual value X of the physical variable G. In this way, the actual position X of the transport unit 1 can be plotted, for example, by the first actual value m1 of the first measuring section 21 as the actual value X. Similarly, the actual position X of the transport unit 1 can likewise be plotted by means of the second measured value m2 of the second measuring section 22 as the actual value X, i.e. as the second measured actual position.

Only one actual value X is shown in fig. 2a, B, although also further and/or other actual values X may be determined within the overlap zone B, wherein the measured values m1, m2 depicting these further and/or other actual values X are determined, respectively.

If the first measured value m1 and the second measured value m2 are different, the operating parameter P of the long stator linear motor 2 can be determined from the deviation of the first measured value m1 from the second measured value m2, whereby the operating parameter P is formed as a function of the measured values: p ═ f (m1, m 2).

In fig. 2a, 2b, this is implemented in the processing unit V as an example, but can of course also be implemented in the control unit R or other units already present on the long-stator linear motor 1, for example, instead. The operating parameters P can further be output and/or processed, for example for controlling the transport unit 1.

From the deviation of the first and second measured values m1, m2, for example, an approximation of the true actual value X can be determined as operating parameter P. This can be achieved by: the measurement sections 21, 22 are transformed into a common coordinate system. These measured values m1, m2 may be averaged or may also be provided with weighting factors f1, f2, respectively, whereby the operating parameter P is obtained as a function of the measured values m1, m2 and the associated weighting factors f1, f2, respectively: and P ═ f (m1, f 2; m2, f 2). An approximation of the actual value X can be determined as the operating parameter P. The weighting factors f1, f2 of the measurement sections 21, 22 may be specified at the beginning and/or adapted over time.

In this case, the respective measuring section 21, 22 may also contain regions of different measurement accuracy, wherein the measurement accuracy may vary discretely and/or continuously over the measuring section 21, 22 or a part of the measuring section 21, 22. Also, the measurement accuracy of the measurement sections 21, 22 may vary over time and/or according to other influences, such as temperature, fouling and/or ageing of the sensors, etc. Thus, the respective weighting factors f1, f2 may comprise geometric factors which are determined by the position of the measured values m1, m2 on the measuring sections 21, 22. For example, the accuracy with respect to the position on the measuring sections 21, 22, the distance to the measuring object, the temperature, stray magnetic fields, etc., may influence the geometry factor. If the accuracy of the measured values m1, m2 decreases towards the edges of the measuring section 21, 22, the geometrical factor can be applied as a function of the distance from the midpoint of the measuring section 21, 22.

Of course, the weighting factors f1, f2 may vary depending on the position of the measured values relative to the measuring sections 21, 22, which may likewise be realized by geometric factors.

The weighting factors f1, f2 may also include statistical factors that are determined by a statistical distribution function. If the probability distributions of the individual measurement segments 21, 22 are known, independently of one another, as standard distributions and with the same mean value, a maximum likelihood estimator using a weighted least squares method can be used. The variance over the measuring sections 21, 22 can be a function of time, but also of the position over the measuring sections 21, 22.

The model factors may also influence the weighting factors f1, f 2. As an example of a model-based estimator, a kalman filter should be mentioned. In designing the kalman filter, assumptions can also be made about the probability distribution of the measured values m1, m 2.

It is also possible to select the first or second measured value m1, m2 itself or the average of the first or second measured values m1, m2 as an approximation of the actual value X. The information mentioned above in the context of the weighting factors affecting the statistical and/or geometrical factors can likewise be used to select the measured values m1, m2 as approximations of the actual value X.

The occurrence of disturbances and/or faults and/or wear on the long stator linear motor 2 can be determined as the operating parameter P from the deviation of the first and second measured values m1, m 2. This is possible if the measured values m1, m2 of the overlapping measuring sections 21, 22 deviate from one another due to interference or failure or wear. Thus, disturbances or faults or wear can be deduced in return. In this case, the type of disturbance, fault or wear can be inferred, for example, on the basis of the magnitude of the deviation. Changing environmental conditions, such as elevated temperature, may also be considered disturbances.