METHOD AND DEVICE FOR MONITORING THE OPERATION OF A TRANSPORTATION EQUIPMENT

Description

Technical field

[0001] The present invention relates generally to the field of plant engineering, in particular to the field of automation technology. Specifically, the present invention relates to a method for monitoring the operation of a transport device in the form of a long-stator linear motor with a transport track along which a plurality of drive coils are arranged. At least one transport unit is moved along the transport track, with drive magnets of the transport unit interacting with the drive coils of the transport track to generate a propulsive force. Furthermore, the invention relates to a device for monitoring the operation of a transport device in the form of a long-stator linear motor. State of the art

[0002] Nowadays, most modern production facilities require the movement of parts or components – sometimes over long distances – between individual handling or production stations using transport equipment. Various transport and conveying systems can be used for this purpose, such as continuous conveyors or conveyor belts in different designs, which convert the rotary motion of an electric drive into linear motion. However, the flexibility of such continuous conveyors is considerably limited; in particular, the individual transport of single units is not possible.

[0003] To meet the requirements of modern and flexible transport systems, so-called long stator linear motors, or LLMs for short, are being used more and more frequently. Long stator linear motors explicitly include both linear motors with movement in one direction and planar motors with movement in one plane, which are often also referred to as planar motors.

[0004] In a linear long-stator linear motor, for example, a multitude of electrical drive coils, forming the stator, are arranged side by side along a transport path or track, usually in a fixed position. A number of drive magnets are arranged on a transport unit. These drive magnets can be either permanent magnets, electrical coils, or short-circuit windings. The drive magnets of the transport unit generate a magnetic excitation field, which interacts with the electromagnetic field of the stator's drive coils. By appropriately controlling the individual drive coils within the transport unit to regulate the magnetic flux, a propulsive force is generated on the transport unit, or its magnitude is influenced, in order to move the transport unit along the transport path as desired.It is also possible to arrange a large number of transport units along the transport path of a linear long-stator linear motor, whose movements can be controlled individually and independently of one another by energizing the drive coils interacting with each transport unit – usually by applying an electrical voltage. Examples of linear long-stator linear motors are known, for example, from WO 2013 / 143783 A1, US 6,876,107 B2, US 2013 / 0074724 A1, and WO 2004 / 103792 A1.

[0005] Planar motors can be used in transport systems, for example, to implement highly flexible transport processes with complex motion profiles. When a planar motor is used in a transport system, a multitude of electrical drive coils, which form the stator, are arranged, for example, in a plane of motion. A magnetic field is generated by the drive coils arranged in this plane of motion, which can be moved in two dimensions (e.g., the xy-plane) within this plane. The drive magnets arranged on the transport unit can also be distributed two-dimensionally to interact with the magnetic field of the drive coils and move the transport unit along a path or transport route defined by the magnetic field within the transport plane. By appropriately arranging the drive coils in the plane of motion and the drive magnets on the respective transport unit, for example,In addition to one-dimensional movement in the transport plane (e.g., along the axes spanned by the transport plane – e.g., the x- and y-axes in an xy-plane), more complex two-dimensional movements in the transport plane are also possible as the path of motion or transport route of a transport unit. The basic operating principle and construction of planar motors are known and can be found, for example, in US 9,202,719 B2 or WO 2021 / 105155 A1.

[0006] Long-stator linear motors can be designed as synchronous machines, either self-excited or separately excited, or as asynchronous machines. A long-stator linear motor is characterized in particular by better and more flexible utilization across the entire operating range of motion (position, speed, acceleration). Furthermore, the transport units are individually controlled along the transport path. Long-stator linear motors also offer improved energy efficiency, reduced maintenance costs due to fewer wear parts, easy replacement of the transport units, efficient monitoring and fault detection, and optimized product flow along the transport path.

[0007] A long-stator linear motor places high demands on the control of the transport unit's movement. This typically requires a multitude of controllers that regulate the current flow to the drive coils to move the transport units along the intended path. Particularly important for the movement of a transport unit in a long-stator linear motor—whether linear or planar—is the interaction between the transport unit's drive magnets and the drive coils that define the transport path. The drive coils and the transport unit are separated by a gap—a so-called air gap. The drive magnets of the transport unit and the drive coils of the transport path are magnetic voltage sources.In addition to magnetic voltage, the interaction between the transport unit and the transport path is also determined by magnetic resistance, which is primarily determined by the air gap, or more specifically, by the size of the gap and the magnetic permeability of the air within it. The magnitude of the magnetic voltages generated by the magnetic voltage sources, as well as the magnitude of the magnetic resistance, directly determine the electromagnetic properties of the long-stator linear motor. The size of the air gap is generally fixed by the design of the long-stator linear motor, for example, by its structural design, and is preferably not changed during operation. The magnetic permeability of the air within the air gap is a constant physical quantity.The magnetic potential of the drive magnets is usually fixed, as they are generally permanent magnets, and remains constant during operation of the transport system. The magnetic potential of the drive coils is defined by the electrical voltage applied to the drive coils, the level of which is usually determined by the control unit of the transport system.

[0008] However, even small changes in the magnetic properties interacting between the drive magnets of the transport unit and the drive coils of the transport track—for example, a change in magnetic resistance due to alterations in the air gap size (e.g., due to wear, varying loads on transport units, faulty guidance of a transport unit, magnet lifting, or assembly errors in the transport unit and / or the transport track)—can affect the operation of the transport system in the form of a long-stator linear motor. Especially in transport systems that consist of multiple transport segments with transfer points (e.g., in the form of switches) for complex and flexible route planning and implementation, malfunctions, particularly at the transfer points, can occur due to changes in the air gap size.

[0009] To ensure the safe operation of transport equipment and, for example, to prevent movements that pose a safety risk, a control system for an electric motor, in particular for a linear motor, is known, for example, from German patent application DE 10 2015 102 236 A1. This system includes a position detection device for recording the positions of the transport units along the stator and a coil monitoring device that generates coil data representing the status of one or more drive coils of the stator. Furthermore, a safety device is provided that compares the position and coil data and, in the event of detected errors in the data comparison, switches the motor to safe operation. This control system can detect errors or malfunctions, such as...Deviating positions of transport units are detected, but changes in the magnetic quantities in the interaction between the drive magnets of the transport unit are not detected by the control system.

[0010] From the publication WO 2019 / 238276 A1, a method for monitoring the wear of a long-stator linear motor and an associated device are known. During operation of the long-stator linear motor, a measuring device is used to measure, for example, a force or differential force exerted by the transport unit on a stator of a motor train or on the transport track, such as a tensile force between a frame and the stator of the transport unit or a compressive force of guide units (e.g., rollers) of the transport units on guide rails. The measured force or differential force is then compared with a permissible maximum value to draw conclusions about the size of the air gap between the stator and the transport unit, in particular a magnet unit on the transport unit. However, such wear monitoring has the disadvantage that additional sensors (e.g.,Measuring cells) must be arranged on the long stator linear motor, whereby the accuracy with which a size of the air gap can be determined depends on the mounting and measuring accuracy of the sensors.

[0011] Alternatively, a method is also known from WO 2019 / 238276 A1 in which a voltage induced by the drive magnets in at least one coil winding of the stator of the long-stator linear motor is measured. This voltage is then used to estimate the size of the air gap. For this purpose, values ​​of a nominally induced voltage for different air gap sizes are calculated from position and speed information of the transport unit as well as the control behavior of the stator control electronics. These calculated values ​​are then compared with the measured induced voltage to determine the actual size of the air gap. In this embodiment, an additional measuring device is also used, which measures the induced voltage in the coil winding. Furthermore, the measurement of the voltage induced in the coil winding can be affected by disturbances (e.g.,Resistance and / or inductance of the coil winding), which can typically change continuously during the operation of the long stator linear motor, can lead to inaccuracies and / or incorrect estimations of the air gap. Description of the invention

[0012] The invention is therefore based on the objective of providing a method and a device with which it is possible to detect assembly errors, signs of wear and / or other malfunctions quickly and with high accuracy during a test operation and / or an ongoing operation of a transport device in the form of a long stator linear motor without great effort.

[0013] This problem is solved by a method and a device for monitoring the operation of a transport device in the form of a long stator linear motor according to the independent claims. Advantageous embodiments of the present invention are described in the dependent claims.

[0014] According to the invention, the problem is solved by a method of the type mentioned above for monitoring the operation of a transport device in the form of a long-stator linear motor, in which at least one drive coil, which is arranged with a plurality of drive coils along a transport path of the transport device, is selected as a measuring coil. Then, during the movement of at least one transport unit along the transport path, a manipulated variable is specified as an excitation signal via the measuring coil, such that the current in the measuring coil is regulated to a predetermined setpoint. Furthermore, while the at least one transport unit is moving over the measuring coil, the temporal profile of the manipulated variable is recorded, and then the recorded temporal profile of the manipulated variable is evaluated for monitoring the transport device.

[0015] The main aspect of the proposed solution is that assembly errors, wear and tear, and / or other malfunctions can be detected quickly and with high accuracy, for example, during a test run and / or during the ongoing operation of the transport system. By evaluating the temporal profile of the manipulated variable, from which the voltage induced in the drive coil (selected as the measuring coil) during the passage of the transport unit can be determined, it is possible, for example, to determine the width of an air gap between the drive coils of the transport track and the drive magnets of the transport unit, and / or the normal force with which the drive magnets of the transport unit act on the surface of the transport track. Furthermore, by comparing this with previously known expected values ​​for the manipulated variable profile, conclusions can then be drawn about wear and tear on the transport unit (e.g.,...).on guide elements, etc.), assembly errors in the transport route (e.g. incorrectly installed drive coils, etc.) and / or the attachment of the drive magnets (e.g. displacement, rotation, detachment, etc.), etc., can be identified or detected very quickly.

[0016] It is advantageous to set the setpoint to which the current in the measuring coil is regulated to a value of zero. With a setpoint of zero, the time course of the voltage induced in the drive coil (selected as the measuring coil) during the movement of the transport unit can be easily determined from the measured time course of the manipulated variable. Ideally, the measured time course of the manipulated variable corresponds to the time course of the induced voltage.

[0017] It is further advantageous if a drive controller, which is assigned to the drive coil selected as a measuring coil, is used as an excitation signal for specifying the manipulated variable. This allows existing hardware of the transport device to be used in a very simple way. The drive controller of the drive coil selected as a measuring coil can, for example, be very easily extended by software for carrying out the method according to the invention and thus be used as a control unit for the method.

[0018] For a transport system with two or more segments, it is advantageous to select at least one drive coil of each segment as a measuring coil. This allows individual segments of the transport system to be easily checked for, for example, assembly errors by selecting appropriate drive coils as measuring coils.

[0019] A preferred embodiment of the invention provides that the at least one drive coil of the transport section, which has been selected as the measuring coil, is selected as such for a limited period. Ideally, the drive coil selected as the measuring coil functions as such only for the duration of one measurement cycle—i.e., for the duration of one passage of a transport unit. This minimizes the time a drive coil is used as a measuring coil. This is particularly advantageous if the coil current is regulated to a predetermined setpoint of zero and the drive coil selected as the measuring coil fails during its use as a measuring coil for a control system to generate a propulsive force. However, it is also possible for a drive coil to function as a measuring coil for, for example, two or more measurement cycles and only then be used solely as a drive coil again.Alternatively, it can also be advantageous if at least one drive coil of the transport section is permanently selected as a measuring coil.

[0020] It is also advantageous to specify an observation period during which the temporal profile of the manipulated variable is recorded. This observation period can range, for example, from a single measurement cycle (i.e., recording the manipulated variable during a passage of the transport unit over the measuring coil) to one or more days and one or more months, up to the entire service life or operating period of the transport system.

[0021] Furthermore, it can be advantageous to record the temporal profile of the manipulated variable at cyclically repeating intervals. The procedure for monitoring the operation of the transport system during the observation period can be repeated, e.g., several times a day, daily, weekly, etc., depending on the application of the transport system, in order to detect wear, errors, etc., very quickly by comparing the recorded temporal profiles of the manipulated variable.

[0022] Ideally, a time-dependent magnetic flux profile is derived from the recorded manifold variable for evaluation purposes. The magnetic flux profile can be derived, for example, by integrating it from the time-dependent voltage induced in the measuring coil, which is derived from the recorded manifold variable. By measuring the magnetic flux profile and comparing it with previously known expected values ​​of characteristic properties (e.g., positions of minima, maxima, and / or zero crossings, amplitude intervals, etc.), information about the drive magnets (e.g., material, strength, polarity, etc.) of the transport unit can be obtained. This information can ideally be used, for example, to select transport units or to detect faulty changes in the drive magnets during operation (e.g.,...Detachment of a magnet, displacement of a magnet, etc.) to detect.

[0023] Furthermore, it is advantageous if the recorded temporal profile of the manipulated variable is normalized to a nominal speed of at least one transport unit. This makes it easier to compare recorded temporal profiles, for example, when changes (e.g., wear, etc.) to the transport unit and / or transport route are to be detected by cyclically repeating the procedure.

[0024] Furthermore, the aforementioned problem is solved by a device for monitoring the operation of a transport system in the form of a long-stator linear motor with a transport section along which a plurality of drive coils are arranged. The transport system also includes at least one transport unit that is movable along the transport section, wherein the drive magnets of the at least one transport unit interact with the drive coils of the transport section to generate a propulsive force. This device includes at least one measuring coil, which can be selected from the plurality of drive coils arranged along the transport section, and a control unit configured to provide the measuring coil with a manipulated variable as an excitation signal such that the current in the measuring coil is regulated to a predetermined setpoint.Furthermore, the device has a unit for recording the temporal profile of the manipulated variable and a unit for evaluating the recorded temporal profile of the manipulated variable.

[0025] A dedicated controller can be used as the control unit. Ideally, however, a drive controller assigned to the drive coil selected as the measuring coil can be used as the control unit. This easily avoids the need for an additional hardware unit in the transport system.

[0026] Ideally, to further reduce hardware requirements, the unit for capturing the temporal profile of the manipulated variable can also be integrated into the control unit – specifically, into the drive controller of the drive coil selected as the measuring coil. This allows the control unit to regulate the coil current in the measuring coil to the specified setpoint and simultaneously capture the temporal profile of the manipulated variable during control for evaluation purposes, all without the need for additional equipment.

[0027] Furthermore, it is advantageous if the unit for evaluating the time course of the manipulated variable is configured to derive a time course of magnetic flux from the detected manifold. Ideally, a time course of the voltage induced in the drive coil selected as the measuring coil can be determined from the detected time course of the manipulated variable by the unit for detecting the time course of the manipulated variable or by the unit for evaluating the time course of the manipulated variable. Brief description of the drawings

[0028] The present invention is described below with reference to the Figures 1 to 5a or 5b, which show exemplary, schematic and non-restrictive advantageous embodiments of the invention. In doing so, it shows Fig. 1 a design of a transport device in the form of a long stator linear motor, Fig. 2a detailed view of the structure of a transport segment and a transport unit, Fig. 3 a variant of the method for monitoring the operation of a transport system with an associated device Fig. 4 a simplified equivalent circuit diagram of the measuring coil Fig. 5a a temporal progression of a recorded control variable as a function of a position of the transport unit, Fig. 5b a time course of a magnetic flux as a function of the position of the transport unit. Implementation of the invention

[0029] In Figure 1A transport device 1 in the form of a long-stator linear motor, for example a linear long-stator linear motor, is shown as an example. The transport device 1 consists of a number of transport segments TSk (k≥1 is an index representing all existing transport segments TS1, TS2, TS3, ..., TS7), of which, for the sake of clarity, only transport segments TS1, ..., TS7 are shown as examples. Each transport segment TSk is arranged on one side of the transport track 2 – for example, on a support structure (not shown). The transport segments TSk form various sections of the transport track 2, such as straight lines, curves with different angles and radii, switches, etc., and can be flexibly assembled to form the transport track 2.

[0030] The transport segments TSk together form the mostly stationary transport route 2, along which the transport units Tn (n≥1 is an index that stands for all existing transport units T1, T2, T3, T4, ..., whereby for the sake of clarity not all transport units Tn are shown in the Figure 1 (marked with reference symbols) can be moved. Due to such a modular design, the transport device 1 or the transport track 2 can be designed very flexibly, but also requires a large number of transfer positions U, such as switches, etc., at which the transport units Tn moved on the transport device 1 are transferred from one transport segment TSk to another.

[0031] The transport device 1 is designed as a long-stator linear motor, in which the transport segments TSk each form a part of a long stator of the long-stator linear motor in a manner known per se. Along the transport segments TSk, a plurality of stationary electrical drive coils 3 forming the stator are therefore arranged longitudinally in a known manner (in Fig. 1 (For the sake of clarity, only the transport segments TS1, TS2, TS4, TS5, TS6, TS7 are indicated).

[0032] The drive coils 3 can be connected to drive magnets 4 on the transport units T1, ..., Tn (in Fig. 1 (For the sake of clarity, only shown for transport unit T6) to generate a propulsive force Fv. The drive coils 3 are controlled in a well-known manner by a control unit or a drive controller 5 (in Fig. 1(only indicated), in order to apply the coil voltages required for the desired movement of the transport units Tn.

[0033] There may also be sections along transport route 2, such as transfer positions U, etc., where transport segments TSk are arranged on both sides, between which a transport unit Tn moves (for example, transport segments TS1, TS4). If the transport unit Tn is equipped with drive magnets 4 on both sides (viewed in the direction of movement), then the transport unit Tn can also interact simultaneously with the transport segments TSk arranged on both sides or with their drive coils 3. This, of course, allows a greater overall propulsive force FV to be generated.

[0034] A transport device 1 in the form of a planar motor has a transport plane as its transport area, in which a plurality of drive coils 3 are arranged. In normal operation, the drive coils 3 are controlled, for example, in a well-known manner by a control unit or a drive controller 5, in order to generate a magnetic field in the transport plane and to move the transport units Tn in the transport plane, e.g., along a desired path. By appropriately controlling the drive coils 3, one or more transport units Tn can also be moved along more complex paths, which are not necessarily only parallel to one of the axes of the planar motor's transport plane. Furthermore, in a transport device 1 in the form of a planar motor, the transport plane can be arbitrarily shaped or guided in space, depending on the application and requirements.Furthermore, the transport level and thus the possible movement paths or transport routes 2 of the transport units Tn often consist of several transport segments TSk arranged next to each other.

[0035] Figure 2 Figure 1 shows in detail the structure of an exemplary transport segment TSk of transport route 2 and an exemplary transport unit Tn, which moves along the transport segment TSk. The transport unit Tn has, for example, a base body 6 to which a carrier or magnetic plate 7 is attached. The drive magnets 4 are arranged on the magnetic plate 7. A drive magnet 4 can be designed as an electromagnet (excitation coils) and / or as a permanent magnet. In the Figure 2 In the transport unit Tn shown as an example, the drive magnets 4 are designed as permanent magnets and are arranged on the magnetic plate 7 with alternating polarity.

[0036] In a transport unit Tn designed for use with a linear long-stator linear motor, guide elements such as rollers, wheels, sliding surfaces, guide magnets, etc., can of course also be provided on the transport unit Tn to guide and hold the transport unit Tn along the transport path 2, especially when stationary. The guide elements of the transport unit Tn interact with the transport path 2 or the transport segments TSk for guidance, e.g., by the guide elements bearing against, hooking onto, sliding or rolling along the transport path 2, etc.

[0037] Along the transport segment TSk, the drive coils 3 are arranged – preferably on teeth 8 of a ferromagnetic core (for example, an iron core stack). The drive coils 3 can, of course, also be coreless. A magnetic excitation field is generated by the drive magnets 4 of the transport unit Tn, which interacts with the electromagnetic field of the drive coils 3 of the transport segment TSk. By applying a corresponding current to the individual drive coils 3 in the area of ​​the transport unit Tn, the propulsive force Fv is generated or its magnitude is influenced. This moves the transport unit Tn along the transport segment TSk or along the transport path 2 in a desired direction of movement B at a velocity v. An air gap 9 with an air gap width or size L is formed between the drive coils 3 of the transport segment TSk and the drive magnets 4 of the transport unit Tn.

[0038] To monitor the operation of the transport device 1, at least one of the drive coils 3 can now be selected in a selection step S1, which is then used as a measuring coil M for monitoring. For transport devices 1 with at least two or more transport segments TSk, for example, at least one drive coil 3 can be designated as a measuring coil M in each transport segment TSk. Alternatively, it is also possible to select at least one drive coil 3 only in selected transport segments TSk, which, for example, are to be checked or monitored during the operation of the transport device 1. This drive coil then functions as a measuring coil M. Furthermore, it is possible to select or use several drive coils 3 as measuring coils M simultaneously in a transport segment TSk, whereby the drive coils 3 selected as measuring coils M should be spatially separated from one another.

[0039] Typically, a drive coil 3 selected as a measuring coil M functions as such only for a limited time, for example, for one measurement cycle or for one passage of a transport unit Tn. Afterwards, the measuring coil M is used again only as a drive coil 3. However, it is also possible that at least one drive coil 3 is selected as a measuring coil M, for example, for two or more measurement cycles or passages of transport units Tn, or permanently.

[0040] In Figure 3An exemplary and schematic device for monitoring the operation of the transport device 1, as well as an exemplary sequence of a method for monitoring the operation of the transport device 1, are shown. The device comprises at least one control unit RE, a measuring coil M which forms a controlled system RS, a unit EE for recording the temporal profile of a manipulated variable SG, which is output by the control unit RE, and an evaluation unit AW for evaluating the recorded temporal profile of the manipulated variable SG.

[0041] For monitoring transport equipment 1 – e.g., during the ongoing operation of transport equipment 1 or during a test phase of transport equipment 1 – selection step S1 is used – as already described in Figure 2As shown, at least one drive coil 3 is selected, which functions as a measuring coil M for monitoring the transport device 1. Typically, the drive coil 3 is selected as measuring coil M only for the duration of a measurement cycle – i.e., for example, the duration of one run of the procedure for monitoring the transport device 1 or the duration of a passage of a transport unit Tn. For a further or subsequent measurement cycle, at least one other drive coil 3 of the transport track 2 or of a respective transport segment TSk can be used as measuring coil M. Alternatively, at least one drive coil 3 of the transport device 1 or of a transport segment TSk can be designated as measuring coil M for two or more measurement cycles or permanently.

[0042] During movement or passage of the transport unit Tn over the measuring coil M, a manipulated variable SG, e.g., a control voltage u ph, is applied to the measuring coil M as a controlled system RS in a control step S2. The application of the manipulated variable SG establishes a controlled current, and the current coil current i ph is regulated to a predetermined setpoint i 'target'. For this purpose, the current coil current i ph in the measuring coil M is determined and fed back to an input of the control unit RE. The currently determined coil current i ph is compared with the predetermined setpoint i 'target', and the difference between the current coil current i ph and the setpoint i 'target' is fed to the control unit RE to determine the manipulated variable SG or the control voltage u ph as a drive signal. The control unit RE then applies the corresponding manipulated variable SG or control voltage u ph to the measuring coil M.A corresponding control current is then established, thereby regulating the coil current i ph to the specified setpoint i soll. For example, a setpoint of zero can be specified as i soll, in which case the drive coil 3, selected as the measuring coil M, no longer participates in the control for generating the propulsive force Fv.

[0043] As the transport unit Tn passes over the measuring coil M, the drive magnets 4 of the transport unit Tn are moved across the measuring coil M, thereby inducing a voltage u emk in the measuring coil M due to the drive magnets 4. If, for example, a setpoint i soll of zero is specified for the current coil current i ph, then during control step S2, i.e., during the passage of the transport unit Tn over the measuring coil M, the current coil current i ph can only develop if there is a difference between the voltage u emk induced in the measuring coil M and the manipulated variable SG or manipulated voltage u ph specified as the excitation signal for the measuring coil M. If the manipulated variable SG or the manipulated voltage u ph corresponds to the voltage u emk induced in the measuring coil M during the passage of the transport unit Tn, then, for example, a coil current i ph with the specified setpoint i soll of zero flows in the measuring coil M. That is to sayNo coil current i ph can flow in the measuring coil M. In control step S2, the manipulated variable SG is therefore set for the measuring coil M such that the current coil current i ph in the measuring coil M is regulated to the specified setpoint i soll – e.g., to zero. The drive coil 3, selected as measuring coil M, can therefore no longer be used for controlling the propulsive force Fv when the setpoint i soll is zero while functioning as measuring coil M.

[0044] If, for example, an arbitrary setpoint ishall (i.e., non-zero) is specified for controlling the current iph in the measuring coil, a voltage drop across the measuring coil M must be taken into account. This drop is caused by the resistive component Rph and the inductance Lph of the measuring coil M, as well as by the coil current iph. However, controlling the coil current iph in the measuring coil M to an arbitrary setpoint ishall has the advantage that the drive coil 3, selected as the measuring coil M, can also be used as the drive coil 3 – i.e., it participates in the control for generating the propulsive force Fv.

[0045] For example, an existing drive controller 5, which is assigned to the measuring coil M, can be used as the control unit RE. The drive controller 5 of the measuring coil M can be extended, for example, by a suitable control component. Alternatively, the control unit RE can also be provided as an additional controller RE with a corresponding transfer function.

[0046] For the design of the control unit RE, by which the coil current i ph in the measuring coil M is regulated to the specified setpoint i soll (e.g., the value zero) during the passage of the transport unit Tn, a simplified equivalent circuit diagram of the measuring coil M can be used, for example. From this simplified equivalent circuit diagram, which is in Figure 4 The transfer function of the control unit RE can be derived from the diagram.

[0047] The equivalent circuit of the measuring coil M, for example, has a resistive component Rph and an inductance Lph. The movement of the transport unit Tn induces the voltage uemk in the measuring coil M, which is represented as the voltage source uemk. A further voltage drop occurs between the terminals of the equivalent circuit, corresponding to the manipulated variable SG output by the control unit RE. If there is a voltage difference between the induced voltage uemk and the manipulated voltage uph, the coil current iph flows in the measuring coil M, causing a voltage drop across the measuring coil M – across the resistive component Rph and the inductance Lph. The relationship can be described, for example, as follows: u emk = u ph − R ph * i ph − L ph * di ph / dt .

[0048] From this context, it is evident that for regulating the coil current iph to the specified setpoint isol (e.g., the value of zero), the manipulated variable SG or the manipulated voltage uph corresponds to the voltage uemk induced in the measuring coil M – possibly taking into account the voltage drop across the measuring coil M. That is, if, for example, the induced voltage uemk and the manipulated voltage uph are equal, no current iph will flow through the measuring coil M. Thus, from the in Figure 4 Derive the transfer function for the control unit RE from the exemplary equivalent circuit diagram shown.

[0049] For the controlled system RS or the measuring coil M, the following transfer function F(s) results in the so-called Laplace domain, on the basis of which, for example, the control unit can then be designed: F s = iph uph = 1 Rph + s ∗ Lph

[0050] Here, F(s) represents a Laplace transform of a function f(t). The so-called Laplace transform transforms a given function f(t) in the real time domain into a function F(s) in a complex spectral domain (e.g., the frequency domain).

[0051] The voltage u emk induced in the measuring coil M during the passage of the transport unit Tn can, for example, be - as in Figure 3 The disturbance variable u emk is represented and interpreted as acting at an input of the measuring coil M or the controlled system RS. During control, this disturbance variable u emk must be (additionally) provided by the control unit RE.

[0052] Alternatively, the induced voltage uemk or the disturbance uemk can be compensated, for example, by means of feedforward control. For this purpose, the manipulated variable SG is supplied with expected values ​​of the induced voltage uemk, which are estimated, for example, based on the speed of the transport units Tn using dynamic mathematical models. Ideally, the optional feedforward control, which can be integrated into the control unit RE, relieves the control unit RE of some of its workload.

[0053] In acquisition step S3, the temporal profile of the manipulated variable SG output by the control unit RE is recorded as long as the transport unit Tn moves over the measuring coil M. The manipulated variable SG corresponds to the control voltage u ph, which is applied to the measuring coil M as an excitation signal. The coil current i ph is continuously regulated by the control unit RE to the predefined setpoint i soll (e.g., zero) during the movement of the transport unit Tn over the measuring coil M, and the temporal profile of the manipulated variable SG output by the control unit RE, or the control voltage u ph, is recorded. The temporal profile of the manipulated variable SG can be recorded, for example, using the unit EE for capturing the temporal profile of the manipulated variable SG. This unit EE can be implemented as a separate unit or integrated into the control unit RE.

[0054] From the recorded temporal profile of the manipulated variable SG or the manipulated voltage u ph output by the control unit RE, the temporal profile of the voltage u emk induced in the measuring coil M by the drive magnets 4 of the transport unit Tn can be determined. For example, with a given setpoint i, the temporal profile of the manipulated variable SG or the manipulated voltage u ph output by the control unit RE corresponds to the temporal profile of the voltage u emk induced in the measuring coil M by the drive magnets 4 of the transport unit Tn.

[0055] For a given setpoint i, the voltage drop across the measuring coil M caused by the coil current i ph must be considered in order to determine the time course of the induced voltage u emk from the measured time course of the manipulated variable SG or the manipulated voltage u ph. For this purpose, for example, drive coils 3 of the transport section 2 can be measured once beforehand, whereby the voltage drop across at least one drive coil 3 selected as a measuring coil M for the given setpoint i is determined by measurement, or the voltage drop for the given setpoint i is modeled – for example, using a model for the coil 3 with, for example, at least one resistive component R ph and an inductance L ph.

[0056] In evaluation step S4, the recorded temporal profile of the manipulated variable SG is evaluated for monitoring the transport unit Tn. The acquisition step S3 and the evaluation step S4 can, for example, largely run in parallel. This means that in evaluation step S4, for instance, the first recorded values ​​of the manipulated variable SG output by the control unit RE can already be evaluated, while the transport unit Tn continues to move over the measuring coil M, and further values ​​for the temporal profile of the manipulated variable SG are recorded in acquisition step S3.

[0057] In evaluation step S4, for example, an evaluation unit AW can be used to evaluate the temporal profile of the manipulated variable SG. From the recorded temporal profile of the manipulated variable SG, or from the temporal profile of the induced voltage u emk determined from it, conclusions can be drawn about the properties of the drive magnets 4 or the air gap 9, such as the air gap width L. Furthermore, it is possible to infer a normal force exerted by the drive magnets 4 of the transport unit Tn on a surface of the transport track TSk from characteristics (e.g., minima, maxima, root mean square, etc.) of the profile of the induced voltage u emk. Evaluation options will be described in more detail below. Figure 5a explained in more detail.

[0058] From the recorded manifold variable SG, a magnetic flux profile ψ can also be derived, which is responsible for the voltage u emk induced in the measuring coil M. The derivation and evaluation of the time-dependent magnetic flux ψ can also be performed in evaluation step S4 within the evaluation unit AW to evaluate the time-dependent manifold variable SG. For this purpose, the profile of the induced voltage u emk, which was determined from the recorded manifold variable profile, can be integrated. Evaluation options for the time-dependent magnetic flux ψ will be discussed further below. Figure 5b explained in more detail.

[0059] Furthermore, the time course of the manipulated variable SG in evaluation step S4 can be normalized again by the evaluation unit AW to a nominal speed (e.g. 1 m / s) of the transport unit Tn for the purpose of evaluating the time course of the manipulated variable SG.

[0060] Figure 5a Figure 1 shows an example of a recorded, time-dependent behavior of the manipulated variable SG, where the coil current iph was regulated to a predetermined setpoint isollen of zero. Thus, the time-dependent behavior of the manipulated variable SG also corresponds to the time-dependent behavior of the voltage uemk induced in the measuring coil M while the transport unit Tn is moved over the measuring coil M. The x-axis represents the respective position of the transport unit Tn in meters above the selected measuring coil M. The y-axis shows a corresponding value of the manipulated variable SG or the control voltage uph, and thus the voltage uemk induced in the measuring coil M during the regulation of the coil current iph to the predetermined setpoint isollen or to the value zero. The manipulated variable SG, the control voltage uph, and the voltage uemk induced in the measuring coil M are plotted in volts. From the in Figure 5aThe depicted sequence shows that at the first position P1 of the transport unit Tn, a first drive magnet 4 of the transport unit Tn is initially aligned with the measuring coil M. At the first position P1, the induced voltage u emk and thus the manipulated variable SG begin to increase, since from the first position P1 onwards, the control unit RE begins to regulate the coil current i ph to the setpoint i soll or to zero. The subsequent course of the induced voltage u emk and the manipulated variable SG shows how these increase or decrease and assume positive or negative extreme values, depending on how many and which drive magnets 4 of the transport unit Tn, with their respective polarities, interact with the measuring coil M at the respective position that the transport unit Tn assumes during its movement.At a second position P2 of the transport unit Tn, the area of ​​the measuring coil M is left by the last drive magnet 4 of the transport unit Tn. The induced voltage u emk or the manipulated variable SG then drops back to a voltage value of zero.

[0061] From the in Figure 5aThe exemplary curve of the manipulated variable SG or the voltage u emk induced in the measuring coil M allows properties of the transport device 1, in particular properties of the drive magnets 4 of the respective transport unit Tn, to be derived, e.g., during operation, during a specified observation period, or during a test phase, etc. Above all, the characteristics of the measured, induced voltage u emk, such as minima, maxima, root mean square, etc., allow conclusions to be drawn about the normal force with which the drive magnets 4 act on the surface of the transport track 2 or the respective transport segment TSk.

[0062] For example, the manipulated variable SG or the induced voltage u emk can be repeatedly recorded using a test transport unit Tn. For instance, the air gap 9 or the size L of the air gap 9 between the drive magnets 4 and the surface of the transport track 2 is adjusted for each measurement of the manipulated variable SG. This means that several profiles of the manipulated variable SG or the induced voltage u emk are determined with different air gap widths L. For these profiles, characteristic values ​​such as minima, maxima, and root mean squares can then be determined in evaluation step S4. If the test transport unit Tn is also measured once beforehand with an external measuring system with regard to the normal force, a characteristic curve for the normal force can be determined as a function of the characteristic values ​​of the induced voltage u emk.Given the known magnetic properties of the drive magnets 4 of the respective transport unit Tn, it is further possible to deduce the air gap 9 of the respective transport unit Tn (e.g. width of the air gap 9, etc.) based on this characteristic curve.

[0063] Furthermore, assuming that the air gap 9 between the transport unit Tn and the surface of the transport track 2 remains constant during a predetermined observation period, temperature changes in the area of ​​the inducing drive magnets 4 on the transport unit Tn can be inferred using the method according to the invention. For this purpose, for example, a short observation period (e.g., one or a few days, etc.) is selected, during which the course of the manipulated variable SG or the induced voltage u emk is repeatedly recorded.

[0064] For wear analysis (e.g., wear of guide elements on transport units Tn, etc.), a longer observation period, such as one or more months, can be specified, during which the course of the manipulated variable SG or the induced stress u emk is repeatedly determined. From this, the normal force and / or the air gap 9 are then derived and recorded. The recording of the manipulated variable SG course within the respective observation period can be performed continuously or cyclically at predetermined intervals (e.g., daily, weekly, etc.).

[0065] For example, during operation of a transport device 1, the inventive method for monitoring the operation of a transport device 1 can be repeatedly carried out for selected transport units Tn over a predetermined observation period (e.g., several days or several months). This means that the course of the manipulated variable SG or the induced voltage u emk at at least one selected measuring coil M is recorded for each of the selected transport units Tn, and from this, for example, a course of the respective normal force with which the drive magnets 4 of the respective transport unit Tn act on the surface of the transport track is determined. Changes in the determined courses can, for example, indicate wear of the guide elements of the respective transport unit Tn. Furthermore, the change in the normal force can also, for example, indicate the temperature of the drive magnets 4.

[0066] From a time course of the manipulated variable SG - as exemplified in Figure 5a As shown, for example, a time course of the magnetic flux ψ as a function of a position P of the transport unit Tn as it passes over the measuring coil M can be derived by means of integration. Such a course is exemplified in Figure 5bThe graph shows the position P of the transport unit Tn in meters above the selected measuring coil M. The corresponding value of the magnetic flux ψ is plotted on the y-axis. Depending on the position P of the transport unit Tn and the interaction of one or more drive magnets 4 with the measuring coil M, and depending on the respective polarity of the acting drive magnets 4, extreme values ​​(minima, maxima) and zero crossings occur over time in the magnetic flux ψ. If these extreme values ​​(height, position, amplitude, etc.) are evaluated, conclusions can be drawn, for example, about the material used for the drive magnets 4, their application (e.g., bonding, etc.), etc. Thus, extreme values ​​such as the amplitude of the negative maxima, which, for example, correspond to one of the polarities of the drive magnets 4, or the amplitudes of the edge maxima, which, for example, correspond to the effect of the respective edge drive magnets, etc., can be used to determine the magnetic flux ψ.The measured values ​​can be compared with expected values. Furthermore, the distances between the extreme values ​​in the course of the magnetic flux ψ can also be evaluated and compared with corresponding expected values. In this way, errors in the mounting of the drive magnets 4 on the transport unit Tn – such as magnet detachments, displacement of magnets 4, rotations in the polarity direction, etc. – can be detected. Furthermore, based on the evaluation of the extreme values ​​of the time course of the magnetic flux ψ, a selection can also be made for transport units Tn for the ongoing operation of the transport device 1.

[0067] Furthermore, the method for monitoring a transport device 1 with the associated apparatus also offers the possibility of checking the settings of transport segments TSk of the transport track 2, in particular the setting of the transport segments TSk in the guidance system. For this purpose, for example, at least one drive coil 3 can first be selected as a measuring coil M in each transport segment TSk to be tested. A defined transport unit Tn is then positioned on the transport device 1 or on the transport track 2, for which, for example, the time course of the manipulated variable SG or the normal force is known. The transport unit Tn is then moved along the transport track 2 or over the transport segments TSk to be tested, and the time course of the manipulated variable SG is recorded, and, for example, the normal force is derived accordingly. This process is repeated for each additional drive coil 3 of the respective transport segment TSk to be tested – i.e.,Each drive coil 3 of the transport segment TSk under test functions as a measuring coil M for at least one measurement cycle of the manipulated variable SG. Subsequent evaluation of the recorded time-dependent profiles of the manipulated variable SG for the drive coils 3 of the respective transport segment TSk provides an overview of, for example, the normal force and / or air gap 9 of the respective inspected transport segment TSk of the transport route 2. This allows, for example, the detection and correction of poorly or incorrectly installed transport segments TSk, drive coils 3, etc. Reference symbol list

[0068] Figure 1 1 Transport device 2 Transport track TS1, ..., TSk Transport segment U Transfer positions T1, ..., Tn Transport unit 3 Drive coils 4 Drive magnets Fv Propulsion force 5 Drive controller Figure 26 Base body of the transport unit 7 Carrier plate 8 Teeth 9 Air gap B Direction of movement of the transport unit v Speed ​​of the transport unit L Air gap width M Measuring coil Figure 3 i ph coil current ME measuring unit i setpoint RE control unit RS controlled system SG manipulated variable u emk induced voltage by a transport unit Tn EE unit for acquiring the manipulated variable AW evaluation unit for evaluating the acquired manipulated variable S1 selection step S2 control step S3 acquisition step S4 evaluation step Figure 4 R ph ohmic component of the measuring coil L ph inductance of the measuring coil u ph voltage across the measuring coil Figures 5a and 5b P Position of the transport unit P1 First position of the transport unit P2 Second position of the transport unit ψ Magnetic flux

Claims

1. A method for monitoring the operation of a transport device (1) in the form of a long stator linear motor having a transport track (2) along which a plurality of drive coils (3) are arranged, and wherein at least one transport unit (Tn) is moved along the transport track (2), wherein drive magnets (4) of the transport unit (Tn) interact with the drive coils (3) of the transport track (2) to produce a propulsive force (Fv), characterized in that at least one drive coil (3) of the transport track (2) is selected (S1) as a measurement coil (M), in that, while the at least one transport unit (Tn) is moving over the measurement coil (M), a manipulated variable (SG) is predetermined (S2) as an excitation signal in a such way that a respective present coil current (iph) in the measurement coil (M) is controlled to a predetermined setpoint value (isoll), in that a time profile of the manipulated variable (SG) is captured (S3), while the at least one transport unit (Tn) is being moved over the measurement coil (M), and in that the captured time profile of the manipulated variable (SG) is evaluated (S4) to monitor the transport device (1).

2. The method as claimed in claim 1, characterized in that a value of zero is specified (S2) as the setpoint value (isoll).

3. The method as claimed in claim 1 or 2, characterized in that a drive controller, which is assigned to the drive coil (3) selected as the measurement coil (M), is used for predetermining the manipulated variable (SG) as the excitation signal (S2).

4. The method as claimed in one of the preceding claims, characterized in that, in the case of a transport track (2) with at least two transport segments (TSk), at least one drive coil (3) is selected (S1) as the measurement coil (M) in each transport segment (TSk).

5. The method as claimed in one of the preceding claims, characterized in that the at least one drive coil (3) of the transport track (2) is selected (S1) as the measurement coil (M) for a limited time, in particular for a duration of one measurement cycle.

6. The method as claimed in one of claims 1 to 4, characterized in that the at least one drive coil (3) of the transport track (2) is selected (S1) as the measurement coil (M) permanently.

7. The method as claimed in one of the preceding claims, characterized in that an observation period, in which the time profile of the manipulated variable (SG) is captured (S3), is specified.

8. The method as claimed in one of the preceding claims, characterized in that the time profile of the manipulated variable (SG) is captured (S3) at cyclically repeating intervals.

9. The method as claimed in one of the preceding claims, characterized in that a time profile of a magnetic flux (ψ) is derived (S4) from the captured time profile of the manipulated variable (SG) for evaluation.

10. The method as claimed in one of the preceding claims, characterized in that the captured time profile of the manipulated variable (SG) is normalized (S4) to a nominal speed of the at least one transport unit.

11. An apparatus for monitoring the operation of a transport device (1) in the form of a long stator linear motor having a transport track (2) along which a plurality of drive coils (3) are arranged, and having at least one transport unit (Tn) which is able to be moved along the transport track (2), wherein drive magnets (4) of the transport unit (Tn) interact with the drive coils (3) of the transport track (2) to produce a propulsive force (Fv), characterized in that the apparatus at least comprises: - a measurement coil (M) being selected from the plurality of drive coils (3) arranged along the transport track (2); - a control unit (RE) which is configured to predetermine a manipulated variable (SG) as an excitation signal to the measurement coil (M) in such a way that the respective present coil current (iph) is controlled to a specified setpoint value (isoll); - a unit (EE) for capturing a time profile of the manipulated variable (SG); and - an evaluation unit (AW) for evaluating the time profile of the manipulated variable (SG).

12. The apparatus as claimed in claim 11, characterized in that a drive controller (5), which is assigned to the drive coil (3) selected as the measurement coil (M), is used as the control unit (RE).

13. The apparatus as claimed in one of claims 11 to 12, characterized in that the unit (EE) for capturing the time profile of the manipulated variable (SG) is integrated into the control unit (RE).

14. The apparatus as claimed in one of claims 11 to 13, characterized in that the evaluation unit (AW) for evaluating the time profile of the manipulated variable (SG) is configured to derive a time profile of a magnetic flux (ψ) from the captured profile of the manipulated variable (SG).