Method for operating a fluid system, fluid system and computer program product

Abstract

The invention relates to a method for operating a fluid system, the method comprising the following steps: receiving or determining a setpoint valve stroke, determining an actual valve stroke based on a sensor signal of a position sensor (46), determining a deviation value of a working valve (11) depending on sensor signals of a supply pressure sensor (40), a working pressure sensor (41), a position sensor (46) and a sensor device (44), and processing the setpoint valve stroke, the actual valve stroke and the deviation value into a control signal for actuating the working valve (11).

Description

Technical Field

[0001] The invention relates to a method for operating a fluid system. Furthermore, the invention relates to a fluid system and a computer program product. Summary of the invention

[0002] The object of the present invention is to specify a method, a fluid system and a computer program product for operating a fluid system, by means of which time-dependent and / or operation-type-dependent changes of a working valve of which the working valve is a component can be taken into account during the operation of the fluid system.

[0003] According to a first inventive aspect, this object is achieved by a method for operating a fluid system according to claim 1 .

[0004] Here, the fluid system comprises a control device and a working valve that can be controlled by the control device, the working valve comprising an input connection, to which a fluid source and a supply pressure sensor are connected, and the working valve comprising an output connection, to which a fluid consumer and a working pressure sensor are connected, and the output connection is assigned a position sensor for detecting a valve position, wherein the fluid consumer is assigned a sensor device for detecting a movement state, and wherein the supply pressure sensor, the working pressure sensor and the sensor device are connected to the control device. To perform the method, the following steps are performed: receiving or determining a setpoint valve stroke, determining an actual valve stroke based on a sensor signal of the position sensor, determining a deviation value of the working valve depending on the sensor signals of the supply pressure sensor, the working pressure sensor, the position sensor and the sensor device, and performing processing of the setpoint valve stroke, the actual valve stroke and the deviation value into a control signal for controlling the working valve.

[0005] The purpose of the method is to take into account changes in the characteristics of the working valve for the control of the working valve, which can be expressed as deviation values, so that precise control of the working valve can always be ensured, especially with respect to the opening characteristics of the working valve. The changes in the characteristics of the working valve can depend on the duration of use of the working valve on the one hand and on the other hand on the operating conditions for the use of the working valve. The changes are caused in particular by the properties of at least one sealing portion arranged in the working valve, which should, together with the valve unit movably accommodated in the working valve, promote a sealing effect between the input connection and the output connection of the working valve in the first functional position. Usually, the sealing portion is made of an elastic material, in particular a rubber-elastic material, which, due to the length of the use period, the number of switching operations for the working valve, the properties of the fluid flowing through the working valve and the ambient conditions in which the working valve is used, can also undergo plastic (irreversible) deformation in addition to elastic (reversible) deformation when the valve unit is in contact. Due to the plastic deformation, the opening position for the working valve, that is to say the position of the valve unit, in which a fluid flow occurs at a given pressure difference between the inlet and outlet connections, changes. Since the opening position is decisive for almost the entire operating range of the working valve, correctly determining and taking into account the deviation value of the working valve enables particularly precise operation of the working valve.

[0006] The execution of the method is basically carried out by a control mechanism, which is configured to provide a control signal to the working valve. The control mechanism can be constructed, for example, in a valve island (Ventilinsel) and includes, for example, a signal processing mechanism for processing sensor signals and a microprocessor as important components. In particular, the signals of the supply pressure sensor, the working pressure sensor, the position sensor and the sensor mechanism are regarded as sensor signals. In addition, purely exemplary, the control mechanism includes at least one (electrical or electronic) final stage (Endstufe, which can also be translated as an output stage), which can output a control signal suitable for controlling the working valve. For example, it is set that the working valve is constructed as a solenoid valve or as a valve pre-controlled by fluid. In the design scheme of the working valve as a solenoid valve, the coil current is provided by the final stage of the control mechanism for controlling the solenoid coil constructed in the working valve, so as to cause a position change of the valve unit constructed in the working valve. In the design scheme of the working valve as a valve pre-controlled by fluid, it can be set that the control mechanism has two final stages, and the two final stages are respectively constructed as pre-control valves for controlling electronic machinery, especially solenoid valves or piezoelectric valves. The two pilot control valves are themselves designed to supply working fluid to or remove working fluid from the working valve in order to bring about a movement of a valve unit of the working valve and thereby influence a pilot value for the working valve.

[0007] The working valve has a valve housing through which a fluid channel passes, the fluid channel extending between an inlet connection and an outlet connection and accommodating a valve seat and a valve unit arranged so as to be movable relative to the valve seat. A sealing part is associated with the valve seat, the sealing part is made of an elastic, in particular rubber-elastic material and in cooperation with the valve unit, the sealing part brings about a sealing closure of the fluid channel in the closed position of the working valve.

[0008] A supply pressure sensor is arranged at the input connection of the working valve, which can be optionally integrated in the working valve or can be assigned to the working connection as a separate assembly. In the same way, a working pressure sensor is arranged at the output connection of the working valve, which can also be optionally integrated in the working valve or can be assigned to the working connection as a separate assembly. Not only the supply pressure sensor but also the working pressure sensor is configured to provide an analog or digital sensor signal and is connected to the control mechanism. In addition, the working valve is equipped with a position sensor, which can be configured in the type of a stroke measurement system and is used to detect the actual valve stroke of the working valve. The position sensor is also configured to provide an analog or digital sensor signal and is connected to the control mechanism.

[0009] In addition, it is provided that the fluid consumer is provided with a sensor device, which is configured to detect the movement state of the fluid consumer. For example, the fluid consumer connected to the output connection of the working valve is configured as a pneumatic cylinder, as a pneumatic motor, as a pneumatic swivel drive, or as a volume to be filled with compressed air or protective gas or to be evacuated, in particular as a packaging bag. With the help of the sensor device, for example, the movement speed of a moving component of the fluid consumer, for example, a working piston, a rotor or a swivel piston can be detected and the movement speed can be provided to the control device as an analog or digital sensor signal. In addition, at least in the design of the fluid consumer as a pneumatic cylinder or as a swivel drive, the position of the working piston or the swivel piston can be determined with the help of the sensor device and transmitted to the control device as a sensor signal.

[0010] The desired valve stroke required within the scope of the method can optionally be ascertained in the control device as a function of incoming sensor signals, in particular sensor signals of a sensor device of a fluid consumer, or can be transmitted to the control device from an external component, such as a machine control.

[0011] The actual valve travel required within the scope of execution of the method is ascertained as a function of the sensor signal of the position sensor.

[0012] By way of example, it is provided that the theoretical valve stroke and the actual valve stroke are processed in the range of making a difference in the regulating algorithm running in the control mechanism, so as to thereby obtain a temporary control signal. The temporary control signal can be used to control the working valve, wherein the temporary control signal does not take into account the deviation value of the working valve and thus may lead to inaccurate control of the working valve in the case of changes in the valve characteristics of the working valve due to aging and / or due to the type of operation. Accordingly, it is provided that the temporary control signal is combined with the deviation value, which is obtained in the control mechanism based on the sensor signals of the supply pressure sensor, the working pressure sensor, the position sensor and the sensor mechanism under the application of a mathematical model or an algorithm. This results in the following control signal, which takes into account the deviation value of the working valve and can thereby be used for accurate control of the working valve.

[0013] According to a second inventive aspect, the object of the present invention is achieved by a method for operating a fluid system according to claim 2, wherein the method according to claim 2 differs from the method according to claim 1 only in that the method according to claim 2 is used for venting a fluid consumer and the working valve is therefore connected with its input connection to the fluid outlet or, if necessary, to a vacuum source.

[0014] The advantageous aspects of the method can be seen in that a continuous adaptation of the control signal for actuating the working valve is carried out during operation of the fluid system without requiring disruptive interventions such as test pulses or learning operations into the fluid system. If necessary, provision can be made to carry out a learning operation for the working valve when the fluid system is started up in order to ensure a particularly advantageous adaptation of the method to the actual conditions in the fluid system.

[0015] Advantageous developments of the invention are the subject matter of the dependent claims.

[0016] The control device expediently carries out a comparison between an actual pressure value determined from the sensor signal of the working pressure sensor and a model pressure value calculated on the basis of a mathematical model in order to determine the deviation value. In this case, the actual pressure value is advantageously available as the sensor signal of the working pressure sensor. The mathematical model describes the properties of the working valve and the fluid consumer connected to the working valve and calculates the model pressure value based on this, and is stored in an algorithm running in the control device.

[0017] It is therefore preferably provided that the control device determines the deviation value as a function of at least one characteristic value of a fluid consumer which is designed as a pneumatic cylinder and which is connected to the working valve via a hose, the at least one characteristic value originating from the following group: cylinder volume, dead volume, hose properties. In terms of the hose properties, in particular the diameter of the hose, the elasticity of the hose and the length of the hose are of interest (von Interesse, which can also be translated as interesting, important) in order to ensure that the conclusions of the mathematical model with respect to the model pressure values ​​are as close to the facts as possible.

[0018] In a further embodiment of the invention, it is provided that a control signal for actuating the working valve is used as an input variable for the mathematical model and that a valve characteristic curve of the working valve and characteristic values ​​of the fluid consumer are processed in the mathematical model.

[0019] Advantageously, according to the mathematical model, a linear displacement of the valve characteristic line of the working valve is performed with respect to the valve stroke, so as to determine the control signal depending on the actual pilot value, the linear displacement describing the relationship between the pilot value and the valve stroke. Due to aging phenomena in the working valve, a change in the relationship between the valve stroke and the pilot value (that is, the cross section available for the fluid flow through the valve) occurs, which aging phenomena can be attributed in particular to the plastic deformation of the rubber elastic sealing element. For example, the following situation can occur, that is, the sealing element arranged at the movable valve unit of the working valve undergoes a volume reduction due to long-term (langandauernde) loading. Exemplarily, it can be caused that the working valve is opened after a certain service duration under the condition of a smaller valve stroke than this is the case in the new state of the working valve. This change in the valve property can be described in a simple way by a linear displacement of the valve characteristic line along the following characteristic line axis, which represents the valve stroke. In the mathematical model, the control signal is adapted in this regard, so that the actual pilot value matches the theoretical pilot value with the smallest possible error.

[0020] In a further development of the method, it is provided that in the case of a transition between a ventilation process and an exhaust process or in the case of a transition between an exhaust process and a ventilation process, a reset of the mathematical model is correspondingly carried out and a restart of the mathematical model is carried out taking into account the actual pressure value of the working pressure sensor. This ensures that the mathematical model can always be compared with the current value of the sensor signal again in the case of such a transition and thus avoids error propagation.

[0021] Preferably, provision is made for the deviation value of the working valve to be determined cyclically and repeatedly during the actuation of the working valve. Preferably, the deviation value is determined in a digitally operating control at the same clock frequency as the actuation of the working valve, so that with each actuation process for the working valve, a correction of the control signal is also achieved and thus a valve actuation with as little error as possible is ensured at each time point of the actuation of the working valve.

[0022] Advantageously, a higher-level machine control connected to the control device provides a theoretical valve stroke for receipt by the control device or a higher-level machine control connected to the control device provides a theoretical guide value for receipt and processing by the control device into a theoretical valve stroke or performs determination of the theoretical valve stroke from a sensor signal of the sensor device in the control device.

[0023] According to a second aspect, the object of the invention is achieved by a fluid system for operating a fluid consumer. The fluid system comprises a control device and a working valve that can be controlled by the control device, the working valve comprising an input connection to which a fluid source and a supply pressure sensor are connected, and the working valve comprising an output connection to which a fluid consumer and a working pressure sensor are connected, and the output connection is assigned a position sensor for detecting a valve position, wherein a sensor device is assigned to the fluid consumer for detecting a movement state, and wherein the supply pressure sensor, the working pressure sensor and the sensor device are connected to the control device, wherein the control device is designed to provide a control signal for controlling the working valve as a function of a predeterminable setpoint value and an actual setpoint value that can be determined from a sensor signal of the position sensor, characterised in that the control device is designed to correct the control signal as a function of a deviation value of the working valve that can be determined from sensor signals of the supply pressure sensor, the working pressure sensor, the position sensor and the sensor device.

[0024] In an advantageous development of the fluid system, it is provided that the control device is designed to carry out the method according to any one of claims 1 to 6 .

[0025] According to a third inventive aspect, the object of the present invention is achieved by a computer program product for use in a computer system. Here, the computer program product includes instructions which, when executed in a control system of a fluid system, perform the method according to the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Advantageous embodiments of the present invention are shown in the accompanying drawings.

[0027] Figure 1 A strictly schematic illustration of a fluid system is shown,

[0028] Figure 2 A strictly schematic functional diagram is shown for the compensation of a valve characteristic which can be changed over time, and

[0029] Figure 3 A purely schematic representation of an initially determined valve characteristic line and a current valve characteristic line is shown. DETAILED DESCRIPTION

[0030] Purely for demonstration, Figure 1 The fluid system 1 shown in is designed to provide a linear adjusting movement and can be used for this purpose, by way of example, in a processing machine, not shown in greater detail, in order to temporarily fix and then release a workpiece, likewise not shown in greater detail.

[0031] The fluid system 1 comprises a control device 10 which is designed to actuate a working valve 11 , wherein the working valve 11 is provided to influence a fluid flow between a fluid source 15 , exemplarily embodied as a compressed air source, and a fluid consumer 16 , exemplarily embodied as a pneumatic cylinder.

[0032] For obvious reasons, Figure 1 In the illustration, only one ventilation branch 48 for the fluid consumer 16 is shown in detail, while an exhaust branch 49 is shown only schematically, which is constructed in principle identically and is only connected to a fluid outlet (not shown) and a sound buffer preferably arranged therein instead of being connected to the fluid source 15, and is connected to the control device 10 in the same way as the ventilation branch 48.

[0033] By way of example, it is provided that the control device 10 is not designed for indirectly controlling the working valve 11, as this can be the case, for example, in the embodiment of the working valve 11 as a solenoid valve. Rather, the control device 10 provides an electrical control signal to the pilot valves 19, 20 via the assigned control lines 17, 18. It is provided purely by way of example that the pilot valves 19, 20 are designed as 2 / 2 directional valves, in particular as piezo valves (Piezo-Ventile) and can be adjusted between a closed position and an open position depending on the control signal provided by the assigned control lines 17, 18. It is provided that the pilot valve 19 is connected to a compressed air source 26 on the input side and is connected to a control connection 22 of the working valve 11 via a fluid line 21 on the output side.

[0034] Furthermore, it is provided that the pilot control valve 20 is connected on the input side via a fluid line 23 to a control port 22 and on the output side to a sound damper 24 which forms a fluid outlet.

[0035] The working valve 11 is designed, for example, as a fluidically pilot-controlled 2 / 2-way valve, in which the valve unit 25 can close or release the fluid path between the inlet connection 27 and the outlet connection 28. In the closed position, as in Figure 1 As shown in FIG. 1 , the valve unit 25 rests in a sealing manner on a valve seat, which is formed, for example, by a surrounding sealing ring 29. Figure 1When the valve unit 25 moves in the opening direction, which is oriented downward in the figure, the sealing effect between the valve unit 25 and the sealing ring 29 is eliminated, so that a fluid flow can occur from the input connection 27 connected to the fluid source 15 to the output connection 28. In order to cause the opening movement for the valve unit 25, the valve unit 25 is connected to the working piston 31 via a coupling rod 30. The working piston 31, together with a section of the valve housing 32 of the working valve 11, delimits a variable-sized working space 33, which is connected to the control connection 22 in a communicating manner. A first end region of a return spring 34 is supported on the end side of the working piston 31 facing away from the working space 33, and a second end region of the return spring rests on an annular flange 35 of the valve housing 32. The return spring 34 is compressed when the working space 33 is subjected to pressure and the opening movement of the valve unit 25 caused by the pressure application and can, when the pressure in the working space 33 is subsequently reduced, cause a return movement for the working piston 31 and the valve unit 25 connected to the working piston, so as to establish the closed position for the working valve 11 again. By way of example, it is provided that the sealing ring 29 bears against the end face of the annular collar 35 which is opposite the restoring spring 34 .

[0036] The fluid consumer 16 is connected to the outlet port 28 of the working valve 11 via a supply line 36 and is designed to provide a linear working movement of a piston rod 38 movably accommodated in a cylinder housing 37 .

[0037] An exhaust branch 49 is also connected to the supply line 36, which has an internal structure equivalent to the ventilation branch 48 and is distinguished from the ventilation branch 48 only in that an unillustrated input connection of an unillustrated working valve is connected to the fluid outlet, so that the exhaust branch 49 can be used to exhaust the fluid consumer 16.

[0038] A pressure sensor 40, 41 is assigned to both the input connection 27 and the output connection 28, wherein the sensor signals of the pressure sensors 40, 41 are provided to the control device 10 via the assigned sensor lines 42, 43. In this case, the pressure sensor 40 is used as a supply pressure sensor, and the pressure sensor 41 is used as a working pressure sensor. In the case of the exhaust branch 49, the pressure sensor, which is arranged at the working valve, not shown, in the same way as the pressure sensor 40 and is also not shown, is referred to as an outlet pressure sensor.

[0039] Furthermore, it is provided that a displacement measuring system 44 is arranged on the fluid consumer 16 , which is designed to determine the position of the piston rod 38 and is connected to the control device 10 via a sensor line 45 .

[0040] Purely by way of example, it is provided that the control device 10 is connected via a bus communication line 3 to a machine control 2 which is designed to provide control commands to the control device 10 .

[0041] The functioning of the fluid system 1 with respect to providing a fluid flow to the fluid consumer 16 can be described as follows: When a control command is received from the machine control 2 to the control device 10, the control command is converted into a control signal for a respective one of the pilot valves 19, 20 in the control device 10. By actuating one of the pilot valves 19, 20, either a pressure increase or a pressure reduction in the working space 33 of the working valve 11 and a resulting change in the position of the working piston 31 and the valve unit 25 coupled thereto are effected.

[0042] This changes the cross section of the fluid path between the inlet connection 27 and the outlet connection 28 , thereby causing a change in the mass flow of the working fluid provided by the fluid source 15 , which is guided via the supply line 39 through the working valve 11 and the supply line 36 to the fluid consumer 16 .

[0043] In order to ensure the most precise possible actuation of the working valve 11, a schematic diagram of the control valve 11 is shown in the control device 10. Figure 2 , which includes a mathematical model that describes the properties of the working valve 11 and the fluid consumer 16 and can be supplied together with sensor signals of a supply pressure sensor 40, a working pressure sensor 41, a stroke measurement system 44 and a position sensor 46 assigned to the working valve 11 for determining the position of the valve unit 25 to a disturbance variable observer described in more detail below, which determines a deviation value for the working valve 11 and provides the deviation value for combination with a theoretical valve stroke and an actual valve stroke in order to thereby generate a new control signal for the working valve 11.

[0044] The new control signal can be characterized by a linear shift of the initial valve characteristic line 80 which is based on the working valve 11 and is determined in the new state of the working valve, as shown in FIG. Figure 3 The amount of the shift by which the initial valve characteristic line 80 must be shifted in order to reach the actual valve characteristic line 81 is determined according to the method presented below. The shift can be caused, for example, by aging phenomena at the rubber-elastic sealing element in the working valve 11 and, depending on the valve design, can result in a positive or negative characteristic line shift.

[0045] To carry out the method, it is assumed that Figure 1 The machine control unit 2 shown in FIG. Figure 2The theoretical guide value shown in 50 provides Figure 1 Alternatively, the theoretical pilot value 50 can also be calculated in the control device 10. The theoretical pilot value 50 corresponds to the opening cross section of the working valve 11 necessary for the fluid supply of the fluid consumer 16, which is also referred to as the orifice size of the working valve 11. The theoretical pilot value 50 is calculated in the control device 10 according to Figure 2 The representation of is linked to an inverted valve characteristic line 51 in order to obtain a set valve stroke 52 in this way.

[0046] The set valve stroke 52 is supplied to a stroke regulator 53 in the control device 10 , which is operated as part of an independent software application in particular. In the stroke regulator 53 , the set valve stroke 52 is processed with an actual valve stroke 54 determined from the sensor signal of the position sensor 46 and a deviation value 55 to form an actual stroke value 56 .

[0047] The actual stroke value 56 is used by the stroke regulator 53 as a control signal for the working valve 11, in particular as a control signal for one of the pilot control valves 19. Figure 2 In the illustration of FIG. 1 , a hub offset 58 which occurs in practice due to the sealing properties of the sealing ring 29 which are dependent on time and / or on changes in the operating conditions of the working valve 11 is indicated by a dashed arrow as an influencing variable to be taken into account for the conversion of the actual stroke value 56 into the actual valve opening of the working valve 11, without this being an input variable which is explicitly supplied to the actual stroke value 56. Rather, the hub offset 58 occurs in practice inherently as a disturbance variable and leads to an undesirable deviation between the actual stroke value 56 predefined by the stroke regulator 53 and the resulting actual pilot value 60 which results in the working valve 11 based on the provision of the actual stroke value 56 (in combination with the hub offset 58).

[0048] The actual stroke value 56 provided by the stroke regulator 53 to the working valve 11 is converted here into an actual pilot value 60 and thus into the opening cross section (hole size) of the working valve 11 by the properties of the working valve 11, which are represented as a valve characteristic line 59, that is, as a relationship between the actual stroke value 56 and the pilot value resulting therefrom. The actual pilot value 60 is converted by the working valve 11 into an actual mass flow 68, which leads to pressure dynamics 67 at the fluid consumer 16. The pressure dynamics 67 depend on the input variables which are respectively represented by arrows and which are respectively provided with only reference numerals for reasons of clarity:

[0049] • Input pressure 61 (sensor signal from pressure sensor 40)

[0050] • Output pressure 62 (sensor signal from pressure sensor 41)

[0051] • The predeterminable cylinder volume 63 of the fluid consumer 16

[0052] • Predeterminable dead volume 64 of the fluid consumer 16

[0053] • Predeterminable hose properties 65 of the fluid line 21 between the operating valve 11 and the fluid consumer 16

[0054] • Movement signal 66 (sensor signal of the travel measuring system 44)

[0055] The pressure dynamics 67 of the fluid consumer 16 lead, on the one hand, to the control movement of the fluid consumer 16 (not shown) and, on the other hand, to the output pressure 62 which can be measured at the output connection 28 of the working valve 11.

[0056] Furthermore, the actual travel value 56 is used as an input signal for a mathematical model 57, in which a pressure 74 is determined by an algorithm which is used in the control device 10 and is in particular executed as part of an independent software application. For this purpose, the actual travel value 56 is firstly linked to the valve characteristic line 59 in order to calculate a pilot value 70. The calculated pilot value 70 is then provided to a valve model 71, where it is converted into a model mass flow 72. The model mass flow 72 is provided to a pressure dynamics model 73, which is designed to calculate a pressure 74 from the model mass flow 72.

[0057] The calculated pressure 74 is then linked to the measured pressure 62 (in particular by means of a difference), and the result of this calculation is supplied to an algorithm for an observer stabilization 75 , which is coupled back to the pressure dynamics model 73 .

[0058] Furthermore, the result of the mathematical operation between the calculated pressure 74 and the measured pressure 62 is supplied to a disturbance observer 76, which, for example, as an integrator integrates the result of the current mathematical operation with the result of the previous operation between the calculated pressure 74 and the measured pressure 62 and is designed, for example, such that a target value close to zero is reached for the integration. In order to reach the target value, the disturbance observer 76 can determine, based on the respectively current result of the integration, a deviation value 55 which serves as an input variable for the stroke regulator 53 and whose magnitude at least substantially corresponds to the magnitude of the stroke offset 58 and whose sign is respectively opposite to the sign of the stroke offset 58, in order to thereby achieve the most complete possible compensation of the stroke offset 58. Since the disturbance observer 76 also includes the input value for the pressure dynamics 67 when determining the deviation value 55, the sensor signals of the supply pressure sensor 40, the working pressure sensor 41, the position sensor 46 and the stroke measuring system 44 are taken into account in this process.

Claims

1. A method for operating a fluid system, the fluid system comprising a control device (10), a working valve (11) which can be controlled by the control device (10), the working valve comprising an input connection (27), to which a fluid source (15) and a supply pressure sensor (40) are connected, and the working valve comprising an output connection (28), to which a fluid consumer (16) and a working pressure sensor (41) are connected, and the output connection is assigned a position sensor (46) for detecting a valve position, in, The fluid consumer (16) is equipped with a sensor device (44) for detecting a movement state, wherein the supply pressure sensor (40), the working pressure sensor (41) and the sensor device (44) are connected to the control device (10), characterized in that the control device (10) performs the following steps: receiving or determining a theoretical valve stroke, determining an actual valve stroke based on a sensor signal of the position sensor (46), determining a deviation value of the working valve (11) based on the sensor signals of the supply pressure sensor (40), the working pressure sensor (41), the position sensor (46) and the sensor device (44), and processing the theoretical valve stroke, the actual valve stroke and the deviation value into a control signal for actuating the working valve (11), and providing the control signal to the working valve (11).

2. A method for operating a fluid system, the fluid system comprising a control device (10), a working valve that can be controlled by the control device (10), the working valve comprising an input connection, to which a fluid outlet and an outlet pressure sensor are connected, and the working valve comprising an output connection, to which a fluid consumer (16) and a working pressure sensor (41) are connected, and the output connection is assigned a position sensor for detecting a valve position, in, The fluid consumer (16) is equipped with a sensor device (44) for detecting the movement state, wherein the outlet pressure sensor, the working pressure sensor (41) and the sensor device (44) are connected to the control device (10), characterized in that the control device (10) performs the following steps: receiving or determining a theoretical valve stroke, determining an actual valve stroke based on a sensor signal of the position sensor, determining a deviation value of the working valve based on the sensor signals of the outlet pressure sensor, the working pressure sensor (41), the position sensor (46) and the sensor device (44), and processing the theoretical valve stroke, the actual valve stroke and the deviation value into a control signal for actuating the working valve and providing the control signal to the working valve.

3. The method according to claim 1 or 2, It is characterized in that To determine the deviation value, the control device carries out a comparison between an actual pressure value determined from a sensor signal of the working pressure sensor (41) and a model pressure value calculated on the basis of a mathematical model.

4. The method according to claim 3, It is characterized in that The control device determines the deviation value as a function of at least one characteristic value of a fluid consumer (16) which is designed as a pneumatic cylinder and is connected to the working valve (11) via a hose, the at least one characteristic value originating from the following group: cylinder volume, dead volume, hose properties.

5. The method according to claim 4, It is characterized in that A control signal for actuating the working valve (11) is used as an input variable for the mathematical model, and in the mathematical model a valve characteristic line (80, 81) of the working valve (11) and characteristic values ​​of the fluid consumer (16) are processed.

6. The method according to claim 5, It is characterized in that According to the mathematical model, a linear shift of a valve characteristic line (80, 81) of the working valve (11) is performed with respect to the valve stroke in order to determine the control signal as a function of an actual pilot value, the linear shift describing the relationship between pilot value and valve stroke.

7. The method according to claim 3, It is characterized in that At the transition between a ventilation process and an exhaust process or between an exhaust process and a ventilation process, the mathematical model is reset and restarted taking into account the actual pressure value of the working pressure sensor (41).

8. The method according to claim 1 or 2, It is characterized in that The determination of the deviation value of the working valve (11) is carried out cyclically and repeatedly during the actuation of the working valve (11).

9. The method according to claim 1 or 2, It is characterized in that A higher-level machine control unit connected to the control mechanism (10) provides the theoretical valve stroke for receipt by the control mechanism (10), or a higher-level machine control unit (2) connected to the control mechanism (10) provides a theoretical guide value for receipt and processing into the theoretical valve stroke by the control mechanism (10), or the theoretical valve stroke is obtained in the control mechanism (10) from a sensor signal (66) of the sensor mechanism (44).

10. A fluid system (1) for operating a fluid consumer (16), comprising a control device (10), a working valve (11) which can be controlled by the control device (10), the working valve comprising an input connection (27), to which a fluid source (15) and a supply pressure sensor (40) or a fluid outlet and an outlet pressure sensor are connected, and the working valve comprising an output connection (28), to which a fluid consumer (16) and a working pressure sensor (41) are connected, and the output connection is assigned a position sensor (46) for detecting a valve position, in, The fluid consumer (16) is assigned a sensor device (44) for detecting a movement state, wherein the supply pressure sensor (40) and the working pressure sensor (41) are connected to the control device (10), and the sensor device (44) is connected to the control device (10), wherein the control device (10) is designed to provide a control signal for actuating the working valve (11) as a function of a predeterminable setpoint guide value and an actual guide value ascertainable from a sensor signal of the position sensor (46), and characterized in that the control device (10) is designed to correct the control signal as a function of a deviation value of the working valve (11) ascertainable from sensor signals of the supply pressure sensor (40) or the outlet pressure sensor, the working pressure sensor (41), the position sensor (46) and the sensor device (44).

11. The fluid system according to claim 10, It is characterized in that The control device (10) is designed to carry out the method according to any one of claims 1 to 9.

12. A computer program product for use in a computer system, comprising instructions which, when executed in a control system (10) of a fluid system (1), carry out the method according to any one of claims 1 to 9.

Images