Method for detecting a blockage state, and pneumatic system

Abstract

The invention relates to a method for detecting a blockage state of at least one actuating portion of a pneumatic system for industrial automation, said system comprising at least one pneumatic actuator and a valve device which has a pressure control unit and is used to pneumatically actuate the pneumatic actuator using an output pressure of the pressure control unit in order to thereby set the actuating portion into motion. The method has the following steps: providing a target pressure curve s, - carrying out a closed-loop pressure control of the output pressure according to the target pressure curve in order to pneumatically actuate the pneumatic actuator, - detecting an actuation signal, by means of which a valve unit of the pressure control unit is actuated as part of the closed-loop pressure control, and - detecting the blockage state on the basis of the detected actuation signal.

Description

[0001] Festo SE & Co. KG, Ruiter Straße 82, 73734 Esslingen

[0002] Method for detecting a blockage condition and pneumatic system

[0003] The invention relates to a method for detecting a blockage state of at least one actuating section of a pneumatic system for industrial automation, comprising at least one pneumatic actuator and a valve device which has a pressure regulator unit and serves to pneumatically actuate the pneumatic actuator with an output pressure of the pressure regulator unit in order to thereby set the actuating section in motion.

[0004] One task of the invention is to efficiently detect the blockage state of the actuator section.

[0005] The task is solved by a procedure with the following steps: performing pressure control of the output pressure according to the target pressure curve in order to pneumatically actuate the pneumatic actuator, detecting a control signal with which a valve unit of the pressure regulator unit is controlled as part of the pressure control, and detecting the blockage state based on the detected control signal.

[0006] A blockage state is defined in particular as a state in which the actuating section does not move despite pneumatic actuation of the pneumatic actuator (and a driving force, in particular pneumatic, applied to the actuating section as a result).

[0007] The blockage state can occur, for example, when an object, such as a wafer, which is to be set in motion by means of the actuating section, cannot be set in motion despite pneumatic actuation of the pneumatic actuator and a resulting driving force applied to the object by the actuating section.

[0008] The actuating section can include an actuator element (of the pneumatic actuator). The blockage state can also occur, in particular, when the actuator element is in an end position where it rests against an end stop.

[0009] The control signal is, for example, an electrical and / or digital signal. The control signal is specifically not a pneumatic signal. The control signal serves, in particular, to adjust the size of a valve opening through which compressed air flows to or from a pressure chamber of the pneumatic actuator. Advantageously, the volume of the pressure chamber changes when the actuating section moves.

[0010] For example, if the pneumatic actuation of the pneumatic actuator is directed towards a movement of the actuating section in which the volume of the pressure chamber would increase in a non-blockage state (i.e., where no blockage is present), the blockage state can be recognized by the fact that, within the framework of the pressure control implemented for the pneumatic actuation, the control signal (especially for the same target pressure profile and / or for the same target pressure value of the target pressure profile) is smaller or requests a smaller valve opening than in the non-blockage state. This is because, when the blockage state is present—i.e.,If the actuator section does not move – and therefore there is no increase in the volume of the pressure chamber – then the pressure regulator unit must admit less compressed air into the pressure chamber compared to the non-blocked state (since the volume of the pressure chamber does not increase due to the blockage) in order to achieve the target pressure profile. Consequently, in the blocked state, the pressure regulator unit will provide a control signal with a smaller signal value (or a control signal that causes a smaller valve opening) than in the non-blocked state. The blocked state can therefore be detected based on the control signal.

[0011] Advantageous further training is the subject of the subclaims.

[0012] The invention further relates to a pneumatic system for industrial automation, comprising at least one pneumatic actuator and a valve assembly. The valve assembly includes a pressure regulator unit with a valve unit and is configured to perform pressure regulation with the pressure regulator unit according to a setpoint pressure profile in order to pneumatically actuate the pneumatic actuator, thereby setting a control section of the pneumatic system in motion. The valve assembly is further configured to detect a control signal with which the valve unit is actuated within the framework of pressure regulation and to detect a blockage state of the control section based on the detected control signal. Further exemplary details and exemplary embodiments are explained below with reference to the figures.

[0013] Figure 1 is a schematic representation of a pneumatic system.

[0014] Figure 2 shows a block diagram of a signal flow in a pneumatic system.

[0015] Figure 3 shows a diagram with a position curve, pressure curve and a control signal curve, and

[0016] Figure 4 is a diagram of a position-pressure mapping.

[0017] Figure 1 shows an exemplary embodiment of a pneumatic system 1 for industrial automation. The pneumatic system 1 is used, for example, for handling a wafer 2. The pneumatic system 1 is implemented, for instance, as a so-called pinlifting system. The pneumatic system 1 is used, for example, in a semiconductor plant.

[0018] The pneumatic system 1 comprises a valve device 3 and at least one pneumatic actuator 4. The valve device 3 serves to pneumatically actuate the at least one pneumatic actuator 4. By way of example, the pneumatic system 1 comprises several, in particular exactly three, pneumatic actuators 4: a first pneumatic actuator 4a, a second pneumatic actuator 4b, and a third pneumatic actuator 4c. Each pneumatic actuator 4 is exemplified as a pneumatic drive cylinder. Preferably, each pneumatic actuator 4 is not designed as a valve. The valve device 3 serves to pneumatically actuate several, in particular all, of the pneumatic actuators 4.

[0019] Each pneumatic actuator 4 has a respective actuator element 5, which is exemplified as a piston assembly. Each piston assembly has a respective piston and, exemplified, a respective piston rod. Each pneumatic actuator 4 has a respective pressure chamber 6, which can be selectively pressurized or vented via the valve device 3 to set the respective actuator element 5 in motion. For example, each pneumatic actuator 4 is designed as a single-acting actuator. In particular, each pneumatic actuator 4 has only one pressure chamber 6 and / or one spring 7 acting on the respective actuator element 5.

[0020] Alternatively, one, several or all pneumatic actuators can be designed to be double-acting and in this case each include a second pressure chamber and / or each no spring 7 .

[0021] For example, each pneumatic actuator 4 has a respective actuator housing 38 in which the respective actuator element 5 and / or the respective pressure chamber 6 is expediently arranged.

[0022] The pneumatic actuators 4 are preferably of identical construction to each other.

[0023] Advantageously, the pneumatic system 1 does not have position sensors to detect the position of an actuator 5. In particular, the pneumatic system 1 does not have a displacement measuring system to detect the position of the actuator 5 along its (entire possible) path of movement.

[0024] The respective actuator 5 can be moved into a first end position, in which the actuator 5 is, for example, in a fully retracted position, and / or into a second end position, in which the actuator 5 is in a fully extended position. The term "end position" refers in particular to a position in which the actuator 5 can no longer be moved, especially in the direction in which it was moved to reach the end position. For example, the actuator 5 rests against a respective end stop in each end position.

[0025] The valve device 3 comprises, by way of example, at least one pressure regulator unit 9. Optionally, the valve device 3 comprises several, in particular exactly three, pressure regulator units 9. Each pressure regulator unit 9 is expediently assigned to a respective pneumatic actuator 4 and serves to selectively pressurize or vent the pressure chamber 6 of the respective assigned pneumatic actuator 4. By way of example, each pressure regulator unit 9 is designed as a separate module, in particular as a plate-shaped module. By way of example, the pressure regulator units 9 are arranged in a series. For example, the pressure regulator units 9 form a valve manifold or are part of a valve manifold. Expediently, each pressure regulator unit 9 is connected to a compressed air source (not shown).

[0026] Each pressure regulator unit 9 is configured to provide a respective output pressure with which the pressure chamber 6 of the respective associated pneumatic actuator 4 is actuated. For example, each pressure regulator unit 9 has a respective valve unit 12 through which the pneumatic actuation of the respective associated pneumatic actuator 4 takes place. For example, each valve unit 12 is designed as a piezoelectric valve unit. Preferably, each valve unit 12 is designed as a proportional valve unit.

[0027] For example, each pressure regulator unit 9 has a respective control unit 13 for controlling the respective valve unit 12, in particular with a control signal 34. Each control unit 13 is, for example, implemented as a microcontroller.

[0028] According to an alternative embodiment, the valve device 3 comprises a control unit, in particular a microcontroller, which provides a respective control signal for each valve unit. Advantageously, in this case, each pressure regulator unit is formed from a combination of this single control unit and a respective valve unit. In particular, in this case, several pressure regulator units share one control unit. The pressure regulator units are, in this case, in particular functional units.

[0029] Each pressure regulator unit 9 is pneumatically connected to a respective pneumatic actuator 4 via a respective pneumatic line 10 of the pneumatic system 1. The pneumatic lines 10 are, for example, hoses.

[0030] For example, pneumatic system 1 has several pressure sensors 14. For example, each pressure regulator unit 9 has a respective pressure sensor 14. The pressure sensors 14 serve in particular to detect the respective output pressure - i.e., in particular the pressure of the compressed air in the respective associated pneumatic line 10 and / or the respective associated pressure chamber 6 - and in particular to provide it as an actual pressure value 29.

[0031] Advantageously, each control unit 13 performs a comparison of a current setpoint pressure value of one of the setpoint pressure curves 25 supplied to the respective pressure regulator unit 9 with the respective actual pressure value 29 and, based on the comparison, controls the respective valve unit 12 with the respective control signal 34 in order to cause the output pressure to change towards the setpoint pressure value.

[0032] Each pressure regulator unit 9 has, by way of example, a respective (in particular plate-shaped) pressure regulator unit housing 15 in which the respective valve unit 12, the respective control unit 13 and / or the respective pressure sensor 14 is preferably arranged. The pressure regulator units 9 are preferably identical in construction to one another.

[0033] By way of example, the valve device 3 further comprises a control unit 11, which is designed in particular as a higher-level control unit, for example as a PLC (programmable logic controller). The control unit 11 is expediently connected to the pressure regulator units 9 via one or more communication lines 16 and expediently transmits setpoint pressure profiles 25 to the pressure regulator units 9 via these communication lines 16. The setpoint pressure profiles 25 can also be provided externally, for example by an external control unit.

[0034] According to an optional embodiment, the control unit 11 and the pressure regulator units 9 are integrated into a single device. For example, the valve device 3 comprises a valve device housing, which in particular represents the outer housing of the valve device 3. The control unit 11 and the pressure regulator units 9 are expediently arranged in the valve device housing. Optionally, the function of the control units 13 can be implemented on the control unit 11 in this case.

[0035] For example, pneumatic system 1 has a wafer support 17 for placing the wafer 2. The wafer support 17 has, for example, a wafer support surface 18, which is expediently oriented vertically upwards with its normal vector. Preferably, pneumatic system 1 has a holder for the wafer 2, and the wafer support 17 is part of the holder. The holder can also be called a chuck. The wafer support 17 is, for example, designed as a round plate.

[0036] The holding device is specifically designed to hold the wafer 2 on the wafer support 17 by means of an electrical force, in particular an electrostatic force. Advantageously, the electrical force counteracts the lifting of the wafer 2 from the wafer support 17. The holding device can be selectively moved into a holding state, in which the holding device holds the wafer 2 on the wafer support 17, or into a release state, in which the holding device releases the wafer 2.

[0037] The pneumatic system 1 includes, by way of example, a positioning arrangement 19, movable relative to the wafer support 17 by means of pneumatic actuators 4, which serves to position the wafer 2 relative to the wafer support 17. In particular, the positioning arrangement 19 serves to lift the wafer 2 from the wafer support 17 and / or to lower it onto the wafer support 17. Specifically, the wafer 2 is lifted vertically upwards from the wafer support 17 by means of the positioning arrangement 19, as indicated by the arrow 22. The positioning arrangement 19 includes several contact points 21 for supporting the wafer 2. By way of example, the positioning arrangement 19 includes exactly three contact points 21 for supporting the wafer 2. Advantageously, the three contact points 21 are located at the same height and / or are distributed relative to each other within a horizontal plane.Preferably, when lifting or lowering the wafer 2 by means of the positioning arrangement 19, it rests exclusively on the contact points 21.

[0038] For example, each contact point 21 is assigned to a respective pneumatic actuator 4. In particular, each contact point 21 is set in motion by a respective pneumatic actuator 4. For example, each contact point 21 is part of a respective actuator element 5, in particular a respective piston rod. For example, each contact point 21 is formed by one end of a respective piston rod. Furthermore, each contact point 21 can be part of a respective contact section 20, wherein each contact section 20 is coupled to a respective actuator element 5, in particular attached to it. For example, each contact section 20 is attached to a respective piston rod. The contact sections 20 are in particular part of the positioning arrangement.

[0039] The pneumatic system 1 is expediently designed, starting from a state in which the wafer 2 rests on the wafer support 17 and the holding device is in the holding state, first to move the holding device into the release state and then to lift the wafer 2 from the wafer support 17 by means of the positioning arrangement 19.

[0040] It can happen – for example, due to a defect in the holding device – that the pneumatic system 1 attempts to lift the wafer 2 from the wafer support 17 using the positioning arrangement 19, while the holding device is still in the holding state (and continues to hold the wafer 2 on the wafer support 17). In this situation, the force applied to the wafer 2 by the positioning arrangement 19 can damage the wafer 2. This situation is an example of a blockage state of an actuating section. The actuating section is formed, for example, by the actuator element 5 and / or the contact section 20.

[0041] The following section will explain in more detail how a blockage state of an actuating section of the pneumatic system can be detected. For example, each actuating section comprises a respective actuator 5 and / or a respective contact section 20. For example, the pneumatic system 1 comprises three actuating sections, each of which has a respective actuator 5 and a respective contact section 20 that is motion-coupled with, and in particular attached to, the respective actuator 5. The following explanations relating to the detection of a blockage state of an actuating section expediently apply to each of the actuating sections. In particular, the valve device 3 is designed to detect a respective blockage state for each actuating section.The explanations relating to a pressure regulator unit 9 and / or a pneumatic actuator 4 shall apply accordingly to each pressure regulator unit 9 and each pneumatic actuator 4, respectively. The valve device 3 serves to pneumatically actuate the pneumatic actuator 4 with the output pressure of the pressure regulator unit 9 in order to set the actuating section in motion.

[0042] The pneumatic system 1, in particular the valve device 3, provides a target pressure profile 25. The target pressure profile 25 is generated, for example, by the controller 11 and transmitted to the pressure regulator unit 9. Furthermore, the target pressure profile 25 can be provided externally, for example, by an external control unit. The target pressure profile 25 comprises a plurality of successive target pressure values, each expediently defining a target pressure for the output pressure.

[0043] The valve device 3, together with the pressure regulator unit 9, performs pressure regulation to pneumatically actuate the pneumatic actuator 4. The pressure regulator unit 9 regulates its output pressure to the current value of the setpoint pressure curve. This, for example, vents the pressure chamber 6, thereby exerting a pneumatic driving force on the actuator element 5.

[0044] The valve device detects a control signal with which the valve unit of the pressure regulator unit 9 is controlled as part of the pressure regulation. As already mentioned, the control signal is in particular an electrical and / or digital signal and serves in particular to set a size of a valve opening through which compressed air flows for the pneumatic actuation of the pneumatic actuator 4f.

[0045] The valve device 3 detects the blockage state based on the detected control signal. For example, the valve device 3, in particular the controller 11 and / or the control unit 13, analyzes the temporal profile of the detected control signal and determines, based on this analysis, that a blockage state exists. Preferably, based on this determination, the valve device 3 generates blockage information indicating that a blockage state exists.

[0046] The following section will discuss blockage detection in the exemplary case where the pneumatic system 1 comprises several actuating sections, several pneumatic actuators 4 and several pressure regulator units 9.

[0047] Each pressure regulator unit 9 serves to pneumatically actuate a respective pneumatic actuator 4 with its respective output pressure, thereby setting a respective actuating section in motion. Each pressure regulator unit 9 performs a pressure regulation of its respective output pressure according to the setpoint pressure profile or a specific setpoint pressure profile in order to pneumatically actuate the respective pneumatic actuator 4. For example, the same setpoint pressure profile is used for each pressure regulator unit 9, or an individual setpoint pressure profile is used for each pressure regulator unit 9. The valve device 3 (for example, the controller 11) detects a respective control signal 34 for each pressure regulator unit 9, which is used to actuate a respective valve unit of the respective pressure regulator unit 9 within the framework of the respective pressure regulation.The valve device 3 (for example, the controller 11) detects a respective blockage state for each actuating section based on the respective detected control signal. Optionally, the valve device 3 (in particular the controller 11) generates a respective blockage information for each actuating section in which the blockage state exists, indicating the blockage.

[0048] Optionally, the control signals 34 for the valve units 12 can be provided by the controller 11. In this case, the controller 11 specifically controls the valve units 12 with the control signals 34. The controller 11 is, in particular, a real-time capable controller, for example, a PLC.

[0049] The following section will discuss the blockage state in more detail.

[0050] The actuating section serves, for example, to set an object in motion. The object in this example is wafer 2. A blockage state exists, in particular, when the object cannot be set in motion despite pneumatic actuation of the pneumatic actuator 4 and the resulting driving force applied to the object by the actuating section.

[0051] Preferably, the actuating section serves to lift the wafer 2 from the wafer support 17. The blockage state occurs particularly when the wafer cannot be lifted from the wafer support 17 despite pneumatic actuation of the pneumatic actuator 4 and the resulting drive force applied to the wafer 2 by the actuating section. For example, the wafer support 17 is part of a wafer holding device that, in particular, faultily holds the wafer 2 in the blockage state, thus preventing it from being lifted. The wafer holding device is part of the pneumatic system 1. The blockage state can occur particularly when the wafer holding device faultily fails to switch from the holding state to the release state.

[0052] Preferably, the pneumatic system is switched to a safety state upon detection of a blockage. For example, the controller 11 requests the safety state upon receiving blockage information. In the safety state, each pneumatic actuator 4 is switched to a predefined state. For example, in the safety state, each pneumatic actuator 4 is de-energized, in particular by the valve device 3 venting each pneumatic actuator 4. Furthermore, in the safety state, each actuating section, in particular each actuator element 5, can be moved to a predetermined position, for example, an end position, in particular a fully retracted position, and / or a zero position.

[0053] With reference to the block diagram shown in Figure 2, an exemplary signal flow in the pneumatic system 1 will be discussed below. In the example shown, the controller 11 and the pressure regulator unit 9 are shown as separate blocks. Preferably, the controller 11 and one, several, or all of the pressure regulator units 9 can be implemented in a single device.

[0054] The control unit 11 comprises a trajectory planner 26, which receives a target position signal 27 that defines a target position. Based on the target position signal 27, the trajectory planner 26 calculates a target position profile 24 and provides this to a position controller 28, which (for example, using a position-pressure curve 23) converts the target position profile 24 into a target pressure profile 25 and transmits this to the respective pressure regulator unit 9, in particular as an electrical signal.

[0055] The pressure regulator unit 9 compares a current setpoint value of the setpoint curve s 25 with an actual pressure value 29 determined by means of the pressure sensor 14 and performs a venting or aeration of the pressure chamber 6 by means of the valve unit 12 in order to change the actual pressure value 29 towards the setpoint value .

[0056] The control unit 11 also includes, by way of example, a blockage detection unit 33, which is configured to detect the blockage state based on the control signal 34. Optionally, the blockage detection unit 33 provides blockage information 42 based on the detected blockage state, in particular to the position control unit 28.

[0057] As an example, each pressure regulator unit 9 provides its control signal 34 to the respective blockage detection unit 33. The control signal 34 is, in particular, an electrical or digital signal. The control signal 34 is advantageously used to control the valve unit 12 in the pressure regulator unit 9 in order to adjust the size of a valve opening through which compressed air flows into (or out of) the pressure chamber 6.

[0058] The trajectory planner 26, the position control 28, and / or the blockage detection unit 33 are preferably implemented as software components, which are expediently executed on a processor of the controller 11.

[0059] Figure 2 shows only one pneumatic actuator 4; as explained above, preferably several, in particular three, pneumatic actuators 4 are present. Preferably, each pneumatic actuator 4 has a respective position control 28 and / or a respective blockage detection unit 33, which is / are designed in particular as explained above.

[0060] The following section will explain in more detail how the blockage state can be detected based on the control signal 34.

[0061] Preferably, the valve device 3 is configured to recognize a signal characteristic in the detected control signal, in particular in the temporal progression of the control signal. The valve device 3 is preferably configured to recognize the blocked state based on the detected signal characteristic.

[0062] The control signal is used in particular to adjust the size of a valve opening through which compressed air flows to or from a pressure chamber of the pneumatic actuator. For example, the volume of the pressure chamber changes when the actuating section moves.

[0063] Figure 3 shows the time profiles of a control signal 34, a pressure profile s 35, and a position z of a control section, in particular an actuator 5, for example, during a vertical upward movement of the actuator 5. The pressure profile 35 is, for example, a setpoint pressure profile with which the pressure regulator 9 is controlled, in particular by the controller 11. Alternatively, the pressure profile 35 can also be the profile of the output pressure—in particular, the actual pressure value 29—of the pressure regulator 9. By way of example, the pressure profile 35 has the form of an ascending straight line. The pressure regulator 9 sets its output pressure according to the setpoint pressure profile and generates the control signal 34 for this purpose. At a first time tl, the actuator 5 begins to move. At this first point in time tl, a signal characteristic 36, in particular a signal step, occurs in the control signal 34 as an example.At a second time t2, when the actuator element 5 is blocked and does not move further, a signal characteristic 37, e.g. a signal jump, occurs in the control signal 34, which is expediently detected by the blockage detection unit 33 in order to recognize the blockage state.

[0064] The signal characteristics 36, 37 occur as an example because the movement of the actuator 5 changes the volume of the pressure chamber 6, in particular increasing it, so that the pressure regulator unit 9 has to provide more compressed air t during the movement (and accordingly has to provide a larger valve opening for the supplied compressed air t via the control signal 34) in order to achieve the pressure profile 35, compared to the state in which the actuator 5 is not moving.

[0065] At the second time point t2, the actuator 5 is in the blocked state and does not move further. At the second time point t2, the time course of the control signal 34 exhibits the second signal characteristic 37 – for example, a downward jump.

[0066] It is also possible that the actuator is in a blocked state from the outset, so that it is not moved at all during pressure control. In this case, the signal characteristic used to detect the blocked state can, for example, include the absence of a signal step, such as the absence of an upward signal step, and / or a straight, particularly constant, signal segment of a predetermined minimum length and / or within a predetermined time window and / or within a predetermined pressure range.

[0067] Preferably, the valve device 3, in particular the control unit 11, detects the blockage state by comparing a signal waveform of the detected control signal with a reference signal waveform. The reference signal waveform is expediently stored in the valve device 3, in particular the control unit 11. The reference signal waveform preferably corresponds to a signal waveform of the control signal 34 in a state in which the blockage state does not exist. The reference signal waveform is determined, for example, in advance, in particular during commissioning of the pneumatic system 1. To detect the blockage state, the valve device 3 can determine a deviation between the reference signal waveform and the detected time course of the control signal 34 and assess whether the deviation is within or outside a tolerance range.If the deviation is outside the tolerance range, the valve device can detect the presence of a blockage condition.

[0068] Preferably, the valve device 3, in particular the control unit 11, detects the blockage state by considering a pressure signal profile, in particular the target pressure profile and / or a detected actual pressure profile. For example, the valve device 3 can check whether a relationship exists between the pressure signal profile and the control signal 34, in particular the temporal profile of the control signal 34, or whether an expected relationship exists between the pressure signal profile and the control signal 34, in particular the temporal profile of the control signal. The expected relationship can, for example, be stored in the valve device 3, in particular the control unit 11. The expected relationship defines, for example, an expected value or range of values ​​for the control signal 34 for one, several, or all pressure values ​​of the pressure signal profile.

[0069] The target pressure curve 25 is, for example, a predetermined reference trajectory of the pressure and the valve device 3 can detect a change in the control signal required for this reference trajectory and, based on this detection, recognize the blockage state.

[0070] Preferably, the blockage state is detected without using a position sensor for the actuating section. As explained above, the blockage state can be detected based on the control signal 34, so that a position sensor is not required for this purpose.

[0071] Advantageously, the actuating section (by pneumatic actuation of the pneumatic actuator 4) is movable in two opposite directions. Preferably, the valve device 3 is designed to detect the blockage state for both directions of movement based on the control signal 34.

[0072] The following section will explain in more detail how the detection of the blockage state can be used to determine that the actuator 5 is in an end position. Preferably, the actuating section includes an actuator 5, and the blockage state is present when the actuator 5 is in an end position where it rests against an end stop. The end stop is, for example, part of the actuator housing 38. As explained above, the blockage state can be detected based on the control signal 34. By detecting the blockage state, it becomes possible to determine the end position of the actuator 5 without a corresponding position sensor, such as a limit switch. Consequently, it is preferably possible to dispense with a limit switch to detect that the actuator 5 is in the end position.

[0073] Advantageously, when detecting that the actuator 5 is in an end position, the valve device 3 takes into account a pressure signal profile, in particular the target pressure profile and / or the actual pressure profile. For example, the valve device 3 checks whether the control signal 34 behaves in a predetermined way at a predetermined pressure value or pressure range of the pressure signal profile, for example, whether it lies within a predetermined value range.

[0074] Furthermore, a predetermined pressure range (for the set pressure and / or the actual pressure) can be defined in the valve device 3, within which the actuator 5 can reach the end position, and the valve device 3 can, for example, be configured to selectively check a section of the time course of the control signal 34 associated with this pressure range for the presence of the signal characteristic (indicating the blockage state). The section of the time course of the control signal 34 associated with the pressure range contains, in particular, those values ​​of the control signal 34 with which the pressure values ​​of the pressure range were achieved and / or which were provided to achieve the pressure values ​​of the pressure range.

[0075] The following section will explain in more detail how a position-pressure curve 23 can be generated based on a final pressure value (and preferably a start pressure value). The position-pressure curve 23 can be used by the valve device 3 to convert the target position profile 24 into a target pressure profile 25.

[0076] The detection of the initial pressure value and / or final pressure value preferably takes place during a learning run, in which the actuator element 5 is moved, for example, from the first end position to the second end position (by means of pneumatic actuation of the pneumatic actuator 4).

[0077] Preferably, the valve device 3 is configured to detect a final pressure value with which the pneumatic actuator 4 is actuated when the actuator element 5 reaches the end position. The valve device 3 is preferably configured to generate a position-pressure mapping 23 based on the final pressure value, which describes a relationship between the output pressure and a position of the actuator element.

[0078] Preferably, the valve device 3 is configured to use the position-pressure mapping 23 to convert a target position for the actuator element 5 into an output pressure for actuating the pneumatic actuator in order to move the actuator element into the target position. The initial pressure value describes the pressure (in particular, output pressure) with which the respective pneumatic actuator 4 is actuated by the valve device 3 when the respective actuator element 5 begins to move. The initial pressure value can also be referred to as the breakaway pressure. The initial pressure value is, in particular, the pressure required to cause the actuator element 5 to begin moving, especially from an end position.

[0079] With reference to Figure 3, the following will discuss an exemplary recording of the initial pressure value ps and the final pressure value pe.

[0080] At the first time point tl, the actuator 5 begins to move, and the time course of the control signal 34 exhibits the first signal characteristic 36 – for example, a jump upwards. In response to this first signal characteristic 36, the blockage detection unit 33 detects the pressure value of the pressure curve s 35 present at the first time point tl as the initial pressure value ps.

[0081] In response to the (previously discussed) second signal characteristic 37, the blockage detection unit 33 detects the current pressure value 29 present at the second time t2 (or the pressure value of the pressure curve s 35 specified at this time tl) as the final pressure value pe.

[0082] Advantageously, the determination of a respective pressure start value ps and / or a respective pressure end value pe described above is carried out for each of the pneumatic actuators 4, in each case in particular on the basis of the respective control signal 34 and the respective pressure profile s 35. Preferably, the valve device 3, in particular the control unit 11, is configured to generate a respective target pressure profile for each pneumatic actuator 4 on the basis of the respective pressure end value and the respective pressure start value.For example, the valve device 3 uses the pressure start value as the first target pressure value of the target pressure curve and / or the pressure end value as the last target pressure value of the target pressure curve and / or performs a calculation, for example an interpolation calculation and / or curve fitting calculation, to determine all or several (especially the remaining) target pressure values ​​of the target pressure curve based on the pressure start value and the pressure end value.

[0083] The following section will explain in more detail how a specific target pressure curve can be calculated.

[0084] Preferably, the valve device 3, in particular the control unit 11, generates a respective position-pressure mapping 23 for each pneumatic actuator based on the respective pressure end value (for example, the respective first pressure end value) and optionally the respective pressure start value (for example, the respective first pressure start value). By way of example, a respective position-pressure mapping 23 is generated, in particular calculated, for each pneumatic actuator 4 (and optionally for each direction of movement).

[0085] Figure 4 shows an example of a positional pressure

[0086] Figure 23 as a characteristic curve in a pressure-position-

[0087] Diagram. The position-pressure diagram 23 describes a relationship between the pressure p for actuating the respective pneumatic actuator and the position z of the respective actuator element 5. The position-pressure diagram 23, in particular the characteristic curve, can be linear or non-linear.

[0088] The position-pressure mappings 23 are expediently stored in a memory of the valve device 3, in particular the control unit 11, for example as characteristic curves, tables of values ​​and / or mathematical formulas. The position-pressure mappings 23, in particular the characteristic curves, tables of values ​​and / or mathematical formulas, are preferably model-based.

[0089] The following explanations of the position-print figure 23 apply expediently to several or all position-print figures 23.

[0090] Position-pressure mapping 23 maps a plurality of position values ​​z to a plurality of pressure values ​​p, in particular such that each position value z is assigned a corresponding pressure value p. For example, position-pressure mapping 23 assigns the initial pressure value ps to a first position value zel, which in particular describes the first end position. For example, position-pressure mapping 23 assigns the final pressure value pe to a second position value ze2, which in particular describes the second end position. Position values ​​between the first position value zel and the second position value ze2 are assigned pressure values ​​between the initial pressure value and the final pressure value.These pressure values, which can also be referred to as intermediate pressure values, are expediently calculated by the valve device 3, in particular by the control unit 11, for example by means of an interpolation calculation or a curve fitting calculation, in particular on the basis of the initial pressure value ps, final pressure value pe, first position value zel and second position value ze2. For example, the position-pressure mapping 23 is calculated as a characteristic curve (in particular a straight line or a curve of another shape) that passes through the two pairs of values ​​(ps , zel) and (pe , ze2 ).

[0091] The points shown in Figure 4 are intended to represent pairs of values ​​consisting of a pressure value p and an associated position value z, which are stored, for example, as a table of values ​​and / or as a characteristic curve in the control unit 11.

[0092] For each pneumatic actuator 4, it is expedient to calculate at least one respective position-pressure mapping 23.

[0093] The valve device 3, in particular the control 11, is expediently designed to convert a target position profile 24 into the target pressure profiles 25 using the position-pressure mappings 23.

[0094] The target position curve 24 is a time-dependent progression of a target position for the actuator elements 5. The target position curve 24 can also be described as a target position trajectory. The target position curve 24 comprises a plurality of position values ​​z. The target position curve 24 is, for example, rising, but can alternatively also be falling or have a different shape. For example, the target position curve 24 has a curved shape and / or a decreasing slope over time (for example, to achieve a smooth transition to the target position zp). The last position value z of the target position curve 24 is the target position zp.

[0095] The target position profile 24 is provided by the valve device 3, in particular the control 11, and in particular calculated.

[0096] Based on the target position profile 24 and the respective position-pressure mapping 23, the valve device 3, in particular the control 11, calculates a respective target pressure profile 25, in particular by converting each of the position values ​​z of the target position profile 24 according to the position-pressure mapping 23 into the respective assigned pressure value p, in particular by converting.

[0097] According to the target pressure profiles 25, the pneumatic actuators 4 are then controlled by the valve device 3, in particular the pressure regulator units 9, especially simultaneously, in order to achieve, for example, synchronous movement of the actuator elements 5. Preferably, the control signals 34 provided in this context are detected by the valve device 3 in order to be able to recognize the blockage state for each of the actuator elements 5.

Claims

Claims 1. Method for detecting a blockage state of at least one actuating section of a pneumatic system (1) for industrial automation, comprising at least one pneumatic actuator (4) and a valve device (3) having a pressure regulator unit (9) and serving to pneumatically actuate the pneumatic actuator (4) with an output pressure of the pressure regulator unit (9) in order to thereby set the actuating section in motion, comprising the steps: - Providing a target pressure profile (25) , - Performing pressure control of the output pressure according to the target pressure curve (25) in order to pneumatically actuate the pneumatic actuator (4), - Detection of a control signal (34) with which a valve unit (12) of the pressure control unit (9) is controlled as part of the pressure control, and - Detection of the blockage state based on the detected control signal (34) .

2. The method according to claim 1, wherein the actuating section serves to set an object in motion, and the blockage state is then present when the object, despite pneumatic actuation of the pneumatic actuator (4) and a resulting movement from the actuating section onto the The object cannot be set in motion by the applied driving force.

3. Method according to claim 2, wherein the object is a wafer (2) and the actuating section serves to lift the wafer (2) from a wafer support (17), and the blockage state is present when the wafer (2) cannot be lifted from the wafer support (17) despite pneumatic actuation of the pneumatic actuator (4) and a driving force thereby applied to the wafer (2) by the actuating section.

4. Method according to claim 3, wherein the wafer support (17) is part of a wafer holding device which holds the wafer (2) in a blocked state, in particular in a faulty state, and thereby prevents the wafer (2) from being lifted off.

5. Method according to claim 1, wherein the actuating section comprises an actuator element (5) and the blocking state is present when the actuator element (5) is in an end position in which it rests against an end stop.

6. Method according to claim 5, further comprising the steps: detecting a final pressure value (pe) with which the pneumatic actuator (4) is actuated when the actuator element (5) reaches the end position, and, based on the final pressure value (pe) , generating a position-pressure mapping (23) which describes a relationship between the output pressure and a position of the actuator element (5).

7. The method of claim 6, further comprising the step of: using the position-pressure mapping (23) by the valve device (3) to establish a target position for the actuator element at an output pressure for actuating the to implement pneumatic actuator (4) in order to move the actuator element (5) into the target position.

8. Method according to a preceding claim, wherein the blockage state is detected without the use of a position sensor for the actuating section.

9. Method according to a preceding claim, wherein the pneumatic system (1) is placed in a safety state in response to the detection of the blockage state.

10. Method according to one of the preceding claims, wherein a signal characteristic (37) is detected in the detected control signal (34) and the blocking state is detected on the basis of the detected signal characteristic (37).

11. Method according to one of the preceding claims, wherein the control signal (34) serves to adjust the size of a valve opening through which compressed air flows to or from a pressure chamber (6) of the pneumatic actuator (4), wherein the volume of the pressure chamber (6) changes when the actuating section is moved.

12. Method according to one of the preceding claims, wherein the blockage state is detected on the basis of a comparison of a signal profile of the detected control signal (34) with a reference signal profile.

13. Method according to one of the preceding claims, wherein the blockage state is detected taking into account a pressure signal profile, in particular the target pressure profile (25) and / or a detected actual pressure profile.

14. Method according to a preceding claim, wherein the pneumatic system (1) comprises several actuating sections, several pneumatic actuators (4) and several pressure regulator units (9), wherein each pressure regulator unit (9) serves to pneumatically actuate a respective pneumatic actuator (4) with its respective output pressure in order to thereby set a respective actuating section in motion, comprising the steps: - Performing a respective pressure control of the respective output pressure according to the target pressure curve (25) or a respective target pressure curve in order to pneumatically actuate the respective pneumatic actuator (4), - Detection of a respective control signal (34) with which a respective valve unit (12) of the respective pressure regulator unit (9) is controlled within the framework of the respective pressure regulation, and - Detection of a respective blockage state based on the respective detected control signal (34) .

15. Pneumatic system (1) for industrial automation, comprising at least one pneumatic actuator (4) and a valve device (3) having a pressure regulator unit (9) with a valve unit (12) and configured to perform pressure control with the pressure regulator unit (9) according to a setpoint pressure profile (25) in order to pneumatically actuate the pneumatic actuator (4) in order to thereby set an actuating section of the pneumatic system (1) in motion, wherein the valve device (3) is further configured to detect a control signal (34) with which the valve unit (12) is actuated within the framework of pressure control, and to detect a blocking state of the to identify the actuating section based on the detected control signal (34).

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