Method for controlling a piezo valve device, control device and fluidic system

Abstract

Method for controlling, in particular pressure controlling, a piezo valve device (30), comprising the steps of: - calculating (S2) a control error integral signal (IS) that represents a time integral of a control error (RF) of the control of the piezo valve device (30), - adapting (S4), based on the control error integral signal (IS), at least one control opening voltage value (RW1, RW2) that defines an opening voltage value of a piezo valve (6) of the piezo valve device (30) within the control, and - using the adapted at least one control opening voltage value (RW1, RW2), providing (S5) at least one control voltage (AS1, AS2) for controlling the piezo valve (6) within the control, wherein the at least one control opening voltage value (RW1, RW2) is adapted such that the control error integral signal (IS) represents a predetermined oscillation signal shape. assumesin particular a vibration signal shape of a preferably symmetrical triangular oscillation.

Description

[0001] The invention relates to a method for controlling a piezo valve device.

[0002] The control system is preferably a pressure control system, for example, a control of the output pressure of the piezoelectric valve assembly. The pressure control system is, for example, the control of the fluid pressure in a pressure chamber that is vented and / or aerated via the piezoelectric valve assembly. The piezoelectric valve assembly has at least one piezoelectric valve. The piezoelectric valve has an opening voltage value. The opening voltage value is the minimum voltage required to actuate the piezoelectric valve in order for it to begin opening. The opening voltage value of the piezoelectric valve is also referred to as the actual or real opening voltage value.

[0003] Typically, the actual opening voltage of a piezoelectric valve changes over time, for example, due to aging, temperature changes, applied differential pressure, and / or the piezoelectric effect. A change in the actual opening voltage can lead to a deterioration in control performance. Control performance includes, for example, control accuracy, control bandwidth (e.g., speed), and / or control fluid consumption.

[0004] One object of the invention is to provide a flexibly applicable method for controlling a piezo valve device, with which high control performance can be achieved even with a changing real opening voltage value.

[0005] The problem is solved by a method according to claim 1. The method serves for the control, in particular the pressure control, of a piezoelectric valve device. The method comprises the steps of: calculating a control error integral signal that represents a time integral of a control error of the piezoelectric valve device's control; adjusting, based on the control error integral signal, at least one control opening voltage value that defines an opening voltage value of a piezoelectric valve of the piezoelectric valve device within the control system; and, using the control opening voltage value, providing a control voltage for controlling the piezoelectric valve within the control system.

[0006] In this method, a control opening voltage value is used for regulation. This control opening voltage value defines an opening voltage value for the piezoelectric valve within the control system. The opening voltage value defined within the control system—i.e., the control opening voltage value—is also referred to as the simulated or imaginary opening voltage value. The control opening voltage value used within the control system does not necessarily have to be exactly the same value as the actual opening voltage value of the piezoelectric valve. Preferably, the control opening voltage value is chosen to be lower than the actual opening voltage value of the piezoelectric valve. Advantageously, changes in the actual opening voltage value can be simulated within the control system using the control opening voltage value.By using the control opening voltage value during the control process, the control system can be adapted to the actual opening voltage value, and especially to changes in the actual opening voltage value. In this way, high control performance can be achieved.

[0007] Typically, the actual opening voltage value of the piezoelectric valve cannot be directly determined during operation. For example, a direct determination of the actual opening voltage value is not possible, or a direct determination of the opening voltage value would require a special (specifically directed for the determination) control of the piezoelectric valve device, for which the normal operation of the piezoelectric valve device would have to be interrupted.

[0008] The method according to the invention is based on the understanding that the actual opening voltage value of the piezoelectric valve affects the control error integral signal – i.e., the time integral of the control error of the control system. In particular, a change in the actual opening voltage value causes a change in the control error integral signal. Consequently, the control opening voltage value can be adjusted based on the control error integral signal, specifically in such a way that the control opening voltage value replicates a change in the actual opening voltage value. In this way, the control opening voltage value can be adjusted according to the actual opening voltage value without having to directly determine the actual opening voltage value. This preferably allows the control opening voltage value to be adjusted during operation.The method can therefore be used flexibly - especially for applications where pausing the control for the purpose of adjusting the control opening voltage value is not possible or not desired.

[0009] Advantageous further training is the subject of the sub-claims.

[0010] The invention further relates to a control device for regulating, in particular pressure regulating, a piezo valve device, wherein the control device is configured to calculate a control error integral signal that represents a time integral of a control error of the piezo valve device's regulation, to adjust at least one control opening voltage value on the basis of the control error integral signal, which describes an opening voltage value of a piezo valve of the piezo valve device within the regulation, and, using the control opening voltage value, to provide a control voltage for controlling the piezo valve within the regulation.

[0011] Preferably, the control device is designed in accordance with the method for controlling the piezo valve device and / or is used to carry out the method.

[0012] The invention further relates to a fluidic system comprising the control device and the piezo valve device.

[0013] Further exemplary details and embodiments are explained below with reference to the figures. Fig. 1 a schematic representation of a fluidic system, Fig. 2 a block diagram of a control loop, Fig. 3 a block diagram of a controller, Fig. 4. A diagram illustrating a real opening voltage value of a piezoelectric valve, Fig. 5. A diagram illustrating different areas of operation of the regulation. Fig. 6 a diagram showing the time course of a control error integral signal in a first working area, Fig. 7 a diagram showing the time course of a control error integral signal in a second working area Fig. 8 a flowchart of a procedure for controlling a piezo valve device.

[0014] The Fig. Figure 1 shows a fluidic system 10 comprising a control device 20 and a piezoelectric valve assembly 30. By way of example, the fluidic system 10 further comprises a fluidic actuator 40. Preferably, the fluidic system 10 also comprises a pressure fluid source 50 and / or a pressure fluid sink 60. The pressure fluid sink 60 is, for example, the environment of the piezoelectric valve assembly 30, in particular the atmosphere. Preferably, the fluidic system 10 is a pneumatic system.

[0015] The fluidic system 10, in particular the control device 20, the piezo valve device 30 and / or the fluidic actuator 40, is suitably designed for industrial automation. For example, an industrial plant is provided that includes the fluidic system 10.

[0016] The fluidic system 10 serves in particular as an exemplary application environment for the controller device 20. The controller device 20 can also be provided on its own – i.e., in particular without the piezo valve device 30 and / or without the fluidic actuator 40.

[0017] The fluidic actuator 40 is, for example, a pneumatic actuator. Preferably, the fluidic actuator 40 is a drive cylinder, in particular a pneumatic drive cylinder.

[0018] The fluidic actuator 40 comprises at least one pressure chamber to which pressurized fluid, in particular compressed air, can be supplied and / or discharged by means of the piezoelectric valve assembly 30. By way of example, the fluidic actuator 40 comprises a first pressure chamber 1 and / or a second pressure chamber 2. By way of example, the first pressure chamber 1 is fluidically connected to a first working outlet 3 of the piezoelectric valve assembly 30. Advantageously, pressurized fluid, in particular compressed air, can be supplied and / or discharged to the first pressure chamber 1 via the first working outlet 3. By way of example, the second pressure chamber 2 is fluidically connected to a second working outlet 4 of the piezoelectric valve assembly 30. Advantageously, pressurized fluid, in particular compressed air, can be supplied and / or discharged to the second pressure chamber 2 via the second working outlet 4.

[0019] By way of example, the fluidic actuator 40 comprises an actuator element 5, which is designed in particular as a piston arrangement. The actuator element 5 can be positioned by pressurizing the first pressure chamber 1 and / or the second pressure chamber 2 with pressurized fluid.

[0020] The piezoelectric valve assembly 30 comprises the first working outlet 3. The piezoelectric valve assembly 30 comprises at least one piezoelectric valve 6 through which pressurized fluid, in particular compressed air, can be discharged at the first working outlet 3 or released (into the piezoelectric valve assembly 30). By way of example, the piezoelectric valve assembly 30 comprises a first piezoelectric valve 6A through which a fluidic connection between the first working outlet 3 and the pressurized fluid source 50 can be established or interrupted, or its degree of opening can be adjusted. By way of example, the piezoelectric valve assembly 30 comprises a second piezoelectric valve 6B through which a fluidic connection between the first working outlet 3 and the pressurized fluid sink 60 can be established or interrupted, or its degree of opening can be adjusted.

[0021] By way of example, the piezoelectric valve assembly 30 comprises the second working outlet 4. By way of example, the piezoelectric valve assembly 30 comprises a third piezoelectric valve 6C, via which a fluidic connection of the second working outlet 4 with the pressure fluid source 50 can be established or interrupted, or its degree of opening can be adjusted. By way of example, the piezoelectric valve assembly 30 comprises a fourth piezoelectric valve 6D, via which a fluidic connection of the second working outlet 4 with the pressure fluid sink 60 can be established or interrupted, or its degree of opening can be adjusted.

[0022] As an example, the piezoelectric valve assembly 30 includes a pressure fluid inlet 7 for connection to the pressure fluid source 50. The first piezoelectric valve 6A is connected, as an example, between the pressure fluid inlet 7 and the first working outlet 3. The third piezoelectric valve 6C is connected, as an example, between the pressure fluid inlet 7 and the second working outlet 4.

[0023] As an example, the piezoelectric valve assembly 30 includes a pressure fluid output 8 for connection to the pressure fluid sink 60. The second piezoelectric valve 6B is, as an example, connected between the pressure fluid output 8 and the first working output 3. The fourth piezoelectric valve 6D is, as an example, connected between the pressure fluid output 8 and the second working output 4.

[0024] The piezo valve 6 is part of a bridge circuit of the piezo valve device 30. Preferably, the piezo valves 6A, 6B, 6C and 6D form a bridge circuit, in particular a full bridge.

[0025] Each piezo valve 6 is expediently designed as a 2 / 2-way valve, in particular as a 2 / 2-way proportional valve. Each piezo valve 6 has a respective valve element 9 by which the respective opening degree of the respective piezo valve 6 can be adjusted, in particular proportionally.

[0026] The fluidic system 10, in particular the piezoelectric valve assembly 30, expediently comprises a pressure sensor assembly for detecting one or more fluid pressures of the fluidic system 10. By way of example, the pressure sensor assembly comprises a first pressure sensor 11 for detecting a first output pressure of the first working outlet 3. The first output pressure expediently corresponds to the pressure in the first pressure chamber 1. By way of example, the pressure sensor assembly comprises a second pressure sensor 12 for detecting a second output pressure of the second working outlet 4. The second output pressure expediently corresponds to the pressure in the second pressure chamber 2. By way of example, the pressure sensor assembly comprises a third pressure sensor 13 for detecting an input pressure of the pressure fluid input 7 and / or a fourth pressure sensor 14 for detecting an output pressure at the pressure fluid outlet 8.

[0027] The control device 20 is configured to perform a control, in particular a pressure control, of the piezo valve device 30. In particular, the control device 20 is configured to perform a first pressure control of the first output pressure and / or a second pressure control of the second output pressure.

[0028] The control device 20 is preferably configured to perform the first pressure control of the first output pressure based on the first output pressure detected by the first pressure sensor 11 (as actual output pressure) and a predetermined target output pressure. The control device 20 is preferably configured to control, for the control, in particular the first pressure control, the first piezo valve 6A with a first control voltage AS1, and / or the second piezo valve 6B with a second control voltage AS2, in order to adjust the opening degree of the respective piezo valve 6A, 6B, so that the actual output pressure is changed towards the target output pressure.

[0029] As an example, the control system uses the first piezo valve 6A to supply pressure fluid into the first pressure chamber 1 and the second piezo valve 6B to drain pressure fluid from the first pressure chamber 1.

[0030] The second pressure control of the second output pressure is achieved by controlling the third piezo valve 6C (with a third control voltage) and the fourth piezo valve 6D (with a fourth control voltage). The second pressure control is expediently carried out analogously to the first pressure control of the first output pressure.

[0031] The control device 20 expediently comprises a processing unit 15, in particular a microcontroller, on which a control program is preferably executed. The control device 20 is configured to calculate the control voltages, in particular the first control voltage AS1 and / or the second control voltage AS2, for the control of the piezo valve device using the control program, particularly on the basis of the first output pressure and / or the target output pressure.

[0032] The Fig. Figure 2 shows a block diagram of a control loop for the control of the piezo valve device 30. The control loop serves in particular to control the first output pressure.

[0033] The control loop includes a controller 16, which is provided by the controller device, for example, by the controller program. The controller 16 receives a setpoint SW, in particular from a higher-level controller, for example, a programmable logic controller (PLC). The setpoint SW is, for example, the target output pressure. The controller 16 also receives an actual value IW, for example, the actual value of the first output pressure detected by the first pressure sensor 11. Based on the setpoint SW and the actual value IW, the controller 16 calculates the first control voltage AS1 and the second control voltage AS2, such that the actual value IW is changed towards the setpoint SW.

[0034] The control loop comprises the piezo valve assembly 30, in particular the first piezo valve 6A and / or the second piezo valve 6B. The piezo valve assembly 30 is controlled by the first control voltage AS1 and / or the second control voltage AS2 and, in response to this control, provides a first mass flow MS1 of pressure fluid (from the pressure fluid source 50) to the first working output 3 via the first piezo valve 6A and / or provides a second mass flow MS2 away from the first working output (towards the pressure fluid sink 60) via the second piezo valve 6B.

[0035] The control loop further comprises a controlled system 17, which is formed in particular by the working volume present at the first working outlet 3. The working volume includes, for example, the volume of the first pressure chamber 1 and / or the volume of a fluidic connection between the working outlet 3 and the first pressure chamber 1. The working volume is the volume that is filled with the pressure fluid via the first working outlet 3 and in which the first outlet pressure prevails.

[0036] The first mass current MS1 and / or the second mass current MS2 is supplied to the control loop 17, on the basis of which the actual value IW is set, which is fed back to the controller 16.

[0037] The Fig. Figure 3 shows a block diagram of an exemplary implementation of the controller 16.

[0038] Preferably, the controller 16 comprises a controller section 18, which is implemented as a PI element. The term PI element stands for proportional-integrating element. The PI element can also be referred to as a PI controller. Optionally, the controller section 18 can be implemented as a PID element. The term PID element stands for proportional-integrating-differential element. The PID element can also be referred to as a PID controller.

[0039] Controller section 18 is configured to calculate a pressure fluid supply signal DZS and / or a pressure fluid discharge signal DAS based on the setpoint SW and the actual value IW. The pressure fluid supply signal DZS forms the basis of the first control voltage AS1, and the pressure fluid discharge signal DAS forms the basis of the second control voltage AS2.

[0040] The controller section 18 includes a control error element 19 for calculating a control error RF based on the setpoint SW and the actual value IW. For example, the control error element 19 is configured to calculate the control error RF as the difference between the setpoint SW and the actual value IW.

[0041] Controller section 18 includes, as an example, a P-element 21. The P-element 21 can also be referred to as a proportional element. The P-element 21 is configured to calculate a proportional signal PS based on the control error RF. For example, the P-element 21 is configured to multiply the control error RF by a coefficient to calculate the proportional signal PS.

[0042] The control device 20, in particular the control section 18, is preferably configured to calculate a control error integral signal IS, which represents a time integral of the control error RF of the control of the piezo valve device 30.

[0043] Controller section 18 includes, as an example, an integral element 22. The integral element 22 can also be referred to as an integrating element. The integral element 22 is configured to calculate the control error integral signal IS based on the control error RF. For example, the integral element 22 is configured to integrate the control error RF over time to calculate the control error integral signal IS. The control error integral signal IS represents an integral component (integrating component = integral term) of the PI element.

[0044] Controller section 18 is configured to calculate the pressure fluid supply signal DZS and / or the pressure fluid discharge signal DAS based on the proportional signal PS and the control error integral signal IS. Controller section 18 includes, by way of example, a summing element 23 configured to add the proportional signal PS and the control error integral signal IS to obtain a summing signal SS.

[0045] The controller section 18 further includes, by way of example, a separator 24 configured to calculate the pressure fluid supply signal DZS and / or the pressure fluid discharge signal DAS based on the summation signal SS. For example, if the summation signal SS is positive, the separator 24 sets the pressure fluid discharge signal DAS to zero (or to a value less than zero) and adjusts the pressure fluid supply signal DZS according to, and in particular proportionally to, the magnitude of the summation signal SS. For example, if the summation signal SS is negative, the separator 24 sets the pressure fluid supply signal DZS to zero (or to a value less than zero) and adjusts the pressure fluid supply signal DAS according to, and in particular proportionally to, the magnitude of the summation signal SS.

[0046] The controller 16 is designed to provide the first control voltage AS1 based on the pressure fluid supply signal DZS and / or to provide the second control voltage AS2 based on the pressure fluid discharge signal DAS.

[0047] The controller 16 further comprises an adaptation section 25. The adaptation section 25 serves to provide the first control voltage AS1 such that it is adapted to a first real opening voltage value OW1, in particular to a change in the first real opening voltage value OW1. Advantageously, the adaptation section 25 serves to provide the second control voltage AS2 such that it is adapted to a second real opening voltage value OW2, in particular to a change in the second real opening voltage value OW2.

[0048] The first real opening voltage value OW1 is the minimum voltage value that the first control voltage AS1 must have for the first piezo valve 6A to begin opening. The second real opening voltage value OW2 is the minimum voltage value that the second control voltage AS2 must have for the second piezo valve 6B to begin opening.

[0049] The adaptation section 25 is configured to provide the first adaptation voltage AS1 based on the pressure fluid supply signal DZS and the control error integral signal IS. The adaptation section 25 is configured to provide the second adaptation voltage AS2 based on the pressure fluid discharge signal DAS and the control error integral signal IS.

[0050] Preferably, the controller 20, in particular the adaptation section 25, is configured to adapt at least one control opening voltage value (preferably both control opening voltage values ​​RW1, RW2) based on the control error integral signal IS. Preferably, each control opening voltage value RW1, RW2 defines a respective opening voltage value of a respective piezo valve 6 of the piezo valve assembly 30 within the control system (in particular within the controller program). The controller, in particular the adaptation section 25, is configured to provide at least one control voltage for controlling the piezo valve 6 within the framework of the control system, using the at least one control opening voltage value (preferably both control opening voltage values ​​RW1, RW2).

[0051] The term "at least one control opening voltage value" refers in particular to the first control opening voltage value RW1 and the second control opening voltage value.

[0052] Preferably, the adaptation section 25 comprises an opening voltage value calculation element 26 configured to calculate the first control opening voltage value RW1 and / or the second control opening voltage value RW2 based on the control error integral signal IS. The first control opening voltage value RW1 is, for example, a first offset value that is added to the pressure fluid supply signal DZS to obtain the first drive voltage AS1. The first control opening voltage value RW1 can also be referred to as the first offset value or the first offset voltage. The second control opening voltage value RW2 is, for example, a second offset value that is added to the pressure fluid discharge signal DAS to obtain the second drive voltage AS2. The second control opening voltage value RW2 can also be referred to as the second offset value or the second offset voltage.

[0053] Preferably, the opening voltage value calculation element 26 is configured to check whether a safety criterion for performing the adjustment of the at least one control opening voltage value is met. In particular, the opening voltage value calculation element 26 is configured to perform the adjustment of the at least one control opening voltage value in response to the fact that the safety criterion is met.

[0054] As an example, the control error RF is fed to the opening voltage value calculation element 26, and the opening voltage value calculation element 26 checks, based on the control error RF, whether the safety criterion is met. The safety criterion is met, for example, if the control error RF indicates a steady state of the control system, for example, if it is smaller than a predetermined threshold and / or constant.

[0055] For example, the adaptation section 25 includes a first summing element 27 that adds the first control opening voltage value RW1 to the pressure fluid supply signal DZS to obtain the first control voltage AS1. For example, the adaptation section 25 includes a second summing element 28 that adds the second control opening voltage value RW2 to the pressure fluid discharge signal DAS to obtain the second control voltage AS2.

[0056] The control device 20 is designed to adapt the control, in particular the provision of the first control voltage AS1 and / or the second control voltage AS2, to a changing actual opening voltage value of the respective piezo valve 6 by means of the control opening voltage values ​​RW1 and / or RW2. During operation of the piezo valve 6, the actual opening voltage value typically changes over time.

[0057] The Fig. Figure 4 shows a diagram illustrating the actual opening voltage value of a piezoelectric valve 6. The following explanations conveniently apply to each piezoelectric valve 6A, 6B, 6C, and / or 6D. The horizontal axis of the diagram represents the control voltage of the piezoelectric valve 6, and the vertical axis represents the degree of opening of the piezoelectric valve 6. The diagram includes a first characteristic curve K1, which shows the degree of opening of the piezoelectric valve 6 as a function of the control voltage at a first time point. According to the first characteristic curve K1, the piezoelectric valve 6 begins to open at an actual opening voltage value OWt1; that is, at a control voltage greater than the actual opening voltage value OWt1, the piezoelectric valve 6 provides a degree of opening greater than zero, and at a control voltage less than the actual opening voltage value OWt1, the piezoelectric valve 6 provides a degree of opening equal to zero.

[0058] The diagram includes a second characteristic curve K2, which shows the opening degree of the piezoelectric valve 6 as a function of the control voltage at a second time point. The second characteristic curve exhibits a real opening voltage value OWt2. In the second characteristic curve K2, the real opening voltage value has changed compared to the first characteristic curve K1; for example, the real opening voltage value OWt2 is greater than the real opening voltage value OWt1.

[0059] The Fig. Figure 5 shows a diagram illustrating different operating ranges of the control of the piezoelectric valve device 30. The first control voltage AS1 is plotted on the right half of the horizontal axis, and the second control voltage AS2 is plotted on the left half. The first control voltage AS1 increases in the right direction, and the second control voltage AS2 increases in the left direction. The mass flow at the first pressure output 3 is plotted on the vertical axis.

[0060] The diagram shows the first real opening voltage value OW1 of the first piezoelectric valve 6A and the second real opening voltage value OW2 of the second piezoelectric valve 6B. The operating range between the first real opening voltage value OW1 and the second real opening voltage value OW2 is the first operating range and is also referred to as the dead zone TZ. The range outside the first operating range is referred to as the second operating range.

[0061] The diagram shows a characteristic curve KL, which indicates how the mass current present at the first pressure output 3 depends on the setting of the control opening voltage values ​​RW1, RW2 in relation to the actual opening voltage values ​​OW1, OW2, especially in a state in which the control provided by the control device 20 actually does not require any mass current at the first pressure output 3.

[0062] Preferably, the controller device 20 is configured to adjust both control opening voltage values ​​RW1 and RW2 so that they lie within the dead zone TZ. Preferably, the controller device 20 adjusts the first control opening voltage value RW1 so that it is smaller than the first actual opening voltage value OW1 and / or adjusts the second control opening voltage value RW2 so that it is smaller than the second actual opening voltage value OW2.

[0063] If both control opening voltage values ​​RW1, RW2 are in the dead zone TZ, it can be prevented that pressure fluid is unnecessarily consumed during control.

[0064] Preferably, the controller device 20 is configured to adjust the two control opening voltage values ​​RW1, RW2 such that the control error integral signal IS assumes a predetermined oscillation waveform, in particular an oscillation waveform of a preferably symmetrical triangular waveform. For this purpose, the controller device 20 expediently performs a waveform analysis, for example a Fourier transform, of the control error integral signal IS, particularly during the adjustment of the two control opening voltage values ​​RW1, RW2, preferably continuously, and preferably performs the adjustment based on the waveform analysis.

[0065] The Fig. Figure 6 shows a diagram with a time course of the control error integral signal IS in the first operating range – i.e., in the dead zone TZ. Time is plotted on the horizontal axis, and the value of the control error integral signal IS is plotted on the vertical axis. The controller device 20 is expediently designed to adjust the two control opening voltage values ​​RW1, RW2 such that the control error integral signal IS corresponds to the value in the Fig. The signal waveform shown in Figure 6 is also referred to as the dead zone waveform. The control error integral signal IS (with the dead zone waveform) has a periodic signal pattern. For example, the control error integral signal IS (with the dead zone waveform) has an oscillatory waveform of a triangular oscillation. The control error integral signal IS (with the dead zone waveform) exhibits a plurality of alternating positive peaks 29 and negative peaks 31, which are conveniently connected to each other by straight signal segments. The control error integral signal IS has positive values ​​at the positive peaks 29 and negative values ​​at the negative peaks 31.

[0066] The value of a positive peak 29 of the control error integral signal IS shall be referred to as the positive actual amplitude 32 of the control error integral signal. The value (or magnitude) of a negative peak 31 of the control error integral signal shall be referred to as the negative actual amplitude 33 of the control error integral signal.

[0067] Preferably, the control device 20 is configured to adjust the two control opening voltage values ​​RW1, RW2 such that the magnitude of the positive actual amplitude 32 is equal to the magnitude of the negative actual amplitude 33. This means that the oscillation, in particular the triangular oscillation, is symmetrical.

[0068] The Fig. Figure 7 shows a graph with a time course of the control error integral signal IS in the second operating range – i.e., outside the dead zone. Time is plotted on the horizontal axis, and the value of the control error integral signal IS is plotted on the vertical axis.

[0069] The control error integral signal IS has a periodic signal waveform. For example, the control error integral signal IS has an oscillatory waveform of a sinusoidal oscillation. The control error integral signal IS in the second operating range is continuously positive and, for example, never negative. For example, the control error integral signal IS oscillates around a positive mean value of 34.

[0070] The Fig. Figure 8 shows a flowchart of a method for controlling the piezo valve device 30. The control is, by way of example, a pressure control, in particular a pressure control of the first output pressure at the first working outlet 3.

[0071] The procedure begins with an optional step S1, in which the control process is initiated, specifically before the adjustment of the at least one control opening voltage value has taken place. The term "at least one control opening voltage value" refers in particular to the first control opening voltage value RW1 and the second control opening voltage value RW2. The adjustment of the at least one control opening voltage value then expediently takes place during the control process – i.e., during operation. During the control process, the controller 20 regulates an actual value IW (in particular, the first output pressure) to a setpoint SW (in particular, a predetermined setpoint output pressure) by actuating the piezoelectric valve device 30. The control process initially occurs with an unadjusted at least one control opening voltage value.

[0072] The procedure continues with step S2. In step S2, the control error integral signal IS is calculated, which represents a time integral of the control error RF of the piezo valve device 30. Advantageously, the controller 20 calculates the control error integral signal IS in step S2, on the basis of which the adjustment of at least one control opening voltage value is then performed. Advantageously, the controller 20 calculates the control error integral signal IS already within the scope (and for the purpose) of controlling the piezo valve device 30, and / or provides, for example, the control voltages AS1, AS2 based on the control error integral signal IS calculated in step S2.

[0073] Optionally, the method includes a step S3 in which the controller 20 checks whether a safety criterion for adjusting the at least one control opening voltage value is met, wherein the adjustment (in the subsequent step S4) is carried out in response to the fact that the safety criterion is met. Advantageously, the controller 20 continues adjusting the at least one control opening voltage value in response to the fact that the safety criterion is met. Advantageously, the controller 20 does not continue adjusting the at least one control opening voltage value as long as the safety criterion is not met.

[0074] The safety criterion is fulfilled, for example, by ensuring a steady state of control for the piezo valve device 30. For example, the controller 20 checks, as a safety criterion, whether the control error RF is constant and / or less than a predetermined threshold. Preferably, the controller 20 checks, as a safety criterion, whether the setpoint SW and / or the actual value IW are constant.

[0075] Advantageously, the control device 20 only continues with the procedure if the safety criterion is met, i.e., in particular in response to the fact that one, several or all of the aforementioned tests are passed.

[0076] By checking the safety criterion, the controller device 20 can ensure that the adjustment of the at least one control opening voltage value takes place in a state in which the adjustment does not impair the control that continues to run during the adjustment.

[0077] The procedure expediently continues with step S4, in which, based on the control error integral signal IS of the least significant control opening voltage value, this value defines an opening voltage value of a piezo valve 6 of the piezo valve assembly 30 within the control system. In particular, the controller 20 adjusts the first control opening voltage value RW1 and / or the second control opening voltage value based on the control error integral signal IS.

[0078] Preferably in step S4, the at least one control opening voltage value (preferably both control opening voltage values ​​RW1, RW2) is adjusted such that the control error integral signal IS assumes a predetermined oscillation signal shape, in particular an oscillation signal shape of a preferably symmetrical triangular oscillation.

[0079] Preferably, in step S4, the at least one control opening voltage value is adjusted such that it is smaller than the actual opening voltage value of the respective piezo valve 6. For example, the first control opening voltage value RW1 is adjusted such that it is smaller than the actual opening voltage value OW1 of the first piezo valve 6A. For example, the second control opening voltage value RW2 is adjusted such that it is smaller than the actual opening voltage value OW2 of the second piezo valve 6B.

[0080] Preferably, the calculation S3 of the control error integral signal IS and / or the adjustment S4 of the at least one control opening voltage value (in particular both control opening voltage values ​​RW1, RW2) is carried out during the control, in particular the pressure control, of the piezo valve device 30. The control, in particular the pressure control, of the piezo valve device 30 preferably comprises a PI control or a PID control, and the control error integral signal IS is expediently an integral component of the PI control or the PID control.

[0081] Preferably, during the adjustment in step S4, the first control opening voltage value RW1 is adjusted first, while the second control opening voltage value RW2 is not adjusted. Only after the first control opening voltage value RW1 has been adjusted is the second control opening voltage value RW2 adjusted. Preferably, after the first control opening voltage value RW1 has been adjusted, the second control opening voltage value RW2 is adjusted together (especially simultaneously) with a further adjustment of the first control opening voltage value RW1.

[0082] For example, step S4 includes a first substep S41 in which the controller device 20 first adjusts one of the two control opening voltage values ​​RW1, RW2 and expediently does not yet adjust the other of the two control opening voltage values ​​RW1, RW2.

[0083] The controller device 20 performs the first substep S41 in particular in response to the fact that the control is in the second operating range - i.e. outside the dead zone TZ - and / or on the basis of the oscillation signal shape of the control error integral signal IS, in particular in response to the fact that the control error integral signal IS has an oscillation signal shape other than a triangular oscillation, for example a sinusoidal shape.

[0084] In response to the fact that the control is already in the first operating range, the control device 20 does not execute substep S41 (and preferably substep S42) and proceeds directly to substep S43.

[0085] Advantageously, the controller device 20 reduces one of the two control opening voltage values ​​RW1, RW2 at the first substep S41 and advantageously keeps the other of the two control opening voltage values ​​RW1, RW2 constant.

[0086] For example, in substep S41, the controller device 20 first adjusts the first control opening voltage value RW1 (in particular by decreasing it) and does not adjust the second control opening voltage value RW2 during this time. The controller device 20 performs this adjustment in particular in response to the fact that the control error integral signal has a negative mean value and / or the control error integral signal is continuously negative and / or the control error integral signal has a waveform other than a triangular waveform, for example, a sinusoidal waveform.

[0087] Advantageously, the controller device 20 checks in substep S41 during the reduction of the first control opening voltage value RW1 whether (with control running) the mean value of the control error integral signal IS decreases and, in response to this, continues the reduction of the first control opening voltage value RW1 until the mean value is equal to zero or until the mean value is no longer reduced.

[0088] In response to the fact that the mean value does not decrease during the reduction of the first control opening voltage value RW1, the control device 20 stops the reduction of the first control opening voltage value RW1 and instead increases the second control opening voltage value RW2 until the mean value is zero or until the mean value is no longer reduced.

[0089] Alternatively, in substep S41, the controller 20 first adjusts the second control opening voltage value RW2 (in particular by decreasing it) and does not adjust the first control opening voltage value RW1 during this process. The controller 20 performs this adjustment particularly in response to the fact that the control error integral signal has a positive mean value and / or the control error integral signal is continuously positive and / or the control error integral signal exhibits a waveform other than a triangular waveform, for example, a sinusoidal waveform.

[0090] Advantageously, the controller device 20 checks in substep S41 during the reduction of the second control opening voltage value RW2 whether (with control running) the mean value of the control error integral signal IS increases and, in response to this, continues the reduction of the second control opening voltage value RW2 until the mean value is equal to zero or until the mean value is no longer increased.

[0091] In response to the fact that the mean value does not increase during the reduction of the second control opening voltage value RW2, the control device 20 stops the reduction of the second control opening voltage value RW2 and instead increases the first control opening voltage value RW21 until the mean value is zero or until the mean value is no longer increased.

[0092] The method continues with substep S42, in which the controller device adjusts the first control opening voltage value RW1 together with the second control opening voltage value RW2 (in particular simultaneously), in particular reduces it, preferably until the control error integral signal IS has a triangular waveform as an oscillation signal shape and / or until the control is in the first operating range.

[0093] The procedure continues with substep S43, in which the first control opening voltage value RW1 and / or the second control opening voltage value RW2 are adjusted so that the control error integral signal IS has a symmetrical triangular waveform as its oscillation signal shape.

[0094] Preferably, at least one control opening voltage value is adjusted such that an actual amplitude of the control error integral signal IS equals a target amplitude. For example, the first control opening voltage value RW1 is adjusted based on the positive actual amplitude 32 of the control error integral signal IS and / or the second control opening voltage value RW2 is adjusted based on the negative actual amplitude 33 of the control error integral signal IS. For example, the first control opening voltage value RW1 is adjusted such that the positive actual amplitude 32 is equal to a (specified) positive target amplitude of the control error integral signal IS and / or the second control opening voltage value RW2 is adjusted such that the negative actual amplitude 33 is equal to a (specified) negative target amplitude of the control error integral signal IS.The positive target amplitude and / or the negative target amplitude are expediently calculated by the controller device 20 and / or specified externally, for example by a user input or by the higher-level control system.

[0095] The procedure continues with step S5. In step S5, using the adapted at least one control opening voltage value, at least one control voltage is provided to control the piezo valve 6 within the framework of the control, in particular the pressure control, of the piezo valve device 30. By way of example, in step S5, the controller 20 provides the first control voltage AS1 using the adapted first control opening voltage value RW1 and the second control voltage AS2 using the adapted second control opening voltage value RW2. In step S5, the controller 20 performs the control of the piezo valve device 30 using the first control opening voltage value RW1 and the second control opening voltage value RW2.

[0096] Preferably, during the control of the piezo valve device 30, the control device continuously performs further adjustments of the first control opening voltage value RW1 and / or the second control opening voltage value RW2, in particular as explained above on the basis of the positive actual amplitude 32 and / or the negative actual amplitude 33.

[0097] Further exemplary details will be explained below.

[0098] The controller device 20 is preferably configured to execute an adaptation and / or identification algorithm in which the adjustment, in particular the shift, of the control opening voltage values ​​RW1, RW2 described above is carried out, particularly during operation and / or at the start. Advantageously, the controller device 20 identifies a change in the actual opening voltage values ​​OW1, OW2 and compensates for this by adjusting the control opening voltage values ​​RW1, RW2, particularly during operation and / or at the start.

[0099] An adjustment during operation means, in particular, that an application for which the fluidic system 10 is used is running as intended (especially during the control of the piezo valve device 30) and that the adjustment of the control opening voltage values ​​RW1, RW2 takes place during this time. Specifically, the adjustment does not stop the application and / or does not change any controlled variable, such as the first output pressure, in a way that would impair or disrupt the application.

[0100] An initial adjustment means that the control opening voltage values ​​in a production line or in the field are adjusted once by a user (for example, during commissioning) by means of a trigger, in particular, identified. This process can be carried out via external triggering (for example, by an electrical signal or data bus) or automatically when a valve starts.

[0101] Preferably, in the fluidic system 10, the actual mass flow at the first working output 3 is not measured and / or not used for adjusting the control opening voltage values ​​RW1, RW2.

[0102] It is advantageous to measure the pressure at the first working output 3 and use it for adjusting the control opening voltage values ​​RW1, RW2.

[0103] Preferably, the first control voltage AS1 and the second control voltage AS2 can be specified independently of each other.

[0104] Preferably, the system operates in phases with a constant setpoint SW and a constant actual value IW. Advantageously, the adjustment of the control opening voltage values ​​RW1 and RW2 takes place in one of these phases.

[0105] The control device 20 is expediently designed to provide control of the piezo valve device 30 using a control algorithm. The control algorithm preferably comprises a PI controller and the adaptation algorithm, which adjusts the control opening voltage values.

[0106] The adaptation algorithm optionally uses characteristic values ​​derived from the time-dependent behavior of the integral component (i.e., the control error integral signal IS), the proportional component (i.e., the proportional signal PS), the manipulated variable (in particular, the first control voltage AS1 and / or the second control voltage AS2), and / or the control error RF, and / or other measured and / or calculated values, to adjust the control opening voltage values ​​RW1 and RW2. These characteristic values ​​can include, in particular: amplitudes, average values, symmetries, Fourier and correlation analyses, periods, and waveforms (sinusoidal, triangular, rectangular).

[0107] The control opening voltage values ​​RW1, RW2 are expediently adjusted so that a triangular oscillation (especially of the control error integral signal IS) is generated, on the basis of which the actual opening voltage values ​​OW1, OW2 can optionally be determined.

[0108] The control device 10 is therefore specifically designed to perform an adjustment of the control opening voltage values ​​RW1, RW2 and / or an identification of the actual opening voltage values ​​OW1, OW2 of the valve characteristics of the piezo valves 6A, 6B on the basis of a vibration analysis, in particular of the control integral signal IS.

[0109] Advantageously, the control device 10 is designed to perform the adjustment and / or identification without direct measurement of a mass flow and / or without model-based disturbance observers and / or without a model-based method, e.g., calculation of a real conductance from a pressure change.

Claims

[1] Method for controlling, in particular pressure controlling, a piezo valve device (30), comprising the steps: - Calculating (S2) a control error integral signal (IS) that represents a time integral of a control error (RF) of the control of the piezo valve device (30), - Adjusting (S4), based on the control error integral signal (IS), at least one control opening voltage value (RW1, RW2), which defines an opening voltage value of a piezo valve (6) of the piezo valve device (30) within the control, and - using the adapted at least one control opening voltage value (RW1, RW2), providing (S5) at least one control voltage (AS1, AS2) for controlling the piezo valve (6) within the framework of the control. [2] Method according to claim 1, wherein the at least one control opening voltage value (RW1, RW2) is adjusted such that the control error integral signal (IS) assumes a predetermined oscillation signal shape, in particular an oscillation signal shape of a preferably symmetrical triangular oscillation. [3] Method according to claim 1 or 2, wherein the at least one control opening voltage value (RW1, RW2) is adjusted such that an actual amplitude (32, 33) of the control error integral signal is equal to a target amplitude. [4] Method according to a preceding claim, wherein the at least one control opening voltage value (RW1, RW2) is adjusted such that it is smaller than an actual opening voltage value (OW1, OW2) of the respective piezo valve (6). [5] Method according to a preceding claim, wherein the calculation (S3) of the control error integral signal (IS) and / or the adjustment (S4) of the at least one control opening voltage value (RW1, RW2) is carried out during the control, in particular the pressure control, of the piezo valve device (30). [6] Method according to a preceding claim, further comprising checking (S3) whether a safety criterion for carrying out the adjustment (S4) is met, wherein the adjustment (S4) is carried out in response to the fact that the safety criterion is met. [7] Method according to a preceding claim, wherein the control comprises a PI control or a PID control, and the control error integral signal is an I-component of the PI control or the PID control. [8] Method according to a preceding claim, wherein the adjustment comprises adjusting a first control opening voltage value (RW1) of a first piezo valve (6A) of the piezo valve assembly (30) and adjusting a second control opening voltage value (RW2) of a second piezo valve (6B) of the piezo valve assembly (30), and wherein the provision of the control voltage comprises providing, using the first control opening voltage value (RW1), a first control voltage (AS1) for controlling the first piezo valve (6A) within the framework of the control and providing, using the second control opening voltage value (RW2), a second control voltage (AS2) for controlling the second piezo valve (6B) within the framework of the control. [9] Method according to claim 8, wherein, within the framework of the control, a pressure fluid supply into a pressure chamber (1) is carried out with the first piezo valve (6A) and a pressure fluid discharge from the pressure chamber (1) is carried out with the second piezo valve (6B). [10] Method according to claim 8 or 9, wherein the adjustment of the first control opening voltage value (RW1) is carried out first, while the second control opening voltage value (RW2) is not adjusted, and only after the adjustment of the first control opening voltage value (RW1) is the adjustment of the second control opening voltage value (RW2) carried out. [11] Method according to claim 10, wherein after adjusting the first control opening voltage value (RW1) the second control opening voltage value (RW2) is adjusted together with a further adjustment of the first control opening voltage value (RW1). [12] Method according to one of claims 8 to 11, wherein the first control opening voltage value (RW1) is adjusted on the basis of a positive actual amplitude (32) of the control error integral signal (IS) and wherein the second control opening voltage value (RW2) is adjusted on the basis of a negative amplitude (33) of the control error integral signal (IS). [13] Method according to a preceding claim, wherein the piezo valve (6) is part of a bridge circuit of the piezo valve device (30). [14] Control device (20) for controlling, in particular pressure controlling, a piezo valve device (30), wherein the control device (20) is configured to calculate a control error integral signal (IS) that represents a time integral of a control error (RF) of the control of the piezo valve device (30), to adapt at least one control opening voltage value (RW1, RW2) on the basis of the control error integral signal (IS), which defines an opening voltage value of a piezo valve (6) of the piezo valve device (30) within the control, and to provide at least one control voltage (AS1, AS2) for controlling the piezo valve (6) within the control using the adapted at least one control opening voltage value (RW1, RW2). [15] Fluidic system (10) comprising a control device (20) according to claim 14 and the piezo valve device (30).

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