Computer-implemented method for optimising pneumatic actuators

Abstract

The invention relates to computer-implemented methods for determining a minimum aeration or deaeration duration of a cylinder chamber of a pneumatic actuator and for determining a minimum travel time of an actuator element, wherein a directional control valve is repeatedly actuated to aerate or deaerate the cylinder chamber until it is detected that an actuator element has reached an end position, wherein either the aeration or deaeration duration required for this purpose or the travel time is then detected. Subsequently, the aeration or deaeration duration is increased or reduced, and it is detected whether the actuator element has reached an end position or what travel time is required for this purpose. The minimum aeration or deaeration duration is ascertained when the actuator element no longer reaches the end position. The minimum travel time is established when a reduction in the travel time is no longer achieved. The invention also relates to a computer program product.

Description

[0001] Computer-implemented methods for the optimization of pneumatic actuators

[0002] The invention relates to methods for optimizing the control of pneumatic actuators, as well as a computer program product.

[0003] DE 10 2022 111 781 A1 describes a pneumatic actuator system. An actuator can be any component or group of components that converts electrical signals and / or current into mechanical movement. Actuators can therefore be used as drive elements. Depending on the application, different actuator systems can be used. For certain cases, electromechanical actuators are too slow or too weak.

[0004] Alternatives include pneumatic actuators, which can reach very high speeds, and hydraulic actuators, which can apply very large forces.

[0005] The present invention deals with the optimization of pneumatic actuators using expansion energy.

[0006] Often, several pneumatic valves are combined in one location, for example, on a carrier plate. This is referred to as a valve island. One advantage of a valve island is the shared or at least centralized air supply to the valves. All valves on the valve island are thus supplied through a common connection, eliminating the need for additional hose lines and connections.

[0007] The object of the present invention is therefore to improve the state of the art.

[0008] The object of the invention is achieved by the subject matter of the independent claims. Advantageous further developments are found in the dependent claims.

[0009] This object is achieved in a first embodiment, in particular, by a computer-implemented method for determining a minimum venting or de-aeration duration of a cylinder chamber of a pneumatic actuator. The method comprises controlling a directional valve for venting or de-aerating the cylinder chamber until an end position of an actuator element is detected. Such an actuator element can, in particular, be a piston. The actuator element spatially delimits the cylinder chamber. The method further comprises detecting a first venting or de-aeration duration required for this purpose. Based on this first venting or de-aeration duration, the following is repeated in a loop-like process:

[0010] The ventilation or venting duration is gradually reduced. In subsequent cycles of the loop, the reduction is carried out based on the ventilation or venting duration of the previous cycle. The directional valve for venting or venting the cylinder chamber is then controlled for the duration of the reduced ventilation or venting duration. It is detected whether the actuator element reaches an end position.

[0011] If it is detected in a cycle that the actuator element does not reach the end position, the process is terminated and the ventilation or de-ventilation time of the previous cycle in which the end position was reached is determined as the minimum ventilation or de-ventilation time.

[0012] The inventive method allows the duration of aeration or venting to be reduced compared to conventional aeration or venting methods, as the expansion energy of the aeration or venting gas can be utilized. This allows energy to be saved.

[0013] According to an advantageous development, the detection of the first ventilation or venting duration can comprise determining a reaction time and a travel time of the actuator element, and the reduction of the ventilation or venting duration can take the reaction time and the travel time into account.

[0014] This is particularly advantageous because it allows the switching times of the actuator to be further optimized, which saves further energy.

[0015] According to a second embodiment, the object is achieved by a computer-implemented method for determining a minimum travel time of an actuator element during operation of the actuator element. The actuator element can in particular be a piston. The actuator element spatially delimits a cylinder chamber of a pneumatic actuator. The method comprises controlling a directional valve for venting or venting the cylinder chamber for a first venting or venting duration until it is detected that an end position of the actuator element has been reached. The method further comprises detecting the first travel time required for this. Starting from this first venting or venting duration, the following is repeated in a loop-like processing: The venting or venting duration is modified step by step. In the subsequent cycles of the loop, the modification is carried out starting from the venting or venting duration of the previous cycle.The directional control valve is then activated to pressurize or vent the cylinder chamber for the duration of the modified pressurization or venting period. The travel time until the end position is reached is recorded by the actuator element.

[0016] In this case, the modification is a shortening or reduction of the ventilation or venting time if the recorded travel time is shorter than the previous travel time, ie the travel time recorded in the previous cycle.

[0017] In this case, modification involves extending the aeration or venting duration if the recorded travel time is longer than the previous travel time, i.e., the travel time recorded in the previous cycle. As soon as a shorter travel time can no longer be recorded, the shortest travel time recorded so far is determined as the minimum travel time.

[0018] Advantageously, the aeration or venting duration is controlled so that the travel time is minimal, thus constantly determining an updated value for the optimal aeration or venting duration. Since the process can be performed during operation, no interruption of operation is required to perform the optimization. The loop-like process can also be continued after the minimum travel time has been determined.

[0019] According to an advantageous further development, the second embodiment comprises determining the aeration or venting duration that leads to achieving the minimum travel time as the optimal aeration or venting duration.

[0020] This is advantageous because it allows operations to be further optimized.

[0021] According to an advantageous further development of all embodiments, the detection of reaching the end position of the actuator element is effected by a limit switch or by evaluation of acoustic information.

[0022] An advantage over known solutions is that no pressure sensors are required. According to an advantageous refinement of all embodiments, the minimum pressurization or depressurization duration or travel time is determined for each cylinder chamber of the pneumatic actuator.

[0023] This also allows actuators with multiple cylinder chambers to be optimized.

[0024] According to an advantageous further development of all embodiments, the directional control valve is a 5 / 4-way valve or a system of two directional control valves with three valve positions each, for example two 4 / 3-, 5 / 3- or 3 / 3-way valves.

[0025] According to an advantageous development of all embodiments, the method further comprises recording the recorded ventilation or venting times or travel times and the respective reaching of the end positions in a machine learning system, wherein the reduction or modification of the ventilation or venting time is carried out by the machine learning system.

[0026] Using a machine learning system, optimization can not only be performed more efficiently and quickly, but also delivers better results.

[0027] According to an advantageous development of all embodiments, the method with a determination of a minimum or optimal aeration or venting duration further comprises setting the determined minimum or optimal aeration or venting duration in a memory of the directional control valve(s), and controlling the directional control valve(s) by a programmable logic controller (PLC) using the defined minimum or optimal aeration or venting duration.

[0028] By configuring the directional control valve in this way, the use of the directional control valve becomes simpler and safer, since the optimized values ​​stored in the directional control valve are transparent to the outside, and the directional control valve can be controlled with simpler signals, since the specific ventilation or venting times do not have to be known by an operator or a control device.

[0029] The advantageous further training courses will also be explained later in the description.

[0030] The embodiments and further developments show possible variants. The invention is not limited to the specifically illustrated variants; rather, combinations of the individual variants are also possible. In particular, the features of the system can also be implemented in a method, and vice versa.

[0031] For a better understanding of the invention, it is explained in more detail with reference to the following figures. They show, in highly simplified, schematic representations:

[0032] Fig. 1 is a graph relating to the first embodiment, and Fig. 2 is a graph relating to the second embodiment.

[0033] By way of introduction, it should be noted that in the variously described embodiments, identical parts are provided with identical reference symbols or component designations. The disclosures contained throughout the description can be applied analogously to identical parts with identical reference symbols or component designations. Furthermore, the positional information chosen in the description, such as top, bottom, side, etc., refers to the directly described and illustrated figure, and these positional information must be applied analogously to the new position in the event of a change in position.

[0034] According to the first embodiment, the pneumatic movement of an actuator can be energy-optimized. Tests with an actuator optimized using this embodiment have demonstrated energy savings of up to 50% compared to other actuators. In most applications, it is generally not necessary to move a cylinder to its end position at full pressure. By intelligently shutting off before reaching the end position and enabling the cylinder to move the remaining distance using the expansion energy of the pneumatic pressure medium used for ventilation or venting, e.g., air, the cylinder can be moved to its end position in an energy-optimized manner.

[0035] With intelligent shutoff, i.e., the use of a reduced pressurization or depressurization duration, only enough air is fed into the pneumatic cylinder to just barely reach the end position. By providing a buffer, reaching the end position can also be ensured. Energy can be saved by shutting off the compressed air supply earlier.

[0036] The advantages here are that intelligent shutdown is a process that requires no modifications to the actuators or cylinders. Furthermore, unlike other state-of-the-art optimization processes, no additional sensors, such as pressure sensors, are required in the valve terminal. The processes can be executed, for example, in or by an industrial controller, also known as a programmable logic controller (PLC). The processes can also be executed by a remote computer over a network or on a mobile device, for example as an app or other application. This means that the optimization processes can basically be used for any valve, meaning that manufacturer-specific parameters do not have to be taken into account.

[0037] If the directional control valve is a 5 / 4-way valve, the actuator's ventilation channel can be switched off in a time-controlled manner via a software module in the control system.

[0038] In principle, a 5 / 4-way valve can also be replaced by two way valves with three valve positions each, for example by two 4 / 3, 5 / 3 or 3 / 3-way valves.

[0039] The reduced filling or deaeration time for the respective cylinder chamber can be determined based on measured reaction and travel times of the cylinder movement under conventional control, i.e., without utilizing the expansion energy during continuous aeration of a cylinder chamber. These determined times are determined via a function block within the PLC from the signal edges for switching the valve and the detection of reaching the two end positions, for example, via end-position sensors, limit switches, or acoustic signals on the cylinder. The corresponding signal curves are shown in Fig. 1.

[0040] Using an iterative process, the ventilation times are gradually reduced during a teach-in process until the cylinder no longer reaches the end positions. This allows the minimum ventilation time to be determined. The interval of possible ventilation times is restricted to the minimum for the user to ensure the movement is executed in any case. The user can then set the desired ventilation time in the function block. This can be done, for example, as a percentage of the ventilation time under normal control.

[0041] The control of the directional control valve's valve coils, i.e., the timely deactivation of the respective solenoid, is also integrated into the function block, allowing the user to treat the directional control valve like a conventional valve. In other words, the user can leave the signal for controlling the solenoid unchanged in their PLC program, e.g., permanently, until the cylinder is to be moved in the other direction. This signal serves as the input signal, while the output provides the signal modified by the process, which is deactivated appropriately for the corresponding directional control valve.

[0042] This allows for a simple teach-in process without the need to enter cylinder parameters, such as those from the manufacturer. The user can perform the teach-in or teach-in process simply by executing a few cycles of cylinder movement.

[0043] Specifically, in the first embodiment, a directional control valve is controlled to vent or vent the cylinder chamber until the actuator element reaches its end position. Such an actuator element can, in particular, be a piston. The actuator element spatially delimits the cylinder chamber. The first venting or venting time is recorded, indicating the length of the required venting or venting time.

[0044] Starting from this first aeration or deaeration period, the following is repeated in a loop-like process:

[0045] In the first cycle, the initial pressurization or venting duration is reduced by a specified increment. The directional valve is then activated for the duration of the reduced pressurization or venting duration. It is detected whether the actuator element reaches an end position. If the actuator element reaches an end position, the next cycle begins, in which the previous pressurization or venting duration is reduced by the specified increment. The directional valve is then activated again.

[0046] If it is detected in a cycle that the actuator element no longer reaches the end position, the process is terminated and the ventilation or de-ventilation time of the previous cycle in which the end position was reached is determined as the minimum ventilation or de-ventilation time.

[0047] When recording the respective aeration or venting times, the reaction time (i.e., how long aeration or venting must take place before the actuator element begins to move) and the travel time (i.e., how long the actuator element moves to the end position) can be recorded additionally or separately. These times can be taken into account when reducing the aeration or venting times. For example, a long travel time can be compensated for with a higher pressure.

[0048] In the second embodiment, the learning process can be carried out during operation, and moreover, the second embodiment can also react to changes in the drive system after the learning process, e.g. ambient temperature, changes in friction parameters due to wear or changes in load, without the operation having to be interrupted for a new learning process.

[0049] In this case, the ventilation or venting duration is not reduced to such an extent that the end position is no longer actually reached, at least during a switching operation. This would lead to a malfunction in the actual operation of a machine. The teach-in process according to the first embodiment is preferably used when a specific operation of the machine can be performed for teach-in purposes.

[0050] In the second embodiment, a minimum travel time is sought initially and then continuously during operation. The travel time is the time the actuator needs to move from one end position to the other. This minimum travel time occurs at an optimal ventilation or venting time. Even if the ventilation or venting time is slightly shorter than the optimal ventilation or venting time, the end position is still reached, so that it is not a problem in the iteration process if the ventilation or venting time is slightly below the optimal ventilation or venting time. If the ventilation or venting time is longer than the optimal ventilation or venting time, the end position is definitely reached, but in this case the compressed air consumption is unnecessarily high.

[0051] Specifically, in the second embodiment, a directional control valve is also activated to vent or vent the cylinder chamber until the end position of an actuator element is detected. However, this can be done during regular operation. Such an actuator element can, in particular, be a piston. The actuator element spatially delimits the cylinder chamber. The travel time required for this is recorded as the first travel time.

[0052] Starting from this first travel time, the following is repeated in a loop-like processing:

[0053] In the first cycle, the ventilation or venting duration is modified by a specified increment. For example, the ventilation or venting duration of the previous operation can be used for this purpose. The directional valve for venting or venting the cylinder chamber is then controlled for the duration of the modified ventilation or venting duration. The travel time until the actuator element reaches an end position is recorded. The next cycle then begins, in which the previous ventilation or venting duration is modified by the specified increment.

[0054] In this case, the modification is a shortening of the ventilation or venting time if the recorded travel time is shorter than the previous travel time, ie the travel time recorded in the previous cycle.

[0055] In this case, modification involves extending the aeration or venting duration if the recorded travel time is longer than the previous travel time, i.e., the travel time recorded in the previous cycle. As soon as a shorter travel time can no longer be recorded, the shortest travel time recorded so far is determined as the minimum travel time.

[0056] The directional control valve is then repeated. The second embodiment can continue to operate continuously, continuously searching for the minimum travel time.

[0057] According to the invention, the pressurization or depressurization duration is controlled so that the travel time is minimal. This constantly determines an updated value for the optimal pressurization or depressurization duration. In fact, the travel time is not shortest when the pressurization or depressurization duration is maximally long, i.e., when the cylinder is pressurized with compressed air at "full force" until the end position is reached. Surprisingly, it is possible to reach the end position more quickly if the cylinder is only pressurized or depressurized briefly, thus utilizing the expansion energy of the compressed air. This allows for speed optimization, i.e., optimization for the shortest travel time.

[0058] Based on the optimal venting or de-venting time with the shortest travel time, the piston needs longer to reach the end position if the venting or de-venting time is shorter.

[0059] In the worst case, it may not reach the final position at all.

[0060] On the other hand, however, the piston also takes longer to reach its end position if the venting or de-venting process is prolonged, as the expansion energy cannot fully develop, meaning the pressure in the cylinder chambers is higher than in the optimized case. Thus, the piston has to do more work to empty the opposing chamber, resulting in a longer travel time.

[0061] Thus, there is a minimum travel time, which is found by the inventive solution. Furthermore, the value of the minimum travel time can be observed over time, since changes in this value can also provide information about wear and / or damage.

[0062] Within the scope of the second embodiment, the ventilation or venting time that leads to the achievement of the minimum travel time can also be determined as the optimal ventilation or venting time.

[0063] In both designs, the pressure in the cylinder chambers is reduced when the piston is in its end positions. This makes it possible to utilize reserves even after optimization to compensate for unforeseen force changes. This can be achieved by changing the ventilation time, as this allows the final pressure in the chambers to be increased again.

[0064] Furthermore, after optimization, a warning can be issued if the ventilation or venting time or travel time changes during operation compared to the optimum found.

[0065] In both embodiments, the detection of the actuator element reaching its end position can be achieved by a limit switch or by evaluating acoustic information. In particular, the acoustic evaluation method eliminates the need for additional components. Reaching the end position is clearly perceptible acoustically, making the corresponding evaluation easy to implement.

[0066] If the actuator has multiple cylinder chambers, the minimum pressurization or depressurization duration or travel time can be determined individually for each cylinder chamber of the pneumatic actuator. This can be particularly advantageous when the cylinder chambers are different and can increase efficiency. The cylinder chambers may also differ only in terms of wear due to different usage.

[0067] The directional control valve can take on any configuration in all embodiments, but use with a 5 / 4-way valve is preferred. If necessary, the 5 / 4-way valve can also be replaced by a system of two directional control valves, each with three valve positions, for example, two 4 / 3-way, 5 / 3-way, or even 3 / 3-way valves. The use of a machine learning system is also particularly advantageous. This system can monitor the recorded ventilation or de-aeration times or travel times and the respective reaching of the end positions and evaluate them based on trained ideal values, thus reducing or modifying the ventilation or de-aeration times more efficiently.

[0068] If a minimum or optimal aeration or venting duration is determined in the method according to the invention, this can also be stored in a memory of the directional control valve, as described above. The directional control valve can then be controlled by a programmable logic controller using the specified minimum or optimal aeration or venting duration.

[0069] A further embodiment is a computer program product comprising instructions which, when executed by a computer, cause the computer to perform one of the methods set out above.

[0070] Another embodiment is a computer-readable medium on which the computer program product is stored.

[0071] The embodiments show possible embodiments, whereby it should be noted at this point that the invention is not limited to the specifically illustrated embodiments thereof, but rather various combinations of the individual embodiments with one another are also possible.

[0072] The scope of protection is determined by the claims. However, the description and drawings must be used to interpret the claims. Individual features or combinations of features from the various embodiments shown and described may represent independent inventive solutions. The problem underlying these independent inventive solutions can be derived from the description.

[0073] All information on value ranges in this description is to be understood as including any and all sub-ranges thereof, e.g. the information 1 to 10 is to be understood as including all sub-ranges, starting from the lower limit of 1 and the upper limit of 10, ie all sub-ranges begin with a lower limit of 1 or greater and end with an upper limit of 10 or less, e.g. 1 to 1.7, or 3.2 to 8.1, or 5.5 to 10. For the sake of clarity, it should be pointed out that in order to improve understanding of the structure, some elements have been shown out of scale and / or enlarged and / or reduced.

Claims

Patent claims 1 . Computer-implemented method for determining a minimum ventilation or venting time of a cylinder chamber of a pneumatic actuator, comprising Controlling a directional control valve for venting or de-aerating the cylinder chamber until it is detected that an end position of an actuator element, in particular a piston that spatially delimits the cylinder chamber, is reached, and detecting a first venting or de-aerating duration required for this; repeatedly reducing the venting or de-aerating duration in steps, starting from the first or previous venting or de-aerating duration; controlling the directional control valve for venting or de-aerating the cylinder chamber for the reduced venting or de-aerating duration; and detecting whether the actuator element reaches an end position; until it is detected that the actuator element does not reach the end position, and then determining the venting or de-aerating duration before the previous reduction in the venting or de-aerating duration as the minimum venting or de-aerating duration.

2. The method according to claim 1, wherein detecting the first ventilation or venting duration comprises determining a reaction time and a travel time of the actuator element, and reducing the ventilation or venting duration takes the reaction time and the travel time into account.

3. Computer-implemented method for determining a minimum travel time of an actuator element, in particular a piston that spatially delimits a cylinder chamber of a pneumatic actuator, during operation of the actuator element, comprising Controlling a directional control valve for venting or de-venting the cylinder chamber for a first venting or de-venting period until the actuator element reaches its end position, and recording the first travel time required for this; repeatedly performing the following steps: gradually modifying the venting or de-venting period, starting from the first or previous venting or de-venting period; Controlling the directional control valve to vent or vent the cylinder chamber for the modified vent or vent duration; and Recording the travel time until the actuator element reaches the end position; if the recorded travel time is shorter than the previously recorded travel time, the modification is a shortening of the ventilation or venting time; and Wherein, if the recorded travel time is longer than the previously recorded travel time, the modification is an extension of the ventilation or venting time; and as soon as no shorter travel time can be recorded, determining the previously shortest travel time as the minimum travel time.

4. The method according to claim 3, further comprising determining the aeration or venting time that results in the minimum travel time being achieved as the optimal aeration or venting time.

5. Method according to one of claims 1 to 4, wherein the detection of reaching the end position of the actuator element is effected by a limit switch or by evaluation of acoustic information.

6. Method according to one of claims 1 to 5, wherein the determination of the minimum ventilation or venting time or travel time is carried out for each cylinder chamber of the pneumatic actuator.

7. Method according to one of claims 1 to 6, wherein the directional control valve is a 5 / 4-way valve or a system of two directional control valves each with three valve positions, for example two 4 / 3-, 5 / 3- or 3 / 3-way valves.

8. The method according to any one of claims 1 to 7, further comprising Recording the recorded ventilation or venting times or travel times and the respective reaching of the end positions in a machine learning system, whereby the reduction or modification of the ventilation or venting time is carried out by the machine learning system.

9. The method according to any one of claims 1, 2 or 4 to 8, further comprising Setting the specific minimum or optimal ventilation or venting time in a memory of the directional control valve, and Control of the directional control valve by a programmable logic controller, using the specified minimum or optimal ventilation or venting time.

10. A computer program product comprising instructions which, when executed by a computer, cause the computer to carry out the steps of the method according to any one of claims 1 to 9.

11. A computer-readable data carrier on which the computer program product according to claim 10 is stored.

12. A data carrier signal transmitting the computer program product according to claim 10.

Images