METHOD FOR OPERATING A HYDRAULIC CYLINDER OF A WORK MACHINE

Description

State of the art

[0001] The invention relates to a method and a control unit for operating a hydraulic cylinder, as well as a method and a control unit for operating a working unit of a, in particular mobile, working machine that can be operated by means of a hydraulic cylinder. The present invention also relates to a working machine, a computer program, and a computer-readable data carrier.

[0002] Modern construction machinery increasingly enables automated or semi-automated work processes. This functionality often involves the automated following of a desired trajectory for the Tool Center Point (TCP), or, in the case of assistance functions, supporting the driver in following a desired trajectory. Data-based rule structures are used for this purpose.

[0003] Since the pressure differential across an orifice of a valve unit associated with the hydraulic cylinder is highly dependent on the load acting on the working unit, the data generation effort required to fully cover the possible operating range of the working unit with a purely data-based model is very high. In particular, generating training data under different loads may be necessary. US 2020 / 0123927 A1 discloses a method for controlling a gas turbine engine system using adaptive model-based control.

[0004] US 2020 / 0097851 A1 discloses a method for processing digital agricultural data using a machine learning model to control an agricultural machine. Disclosure of the invention

[0005] According to a first aspect, the present invention relates to a method for operating a hydraulic cylinder of a, in particular mobile, working machine.

[0006] The process includes a step of receiving a setpoint value of a movement parameter of the hydraulic cylinder by means of a control unit.

[0007] The procedure further includes a step of determining a setpoint for a valve control parameter of a valve unit assigned to the hydraulic cylinder, depending on the received setpoint of the motion parameter via the control unit. Here, the setpoint of the valve control parameter is determined using a physical model and a data-based model, in particular an artificial neural network.

[0008] The method further includes a step of outputting a signal, depending on the determined setpoint of the valve control parameter, by means of the control unit, in particular indirectly or directly to the valve unit, in order to operate the hydraulic cylinder.

[0009] According to a second aspect, the present invention relates to a method for operating a working unit, in particular an attachment, or a, in particular mobile, working machine, which can be operated by means of a hydraulic cylinder.

[0010] The method comprises a step of receiving a target position of the working unit, in particular the attachment, by means of a control unit. The method further comprises a step of determining a target value of a movement parameter of the hydraulic cylinder as a function of the received target position of the working unit by means of the control unit.

[0011] The procedure also includes a step of determining a setpoint of a valve control parameter of a valve unit assigned to the hydraulic cylinder as a function of the received setpoint of the motion parameter using a physical model and a data-based model by means of the control unit.

[0012] The method further comprises a step of outputting a signal depending on the determined setpoint of the valve control parameter by means of the control unit, in particular indirectly or directly to the valve unit, in order to operate the working unit, in particular the attachment, of the, in particular mobile, working machine by operating the hydraulic cylinder.

[0013] According to a third aspect, the invention relates to a control unit for operating a hydraulic cylinder of a, in particular mobile, working machine. The control unit is configured to receive a setpoint of a motion parameter of the hydraulic cylinder. Furthermore, the control unit is configured to determine a setpoint of a valve control parameter of a valve unit associated with the hydraulic cylinder, based on the received setpoint of the motion parameter, using a physical model and a data-based model. Finally, the control unit is configured to output a signal, based on the determined setpoint of the valve control parameter, in particular directly or indirectly to the valve unit, in order to operate the hydraulic cylinder.

[0014] According to a fourth aspect, the invention relates to a control unit for operating a working unit, in particular an attachment, a working machine, especially a mobile one, which can be operated by means of a hydraulic cylinder.

[0015] The control unit is configured to receive a target position of the working unit, in particular the attachment. The control unit is also configured to determine a target value of a movement parameter of the hydraulic cylinder based on the received target position of the working unit. Furthermore, the control unit is configured to determine a target value of a valve control parameter of a valve unit associated with the hydraulic cylinder based on the received target value of the movement parameter, using a physical model and a data-based model. Finally, the control unit is configured to output a signal based on the determined target value of the valve control parameter in order to operate the working unit, in particular the attachment, of the (especially mobile) working machine by operating the hydraulic cylinder.

[0016] According to a fifth aspect, the invention relates to a, in particular mobile, working machine, comprising a working unit, in particular an attachment, at least one hydraulic cylinder for moving the working unit, in particular the attachment, and a control unit described above for operating the working unit, in particular the attachment.

[0017] According to a further aspect, the invention relates to a computer program or a computer program product comprising instructions which, when executed by a computer or a control unit, cause it or these to execute and / or control the method according to the first aspect of the invention and / or the method according to the second aspect of the invention, as well as a computer-readable data carrier on which the computer program is stored. The computer-readable or machine-readable data carrier can be, for example, a storage medium such as semiconductor memory, hard disk storage, or optical storage.

[0018] The machine used can be stationary or, preferably, mobile. It can be used for construction, agriculture, forestry, or logistics purposes. Examples of mobile machines include excavators, wheel loaders, bulldozers, forklifts, and aerial work platforms. Stationary machines can include hydraulically driven industrial robots.

[0019] The working unit of the machine can be a unit for cultivating and / or treating agricultural, forestry, and / or construction land, and / or for transporting a load. The working unit can be an attachment. It is also conceivable that the working tool includes a working arm, a lifting frame, or a lifting mast.

[0020] The attachment could be, for example, a spoon, a shovel, or a work basket.

[0021] The attachment can be arranged on a working arm, a lifting frame or a lifting mast of the machine.

[0022] The hydraulic cylinder is designed to generate relative motion between the working unit or attachment and the main machine unit of the machine. The main machine unit comprises, for example, an operator's cab and / or a drive unit for the working unit. The main machine unit can be, for example, the upper structure of an excavator or the rear structure of a wheel loader. The working unit or attachment is thus movable relative to the main machine unit of the machine by means of the hydraulic cylinder. For this purpose, the hydraulic cylinder comprises a housing and a piston. The piston is movable relative to the housing by means of pressurizing it with a hydraulic fluid, preferably a hydraulic fluid; in particular, it can be moved in and out of the housing.

[0023] The valve unit associated with the hydraulic cylinder is designed to regulate a predetermined and / or adjustable flow rate of the hydraulic fluid through the valve unit and / or to apply a predetermined and / or adjustable pressure to the hydraulic fluid. The valve unit associated with the hydraulic cylinder is designed to generate relative movement between the piston and the housing of the hydraulic cylinder.

[0024] The valve unit can comprise one or more valves. The valve can be designed as a solenoid valve or a pneumatically actuated valve. The valve unit can include a pilot valve, in particular an electromagnetic pilot valve, and preferably a main valve associated with the pilot valve, in particular a pneumatically actuated main valve.

[0025] By controlling the valve unit based on the output signal, a relative movement between the piston and the housing of the hydraulic cylinder can be controlled. This relative movement, depending on the arrangement of the hydraulic cylinder on the machine, can generate a relative movement between the attachment and the main machine unit of the machine, in particular between the attachment and a working arm and / or a lifting frame of the machine.

[0026] Within the scope of the present invention, "control" can be understood as control in the sense of generating an output variable based on an input variable. More specifically, and preferably, "control" can be understood as control encompassing regulation in the sense of continuously determining the actual value of a variable to be controlled and continuously comparing the actual value with a setpoint value of the variable to be controlled.

[0027] The control unit preferably comprises one or more controllers, particularly cascaded controllers. The control unit can be located on the machine. Alternatively, the control unit can be located away from the machine, e.g., in a server backend or a cloud computing system, and be connected to the machine via a wireless communication link.

[0028] A target position of the work unit can be a spatial relative position of the work unit relative to the machine encompassing the work unit, or a spatial position in an external reference coordinate system, such as a global satellite navigation system or a reference coordinate system of a position-detecting sensor unit. The target position of an attachment is preferably a spatial position of the attachment's Tool Center Point (TCP). The target position of the work unit or attachment can be specified, for example, for a work step of a work process to be performed by the machine. The target position of the attachment can also include a spatial orientation of the attachment, for example, relative to the main unit of the machine.

[0029] Determining the target value of the motion parameter as a function of the target position of the work unit can be achieved using software-based trajectory planning for the work unit, attachment, or machine. This determination can be performed by considering at least a portion of the machine's kinematics.

[0030] The motion parameter of the hydraulic cylinder is a parameter of the movement of the hydraulic cylinder. The movement of the hydraulic cylinder is preferably a relative movement between the piston and the housing of the hydraulic cylinder. The movement of the hydraulic cylinder can be uniform or, preferably, uniformly accelerated.

[0031] The motion parameter of the hydraulic cylinder can be a velocity and / or an acceleration. Preferably, the motion parameter is a relative velocity or relative acceleration between the piston and the housing of the hydraulic cylinder. The motion parameter can include a magnitude and a direction of the velocity and / or acceleration.

[0032] Within the scope of the present invention, receiving or determining a setpoint can be understood as receiving or determining at least one setpoint. Here, the setpoint is a predetermined and / or predeterminable value and / or a previously determined value. Preferably, receiving or determining the setpoint comprises receiving or determining a plurality or set of setpoints. It is conceivable that the plurality or set of setpoints represents a temporal sequence of setpoints.

[0033] The target value of the movement parameter is accordingly a value or a time course of the value of the movement parameter, according to which a movement of the hydraulic cylinder should take place.

[0034] The valve control parameter of the valve unit can be a parameter of one or more valves within the unit, based on which the valve(s) of the unit are controlled. The valve control parameter can be a valve current or the current intensity of a solenoid valve. It can also be a pressure used to actuate a pneumatically operated valve. Furthermore, the valve control parameter can be a geometric and / or fluidic valve parameter, such as the opening area of ​​a valve orifice within the valve unit. It is also conceivable that the valve control parameter is the position of a control element, particularly a joystick, of the machine. The control element can serve as a means of controlling the movement of the hydraulic cylinder. The position of the machine's control element can be a position or a Z-state of the control element. Depending on the position or state...The state of the control element controls the valve unit associated with the hydraulic cylinder in order to move the hydraulic cylinder. For this purpose, each position of the control element is assigned a control signal for controlling the valve unit, or a corresponding state of the valve unit.

[0035] Advantageously, the setpoint of the valve control parameter is further determined as a function of, in particular, a value of at least one other parameter of the hydraulic cylinder and / or the working machine. This other parameter is preferably different from the motion parameter. The other parameter can also correspond to a time derivative of the motion parameter. The other parameter can be a pressure, for example, the pressure of a hydraulic fluid in the hydraulic cylinder. The other parameter is preferably a pressure difference between a pressure on a piston side of the hydraulic cylinder and a pressure on a rod side of the hydraulic cylinder. Alternatively or additionally, the other parameter is a difference between a load pressure of the working unit and a pressure provided by a pump unit for pressurizing the hydraulic fluid.It is also conceivable that the additional parameter is the temperature of the hydraulic fluid in the hydraulic cylinder. It is further conceivable that the additional parameter is the rotational speed of the motor in the working machine.

[0036] For the purposes of this application, a physical model can be understood as a mathematical model or algorithm designed to map an input quantity to an output quantity using one or more physical equations or functions. The one or more physical equations represent or approximate a physical law underlying the relationship between the input and output quantities. Following the nomenclature of systems theory, the physical model can also be referred to as a white-box model.

[0037] The output signal or value of the physical model can be used to validate the procedure. It is conceivable that the output value is compared to a predefined or definable dynamic or constant threshold, and an error mode is activated depending on the comparison. Furthermore, it is conceivable that a simplified model is used to execute the procedure when the error mode is activated. This can improve the robustness of the procedure.

[0038] Within the scope of the present invention, a data-based model can be understood as a mathematical model or algorithm designed to map an input variable to an output variable using training data. The training data represents a correlation between values ​​of the input variable and values ​​of the output variable. The data-based model is preferably designed as an artificial neural network. Following the nomenclature of systems theory, the data-based model can also be referred to as a black box model. In particular, the data-based component can represent a non-linear part of the model, especially a part of the model that is significantly dependent on a load acting on the work unit.

[0039] The training data can be determined during operation of the hydraulic cylinder, for example, during operation of a machine that incorporates the hydraulic cylinder. The training data corresponds to combinations of values ​​that occur or are present during operation of the hydraulic cylinder.

[0040] A combination, especially a parallel or sequential use, of a data-based model and a physical model can also be referred to as a grey box model or hybrid model, following the nomenclature of systems theory.

[0041] When determining the setpoint of the valve control parameter, the data-based model and the physical model can be used in parallel or sequentially. The physical or data-based model can be part of a feedforward control system for a controller used to determine the setpoint of the valve control parameter. Preferably, both the data-based and the physical models are part of a feedforward control system for a controller used to determine the setpoint of the valve control parameter.

[0042] The purpose of modeling can be very diverse: With the same data and the same model structure, both the forward behavior, which is important for diagnostic functions, and the backward behavior, which is important for controlling the work unit, can be simulated or replicated.

[0043] The control unit is preferably arranged on the, in particular mobile, working machine. It is also conceivable that the control unit is arranged away from the working machine and preferably connected to it via a wireless communication link.

[0044] The methods according to the invention and the corresponding control units increase the safety and reliability of the automated operation of a hydraulic cylinder or a working unit of a, in particular mobile, machine that can be moved by means of the hydraulic cylinder. By using a data-based model, a work process can also be (partially) automated for a machine that exhibits complex hydraulic behavior and can only be fully described by a sufficiently detailed physical model with a particularly high level of effort.

[0045] At the same time, using a physical model reduces the effort required to train the data-driven model, especially for applications with large workspaces or parameter spaces. In particular, the robustness of the method can be increased in less frequently occurring workspaces or workspaces for which less training data is available.

[0046] It is advantageous if, in the step of determining the target value of the valve control parameter, An output value of the physical model is determined as a function of the setpoint of the motion parameter, and the setpoint of the valve control parameter is determined as a function of the output value using the data-based model. In other words, an output value determined using the physical model as a function of the setpoint of the motion parameter is provided as an input value for the data-based model to determine the setpoint of the valve control parameter. Preferably, the setpoint of the motion parameter is the input value for the physical model. This design allows the setpoint of the motion parameter to be deterministically transformed into another physical quantity, even when considering other influencing factors. This second physical quantity is then mapped to the setpoint of the valve control parameter using the data-based model.

[0047] It is also advantageous if the output of the physical model is a setpoint for a valve parameter of the valve unit, in particular for a valve opening size or for a volume flow rate assigned to the valve unit. The valve parameter can be a geometric and / or fluidic parameter of a valve within the valve unit. For example, the physical model can include an orifice equation for a pressure-dependent volume flow rate of hydraulic fluid through an orifice of a valve within the valve unit. This design allows the use of physical laws that can be implemented with minimal computing resources, thus reducing the training effort for the data-driven model.

[0048] It is also advantageous if, in the step of determining the target value of the valve control parameter, An output value of the data-driven model is determined based on the setpoint of the motion parameter, and the setpoint of the valve control parameter is determined based on the output value obtained using the physical model. It is advantageous if the output value of the data-driven model is a setpoint for a valve opening size or for a volume flow rate associated with the valve unit. In other words, an output value determined using the data-driven model based on the setpoint of the motion parameter is provided as an input value for the physical model to determine the setpoint of the valve control parameter. Preferably, the setpoint of the motion parameter is the input value for the data-driven model.This design allows the target value of the motion parameter to be converted into another physical quantity, which, using the physical model, is deterministically mapped to the target value of the valve control parameter, even when considering other influencing factors.

[0049] Furthermore, it is advantageous if, in the step of determining the target value of the valve control parameter, Using the physical model, a first value for an output variable is determined; using the data-based model, a second value for the same output variable is determined; and the setpoint of the valve control parameter is determined based on a comparison of the first and second values. The output variable is preferably the setpoint of the valve control parameter. The second value can be limited by a predefined and / or predefinable range of values. In particular, the second value can be set to a boundary value of the range if it lies outside the range. Furthermore, the data-based model can be used without inputting or applying pressures or pressure differences, essentially correcting errors in the stationary cylinder model. This design allows for plausibility verification of the results obtained using a white-box model or similar method.The output value determined by a black box model can be used, allowing the setpoint of the valve control parameter to be determined with higher reliability.

[0050] It is also advantageous if, in the step of determining the target value of the valve control parameter, Using the physical model and the data-based model, a first value for an output variable is determined, a second value for the same output variable is determined using a further data-based model, and the setpoint of the valve control parameter is determined based on a comparison of the first and second values. The output variable is preferably the setpoint of the valve control parameter. This design allows for plausibility checks of the output variable determined using a grey-box model, thereby enabling a more reliable determination of the valve control parameter setpoint.

[0051] It is particularly advantageous if The machine comprises at least one additional hydraulic cylinder; in the receiving step, a further setpoint for a further motion parameter of the additional hydraulic cylinder is received by the control unit; in the determining step, a further setpoint of a further valve control parameter of a further valve unit assigned to the additional hydraulic cylinder is determined as a function of the received further setpoint using a further physical model and a further data-based model by the control unit; using the physical model and the data-based model, a first value for an output variable for the hydraulic cylinder is determined; using the further physical model and the further data-based model, a further first value for a further output variable for the additional hydraulic cylinder is determined.Using an additional data-based model, a second value is determined for the output size of the hydraulic cylinder and the further output size of the other hydraulic cylinder, and the respective setpoint of the valve control parameters is determined based on a comparison of the first and second values, and in the output step, the signal is output depending on the determined setpoints of the valve control parameters to operate the hydraulic cylinders.

[0052] This design allows for the consideration of interactions or correlations between at least two hydraulic cylinders using a single additional data-based model, thus increasing the quality of the method.

[0053] Furthermore, it is advantageous if the setpoint of the valve control parameter is determined using a speed controller, where the speed controller includes feedforward control based on the physical model and the data-based model. This design enables the method to provide speed control for a hydraulic cylinder of a machine, characterized by low training requirements and simultaneously high accuracy, even in operating ranges with little or no training. Drawings

[0054] The invention is explained in more detail below with reference to the accompanying drawings. These show: Fig. 1 a schematic representation of a control unit for operating a working unit of a machine; and Fig. 2 a schematic representation of a model-based feedforward control according to a first embodiment; Fig. 3 a schematic representation of a model-based feedforward control according to a second embodiment; Fig. 4 a time-resolved representation of a joystick signal; Fig. 5 a flowchart of a method for operating a hydraulic cylinder of a machine; and Fig. 6 a flowchart of a method for operating a working unit of a machine.

[0055] Figs. 1Figure 1 shows a schematic representation of a control unit 10 for operating a working unit of a, in particular mobile, working machine, which is operated by means of a hydraulic cylinder 26. The working machine comprises the working unit, the hydraulic cylinder 26, a valve unit 24 associated with the hydraulic cylinder 26, and the control unit 10. The working unit is operated by means of the hydraulic cylinder, in particular moved relative to a main machine unit of the working machine.

[0056] The machine being worked could be, for example, an excavator, which includes a working unit designed as a working arm. The working arm has a boom, a stick, and a bucket, as well as a boom cylinder, a stick cylinder, and a bucket cylinder. Each of the cylinders is assigned a corresponding valve unit for moving the cylinder.

[0057] Control unit 10 is set up, a target position is established. x R to receive the work unit. The target position can be determined here. x R Furthermore, it may include information regarding the spatial orientation of the work unit. For example, control unit 10 may be configured to receive the spatial target coordinates of a tool center point (TCP) of the excavator bucket, as well as the angle of the bucket relative to a specified reference direction.

[0058] The target position x R can be part of a target trajectory of the work unit. It is conceivable that the target trajectory is determined by an operator of the working machine and / or by means of a computing unit 12 to generate a target trajectory for the working machine and is provided to the control unit 10.

[0059] The target position is preferred. x RThe work unit is provided with a pose module 14 of the control unit 10. The pose module 14 is preferably designed and configured as part of a cascade controller, which determines the target position. x R the work unit and furthermore the actual position x the work unit from one the actual position x The sensor unit 28, which detects the work unit, is to be received. Furthermore, the pose module 14 is configured based on a deviation from the target position. x R and actual position x a target speed for the work unit Where R to determine the work unit by means of which the actual position x into the target position x R can be transferred. For example, the target position is set using the Posen module 14. x R of the TCP and the actual position x Received the TCP signal and, based on the deviation, a target TCP speed is determined. Where R calculated.

[0060] The control unit 10 includes an inverse kinematics module 16, which is set up based on the target speed. Where R a target value for the work unit A R A movement parameter of the hydraulic cylinder is determined. Determining the target value. A R The determination of the motion parameter is preferably carried out taking into account the kinematics of the working unit of the machine, in particular by solving the inverse kinematic problem for the machine. For example, based on the target speed Where R Each of the TCP of the excavator has a target speed. A R calculated for the boom cylinder, the stick cylinder and the bucket cylinder.

[0061] The control unit 10 is also set up to determine a setpoint using a speed module 18. u a valve control parameter of the hydraulic cylinder 26 as a function of the setpoint A R to determine the motion parameter.

[0062] The speed module 18 is preferably designed and configured as a speed controller 18, which sets the setpoint. A R of the movement parameter and the actual value with R to receive the movement parameter of the hydraulic cylinder. Furthermore, the speed module 18 is set up based on a deviation between the setpoint and the actual value. A R and the actual value B the target value of the movement parameter u to determine the valve control parameter.

[0063] Preferably, the speed module 18 is set up, in addition to one or more of the following influencing factors when determining the setpoint. u to take into account the valve control parameter: Actual value s̈ an acceleration of the hydraulic cylinder 26, actual value of a pressure on a cylinder rod of the hydraulic cylinder 26, actual value of a pressure on a cylinder head of the hydraulic cylinder 26, difference Δ p cylbetween the actual pressure at the cylinder rod and the actual pressure at the cylinder head 26, the actual load pressure of the working unit, the actual pump pressure of a pump unit assigned to the hydraulic cylinder 26 for pressurizing a hydraulic fluid moving the hydraulic cylinder 26, difference Δ p sys between the actual value of the load pressure and the actual value of the pump pressure, the actual value of an ambient temperature and / or an engine oil in an oil circuit of the working machine.

[0064] The speed module 18 preferably comprises a PI controller with model-based feedforward control 18a. This allows the PI controller to be relieved of some of the load, even in complex and nonlinear behavior, so that its feedback control 18b only needs to consider disturbances and model errors.

[0065] The model-based feedforward control 18a represents an inverse behavior of the working unit with respect to the relationship between the motion parameter of the hydraulic cylinder 26 and the valve control parameter of the respective valve unit. In other words, the model-based feedforward control 18a determines a value u of the movement parameter of the hydraulic cylinder 26 based on a predefined value A R of the valve control parameter. Here, model-based feedforward control 18a is carried out using a physical model and a data-based model.

[0066] The preferred method for determining the target value is... u of the valve control parameter of the hydraulic cylinder 26 additionally one or more of the above-mentioned influencing factors, preferably, in particular, a combination of, ṡ s̈ , Δ p cyl , Δ p sys taken into account.

[0067] For the excavator with boom cylinder, stick cylinder and bucket cylinder, the control unit 10 includes a speed module 18 designed as a PL controller for determining a setpoint value. u of the valve control parameter for the valve unit assigned to the respective cylinder. Each of the PI controllers includes its own model-based feedforward control 18a.

[0068] The target value u The valve control parameter is output as the manipulated variable of speed module 18. Here, the setpoint is... u of the valve control parameter, in particular a sum of an output variable on FB the return 18a and an output size and FF model-based feedforward control 18b.

[0069] The model-based feedforward control 18a is based on a physical model and a data-based model of the controlled system, as exemplified in Figs. 2 and Figs. 3shown. That is, in other words, the target value to be determined. u The valve control parameter is adjusted based on the received setpoint. A R the velocity parameter of the hydraulic cylinder 26 was determined using the physical model and the data-based model.

[0070] Control unit 10 is further configured to display the determined setpoint. u to output the valve control parameter to system 20. System 20 comprises a control module 22, the valve unit 24, and the hydraulic cylinder 26. System 20 represents a control loop of the speed controller 18.

[0071] The control module 22 is configured to operate the valve unit 24 based on the signal output by the control unit 10. The valve unit 24 is configured to adjust the flow of hydraulic fluid through the valve unit 24 in response to the signal output to the control module 22, in order to move the hydraulic cylinder 26. That is, in other words, by outputting the signal to the valve unit 24 depending on the determined setpoint. u The hydraulic cylinder 26 is operated by the valve control parameter, thus moving the working unit.

[0072] One or more of the sensors 28 arranged on the working machine are designed to determine the actual position x of the work unit, an actual position or actual state s of the hydraulic cylinder 24, and preferably the influencing factors listed above, in particular , ṡ s̈ , Δ p cyl , Δ p systo measure. In this process, preferably suitable model-based filters 30 are assigned to the sensors 28.

[0073] The model-based filters 30 are set up, the actual position x to output the actual position or actual state of the work unit to the pose module 14 and to the inverse kinematics module 16. s output of the hydraulic cylinder 24 to the inverse kinematics module 16, and preferably the influencing factors listed above, in particular , ṡ s̈ , Δ p cyl , Δ p sys to output to the speed module.

[0074] Figs. 2 shows a representation of a first exemplary embodiment of the model-based feedforward control 18a.

[0075] The model-based feedforward control 18a represents an inverse model of the controlled system. This inverse model comprises a physical model 34 and a data-based model 32.

[0076] The physical model 34 is set up, the target value A R a setpoint for the movement parameter of the hydraulic cylinder and FF to assign the valve control parameter. For this purpose, the physical model 34 includes a first module 36, which is set up based on the setpoint. A R a setpoint for the movement parameter, taking into account or neglecting pressure build-up dynamics within the hydraulic cylinder Q vlv,R to determine the volume flow rate of a hydraulic fluid through the valve unit assigned to the hydraulic cylinder. For example, a setpoint can be determined. Q Hd,R a volume flow of the hydraulic fluid at the head of the hydraulic cylinder and a setpoint Q Rd,R The volume flow rate of the hydraulic fluid at the cylinder rod of the hydraulic cylinder can be calculated. The physical model 34 can include a first module 36, which is set up to determine the setpoint. Q vlv,RThe pressure build-up dynamics of the hydraulic cylinder must be taken into account when considering the volume flow rate.

[0077] If the pressure build-up dynamics of the hydraulic cylinder 36 are neglected, a steady-state relationship results between the cylinder velocity. A R and the volume flow Q vlv,R , which depends on the piston area of ​​the hydraulic cylinder 36. In this case, providing cylinder pressures, especially measured ones, is not necessary for the physical model 34.

[0078] The physical model 34 includes a second module 38, which is set up based on the determined setpoint. Q vlv,R a setpoint for the volume flow A vlv,R to determine the opening area of ​​a valve unit's aperture.

[0079] Preferably, the physical model 34 is set up when determining the setpoint. A vlv,R A pressure difference Δ exists across the aperture area of ​​the aperture. p cylbetween the actual pressure at the cylinder rod and the actual pressure at the cylinder head and / or a pressure difference Δ p sys The difference between the actual load pressure and the actual pump pressure must be taken into account. Alternatively, physical model 34 can be configured when determining the setpoint. A vlv,R The opening area of ​​the aperture uses a predetermined and / or predefinable value for the pressure difference Δ instead of a measured one. p cyl and / or pressure difference Δ p sys to take into account, for example, if no pressure sensor is available.

[0080] The physical model 34 further includes a third module 40, which is set up based on the determined setpoint. A vlv,R a first output value from the aperture area of ​​the aperture u FF, 1 to determine the valve control parameter. The third module 40 of the physical model 34 can be set up when determining the first output value. u FF,1. To take into account the valve dynamics of the valve unit for the valve control parameter.

[0081] The data-based model 32 is designed and configured as an artificial neural network 32, according to the setpoint. A R a second output value for the movement parameter of the hydraulic cylinder u FF ,2 to be assigned to the valve control parameter.

[0082] Preferably, the data-based model 32 is set up, in addition to one or more of the following influencing factors when determining the second output value. u FF ,2 to consider for the valve control parameter: Target value s¨ R and / or actual value s̈ acceleration of the hydraulic cylinder, actual pressure value at a cylinder rod of the hydraulic cylinder, actual pressure value at a cylinder head of the hydraulic cylinder, difference Δ p cylbetween the actual pressure at the cylinder rod and the actual pressure at the cylinder head, the actual load pressure of the working unit, the actual pump pressure of a pump unit assigned to the hydraulic cylinder for pressurizing a hydraulic fluid moving the hydraulic cylinder, difference Δ p sys between the actual value of the load pressure and the actual value of the pump pressure, the actual value of the ambient temperature and / or the temperature of the engine oil in an oil circuit of the working machine.

[0083] Based on the first output value determined by the physical model 34 u FF, 1 and the second output value determined by the data-based model 32 u FF ,2 of the valve control parameter is the setpoint by the pilot control 18a and FF The valve control parameter is output. and FFof the valve control parameter as the sum of the first output value determined by the physical model 34 u FF, 1 and the second output value determined by the data-based model 32 u FF ,2 of the valve control parameter is output.

[0084] The data-based model 32 can be trained using a training procedure in which, for example, a root mean square error related to the difference, given in residual form as 0 = u FF - u FF , 1 - u FF , 2 is determined. Here, a value of the first output size is used. u FF, 1 is specified by the physical model 34, while the value of the second output quantity u FF ,2 is optimized via the parameters of the data-based model 32 with regard to minimizing the above Root Mean Square Error.

[0085] The manipulated variable of the speed controller 18, namely the setpoint u of the valve control parameter, is based on the output variable and FF adapted to the model-based feedforward control 18a.

[0086] Figs. 3 shows a representation of a second exemplary embodiment of the model-based feedforward control 18a'.

[0087] The model-based feedforward control 18a' according to Figs. 3 differs from model-based feedforward control 18a according to Figs. 2 through another data-based model 42' and by the fact that the physical model uses the setpoint as its output variable A vlv,R provides the opening area of ​​the valve unit's aperture.

[0088] In other words, the physical model 34' includes a first module 36' which is set up based on the setpoint. A R a setpoint for the movement parameter, taking into account or neglecting pressure build-up dynamics within the hydraulic cylinder Q vlv,Rto determine the volume flow rate of a hydraulic fluid through the valve unit associated with the hydraulic cylinder. The physical model 34' includes a second module 38', which is set up based on the determined setpoint. Q vlv,R a setpoint for the volume flow A vlv,R to determine the opening area of ​​a valve unit's aperture.

[0089] The further data-based Model 42' is set up, based on the determined target value. A vlv,R the target value of the aperture area of ​​the aperture and FF to determine the valve control parameter.

[0090] Based on the first output value determined by the physical model 34' and the further data-based model 42' u FF, 1 and the second output value determined by the data-based model 32' u FF ,2 for the valve control parameter, a setpoint is determined by the pilot control 18a'. and FFThe valve control parameter is output. and FF of the valve control parameter as the sum of the first output value determined by the physical model 34' and the further data-based model 42' u FF, 1 and the second output value determined by the data-based model 32' u FF ,2 of the valve control parameter is output.

[0091] The data-based model 32' and the further data-based model 42' can be trained using a parallel training procedure.

[0092] The manipulated variable of the speed controller 18, namely the setpoint u of the valve control parameter, is based on the output variable and FF adapted to the model-based feedforward control 18a'.

[0093] Figs. 4 shows a time-resolved representation of a real measured joystick signal. u1 of an excavator during a TCP trajectory for the tool center point of the bucket compared with one using a data-based model (32; 32') ( Figs. 4a ) and using a data-based and a physical model ( Figs. 4b ) determined joystick signal u 2 , u 3 when given the actual trajectory traveled.

[0094] Under a joystick signal u A valve control parameter can be used here u be understood, because the joystick signal u represents a position or setting of the joystick, which corresponds to a corresponding control of the valve units of the boom, stick and bucket cylinders of the excavator.

[0095] The data-driven models in Figs. 4a and Figs. 4bThey were trained using the same set of training data. This training data includes TCP speeds and associated joystick positions for different pressure differences between the cylinder rod and cylinder head.

[0096] Furthermore, the training data can include values ​​for one or more of the following quantities: volume flow, aperture area, valve slide position, cylinder position, cylinder pressures, and derivatives of these quantities.

[0097] During the generation of the training data, the excavator was operated with an empty bucket, i.e., without a load. When traversing the TCP trajectory, the bucket was empty during an initial time interval. t 1 unfilled and in a second time interval t 2. Filled. Accordingly, the pressure difference between the actual pressure at the cylinder rod and the actual pressure at the cylinder head differs in the second time interval. t 2 significant from the first time interval t1. Similarly, the pressure difference between the actual value of the load pressure and the actual value of the pump pressure differs in the second time interval. t 2 significant from the first time interval t 1 . This creates significantly more difficult conditions for the use of a data-based model (32; 32').

[0098] In comparison of Figs. 4a and Figs. 4b Advantages of using a data-based model (32; 32') and a physical model in the operation of a hydraulic cylinder are shown, especially under conditions unfavorable to the data-based model.

[0099] Figs. 4a shows in the first time interval t 1. a significantly higher correlation between the real joystick signal u 1 and the joystick signal calculated using a data-based model (32; 32') u 2 as in the second time interval t2, in which the bucket was filled, unlike in the training data.

[0100] Figs. 4b shows in the first time interval t 1. a higher degree of agreement between the real joystick signal u 1 and the joystick signal calculated using a data-based and a physical model u 3 as in the second time interval t 2. However, the deviation in the second time interval t 2 less than the deviation in the second time interval t 2 according to Figs. 4a , because the physical model takes into account the influence of the significantly different pressure difference in the loaded state of the spoon compared to the unloaded state of the spoon.

[0101] The deviation between the real joystick signal u 1 and the joystick signal calculated using a data-based and a physical model u 3 in the first time intervalt 1 is comparable to the deviation in the first time interval t 1 according to Figs. 4a .

[0102] Figs. 5 Figure 1 shows a flowchart of a method for operating a hydraulic cylinder of a, in particular mobile, working machine. The method as a whole is designated by reference numeral 100.

[0103] In step 110, a target value of a movement parameter of the hydraulic cylinder is received by means of a control unit.

[0104] In step 120, a setpoint of a valve control parameter of a valve unit assigned to the hydraulic cylinder is determined as a function of the received setpoint of the motion parameter using a physical model and a data-based model (32; 32') by means of the control unit.

[0105] In step 130, a signal is output by the control unit depending on the determined setpoint of the valve control parameter in order to operate the hydraulic cylinder.

[0106] Figs. 6 Figure 1 shows a flowchart of a method for operating a working unit, in particular an attachment, of a (particularly mobile) working machine, which can be operated by means of a hydraulic cylinder. The method as a whole is designated by reference numeral 200.

[0107] In step 210, a target position of the work unit, in particular the attachment, is received by means of a control unit.

[0108] In step 220, a target value of a movement parameter of the hydraulic cylinder is determined as a function of the received target position of the working unit by means of the control unit.

[0109] In step 230, a setpoint of a valve control parameter of a valve unit assigned to the hydraulic cylinder is determined as a function of the received setpoint of the motion parameter using a physical model and a data-based model (32; 32') by means of the control unit.

[0110] In step 240, a signal is output by the control unit depending on the determined setpoint of the valve control parameter in order to operate the working unit, in particular the attachment, of the, in particular mobile, working machine by operating the hydraulic cylinder.

[0111] If an embodiment includes an "and / or" connection between a first feature and a second feature, this is to be read as meaning that the embodiment according to one embodiment has both the first feature and the second feature, and according to another embodiment either only the first feature or only the second feature.

Claims

1. Method (100) for operating a hydraulic cylinder (26) of an, in particular mobile, working machine, comprising the following steps: - a target value (ṡR) of a movement parameter of the hydraulic cylinder (26) being received (110) by means of a control unit (10); - a target value (u) of a valve control parameter of a valve unit (24) assigned to the hydraulic cylinder (26) being determined (120) depending on the received target value (ṡR) of the movement parameter using a physical model (34; 34') and a data-based model (32; 32', 42') by means of the control unit (10), wherein the data-based model (32; 32', 42') and the physical model (34; 34') are part of pilot control of a controller used for determining the target value (u) of the valve control parameter; and - a signal being output (130) by means of the control unit (10) depending on the determined target value (u) of the valve control parameter in order to operate the hydraulic cylinder (26).

2. Method (100) according to Claim 1, characterized in that, in the step of determining (120) the target value (u) of the valve control parameter, - an output variable (Avlv,R) of the physical model (34; 34') is determined depending on the target value (ṡR) of the movement parameter, and - the target value (u) of the valve control parameter is determined depending on the determined output variable (Avlv,R) using the data-based model (42').

3. Method (100) according to Claim 2, characterized in that a target value for a valve parameter (Avlv,R; Qvlv,R) of the valve unit (24), in particular for a valve opening size (Avlv,R) or for a volume flow rate (Qvlv,R) assigned to the valve unit (24), is determined as the output variable (Avlv,R, Qvlv,R) of the physical model (34; 34').

4. Method (100) according to Claim 1, characterized in that, in the step of determining (120) the target value (u) of the valve control parameter, - an output variable of the data-based model is determined depending on the target value (ṡR) of the movement parameter, and - the target value (ṡR) of the valve control parameter is determined depending on the determined output variable using the physical model.

5. Method (100) according to Claim 4, characterized in that a target value for a valve opening size (Avlv,R) or for a volume flow rate (Qvlv,R) assigned to the valve unit (24) is determined as the output variable of the data-based model.

6. Method (100) according to Claim 1, characterized in that, in the step of determining (120) the target value (u) of the valve control parameter, - a first value (uFF,1) for an output variable is determined using the physical model (34), - a second value (uFF,2) for the same output variable is determined using the data-based model (32), and - the target value (u) of the valve control parameter is determined based on a comparison of the first and the second value (uFF,1, uFF,2).

7. Method (100) according to any of the preceding claims, characterized in that, in the step of determining (120) the target value (µ) of the valve control parameter, - a first value (uFF,1) for an output variable is determined using the physical model (34') and the data-based model (42'), - a second value (uFF,2) for the same output variable is determined using a further data-based model (32'), and - the target value (u) of the valve control parameter is determined based on a comparison of the first and the second value (uFF,1, uFF,2).

8. Method (100) according to any of the preceding claims, characterized in that - the working machine comprises at least one further hydraulic cylinder (26), - a further target value (ṡR) for a further movement parameter of the further hydraulic cylinder (26) is received by means of the control unit (10) in the receiving step (210a, 210b, 210c), - a further target value (u) of a further valve control parameter of a further valve unit (24) assigned to the further hydraulic cylinder (26) is determined by means of the control unit (10) depending on the received further target value (ṡR) using a further physical model (34; 34') and a further data-based model (32; 32') in the determining step (220a, 220b, 220c), wherein o a first value (uFF,1) for an output variable for the hydraulic cylinder (26) is determined using the physical model (34; 34') and the data-based model, o a further first value (uFF,1) for a further output variable for the further hydraulic cylinder (26) is determined using the further physical model (34; 34') and the further data-based model, o a respective second value (uFF,2) for the output variable of the hydraulic cylinder (26) and the further output variable of the further hydraulic cylinder (26) is determined using an additional data-based model (32; 32'), and o the respective target value (u) of the valve control parameters is determined based on a comparison of the respectively first and the respectively second value (uFF,1, uFF,2), and - the signal is output depending on the determined target values (u) of the valve control parameters in the output step (130) in order to operate the hydraulic cylinders (26).

9. Method (100) according to any of the preceding claims, characterized in that the target value (u) of the valve control parameter is determined using a speed controller (18), wherein the speed controller (18) comprises pilot control based on the physical model (34; 34') and the data-based model (32; 32', 42').

10. Method (200) for operating a working unit operable by means of a hydraulic cylinder (26), in particular an attachment, of an, in particular mobile, working machine, comprising the following steps: - a target position (xR) of the working unit, in particular the attachment, being received (210) by means of a control unit (10); - a target value (ṡR) of a movement parameter of the hydraulic cylinder (26) being determined (220) by means of the control unit (10) depending on the received target position of the working unit; - a target value (u) of a valve control parameter of a valve unit (24) assigned to the hydraulic cylinder (26) being determined (230) by means of the control unit (10) depending on the received target value (ṡR) of the movement parameter using a physical model (34; 34') and a data-based model (32; 32', 42'), wherein the data-based model (32; 32', 42') and the physical model (34; 34') are part of pilot control of a controller used for determining the target value (u) of the valve control parameter; and - a signal being output (240) by means of the control unit (10) depending on the determined target value (u) of the valve control parameter in order to operate the working unit, in particular the attachment, of the, in particular mobile, working machine by means of operating the hydraulic cylinder (26).

11. Control unit for operating a hydraulic cylinder (26) of an, in particular mobile, working machine, wherein the control unit is configured - to receive a target value (ṡR) of a movement parameter of the hydraulic cylinder (26), - to determine a target value (u) of a valve control parameter of a valve unit (24) assigned to the hydraulic cylinder (26) depending on the received target value (ṡR) of the movement parameter using a physical model (34; 34') and a data-based model (32; 32', 42'), wherein the data-based model (32; 32', 42') and the physical model (34; 34') are part of pilot control of a controller used for determining the target value (u) of the valve control parameter, and - to output a signal depending on the determined target value (u) of the valve control parameter in order to operate the hydraulic cylinder (26).

12. Control unit (10) for operating a working unit operable by means of a hydraulic cylinder (26), in particular an attachment, of an, in particular mobile, working machine, wherein the control unit (10) is configured - to receive a target position (xR) of the working unit, in particular the attachment, - to determine a target value (ṡR) of a movement parameter of the hydraulic cylinder (26) depending on the received target position of the working unit, - to determine a target value (u) of a valve control parameter of a valve unit (24) assigned to the hydraulic cylinder (26) depending on the received target value (ṡR) of the movement parameter using a physical model (34; 34') and a data-based model (32; 32', 42'), wherein the data-based model (32; 32', 42') and the physical model (34; 34') are part of pilot control of a controller used for determining the target value (u) of the valve control parameter, and - to output a signal depending on the determined target value (u) of the valve control parameter in order to operate the working unit, in particular the attachment, of the, in particular mobile, working machine by means of operating the hydraulic cylinder (26).

13. Working machine, in particular mobile working machine, comprising a working unit, in particular an attachment, at least one hydraulic cylinder (26) for moving the working unit, in particular the attachment, and a control unit (10) for operating the working unit, in particular the attachment, according to Claim 12.

14. Computer program comprising commands which, when executed by a computer or a control unit (10), cause the computer or control unit to execute and / or control the method (100) according to any of Claims 1 to 9 or the method (200) according to Claim 10.

15. Computer-readable data carrier on which the computer program according to Claim 14 is stored.