Method for providing a valve control parameter for a valve unit associated with a hydraulic cylinder of a working machine

Abstract

The invention relates to a method for providing a valve control parameter for a valve unit (24) associated with a hydraulic cylinder (26) of an, in particular mobile, working machine. The method has the following steps: - determining a setpoint value of the valve control parameter of the valve unit (24) as a function of a setpoint of a movement parameter of the hydraulic cylinder (26) using an assignment rule comprising at least two sub-models configured as local linear models, in order to provide the determined setpoint of the valve control parameter to operate the hydraulic cylinder (26); - reading-in actual values of the movement parameter and the valve control parameter acquired during operation of the hydraulic cylinder (26); - adapting at least one of the sub-models as a function of the read-in actual values; and - determining, by means of a computing unit (10), a further setpoint value of the valve control parameter as a function of a further setpoint of the movement parameter of the hydraulic cylinder (26) using the assignment rule with the adapted sub-model(s), in order to provide the determined further setpoint of the valve control parameter to operate the hydraulic cylinder (26).

Description

[0001] Description

[0002] title

[0003] Method for providing a one a valve unit

[0004] State of the art

[0005] The invention relates to a method and a computing unit for providing a valve control parameter of a valve unit assigned to a hydraulic cylinder of a work machine, in particular a mobile one. The present invention also relates to a system, a work machine, a computer program and a machine-readable storage medium.

[0006] Modern work machines increasingly enable the execution of 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. To model the physical relationships of a complex hydraulic system, purely data-based or hybrid control structures are used. This allows even nonlinear relationships within the system to be approximated with sufficient quality.

[0007] However, it has been found that even for machines from the same series, machine behavior changes continuously during operation due to production tolerances, environmental influences such as ambient temperature, air pressure, air quality, etc., and aging effects. These changes have a negative impact on the performance of the controller structures used and thus reduce, for example, the accuracy of following a specified TCP trajectory. This may require both an initial machine-specific calibration after production and a recalibration after a certain period of operation of the machine.

[0008] Disclosure of the invention

[0009] According to a first aspect, the present invention relates to a method for providing a valve control parameter of a valve unit assigned to a hydraulic cylinder of a, in particular mobile, work machine, in particular by means of a computing unit, according to claim 1.

[0010] The method comprises a step of determining a setpoint value of a valve control parameter of a valve unit assigned to the hydraulic cylinder as a function of a setpoint value of a movement parameter of the hydraulic cylinder using an assignment rule which comprises at least two submodels designed as local linear models in order to provide the determined setpoint value of the valve control parameter for operating the hydraulic cylinder, and in particular to operate the hydraulic cylinder based on the determined setpoint value of the valve control parameter.

[0011] The method further comprises a step of reading in actual values ​​of the movement parameter and the valve control parameter detected during operation of the hydraulic cylinder. The read-in actual values ​​preferably comprise at least one actual value of the movement parameter and at least one corresponding actual value of the valve control parameter. The actual values ​​of the movement parameter and the valve control parameter can be detected by one or more sensor units arranged on the working machine, in particular continuously, during operation of the hydraulic cylinder. The actual values ​​are preferably read in during operation of the hydraulic cylinder or the working machine.

[0012] The method also includes a step of adapting at least one of the submodels depending on the actual values ​​read in. In other words, in response to the actual values ​​of the movement parameter and the valve control parameter detected during operation of the hydraulic cylinder, one or more parameters of at least one of the submodels of the assignment rule are adapted, in particular, its value(s) are changed.

[0013] The method further comprises a step of determining a further setpoint value of the valve control parameter as a function of a further setpoint value of the movement parameter of the hydraulic cylinder using the assignment rule with the adapted submodel(s) by means of a computing unit in order to provide the determined further setpoint value of the valve control parameter for operating the hydraulic cylinder, and in particular to operate the hydraulic cylinder based on the provided further setpoint value of the valve control parameter. In other words, the same assignment rule is used to determine the setpoint value and to determine the further setpoint value, wherein at least one of the local linear models comprised by the assignment rule is adapted to determine the further setpoint value.

[0014] According to a second aspect, the present invention relates to a computing unit for providing a valve control parameter of a valve unit assigned to a hydraulic cylinder of a, in particular, mobile, work machine according to claim 10.

[0015] According to a third aspect, the present invention relates to a system comprising a hydraulic cylinder, a valve unit associated with the hydraulic cylinder, and a computing unit according to claim 11.

[0016] According to a fourth aspect, the present invention relates to a, in particular mobile, work machine according to claim 12.

[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 the computer or control unit to execute and / or control the steps of the method according to the first aspect of the invention, as well as a machine-readable storage medium on which the computer program is stored. The machine-readable or computer-readable storage medium can, for example, be a data carrier such as a semiconductor memory, a hard disk memory, or an optical memory.

[0018] The work machine can be a stationary or, preferably, a mobile work machine. The work machine can be a work machine for construction, agricultural, forestry, or logistics purposes. The mobile work machine can be, for example, an excavator, a wheel loader, a bulldozer, an industrial truck, a telehandler, or an aerial work platform. The stationary work machine can be, for example, a hydraulically driven industrial robot.

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

[0020] The attachment can be, for example, a bucket, a shovel, or a work basket. The attachment can be mounted on a work arm, a lifting frame, or a lifting mast of the work machine.

[0021] The work machine further comprises at least one hydraulic cylinder for moving the work unit. The hydraulic cylinder or hydraulic cylinder is designed to generate a relative movement between the work unit or the attachment and a main machine unit of the work machine. The main machine unit comprises, for example, an operator's cabin and / or a drive unit of the work unit. The main machine unit can be, for example, an uppercarriage of an excavator or a rear carriage of a wheel loader. The work unit or the attachment is therefore movable relative to the main machine unit of the work 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 pressurized hydraulic fluid, preferably a hydraulic liquid, and can in particular be inserted and removed from the housing.

[0022] The valve unit assigned to the hydraulic cylinder is designed to set a predetermined and / or predeterminable flow rate of the hydraulic fluid through the valve unit and / or to apply a predetermined and / or predeterminable pressure to the hydraulic fluid. The valve unit assigned to the hydraulic cylinder is designed to generate a relative movement between the piston and the housing of the hydraulic cylinder.

[0023] The valve unit can comprise one or more valves. The valve can be designed as a solenoid valve or a pneumatically actuated valve or pneumatic valve. The valve unit can comprise a pilot valve, in particular an electromagnetic one, and preferably a main valve, in particular a pneumatically actuated one, associated with the pilot valve.

[0024] 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 can generate a relative movement between the attachment and the main machine unit of the work machine, in particular between the attachment and a working arm and / or a lifting frame of the work machine, based on the arrangement of the hydraulic cylinder on the work machine.

[0025] In the context of the present invention, control can be understood as a control in the sense of generating an output variable based on an input variable. Control can furthermore and preferably be understood as a control comprising a closed-loop control in the sense of continuously determining an actual value of a variable to be controlled and continuously comparing the actual value with a setpoint value of the variable to be controlled.

[0026] The computing unit preferably comprises one or more, in particular cascaded, controllers. The computing unit can be arranged on the working machine. Alternatively, the computing unit can be arranged away from the working machine, for example, in a server backend or a cloud computing system, and can be connected to the working machine via a wireless communication link.

[0027] 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 a uniform or, preferably, uniformly accelerated movement.

[0028] The motion parameter of the hydraulic cylinder can be a speed and / or an acceleration. Preferably, the motion parameter is a relative speed and / or a relative acceleration between the piston and the housing of the hydraulic cylinder. The motion parameter can include a magnitude and a direction of the speed and / or acceleration.

[0029] In the context of the present invention, determining a setpoint can be understood as determining at least one setpoint. The setpoint is a predetermined and / or predeterminable value and / or a previously determined value. Preferably, determining the setpoint comprises determining a plurality or set of setpoints. It is conceivable that the plurality or set of setpoints represents a temporal sequence of setpoints. The setpoint of the movement parameter is accordingly a value or a temporal progression of the value of the movement parameter according to which a movement of the hydraulic cylinder is to occur.

[0030] It is conceivable that, in the step of determining the setpoint value of the movement parameter, a setpoint value of a movement parameter in the form of speed and, furthermore, a setpoint value of a further movement parameter in the form of acceleration of the hydraulic cylinder are determined. Alternatively or additionally, setpoints for further or higher time derivatives of the speed or acceleration of the hydraulic cylinder can be determined. It is also conceivable that one or more setpoints of one or more movement parameters of one or more further hydraulic cylinders are determined, wherein the one or more further hydraulic cylinders are assigned to the same valve unit as the hydraulic cylinder or are operated by means of the same valve unit.

[0031] The valve control parameter of the valve unit can be a parameter of one or more valves of the valve unit, based on which the valve(s) of the valve unit are controlled. The valve control parameter can be a valve current or a current strength of a solenoid valve. The valve control parameter can also be a pressure by means of which a pneumatically actuated valve is actuated. The valve control parameter can furthermore be a geometric and / or fluidic valve parameter, such as an opening area of ​​a valve orifice of a valve of the valve unit. It is also conceivable that the valve control parameter is a position of an operating element, in particular a joystick, of the work machine. The operating element can serve as a means for controlling the movement of the hydraulic cylinder. The position of the operating element of the work machine can be a position or a state of the operating element. Depending on the position or the position orThe valve unit assigned to the hydraulic cylinder is controlled by the control element's state 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 state of the valve unit.

[0032] In the context of the present invention, an assignment rule can be understood as a rule that maps the setpoint of the movement parameter to the setpoint of the valve control parameter. The assignment rule is preferably part of a feedforward control of a controller, in particular a speed controller, used to determine the setpoint of the valve control parameter. Thus, the proposed method can be designed as a method for speed control of the hydraulic cylinder, which enables adaptation of the at least one local linear model during operation of the hydraulic cylinder or during operation of the work machine. The assignment rule comprises at least two submodels, which are designed as local linear models.In the context of the present invention, a local linear model can be understood as a data-based model that is configured to map an input variable comprising at least one value of the movement parameter of the hydraulic cylinder to a value of the valve control parameter. For example, the input variable can comprise a value each of a speed and an acceleration of the hydraulic cylinder. Furthermore, the input variable can comprise one or more further parameters of the hydraulic cylinder and / or the working machine, e.g., pressure and / or temperature of a hydraulic fluid of the hydraulic cylinder, engine speed of the working machine, and / or a difference between a load pressure of the working unit and a pressure provided by a pump unit for pressurizing the hydraulic fluid.

[0033] There is a linear relationship between the input variable and the output variable (linearity property). The submodels encompassed by the mapping rule and designed as local linear models are preferably configured to map target values ​​of the motion parameter to target values ​​of the valve control parameter. In other words, the submodels have the same input variable space and the same output variable space.

[0034] Furthermore, a weighting of the output variable of the local linear model depends on the input variable (locality property). In particular, to determine the target value of the valve control parameter as a function of a target value of the motion parameter, a weighted sum of the output variables of the local linear models is determined, wherein a weighting function for determining the weighted sum preferably depends on the target value of the motion parameter. In other words, in different value ranges of the input variable, different linear models are more dominant with regard to the determined target value of the valve control parameter. In this case, the weighting function can additionally or alternatively depend on a value of one or more other parameters, e.g., pressure or temperature. Typical examples of local linear models are "Local Linear Model Trees" (LoLiMoT for short) or "Rectified Linear Unit-based Local Linear Model Tree" (ReLuMot for short).Local linear models differ from artificial neural networks in key aspects: Training of local linear models is purely deterministic. The number of parameters required for local linear models is typically smaller. In particular, continuous online updates of local linear models are possible both in the cloud and on embedded systems. Furthermore, local linear models are particularly well suited for low-dimensional input variables.

[0035] Local linear models are preferably trained using the entirety of the available training data. However, this involves weighted training, meaning that individual training data, comprising values ​​of motion parameters and valve control parameters, affect the various local linear models to varying degrees. This effect or influence correlates with a distance to a center of the local model and can also be interpreted as the affiliation of the respective input variable, comprising the motion parameter u and / or one or more other parameters, to the i-th local linear model LLM. t with where m denotes the total number of local linear models encompassed by the assignment rule. Any kernel function, e.g., a Gaussian function, can be used as a membership function 0(... ) representing the membership.

[0036] The mapping rule may further represent one or more physical models and / or one or more data-based models for mapping the setpoint value of the motion parameter to the setpoint value of the valve control parameter.

[0037] The data-based model can be a mathematical model or a mathematical 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. 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 nonlinear component of the model, in particular a component of the model that is significantly dependent on a load acting on the work unit.

[0038] The physical model can be a mathematical model or a mathematical algorithm designed to map an input variable to an output variable 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 variable and the output variable. Following the nomenclature of systems theory, the physical model can also be referred to as a white box model.

[0039] 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.

[0040] Advantageously, the (further) setpoint value of the valve control parameter is further determined as a function of, in particular a value of, at least one further parameter of the hydraulic cylinder and / or the working machine. The further parameter is preferably a parameter different from the movement parameter. The further parameter can also correspond to a time derivative of the movement parameter. The further parameter can be a pressure, e.g., a pressure of a hydraulic fluid of the hydraulic cylinder. The further 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 further 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 a hydraulic fluid in the hydraulic cylinder. It is also conceivable that the additional parameter is the speed of a motor of the working machine. In other words, one or more of the values ​​described above can represent additional input variables for the local linear models.

[0041] Determining the target value of the valve control parameter can be preceded by a step of providing, in particular determining, the target value of the movement parameter of the hydraulic cylinder. Preferably, the target value of the movement parameter is determined as a function of a provided target position of a working unit of the, in particular, mobile, work machine.

[0042] A target position of the work unit can be a spatial relative position of the work unit relative to the work machine comprising the work unit or a spatial position in an external reference coordinate system, e.g., 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 tool center point (TCP) of the attachment. The target position of the work unit or attachment can be specified, for example, for a work step of a work process to be carried out by the work machine. The target position of the attachment can also include a spatial orientation of the attachment, e.g., relative to the main machine unit of the work machine.

[0043] The target value of the motion parameter can be determined based on the target position of the work unit using software-based trajectory planning for the work unit, the attachment, or the work machine. The target value of the motion parameter can be determined taking into account at least part of the kinematics of the work machine.

[0044] Providing the determined (further) setpoint value may include outputting a signal representing, indicating, or encompassing the determined (further) setpoint value. Based on the output signal, the valve unit and / or the hydraulic cylinder can be operated, in particular controlled, directly or indirectly.

[0045] The proposed method enables efficient, machine-specific compensation for changes in the behavior of (partially) automated work machines during regular fleet operation caused by production tolerances, environmental influences, and aging effects. The proposed approach enables online adaptation of the assignment rule used to determine the setpoint of the valve control parameter, which can also be performed on control units with low memory and computing capacity, e.g., on an embedded system. This permanently ensures the performance of the assignment rule, especially of the controller structures used, and thus the accuracy when following a specified TCP trajectory.By using local linear models, even a complex system behavior of the working machine with limited computing resources can be efficiently mapped during operation and thus a control structure can be provided with a current representation of the system behavior.

[0046] It is advantageous if the submodels included in the assignment rule used to determine the target value of the valve control parameter were trained based on training data acquired during operation of the and / or another hydraulic cylinder of the and / or another, in particular mobile, work machine. The additional work machine is, in particular, a reference work machine different from the work machine.

[0047] Training preferably takes place before operating the hydraulic cylinder or the work machine, for example, during or immediately after a production phase of the work machine. For training, the training data can be generated, for example, using a method known to those skilled in the art from DE 10 2021 214 049 A1 and / or reduced using a method known to those skilled in the art from DE 10 2021 214 042 A1. In other words, for offline training, specially prepared training data is generated based on a representative vehicle, allowing the best possible coverage of all possible operating ranges (design of experiment). This so-called initial model serves as the basis for further adaptation, for example by the customer or end user, in order to approximate the specific properties or characteristics of the respective machine online.

[0048] This design enables offline training before commissioning of the cylinder or the working machine, whereby the adaptation of the submodels according to the proposed method can be carried out within defined limits of an offline predefined range and thus stability problems are avoided.

[0049] It is also advantageous if the method comprises a step of selecting the at least one submodel to be adapted based on the read-in actual values ​​of the movement parameter and the valve control parameter, in particular by means of the computing unit. It is conceivable that one, several, or all submodels encompassed by the assignment rule are selected. Preferably, the at least one submodel to be adapted is selected based on the read-in actual value of the movement parameter and independently of the actual value of the corresponding valve control parameter. By adapting only selected submodels, the computational complexity of the method can be further reduced.

[0050] It is further advantageous if the method comprises a step of determining a membership parameter, in particular by means of the computing unit, which represents the association of the read-in actual value of the motion parameter with the submodels of the assignment rule in order to select the at least one submodel to be adapted based on the determined membership parameter. The membership parameter is preferably based on a distance, weighted, for example, by means of a Gaussian function, between the actual value of the motion parameter and a reference value for actual values ​​of the motion parameter, in particular a center relative to the actual values ​​of the motion parameter, of the respective local linear model.

[0051] According to one embodiment, each dimension of the motion parameter, e.g., a dimension of cylinder velocity and a dimension of cylinder acceleration, is halved several times, in particular, in order to divide a value range of the motion parameter into respective sub-value ranges and to assign one of the sub-value ranges to each of the local linear models. Within each of the sub-value ranges, a center, e.g., a geometric center, can be defined, which serves as a reference point or reference value for determining the membership parameter for the respective local linear model.

[0052] This design allows the submodel(s) to be selected to be calculated numerically particularly efficiently, so that the method can also be executed in real time on embedded systems with limited computing resources.

[0053] Alternatively, it is advantageous if, in the step of adapting the at least one submodel, one or more mapping parameters of the submodel are adapted, wherein a number of submodels and / or a mapping between value ranges of the motion parameter and the submodels are maintained. In other words, in the step of adapting, the number of submodels encompassed by the mapping rule and / or the mapping between the value ranges of the motion parameter and the submodels are not changed.Here, it is assumed that there is a difference between the current behavior of the system and the nominal behavior of the system (and thus the adaptation of at least one submodel is necessary), but at the same time, the difference is limited to such an extent that a re-determination of the number of submodels and / or a mapping between the value ranges of the motion parameter and the local linear models is not necessary. This design allows the method to be implemented with particularly low computational effort.

[0054] It is furthermore advantageous if, in the step of adapting the at least one submodel, one or more mapping parameters of the submodel and furthermore a number of submodels and / or an assignment between value ranges of the movement parameter and the submodels are adapted. In other words, in the step of adapting, the number of submodels encompassed by the assignment rule and / or the assignment between the value ranges of the movement parameter and the submodels are additionally changed. It is conceivable that a number of submodels is increased or decreased. It is also conceivable that, alternatively or additionally, an assignment between value ranges of the movement parameter and at least two of the submodels is changed. This embodiment can further improve the accuracy of the method.

[0055] It is also advantageous if the at least one submodel is only adapted if a deviation between the determined target value of the movement parameter and the corresponding actual value of the movement parameter is greater than or equal to a threshold value and / or less than or equal to a maximum value.

[0056] The threshold value and / or the maximum value can be a predefined or predefinable value. It is conceivable that in the adjustment step, the deviation between the determined target value of the movement parameter and the corresponding actual value of the movement parameter is first determined and then a comparison is made with the threshold value and / or the maximum value in order to decide, based on the comparison, whether an adjustment of one of the submodels is necessary at all. In the event that an adjustment is necessary based on the comparison, the at least one submodel to be adjusted can be selected, for example, based on the membership parameter to be determined.This design ensures that the submodel is only adjusted when necessary, without taking into account drastic deviations between actual and target values, particularly those resulting from operating the machine outside of a specified operating range. Thus, the submodel is adjusted when an improvement in the controller is possible, while actual values ​​from extreme operation of the machine are disregarded.

[0057] It is further advantageous if the at least one adapted submodel is provided in a stationary state of the hydraulic cylinder for determining the further setpoint. The stationary state can represent a standstill or a rest phase of the hydraulic cylinder, for example in a stationary state, in particular a standstill or a rest phase, of the working machine. In this case, the adaptation of the at least one submodel can take place before, for example during a movement of the hydraulic cylinder and / or the working machine, or in the stationary state. For example, one or more adapted mapping parameters of the local linear models can be determined continuously, but the adapted submodel can only be provided for determining the further setpoint when the hydraulic cylinder and / or the working machine are in a stationary state.Alternatively, the at least one adapted submodel can be provided, particularly immediately after the adaptation step, independently of the state of the hydraulic cylinder and / or the working machine for determining the further setpoint. This configuration allows an online update of the assignment rule to be made dependent on the operating state of the hydraulic cylinder and / or the working machine by adapting one or more of the local linear models.

[0058] It is further advantageous if the method comprises a step of outputting a signal to the valve unit, in particular by means of the computing unit, as a function of the determined setpoint value and / or the determined further setpoint value of the valve control parameter, in order to control the valve unit in response to the output signal and, in particular, to operate or move the hydraulic cylinder by controlling the valve unit. By operating the hydraulic cylinder, the working unit, in particular the attachment, of the, in particular mobile, work machine can in turn be operated. The output signal can be a wired or wireless signal transmitted directly or indirectly from the computing unit to the valve unit.

[0059] Drawings

[0060] The invention is explained in more detail below with reference to the accompanying drawings. They show:

[0061] Fig. 1 is a schematic representation of a control unit for

[0062] Operating a work unit of a work machine; and

[0063] Fig. 2 is a flowchart of a method for providing a

[0064] Valve control parameter of a valve unit assigned to a hydraulic cylinder of a working machine.

[0065] Fig. 1 shows a schematic representation of a control unit 10 for operating a working unit of a work machine, in particular a mobile work machine, operable by means of a hydraulic cylinder 26. The work 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 work machine.

[0066] The work machine can, for example, be an excavator comprising a working unit configured 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.

[0067] The control unit 10 is set up to set a target position r R of the work unit. The target position r R further include information regarding a spatial orientation of the work unit. For example, the control unit 10 can be configured to receive spatial target coordinates of a tool center point (TCP) of the excavator's bucket as well as an angle of the bucket relative to a predetermined reference direction.

[0068] The target position r Rcan be part of a target trajectory of the work unit. It is conceivable that the target trajectory is determined by an operator of the work machine and / or by means of a computing unit 12 for generating a target trajectory for the work machine and provided to the control unit 10.

[0069] The target position r is preferred R of the working unit is provided to a pose module 14 of the control unit 10. The pose module 14 is preferably designed as part of a cascade controller and is configured to determine the target position r R of the work unit and further to receive the actual position r of the work unit from a sensor unit 28 detecting the actual position r of the work unit. Furthermore, the pose module 14 is configured to receive, based on a deviation from the target position r R and actual position r of the working unit a target speed r R of the work unit by means of which the actual position r is converted to the target position rR For example, the pose module 14 is used to determine the target position r R of the TCP and the actual position r of the TCP and based on the deviation a target speed r R of the TCP. The pose module 14 can also be configured based on the deviation from the target position r R and actual position r of the working unit or the determined target speed r R a target acceleration r R of the work unit.

[0070] The control unit 10 comprises a differential inverse kinematics module 16 which is configured to, based on the target speed r R the work unit a setpoint s R a movement parameter of the hydraulic cylinder 26. Determining the setpoint s RThe motion parameter is preferably determined taking into account the kinematics of the working unit of the working machine, in particular by solving the inverse kinematic problem for the working machine. For example, based on the target speed r R of the TCP of the excavator each have a target speed s R for the boom cylinder, the stick cylinder and the bucket cylinder. For example, the setpoint s R of the movement parameter of the hydraulic cylinder 26 a target speed s R of the hydraulic cylinder 26. It is conceivable that the inverse kinematics module 16 is also set up, alternatively or additionally, to determine a target acceleration s R of the hydraulic cylinder 26 as the target value of a, in particular further or additional movement parameter.

[0071] The control unit 10 is also configured to determine, by means of a speed module 18, a setpoint u of a valve control parameter of the valve unit 24 as a function of the setpoint s R of the movement parameter of the hydraulic cylinder 26.

[0072] The speed module 18 is preferably designed as a speed controller 18 and is configured to set the setpoint s R of the motion parameter and the actual value s R of the movement parameter of the hydraulic cylinder 26, preferably also the setpoint s R of the further motion parameter. Furthermore, the speed module 18 is configured to calculate the speed based on a deviation between the setpoint s R and the actual value s of the movement parameter to determine the setpoint u of the valve control parameter.

[0073] Preferably, the speed module 18 is configured to additionally take into account one or more of the following influencing variables when determining the setpoint u of the valve control parameter:

[0074] Actual value s and / or setpoint s R an acceleration of the hydraulic cylinder 26 and / or one or more other hydraulic cylinders assigned to the same valve unit 24,

[0075] Actual value of a pressure on a cylinder rod of the hydraulic cylinder 26,

[0076] Actual value of a pressure at a cylinder head of the hydraulic cylinder 26, difference p cyi between the actual value of the pressure at the cylinder rod and the actual value of the pressure at the cylinder head 26, actual value of a load pressure of the working unit,

[0077] Actual value of a pump pressure of a pump unit assigned to the hydraulic cylinder 26 for pressurizing a hydraulic fluid moving the hydraulic cylinder 26, difference An™ between the actual value of the load pressure and the actual value of the pump pressure,

[0078] Actual value of an ambient temperature and / or an engine oil in an oil circuit of the working machine.

[0079] The speed module 18 preferably comprises a PI controller with a feedforward control 18a. This allows the PI controller to be relieved of its load, even in the case of complex and nonlinear behavior, so that its feedback control 18b only needs to consider disturbances and model errors.

[0080] The pilot control 18a represents an inverse behavior of the working unit regarding the relationship between the movement parameter of the hydraulic cylinder 26 and the valve control parameter of the respective valve unit 24. In other words, the pilot control 18a determines a value u of the movement parameter of the hydraulic cylinder 26 based on a predetermined value of the valve control parameter. Here, the precontrol 18a is carried out using an assignment rule that includes at least two submodels embodied as local linear models. At least one of the local linear models included in the assignment rule is adapted according to the method described with reference to Fig. 2 during operation of the hydraulic cylinder 26 or the working machine.

[0081] For the excavator with boom cylinder, stick cylinder, and bucket cylinder, the control unit 10 includes a speed module 18 configured as a PI controller for determining a setpoint u of the valve control parameter for the valve unit assigned to the respective cylinder. Each of the PI controllers includes its own pilot control 18a.

[0082] The setpoint u of the valve control parameter is output as a manipulated variable of the speed module 18. Here, the setpoint u of the valve control parameter is in particular a sum of an output variable u FB the feedback 18b and an output variable u FF the pilot control 18a. The control unit 10 is further configured to output the determined setpoint u of the valve control parameter to the system 20. The system 20 comprises a control module 22, the valve unit 24, and the hydraulic cylinder 26. The system 20 represents a controlled system of the speed controller 18.

[0083] 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 a 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. In other words, by outputting the signal to the valve unit 24 as a function of the determined target value u of the valve control parameter, the hydraulic cylinder 26 is operated and thus the working unit is moved.

[0084] One or more of the sensors 28 arranged on the working machine are designed to measure the actual position r of the working unit, an actual position or actual position s of the hydraulic cylinder 26, and preferably the above-mentioned influencing variables, in particular ss, p cyh p systo measure. Suitable model-based filters 30 are preferably assigned to the sensors 28.

[0085] The model-based filters 30 are configured to output the actual position r of the working unit to the pose module 14 and to the inverse kinematics module 16, to output the actual position or actual position s of the hydraulic cylinder 26 to the inverse kinematics module 16, and preferably the above-mentioned influencing variables, in particular ss, p cyh p sys to the speed module 18.

[0086] Fig. 2 shows a flowchart of a method for providing a valve control parameter of a valve unit assigned to a hydraulic cylinder of a work machine, in particular a mobile one. The method is designated in its entirety by reference numeral 100.

[0087] Preferably, the method 100 is carried out during operation of the work machine, for example during processing and / or treatment of an agricultural and / or forestry and / or construction area and / or during transport of a load.

[0088] The method 100 is preferably carried out by a control unit of the work machine. For this purpose, the control unit comprises a processor, a storage medium with a computer program, and at least one communication interface. The computer program comprises instructions which, when executed by the processor, cause the control unit to execute the method 100 described below.

[0089] The method 100 comprises a step 110 of determining a setpoint u of a valve control parameter of a valve unit assigned to the hydraulic cylinder as a function of a setpoint s R ,s Rof a movement parameter of the hydraulic cylinder using an assignment rule to provide the determined setpoint value of the valve control parameter for operating the hydraulic cylinder. The assignment rule comprises at least two submodels LLM1, LLM2 designed as local linear models LLM1, LLM2. To determine the setpoint value u of the valve control parameter, a weighted sum of the output variables u1, u2 of the local linear models LLM1, LLM2 is determined, wherein a weighting function O(s R ,s R ) to determine the weighted sum for m local linear models of the target value of the motion parameter s R ,s R depends:

[0090] In other words, during inference, predictions are performed with all m local linear models, with the prediction of the overall model being determined by a weighted average of all predictions of the local models. In addition or alternatively to the target value s R ,s R of the movement parameter, one or more additional parameter values, e.g. selected from the influencing variables described above, can be taken into account.

[0091] The method 100 includes a step 120 of outputting a signal to the valve unit as a function of the determined target value of the valve control parameter. In response to the output signal, the valve unit is controlled and the hydraulic cylinder is thus operated based on the determined target value of the valve control parameter. During operation of the hydraulic cylinder, actual values ​​of the movement parameter and the valve control parameter are recorded.

[0092] The method 100 comprises a step 130 of reading in the actual values ​​of the movement parameter and the valve control parameter detected during operation of the hydraulic cylinder.

[0093] The method 100 comprises a step 140 of adapting at least one of the submodels of the assignment rule depending on the read-in actual values ​​of the movement parameter and the valve control parameter.

[0094] The step 140 of adaptation comprises a step 142 of determining a membership parameter ij, which defines an affiliation of the read-in actual value of the movement parameter to the submodels LLM t The membership parameter ij can be defined, for example, as a distance to a center of the respective local linear model LLM t be determined:

[0095] Here, m denotes the total number of local linear models encompassed by the assignment rule. A membership function representing the membership is 9 s R ,s R ), for example, a Gaussian function can be used.

[0096] The adaptation step 140 further comprises a step 144 of selecting the at least one submodel to be adapted based on the read-in actual values ​​of the movement parameter and the valve control parameter, in particular based on the determined membership parameter, optionally taking into account one or more further parameters, for example, selected from the influencing variables described above. Preferably, the submodel(s) selected as the submodel(s) to be adapted are those for which the membership parameter Hi exceeds a predefined or predefinable threshold value E.

[0097] The adaptation step 140 further comprises a step 146 of adapting one or more mapping parameters of the at least one submodel to be adapted. The adaptation of the mapping parameters can be performed, for example, using a least-squares method known to those skilled in the art, for example, using a recursive least-squares algorithm.

[0098] In this case, the number of submodels and the mapping between the value ranges of the motion parameter and the local models are maintained. The model type of the submodels, the number of submodels, the mapping between the value ranges of the motion parameter and the local models, and the weighting of the output variables of the local linear models are preferably defined or determined during offline training.

[0099] For offline training, specially prepared training data sets can be generated on a representative working machine, allowing the best possible coverage of all possible operating ranges (design of experiment). This allows the assignment rule with the local linear models trained based on these training data sets to be provided as the initial assignment rule for step 110. In other words, the initial assignment rule can serve as the basis for further adaptation by a customer or end user of the working machine, so that specific properties or characteristics of the respective machine, particularly those due to production tolerances, environmental influences, and aging effects, can be approximated online.

[0100] The method 100 comprises a step 150 of determining a further setpoint value of the valve control parameter as a function of a further setpoint value of the movement parameter of the hydraulic cylinder using the assignment rule with the adapted submodel(s) in order to provide the determined further setpoint value of the valve control parameter for operating the hydraulic cylinder. The method 100 comprises a step 160 of outputting a further signal as a function of the determined further setpoint value of the valve control parameter to the valve unit in order to control the valve unit in response to the outputted further signal and thus operate the hydraulic cylinder based on the determined further setpoint value of the valve control parameter. Once again, actual values ​​of the movement parameter and the valve control parameter are recorded during operation of the hydraulic cylinder.

[0101] Preferably, the method continues in step 130.

Claims

Claims 1 . Method (100) for providing a valve control parameter of a valve unit (24) associated with a hydraulic cylinder (26) of a, in particular, mobile, work machine, comprising the following steps: - determining (110) a setpoint value of the valve control parameter of the valve unit (24) as a function of a setpoint value of a movement parameter of the hydraulic cylinder (26) using an assignment rule which comprises at least two submodels designed as local linear models in order to provide the determined setpoint value of the valve control parameter for operating the hydraulic cylinder (26); - reading (130) actual values ​​of the movement parameter and the valve control parameter detected during operation of the hydraulic cylinder (26); - adapting (140) at least one of the submodels depending on the actual values ​​read in; and - determining (150) a further setpoint value of the valve control parameter as a function of a further setpoint value of the movement parameter of the hydraulic cylinder (26) using the assignment rule with the adapted submodel(s) by means of a computing unit (10) in order to provide the determined further setpoint value of the valve control parameter for operating the hydraulic cylinder (26).

2. Method (100) according to claim 1, characterized in that the submodels included in the assignment rule used to determine (110) the setpoint value of the valve control parameter were trained based on training data acquired during operation of the and / or a further hydraulic cylinder (26) of the and / or a further, in particular mobile, work machine.

3. Method (100) according to claim 1 or 2, characterized by a step of selecting (144) the at least one Submodel based on the read actual values ​​of the motion parameter and the valve control parameter.

4. The method (100) according to claim 3, characterized by a step of determining (142) a membership parameter which represents an association of the read-in actual value of the movement parameter to the submodels of the assignment rule in order to select the at least one submodel to be adapted based on the determined membership parameter.

5. Method (100) according to one of the preceding claims, characterized in that in the step of adapting (140) the at least one submodel, one or more mapping parameters of the submodel are adapted, wherein - a number of submodels and / or - an assignment between value ranges of the movement parameter and the submodels is maintained.

6. Method (100) according to one of claims 1 to 4, characterized in that in the step of adapting (140) the at least one submodel, one or more mapping parameters of the submodel and further - a number of submodels and / or - an assignment between value ranges of the movement parameter and the submodels can be adjusted.

7. Method (100) according to one of the preceding claims, characterized in that the at least one submodel is only adapted if a deviation between the determined target value of the movement parameter and the corresponding actual value of the movement parameter - is greater than or equal to a threshold, and / or - is less than or equal to a maximum value.

8. Method (100) according to one of the preceding claims, characterized in that the at least one adapted submodel is provided in a stationary state of the hydraulic cylinder (26) for determining the further target value.

9. Method (100) according to one of the preceding claims, characterized by a step of outputting (120, 160) a signal as a function of the determined setpoint value and / or the determined further setpoint value of the valve control parameter to the valve unit (24) in order to control the valve unit (24) in response to the output signal.

10. A computing unit (10), in particular a control unit (10), for providing a valve control parameter of a valve unit (24) assigned to a hydraulic cylinder (26) of a, in particular mobile, work machine, wherein the computing unit (10) is configured to execute and / or control the steps of the method (100) according to one of claims 1 to 9.

11. System comprising a hydraulic cylinder, a valve unit (24) associated with the hydraulic cylinder (26), and the computing unit (10) according to claim 10.

12. Work machine, in particular mobile work machine, with a system according to claim 11.

13. A computer program comprising instructions which, when executed by a computer or a control unit (10), cause the computer or control unit (10) to carry out and / or control the steps of the method (100) according to any one of claims 1 to 9.

14. A machine-readable storage medium on which the computer program according to claim 13 is stored.

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