CONTROL METHOD FOR A PARTS ELECTRONIC SYSTEM

Description

[0001] The invention relates to a control method for a partially electronic system, such as an electro-hydraulic system, having the features in the preamble of claim 1.

[0002] DE 10 2017 004 299 A1 discloses a device for speed control and synchronization control of hydraulic actuators, which in particular control parts of transport devices that are movable relative to one another, consisting of: at least one actuator, such as a hydraulic working cylinder; a working pump in the form of a fixed displacement pump for supplying the actuator; a switching valve as a valve switching device for the actuator; an electric drive forming an electro-proportional actuator for the working pump; a position measuring system for determining the actual position of the actuator; and a frequency converter with a drive controller for carrying out a control method, which receives measured values ​​from the position measuring system as input variables and uses its output variables to control the speed of the electric drive and thereby the power of the working pump.

[0003] DE 10 2016 214 708 A1 describes a control method and a control system for a partially electronic system, such as an electro-hydraulic system, with the steps in the preamble of claim 1 or 11 with at least one electro-proportional actuator which, depending on its manipulated variable, serves to influence at least one physical controlled variable of the system having a controlled system, wherein a characteristic map is created from correlating state values ​​of the manipulated variable and the controlled variable, which map is used for control processes in the subsequent operation of the system.

[0004] Further control methods can be found in KR 10-1839039 B1, EP 2 853 752 A1 and DE 10 2013 206 973 A1.

[0005] The invention is based on the object of further improving the known control method for a partially electronic system in such a way that a desired value of a controlled variable of the system is adjusted as quickly as possible with little effort.

[0006] This object is achieved by a control method comprising the method steps of patent claim 1 in its entirety.

[0007] According to the characterizing part of claim 1, the control method according to the invention is characterized in that, in order to create the characteristic map, the value of the manipulated variable is increased in two phases in a sawtooth shape, initially during a first time period until saturation of the controlled variable value y(t) is determined and is subsequently reduced during a second time period which is shorter than the first time period.

[0008] It is also planned that a characteristic map will be created from correlating state values ​​of the manipulated and controlled variables, which will be used for control processes in the later operation of the system.

[0009] As a result, when the system is operated using the characteristic map and specifying the desired controlled variable value, the actuator can be controlled with a manipulated variable value that causes the controlled variable to be immediately adjusted to the desired controlled variable value. With a control method designed in this way, in contrast to the prior art, there is no need for time-consuming adjustment of the controlled variable during a transient phase due to a continuous change in the manipulated variable value, taking into account a measured and fed-back controlled variable value, until the desired actual controlled variable value is achieved. For this purpose, the characteristic map only needs to be determined once before commissioning the controlled system, and this map can be used multiple times for control processes during system operation. This has no equivalent in the prior art.

[0010] The invention also relates to an electrohydraulic system for carrying out a control method according to claim 11. The system consists of at least one pressure supply device, a controlled system with a hydraulic consumer, and an electroproportional actuator in the form of a proportional valve, which can be controlled by a controller which receives current state values ​​of a controlled variable of the controlled system via a sensor device.

[0011] Further advantages of the solutions according to the invention are the subject of the subclaims.

[0012] In the following, a control method according to the invention is explained in more detail using the electrohydraulic system according to the invention and with the aid of the drawing. In this case, the following are shown in a schematic and non-authoritative representation: Fig. 1 shows the control method according to the invention in the form of a block diagram; Fig. 2 shows, in a Cartesian coordinate system, the temporal progression of a manipulated variable and a controlled variable dependent on the manipulated variable during the determination of a characteristic map comprising control and controlled variable value combinations as part of the control method; Fig. 3 shows, in the form of a hydraulic circuit diagram, a first exemplary embodiment of a system according to the invention for carrying out the control method according to the invention, in which the controlled variable corresponds to the speed of a hydraulic motor; Fig. 4 shows, in the form of a hydraulic circuit diagram, a second exemplary embodiment of the system according to the invention, in which the controlled variable corresponds to the speed of a hydraulic motor; Fig. 5 shows, in a Cartesian coordinate system, progressions of the actual and the measured controlled variable in the form of the speed of the hydraulic motor of the first exemplary embodiment from Fig. 3 or the second embodiment from Fig. 4 ; Fig. 6, in the form of a hydraulic circuit diagram, shows a third exemplary embodiment of the system according to the invention, in which the controlled variable corresponds to the supply pressure value at a consumer; and Fig. 7, in the form of a hydraulic circuit diagram, shows a fourth exemplary embodiment of the system according to the invention, in which the controlled variable corresponds to the supply pressure value at a consumer.

[0013] The Fig. 1 shows a block diagram of the control method according to the invention for a partially electronic system 110, such as an electro-hydraulic system 110. The partially electronic system 110 has a controlled system 112 and an electro-proportional actuator 114 for influencing a physical controlled variable y(t) of the system 110 as a function of a manipulated variable u(t).

[0014] In a first method step, before commissioning of the system 110, a characteristic map 116 is created from correlating state values ​​of the manipulated variable u(t) and the controlled variable y(t), the state values ​​of which are used in a second method step during operation of the system 110 for a control process of the system 110 in the form of a targeted adjustment of a static state of the controlled system 112 of the system 110.

[0015] The characteristic map 116 can be determined each time before commissioning or once before several commissionings of the controlled system 112 or after maintenance of the controlled system 112 or after replacement of a component of the controlled system 112.

[0016] The characteristic map 116, which in this case comprises value pairs of the manipulated variable u(t) and the controlled variable y(t), is two-dimensional, but can also be three-dimensional if expanded to include another variable. The characteristic map 116 is designed as a table or matrix and assigns determined discrete values ​​of the controlled variable y(t) to predetermined discrete values ​​of the manipulated variable u(t). Such a characteristic map 116 can also be referred to as a lookup table (LUT) or conversion table.

[0017] If only one control 18 having the characteristic map 116 is provided, the target controlled variable value y s ( t ) , whose adjustment is desired, is fed exclusively to the controller 18. The discrete manipulated variable value u(t), which in the characteristic map 116 corresponds to the desired controlled variable value specified to the controller 18 y s ( t) is fed by the controller 18 to the actuator 114, which acts accordingly on the controlled variable y(t) of the controlled system 112.

[0018] If the control 18 having the characteristic map 116 is superimposed in the sense of a feedforward control by a control 19 for compensating disturbance variables, as in Fig. 1 shown, the reference variable is the target controlled variable value y s ( t ), whose adjustment is desired, is fed equally to the controller 18 and a first summation point 20. The discrete manipulated variable value u v ( t ), which in the characteristic map 116 corresponds to the target controlled variable value specified by the controller 18 y s ( t ) is fed by the controller 18 to a second summation point 22. In addition to the specified target controlled variable value, the first summation point 20 is y s ( t ) the measured actual controlled variable value y m ( t). The first summation point 20 determines the difference between the specified target controlled variable value y s ( t ) and the measured actual controlled variable value y m ( t ), i.e. the controlled variable value deviation e y ( t ), which is fed to a controller 25 of the control system 19, in particular a PID controller 25. The controller 25 determines based on the controlled variable value deviation e y ( t ) a control variable value deviation e u ( t ) and feeds it to the second summation point 22. The second summation point 22 feeds the sum of its input values, namely the disturbance-corrected manipulated variable value u(t), to the actuator 114, which accordingly acts on the controlled variable y(t) of the controlled system 112.

[0019] The control 18 and the control 19 superimposed on the control 18 together form a control.

[0020] For the automated creation of the characteristic map 116, the manipulated variable value u(t), represented by a dashed line, continuously runs through a two-phase sequence 30, 52 in a characteristic curve and sawtooth shape. The first phase 30 of the sequence begins at a time 0, from which the manipulated variable value u(t) is increased linearly in a first time period 32 in two sections 36, 38. During the first time section 36, the manipulated variable value u(t) is increased with a first gradient 40 until an initial change in the controlled variable value y(t), represented by a continuous line, can be determined. In the first section 36, the rate of change of the manipulated variable value u(t) should be kept relatively low in order to be able to detect the onset of change in the controlled variable value y(t) as accurately as possible.If an initial change in the controlled variable value y(t) is detected, a transition to the second section 38 of the first time period 32 is made, in which the manipulated variable value u(t) is increased with a second gradient 42 that is greater than the first gradient 40 until saturation of the controlled variable value y(t) can be determined. The saturation of the controlled variable value y(t) can be determined by the fact that its rate of change falls below a predeterminable threshold value, so that no significant increase in the controlled variable value y(t) can be detected.

[0021] If saturation of the controlled variable value y(t) is detected, the second time period 34 of the first phase 30 is initiated. In the second time period 34 of the first phase 30, which is significantly shorter than the first time period 32, the manipulated variable value u(t) is reduced abruptly to a minimum 44, in particular approximately zero, as a result of which the controlled variable y(t) initially drops to a minimum value 50 which is greater than zero. Before the controlled variable y(t) drops with a time delay to a minimum 48, in particular approximately zero, the manipulated variable u(t) is already increased abruptly to a minimum value 46 which is greater than zero, at which the controlled variable y(t) maintains its minimum 48. The time span between the time at which the manipulated variable value u(t) reaches its minimum value 44 and the time at which the manipulated variable value u(t) reaches its minimum value 46 is approximately one second.

[0022] The fact that the controlled variable y(t) does not drop to its minimum 48 immediately after the reduction of the manipulated variable u(t), but rather with a time delay, is due to the fact that the controlled variable y(t) is regularly acquired using pulse capture, which requires low-pass filtering of the controlled variable y(t). This leads to a misinterpretation of the controlled variable y(t) in the sense that the measured value of the controlled variable y(t) is not immediately recognized as zero.

[0023] The value pair consisting of the manipulated variable u(t) and the controlled variable value y(t) of the transition from the first section 36 to the second section 38 (time 1) is stored as a start value pair, and the saturation of the controlled variable y(t) (time 2) is stored as an end value pair in the characteristic map 116. Based on this start and end value of the manipulated variable u(t), the number of state values ​​of the manipulated variable u(t) lying between these and to be stored in the characteristic map 116 is determined, the correlating controlled variable values ​​y(t) of which are to be determined in the second phase 52.

[0024] At the beginning of the second phase 52, the manipulated variable u(t) is initially increased abruptly to the manipulated variable value u(t) of time 1. The value of the manipulated variable u(t) is then increased during the first time period 54 of the second phase 52, starting from the manipulated variable value u(t) of time 1 in the direction of the manipulated variable value u(t) of time 2 with a third gradient 58 which is less than the second gradient 42 of the manipulated variable value u(t) in the second section 38 of the first time period 32 of the first phase 30, but slightly greater than the first gradient 40 of the manipulated variable value u(t) in the first section 36 of the first time period 32 of the first phase 30. The increase in the manipulated variable u(t) ends with a value which is to be stored as the penultimate manipulated variable value u(t) before the last manipulated variable value u(t) of time 2 in the characteristic map 116, so that the manipulated variable value u(t) of time 2 is not reached in the second phase 52.

[0025] During this first time period 54 of the second phase 52, several pairs of values ​​of manipulated variable u(t) and controlled variable y(t), in this case fourteen pairs of values ​​(times 3 to 16), are stored in the characteristic map 116, the manipulated variable values ​​u(t) of which lie between the start value of the manipulated variable u(t) at time 1 and the end value of the manipulated variable u(t) at time 2. The state values ​​of the manipulated variable u(t) are distributed equidistantly over the first time period 54 of the second phase 52, but can also be distributed arbitrarily over the first time period 54 of the second phase 52.

[0026] Subsequently, in the second time period 56 of the second phase 52, the value of the manipulated variable u(t) is again reduced to the minimum 44, in particular approximately zero, whereupon the controlled variable y(t) initially drops to its minimum value 50, which is greater than zero. Even before the value of the controlled variable y(t) reaches its minimum 48, in particular approximately zero, with a time delay, the manipulated variable u(t) is increased abruptly to its minimum value 46, which is greater than zero. This concludes the two phases 30, 52 of the automatic acquisition of the course of the controlled variable characteristic curve for creating the characteristic map 116.

[0027] It is conceivable that, using the characteristic map 116, the corresponding controlled variable value y(t) is interpolated for a predetermined manipulated variable value u(t) that lies between two manipulated variable values ​​u(t) stored in the characteristic map 116, or the corresponding manipulated variable value u(t) is interpolated for a predetermined controlled variable value y(t) that lies between two controlled variable values ​​y(t) stored in the characteristic map 116. The interpolated values, like the values ​​obtained by automatic characteristic curve acquisition, can be used to control or regulate the controlled variable y(t).

[0028] The control system 112 can be hydromechanically designed and / or be part of a transport device, a spreading disc, a metering shaft or a mower.

[0029] Fig. 3 shows a first embodiment and Fig. 4 a second embodiment of an electrohydraulic system 110 for carrying out the control method according to the invention. The system has a control system 112 with a pressure supply device 60 and a hydraulic consumer 62 in the form of a hydraulic motor 64, and an electroproportional actuator 114 in the form of a 2 / 2-way proportional valve 66. The pressure supply device 60 is fluidically connected on the high-pressure side via a first fluid line 68 to the hydraulic motor 64, which is connected on the output side via a second fluid line 70 to a tank T. The 2 / 2-way proportional valve 66 is provided in the first fluid line 68, the valve piston of which is electromagnetically controlled with an adjustable closing force, against the force of a compression spring, from a Fig. 3 und 4 shown first end position into a second end position. In the second end position of the valve piston, the proportional valve 66 connects its two ports to one another via a flow-free fluid path, whereas this fluid path is blocked in the first end position. The control current I of the coil of an actuating device of the proportional valve 66 represents the manipulated variable u(t). The respective coil is shown in the figures as a rectangle with an arrow running diagonally relative to it. A speed sensor 74 is provided on a motor shaft 72 of the hydraulic motor 64 for the purpose of detecting the controlled variable y(t) in the form of the speed n of the hydraulic motor 64. The speed sensor 74 can be designed as a speed-to-frequency converter, speed-to-current converter, speed-to-voltage converter and / or have a CAN bus-based signal output.Alternatively, the speed n of the hydraulic motor 64 can also be detected at another location in the associated mechanism. The speed sensor 74 is connected on the input side to a controller 18, 19 as part of the system 110, which is connected on the output side to the actuating device of the proportional valve 66. The controller 18, 19 executes the control method according to the invention. By means of this arrangement, the speed n of the hydraulic motor 64 and the volume flow of the fluid delivered by the hydraulic motor 64 can be regulated.

[0030] The first embodiment of the system according to Fig. 3 and the second embodiment of the system according to Fig. 4 differ only in the design and wiring of a pressure compensator 76, 78 used.

[0031] In Fig. 3 an inlet pressure compensator 76 is connected in the first fluid line 68 between the pressure supply device 60 and the proportional valve 66, the valve piston of which is arranged between a Fig. 3 shown first end position and a second end position. In the direction of its first end position, a compression spring and the fluid pressure in the first fluid line 68 between the proportional valve 66 and the hydraulic motor 64, which is guided to one end of the valve piston via a first control line 80, act on one end of the valve piston. In the direction of its second end position, the fluid pressure in the first fluid line 68 between the inlet pressure compensator 76 and the proportional valve 66, which is guided to the other end of the valve piston of the inlet pressure compensator 76 via a second control line 82, acts on the other end of the valve piston.In the first end position of the valve piston, the inlet pressure compensator 76 connects the pressure supply device 60 to the proportional valve 66 in a fluid-conducting manner via a flow-restriction-free fluid path, whereas this fluid path is blocked in the second end position of the valve piston.

[0032] In Fig. 4 A circulating pressure compensator 78 is provided, which is connected on the inlet side to the first fluid line 68 between the pressure supply device 60 and the proportional valve 66 and on the outlet side to the second fluid line 70. The valve piston of the circulating pressure compensator 78 is connected between a Fig. 4 shown first end position and a second end position. In the direction of the first end position, a compression spring and the fluid pressure in the first fluid line 68 between the proportional valve 66 and the hydraulic motor 64, which is guided via a third control line 84 to one end face of the valve piston of the circulation pressure compensator 78, act on one end face of the valve piston of the circulation pressure compensator 78. In the direction of the second end position, the fluid pressure in the first fluid line 68 between the pressure supply device 60 and the proportional valve 66, which is guided via a fourth control line 86 to the other end face of the valve piston of the circulation pressure compensator 78, acts on the other end face of the valve piston of the circulation pressure compensator 78.

[0033] In Fig. 5 is, depending on the current value I recorded by the actuating device of the proportional valve 66, the course of the actual controlled variable value y(t), which is shown with a dashed line, and the course of the controlled variable value measured by means of the respective speed sensor 74 y m ( t ), which is represented by a continuous line, which differ in an offset. Such an offset can be minimized by appropriate parameterization of the sequence 30, 52, i.e. the manipulated variable curve, during characteristic map acquisition and regularly results from disturbance variables d(t) acting on the controlled system 112 and / or from inertia effects of the controlled system 112 and / or from a measuring arrangement of the controlled variable y(t), for example by low-pass filtering when measuring the actual controlled variable value y(t).

[0034] Fig. 6 shows a third embodiment and Fig. 7 A fourth exemplary embodiment of the electrohydraulic system 110 according to the invention for carrying out the control method. The respective system 110 has a control system 112 with a pressure supply device 60 in the form of a hydraulic pump 88 and a hydraulic consumer 62, and an electroproportional actuator 114 in the form of a proportional valve 66. The hydraulic pump 88 is fluidly connected to the hydraulic consumer 62 on the high-pressure side via a third fluid line 90. The proportional valve 66 is connected to the third fluid line 90 on the inlet side and to a tank T on the outlet side via a fourth fluid line 92. The control current I of a coil of an actuating device of the proportional valve 66 represents the manipulated variable u(t). The respective coil is shown in the figures as a rectangle with an arrow running obliquely relative to it.A pressure sensor 94 is connected on the input side to the fourth fluid line 92 for the purpose of detecting the controlled variable y(t) in the form of a pressure value in the fourth fluid line 92. The pressure sensor 94 can be designed as a pressure-to-current converter, a pressure-to-voltage converter, and / or have a CAN bus-based signal output. On the output side, the pressure sensor 94 is connected to a controller 18 as part of the system 110, which is connected on the output side to the actuating device of the proportional valve 66. The controller 18 executes the control method according to the invention. By means of this arrangement, the supply pressure at the consumer 62 can be regulated.

[0035] The third embodiment of the system according to Fig. 6 and the fourth embodiment of the system according to Fig. 7 differ only in the design and wiring of the proportional valve 66 used.

[0036] In Fig. 6 The proportional valve 66 is designed as a pressure relief valve 96. The fluid pressure in the fourth fluid line 92 is guided via a sixth control line 100 to an end face of the valve piston of the pressure relief valve 96, and the fluid pressure in the fluid line between the pressure relief valve 96 and tank T is supplied to the actuating device of the pressure relief valve 96 via a seventh control line 102.

[0037] In Fig. 7 The proportional valve 66 is designed as a pressure control valve 98. One connection of the pressure control valve 98 is connected via an eighth control line 104 to a swivel angle adjustment 106 of the hydraulic pump 88 and is led via a ninth control line 108 to an end face of the valve piston of the pressure control valve 98.

[0038] Alternatively, the controlled variable can be the travel distance of an actuator piston and the manipulated variable can be the control current of a pump motor of a supply pump.

[0039] The coil current I of the actuating device of the respective proportional valve 66 does not correspond to the value zero without a specification, but to the minimum value 46. During the acquisition of the characteristic map 116, in the event of an abrupt drop in the control value u(t), the coil current I is reduced to its minimum 44 before it is subsequently increased again to the said minimum value 46.

Claims

1. Control method for a partially electronic system (110), such as an electrohydraulic system (110), having at least one electro-proportional actuator (114) which serves to influence at least one physical control variable (y(t)) of the system (110), comprising a control path (112), as a function of the controlled variable (u(t)) of said actuator, wherein a characteristic diagram (116) is created from correlating state values of the controlled (u(t)) and control variable (y(t)), said characteristic diagram being consulted for control processes in subsequent operation of the system (110), characterised in that to create the characteristic diagram (116), the value of the controlled variable (u(t)) is initially increased in two phases (30, 52) in a saw-toothed manner in each case, during a first time period (32, 54), until a saturation of the control variable value y(t) is determined, and is subsequently reduced during a second time period (34, 56) that is shorter than the first time period (32, 54).

2. Control method according to claim 1, characterised in that the characteristic diagram (116) comprising the state values of the controlled (u(t)) and control variable (y(t)) is two-dimensional or three-dimensional, and serves to purposely set at least a static state of the control path (112) of the system (110).

3. Control method according to either claim 1 or claim 2, characterised in that the open-loop control (18) comprising the characteristic diagram (116), said open-loop control system in each case setting a value of the control variable (y(t)) for the control path (112) as a specific pilot control, is superimposed with a closed-loop control system (19) for correcting disturbance variables.

4. Control method according to any of the preceding claims, characterised in that, to create the characteristic diagram (116), the value of the controlled variable (u(t)) is initially increased in two phases (30, 52) in a saw-toothed manner in each case, during the first time period (32, 54), and is subsequently reduced to zero during a second time period (34, 56) that is shorter than the first time period (32, 54).

5. Control method according to any of the preceding claims, characterised in that, in the first time period (32) of the first phase (30), the value of the controlled variable (u(t)) is increased linearly in each case in two portions (36, 38), and in that the value of the controlled variable (u(t)) is increased in the first time portion (36) with a first gradient (40) until an initial change in the control variable (y(t)) can be determined, whereupon in the second time portion (38) the value of the controlled variable (u(t)) is increased with a second gradient (42) that is larger than the first gradient (40), until saturation of the control variable (y(t)) can be determined.

6. Control method according to any of the preceding claims, characterised in that the value pair consisting of the controlled (u(t)) and control variable (y(t)) at the time of the transition from the first portion (36) to the second portion (38) is stored in the characteristic diagram (116) as a starting value pair, and at the time of saturation of the control variable (y(t)) is stored in said characteristic diagram (116) as the end value pair.

7. Control method according to any of the preceding claims, characterised in that, in the first time period (54) of the second phase (52), the controlled variable (u(t)) is increased with a linear third gradient (58) beginning with its starting value in the direction of its end value.

8. Control method according to any of the preceding claims, characterised in that, in the first time period (54) of the second phase (52), at least one value pair of the controlled (u(t)) and control variable (y(t)) is stored in the characteristic diagram (116), the controlled variable value (u(t)) of which is located between its start and its end value.

9. Control method according to any of the preceding claims, characterised in that the third gradient (58) of the value of the controlled variable (u(t)) in the first time period (54) of the second phase (52) is smaller than the second gradient (42) of the value of the controlled variable (u(t)) in the second portion (38) of the first time period (32) of the first phase (30).

10. Control method according to any of the preceding claims, characterised in that, by parameterisation of the value curve of the controlled variable (u(t)), a deviation of the acquired control variable (y(t)) from the actual control variable (y(t)), in particular caused by inertial effects of the control path (112) and / or by filtering of the respective control variable signal (y(t)) for the return thereof, is countered.

11. Electrohydraulic system (110) for carrying out a control method according to any of the preceding claims, characterised in that it consists at least of a pressure supply means (60), a control path (112) having a hydraulic consumer (62), and an electro-proportional actuator (114) in the form of a proportional valve (66), which can be actuated by an open-loop control (18) which obtains current state values of a control variable (y(t)) of the control path (112) via a sensor means (74, 94).

12. System according to claim 11, characterised in that the sensor means (74, 94) acquires, as the control variable (y(t)), the speed n of a hydraulic motor (64) of the control path (112) provided as the hydraulic consumer (62), or a respective pressure value of a hydraulic circuit of the control path (112).