Control device and hydraulic system equipped with the control device

Abstract

The control device is a control device that controls the movement of the valve body of the valve device in a hydraulic system. It includes: a stroke command calculation unit that calculates a stroke command for the valve body based on an input opening command; an observer that estimates the dynamic deviation of the stroke in the valve body relative to the stroke command based on the stroke command calculated by the stroke command calculation unit; and a fluid force estimation unit that estimates the fluid force acting on the valve body based on the stroke command calculated by the stroke command calculation unit and the dynamic deviation estimated by the observer; the stroke command calculation unit calculates the stroke command based on the fluid force estimated by the fluid force estimation unit in addition to the input opening command.

Description

Technical Field

[0001] The present invention relates to a control device for controlling the movement of the valve body of a valve device in a hydraulic system, and a hydraulic system having the control device. Background Technology

[0002] The hydraulic system includes a control device. This control device controls the movement of the valve body, such as the spool of a spool valve, within the hydraulic system. Such a control device is known, for example, as described in Patent Document 1. In the control device of Patent Document 1, feedback control is performed on the command current based on the spool position detected by a sensor circuit.

[0003] Existing technical documents:

[0004] Patent documents:

[0005] Patent document 1: Japanese Patent Application Publication No. 2003-167604. Summary of the Invention

[0006] The problem the invention aims to solve:

[0007] The control device in Patent Document 1 includes a sensor circuit for performing feedback control, but it is preferable to control the movement of the valve body even without detecting the valve spool position. For example, there is a method for estimating the stroke of the valve body from input values ​​such as operating commands. In this method of estimating the stroke, the stroke is mainly estimated based solely on the static balance condition of the valve spool. However, when estimating the stroke solely based on the static balance condition of the valve spool, the estimation error is relatively large. Therefore, there is a need to improve the accuracy of control related to the valve body's movement.

[0008] Therefore, the object of the present invention is to provide a control device that can improve the accuracy of control related to the movement of the valve body.

[0009] Solution methods:

[0010] The control device of the present invention controls the movement of the valve body of a valve device included in a hydraulic system, and comprises: a stroke command calculation unit that calculates a stroke command for the valve body based on an input opening command; an observer that estimates the dynamic deviation of the stroke in the valve body relative to the stroke command based on the stroke command calculated in the stroke command calculation unit; and a fluid force estimation unit that estimates the fluid force acting on the valve body based on the stroke command calculated by the stroke command calculation unit and the dynamic deviation estimated by the observer; wherein the stroke command calculation unit calculates the stroke command based on the fluid force estimated by the fluid force estimation unit in addition to the input opening command.

[0011] According to the present invention, the stroke command is calculated based on fluid forces not referenced under static equilibrium conditions, thereby enabling the calculation of a more accurate stroke command. This improves the accuracy of control related to the movement of the valve body.

[0012] The hydraulic system of the present invention comprises: a hydraulic pump for discharging working fluid supplied to an actuator; a valve device for regulating the flow rate of the working fluid supplied to the actuator; and the aforementioned control device.

[0013] According to the present invention, a hydraulic system with higher precision can be achieved in controlling the movement of the valve body.

[0014] Invention effects:

[0015] According to the present invention, the accuracy of control related to the movement of the valve body can be improved.

[0016] The above-mentioned objects, other objects, features and advantages of the present invention will become clear from the following detailed description of preferred embodiments, taking into account the accompanying drawings. Attached Figure Description

[0017] Figure 1 This is a hydraulic circuit diagram illustrating a hydraulic system according to an embodiment of the present invention;

[0018] Figure 2 yes Figure 1 A block diagram of the control devices of a hydraulic system;

[0019] Figure 3 It is shown Figure 1 A graph showing the flow rate within the valve assembly of a hydraulic system as a function of time. Detailed Implementation

[0020] Hereinafter, a hydraulic system 1 and a control device 17 according to an embodiment of the present invention will be described with reference to the accompanying drawings in the foregoing specification. Furthermore, the concept of direction used in the following description is for ease of explanation and is not intended to limit the structural orientation of the invention to the described directions. Also, the hydraulic system 1 and control device 17 described below are only one embodiment of the present invention. Therefore, the present invention is not limited to the following embodiment, and additions, deletions, or modifications may be made without departing from the spirit of the invention.

[0021] Construction machinery is equipped with hydraulic actuators and a hydraulic system to enable the movement of its various structures. For example, a hydraulic actuator may be... Figure 1 The hydraulic cylinder 2 is shown. The hydraulic cylinder 2 is installed correspondingly to various structures of the engineering machinery. The hydraulic cylinder 2 can operate the corresponding structures by extending and retracting. Further detailed, the hydraulic cylinder 2 has a rod-side port 2a and a head-side port 2b. Working fluid is supplied to each port 2a and 2b in the hydraulic cylinder 2 to extend and retract it.

[0022] The hydraulic system 1 can supply working fluid to the hydraulic cylinder 2. Moreover, the hydraulic system 1 can extend and retract the hydraulic cylinder 2 by supplying working fluid to the hydraulic cylinder 2. The hydraulic system 1 with such functions includes, for example, a hydraulic pump 11, a valve device 12, three pressure sensors 13-15, an operating device 16, and a control device 17.

[0023] The hydraulic pump 11 discharges working fluid. Further details are provided, and the hydraulic pump 11 is connected to a drive source. The drive source is an engine E or an electric motor. In this embodiment, the drive source is an engine E. The hydraulic pump 11 discharges working fluid by being driven to rotate by the engine E. Additionally, in this embodiment, the hydraulic pump 11 is a swashplate pump or a swashplate pump.

[0024] A valve device 12 is disposed between the hydraulic pump 11 and the hydraulic cylinder 2. Furthermore, the valve device 12 can control the flow direction and flow rate of the working fluid from the hydraulic pump 11 to the hydraulic cylinder 2 according to the input action command. That is, the valve device 12 can switch the flow direction of the working fluid to either of the two ports 2a and 2b of the hydraulic cylinder 2, and can also cut off the flow of working fluid to the two ports 2a and 2b. To be further detailed, the valve device 12 is an electronically controlled spool valve. That is, the valve device 12 has a directional control valve 21 and two electromagnetic proportional control valves 22L and 22R.

[0025] The directional control valve 21 is connected to the hydraulic pump 11, the rod-side port 2a and the head-side port 2b of the hydraulic cylinder 2, and the tank 3. Furthermore, the directional control valve 21 can switch the connection status of the hydraulic pump 11, the rod-side port 2a and the head-side port 2b of the hydraulic cylinder 2, and the tank 3 (i.e., connect or disconnect them respectively). This switches the flow from the hydraulic pump 11 to the hydraulic cylinder 2. By changing the flow in this way, the directional control valve 21 can cause the hydraulic cylinder 2 to extend and retract. Also, the directional control valve 21 can adjust the size of the opening when the hydraulic pump 11 is connected to the hydraulic cylinder 2, i.e., the opening degree. This allows adjustment of the flow rate of the working fluid flowing within the hydraulic cylinder 2. In other words, it allows adjustment of the extension and retraction speed of the hydraulic cylinder 2.

[0026] To elaborate further, the directional control valve 21 has a valve core 21a. The valve core 21a can change its position (i.e., stroke) to switch the connection state. Specifically, the valve core 21a can connect the hydraulic pump 11 to both the rod-side port 2a and the head-side port 2b, depending on its position. Furthermore, the valve core 21a can adjust its opening degree according to its stroke (or position). This allows for the regulation of the flow rate of the working fluid within the hydraulic cylinder 2. The valve core 21a, with this function, withstands opposing pilot pressures P1 and P2 and moves to a position corresponding to the pressure difference between the two pilot pressures P1 and P2.

[0027] As examples of electromagnetic proportional valves, the first and second electromagnetic proportional control valves 22L and 22R respectively output a first pilot pressure P1 and a second pilot pressure P2 corresponding to the input signal (current or voltage in this embodiment). The output first pilot pressure P1 and second pilot pressure P2 are introduced into the valve core 21a. Further detailed description: the first and second electromagnetic proportional control valves 22L and 22R are connected to a pilot pump (not shown). The first and second electromagnetic proportional control valves 22L and 22R adjust the working fluid discharged from the pilot pump to a pressure corresponding to the signal before outputting it to the valve core 21a.

[0028] Three pressure sensors 13-15 detect the hydraulic pressure before and after the directional control valve 21. To elaborate further, the first pressure sensor 13 is configured to correspond to the flow path connecting the directional control valve 21 and the hydraulic pump 11. The second pressure sensor 14 is configured to correspond to the flow path connecting the directional control valve 21 and the rod-side port 2a of the hydraulic cylinder 2. Furthermore, the third pressure sensor 15 is configured to correspond to the flow path connecting the directional control valve 21 and the head-side port 2b. Each pressure sensor 13-15 detects the hydraulic pressure in its corresponding flow path. Moreover, each pressure sensor 13-15 outputs the detected hydraulic pressure to the control device 17.

[0029] The operating device 16 outputs an operating command to the control device 17 to operate the hydraulic cylinder 2. The operating device 16 is, for example, an operating valve or an electric joystick. To elaborate further, the operating device 16 has an operating lever 16a as an example of an operating tool. The operating lever 16a is configured to be operable by the operator. For example, the operating lever 16a is configured to be swingable. The operating device 16 outputs an operating command corresponding to the amount of operation (in this embodiment, the amount of swing) of the operating lever 16a to the control device 17.

[0030] Control device 17 is connected to pressure sensors 13-15, two electromagnetic proportional control valves 22L and 22R, and operating device 16. Control device 17 controls the movement of valve core 21a of valve assembly 12 according to operating commands from operating device 16. More specifically, control device 17 calculates operating commands based on the detection results of pressure sensors 13-15 and operating commands from operating device 16. The operating commands are pressure commands (more specifically, actual commands described later) used to control the movement of valve core 21a of valve assembly 12. Control device 17 generates signals that are output to electromagnetic proportional control valves 22L and 22R based on the actual commands. The generated signals are output to electromagnetic proportional control valves 22L and 22R, thereby generating pilot pressures P1 and P2 corresponding to the actual commands from electromagnetic proportional control valves 22L and 22R. Thus, the movement of valve core 21a of valve assembly 12 is controlled according to the operating commands.

[0031] The control device 17 is further described in detail below. The control device 17 obtains the target flow rate value and the pressure difference across the valve device 12 to calculate the action command. The target flow rate value is the target flow rate of the working fluid flowing to the hydraulic cylinder 2. In this embodiment, the control device 17 sets the target flow rate value based on the operation command from the operating device 16. Alternatively, in this embodiment, the target flow rate value is set for calculating the action command, but it could also be a pressure target value. On the other hand, the pressure difference across the valve device 12 (i.e., the pressure difference across the directional control valve 21) is the pressure difference between the upstream and downstream sides of the valve device 12 (more specifically, the directional control valve 21) in the flow path connecting the hydraulic pump 11 and the hydraulic cylinder 2 via the valve device 12. The control device 17 obtains the pressure difference across the directional control valve 21 based on signals from three pressure sensors 13-15. Furthermore, the control device 17 includes an opening command calculation unit 31, a stroke command calculation unit 32, an observer 33, a fluid force estimation unit 34, a pressure command calculation unit 35, and a status feedback control unit 36 ​​for calculating the action command.

[0032] The opening command calculation unit 31 calculates the opening command for the directional control valve 21 based on the obtained target flow rate and the pressure difference before and after the directional control valve 21. The opening command is the degree to which the directional control valve 21 should open. In this embodiment, the opening command calculation unit 31 calculates the opening degree that allows the working fluid at the target flow rate to flow from the directional control valve 21 to the hydraulic cylinder 2.

[0033] The stroke command calculation unit 32 calculates the stroke command for the valve core 21a based on the opening command calculated by the opening command calculation unit 31. The stroke command is the amount of stroke by which the valve core 21a should move in order to change the opening degree of the directional control valve 21 to the opening degree corresponding to the opening command. To explain further, the stroke command calculation unit 32 calculates the amount of stroke by which the valve core 21a should move, taking into account the fluid force as a nonlinear element.

[0034] To elaborate further, the stroke command calculation unit 32 obtains the fluid force estimated by the fluid force estimation unit 34 (i.e., the fluid force estimation value), which will be described later. The fluid force is the load acting on the valve core 21a when the working fluid from the hydraulic pump 11 flows into the hydraulic cylinder 2 via the directional control valve 21. In this embodiment, the working fluid flowing from the directional control valve 21 onto the valve core 21a bears the fluid force in the direction of closing the opening of the directional control valve 21. The stroke command calculation unit 32 calculates the stroke command based on the fluid force estimation value and the opening command. This eliminates nonlinear elements from the mathematical model defining the movement of the valve core 21a. Furthermore, the opening command on which the stroke command calculation unit 32 is based does not necessarily have to be the command calculated by the opening command calculation unit 31. For example, the operation command from the operating device 16 can itself be an opening command.

[0035] The observer 33 estimates the state quantity of the valve core 21a based on the stroke command calculated by the stroke command calculation unit 32. In this embodiment, the state quantity estimated by the observer 33 is a vector that includes dynamic deviation and the differential value of dynamic deviation. Dynamic deviation is the amount of stroke of the valve core 21a that changes due to the load (e.g., inertial force, viscous friction, and Coulomb friction) generated by the movement of the valve core 21a when it is moved according to the stroke command.

[0036] To elaborate further, the observer 33 functions to estimate the state quantities of the valve core 21a as follows: The observer 33 calculates the inertial force and viscous resistance based on the stroke command calculated by the stroke command calculation unit 32. Furthermore, a predetermined Coulomb friction is set within the observer 33. In addition, the observer 33 has a predetermined linear equation of state. Therefore, the observer 33 estimates the state quantities of the valve core 21a based on the dynamic load, which includes the estimated inertial force, viscous resistance, and Coulomb friction, and the linear equation of state.

[0037] The fluid force estimation unit 34 calculates the fluid force based on the dynamic deviation included in the state quantity estimated by the observer 33. More specifically, the fluid force estimation unit 34 estimates the fluid force based on the estimated stroke amount of the valve core 21a. The estimated stroke amount of the valve core 21a is an estimated value of the actual stroke amount (i.e., actual stroke amount) of the valve core 21a. That is, the estimated stroke amount, as the estimated value of the stroke amount, is the value of the dynamic deviation portion of the stroke command displacement. Therefore, the estimated stroke amount of the valve core 21a is calculated by adding the stroke amount obtained by the stroke addition unit 40 to the dynamic deviation. The fluid force estimation unit 34 estimates the fluid force based on the estimated stroke amount calculated by the stroke addition unit 40. In this embodiment, an estimation formula is set in the fluid force estimation unit 34 for estimating the fluid force. The fluid force estimation unit 34 calculates the fluid force based on the aforementioned estimation formula and the estimated stroke amount.

[0038] As an example of an action command calculation unit, the pressure command calculation unit 35 calculates the pressure command based on the stroke command calculated by the stroke command calculation unit 32. The pressure command is the command value of the pilot pressure P1 and P2 that should be output from the electromagnetic proportional control valves 22L and 22R to make the valve core 21a move according to the stroke command. That is, the pressure command calculation unit 35 calculates the command value of the pilot pressure P1 and P2 (i.e., the pressure command) according to the stroke command.

[0039] The state feedback control unit 36 ​​performs state feedback on the pressure command calculated by the pressure command calculation unit 35 based on the state quantity estimated by the observer 33. Further detailed, the state feedback control unit 36 ​​includes a state feedback quantity calculation section 37, a pressure conversion section 38, and an actual command calculation section 39.

[0040] The state feedback calculation unit 37 calculates the state feedback quantity based on the state quantity estimated by the observer 33. The state feedback quantity is a value calculated for implementing state feedback control in response to pressure commands. More specifically, the state feedback quantity is the dynamic load corresponding to the dynamic deviation portion of the valve core 21a. In this embodiment, the state feedback calculation unit 37 calculates the state feedback quantity as the inner product of the state quantity estimated by the observer 33 and the gain vector.

[0041] The pressure conversion section 38 performs pressure conversion on the state feedback quantity. In this embodiment, the pressure conversion section 38 calculates the pressure based on the state feedback quantity calculated by the state feedback quantity calculation section 37. More specifically, the pressure conversion section 38 multiplies the state feedback quantity calculated by the state feedback quantity calculation section 37 by a gain K. Thus, the state feedback quantity is converted into a pressure value.

[0042] The actual command calculation unit 39 calculates the actual pressure command to be output to the electromagnetic proportional control valves 22L and 22R, i.e., the actual command, based on the pressure command calculated by the pressure command calculation unit 35 and the pressure value converted by the pressure conversion unit 38 (i.e., the converted state feedback quantity). The actual command is the command obtained by performing state feedback control on the pressure command. In this embodiment, the actual command calculation unit 39 calculates the actual command by subtracting the converted state feedback quantity from the pressure command. In this way, the state feedback control unit 36 ​​performs state feedback control on the pressure command.

[0043] Furthermore, the observer 33 also functions to estimate the state quantities of the directional control valve 21 when state feedback control based on the pressure command is implemented. Therefore, the observer 33 obtains the aforementioned state feedback quantities in addition to the stroke command. Moreover, the observer 33 uses the stroke command, state feedback quantities, and Coulomb friction as input values ​​to estimate the state quantities including dynamic deviations based on a linear state equation. Thus, the state quantities can be estimated using the observer 33, which has a model with less error relative to the hydraulic system 1. That is, the observer 33 can estimate dynamic deviations with high accuracy. Therefore, the accuracy of control related to the movement of the valve core 21a can be improved.

[0044] The control device 17, having such a function, performs the following control when the operating lever 16a of the operating device 16 is operated. Furthermore, in this embodiment, the operating lever 16a is... Figure 3 The graph, with its two-dotted line A0, shows the flow rate changing over time, operating in the form of supplying working fluid from hydraulic pump 11 to hydraulic cylinder 2. That is, control device 17 sets up based on operating commands from operating device 16, as follows: Figure 3 The target flow rate is indicated by the two-dot dashed line A0. Furthermore, the control device 17 calculates the pressure difference before and after the directional control valve 21 based on the pressure detected by the three pressure sensors 13-15.

[0045] Next, in the control device 17, the opening command calculation unit 31 calculates the opening command based on the target flow rate value and the pressure difference before and after the directional control valve 21. The stroke command calculation unit 32 calculates the stroke command based on the opening command and the fluid force estimation value. The fluid force estimation value is estimated based on the dynamic deviation included in the state quantity estimated by the observer 33. That is, the observer 33 calculates the state quantity based on the pre-calculated stroke command and the pre-estimated dynamic load (in this embodiment, the previously mentioned stroke command and dynamic load). The fluid force estimation unit 34 estimates the fluid force based on the dynamic deviation included in the state quantity. More specifically, the fluid force estimation unit 34 estimates the fluid force based on the estimated stroke amount obtained by adding the dynamic deviation and the stroke command. The fluid force estimated in this way is used for the stroke command calculated subsequently.

[0046] Furthermore, in the control device 17, the pressure command calculation unit 35 calculates the pressure command based on the stroke command. According to the pressure command, in order to open to the desired degree, the valve core 21a undergoes a dynamic deviation in stroke relative to the desired stroke amount. Therefore, according to the pressure command, the actual flow rate of the working fluid flowing in the hydraulic cylinder 2 is as follows: Figure 3 The dashed line A1 represents the change over time. That is, the actual flow rate of the working fluid within hydraulic cylinder 2 relative to the target flow rate value... Figure 3 At time t1, ΔQ1 decreases, and at... Figure 3 The pressure decreases by ΔQ2 at time t2. Therefore, in the control device 17, the state feedback control unit 36 ​​performs state feedback control on the pressure command.

[0047] That is, the state feedback calculation section 37 calculates the state feedback quantity based on the dynamic deviation. Furthermore, the pressure conversion section 38 performs a pressure conversion on the state feedback quantity. Additionally, the state feedback quantity is related to... Figure 3 The amount by which the flow rate increases by ΔQ1 at time t1 is equivalent to the amount at which the flow rate increases by ΔQ1. Figure 3 The amount by which the flow rate increases by ΔQ2 at time t2 is equivalent to the amount of time t2. Furthermore, the actual command calculation section 39 calculates the actual command based on the pressure command and the state feedback quantity to eliminate the pressure corresponding to the dynamic deviation portion from the pressure command.

[0048] Control device 17 outputs pilot pressures P1 and P2 corresponding to the calculated actual command from electromagnetic proportional control valves 22L and 22R. This causes the valve core 21a of directional control valve 21 to move to a position corresponding to the operating amount of operating lever 16a. In other words, control device 17 controls the movement of valve core 21a. This allows the flow rate of the working fluid actually flowing in hydraulic cylinder 2 to approach the target flow rate value (see...). Figure 3 (The solid line A2 in the chart).

[0049] In the control device 17 of the hydraulic system 1 configured in this way, the stroke command calculation unit 32 calculates the stroke command based on the opening command and the estimated fluid force value. That is, the stroke command is calculated based on the fluid force that is not referenced when calculating the stroke command under static equilibrium conditions. Therefore, the stroke command can be calculated with higher accuracy, and the directional control valve 21 can be opened with an opening degree corresponding to the opening command. As a result, the accuracy of control related to the movement of the valve core 21a can be improved.

[0050] Furthermore, the control device 17 of the hydraulic system 1 considers the estimated fluid force value when calculating the stroke command, and eliminates nonlinear elements from the mathematical model specifying the movement of the valve core 21a. Therefore, the control device 17 can perform state feedback on the pressure command based on the dynamic deviation calculated from the stroke command. By performing state feedback in this way, the delay in the stroke of the valve core 21a during over-response can be suppressed. That is, the delay in the stroke caused by the dynamic deviation of the valve core 21a during over-response can be suppressed. Therefore, the accuracy of control related to the movement of the valve core 21a can be further improved.

[0051] Furthermore, the control device 17 of the hydraulic system 1 performs state feedback control based on the dynamic deviation of the valve core 21a, thus improving the accuracy of sensorless state feedback control compared to state feedback control based on stroke amount. That is, by using a dynamic deviation whose absolute value is smaller than the stroke amount, the influence of modeling errors on state feedback can be reduced. Therefore, more robust control can be achieved through state feedback control.

[0052] Furthermore, in the control device 17, the observer 33 estimates the dynamic deviation based on the previous value of the dynamic deviation (more specifically, the state feedback quantity), in addition to the stroke command. Therefore, the observer 33 can incorporate a model of the control system with state feedback control, allowing the hydraulic system 1 to be modeled with higher accuracy. This enables the estimation of dynamic deviation with higher accuracy. Consequently, the accuracy of control related to the movement of the valve core 21a can be improved. Moreover, since the control device 17 of the hydraulic system 1 estimates the dynamic deviation based on the inertial force, viscous resistance, and Coulomb friction acting on the valve core 21a, the accuracy of control related to the movement of the valve core 21a can be improved.

[0053] <Other Implementation Methods>

[0054] The hydraulic system 1 of this embodiment is suitable for construction machinery, but it can also be applied to industrial vehicles such as forklifts or industrial machinery such as stamping machines. Furthermore, in the hydraulic system 1 of this embodiment, only one directional control valve 21 is connected relative to the hydraulic pump 11, but multiple directional control valves 21 can be connected in parallel or series. Also, the hydraulic actuator connected to the directional control valve 21 is not limited to a hydraulic cylinder 2, but can also be a hydraulic motor.

[0055] Furthermore, in the hydraulic system 1 of this embodiment, the hydraulic actuator is exemplified by a hydraulic cylinder 2, but the hydraulic actuator can also be a hydraulic motor. Also, the type of hydraulic cylinder 2 is not limited to a single-rod multi-acting cylinder; double-rod cylinders and single-acting cylinders are also acceptable. Furthermore, the structure included in the valve device 12 is not limited to a directional control valve 21; any structure that allows adjustment of the opening size via the valve body is acceptable. The action command is not necessarily limited to a pressure command; a current command is also acceptable.

[0056] Furthermore, in the hydraulic system 1 of this embodiment, the valve core 21a of the directional control valve 21 moves according to the pilot pressure from the electromagnetic proportional control valves 22L and 22R. However, the driving method of the valve core 21a of the directional control valve 21 is not necessarily limited to this method. For example, the valve core 21a of the directional control valve 21 may also be driven by an electric motor via a direct-acting mechanism. In this case, the action command is a drive signal to drive the electric motor.

[0057] From the foregoing description, numerous modifications and other embodiments of the present invention will become apparent to those skilled in the art. Therefore, the foregoing description should be interpreted as illustrative only, provided for the purpose of teaching those skilled in the art the optimal mode for carrying out the invention. Substantial changes to its specific structure and / or function may be made without departing from the spirit of the invention.

[0058] Symbol explanation:

[0059] 1. Hydraulic system;

[0060] 11. Hydraulic pump;

[0061] 12. Valve assembly;

[0062] 17. Control device;

[0063] 21. Directional control valve (spool valve);

[0064] 21a Valve core (valve body);

[0065] 22L First electromagnetic proportional control valve;

[0066] 22R Second electromagnetic proportional control valve;

[0067] 31. Opening instruction calculation unit;

[0068] 32. Travel instruction calculation unit;

[0069] 33. Observer;

[0070] 34. Fluid dynamics estimation section;

[0071] 35. Pressure command calculation unit (motion command calculation unit);

[0072] 36. Status Feedback Control Department

Claims

1. A control device for controlling the movement of the valve body of a valve assembly in a hydraulic system. It has a stroke command calculation unit that calculates the stroke command for the valve body based on the input opening command; An observer that estimates the dynamic deviation of the stroke in the valve body relative to the stroke command based on the stroke command calculated by the stroke command calculation unit; and A fluid force estimation unit estimates the fluid force acting on the valve body based on the stroke command calculated by the stroke command calculation unit and the dynamic deviation estimated by the observer. In addition to the input opening command, the stroke command calculation unit also calculates the stroke command based on the fluid force estimated by the fluid force estimation unit.

2. The control device according to claim 1, characterized in that, It also has an action command calculation unit that calculates action commands to control the movement of the valve body based on the stroke command calculation unit; A state feedback control unit that provides feedback on the execution status of the action command calculated by the action command calculation unit based on the dynamic deviation calculated by the observer.

3. The control device according to claim 2, characterized in that, In addition to the travel command, the observer also estimates the dynamic deviation based on the previous value of the dynamic deviation estimated by the observer.

4. The control device according to any one of claims 1 to 3, characterized in that, The observer calculates the inertial force and viscous resistance acting on the valve body based on the stroke command, and estimates the dynamic deviation of the stroke based on the inertial force, viscous resistance and predetermined Coulomb friction acting on the valve body.

5. A hydraulic system comprising: A hydraulic pump that discharges working fluid supplied to the actuator; A valve device for regulating the flow rate of the working fluid supplied to the actuator; and The control device as described in any one of claims 1 to 4.

6. The hydraulic system according to claim 5, characterized in that, The valve device includes at least one electromagnetic proportional valve and a spool valve; The slide valve has a valve core that serves as the valve body; The valve core travels according to the pilot pressure acting on it; The electromagnetic proportional valve outputs a pilot pressure that acts on the valve core; The control device calculates a pressure command as an action instruction, and outputs a pilot pressure corresponding to the calculated pressure command from the electromagnetic proportional valve to control the movement of the valve core.

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