Control device and control method

Abstract

To provide a control device and a control method capable of performing force control or position control with high control performance with a simple configuration in a machine driven by a hydraulic actuator.SOLUTION: The force control device 10 includes a control unit 101 that determines an operation amount of the hydraulic actuator 31 that drives the control target 30. The control unit 101 includes a reference speed calculation unit 1011 that calculates a reference speed, which is a speed to be achieved at the next time step of the control target 30, based on a measurement value of the generated force of the hydraulic actuator 31 or a force measurement value, which is a measurement value of the force of contact between the control target 30 and the external environment as an object, and the target generated force of the hydraulic actuator 31, and an operation amount calculation unit 1012 that calculates an operation amount of the hydraulic actuator 31 based on the quasi-static characteristics of the hydraulic actuator 31, the reference speed, and the force measurement value.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a control device and a control method for performing force control or position control on a control object driven by a hydraulic actuator. [Background technology]

[0002] Conventionally, control devices and control methods have been developed for machines driven by hydraulic actuators, etc. However, because the response characteristics of hydraulic actuators are highly nonlinear, it is difficult to control the force acting on the machine (the controlled object) and the positioning control of the machine (position control) using simple control laws.

[0003] In Patent Document 1, a prediction equation that predicts the position and velocity of the controlled object at the next time step and an equation that represents a sliding mode control law are solved as simultaneous equations based on prior information about the dynamic characteristics of the controlled object, and a valve opening command to a hydraulic actuator, which is a manipulated variable, is calculated. However, with the control method of Patent Document 1, if the prior information about the dynamic characteristics of the controlled object is inaccurate or if there is a time delay in the response of the hydraulic actuator, the accuracy of the prediction equation cannot be ensured, and there is a risk that desired control characteristics cannot be obtained.

[0004] Patent Document 2 proposes a position control law in which the dynamic characteristic model according to Patent Document 1 is replaced with a PID controller, and a force control law that incorporates the position control law. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-121717 [Patent Document 2] Japanese Patent Publication No. 2024-31851 Summary of the Invention [Problem to be solved by the invention]

[0006] The control method of Patent Document 2 does not depend on a dynamic characteristic model of the controlled object, but it is necessary to adjust the parameters of both the sliding mode control and the PID control to suit the controlled object. Also, since the force control law according to Patent Document 2 has a structure that includes a position control law, it is necessary to adjust the parameters added for force control in addition to adjusting the parameters of the position control law. Since the appropriate values ​​of the parameters added for force control depend not only on the controlled object but also on the values ​​of the position control parameters, there is a problem in that it is difficult to adjust the parameters.

[0007] The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide a control device and a control method that are simple in configuration but can perform force control or position control with high control performance for a machine driven by a hydraulic actuator. [Means for solving the problem]

[0008] In order to achieve the above object, a control device according to a first aspect of the present invention comprises: a control unit that determines an operation amount of a hydraulic actuator that drives a controlled object; The control unit a reference speed calculation unit that calculates a reference speed, which is a speed to be achieved at a next time step of the controlled object, based on a measurement value of the generated force of the hydraulic actuator or a force measurement value that is a measurement value of a force at which the controlled object comes into contact with an external environment that is an object, and a target generated force of the hydraulic actuator; and an operation amount calculation unit that calculates an operation amount of the hydraulic actuator based on the quasi-static characteristic of the hydraulic actuator, the reference velocity, and the force measurement value.

[0009] The reference speed is: is a velocity at the next time point calculated by simulating the motion of a virtual object having predetermined dynamic characteristics when the target generated force and the force measurement value are applied to the virtual object. This may also be the case.

[0010] Further, the control unit a reference speed update unit that updates the reference speed using a plant energy amount that is an energy amount of the controlled object and the external environment and an energy amount of the hydraulic actuator when the hydraulic actuator has a dead time that is a time delay in operation with respect to an input of an operation amount, This may also be the case.

[0011] Further, the reference speed update unit calculating a target energy amount based on the target generated force; calculating an estimated plant energy amount that is an estimate of the plant energy amount after a dead time has elapsed; estimating a work of the hydraulic actuator when the manipulated variable is calculated using the reference speed before updating; updating the reference speed so that the reference speed is within a predetermined range when the estimated plant energy amount at the next time step deviates from the target energy amount or when the estimated plant energy amount at the next time step exceeds the target energy amount due to work by the hydraulic actuator; This may also be the case.

[0012] Moreover, in a control method according to a second aspect of the present invention, calculating a reference speed, which is a speed to be achieved at a next time step of the controlled object, based on a measured value of a generated force of a hydraulic actuator that drives the controlled object or a force measurement value that is a measured value of a force at which the controlled object comes into contact with an external environment that is an object, and a target generated force of the hydraulic actuator; The manipulated variable of the hydraulic actuator is calculated based on the quasi-static characteristic of the hydraulic actuator, the reference velocity, and the force measurement value.

[0013] Furthermore, a control device according to a third aspect of the present invention comprises: a control unit that determines an operation amount of a hydraulic actuator that drives a controlled object; The control unit a reference speed calculation unit that calculates a reference speed, which is a speed that should be achieved at a next time step of the controlled object, based on a target position and a measured position of the controlled object; and an operation amount calculation unit that calculates an operation amount of the hydraulic actuator based on the quasi-static characteristic of the hydraulic actuator, the reference velocity, and a force measurement value that is a measurement value of the force generated by the hydraulic actuator.

[0014] The reference speed is: proportional to the difference between the target position and the measured position and the target velocity of the controlled object; This may also be the case.

[0015] In addition, the control unit a reference speed update unit that updates the reference speed using an amount of energy of the hydraulic actuator and an amount of energy of the controlled object when the hydraulic actuator has a dead time that is a time delay in operation with respect to an operation amount input, This may also be the case.

[0016] Further, the reference speed update unit calculating a target energy amount based on the reference speed; calculating an estimated controlled object energy amount, which is an estimated value of the controlled object energy amount after the dead time has elapsed; estimating a work of the hydraulic actuator when the manipulated variable is calculated using the reference speed before updating; updating the reference speed so that the reference speed is within a predetermined range when the estimated controlled energy amount at the next time step deviates from the target energy amount or when the estimated controlled energy amount at the next time step exceeds the target energy amount due to work by the hydraulic actuator; This may also be the case.

[0017] Moreover, in a control method according to a fourth aspect of the present invention, calculating a reference speed, which is a speed to be achieved at a next time step of a controlled object driven by a hydraulic actuator, based on a target position and a measured position of the controlled object; The operation amount of the hydraulic actuator is calculated based on the quasi-static characteristic of the hydraulic actuator, the reference velocity, and a force measurement value that is a measurement value of the force generated by the hydraulic actuator. [Effects of the Invention]

[0018] According to the control device and control method of the present invention, it is possible to perform force control or position control with high control performance in a machine driven by a hydraulic actuator, despite having a simple configuration. [Brief explanation of the drawings]

[0019] [Figure 1] 1A and 1B are diagrams showing the configuration of a control system including a control device according to the present invention, where FIG. 1A is a diagram for force control and FIG. 1B is a diagram for position control. [Figure 2] 1 is a diagram illustrating a configuration of a hydraulic actuator according to an embodiment. [Figure 3] 1A is a functional block diagram of a force control device according to a first embodiment, and FIG. 1B is a functional block diagram of a force control device according to a second embodiment. [Figure 4] 1A is a functional block diagram of a position control device according to a third embodiment, and FIG. 1B is a functional block diagram of a position control device according to a fourth embodiment. [Figure 5] FIG. 1A is a diagram of a hydraulic testing machine according to an embodiment, and FIG. 1B is a block diagram of the hydraulic testing machine. [Figure 6] 5A and 5B are diagrams showing the results of force control according to the first embodiment, in which (A) is a diagram when a step-shaped target generated force is used, and (B) is a diagram when a sine wave-shaped target generated force is used. [Figure 7] 10A and 10B are diagrams showing the results of force control when there is dead time in the first embodiment, where (A) is a diagram showing the case where there is a step-like target generated force and no dead time countermeasure is taken, and (B) is a diagram showing the case where there is a step-like target generated force and a dead time countermeasure is taken. [Figure 8]1A and 1B are diagrams showing the results of force control when there is dead time in the first embodiment, where (A) is a diagram showing the case where there is no dead time countermeasure with a sine wave-shaped target generated force, and (B) is a diagram showing the case where there is a dead time countermeasure with a sine wave-shaped target generated force. [Figure 9] 10A and 10B are diagrams showing the results of position control according to Example 2, where (A) is a diagram when a step-shaped target generated force is used, and (B) is a diagram when a sine wave-shaped target generated force is used. [Figure 10] 10A and 10B are diagrams showing the results of position control when the dead time is set to 0.1 seconds in Example 2, where (A) is a diagram when no dead time countermeasure is taken, and (B) is a diagram when a dead time countermeasure is taken. [Figure 11] 10A and 10B are diagrams showing the results of position control when the dead time is set to 0.3 seconds in Example 2, where (A) is a diagram when no dead time countermeasure is taken, and (B) is a diagram when a dead time countermeasure is taken. DETAILED DESCRIPTION OF THE INVENTION

[0020] (Embodiment 1) Hereinafter, a control device and a control method according to the present invention will be described with reference to the drawings. First, a control device (hereinafter referred to as a force control device 10) that performs force control according to an embodiment of the present invention and a control method using the force control device 10 will be described. As shown in FIG. 1(A), the force control device 10 according to this embodiment includes a virtual object (proxy) represented by a mass damper system and a quasistatic actuator model. The force control device 10 applies a target generated force f to the virtual object. d Assume that the force generated by the hydraulic actuator (actuator force f) measured as follows is acting on the virtual object, and the velocity v x The force control device 10 also calculates the quasi-static model, the virtual object velocity v x The control input u is calculated based on the actuator force f, which is a force measurement value.

[0021] (Control Algorithm) First, the control law of the force control device 10 according to this embodiment will be described, that is, the control algorithm for determining the control input u, which is the manipulated variable of the hydraulic actuator 31, when the controlled object 30 is a machine driven by the hydraulic actuator 31, which is a hydraulic actuator, and the actuator force f, which is affected by contact between the controlled object 30 and the external environment 40, which is an object, is controlled.

[0022] A specific configuration of hydraulic actuator 31 according to this embodiment is as shown in Fig. 2. As shown in Fig. 2, hydraulic actuator 31 includes a hydraulic pump 311a that supplies hydraulic pressure, a pump relief valve 311b, a bleed valve 311c, a pump check valve 311d, a main control valve 312 that controls the hydraulic pressure, a rod-side relief valve 313a, a rod-side check valve 313b, a head-side relief valve 314a, a head-side check valve 314b, and a cylinder 315 that operates by hydraulic control. Hydraulic actuator 31 also includes a regeneration circuit 316, which includes a check valve 316a and a flow control valve 316b.

[0023] The characteristics of the hydraulic actuator 31 are expressed by the following equation (1).

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[0024] The control object of the formula (1) is the actuator force f, the disturbance g, and the reaction force (contact force) f from the external environment 40. eThe set-valued function Γ is a quasi-static model of the hydraulic actuator, and is given as a set-valued function from the current velocity v and the control input u, which is a valve opening command, to the actuator force f. The specific form of the set-valued function Γ, which is a quasi-static model of the hydraulic actuator 31 operated in a state in which the regeneration circuit 316 is removed from the hydraulic circuit of the hydraulic actuator 31 in Figure 2, i.e., in a state in which the regeneration circuit 316 is always closed, is shown in equation (19) in known document 1 (R. Kikuuwe, et al., “A nonsmooth quasi-static modeling approach for hydraulic actuators,” J. Dyn. Sys., Meas., Control, vol. 143, no. 12, p. 121002, 2021) and equation (24) in known document 2 (Y. Yamamoto, et al., “A sliding-mode set-point position controller for hydraulic excavators”, IEEE Access, vol. 9, pp. 153735-153749, 2021).

[0025] The control input u∈[-1, 1], which is the second argument of the function Γ, is a variable that indicates the opening degree of the four main control valves 312 shown in Figure 2. The control input u and the opening degree u of the main control valve 312 * ∈[0,1](*∈{ph,pr,th,tr}) has the following relationship.

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[0026] Here, an inverse function Θ and a single-valued function Θs for the second argument of the function Γ shown in the following equation (3) are introduced.

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[0027] In this embodiment, the force control law for the hydraulic actuator 31 shown in the following equation (4) is used.

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[0028] Equation (4a) represents the dynamic characteristics of the virtual object, and M x is the mass of the virtual object, B x is the viscosity of the virtual object, v x is the velocity of the virtual object. Equation (4b) expresses the virtual object velocity v x Based on the measured actuator force f, the control input u∈[-1,1] is calculated using a set-valued function Θ that represents the quasi-static actuator model. Equation (4b) expresses the virtual object velocity v x This can also be interpreted as a velocity feedforward controller where the desired velocity is

[0029] The actuator force f, which is the force measurement value in the control law of Equation (4), is not limited to the force generated by the hydraulic actuator 31 measured by a force sensor, but may be an estimated value. e If is measurable, the contact force f e may be used as the actuator force f.

[0030] By discretizing the control law in equation (4) and replacing the set-valued function Θ with the single-valued function Θs defined in equation (3), we obtain the following control algorithm for calculating the control input u from the actuator force f.

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[0031] A functional block diagram of the force control device 10 that executes control is shown in Figure 3(A). As shown in Figure 3(A), the force control device 10 includes a control unit 101 that executes the control algorithm of the above equation (5), a memory unit 102 that stores programs, data, etc. related to the control algorithm, an input unit 103 that inputs parameters, etc. related to the control, such as a target generated force. The control unit 101 also includes a reference speed calculation unit 1011 and an operation amount calculation unit 1012.

[0032] The reference speed calculation unit 1011 calculates the target generated force f of the hydraulic actuator as shown in equation (5a). d and the actuator force f, the reference velocity v, which is the velocity that the controlled object should achieve at the next time step. x More specifically, the reference speed calculation unit 1011 calculates the target generated force f d The motion of a virtual object with predetermined dynamic characteristics is simulated by applying the actuator force f, which is a force measurement value, to calculate the velocity at the next time point, and the reference velocity v x In addition, the operation amount calculation unit 1012 calculates the quasi-static characteristics of the hydraulic actuator, the reference velocity v x and the actuator force f, the control input u of the hydraulic actuator is calculated.

[0033] As described above, the control device and control method according to this embodiment can control the force of a hydraulic actuator with a simple configuration that requires few parameters to be adjusted by trial and error in accordance with the controlled object. Specifically, the control device and control method according to this embodiment require few parameters to be adjusted by trial and error in accordance with the controlled object, such as the viscosity B x and mass M x The five adjustment parameters in the force control described in Patent Document 2 (PID gains K and L, time constant H, viscosity B of the virtual object) v and mass M v ) is smaller than the viscosity B of the virtual object, which is an adjustment parameter according to this embodiment. x and mass M xcorrespond to the viscosity coefficient and mass of the virtual object expressed by equation (4), respectively, so it is easy to intuitively predict the effect of each parameter on the control performance, and adjustment is simple.

[0034] (Embodiment 2) The hydraulic actuator 31 generally has a time delay between the control input u and the operation of the rod. The control device and control method according to this embodiment differ from the force control algorithm (equation (5)) of the first embodiment in that a dead time countermeasure based on the amount of energy is applied. The dead time countermeasure according to this embodiment will be described below.

[0035] The power output of the hydraulic actuator 31, which receives the control input u, on the controlled object. · E a Assuming that is determined by the product of the velocity and force input to the function Θ when the control input u is calculated, it can be expressed as the following equation (6).

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[0036] Based on equation (6), the length T d The amount of energy of the hydraulic actuator 31 that appears to be delayed in reaching the controlled object due to the dead time element or stored in the dead time element. ― E a is expressed as the following equation (7).

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[0037] Next, the energy amount E (hereinafter also referred to as plant energy amount E) possessed by the external environment 40 and the controlled object in contact with the hydraulic actuator 31 is calculated. d Calculate the target energy amount E d is the amount of energy related to the state of the controlled object that is desired to be achieved, and in this embodiment, the target generated force f dThe external environment 40 that comes into contact with the controlled object is calculated based on the stiffness coefficient K r Assuming that the linear spring is M and the mass of the controlled object is M, the plant energy amount E and the target energy amount E d is expressed as the following equation (8).

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[0038] Amount of energy stored in dead time elements ― E a , plant energy amount E and target energy amount E d From this, the energy margin ΔE is calculated as shown in the following equation (9).

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[0039] In the dead time countermeasure according to this embodiment, the energy margin ΔE and the amount of energy ^E newly input to the controlled object from the hydraulic actuator 31 at the current time step are a If the control system is deemed to be unstable, the velocity of the virtual object is corrected. Specifically, as shown in the following equation (10), the velocity of the virtual object v x Fix.

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[0040] Here, the sign function sgn and the saturation function sat are defined as in the following equations (11) and (12): m >0,v p >0 are parameters that represent the lower and upper limits of velocity saturation after correction. m ,v p The smaller the value of is, the more the vibration of the actuator force f can be suppressed, but the quick response will be reduced. m ,v pIt is preferable that v be adjusted to an appropriate value based on preliminary experiment data, past performance data, etc. More specifically, in order to avoid the risk of destabilizing the controlled object, v m ,v p Both should be set to a sufficiently small value and then gradually increased until the response speed meets the task objectives, at which point an appropriate value can be set.

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[0041] When the above-described dead time countermeasure is incorporated into the algorithm (5) for calculating the control input of the force control law, the algorithm is expressed as the following equation (13).

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[0042] where ^E a,k is the estimated amount of energy newly input to the plant at the current time step, and v x,k , ^f k , j are as shown in the following equation (14): The function floor is a function that rounds down the decimal point of the input value.

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[0043] A functional block diagram of a force control device 10' according to this embodiment is shown in Figure 3(B). As shown in Figure 3(B), in addition to the configuration of the force control device 10 according to embodiment 1, the force control device 10' according to this embodiment includes a reference speed update unit 1013 that updates the reference speed using the energy amounts of the controlled object, the hydraulic actuator, and the external environment.

[0044] As shown in the algorithm of the above equations (13b) to (13g), when the hydraulic actuator has a time delay in its operation relative to the input of the manipulated variable, the reference speed update unit 1013 updates the reference speed v x Specifically, the reference velocity update unit 1013 updates the target generated force f d Based on the target energy amount E d Calculate (equation (13d)) and calculate the dead time T d Estimated plant energy amount after elapsed time E+ΔE a The energy margin ΔE is calculated using equation (13e) and the reference speed before updating v x The work of the hydraulic actuator when the manipulated variable u is calculated using a (Equation (13f)). Then, when the estimated plant energy amount at the next time step is getting farther from the target energy amount, or when the estimated plant energy amount at the next time step exceeds the target energy amount, the reference speed update unit 1013 updates the reference speed v x More specifically, the estimated work of the hydraulic actuator, ^E a acts on the controlled object, increasing the magnitude of the energy margin ΔE (the first condition in equation (13g) is true), or the estimated work ^E a When the magnitude of the reference velocity v exceeds the magnitude of the energy margin ΔE (the second condition in equation (13g) is true), the reference velocity v is set to be within a predetermined range. x Update (equation (13g)).

[0045] Furthermore, as shown in equation (13h), the operation amount calculation unit 1012 calculates the quasi-static characteristics of the hydraulic actuator, the reference velocity v after the update process, x The control input u of the hydraulic actuator is calculated based on the actuator force f, which is a force measurement value.

[0046] As described above, in the control device and control method according to the present embodiment, the reference velocity v , which is the velocity of the virtual object, is calculated based on the total amount of mechanical energy stored in the hydraulic actuator 31, the controlled object, and the dead time element. xIn other words, since a dead time countermeasure is applied based on the energy balance of the control system, it is possible to improve the control performance in response to the dead time associated with the hydraulic actuator while suppressing the control system from becoming unstable.

[0047] (Embodiment 3) Next, a control device (hereinafter referred to as position control device 11) for performing position control according to an embodiment of the present invention and a control method by the position control device 11 will be described. As shown in FIG. 1(B), the position control device 11 according to this embodiment controls the velocity v of a virtual object. x Instead, the current position p and the target position p d The reference velocity v calculated from r is input to the quasi-static model, which is different from the force control device 10 according to the first embodiment.

[0048] The position control law according to this embodiment is the position control law for the hydraulic actuator 31 expressed by the following equation (15).

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[0049] The above equation (15a) is the reference velocity v r , the target position p d and the measurement position p. Here, H is the convergence time constant of the reference velocity. Furthermore, equation (15b) expresses that the reference velocity v r Based on the measured actuator force f, the control input u∈[-1,1] is calculated using a set-valued function Θ that represents the quasi-static actuator model.

[0050] By discretizing the control law in equation (15) and replacing the set-valued function Θ with the single-valued function Θs defined in equation (3), we obtain the following control algorithm that calculates the control input u from the actuator force f and position p.

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[0051] A functional block diagram of the position control device 11 that executes control is shown in Figure 4(A). As shown in Figure 4(A), the position control device 11 includes a control unit 111 that executes the control algorithm of the above equation (16). Like the force control device 10, the position control device 11 also includes a storage unit 102 that stores a control program, data, etc., an input unit 103 that inputs parameters related to control, etc.

[0052] The reference speed calculation unit 1111 calculates the target position p of the controlled object as shown in equations (16a) to (16c). d and the position p measured by the position sensor 33, a reference speed v which is the speed to be achieved at the next time step of the controlled object is calculated. r More specifically, the reference velocity v r is the target position p d and the difference between the measured position p and the target velocity v of the controlled object d is proportional to.

[0053] Furthermore, the operation amount calculation unit 1112 calculates the quasi-static characteristics of the hydraulic actuator, the reference velocity v r The control input u of the hydraulic actuator is calculated based on the actuator force f, which is a force measurement value.

[0054] As explained above, the control device and control method according to this embodiment can perform position control of a hydraulic actuator with a simple configuration that requires few parameters to be adjusted by trial and error in accordance with the controlled object. Specifically, in the control device and control method according to this embodiment, the parameter that requires trial and error adjustment in accordance with the controlled object is only one, the convergence time constant H of the reference speed, which is fewer than the four adjustment parameters (PID gains K, L, D, and time constant H) in the position control according to Patent Document 2. Furthermore, the time constant H, which is an adjustment parameter according to this embodiment, is calculated by multiplying the target position p of the position p by the PID gain K, L, D, as shown in equation (15a). dSince this corresponds to the time constant for convergence to the target value, it is possible to set a small value to shorten the convergence time, and a large value to lengthen it. This can be adjusted intuitively and is easy to adjust.

[0055] (Fourth embodiment) The control device and control method according to this embodiment differ from the position control algorithm (equation (16)) of the third embodiment in that a dead time countermeasure based on the amount of energy is applied. The dead time countermeasure according to this embodiment will be described below.

[0056] When applying the dead time countermeasure to the position control device having the control law of equation (15), the velocity v of the virtual object in equations (6) to (10) x Refer to the velocity v r In addition, unlike the force control according to the first and second embodiments, there is no external environment that comes into contact with the controlled object, so the energy amount E of the controlled object and the target energy amount E in equation (8) are replaced by d is expressed as the following equation (17).

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[0057] When the above-described dead time countermeasure is incorporated into the algorithm of equation (16) for calculating the control input of the position control law, the algorithm is expressed as shown in the following equation (18).

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[0058] where ^E a,k is the estimated amount of energy newly input to the plant at the current time step, and v r,k , ^f k , j are as shown in the following equation (19): The function floor is a function that rounds down the decimal point of the input value.

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[0059] A functional block diagram of a position control device 11' according to this embodiment is shown in Fig. 4(B). As shown in Fig. 4(B), the position control device 11' according to this embodiment includes, in addition to the configuration of the position control device 11 according to the third embodiment, a reference speed update unit 1113 that updates the reference speed using the energy amounts of the controlled object and the hydraulic actuator.

[0060] As shown in the algorithm of the above equations (18d) to (18i), when the hydraulic actuator has a time delay in its operation relative to the input of the manipulated variable, the reference speed update unit 1113 updates the reference speed v r Specifically, the reference speed update unit 1113 updates the reference speed v r Based on the target energy amount E d Calculate (equation (18f)) and calculate the dead time T d Estimated plant energy amount after elapsed time E+ΔE a The energy margin ΔE is calculated using equation (18g), and the reference speed before updating v r The work of the hydraulic actuator when the manipulated variable u is calculated using a (Equation (18h)). Then, when the estimated controlled energy amount of the next time step is getting farther from the target energy amount, or when the estimated controlled energy amount of the next time step exceeds the target energy amount, the reference speed update unit 1113 updates the reference speed v r More specifically, the estimated work of the hydraulic actuator, ^E a acts on the controlled object, increasing the magnitude of the energy margin ΔE (the first condition in equation (18i) is true), or when the estimated work ^E a When the magnitude of the reference velocity v exceeds the magnitude of the energy margin ΔE (the second condition of equation (18i) is true), the reference velocity v is set to be within a predetermined range. r Update (equation (18i)).

[0061] Furthermore, as shown in equation (18j), the operation amount calculation unit 1112 calculates the quasi-static characteristics of the hydraulic actuator, the reference velocity v after the update process, r The control input u of the hydraulic actuator is calculated based on the actuator force f, which is a force measurement value.

[0062] As described above, in the control device and control method according to the present embodiment, the reference speed v is calculated based on the total amount of mechanical energy stored in the hydraulic actuator 31, the controlled object, and the dead time element. r In other words, since a dead time countermeasure is applied based on the energy balance of the control system, it is possible to improve the control performance in response to the dead time associated with the hydraulic actuator while suppressing the control system from becoming unstable.

[0063] Example 1 5(A) and 5(B), experiments were conducted to confirm the control performance of the force control laws according to the first and second embodiments. The hydraulic testing machine includes a force control device 10, which is a computer device, and a control target 30 including a hydraulic actuator. The control target 30 includes a hydraulic cylinder, which is a hydraulic actuator, hydraulic pressure sensors for measuring the pressures inside the rod-side and head-side chambers of the hydraulic cylinder, a load cell for measuring the contact force between the hydraulic cylinder and the external environment 40, and a linear encoder for measuring the rod length.

[0064] The force control device 10 commands the flow control valve to a voltage value corresponding to the control input u. This control period was set to T = 0.01 s. The pump flow rate of the hydraulic testing machine was set to a constant value, and excess oil during the operation of the hydraulic cylinder was returned to the tank by a relief valve or flow control valve close to the pump. The dead time at the start of operation of the hydraulic testing machine in this example was measured in a preliminary experiment and was between 0.01 s and 0.03 s.

[0065] Under the above conditions, contact force control was performed using the force control laws according to the first and second embodiments. The parameters related to the control laws were M x =10kg, B x =400N·s / m, M=6kg, K r=5×10 5 N / m. The upper and lower limits of velocity saturation after correction for dead time countermeasures are [-v m ,v p ]=[-1×10 -4 m / s, 1×10 -4 The external environment 40, which is the contact object, is a rubber plate with a Shore hardness of A50. The nominal values ​​of the testing machine were used as parameters for the quasi-static actuator model.

[0066] The results of the force control experiments are shown in Figures 6(A) and (B). Figure 6(A) shows the experimental results when the target generated force is changed in a step-like manner, and Figure 6(B) shows the experimental results when the target generated force is changed in a sine wave manner. In both cases, the hydraulic cylinder and the contact object are not in contact in the initial state, but come into contact around t = 5s. As shown in Figures 6(A) and (B), it can be seen that for both target generated forces, the actuator force follows the target generated force without any large error.

[0067] Figure 7(A) and (B) show the software dead time T d = 0.3 s. Figures 7(A) and (B) show the results of an experiment to track a step-like target generated force, with Figure 7(A) showing the result without dead time countermeasures and Figure 7(B) showing the result with dead time countermeasures. In the result of Figure 7(A), where dead time countermeasures were not taken, it can be seen that the actuator force was oscillating and the control system was unstable. In addition, the rod length p was also oscillating greatly, which was dangerous, so the experiment was stopped around t = 40 s. As shown in Figure 7(B), when dead time countermeasures were taken, it can be seen that the actuator force was tracking the target generated force and stable control was achieved.

[0068] Figure 8(A) and (B) show the software dead time T dThese are the results of an experiment to track the sine wave target generated force when a time t = 0.3 s was generated. Figure 8(A) shows the results without any dead time countermeasures, and Figure 8(B) shows the results with dead time countermeasures. In the result of Figure 8(A), where no dead time countermeasures were taken, it can be seen that the actuator force is oscillating and the control system is unstable. In addition, the rod length p was also oscillating greatly, which was dangerous, so the experiment was stopped around t = 30 s. As shown in Figure 8(B), when dead time countermeasures were taken, it can be seen that the actuator force tracks the target generated force and stable control is possible.

[0069] From the above results, it can be seen that the control device and control method relating to force control according to the first and second embodiments can perform force control relating to the contact force between the control target and the external environment with high control performance despite a simple configuration.

[0070] Example 2 As in Example 1, an experiment was conducted to confirm the control performance of the position control law according to the third and fourth embodiments using the hydraulic testing machine shown in FIG. 5. The parameter for the control law was H=0.2 s. The upper and lower limits of the velocity saturation after correction to counter the dead time were set to [-v m ,v p ]=[-2×10 -2 m / s, 2×10 -2 m / s].

[0071] The experimental results of position control are shown in Figures 9(A) and (B). Figure 9(A) shows the experimental results when the target position is changed in a stepwise manner, and Figure 9(B) shows the experimental results when the target position is changed in a sine wave manner. In the step response shown in Figure 9(A), the rod length p reaches the target position p without any overshoot. d In the case of tracking the sine wave shown in Figure 9(B), the rod length p converges to the target position p without any significant position error. d It can be seen that it follows the

[0072] Figure 10(A) and (B) show the dead time T d= 0.1 s, Fig. 10(A) shows the results without dead time countermeasures, and Fig. 10(B) shows the results with dead time countermeasures. In both cases, the target position is converged, and as shown in Fig. 10(B), it can be seen that when dead time countermeasures are used, overshooting is kept small.

[0073] Figure 11(A) and (B) show the dead time T d Figure 11(A) shows the results of a position control experiment when dead time was generated, with dead time = 0.3 s, and Figure 11(B) shows the results when dead time was reduced. In the case of Figure 11(A) where no dead time reduction measures were taken, large vibrations with a period of approximately 0.05 s were generated due to the effects of dead time. In the case of Figure 11(B) where dead time reduction measures were taken, the steady vibrations were suppressed by the dead time reduction measures, and although overshooting occurred, the target position was converged on around t = 7 s.

[0074] From the above results, it can be seen that the control device and control method according to the position control of the third and fourth embodiments are capable of performing positioning control of a control target with high control performance despite a simple configuration. [Industrial Applicability]

[0075] The present invention is suitable for force and position control of machines operated by hydraulic actuators. [Explanation of symbols]

[0076] 10,10' Force control device, 11,11' Position control device, 101,111 Control unit, 1011,1111 Reference speed calculation unit, 1012,1112 Manipulation amount calculation unit, 1013,1113 Reference speed update unit, 102 Memory unit, 103 Input unit, 30 Control target, 31 Hydraulic actuator, 311a Hydraulic pump, 311b Pump relief valve, 311c Bleed valve, 311d Pump check valve, 312 Main control valve, 313a Rod side relief valve, 313b Rod side check valve, 314a Head side relief valve, 314b Head side check valve, 315 Cylinder, 316 Regeneration circuit, 316a Check valve, 316b Flow control valve, 32 Force sensor, 33 Position sensor, 40 External environment

Claims

1. a control unit that determines an operation amount of a hydraulic actuator that drives a controlled object; The control unit a reference speed calculation unit that calculates a reference speed, which is a speed to be achieved at a next time step of the controlled object, based on a measurement value of the generated force of the hydraulic actuator or a force measurement value that is a measurement value of a force at which the controlled object comes into contact with an external environment that is an object, and a target generated force of the hydraulic actuator; an operation amount calculation unit that calculates an operation amount of the hydraulic actuator based on the quasi-static characteristic of the hydraulic actuator, the reference velocity, and the force measurement value, A control device characterized by:

2. The reference speed is is a velocity at the next time point calculated by simulating the motion of a virtual object having predetermined dynamic characteristics when the target generated force and the force measurement value are applied to the virtual object.

2. The control device according to claim 1.

3. The control unit a reference speed update unit that updates the reference speed using a plant energy amount that is an energy amount of the controlled object and the external environment and an energy amount of the hydraulic actuator when the hydraulic actuator has a dead time that is a time delay in operation with respect to an input of an operation amount, 3. The control device according to claim 1 or 2.

4. The reference speed update unit calculating a target energy amount based on the target generated force; calculating an estimated plant energy amount that is an estimate of the plant energy amount after a dead time has elapsed; estimating a work of the hydraulic actuator when the manipulated variable is calculated using the reference speed before updating; updating the reference speed so that the reference speed is within a predetermined range when the estimated plant energy amount at the next time step deviates from the target energy amount or when the estimated plant energy amount at the next time step exceeds the target energy amount due to work by the hydraulic actuator; 4. The control device according to claim 3.

5. calculating a reference speed, which is a speed to be achieved at a next time step of the controlled object, based on a measured value of a generated force of a hydraulic actuator that drives the controlled object or a force measurement value that is a measured value of a force at which the controlled object comes into contact with an external environment that is an object, and a target generated force of the hydraulic actuator; calculating an operation amount of the hydraulic actuator based on the quasi-static characteristic of the hydraulic actuator, the reference velocity, and the force measurement value; A control method comprising:

6. a control unit that determines an operation amount of a hydraulic actuator that drives a controlled object; The control unit a reference speed calculation unit that calculates a reference speed, which is a speed that should be achieved at a next time step of the controlled object, based on a target position and a measured position of the controlled object; an operation amount calculation unit that calculates an operation amount of the hydraulic actuator based on the quasi-static characteristic of the hydraulic actuator, the reference velocity, and a force measurement value that is a measurement value of the force generated by the hydraulic actuator, A control device characterized by:

7. The reference speed is proportional to the difference between the target position and the measured position and the target velocity of the controlled object; 7. The control device according to claim 6.

8. The control unit a reference speed update unit that updates the reference speed using an amount of energy of the hydraulic actuator and an amount of energy of the controlled object when the hydraulic actuator has a dead time that is a time delay in operation with respect to an operation amount input, 8. The control device according to claim 6 or 7.

9. The reference speed update unit calculating a target energy amount based on the reference speed; calculating an estimated controlled object energy amount, which is an estimated value of the controlled object energy amount after the dead time has elapsed; estimating a work of the hydraulic actuator when the manipulated variable is calculated using the reference speed before updating; updating the reference speed so that the reference speed is within a predetermined range when the estimated controlled energy amount at the next time step deviates from the target energy amount or when the estimated controlled energy amount at the next time step exceeds the target energy amount due to work by the hydraulic actuator; 9. The control device according to claim 8.

10. calculating a reference speed, which is a speed to be achieved at a next time step of a controlled object driven by a hydraulic actuator, based on a target position and a measured position of the controlled object; calculating an operation amount of the hydraulic actuator based on the quasi-static characteristic of the hydraulic actuator, the reference velocity, and a force measurement value that is a measurement value of a generated force of the hydraulic actuator; A control method comprising:

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