WO2024043303A1

WO2024043303A1 - Control device and control method

Info

Publication number: WO2024043303A1
Application number: PCT/JP2023/030465
Authority: WO
Inventors: 亮菊植; 裕貴山本
Original assignee: コベルコ建機株式会社; 国立大学法人広島大学
Priority date: 2022-08-26
Filing date: 2023-08-24
Publication date: 2024-02-29

Abstract

This control device comprises: an operation command unit that controls cylinders (44-46) for driving an excavator, which is a controlled object; an ideal speed calculation unit that calculates an ideal speed to be generated at a next time step on the basis of a target position and a current position of a bucket tip (43a); a reference speed calculation unit that calculates a reference speed, which is closest to the ideal speed within the range of actuator force that can be generated when PID control is implemented in the cylinders, and a reference generated force for when PID control is implemented at the reference speed, from quasi-static characteristics of the cylinders; and a manipulated variable calculation unit that calculates a manipulated variable on the basis of the quasi-static characteristics of the cylinders, the reference generated force, and the reference speed.

Description

Control device and control method

The present invention relates to a control device and a control method for controlling the position of a controlled object driven by a hydraulic actuator or the force acting on the controlled object.

In machines such as excavators that are driven by hydraulic actuators, control methods have been developed to automatically move buckets, work equipment, etc. to target positions. The response characteristics of hydraulic actuators, including hydraulic actuators, have strong nonlinearity and vary greatly depending on whether a relief valve is opened or closed. Therefore, it is difficult to realize automatic positioning control using a simple control law.

In addition, when performing force control on a machine driven by a hydraulic actuator, specifically when performing admittance control on the force acting on a controlled object in contact with the external environment, the strong nonlinearity of hydraulic actuators makes simple control possible. It is difficult to achieve this by following the rules.

In Patent Document 1, a prediction equation for predicting the position and velocity of the controlled object at the next time step and an equation representing a sliding mode control law are solved as simultaneous equations based on prior information on the dynamic characteristics of the controlled object, and the manipulated variable is The control algorithm is simplified by calculating the valve opening command to the hydraulic actuator.

JP 2021-121717 Publication

In the control method of Patent Document 1, the dynamic characteristics of the controlled object are used when calculating the valve opening command to the hydraulic actuator. However, if the prior information on 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 guaranteed and the desired control characteristics cannot be obtained. There is a possibility that it is not.

An object of the present invention is to obtain high control performance for position control or force control even when the accuracy of prior information regarding the dynamic characteristics of a controlled object is low or when there is a time delay in the response of a hydraulic actuator. The objective is to provide a control device and a control method that can

A control device according to a first aspect of the present invention includes an operation command unit that controls a hydraulic actuator that drives a machine to be controlled, and a next time step of the machine based on a target position and a current position of the machine. an ideal speed calculation unit that calculates the ideal speed that should be generated at A reference speed that is a similar speed and a reference generated force that is an actuator force that should be generated when PID control or PD control is performed using the reference speed as a target speed are determined based on the quasi-static characteristics of the hydraulic actuator. the hydraulic actuator, and an operation amount calculation section that calculates the operation amount of the hydraulic actuator based on the quasi-static characteristics of the hydraulic actuator, the reference generated force, and the reference speed.

Further, the control method according to the second aspect of the present invention is based on the target position and current position of a machine to be controlled driven by a hydraulic actuator, and the ideal speed to be generated in the next time step of the machine. and a reference speed which is the speed closest to the ideal speed among the target speeds at which the actuator force that can be generated when PID control or PD control is implemented with the hydraulic actuator. , a reference speed calculation step of calculating a reference generated force, which is an actuator force that should be generated when PID control or PD control is performed with the reference speed as a target speed, based on the quasi-static characteristics of the hydraulic actuator. and a manipulated variable calculating step of calculating a manipulated variable of the hydraulic actuator based on the quasi-static characteristic of the hydraulic actuator, the reference generated force, and the reference speed.

FIG. 1 is a schematic diagram showing the configuration of a hydraulic actuator according to Embodiment 1 of the present invention. FIG. 2 is a side view schematically showing the shovel according to the first embodiment. FIG. 3 is a block diagram showing the configuration of the control system according to the first embodiment. FIG. 4 is a conceptual diagram showing a method of controlling a plurality of hydraulic actuators. FIG. 5 is a flowchart showing the flow of position control according to the first embodiment. FIG. 6 is a diagram showing the attitude of the hydraulic excavator and the trajectory of the target position according to a numerical example. FIG. 7A is a conceptual diagram showing the flow of processing in a control law, and is a diagram in the case of a conventional control law. FIG. 7B is a conceptual diagram showing the flow of processing in the control law, and is a diagram in the case of the control law according to Embodiment 1 of the present invention. FIG. 8 is a diagram showing simulation results using a conventional control law and a control law according to Embodiment 1 of the present invention. FIG. 9A is a diagram showing simulation results for comparing the effects of modeling errors, and is a diagram for the case of the control law according to Embodiment 1 of the present invention without reproducing circuit compensation. FIG. 9B is a diagram showing simulation results for comparing the effects of modeling errors, and is a diagram for the case of the control law according to the first embodiment of the present invention with reproducing circuit compensation. FIG. 9C is a diagram showing simulation results for comparing the effects of modeling errors, and is a diagram for a conventional control law. FIG. 10 is a block diagram showing the configuration of a control system according to the second embodiment. FIG. 11 is a functional block diagram showing the configuration of a control system according to the second embodiment. FIG. 12 is a flowchart showing the flow of force control according to the second embodiment. FIG. 13 is a conceptual diagram showing the configuration of a hydraulic testing machine according to a numerical example. FIG. 14A is a graph showing a simulation result related to a numerical example in the case of stepped input, and is a graph when the hardness of the contact environment is 50HS. FIG. 14B is a graph showing a simulation result related to a numerical example in the case of stepped input, and is a graph when the hardness of the contact environment is 65HS. FIG. 14C is a graph showing a simulation result regarding a numerical example in the case of stepped input, and is a graph when the hardness of the contact environment is 70HS. FIG. 15A is a graph showing simulation results according to a numerical example in the case of a sine wave input, and is a graph when the hardness of the contact environment is 50HS. FIG. 15B is a graph showing a simulation result related to a numerical example in the case of a sine wave input, and is a graph when the hardness of the contact environment is 65HS. FIG. 15C is a graph showing simulation results regarding a numerical example in the case of a sine wave input, and is a graph when the hardness of the contact environment is 70HS.

<Embodiment 1>
Hereinafter, among the control devices and control methods according to embodiments of the present invention, a control device and control method related to position control will be described with reference to the drawings.

<Control algorithm>
First, a description will be given of the control law according to the present embodiment, that is, the control algorithm for determining the operation amount u of the hydraulic actuator when a machine driven by a hydraulic actuator is the controlled object and the controlled object is moved to a target position. do. Specifically, consider the hydraulic actuator 1 shown in FIG. 1 as a hydraulic actuator.

As shown in FIG. 1, the hydraulic actuator 1 includes a hydraulic pump 11a that supplies hydraulic pressure, a pump relief valve 11b, a bleed valve 11c, a pump check valve 11d, a main control valve 12 that controls hydraulic pressure, a rod-side relief valve 13a, and a rod. It includes a side check valve 13b, a head side relief valve 14a, a head side check valve 14b, and a cylinder 15 operated by hydraulic control. The hydraulic actuator 1 also includes a regeneration circuit 16, and the regeneration circuit 16 includes a check valve 16a and a flow control valve 16b.

<Mathematical preparation>
In this embodiment, the closed unit sphere B and functions shown in the following equations (1), (2), (3), and (4) are used.

Also, a function that takes a set value as an argument is handled as shown in equation (5) below.

Here, X represents a real closed interval.

<Control law>
The hydraulic actuator is expressed by the following equations (6a), (6b), and (6c).

Here, p represents the position of the controlled object, v represents the speed of the controlled object, and M represents the mass of the controlled object.

Actuator force f and external force g act on the controlled object in the above equation. The set value function Γ is a quasi-static model of the hydraulic actuator, and is given as a set value function from the current speed v and the manipulated variable u, which is the valve opening command, to the actuator force f. A concrete example of the set-valued function Γ, which is a quasi-static model of the hydraulic actuator 1 that is driven with the regeneration circuit 16 removed from the hydraulic circuit of the hydraulic actuator 1 in FIG. 1, that is, with the regeneration circuit 16 always closed. The shape is described in the 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 .1210 02, 2021), and the well-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) is shown in equation (24).

The manipulated variable uεB, which is the second argument of the function Γ, is a variable that indicates the degree of opening of the four main control valves 12 shown in FIG. The manipulated variable u and the opening degree u _* ∈[0,1](*∈{ph, pr, th, tr}) of the main control valve 12 have a relationship expressed by the following equation (7).

From the above relational expression (7), the manipulated variable u, which is a positive control input, becomes a command to extend the cylinder, and the manipulated variable u, which is a negative control input, becomes a command to retract the cylinder.

In this embodiment, position control laws for the hydraulic actuator shown in the following equations (8a), (8b), (8c), and (8d) are used.

Here, K, L, D are PID gain, H is time constant, _pd is target position, p is current position, vr is reference speed, u is command to actuator, f^ is reference generated force of actuator, a is the error integral value of the PID controller. Moreover, g is an estimated value of external force. If an estimated value of the external force cannot be obtained, g may be set to 0, but if an estimated value can be obtained, better control performance can be obtained by setting the value to g.

Further, the function Θ is an inverse function regarding the second argument of the set-valued function Γ, and is a set-valued function that has a relationship with the set-valued function Γ according to the following equation (9).

Equation (8a) is a PID control law constructed based on the speed p ^· and the reference speed _vr . Further, equation (8b) is a sliding mode control law using equation (10) below as a switching plane.

In this embodiment, the PID control law of equation (8a) and the sliding mode control law of equation (8b) are combined. Hereinafter, this method will be referred to as differential algebraic relaxation. In the sliding mode control law of Equation (8b), since the right side is a set value, the value is not uniquely determined, and it is not suitable for implementation alone. However, by combining it with the PID control law of equation (8a), this problem can be avoided and the reference generated force f^ can be calculated (calculated, the same applies hereafter). Note that in each formula, symbols such as dots placed above the symbols are placed after the symbols in the main text, but both indicate the same thing.

<Discrete time algorithm>
To implement the above control law, we consider a control algorithm in discrete time. By discretizing the control law of Equation (8) (Equations (8a) to (8d)) using the backward Euler method, the following Equation (11) (Equation (11f) from Equation (11a)) is obtained. be able to.

Here, T is a sampling interval and kεZ is a discrete time index.

When v _r,k and a _k are eliminated from equation (11b) using equation (11a) and equation (11d), the following equation (12) (from equation (12a) to equation (12c)) is obtained.

Here, A=ΔLT ² +KT+D (=Δ corresponds to a symbol in which Δ is arranged vertically above =, as shown in Equation 12).

Here, v _s , _k can be interpreted as the ideal speed to be achieved in the next step by the sliding mode control law. Further, v _f , _k can be interpreted as a temporary target speed such that the force generated by the hydraulic actuator becomes 0 when the PID control law is implemented with the hydraulic actuator.

Known document 3 (R. Kikuuwe, Y. Yamamoto, and B. Brogliato, “Implicit implementation of nonsmooth controllers” to nonsmooth actuators,” IEEE Trans. Autom. Control, 10.1109/TAC.2022.3163124, 2022), It is shown that the following equation (13) holds true.

By using equation (13), equation (12a) can be rewritten as equation (14) below.

As a result, the algorithm of formula (15) below (formula (15a) to formula (15f)) for determining the control input u _k from the state {p _k , v _k , p _d , _k , v _d , _k } is obtained. .

Here, the function Γ _s and the function Θ _s are single-valued functions that have a relationship with the function Γ and the function Θ as shown in the following equations (16) and (17).

As described above, the set value function Γ can be obtained from the quasi-static characteristics of the hydraulic actuator (the relationship among the speed v at steady speed, the generated force f, and the manipulated variable u that is the valve opening command). Further, the set-valued function Θ can be obtained from the set-valued function Γ using equation (9). Using these relationships, Equation (16), and Equation (17), the single-valued function Γ _s and the single-valued function Θ _s can be obtained. Specifics of the single-valued function Γ _s and the single-valued function Θ _s of the hydraulic actuator 1 that is driven in a state in which the regeneration circuit 16 is removed from the hydraulic circuit of the hydraulic actuator 1 shown in FIG. 1, that is, in a state in which the regeneration circuit 16 is always closed. The formula (34) of the well-known document 2 and III. Each is shown in Section C.

Note that the pair of the generated force f _k that can be generated by the hydraulic actuator 1 at time k and the target speed v _r , _k that produces the generated force f _k is a real number that satisfies the following two equations (18a) and (18b). is the pair {f _k ^, v _r , _k }.

There are an infinite number of such pairs. On the other hand, the pair {f _k ^, v _r , _k } obtained by equations (15b), (15c), and (15d) is an infinite number of pairs {f _k ^, v _r , _k } that satisfy equation (18). Among them, v _r , _k is closest to v _s , _k . That is, Equations (15b), (15c), and (15d) calculate the ideal speed v _s , among the target speeds v _f , _k at which the actuator force that can be generated when the hydraulic actuator 1 performs PID control is calculated. Reference generated force f _{k ^} which is the actuator force to be generated when PID control is performed using the reference speed v _r , _k which is the speed closest to _k and the reference speed v _r , _k as the target speed v _f , _k This is a step (reference speed calculation step) of calculating this based on the quasi-static characteristics of the hydraulic actuator.

Note that when L=0 in the algorithm of equation (15), a problem arises in that a _k can become infinitely large. In this case, the algorithm of equation (15) can be changed from equation (19a) to equation (19f) using a new variable e _k defined by e _k = (a _k - _{a k-1} )/T. can be corrected.

Here, A=△KT+D (=△ corresponds to a symbol in which △ is arranged above and below =).

The algorithm expressed by the above equation (19) replaces a ^· with e in the equation (8) to set L=0, discretizes using the backward Euler method, and performs the same derivation procedure as the above equation (15). It can also be derived by going through . Equation (19) makes it possible to replace the PID control of Equation (15) with PD control with integral gain L=0.

In the conventional control law according to the known document 2, which is a control law based on a quasi-static model like the present embodiment, a double implicit implementation method is used to deal with the set value nature of the sliding mode control law. There is. In the double-implicit implementation method, a control algorithm is constructed by discretizing both the control law and the dynamic characteristic model of the controlled object using the backward Euler method and combining them. The control method based on differential algebraic relaxation according to the present embodiment does not require a dynamic characteristic model for implementation, so it has a structure that is more resistant to modeling errors than conventional control methods. Furthermore, sensitivity to modeling errors and dead time can be adjusted by adjusting the gains of the PID controllers that are coupled through differential algebraic relaxation.

As shown in the algorithm of equation (19), in the position control according to the present embodiment, the target position p _d , _k and the current position p _k of the hydraulic actuator, more specifically, the target position p _d , _k and the current position Based on _pk , the target speed _vd , _k derived from these, and the current speed _vk , the ideal speed _vs , _k to be generated by the hydraulic actuator at the next time step is calculated (ideal speed calculation step , formula (19a)). Then, among the target speeds v _f , _k at which the actuator force f that can be generated when PID control or PD control is performed with the hydraulic actuator is calculated, a reference speed v is the speed closest to the ideal speed v _s , _k . _r , _k and a reference generated force f _k ^ which is the actuator force to be generated when PID control or PD control is performed with the reference speed v _r , _k as the target speed, using a quasi-static model of the hydraulic actuator. Calculate based on Γ (reference speed calculation step, equations (19b) to (19e)). Furthermore, the operation amount u _k of the hydraulic actuator is calculated based on the quasi-static model Γ of the hydraulic actuator, the calculated reference generated force f _k ^, and the reference speed v _r , _k (operation amount calculation step, formula (19f)).

<Compensation for the influence of the reproduction circuit>
The hydraulic actuator 1 includes a regeneration circuit 16 as shown in FIG. The regeneration circuit 16 uses the potential energy of the link to send hydraulic fluid from the rod-side chamber to the head-side chamber. If the cross-sectional area of the rod-side chamber is A _r and the cross-sectional area of the head-side chamber is A _h , and A ⁻ = (A _r +A _h )/2, then the distance between the rod-side chamber and the head-side chamber generated by external force g is The pressure difference can be approximated by g/A ^- . Since the flow rate in the flow rate control valve 16b is proportional to the square root of the pressure difference between both chambers, the estimated value of the flow rate q _reg of the hydraulic oil passing through the regeneration circuit is obtained by the following equation (20).

Here, u _reg indicates the opening degree of the flow rate control valve 16b of the regeneration circuit 16. The coefficient c _reg is defined as C _reg a _reg √2/ρ, where ρ is the mass density of the hydraulic oil, a _reg is the maximum opening area of the flow control valve 16b, and C _reg is the outflow coefficient.

The increment v _reg of the cylinder speed due to the flow rate q _reg of the regeneration circuit 16 is determined as v _reg =q _reg /A _h . Furthermore, the variable v _reg takes on a non-negative value due to the effect of the check valve 16a of the regeneration circuit 16. Based on this cylinder speed increment v _reg , the control law of equation (8) is extended to compensate for the influence of the regeneration circuit 16, and the following equations (21a), (21b), and (21c) are shown. A control law is obtained.

By introducing the above variable v _reg , the switching plane becomes p _d −p+H(p _d ^· −v _r −v _reg )=0 in the situation where the hydraulic oil is sent to the head side chamber through the regeneration circuit 16. Become. As a result, the switching plane is reached at a lower speed by v _reg than in the case without compensation, so that control can be performed that suppresses excessive speed increases.

An algorithm for implementing the control law including the variable v _reg can be obtained by discretizing the control law of Equation (21) by applying a procedure similar to the derivation of the algorithm of Equation (15). The derived algorithm is obtained by replacing equation (15a) of the algorithm expressed by equation (15) with equation (22) below.

The value of the variable v _reg , _k may be calculated for each time step related to the calculation using equation (20). Moreover, at this time, the gravity acting on the cylinder 15 derived from the joint angle and the mass of the link can be used as the external force g.

<Control system configuration>
In this embodiment, as an example of a specific control system configuration, a case will be described in which the position of a bucket of an excavator driven by a plurality of hydraulic actuators is controlled.

A control unit 50, which is a position control device according to this embodiment, is mounted on the shovel 30 shown in FIG. 2 and controls the operation of the shovel 30.

The excavator 30 includes a lower traveling body 31, an upper revolving body 32, and a working device 40. The lower traveling body 31 is a portion on which the excavator 30 travels, and is, for example, a crawler. The upper rotating body 32 is rotatably attached to the lower traveling body 31 via a rotating motor 47 . A driver's cab in which an operator operates the shovel 30, a working device 40, and the like are arranged in the upper revolving body 32.

The working device 40 includes a boom 41 rotatably attached to the upper revolving structure 32, an arm 42 rotatably attached to the boom 41, and a bucket 43 rotatably attached to the arm 42 for digging and the like.

The working device 40 also includes a boom cylinder 44 connected to the upper revolving body 32 and the boom 41 to operate the boom 41, an arm cylinder 45 connected to the boom 41 and the arm 42 to operate the arm 42, an arm 42, and a bucket 43. The bucket cylinder 46 is connected to the bucket cylinder 46 to operate the bucket 43, and the swing motor 47 is connected to the lower traveling body 31 and the upper rotating body 32 to operate the upper rotating body 32. The boom cylinder 44, arm cylinder 45, bucket cylinder 46, and swing motor 47 (hereinafter also referred to as actuators 44 to 47) are hydraulic actuators driven by hydraulic pressure.

The control unit 50 is mounted on the excavator 30, and includes a control section 51, a storage section 52, a display section 53, and an input section 54, as shown in the block diagram of FIG. The control unit 50 is connected to a position sensor 48, a speed sensor 49, each actuator 44 to 47, etc., and controls the operation of each part of the shovel 30.

The control unit 51 is a computer device including a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), etc., and controls the operation of the shovel 30. The control unit 51 performs each function as the control unit 51 shown in FIG. 3 by loading various operating programs and data stored in the ROM, storage unit 52, etc. of the control unit 51 into the RAM and operating the CPU. make it happen. As a result, the control unit 51 includes the ideal speed calculation unit 511 (ideal speed calculation unit), the reference speed calculation unit 512 (reference calculation calculation unit), the operation amount calculation unit 513 (operation amount calculation unit), the external force estimation unit 514, and the operation It operates as a command unit 515.

The ideal speed calculation section 511, the reference speed calculation section 512, and the operation amount calculation section 513 calculate the measured values that are the outputs of the position sensor 48 and the speed sensor 49, and the target position of the bucket 43, more specifically, at a predetermined position of the excavator 30. Based on the target position of the tip of a certain bucket 43 (hereinafter referred to as bucket tip 43a), the operation amount u of each actuator 44 to 47 for operating the working device 40 is calculated.

The external force estimation unit 514 estimates the magnitude of the external force acting on each actuator 44 to 47. The method for estimating the external force is not particularly limited, and can be estimated based on the output of a sensor (not shown) installed on each actuator 44 to 47, for example.

The operation command section 515 controls each of the actuators 44 to 47 based on the operation amount u calculated by the operation amount calculation section 513, and operates the upper revolving structure 32, boom 41, arm 42, and bucket 43.

The storage unit 52 is a nonvolatile memory such as a hard disk or a flash memory, and stores various setting parameters, control algorithms for calculating the manipulated variable u, and the like.

The display unit 53 is a display device such as a liquid crystal panel or an organic EL (electroluminescence), and displays various setting parameters, detected values of the position sensor 48 and speed sensor 49, and the like. The display unit 53 according to this embodiment is a liquid crystal panel installed in the driver's cab of the excavator 30.

The input unit 54 is an input device for inputting various setting parameters for operating the shovel 30, such as the target position of the bucket tip 43a. The input unit 54 is, for example, a touch panel placed on the display unit 53.

The position sensor 48 is a sensor that detects the position of the working device 40 of the excavator 30 to be controlled, and the position sensor 48 according to the present embodiment includes a swing angle sensor 484 that detects the angle of the upper swing structure 32, The boom angle sensor 481 detects the angle of the arm, the arm angle sensor 482 detects the angle of the arm, and the bucket angle sensor 483 detects the angle of the bucket. The control unit 51 controls the boom cylinder 44, arm cylinder 45, and bucket cylinder 46 (hereinafter referred to as The length of each cylinder 44 to 46 (also referred to as 46) and the angle of the swing motor 47 are calculated, and the position of the bucket tip 43a is controlled based on the calculated length of each cylinder 44 to 46 and the angle of the swing motor 47. I do.

The speed sensor 49 is a sensor that detects the speed of each part of the working device 40, and the speed sensor 49 according to the present embodiment includes a swing angular velocity sensor 494 that detects the angular velocity of the upper rotating body 32, and a swing angular velocity sensor 494 that detects the expansion and contraction speed of the boom cylinder. An arm speed sensor 492 detects the expansion/contraction speed of the arm cylinder, and a bucket speed sensor 493 detects the expansion/contraction speed of the bucket cylinder.

The position control process of the bucket tip 43a by the control unit 50 according to the present embodiment will be described below. As shown in the block diagram of FIG. 4, a control algorithm for calculating the operation amount u of each cylinder 44 to 46, which are hydraulic actuators, will be explained as an example. Note that in the following embodiment, only each of the cylinders 44 to 46 is used, but the invention is not limited to this. The position of the bucket tip _43a may be controlled by configuring a controller that adds the rotation angle of the upper rotating body 32 to the coordinates of the target position pd. More specifically, as shown in FIG. 3, a swing angle sensor 484 as the position sensor 48 and a swing angular velocity sensor 494 as the speed sensor 49 are used to operate the swing motor 47, which is a hydraulic actuator, and the boom 41 , the arm 42, and the bucket 43 to control the position of the bucket tip 43a.

In the control algorithm of the present invention, the control unit 51 calculates the operation amount u of each cylinder 44 to 46 based on the target position, desired behavior, current position, current speed, etc. of the given controlled object. The desired behavior is, for example, the time constant of the convergence movement of the controlled object to the target position.

<Control flow>
The flow of position control of the bucket tip 43a of the shovel 30 will be specifically described with reference to the flowchart in FIG.

The operator of the excavator 30 inputs and sets the target position _pd of the bucket tip 43a from the input unit 54 (step S11). The target position _pd may be entered by inputting coordinates using the input unit 54, which is a touch panel, or by setting the coordinates of the bucket tip 43a manually moved using an operating lever as the target position _pd . good. Alternatively, the target position _pd may be set by reading the coordinates on the design surface that are stored in advance in the storage unit 52.

The operator also inputs and sets parameters such as the time constant H that represents the desired behavior. These parameters may be set by reading values stored in advance in the storage unit 52.

The control unit 51 calculates the target length of each cylinder 44 to 46 at the target position p _d from the input target position p _d by inverse kinematics (step S12). Then, as shown in FIG. 4, the position of the bucket tip 43a is controlled by controlling the cylinders 44 to 46 to expand and contract so that the lengths of the cylinders 44 to 46 become the respective target lengths.

The ideal speed calculation unit 511 of the control unit 51 calculates the ideal speed v _s , _k to be generated at the next time step as an ideal speed calculation step (step S13). More specifically, the control unit 51 acquires angle data of each part of the working device 40 from a boom angle sensor 481, an arm angle sensor 482, and a bucket angle sensor 483 (hereinafter also referred to as each angle sensor 481 to 483). . The control unit 51 calculates the current position p _k , which is the length of each cylinder 44 to 46, based on the acquired angle data. The control unit 51 calculates the calculated current position p _k (m), the set target position p _d , _k (m), the target speed v _d , _k (m/s), the time constant H (s), and the equation (15a). ) or the ideal speed v _s , _k of each cylinder 44 to 46 is calculated based on equation (22). The control period is, for example, 10 ms (milliseconds), although it is not particularly limited.

Subsequently, the reference speed calculation unit 512 of the control unit 51 calculates the current speed vk (m/sec), the set PID gains K, L, D, the control period T (sec), and the formula ( 15b) to (15e) or equations (19b) to (19e), the reference speed vr, _k and reference generated force f _k ^ of the next time step are calculated (step S14). More specifically, the reference speed calculation unit 512 obtains the current speed v _k of each cylinder 44 to 46 from the boom speed sensor 491, arm speed sensor 492, and bucket speed sensor 493. Then, the reference speed calculation unit 512 selects the ideal speed v _s , _k that is the most suitable among the target speeds v _f , k for which the actuator force f that can be generated when PID control or PD control is performed with the hydraulic _actuator is calculated. The reference speed v _r , _k which is a similar speed and the reference generated force f _k ^ which is the actuator force that should be generated when PID control or PD control is performed with the reference speed v _r , _k as the target speed are Calculated based on the quasi-static model Γ of the pressure actuator.

Subsequently, the manipulated variable calculation unit 513 of the control unit 51 calculates the manipulated variables u _k of each cylinder 44 to 46 as a manipulated variable calculation step (step S15). Specifically, the operation amount calculation unit 513 calculates the operation amount u k based on the reference speed v _r , _k and the reference generated force f _k ^ calculated in step S14, and the quasi-static model Γ of the hydraulic actuator _. is calculated (Equations (15f), (17)).

The operation command unit 515 of the control unit 51 outputs the calculated operation amount u _k to each cylinder 44 to 46, and operates the boom 41, arm 42, and bucket 43 to move the bucket tip 43a (step S16).

When the next time step is reached, the control unit 51 newly acquires the current position p _k of each cylinder 44 to 46 from the position sensor 48. If the difference between the acquired current position p _k and target position p _d , _k is less than or equal to a predetermined threshold (YES in step S17), the control unit 51 ends the position control.

Further, if the difference between the acquired current position p _k and target position p _d , _k is larger than a predetermined threshold value set in advance (NO in step S17), the control unit 51 performs the ideal speed calculation process in step S13. return. Then, the control unit 51 calculates the operation amount u _k at the time step in accordance with the control algorithm, and moves the bucket tip 43a. By repeating this, the control unit 51 performs position control so that the position of the bucket tip 43a is set to the target position _pd .

As described above in detail, the control device and control method for position control of this embodiment uses a PID control law or a PD control law for making the speed of a controlled object follow a reference speed, and a sliding mode control law. Since the reference speed and actuator force are calculated simultaneously, and the operation amount of the hydraulic actuator is calculated based on the quasi-static characteristics of the hydraulic actuator, control can be performed without depending on the dynamic characteristic model of the controlled object. . Therefore, even when the accuracy of prior information on the dynamic characteristics of the controlled object is low or when there is a time delay in the response of the hydraulic actuator, it is possible to obtain high control performance.

<Numerical example>
Hereinafter, a position control simulation of a hydraulic actuator using the control law according to the present embodiment will be explained. In this example, the simulation was performed using a real-time simulator for a 13-ton class hydraulic excavator. Further, in this example, the arm tip position was controlled by applying the control law according to the present embodiment to the actuator of each axis using kinematics. Further, the sampling interval of the real-time simulator is 0.1 ms, and the sampling interval of the controller is 10 ms. The real-time simulator and the controller are connected by UDP/IP (User Datagram Protocol/Internet Protocol), and can transmit and receive joint angle information, control inputs, and the like.

The cylinder force generated in the real-time simulator is calculated based on the quasi-static model of the hydraulic actuator described in the above-mentioned known document 1. Further, the arm cylinder generated force is calculated based on a quasi-static model including a regeneration circuit described in the well-known document 1. In this example, in order to simulate the dynamic characteristics of the hydraulic actuator and the dead time within the hydraulic actuator, a filter expressed by the following equation (23) is installed between the actuator model and the controller.

Here, u _f is the filtered control input. Furthermore, the dead time T _d , the cutoff frequency ω ₀ , and the damping ratio ζ were set to T _d =300 msec, ω ₀ =94.2 rad/sec, and ζ=1, respectively.

FIG. 6 shows the attitude of the shovel 30 and the trajectory of the target position _qd . The target position q _d and the rate of change over time of the target position q _d are as shown in equation (24) below, and the magnitude of the rate of change over time of the target position q _d is constant.

Further, as parameters in this example, K=3×10 ⁵ N/m, B=3×10 ⁵ N·s/m, and H=1.0 s for both the boom 41 and arm 42 of the excavator 30. Furthermore, the parameters of the actuator model in the control law were set to the same values as the parameters of the controlled object.

Furthermore, in order to compare the control method according to this embodiment with a conventional control method, a control simulation was performed under the same conditions. Specifically, the control law A is a conventional sliding mode control law (control law according to known document 2) based on the double implicit implementation shown in FIG. 7A, and the control law B is the present implementation shown in FIG. 7B. A PID control law according to the form was used. Since the control law A includes a dead time compensator, simulations were performed with the look-ahead time T _d ^ set to 300 ms (=T _d ), 150 ms, and 0 ms, respectively. Further, the time constant H indicating the inclination of the switching plane was set to 1.0 s.

Control law B is expressed by the following formula (25) (formula (25a), formula (25b)).

Here, the proportional gain K _p , the differential gain K _d and the integral gain K _i were set to 3×10 ⁸ N/m, 3×10 ⁸ N·s/m, and 0, respectively. These gain values were adjusted by trial and error through repeated simulations.

FIG. 8 is a diagram showing the simulation results. As shown in FIG. 8, the control method according to the present embodiment (proposed method in the figure) with regenerative circuit compensation enabled is effective in controlling the target position and the arm tip position (hand position in FIG. 8; also in subsequent figures) over the entire range. (similar) gave the best result with the least error. In the control method (control law B) according to the present embodiment without reproducing circuit compensation, errors are large due to the influence of the reproducing circuit during vertical lowering and horizontal pulling when the reproducing circuit opens.

Control law A always resulted in errors during leveling. Furthermore, when the look-ahead time Td = 0 (no dead time compensation), the hand position always oscillated. Control law B also resulted in oscillations over the entire range.

<Verification of influence of modeling errors>
A simulation was conducted to verify the influence of parameter errors in the hydraulic actuator model on control performance. An error of {-20%, 0, +20%} was randomly added to the parameters on the control law side based on values such as relief pressure and outflow coefficient on the simulator side. The number of trials was 100. Further, for comparison, similar simulations were performed using the control method according to the present embodiment and control law A based on a quasi-static model of a hydraulic actuator.

FIGS. 9A, 9B, and 9C are diagrams showing simulation results. Comparing FIG. 9C using control law A, FIG. 9A using control law B without regeneration circuit compensation, and FIG. 9B using control law B with regeneration circuit compensation, FIGS. 9A and 9B are better. The trajectories of simulation results (trajectories with parameter errors) are clustered near the trajectories of the ideal case with no parameter errors. This shows that the control method according to this embodiment causes little change in control performance with respect to parameter errors. This result is considered to be due to the fact that the control method according to the present embodiment does not depend on the dynamic characteristic model of the controlled object and has low model dependence. Furthermore, since control law A performs dead time compensation based on a quasi-static model and a dynamic characteristic model of the controlled object, it is considered that the influence of parameter errors was more pronounced. From a comparison between FIGS. 9A and 9B, it can be seen that even in a situation where there is a parameter error, the hand trajectory can be brought closer to the trajectory of the target position _qd by compensating for the influence of the reproducing circuit.

As explained above, according to the control device and control method related to position control of the present embodiment, position control is performed by sliding mode control that is algebraically combined with PID control or PD control, and the dynamic characteristics of the controlled object are Since it has a structure that does not depend on the model, it is less susceptible to the effects of parameter errors, dead time, etc. Therefore, even a hydraulic actuator with a large dead time can be appropriately controlled. Also, since it is based on a quasi-static model of the hydraulic actuator, it can handle the strong nonlinearity of the hydraulic actuator.

Furthermore, the control device and control method according to this embodiment are expanded to compensate for the influence of the reproducing circuit. Therefore, it is also applicable to a hydraulic actuator equipped with a regeneration circuit.

In the above embodiment, the speed sensor 49 is used to measure the expansion and contraction speed of each cylinder 44 to 46, but the invention is not limited to this. For example, the control unit 51 may calculate the speed of each cylinder 44 to 46 based on angle data measured by each angle sensor 481 to 483.

<Embodiment 2>
In Embodiment 1 above, a case has been described in which the position of a controlled object driven by a hydraulic actuator is controlled; however, it is also possible to perform force control of a controlled object using the same control law as in Embodiment 1. . In this embodiment, a control device and a control method for force-controlling a controlled object driven by a hydraulic actuator will be described.

Specifically, the force control device and the force control method will be described using an example in which admittance control is performed on a controlled object driven by the hydraulic actuator 1 similar to the first embodiment. The control system according to the present embodiment has a feedback loop for performing force control, and in order to realize this, the control section 51' includes a reference position calculation section 516 (reference position calculation section). Unlike Embodiment 1, other configurations and the like are the same as in Embodiment 1, so the same reference numerals are given and explanations are omitted.

As shown in the block diagram of FIG. 10, the control system according to the present embodiment uses the measured value of force f _e (hereinafter also referred to as reaction force) applied from the environment to the hydraulic actuator 1 to be controlled, and the hydraulic pressure. The operation of the hydraulic actuator 1 is controlled in admittance by inputting a target applied force _fd , which is a target value of the force that the actuator 1 applies to the environment. The admittance control according to this embodiment is force control based on position control, as shown in FIG. More specifically, in the admittance control according to the present embodiment, the position p of the rod of the hydraulic actuator 1 to be controlled is controlled by the internal position controller that performs position control according to Embodiment 1 to match the target position of the control target. Control is performed to follow the position q of a virtual object having dynamic characteristics. The target dynamic characteristics of the virtual object are dynamic characteristics defined by the target inertia and target viscosity of the controlled object, and the virtual object according to the present embodiment is expressed as a mass damper system that models the dynamic characteristics of the hydraulic actuator 1. be done. In addition, the target applied force f _d and the reaction force f _e measured as the force that the hydraulic actuator 1 receives from the environment due to contact between the controlled object and the highly rigid external environment are acting on the virtual object. Assuming that.

The following describes the control law according to this embodiment, that is, the operation amount u of the hydraulic actuator when a machine driven by a hydraulic actuator is controlled, and force control is performed when the controlled object contacts a highly rigid environment. The control algorithm that determines this will be explained.

<Mathematical preparation>
In this embodiment, a function called a normal cone shown in equation (26) below is used.

<Control law>
The hydraulic actuator to be controlled is expressed by the following formula (27) (formula (27a), formula (27b), formula (27c)).

A force f generated by the actuator, an external force (disturbance) g, and a reaction force f _e from the environment act on the controlled object in the above equation. The set value function Γ is a quasi-static model of the hydraulic actuator similar to Embodiment 1, and is given as a set value function from the current speed v and the manipulated variable u, which is the valve opening command, to the actuator generated force f. It will be done. The control input uεB determines the degree of opening of the flow control valve. The flow control valve opens so that the oil flow inside the hydraulic actuator is generated in the direction of extending the hydraulic actuator when u>0 and in the direction of contracting the hydraulic actuator when u<0. Note that there is no assumption that M is known. It is assumed that p can be obtained by a position sensor.

In this embodiment, the admittance control law shown in each equation (28) below is used.

Here, g^ is the estimated value of the disturbance, and q, B _v and M _v are the position, viscosity and mass of the rod of the virtual object. Equation (28a) represents the dynamic characteristics of the virtual object driven by the target applied force f _d and the measured reaction force f _e from the environment. _The third term on the right side of equation (28a), N _{[-vm, vm]} ⁽ ^q _. It has the effect of limiting the Equations (28b) to (28d) are a position controller that causes the position p of the controlled object to follow the position q of the virtual object, and represent the same control law as the position controller according to the first embodiment. Further, this position controller has PID gains K and B and a time constant H as adjustable parameters.

<Discrete time algorithm>
The algorithm for calculating the control input u _k from the force controller to the hydraulic actuator according to the present embodiment from {f _d,k , f _e,k , p _k , g _k ^} is the same as that in Embodiment 1. It is obtained by following the same discretization procedure as in Equation 29 below.

Here, A=ΔKT+B, k represents a discrete time index, and T represents a sampling interval (the sign of =Δ is as described above).

As shown in equation (29) above, the force control algorithm according to the present embodiment is based on equations (29c) to (29i), which correspond to the position control algorithm of equation (19) according to the first embodiment. , equations (29a) to (29b) for configuring the force controller are added. In this manner, the control device and control method according to the present embodiment performs force control using the internal position controller based on the position control method according to the first embodiment. Therefore, even when the accuracy of prior information on the dynamic characteristics of the controlled object is low or when there is a time delay in the response of the hydraulic actuator, it is possible to obtain high control performance.

<Control system configuration>
As shown in the block diagram of FIG. 11, the control section 51' of the control unit 50' according to the present embodiment has the control section 51' according to the first embodiment, in that it includes a reference position calculation section 516 (reference position calculation section). It is different from part 51.

The reference position calculation unit 516 calculates a reference position using a virtual object that has the dynamic characteristics of a machine that includes a hydraulic actuator to be controlled. Specifically, as shown in the above algorithm, the target applied force set as the target value of the applied force from the hydraulic actuator to the environment and the environment acting on the hydraulic actuator measured by the force sensor 60 included in the hydraulic actuator. The measured value of the reaction force from is input into the model of the virtual object. Then, in the next time step, the control target, more specifically, the reference position where the rod of the hydraulic actuator in the virtual object should be located is calculated. The force sensor 60 that measures the force acting on the hydraulic actuator may be built into the hydraulic actuator, or may be installed outside the hydraulic actuator.

Further, the ideal speed calculation unit 511 according to the present embodiment calculates the ideal speed using the reference position calculated by the reference position calculation unit 516. More specifically, the ideal speed calculation unit 511 calculates the ideal speed by using the reference position as a target position in the algorithm according to the first embodiment. As a result, as shown in FIG. 10, the reference position q, which is the output of the reference position calculation unit 516, is input to the control law according to the first embodiment that operates as an internal position controller, and control is executed. Force control of the controlled object will be performed.

<Control flow>
FIG. 12 is a flowchart showing the flow of force control according to this embodiment. As shown in FIG. 12, in the force control according to the present embodiment, first, a target applied force _fd of the hydraulic actuator is set (step S31). Subsequently, a reference position q is calculated based on the set target applied force f _d and the measured value of the force f _e acting on the hydraulic actuator (step S32). Parameters such as the time constant H given at the start of control are given in advance as in the first embodiment.

More specifically, as a reference position calculation step, the reference position calculation unit 516 of the control unit 51' calculates the reference position at which the rod of the hydraulic actuator to be controlled should be located in the next time step. The algorithm for calculating the reference position is as shown in equations (29a) to (29b) above.

The processing in steps S33 to S36 is similar to the processing in steps S13 to S16 according to the first embodiment (FIG. 5) when the reference position calculated in step S31 is input as the target position.

In steps S33 to S36, the operation amount u is calculated by the internal position controller, and the operation of the hydraulic actuator to be controlled is controlled. The control unit 51' repeats the processes of steps S31 to S37 until the control process is terminated (NO in step S37) due to a termination instruction from the operator, the end of a predetermined operation time, or the like. Further, the control system ends the control process when a predetermined end condition is satisfied, such as an end instruction from the operator, or the end of a predetermined operation time (YES in step S37). Through the above processing, the control unit 51' according to the present embodiment can control the force of the controlled object.

As explained above, in the control device and control method that performs force control according to the present embodiment, the PID control law or PD control law for making the speed of the controlled object follow the reference speed, and the sliding mode control law are simultaneously implemented. Since the force control of the controlled object is performed using the control law according to the first embodiment, which calculates the reference speed and actuator force based on the quasi-static characteristics of the hydraulic actuator, and calculates the operation amount of the hydraulic actuator based on the quasi-static characteristics of the hydraulic actuator. Control can be performed without depending on the dynamic characteristic model of the controlled object. Therefore, even when the accuracy of prior information on the dynamic characteristics of the controlled object is low or when there is a time delay in the response of the hydraulic actuator, it is possible to obtain high control performance.

<Numerical example>
A force control simulation of a hydraulic actuator using the control law according to the present embodiment will be described below. In this example, admittance control according to the present embodiment was performed using a hydraulic testing machine shown in FIG. 13. The hydraulic testing machine is equipped with an electromagnetic proportional flow control valve (the top stage of the modular valve), a relief valve, and a check valve. The flow rate of the hydraulic oil supplied from the pump unit is constant at 4.17×10 ⁻⁴ m ³ /s, and the maximum output of the hydraulic cylinder is 1.56×10 ⁻³ N. Further, the sampling interval is T=0.01s.

The control unit acquires measured values of the rod position p and the reaction force f _e from the environment from the linear encoder and load cell of the hydraulic cylinder. The control input u is converted into an input voltage for the flow control valve by a D/A conversion board.

As shown in FIG. 13, a rubber plate fixed to a rigid wall was used as the environment in which the hydraulic cylinder came into contact. In addition, a metal plate was installed in front of the rubber plate so that only the load button part of the load cell came into contact with the environment. In this example, for comparison, a contact experiment was conducted with three types of rubber plates of different hardness. The hardness of the rubber plates is approximately Shore A hardness 50HS (ShoreA50), Shore A hardness approximately 65HS (ShoreA65), and Shore A hardness approximately 70HS (ShoreA70), and the rubber plate with a smaller number is a softer material.

Each parameter related to the control algorithm of admittance control in this example was set to K=2.5×10 ³ N/m, B=3.0×10 ² N·s/m, and H=0.5 s. The parameters of the virtual object were B _v =7.5×10 ³ N·s/m and M _v =5 kg. These parameters were determined by trial and error so that the generated force f would not become unstable.

14A, 14B, and 14C show the results of contact force control with respect to the stepwise target applied force _fd . As shown in FIGS. 14A, 14B, and 14C, the measured reaction force f can be made to follow the target applied force f _d for all hardness environments.

15A, 15B, and 15C show the results of contact force control for a sinusoidal target applied force _fd . As shown in FIGS. 15A, 15B, and 15C, the measured reaction force f can be made to follow the target applied force f _d for all hardness environments.

As explained above, the force control method according to the present embodiment allows the force applied to the environment from the hydraulic actuator in contact with the highly rigid environment to appropriately follow the target applied force.

The present invention is suitable for position control and force control of machines operated by hydraulic actuators. In particular, it is suitable for automatic positioning control and admittance control of construction machinery operated by hydraulic actuators.

A control device according to a first aspect of the present invention includes an operation command unit that controls a hydraulic actuator that drives a machine to be controlled, and a next time step of the machine based on a target position and a current position of the machine. an ideal speed calculation unit that calculates the ideal speed that should be generated at A reference speed that is a similar speed and a reference generated force that is an actuator force that should be generated when PID control or PD control is performed using the reference speed as a target speed are determined based on the quasi-static characteristics of the hydraulic actuator. the hydraulic actuator, and an operation amount calculation section that calculates the operation amount of the hydraulic actuator based on the quasi-static characteristic of the hydraulic actuator, the reference generated force, and the reference speed.

Further, the hydraulic actuator includes a regeneration circuit, and the ideal speed is based on the target position of the machine, the current position, the opening degree of a flow control valve of the regeneration circuit, and the flow rate of hydraulic fluid passing through the regeneration circuit. It may be calculated based on an estimated value.

Further, the machine is driven by a plurality of the hydraulic actuators, the operation amount calculation section calculates the operation amount for each of the hydraulic actuators, and the operation command section is configured to calculate the operation amount for each of the hydraulic actuators, and the operation command section calculates the operation amount for each of the hydraulic actuators. A predetermined portion of the machine may be moved to a target position by controlling each of the hydraulic actuators based on the hydraulic actuator.

Further, the control device includes an external force estimating section that estimates an external force applied to the machine, and the reference speed calculating section calculates the reference speed and the reference generated force based on the external force estimated by the external force estimating section. It's okay.

Furthermore, the hydraulic actuator may be a hydraulic actuator.

Further, the control device calculates a reaction force that the hydraulic actuator receives from an environment with which the machine comes into contact, and a target applied force that is a target value of the force that the hydraulic actuator applies to the environment, based on the target dynamic characteristics of the machine. a reference position calculation unit that calculates a reference position at which the machine in the virtual object should be positioned at the next time step by inputting the input into a virtual object having The ideal speed may be calculated.

In addition, the control method may be configured to calculate a reaction force that the hydraulic actuator receives from an environment with which the machine comes into contact, and a target applied force that is a target value of the force that the hydraulic actuator applies to the environment, based on a target dynamic characteristic of the machine. a reference position calculation step of calculating a reference position at which the machine in the virtual object should be located at the next time step by inputting the reference position into a virtual object having a The ideal speed may be calculated.

According to the control device and control method of the present invention, the reference speed and actuator force are calculated by simultaneously calculating the PID control law or PD control law for making the speed of the controlled object follow the reference speed and the sliding mode control law, and Since the operation amount of the hydraulic actuator is calculated based on the quasi-static characteristics of the hydraulic actuator, control can be performed without depending on the dynamic characteristic model of the controlled object. Therefore, even when the accuracy of prior information on the dynamic characteristics of the controlled object is low or when there is a time delay in the response of the hydraulic actuator, it is possible to obtain high control performance.

Claims

an operation command unit that controls a hydraulic actuator that drives a machine to be controlled;
an ideal speed calculation unit that calculates an ideal speed to be generated at the next time step of the machine based on a target position and a current position of the machine;
Among the target speeds at which the actuator force that can be generated is calculated when PID control or PD control is performed with the hydraulic actuator, a reference speed that is the speed closest to the ideal speed, and a PID using the reference speed as the target speed. a reference speed calculation unit that calculates a reference generated force that is an actuator force that should be generated when control or PD control is performed based on quasi-static characteristics 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 generated force, and the reference speed;
A control device comprising:
The hydraulic actuator includes a regeneration circuit,
The ideal speed is calculated based on the target position of the machine, the current position, the opening degree of the flow control valve of the regeneration circuit, and an estimated value of the flow rate of the hydraulic fluid passing through the regeneration circuit. Control device as described.
The machine is driven by a plurality of the hydraulic actuators,
The operation amount calculation unit calculates the operation amount for each of the hydraulic actuators,
The control device according to claim 1, wherein the operation command section moves a predetermined part of the machine to a target position by controlling each of the hydraulic actuators based on the calculated operation amount.
further comprising an external force estimation unit that estimates an external force applied to the machine,
The control device according to claim 1, wherein the reference speed calculation unit calculates the reference speed and the reference generated force based on the external force estimated by the external force estimation unit.
The control device according to any one of claims 1 to 4, wherein the hydraulic actuator is a hydraulic actuator.
A reaction force that the hydraulic actuator receives from an environment with which the machine comes into contact and a target applied force that is a target value of the force that the hydraulic actuator applies to the environment are input to a virtual object having target dynamic characteristics of the machine. further comprising a reference position calculation unit that calculates a reference position at which the machine in the virtual object should be located at the next time step,
The control device according to claim 1, wherein the ideal speed calculation unit calculates the ideal speed using the reference position as the target position.
an ideal speed calculation step of calculating an ideal speed to be generated at the next time step of the machine based on a target position and a current position of the machine that is a controlled object driven by a hydraulic actuator;
Among the target speeds at which the actuator force that can be generated is calculated when PID control or PD control is performed with the hydraulic actuator, a reference speed that is the speed closest to the ideal speed, and a PID using the reference speed as the target speed. a reference speed calculation step of calculating a reference generated force, which is an actuator force to be generated when control or PD control is performed, based on quasi-static characteristics of the hydraulic actuator;
an operation amount calculation step of calculating an operation amount of the hydraulic actuator based on the quasi-static characteristic of the hydraulic actuator, the reference generated force, and the reference speed;
control methods including.
A reaction force that the hydraulic actuator receives from an environment with which the machine comes into contact and a target applied force that is a target value of the force that the hydraulic actuator applies to the environment are input to a virtual object having target dynamic characteristics of the machine. further comprising a reference position calculation step of calculating a reference position at which the machine in the virtual object should be located at the next time step;
The control method according to claim 7, wherein in the ideal speed calculation step, the ideal speed is calculated using the reference position as the target position.