Control device, control method, and control program

Abstract

A control device according to the present disclosure acquires a pressure value inside a tube that is connected to a fluid pressure actuator, that is flexible, and that is for supplying and discharging a fluid to and from the fluid pressure actuator. The control device drives the fluid pressure actuator while compensating for deformation of the tube that corresponds to the acquired pressure value. As a result, it is possible to expect appropriate control of the fluid pressure actuator while enhancing the ease of handling.

Description

Control device, control method, and control program

[0001] The present disclosure relates to a control device, a control method, and a control program.

[0002] One type of actuator system is a fluid pressure actuator system configured to transmit power through a tube. For example, Patent Document 1 proposes an actuator system including a driver and a fluid pressure actuator (follower) connected to each other by piping via a conversion unit.

[0003] JP 2021-032379 A JP 2016-061302 A

[0004] Hidaka Asai, et al. “Modeling Inverse Airflow Dynamics Toward Fast Movement Generation Using Pneumatic Artificial Muscle With Long Air Tubes”, [online], [Retrieved May 1, 2025], Internet <URL: https: / / ieeexplore.ieee.org / document / 10547707> Susanne V. Krichel, et al. “Non-linear friction modeling and simulation of long pneumatic transmission lines”, [online], [Retrieved May 1, 2025], Internet <URL: https: / / www.tandfonline.com / doi / full / 10.1080 / 13873954.2013.811268>

[0005] The present inventors have found that conventional systems such as those described in Patent Document 1 have the following problems. Specifically, a fluid pressure actuator is incorporated into the operating part of a robotic device or the like. This allows remote control of the operating part by transmitting power to the fluid pressure actuator via a tube. However, in conventional systems, the tube (piping) is made of a strong material that does not expand in diameter in order to eliminate pumping loss, etc. If a strong material is used for the tube, the tube becomes difficult to displace. As a result, the operating part including the fluid pressure actuator becomes difficult to handle.

[0006] One aspect of the present disclosure has been made in consideration of these points, and an object of the present disclosure is to provide a technique for appropriately controlling a fluid pressure actuator while improving maneuverability.

[0007] In order to solve the above-mentioned problems, the present disclosure employs the following configurations. Note that the following configurations of the invention can be combined as appropriate.

[0008] A control device according to one aspect of the present disclosure includes a control unit configured to acquire a pressure value in a flexible tube connected to a fluid pressure actuator, the tube supplying and discharging fluid to and from the fluid pressure actuator, and drive the fluid pressure actuator while compensating for deformation of the tube in accordance with the acquired pressure value.

[0009] According to this configuration, the use of flexible tubing can improve the maneuverability of the operating parts, including the fluid pressure actuator. However, using a flexible material for the tubing can cause deformation (such as expansion of the diameter) of the tubing when the fluid pressure actuator is driven. This deformation of the tubing can reduce the accuracy of controlling the drive of the fluid pressure actuator. Therefore, this configuration drives the fluid pressure actuator while compensating for the deformation of the tubing. Tube deformation is caused by the pressure inside the tubing. Therefore, the degree of tube deformation can be estimated from the pressure inside the tubing. Therefore, the compensation process compensates for the deformation of the tubing according to the value of the pressure inside the tubing. This allows for appropriate compensation for the deformation of the tubing. As a result, it is possible to suppress a decrease in the accuracy of controlling the fluid pressure actuator due to the deformation of the tubing. Therefore, according to this configuration, it is possible to improve maneuverability and to expect appropriate control of the fluid pressure actuator.

[0010] In the control device according to the above aspect, the tube may connect the fluid pressure actuator and a flow rate measurement unit. The flow rate measurement unit may be provided with a measurement sensor configured to measure an amount of the fluid flowing into the tube from the flow rate measurement unit. The control unit may be further configured to acquire, from the measurement sensor, a measurement value of the amount of the fluid flowing into the tube from the flow rate measurement unit. Driving the fluid pressure actuator may be configured by driving the fluid pressure actuator in accordance with the acquired measurement value.

[0011] The amount of fluid flowing into the tube corresponds to the state (control amount) of the fluid pressure actuator. With this configuration, the state of the fluid pressure actuator can be calculated using a measurement sensor in a flow rate measurement unit that is separate from the fluid pressure actuator. Therefore, the state of the fluid pressure actuator can be identified and the operation of the fluid pressure actuator can be controlled according to the identified state without installing sensors inside or around the fluid pressure actuator. By not installing sensors inside or around the fluid pressure actuator, the fluid pressure actuator can be used in a variety of environments, including environments where the use of sensors is not suitable.

[0012] In the control device according to the above aspect, the flow rate measurement unit may include a mover that drives in response to driving of the mover of the fluid pressure actuator. Driving the fluid pressure actuator while compensating for deformation of the tube may include estimating the position of the mover of the fluid pressure actuator while compensating for deformation of the tube in accordance with the position of the mover of the flow rate measurement unit. With this configuration, it is possible to control the driving of the fluid pressure actuator while estimating the position of the mover of the fluid pressure actuator, without providing sensors inside or around the fluid pressure actuator.

[0013] In the control device according to the above aspect, the fluid may be a liquid. With this configuration, in a situation where a liquid is used as the fluid, it is possible to expect appropriate control of the fluid pressure actuator while improving operability. The liquid may be, for example, water.

[0014] In the control device according to the above aspect, driving the fluid pressure actuator while compensating for deformation of the tube in accordance with the pressure value may be configured by driving the fluid pressure actuator while compensating for deformation of the tube in accordance with the pressure value and the elasticity of gas mixed in the tube. Conventionally, liquids are often treated as incompressible fluids. That is, when a liquid is used as the fluid, the behavior of the fluid transmission line (tube) is handled using HST (Hydrostatic Transmission). However, it is difficult to completely seal the tube, which serves as the transmission line, with liquid. Gas such as air may be mixed into the tube. When gas is mixed in, the fluid in the tube may become compressible due to the elasticity of the mixed gas. Along with tube deformation, this compressibility may cause the behavior of the tube to change compared to when the tube is sealed with liquid. This change may cause errors in the control of the fluid pressure actuator. In contrast, with this configuration, by further compensating for gas elasticity along with tube deformation, more appropriate control of the fluid pressure actuator can be expected.

[0015] In the control device according to the above aspect, the tube may be made of nylon. Nylon tubes are inexpensive but easily deformed. Deformation of the nylon tube may result in a significant decrease in the accuracy of controlling the drive of the fluid pressure actuator. In contrast, with this configuration, when driving the fluid pressure actuator, the tube deformation is compensated for in accordance with the pressure value within the tube, thereby preventing this decrease in accuracy. Therefore, with this configuration, it is possible to improve maneuverability and reduce the manufacturing cost of an actuator system that can appropriately control the fluid pressure actuator. In other words, the configuration of the present disclosure that compensates for tube deformation can be particularly beneficial in situations where nylon tubes are used.

[0016] In the control device according to the above aspect, the diameter of the tube may be 3 mm or less, and the length of the tube may be 20 m or more. A long, thin tube with a diameter of 3 mm or less and a length of 20 m or more is easy to handle but is easily deformed. Deformation of the long, thin tube may significantly reduce the accuracy of controlling the drive of the fluid pressure actuator. In contrast, this configuration can mitigate this reduction in accuracy by compensating for tube deformation in accordance with the pressure value within the tube when driving the fluid pressure actuator. Therefore, this configuration can further improve handleability by using a long, thin tube, and can be expected to ensure appropriate control of the fluid pressure actuator. In other words, the configuration of the present disclosure, which compensates for tube deformation, can be particularly beneficial even in situations where a long, thin tube is used.

[0017] Note that the embodiments of the present disclosure may not be limited to the above-described control device (information processing device). As another aspect of the control device according to each of the above aspects, one aspect of the present disclosure may be an information processing method that realizes all or part of each of the above configurations, or may be a program, or may be a storage medium readable by a machine such as a computer that stores such a program. A storage medium readable by a machine such as a computer is a medium that stores information such as a program by electrical, magnetic, optical, mechanical, or chemical action.

[0018] For example, a control method according to an aspect of the present disclosure may be an information processing method executed by a computer, and may include acquiring a pressure value in a flexible tube connected to a fluid pressure actuator and supplying and discharging fluid to the fluid pressure actuator, and driving the fluid pressure actuator while compensating for deformation of the tube in accordance with the acquired pressure value.

[0019] Furthermore, for example, a control program according to an aspect of the present disclosure may be a program for causing a computer to execute a control method (information processing method) that may include acquiring a pressure value in a flexible tube connected to a fluid pressure actuator and supplying and discharging fluid to and from the fluid pressure actuator, and driving the fluid pressure actuator while compensating for deformation of the tube in accordance with the acquired pressure value.

[0020] According to the present disclosure, it is possible to expect appropriate control of the fluid pressure actuator while improving the ease of handling.

[0021] FIG. 1 schematically shows an example of a situation to which the present disclosure is applied. FIG. 2A schematically shows an example of a method for measuring a current value of a controlled variable of a fluid pressure actuator. FIG. 2B schematically shows an example of a method for estimating the position of a mover of a fluid pressure actuator. FIG. 3 schematically shows an example of an actuator system. FIG. 4 schematically shows another example of an actuator system. FIG. 5 schematically shows another example of an actuator system. FIG. 6 schematically shows another example of an actuator system. FIG. 7 schematically shows another example of an actuator system. FIG. 8 schematically shows an example of a control scheme. FIG. 9 schematically shows an example of the hardware configuration of a control device. A flowchart showing an example of a processing procedure of the control device. FIG. 10 schematically shows an example of the software configuration of the control device. FIG. 11 is a flowchart showing an example of a processing procedure of the control device. FIG. 12A schematically shows an example of a situation in which a load acts on a mover of a fluid pressure actuator. FIG. 12B schematically shows another example of a situation in which a load acts on a mover of a fluid pressure actuator. FIG. 13A is a diagram illustrating the characteristics of the load acting in the situation of FIG. 12A. FIG. 13B is a diagram illustrating the characteristics of the load acting in the situation of FIG. 12B. FIG. 14 schematically illustrates another example of a control scheme. FIG. 15 schematically illustrates the configuration of the system used in the first experimental example. FIG. 16 illustrates the results of the first experimental example. FIG. 17A illustrates the control results of the comparative example. FIG. 17B illustrates the control results (error) of the comparative example. FIG. 18A illustrates the control results of the example. FIG. 18B illustrates the control results (error) of the example. FIG. 19 illustrates the measured values ​​and model-estimated values ​​for each condition in the third experimental example. FIG. 20A illustrates the actual measured values ​​and estimated values ​​of the position of the mover of the fluid pressure actuator in the fourth experimental example. FIG. 20B illustrates the actual measured values ​​of the pressure inside the tube in the fourth experimental example.

[0022] An embodiment according to one aspect of the present invention (hereinafter also referred to as "the present embodiment") will be described below with reference to the drawings. However, the present embodiment described below is merely an example of the present invention in all respects. Needless to say, various improvements and modifications can be made without departing from the scope of the present invention. In other words, when implementing the present invention, specific configurations according to the embodiment may be appropriately adopted. Note that, although data appearing in the present embodiment are described in natural language, more specifically, they are specified using pseudo-language, commands, parameters, machine language, etc. that can be recognized by a computer.

[0023] §1 Application Example Fig. 1 shows a schematic diagram of an example of a situation in which the present disclosure is applied. A drive system S according to this embodiment includes an actuator system AS and a control device 1.

[0024] In this embodiment, the actuator system AS includes a fluid pressure actuator 2, a drive unit 3, and a tube 4. The fluid pressure actuator 2 is configured to convert the pressure of a fluid contained therein into a drive force and output the obtained drive force to an object to be driven. The drive unit 3 is configured to drive the fluid pressure actuator 2 by causing the supply and discharge of fluid to and from the fluid pressure actuator 2. The tube 4 is connected to the fluid pressure actuator 2. The tube 4 is flexible. The tube 4 is configured to supply and discharge fluid to and from the fluid pressure actuator 2.

[0025] 1, the tube 4 may be configured to be directly connected to the drive unit 3, thereby directly communicating between the drive unit 3 and the fluid pressure actuator 2. In another example, as illustrated in Fig. 2A described below, the tube 4 may be configured to be indirectly connected to the drive unit 3, thereby indirectly communicating between the drive unit 3 and the fluid pressure actuator 2.

[0026] The control device 1 is one or more computers configured to control the operation of the fluid pressure actuator 2. In this embodiment, the control device 1 acquires a pressure value (also referred to as a "pressure value") 125 inside the tube 4. The control device 1 then drives the fluid pressure actuator 2 while compensating for deformation of the tube 4 according to the acquired pressure value 125.

[0027] According to this embodiment, the use of a flexible tube 4 improves the maneuverability of the operating parts, including the fluid pressure actuator 2. However, using a flexible tube 4 may cause deformation of the tube 4 when the fluid pressure actuator 2 is driven. The deformation of the tube 4 may include, for example, expansion or contraction of the diameter. When a flexible tube 4 is used, the deformation of the tube 4 may cause the amount of fluid flowing into or out of the fluid pressure actuator 2 to differ compared to when a non-deformable tube is used. Therefore, the deformation of the tube 4 may result in a decrease in the accuracy of controlling the drive of the fluid pressure actuator 2. In contrast, in this embodiment, the control device 1 controls the drive of the fluid pressure actuator 2 while compensating for the deformation of the tube 4. The deformation of the tube 4 is caused by the pressure inside the tube 4. Therefore, the degree of deformation of the tube 4 can be estimated from the pressure inside the tube 4. Therefore, in the compensation process, the control device 1 compensates for the deformation of the tube 4 according to the pressure value 125 inside the tube 4. This allows the control device 1 to appropriately compensate for the deformation of the tube 4 when controlling the drive of the fluid pressure actuator 2. As a result, it is possible to suppress a decrease in the control accuracy of the fluid pressure actuator 2 caused by deformation of the tube 4. Therefore, according to this embodiment, it is possible to improve the operability and to expect appropriate control of the fluid pressure actuator 2.

[0028] [Fluid Pressure Actuator] The type of the fluid pressure actuator 2 is not particularly limited and may be selected appropriately depending on the embodiment as long as it is connected to the tube 4 and configured to convert a fluid into a driving force. The fluid pressure actuator 2 may include, for example, a fluid pressure cylinder, a fluid pressure artificial muscle, etc. The fluid pressure artificial muscle may include a pneumatic artificial muscle. The drive type of the fluid pressure actuator 2 is also not particularly limited and may be selected appropriately depending on the embodiment. The drive type of the fluid pressure actuator 2 may be selected appropriately from, for example, a linear type, a rotary type, etc.

[0029] The fluid may be a liquid or a gas. The liquid may be, for example, water, oil, etc. The gas may be, for example, air, etc. In this case, in situations where a liquid or gas is used as the fluid, improved maneuverability and appropriate control of the fluid pressure actuator 2 can be expected. In one example, the fluid may be water. That is, the tube 4 and the fluid pressure actuator 2 may be configured to store water therein as the fluid for transmitting power. According to one example of this embodiment, in situations where water is used as the fluid, improved maneuverability and appropriate control of the fluid pressure actuator 2 can be expected.

[0030] The driving force output from the fluid pressure actuator 2 may be used as appropriate depending on the embodiment. The type of object to be driven to which the driving force is applied is not particularly limited and may be selected as appropriate depending on the embodiment. In a typical example, the fluid pressure actuator 2 may be incorporated into a robotic device, and the driving force of the fluid pressure actuator 2 may be used to drive the robotic device. By remotely driving the fluid pressure actuator 2 via the tube 4, the robotic device can be remotely controlled.

[0031] [Tube] Any flexible material may be selected as the material for the tube 4. In one example, the tube 4 may be made of nylon. Nylon tubes are inexpensive but easily deformed. Nylon tubes are particularly prone to deformation when a liquid (such as water or oil) is used as the fluid. Therefore, when a nylon tube is used as the tube 4, deformation of the nylon tube may significantly reduce the accuracy of controlling the drive of the fluid pressure actuator 2. In contrast, in this embodiment, the control device 1 compensates for the deformation of the tube 4 in accordance with the pressure value 125 within the tube 4 when driving the fluid pressure actuator 2, thereby suppressing this reduction in accuracy. Therefore, according to one example of this embodiment, it is possible to improve the operability and reduce the manufacturing cost of the actuator system AS, which can appropriately control the fluid pressure actuator 2. In other words, the configuration of this embodiment, which compensates for the deformation of the tube 4, is particularly beneficial when a nylon tube is used as the tube 4.

[0032] In another example, the tube 4 may be made of PEEK (PolyEtherEtherKetone) resin. Deformation of a tube made of PEEK resin is easy to predict and model. Therefore, according to one example of the present embodiment, by using a tube made of PEEK resin as the tube 4, it is possible to improve the accuracy of compensating for deformation of the tube 4, and as a result, it is possible to expect an improvement in the control accuracy of the fluid pressure actuator 2.

[0033] In yet another example, the tube 4 may be a hose made of a composite material (composite material hose). For example, the tube 4 may be a hose with improved properties (flexibility, chemical resistance, pressure resistance, etc.) by layering materials such as resin film, tubing, and cloth in multiple layers and reinforcing the inside and outside with spirally wound wire. This allows the pressure supplied to the fluid pressure actuator 2 to be increased. Furthermore, since the resistance of the tube 4 in harsh environments is improved, beneficial effects can be expected when the fluid pressure actuator 2 is used in applications that generate large forces in harsh environments. When the tube 4 includes wire reinforcement, the model of a fluid pressure artificial muscle shown in Non-Patent Document 1 may be used to determine the deformation (expansion or contraction) of the tube 4.

[0034] The deformation of the tube 4 may be constituted by deformation (expansion or contraction) in at least one of the radial and longitudinal directions of the tube 4. When the tube 4 includes wire reinforcement, deformation in the longitudinal direction is more likely to occur. Therefore, in one example, when the tube 4 includes wire reinforcement, it is desirable that the deformation of the tube 4 be constituted by deformation in the radial and longitudinal directions. On the other hand, when the tube 4 does not include wire reinforcement, it is desirable that the deformation of the tube 4 be constituted only by deformation in the radial direction.

[0035] Furthermore, the dimensions of the tube 4 are not particularly limited and may be determined appropriately depending on the embodiment. For example, the diameter of the tube 4 may be 3 mm or less, and the length of the tube 4 may be 20 m or more. A long, thin tube with a diameter of 3 mm or less and a length of 20 m or more is easy to handle but is easily deformed. In particular, when a liquid (water, oil, etc.) is used as the fluid, a long, thin tube is easily deformed. Therefore, when a long, thin tube is used as the tube 4, deformation of the long, thin tube may significantly reduce the accuracy of controlling the drive of the fluid pressure actuator 2. In contrast, in this embodiment, the control device 1 compensates for the deformation of the tube 4 in accordance with the pressure value 125 within the tube 4 when driving the fluid pressure actuator 2, thereby suppressing this reduction in accuracy. Therefore, according to one example of this embodiment, using a long, thin tube as the tube 4 further improves handleability and can be expected to appropriately control the fluid pressure actuator 2. That is, the configuration of this embodiment that compensates for deformation of the tube 4 can be particularly beneficial when a long, thin tube having a diameter of 3 mm or less and a length of 20 m or more is used as the tube 4. However, the dimensions of the tube 4 are not limited to this example. In another example, the diameter of the tube 4 may be greater than 3 mm. In yet another example, the length of the tube 4 may be less than 20 m. The diameter of the tube 4 may be the internal diameter (inner diameter) of the tube 4.

[0036] [Method of Acquiring Various Information] The method of measuring the pressure value 125 inside the tube 4 is not particularly limited and may be selected appropriately depending on the embodiment. In a typical example, a pressure gauge may be used to measure the pressure value 125. The pressure gauge may be placed at any location where the pressure inside the tube 4 can be measured. The control device 1 may acquire the value 125 directly or indirectly from the pressure gauge.

[0037] Any information other than the pressure value 125 may be used to control the fluid pressure actuator 2. In a typical example, the operation of the fluid pressure actuator 2 may be controlled according to the deviation between a current value and a target value of a controlled variable. The controlled variable of the fluid pressure actuator 2 may be selected appropriately depending on the embodiment. When a fluid pressure cylinder is used as the fluid pressure actuator 2, the controlled variable of the fluid pressure actuator 2 may be, for example, the position of the piston, the driving force of the piston, etc.

[0038] The target value may be determined as appropriate for any purpose, such as being a constant value or conforming to a predetermined condition. On the other hand, the current value of the controlled variable may be measured by any method. For example, the fluid pressure actuator 2 may be equipped with a sensor, and the current value of the controlled variable of the fluid pressure actuator 2 may be measured by this sensor.

[0039] Furthermore, in this embodiment, since the tube 4 is directly connected to the fluid pressure actuator 2, the fluid flowing into the tube 4 is supplied to the fluid pressure actuator 2 almost as is. The fluid discharged from the fluid pressure actuator 2 flows out almost as is to the drive unit 3 side via the tube 4. Therefore, the amount of fluid flowing into the tube 4 and the amount of fluid flowing out from the tube 4 correspond to the control variable of the fluid pressure actuator 2. Therefore, in another example, the amount of fluid flowing into the tube 4 (the amount of fluid flowing out from the tube 4) may be measured, and the current value of the control variable of the fluid pressure actuator 2 may be estimated from the measured value of the fluid inflow (outflow) amount. In other words, the current value of the control variable of the fluid pressure actuator 2 may be measured indirectly via the amount of fluid flowing into the tube 4 (the amount of fluid flowing out from the tube 4). Note that a negative amount of fluid flowing into the tube 4 is a positive amount of fluid flowing out from the tube 4. Therefore, the amount of fluid flowing into the tube 4 may be treated as synonymous with the amount of fluid flowing out from the tube 4.

[0040] (Measurement Method) Fig. 2A schematically shows an example of a method for measuring a current value of a controlled variable of the fluid pressure actuator 2 according to this embodiment. In the example of Fig. 2A, the actuator system AS may further include a flow rate measuring unit 5 disposed between the drive unit 3 and the fluid pressure actuator 2. The drive unit 3 may be appropriately connected to the flow rate measuring unit 5 via piping or the like. The tube 4 may connect the fluid pressure actuator 2 and the flow rate measuring unit 5. The tube 4 may be configured to connect the internal spaces of the fluid pressure actuator 2 and the flow rate measuring unit 5, thereby connecting the fluid pressure actuator 2 and the flow rate measuring unit 5. The internal spaces of the flow rate measuring unit 5, the tube 4, and the fluid pressure actuator 2 may be sealed.

[0041] The flow rate measurement unit 5 may be provided with a measurement sensor 5S configured to measure the amount of fluid flowing from the flow rate measurement unit 5 into the tube 4. As long as the amount of fluid flowing into the tube 4 can be measured, the type of measurement sensor 5S is not particularly limited and may be selected appropriately depending on the embodiment. As long as the amount of fluid flowing into the tube 4 can be measured by the measurement sensor 5S, the configuration of the flow rate measurement unit 5 is not particularly limited and may be determined appropriately depending on the embodiment. The flow rate measurement unit 5 may be configured to be driven in conjunction with the fluid pressure actuator 2. As a result, the amount of fluid flowing from the flow rate measurement unit 5 into the tube 4 may correspond to the control amount of the fluid pressure actuator 2. For example, the flow rate measurement unit 5 may be configured by an actuator of the same type as or a different type from the fluid pressure actuator 2.

[0042] The control device 1 may acquire a measured value 127 of the amount of fluid flowing into the tube 4 from the flow rate measurement unit 5 from the measurement sensor 5S. Driving the fluid pressure actuator 2 may be configured by driving the fluid pressure actuator 2 in accordance with the acquired measured value 127. In one example, the control device 1 may drive the fluid pressure actuator 2 in accordance with the deviation between a target value of the controlled variable of the fluid pressure actuator 2 and a current value of the controlled variable estimated from the acquired measured value 127. This driving of the fluid pressure actuator 2 may be performed using feedforward or feedback control.

[0043] According to one example of the present embodiment, the state of the fluid pressure actuator 2 (the current value of the controlled variable) can be identified by the measurement sensor 5S of the flow rate measurement unit 5 that is separated from the fluid pressure actuator 2. Therefore, the state of the fluid pressure actuator 2 can be identified and the drive of the fluid pressure actuator 2 can be controlled in accordance with the identified state without providing a sensor inside or around the fluid pressure actuator 2. By not providing a sensor inside or around the fluid pressure actuator 2, the fluid pressure actuator 2 can be used in various environments, including environments in which the use of sensors is not suitable. For example, the fluid pressure actuator 2 can be used to drive a robot device in environments such as places with high levels of radiation, places with high levels of dust, and underwater.

[0044] The method for measuring the amount of fluid flowing into the tube 4 is not limited to this example and may be modified as appropriate depending on the embodiment. In another example, instead of the flow measurement unit 5, a flow meter may be used to measure the amount of fluid flowing into the tube 4. The flow meter may be disposed at any position where the amount of fluid flowing into the tube 4 can be measured. For example, the flow meter may be disposed at the end of the tube 4 on the drive unit 3 side. In this example of the present embodiment, the state of the fluid pressure actuator 2 can be identified by using a flow meter without providing a sensor inside or around the fluid pressure actuator 2. Therefore, by not providing a sensor inside or around the fluid pressure actuator 2, the fluid pressure actuator 2 can be used in various environments, including environments where the use of sensors is not suitable. Even in harsh environments where the use of sensors is not suitable, the environment around the operating parts, including the fluid pressure actuator 2, may be observed using an available sensor, such as a camera.

[0045] (Position Estimation Method) FIG. 2B schematically shows an example of a method for estimating the position of the mover 2M of the fluid pressure actuator 2 according to this embodiment. In one example, the flow rate measurement unit 5 may include a mover 5M that is driven in response to driving of the mover 2M of the fluid pressure actuator 2. Accordingly, driving the fluid pressure actuator 2 while compensating for deformation of the tube 4 may include estimating the position of the mover 2M of the fluid pressure actuator 2 while compensating for deformation of the tube 4 in accordance with the position of the mover 5M of the flow rate measurement unit 5. An example of the estimation method will be described later ( FIG. 8 ). According to this example of the present embodiment, it is possible to control the driving of the fluid pressure actuator 2 while estimating the position of the mover 2M of the fluid pressure actuator 2, even without providing sensors inside or around the fluid pressure actuator 2.

[0046] The mover 2M may be a mechanical element that is driven when power is applied. The specific configuration of the mover 2M may be determined appropriately depending on the type of fluid pressure actuator 2. The mover 2M may be, for example, a piston and shaft of a fluid pressure cylinder, or the operating end of a fluid pressure artificial muscle. The mover 5M of the flow rate measurement unit 5 may also be similar to the mover 2M of the fluid pressure actuator 2. In one example, the flow rate measurement unit 5 may be configured by an actuator of the same type as or a different type from the fluid pressure actuator 2. The mover of the actuator may constitute the mover 5M of the flow rate measurement unit 5.

[0047] Driving the mover 5M of the flow rate measuring unit 5 in response to driving of the mover 2M of the fluid pressure actuator 2 may mean that the mover 5M behaves in conjunction with the mover 2M. In one example, the drive amount of the mover 5M of the flow rate measuring unit 5 may match the drive amount of the mover 2M of the fluid pressure actuator 2. However, as long as the mover 5M can behave in conjunction with the mover 2M, the drive amount of the mover 5M of the flow rate measuring unit 5 does not necessarily have to match the drive amount of the mover 2M of the fluid pressure actuator 2. The correspondence relationship between the drive amounts of the mover 2M of the fluid pressure actuator 2 and the mover 5M of the flow rate measuring unit 5 may be determined appropriately depending on the dimensions of the actuators used for each (for example, S in FIG. 8 to be described later). Ｏｐ / SＡｃｔ In one example, the correspondence between the drive amounts of the respective movers (2M, 5M) may be expressed by a linear or nonlinear model.

[0048] In addition, in one example, the mover 2M of the fluid pressure actuator 2 may be connected to an element such as a joint or link of any robotic device. As a result, the robotic device may be driven in response to the driving of the mover 2M. In this case, estimating the position of the mover 2M of the fluid pressure actuator 2 may include estimating the state (position, posture, etc.) of the element connected to the mover 2M. The state of the element of the robotic device may be appropriately estimated from the position of the mover 2M. For example, the correspondence between the position of the mover 2M and the state of the element of the robotic device may be appropriately modeled in accordance with the attributes of the mover 2M (movable range, dimensions, etc.), the attributes of the element (movable range, dimensions, etc.), and the connection state, such as the connection form between the mover 2M and the element. The state of the element of the robotic device may be appropriately estimated from the position (estimated value) of the mover 2M using the obtained model.

[0049] [Configuration Example of Actuator System] In this embodiment, the actuator system AS includes a flexible tube 4 and a fluid pressure actuator 2. The tube 4 is connected to the fluid pressure actuator 2 and is configured to supply (inflow) and discharge (outflow) fluid to the fluid pressure actuator 2. As long as the actuator system AS is configured in this manner, the configuration of the actuator system AS is not particularly limited and may be selected appropriately depending on the embodiment.

[0050] Fig. 3 schematically shows an example of the configuration of an actuator system AS1 according to this embodiment. In the example of Fig. 3, the actuator system AS1 includes a drive section 30, a flow rate measurement unit 51, a tube 41, and a fluid pressure actuator 20. The actuator system AS1 is an example of an actuator system AS. The drive section 30 is an example of a drive section 3. The flow rate measurement unit 51 is an example of a flow rate measurement unit 5. The tube 41 is an example of a tube 4. The fluid pressure actuator 20 is an example of a fluid pressure actuator 2.

[0051] The driving unit 30 includes a fluid source 301, a pump 302, a first valve 303, a second valve 304, a first pipe 305, and a second pipe 306. The fluid source 301 is configured to supply a fluid to the first pipe 305 and to receive the fluid discharged from the second pipe 306. The fluid may be a liquid or a gas. The fluid source 301 may be configured appropriately depending on the type of fluid used. For example, if the fluid is water, the fluid source 301 may be a water tank. If the fluid is oil, the fluid source 301 may be an oil tank.

[0052] The pump 302 is configured to draw fluid from the fluid source 301 into the first pipe 305. The first pipe 305 forms a path for supplying fluid from the fluid source 301 to the flow rate measurement unit 51 (second internal space 5102). The first valve 303 is configured to open and close the path of the first pipe 305. The second pipe 306 forms a path for discharging fluid from the flow rate measurement unit 51 to the fluid source 301. The second valve 304 is configured to open and close the path of the second pipe 306.

[0053] The flow rate measuring unit 51 is composed of a fluid pressure cylinder 510. Specifically, the flow rate measuring unit 51 includes the fluid pressure cylinder 510, a scale 511, and a measurement sensor 512. The fluid pressure cylinder 510 includes a cylinder tube 5100, a piston 5103, and a shaft (rod) 5104. The cylinder tube 5100 forms a housing that houses the fluid. The cylinder tube 5100 is an example of a stator of the fluid pressure cylinder 510. The piston 5103 and the shaft 5104 are an example of a mover of the fluid pressure cylinder 510, and an example of a mover 5M of the flow rate measuring unit 5.

[0054] The piston 5103 is disposed inside the cylinder tube 5100 and divides the internal space of the cylinder tube 5100 into two internal spaces (5101, 5102). The shaft 5104 has an axis. The shaft 5104 extends from the piston 5103 in one axial direction (leftward in the figure) and protrudes to the outside of the cylinder tube 5100. As a result, the mover (piston 5103 and shaft 5104) is disposed so as to be in contact with the internal spaces (5101, 5102) of the cylinder tube 5100 and is configured to obtain a driving force in response to the pressure of the fluid in the internal spaces (5101, 5102).

[0055] The first internal space 5101 is located on the opposite side of the piston 5103 from the direction in which the shaft 5104 extends. On the other hand, the second internal space 5102 is located on the side of the piston 5103 in the direction in which the shaft 5104 extends. When the first internal space 5101 is filled with fluid and the fluid is discharged from the second internal space 5102, the piston 5103 and the shaft 5104 move forward (moving leftward in the figure). On the other hand, when the fluid is discharged from the first internal space 5101 and the second internal space 5102 is filled with fluid, the piston 5103 and the shaft 5104 move backward (moving rightward in the figure). Note that, for convenience of explanation, hereinafter, movement in the direction in which the shaft extends will be referred to as "moving forward," and movement in the opposite direction to the direction in which the shaft extends will be referred to as "moving backward."

[0056] 3 , the fluid pressure actuator 20 is configured by a fluid pressure cylinder of the same type as the flow rate measuring unit 51. Specifically, the fluid pressure actuator 20 includes a cylinder tube 200, a piston 203, and a shaft 204. The piston 203 and the shaft 204 are an example of a mover 2M of the fluid pressure actuator 2. The cylinder tube 200, the piston 203, and the shaft 204 may be configured in the same manner as the cylinder tube 5100, the piston 5103, and the shaft 5104 of the fluid pressure cylinder 510. The first internal space 201 and the second internal space 202 of the cylinder tube 200 may be configured in the same manner as the first internal space 5101 and the second internal space 5102 of the cylinder tube 5100.

[0057] The tube 41 may connect the fluid pressure actuator 20 and the flow rate measuring unit 51 (fluid pressure cylinder 510) so as to connect internal spaces on the same side of the fluid pressure actuator 20 and the flow rate measuring unit 51. In the example shown in FIG. 3 , the tube 41 connects first internal spaces (201, 5101) of the fluid pressure actuator 20 and the flow rate measuring unit 51 to each other. The first internal spaces (201, 5101) of the fluid pressure actuator 20 and the flow rate measuring unit 51 and the tube 41 may be filled with fluid and then sealed. A pressure gauge 411 may be provided in the tube 41. The pressure gauge 411 may measure a pressure value 125 in the tube 41. The pressure gauge 411 may be arranged at any location on the tube 41. In one example, as shown in FIG. 3 , the pressure gauge 411 may be arranged on the inlet side of the tube 41 (the end connected to the flow rate measuring unit 51). On the other hand, each pipe (305, 306) of the drive unit 30 may be connected to the internal space of the flow rate measurement unit 51 on the side opposite to the side connected to the tube 41. In the example of FIG. 3 , each pipe (305, 306) of the drive unit 30 is connected to a second internal space 5102 of the flow rate measurement unit 51.

[0058] The fluid used between the drive unit 30 and the flow rate measurement unit 51 and the fluid used between the flow rate measurement unit 51 and the fluid pressure actuator 20 may be the same or different. The type of fluid used in each unit is not particularly limited and may be selected appropriately depending on the embodiment. In one example, water may be used as the fluid both between the drive unit 30 and the flow rate measurement unit 51 and between the flow rate measurement unit 51 and the fluid pressure actuator 20. In another example, oil may be used as the fluid between the drive unit 30 and the flow rate measurement unit 51, and water may be used as the fluid between the flow rate measurement unit 51 and the fluid pressure actuator 20.

[0059] In this actuator system AS1, by operating the pump 302, opening the first valve 303, and closing the second valve 304, fluid can be supplied from the fluid source 301 to the second internal space 5102 of the flow rate measuring unit 51. By supplying fluid to the second internal space 5102 of the flow rate measuring unit 51, the piston 5103 can be moved backward (to the right in the figure). The first internal spaces (201, 5101) of the fluid pressure actuator 20 and the flow rate measuring unit 51, and the tube 41 are filled with fluid and then sealed. Therefore, when the piston 5103 moves backward, fluid is discharged from the first internal space 5101 of the flow rate measuring unit 51 to the tube 41. In other words, fluid flows from the first internal space 5101 of the flow rate measuring unit 51 into the tube 41. In response to this, fluid is supplied from the tube 41 to the first internal space 201 of the fluid pressure actuator 20. When fluid is supplied to the first internal space 201 of the fluid pressure actuator 20, the piston 203 and the shaft 204 of the fluid pressure actuator 20 are driven forward (to the right in the drawing).

[0060] On the other hand, by closing the first valve 303 and opening the second valve 304, it is possible to discharge fluid from the second internal space 5102 of the flow rate measuring unit 51 to the fluid source 301. Discharging fluid from the second internal space 5102 of the flow rate measuring unit 51 allows the piston 5103 to move forward (toward the left in the figure). When the piston 5103 moves forward, fluid is drawn from the tube 41 into the first internal space 5101 of the flow rate measuring unit 51. That is, fluid flows out from the tube 41 into the first internal space 5101 of the flow rate measuring unit 51. In response to this, fluid is discharged from the first internal space 201 of the fluid pressure actuator 20 to the tube 41. When fluid is discharged from the first internal space 201 of the fluid pressure actuator 20, the piston 203 and shaft 204 of the fluid pressure actuator 20 are driven in the backward direction (toward the left in the figure). The series of drive operations in the forward and backward directions described above is one example of an operation in which the mover 5M of the flow rate measuring unit 5 is driven in response to the drive of the mover 2M of the fluid pressure actuator 2. Note that by opening both the first valve 303 and the second valve 304, it is possible to stop the piston 203 and the shaft 204 of the fluid pressure actuator 20. Also, by closing both the first valve 303 and the second valve 304, it is possible to fix the piston 203 and the shaft 204 of the fluid pressure actuator 20.

[0061] Therefore, in the actuator system AS1, the amount of drive of the piston 5103 and shaft 5104 of the flow rate measurement unit 51 (fluid pressure cylinder 510) corresponds to the amount of fluid flowing into the tube 41. That is, the amount of fluid flowing into the tube 41 can be measured via the amount of drive of the piston 5103 and shaft 5104. The position of the piston 5103 of the flow rate measurement unit 51 corresponds to the position of the piston 203 of the fluid pressure actuator 20. Therefore, the scale 511 is disposed on the portion of the shaft 5104 that protrudes from the cylinder tube 5100. The measurement sensor 512 is configured to measure the amount of fluid flowing from the flow rate measurement unit 51 into the tube 41 via the amount of drive of the piston 5103 and shaft 5104 by reading the scale 511. The measurement sensor 512 is an example of a measurement sensor 5S. The type of the measurement sensor 512 is not particularly limited and may be selected appropriately depending on the embodiment. In a typical example, an optical encoder may be used for the measurement sensor 512.

[0062] The control device 1 may be directly or indirectly connected to each valve (303, 304). By controlling the opening and closing of each valve (303, 304), it is possible to control the driving of the fluid pressure actuator 20 via the flow rate measurement unit 51. The control device 1 may also be directly or indirectly connected to a pressure gauge 411, and may acquire a value 125 of the pressure inside the tube 41 from the pressure gauge 411. The control device 1 may also be directly or indirectly connected to a measurement sensor 512, and may acquire a measurement value 127 of the amount of fluid inflow into the tube 41 from the flow rate measurement unit 51, from the measurement sensor 512.

[0063] It should be noted that, with regard to the configuration of the actuator system AS1, it is possible to omit, replace, or add components as appropriate depending on the embodiment. For example, in the example shown in Fig. 3, the fluid pressure actuator 20 is configured as a single-acting type. However, the configuration of the fluid pressure actuator 20 is not limited to this example. In another example, the fluid pressure actuator 20 may be configured as a double-acting type.

[0064] In another example, the flow rate measurement unit 51 may be omitted. In another example, the actuator system AS1 may include a flow meter instead of the flow rate measurement unit 51. As an example of this case, the tube 41 may be connected to an end of each pipe (305, 306) of the drive unit 30. The flow meter may be disposed at or near an inlet from each pipe (305, 306) to the tube 41. In yet another example, the actuator system AS1 may include a measurement sensor provided in the fluid pressure actuator 20 instead of the flow rate measurement unit 51. As a result, the control amount of the fluid pressure actuator 20 may be directly measured by the measurement sensor.

[0065] In addition, in the example of FIG. 3 , the actuator system AS1 is configured to be able to control the drive of the fluid pressure actuator 20 via the flow rate measurement unit 51 by controlling the opening and closing of each valve (303, 304). However, the method of controlling the drive of the fluid pressure actuator 20 is not limited to this example and may be changed as appropriate depending on the embodiment. In another example, the actuator system AS1 may further include a master actuator having a configuration similar to that of the fluid pressure actuator 20. The master actuator may be connected to the flow rate measurement unit 51 in the same manner as the fluid pressure actuator 20. Accordingly, the actuator system AS1 may be configured to be able to control the drive of the fluid pressure actuator 20 via the drive of the master actuator. The master actuator may be driven manually by an operator.

[0066] 3, the same type of actuator (fluid pressure cylinder) is used for the flow rate measurement unit 51 and the fluid pressure actuator 20. However, the relationship between the flow rate measurement unit 51 and the fluid pressure actuator 20 is not limited to this example. The flow rate measurement unit 51 may be configured with an actuator of a different type from the fluid pressure actuator 20. In another example, an actuator other than a fluid pressure cylinder may be used for at least one of the flow rate measurement unit 51 and the fluid pressure actuator 20.

[0067] In another example, the shaft 5104 of the flow rate measurement unit 51 may be configured to extend in both directions, rather than in one direction. That is, the shaft 5104 may be configured to protrude from the interior of the cylinder tube 5100 on both sides in the axial direction (left and right direction in the figure). As a result, the flow rate measurement unit 51 (fluid pressure cylinder 510) may be configured so that the internal spaces (5101, 5102) are not distinguished. The same may be true for the fluid pressure actuator 20. That is, the shaft 204 of the fluid pressure actuator 20 may be configured so that the shaft 204 protrudes from the interior of the cylinder tube 200 on both sides in the axial direction. As a result, the fluid pressure actuator 20 may be configured so that the internal spaces (201, 202) are not distinguished.

[0068] (Double-acting) Fig. 4 schematically shows an example of the configuration of an actuator system AS2 according to this embodiment. In the example of Fig. 4, the actuator system AS2 includes a drive section 31, a (first) flow rate measurement unit 51, a (second) flow rate measurement unit 52, a (first) tube 41, a (second) tube 42, and a fluid pressure actuator 20. The actuator system AS2 is another example of an actuator system AS. The drive section 31 is an example of a drive section 3. The flow rate measurement unit 52 is an example of a flow rate measurement unit 5. The tube 42 is an example of a tube 4.

[0069] The driving unit 31 includes a fluid source 311, a pump 312, a first valve 313, a second valve 314, a third valve 323, a fourth valve 324, a first pipe 315, a second pipe 316, a third pipe 325, and a fourth pipe 326. The fluid source 311, the pump 312, the first valve 313, the second valve 314, the first pipe 315, and the second pipe 316 may be configured similarly to the fluid source 301, the pump 302, the first valve 303, the second valve 304, the first pipe 305, and the second pipe 306 of the driving unit 30 of the actuator system AS1.

[0070] The third pipe 325 forms a path for supplying fluid from the fluid source 311 to the flow rate measurement unit 52 (first internal space 5201). The third valve 323 is configured to open and close the path of the third pipe 325. The fourth pipe 326 forms a path for discharging fluid from the flow rate measurement unit 52 to the fluid source 311. The fourth valve 324 is configured to open and close the path of the fourth pipe 326. With regard to other configurations, the drive unit 31 may be configured similarly to the drive unit 30 of the actuator system AS1.

[0071] The flow rate measurement unit 52 is composed of a fluid pressure cylinder 520. Specifically, the flow rate measurement unit 52 includes the fluid pressure cylinder 520, a scale 521, and a measurement sensor 522. The flow rate measurement unit 52 may be configured similarly to the flow rate measurement unit 51, except that the flow rate measurement unit 52 is connected to an internal space of the fluid pressure actuator 20 on the opposite side to the internal space connected to the flow rate measurement unit 51. The fluid pressure cylinder 520, the scale 521, and the measurement sensor 522 may be configured similarly to the fluid pressure cylinder 510, the scale 511, and the measurement sensor 512 of the flow rate measurement unit 51. The measurement sensor 522 is an example of the measurement sensor 5S.

[0072] The fluid pressure cylinder 520 includes a cylinder tube 5200, a piston 5203, and a shaft 5204. The cylinder tube 5200, the piston 5203, and the shaft 5204 may be configured similarly to the cylinder tube 5100, the piston 5103, and the shaft 5104 of the flow rate measuring unit 51. The piston 5203 and the shaft 5204 are an example of the mover 5M of the flow rate measuring unit 5. The first internal space 5201 and the second internal space 5202 of the cylinder tube 5200 may be configured similarly to the first internal space 5101 and the second internal space 5102 of the cylinder tube 5100.

[0073] The tube 42 may connect the fluid pressure actuator 20 and the flow rate measuring unit 52 (fluid pressure cylinder 520) so as to connect the internal spaces of the fluid pressure actuator 20 and the flow rate measuring unit 52 on the same side. In the example of FIG. 4 , the first internal space 201 of the fluid pressure actuator 20 is connected to the flow rate measuring unit 51. Therefore, the tube 42 connects the second internal spaces (202, 5202) of the fluid pressure actuator 20 and the flow rate measuring unit 52 to each other. The second internal spaces (202, 5202) of the fluid pressure actuator 20 and the flow rate measuring unit 52 and the tube 42 may be filled with fluid and then sealed. Similar to the tube 41, the tube 42 may be provided with a pressure gauge 421. The pressure value inside the tube 42 may be measured by the pressure gauge 421. The pressure gauge 421 may be arranged at any location on the tube 42. 4, the pressure gauge 421 may be provided on the inlet side (the end connected to the flow rate measurement unit 52) ​​of the tube 42. Meanwhile, the third pipe 325 and the fourth pipe 326 of the drive unit 31 may be connected to the internal space of the flow rate measurement unit 52 on the side opposite to the side connected to the tube 42. In the example of FIG. 4, the third pipe 325 and the fourth pipe 326 of the drive unit 31 are connected to the first internal space 5201 of the flow rate measurement unit 52.

[0074] As a result, the actuator system AS2 has two paths for transmitting power. The first transmission path is composed of the first pipe 315 and the second pipe 316 of the drive unit 31, the flow rate measuring unit 51, and the tube 41. The second transmission path is composed of the third pipe 325 and the fourth pipe 326 of the drive unit 31, the flow rate measuring unit 52, and the tube 42. The second transmission path can control the supply and discharge of fluid to the second internal space 202 of the fluid pressure actuator 20 in a manner similar to the control of fluid to the first internal space 201 of the fluid pressure actuator 20 by the first transmission path. By controlling the first and second transmission paths, the fluid pressure actuator 20 is configured to be driven in a double-acting manner. In other respects, the actuator system AS2 may be configured similarly to the actuator system AS.

[0075] In this actuator system AS2, by operating the pump 312, opening the first valve 313, and closing the second valve 314, fluid can be supplied from the fluid source 311 to the second internal space 5102 of the flow rate measuring unit 51. In addition, by closing the third valve 323 and opening the fourth valve 324, fluid can be discharged from the first internal space 5201 of the flow rate measuring unit 52 to the fluid source 311. The supply of fluid to the second internal space 5102 of the flow rate measuring unit 51 causes the piston 5103 to retract (move to the right in the figure). When the piston 5103 retracts, fluid flows from the first internal space 5101 of the flow rate measuring unit 51 into the tube 41. In response to this, fluid is supplied from the tube 41 to the first internal space 201 of the fluid pressure actuator 20. Furthermore, the discharge of fluid from the first internal space 5201 of the flow rate measuring unit 52 causes the piston 5203 to retract (move to the left in the figure). When the piston 5203 retracts, the fluid flows out from the tube 42 into the second internal space 5202 of the flow rate measuring unit 52. In response to this, the fluid is discharged from the second internal space 202 of the fluid pressure actuator 20 into the tube 42. When the fluid is supplied to the first internal space 201 of the fluid pressure actuator 20 and the fluid is discharged from the second internal space 202, the piston 203 and the shaft 204 of the fluid pressure actuator 20 are driven forward (to the right in the figure).

[0076] On the other hand, by closing the first valve 313 and opening the second valve 314, fluid can be discharged from the second internal space 5102 of the flow rate measuring unit 51 to the fluid source 311. In addition, by opening the third valve 323 and closing the fourth valve 324, fluid can be supplied from the fluid source 311 to the first internal space 5201 of the flow rate measuring unit 52. The piston 5103 advances (moves leftward in the figure) due to the fluid being discharged from the second internal space 5102 of the flow rate measuring unit 51. When the piston 5103 advances, fluid flows out from the tube 41 into the first internal space 5101 of the flow rate measuring unit 51. In response to this, fluid is discharged from the first internal space 201 of the fluid pressure actuator 20 to the tube 41. Furthermore, the piston 5203 advances (moves rightward in the figure) due to the fluid being supplied to the first internal space 5201 of the flow rate measuring unit 52. When the piston 5203 moves forward, fluid flows from the second internal space 5202 of the flow rate measuring unit 52 into the tube 42. In response, fluid is supplied from the tube 42 to the second internal space 202 of the fluid pressure actuator 20. When fluid is discharged from the first internal space 201 of the fluid pressure actuator 20 and fluid is supplied to the second internal space 202, the piston 203 and shaft 204 of the fluid pressure actuator 20 are driven in the backward direction (toward the left in the figure). The series of drive operations in the forward and backward directions described above is an example of an operation in which the mover 5M of the flow rate measuring unit 5 is driven in response to the drive of the mover 2M of the fluid pressure actuator 2. Note that the piston 203 and shaft 204 of the fluid pressure actuator 20 can be stopped by opening all the valves (313, 314, 323, 324). Furthermore, the piston 203 and shaft 204 of the fluid pressure actuator 20 can be fixed by closing all the valves (313, 314, 323, 324).

[0077] The control device 1 may be directly or indirectly connected to each of the valves (313, 314, 323, 324). By controlling the opening and closing of the valves (313, 314, 323, 324), it is possible to control the driving of the fluid pressure actuator 20 via each of the flow rate measurement units (51, 52).

[0078] Furthermore, the first transmission path and the second transmission path transmit approximately the same amount of power in opposite directions. That is, the second internal space 202 of the fluid pressure actuator 20 decreases by the amount that the first internal space 201 increases. The first internal space 201 decreases by the amount that the second internal space 202 increases. Therefore, compensation for tube deformation only needs to be performed on at least one of the two tubes (41, 42). Therefore, the control device 1 may be directly or indirectly connected to at least one of the pressure gauge 411 of the tube 41 and the pressure gauge 421 of the tube 42. The control device 1 may acquire the pressure value in at least one of the two tubes (41, 42) as the pressure value 125 from at least one of the two pressure gauges (411, 421). Either one of the two pressure gauges (411, 421) may be omitted.

[0079] Similarly, the control device 1 may be directly or indirectly connected to at least one of the two measurement sensors (512, 522). The control device 1 may acquire, from at least one of the two measurement sensors (512, 522), a measurement value 127 of at least one of the amount of fluid inflow from the flow rate measuring unit 51 to the tube 41 and the amount of fluid inflow from the flow rate measuring unit 52 to the tube 42. Either one of the two measurement sensors (512, 522) may be omitted. If the measurement sensor 512 is omitted, the scale 511 may also be omitted. If the measurement sensor 522 is omitted, the scale 521 may also be omitted.

[0080] (Flow rate measurement unit omitted) Fig. 5 schematically shows an example of the configuration of an actuator system AS3 according to this embodiment. In the example of Fig. 5, the actuator system AS3 includes a drive unit 30, a flow meter 50, a tube 41, and a fluid pressure actuator 20. The actuator system AS3 is another example of the actuator system AS. The actuator system AS3 of Fig. 5 can be configured by omitting the flow rate measurement unit 51 from the actuator system AS1 and adding the flow meter 50. Except for the omission of the flow rate measurement unit 51 and the inclusion of the flow meter 50, the actuator system AS3 may be configured similarly to the actuator system AS1.

[0081] In this actuator system AS3, the tube 41 may be directly connected to each pipe (305, 306) of the drive unit 30. The flow meter 50 may be disposed at or near the connection between the drive unit 30 and the tube 41. The control device 1 may be directly or indirectly connected to the flow meter 50, and may obtain a measured value 127 of the amount of fluid inflow from the drive unit 30 to the tube 41 from the flow meter 50. The drive of the fluid pressure actuator 20 in this actuator system AS3 can be controlled in the same manner as in the actuator system AS1, except that the flow measurement unit 51 is used as a relay.

[0082] Note that the configuration in which the flow rate measurement unit (flow rate measurement unit 51) can be omitted does not have to be limited to the configuration of the actuator system AS1. In another example, at least one of the two measurement units (51, 52) may be omitted in the actuator system AS2. When the flow rate measurement unit 51 is omitted, the tube 41 may be connected to the first pipe 315 and the second pipe 316 of the drive unit 31, as in the actuator system AS3, and a flow meter may be provided at or near the connection. Similarly, when the flow rate measurement unit 52 is omitted, the tube 42 may be connected to the third pipe 325 and the fourth pipe 326 of the drive unit 31, and a flow meter may be provided at or near the connection.

[0083] (Master Actuator) Fig. 6 schematically shows an example of the configuration of an actuator system AS4 according to this embodiment. In the example of Fig. 6, the actuator system AS4 includes a drive section 30, a flow rate measurement unit 51, a tube 41, a fluid pressure actuator 20, and a master actuator 61. The actuator system AS4 is another example of the actuator system AS. The actuator system AS4 in Fig. 6 can be configured by adding the master actuator 61 to the actuator system AS1. Except for the fact that the actuator system AS4 further includes the master actuator 61, the actuator system AS4 may be configured similarly to the actuator system AS1.

[0084] The master actuator 61 may be configured similarly to the fluid pressure actuator 20. The master actuator 61 includes a cylinder tube 610, a piston 613, and a shaft 614. The cylinder tube 610, the piston 613, and the shaft 614 may be configured similarly to the cylinder tube 200, the piston 203, and the shaft 204 of the fluid pressure actuator 20. The first internal space 611 and the second internal space 612 of the cylinder tube 610 may be configured similarly to the first internal space 201 and the second internal space 202 of the cylinder tube 200.

[0085] The master actuator 61 may be connected to the flow rate measurement unit 51 in a similar manner to the fluid pressure actuator 20. In the example of Fig. 6, a first internal space 611 of the master actuator 61 may be connected to a first internal space 5101 of the flow rate measurement unit 51 (fluid pressure cylinder 510) via a tube 615. The first internal spaces (5101, 611) of the flow rate measurement unit 51 and the master actuator 61, and the tube 615 may be filled with fluid and then sealed. As a result, in this actuator system AS4, it is possible to control the driving of the fluid pressure actuator 20 via the master actuator 61.

[0086] Specifically, by closing the first valve 303 and opening the second valve 304, the position of the piston 5103 of the flow rate measurement unit 51 is not fixed, and a state can be created in which the master actuator 61 and the fluid pressure actuator 20 are not linked. In this state, the master actuator 61 and the flow rate measurement unit 51 can be driven freely, regardless of the drive of the fluid pressure actuator 20. For example, by advancing the piston 613 and shaft 614 of the master actuator 61 (moving them to the left in the figure), fluid can be drawn from the first internal space 5101 of the flow rate measurement unit 51 to the first internal space 611 of the master actuator 61 via the tube 615. This outflow of fluid from the flow rate measurement unit 51 to the master actuator 61 allows the piston 5103 of the flow rate measurement unit 51 to be moved backward (moving them to the right in the figure) in accordance with the drive of the master actuator 61. Similarly, by retracting the piston 613 and shaft 614 of the master actuator 61 (moving them to the right in the figure), it is possible to supply fluid from the first internal space 611 of the master actuator 61 to the first internal space 5101 of the flow rate measuring unit 51 via the tube 615. As a result, the piston 5103 of the flow rate measuring unit 51 can be moved forward (moved to the left in the figure) in accordance with the driving of the master actuator 61.

[0087] On the other hand, by controlling the position of the piston 5103 of the flow rate measuring unit 51 by opening and closing each valve (303, 304), the position of the piston 5103 can be fixed at a reference position. The reference position may be set arbitrarily. Fixing the piston 5103 at the reference position creates a state in which the master actuator 61 and the fluid pressure actuator 20 are interlocked. That is, as the piston 613 of the master actuator 61 advances, fluid can be drawn from the fluid pressure actuator 20 to the master actuator 61 via the tubes (615, 41) and the flow rate measuring unit 51. This allows the piston 203 of the fluid pressure actuator 20 to retract in conjunction with the advancement of the piston 613 of the master actuator 61. Furthermore, as the piston 613 of the master actuator 61 retracts, fluid can be supplied from the master actuator 61 to the fluid pressure actuator 20 via the tubes (615, 41) and the flow rate measuring unit 51. This allows the piston 203 of the fluid pressure actuator 20 to advance in conjunction with the retraction of the piston 613 of the master actuator 61. However, the pressure inside the tube 41 measured by the pressure gauge 411 may increase or decrease due to a load acting on the shaft 204 of the fluid pressure actuator 20. This change in pressure causes the tube 41 to deform (expand or contract). This deformation of the tube 41 may cause an error between the drive amounts of the master actuator 61 and the fluid pressure actuator 20. Therefore, even in this interlocked state, the control device 1 may compensate for the deformation of the tube 41 according to the pressure value 125. As an example, the control device 1 may calculate the error due to the deformation of the tube 41 according to the pressure value 125. Then, the control device 1 may change the position control of the piston 5103 in the flow rate measuring unit 51 so as to move the piston 5103 forward or backward by the calculated error. This makes it possible to correct the error between the drive amounts of the master actuator 61 and the fluid pressure actuator 20, thereby synchronizing the positions of the piston 613 of the master actuator 61 and the piston 203 of the fluid pressure actuator 20.

[0088] The material of the tube 615 is not particularly limited and may be selected appropriately depending on the embodiment. In one example, a rigid tube may be used for the tube 615. In another example, to improve maneuverability, a flexible tube may be used for the tube 615, similar to the tube 41. In this case, a pressure gauge configured to measure the pressure inside the tube 615 may be provided on the tube 615. When accepting the drive of the master actuator 61, the control device 1 may acquire the value of the pressure inside the tube 615 from the pressure gauge in the same manner as the tube 41, and compensate for the deformation of the tube 615 according to the acquired pressure value.

[0089] FIG. 7 schematically illustrates an example of the configuration of an actuator system AS5 according to this embodiment. In the example illustrated in FIG. 7 , the actuator system AS5 includes a drive unit 31, a (first) flow rate measurement unit 51, a (second) flow rate measurement unit 52, a (first) tube 41, a (second) tube 42, a fluid pressure actuator 20, and a master actuator 62. The actuator system AS5 is another example of the actuator system AS. The actuator system AS5 in FIG. 7 can be configured by adding a master actuator 62 to an actuator system AS2 that includes a fluid pressure actuator 20 configured for double-acting drive. Except for the inclusion of the master actuator 62, the actuator system AS5 may be configured similarly to the actuator system AS2.

[0090] The master actuator 62 may be configured similarly to the fluid pressure actuator 20. The master actuator 62 includes a cylinder tube 620, a piston 623, and a shaft 624. The cylinder tube 620, the piston 623, and the shaft 624 may be configured similarly to the cylinder tube 200, the piston 203, and the shaft 204 of the fluid pressure actuator 20. The first internal space 621 and the second internal space 622 of the cylinder tube 620 may be configured similarly to the first internal space 201 and the second internal space 202 of the cylinder tube 200.

[0091] The master actuator 62 may be connected to each of the flow rate measurement units (51, 52) in a manner similar to that of the fluid pressure actuator 20. In the example of FIG. 7 , a first internal space 621 of the master actuator 62 may be connected to a first internal space 5101 of the flow rate measurement unit 51 via a tube 625. A second internal space 622 of the master actuator 62 may be connected to a second internal space 5202 of the flow rate measurement unit 52 via a tube 626. The first internal spaces (5101, 621) of the flow rate measurement unit 51 and the master actuator 62 and the tube 625 may be filled with a fluid and then sealed. Similarly, the second internal spaces (5202, 622) of the flow rate measurement unit 52 and the master actuator 62 and the tube 626 may be filled with a fluid and then sealed. As a result, in this actuator system AS5, the driving of the fluid pressure actuator 20 can be controlled via the master actuator 62.

[0092] Specifically, by closing the first valve 313 and the third valve 323 and opening the second valve 314 and the fourth valve 324, the positions of the pistons (5103, 5203) of the flow rate measurement units (51, 52) can be freely set. This makes it possible to create a state in which the master actuator 62 and the fluid pressure actuator 20 are not linked. In this state, the master actuator 62 and the flow rate measurement units (51, 52) can be driven freely, regardless of the driving of the fluid pressure actuator 20.

[0093] On the other hand, by opening and closing each valve (313, 314, 323, 324), the position of each piston (5103, 5203) can be controlled, thereby fixing the position of each piston (5103, 5203) at a reference position. This allows the master actuator 62 and the fluid-pressure actuator 20 to be interlocked, similar to the actuator system AS4. That is, as the piston 623 of the master actuator 62 advances, fluid can be drawn from the first internal space 201 of the fluid-pressure actuator 20 to the first internal space 621 of the master actuator 62 via the tubes (625, 41) and the flow rate measuring unit 51. Furthermore, fluid can be supplied from the second internal space 622 of the master actuator 62 to the second internal space 202 of the fluid-pressure actuator 20 via the tubes (626, 41) and the flow rate measuring unit 52. This allows the piston 203 of the fluid-pressure actuator 20 to retreat in conjunction with the advancement of the piston 623 of the master actuator 62. Furthermore, in accordance with the retraction of the piston 623 of the master actuator 62, fluid can be supplied from the first internal space 621 of the master actuator 62 to the first internal space 201 of the fluid pressure actuator 20 via the tubes (625, 41) and the flow rate measuring unit 51. Furthermore, fluid can be drawn from the second internal space 202 of the fluid pressure actuator 20 to the second internal space 622 of the master actuator 62 via the tubes (626, 41) and the flow rate measuring unit 52. As a result, the piston 203 of the fluid pressure actuator 20 can be advanced in conjunction with the retraction of the piston 623 of the master actuator 62.

[0094] In this case, as in the actuator system AS4, the pressure in each tube (41, 42) may increase or decrease due to a load acting on the shaft 204 of the fluid pressure actuator 20. Therefore, in this actuator system AS5, the control device 1 may also change the position control of the two flow rate measurement units (51, 52) to compensate for deformation of at least one of the two tubes (41, 42). In one example, the control device 1 may calculate an error due to deformation of the tube 41 according to the pressure value measured by the pressure gauge 411. The control device 1 may then change the position control of the piston 5103 in the flow rate measurement unit 51 so as to move the piston 5103 forward or backward by the calculated error. The control device 1 may also calculate an error due to deformation of the tube 42 according to the pressure value measured by the pressure gauge 421. The control device 1 may then change the position control of the piston 5203 in the flow rate measurement unit 52 so as to move the piston 5203 forward or backward by the calculated error. This makes it possible to correct the error between the drive amounts of the master actuator 62 and the fluid pressure actuator 20, and as a result, the positions of the piston 623 of the master actuator 62 and the piston 203 of the fluid pressure actuator 20 can be synchronized.

[0095] Note that correction of position control due to tube deformation may be performed by at least one of the two flow rate measurement units (51, 52). Furthermore, fixing of the piston by position control may be performed by at least one of the two flow rate measurement units (51, 52). By fixing the piston by position control using only one of the two flow rate measurement units (51, 52), it is possible to create a state in which one is free and the other is interlocked. As an example, assume that position control and compensation for deformation of the tube 41 are performed only by the flow rate measurement unit 51, and the piston 5203 of the flow rate measurement unit 52 is not fixed. In this state, when the piston 623 of the master actuator 62 is moved in the backward direction, fluid is supplied from the master actuator 62 to the fluid pressure actuator 20, and the path of the tube 41 becomes positive pressure. On the other hand, when the piston 623 of the master actuator 62 is moved in the forward direction, fluid is drawn from the fluid pressure actuator 20 to the master actuator 62 while the path of the tube 42 is free, resulting in a negative pressure in the path of the tube 41. When the fluid is water, the pressure that can be transmitted under negative pressure is, for example, about 0.1 MPa, and the pressure that can be transmitted under positive pressure is, for example, about 5.0 MPa. Therefore, a difference occurs in the magnitude of the transmitted pressure when the shaft 204 of the fluid pressure actuator 20 is driven in the backward direction by moving the piston 623 of the master actuator 62 in the forward direction, and when the shaft 204 is driven in the forward direction by moving the piston 623 in the backward direction. When the piston 5103 of the flow rate measurement unit 51 is fixed and the piston 5203 of the flow rate measurement unit 52 is not fixed, the shaft 204 of the fluid pressure actuator 20 can be driven with a large driving force in the forward direction but with a small driving force in the backward direction. Conversely, when the piston 5103 of the flow rate measuring unit 51 is not fixed and the piston 5203 of the flow rate measuring unit 52 is fixed, the shaft 204 of the fluid pressure actuator 20 can be driven with a large driving force in the backward direction, but with a small driving force in the forward direction.Therefore, the control device 1 may not fix the piston 5103 of the flow rate measuring unit 51 and may fix the piston 5203 of the flow rate measuring unit 52 until the shaft 204 comes into contact with an object and a load acts on the shaft 204, thereby preventing a large driving force from being transmitted to the shaft 204. After contact with the object, the control device 1 may switch the status of the position control so that the piston 5103 of the flow rate measuring unit 51 is fixed and the piston 5203 of the flow rate measuring unit 52 is not fixed, depending on the purpose, for example, to move the object, thereby allowing a large driving force to be transmitted to the shaft 204.

[0096] The material of each tube (625, 626) is not particularly limited and may be selected appropriately depending on the embodiment. In one example, each tube (625, 626) may be a rigid tube. In another example, to improve maneuverability, at least one of the two tubes (625, 626) may be a flexible tube, similar to the tube 41. In this case, when accepting the drive of the master actuator 62, the control device 1 may acquire a pressure value in at least one of the two tubes (625, 626) in the same manner as the tube 41, and compensate for deformation of the tube 615 according to the acquired pressure value. A pressure gauge may be used to measure the pressure value.

[0097] [Control Scheme] The control scheme of the fluid pressure actuator 2 is not particularly limited and may be determined appropriately depending on the embodiment, as long as it includes a term that compensates for deformation of the tube 4 in accordance with the pressure value 125 inside the tube 4. A known method such as PID control may be adopted to control the fluid pressure actuator 2.

[0098] 8 is a schematic diagram illustrating an example of a control scheme according to this embodiment. In the example illustrated in FIG. 8, the actuator system AS1 in FIG. 3 is used as the actuator system AS, and PID control is used to control the position of the piston 203 in the fluid pressure actuator 20. ｔＡｃｔ indicates the target position of the piston 203. The target position may be determined appropriately. Ｏｐindicates the value of the current position of the piston 5103 measured by the measurement sensor 512 of the flow rate measurement unit 51. The value x measured by the measurement sensor 512 Ｏｐ is an example of the measurement value 127, and is an example of the (current) position of the mover 5M of the flow rate measuring unit 5. The estimated value x ｅＡｃｔ is calculated by the following equation 1: Ｏｐ can be inferred from

[0099] S Ｏｐ indicates the cross-sectional area of ​​the internal space (5101, 5102) of the cylinder tube 5100 in the flow rate measuring unit 51. Ａｃｔ indicates the cross-sectional area of ​​the internal space (201, 202) of the cylinder tube 200 in the fluid pressure actuator 20. Equation 1 is an example of the correspondence relationship between the drive amount of the mover 2M of the fluid pressure actuator 2 and the mover 5M of the flow rate measuring unit 5. H indicates a function that compensates for the tube 41. Since Equation 1 includes H, the estimated value x of the current position of the piston 203 of the fluid pressure actuator 20 ｅＡｃｔ In this case, the deformation of the tube 41 according to the pressure value 125 can be compensated for. That is, the inclusion of the term H in this equation 1 is an example of compensating for the deformation of the tube 4 according to the pressure value 125. The estimated value x of the current position of the piston 203 calculated by equation 1 ｅＡｃｔ is an example of the position of the mover 2M of the fluid pressure actuator 2 that is estimated while compensating for the deformation of the tube 4 in accordance with the position of the mover 5M of the flow rate measurement unit 5. The compensation function H of the tube 41 can be expressed by the following equation 2.

[0100] p indicates the pressure value 125 inside the tube 41. The value of p can be obtained from the pressure gauge 411. R indicates the inner radius (initial value) of the tube 41. t indicates the thickness of the tube 41. L indicates the length (initial value) of the tube 41. E indicates the Young's modulus of the material used for the tube 41. ν indicates the Poisson's ratio. As shown in Equation 2, the compensation amount (compensation function H) for the position of the piston 203 is calculated based on the volume change amount ΔV of the tube 41. ｔ(p, R, t, L, E, ν) and the initial value of the volume change amount ΔV ｔ０ The difference between these two is the cross-sectional area S of the cylinder tube 200 in the fluid pressure actuator 20. Ａｃｔ It can be obtained by dividing by.

[0101] The parameter values ​​included in the compensation function H of the tube 41 may be obtained as appropriate depending on the embodiment. The parameter values ​​of the compensation function H may be at least partially derived theoretically. As an example, assuming that the pressure p inside the tube 41 is 0 as the initial state, the increase ΔR in the inner radius of the tube 41 can be derived using the following Equation 3.

[0102] K Ｒ is a constant, the cross-sectional area A of the tube 41 ｔ can be derived by the following equation 4.

[0103] On the other hand, the increase ΔL in the length direction of the tube 41 can be derived by the following equation 5.

[0104] K Ｌ is approximately a constant, the current value L of the length of the tube 41 ｅ can be derived by the following equation 6.

[0105] Therefore, the volume V in the tube 41 ｔ can be derived by the following equation 7.

[0106] In addition, the initial value of the volume inside the tube 41 is V ｔ０ Then, the volume change amount ΔV of the tube 41 is ｔ can be derived by the following equation 8.

[0107] By expanding Equation 8, the following Equation 9 can be obtained.

[0108] From this equation 9, the volume change amount ΔV that constitutes the compensation function H of the tube 41 is ｔIt is considered that the pressure p of the tube 41 can be modeled by a third-order polynomial. ｔ may be expressed as a third- or higher-order polynomial of the pressure p. In one example, the compensation function H may be obtained by using attribute values ​​of the tube 41 (inner radius R, length L, thickness t, Young's modulus E, and Poisson's ratio ν) for the values ​​of each parameter in Equation 9. In another example, the values ​​of the parameters included in the compensation function H of the tube 41 may be obtained from actual values ​​by known methods such as fitting and machine learning. The compensation function H may be configured by a neural network or the like.

[0109] The control device 1 determines the target position x of the piston 203. ｔＡｃｔ and the estimated value of the current position x ｅＡｃｔ The deviation e of the piston 5103 may be calculated, and the position of the piston 203 may be PID controlled according to the calculated deviation e. Ｏｐ and the deviation e is the value x Ｏｐ Therefore, controlling the position of the piston 203 in accordance with this deviation e is an example of driving the fluid pressure actuator 2 in accordance with the measurement value 127 acquired from the measurement sensor 5S.

[0110] K in FIG. ｐ represents the gain of the proportional control. ｉ denotes the gain of the integral control. ｄ indicates the gain of the differential control. The control device 1 may obtain the control input value θ for the control object from the deviation e by performing a PID control calculation. The control object may be, for example, each valve (303, 304), and the control input value θ may be, for example, the opening degree of each valve (303, 304). The control device 1 may drive the fluid pressure actuator 20 by controlling the control object in accordance with the obtained control input value θ. In this way, the control device 1 may control the control amount (position of the piston 203) of the fluid pressure actuator 20. The control device 1 may obtain the current position value x of the piston 5103 measured by the measurement sensor 512 of the flow rate measurement unit 51. ＯｐBy repeating the process from the acquisition of the parameter, it is possible to continuously control the position of the piston 203 of the fluid pressure actuator 20. Furthermore, according to the control scheme of FIG. 8, it is possible to simultaneously control the operation of the fluid pressure actuator 20 while estimating the position of the mover (piston 203 and shaft 204) of the fluid pressure actuator 20. Furthermore, by compensating for deformation of the tube 41 when estimating the position of the mover, it is expected that the estimation accuracy of the position of the mover will be improved. As a result, it is also expected that the controllability of the fluid pressure actuator 20 will be improved.

[0111] The control method for the fluid pressure actuator 2 (fluid pressure actuator 20) is not limited to this example, and may be modified as appropriate depending on the embodiment. In the example of FIG. 8 , the position of the piston 203 is the control target, but a control amount other than the position of the piston 203 may also be the control target. In another example, the driving force output from the piston 203 may also be the control target. Furthermore, even in configurations other than the actuator system AS1, the control device 1 may control the drive of the fluid pressure actuator 2 (fluid pressure actuator 20) while compensating for deformation of the tube 4 (tube 41, tube 42). For example, in the actuator system AS2, a control method similar to that of the actuator system AS1 can be adopted. In the actuator system AS3, the flow rate of fluid flowing into the tube 41 is measured by the flow meter 50. In the above formula 1, x Ｏｐ If the reference position of is 0, then "x Ｏｐ ×S Ｏｐ " corresponds to the amount of fluid flowing from the flow rate measuring unit 51 into the tube 41. Therefore, when the actuator system AS3 is used, "x Ｏｐ ×S Ｏｐ By substituting the measurement value of the flow meter 50 into ", the estimated value x of the current position of the piston 203 of the fluid pressure actuator 20 is obtained. ｅＡｃｔ can be calculated.

[0112] §2 Configuration Example [Hardware Configuration] Fig. 9 shows a schematic diagram of an example of the hardware configuration of the control device 1 according to this embodiment. In the example shown in Fig. 9, the control device 1 according to this embodiment is a computer to which a control unit 11, a storage unit 12, an external interface 13, an input device 14, an output device 15, and a drive 16 are electrically connected.

[0113] The control unit 11 includes a hardware processor such as a central processing unit (CPU), a random access memory (RAM), and a read-only memory (ROM), and is configured to execute information processing based on programs and various data. The control unit 11 (CPU) is an example of a processor resource.

[0114] The storage unit 12 may be configured, for example, with a hard disk drive, a solid state drive, or the like. The storage unit 12 (and RAM, ROM) are examples of memory resources. In this embodiment, the storage unit 12 stores various information such as a control program 81. The control program 81 is a program for causing the control device 1 to execute information processing (see FIG. 11 described below) related to the operational control of the fluid pressure actuator 2. The control program 81 includes a series of commands for this information processing.

[0115] The external interface 13 is an interface for connecting to an external device. The external interface 13 may include, for example, a Universal Serial Bus (USB) port, a dedicated port, etc. The external interface 13 may include, for example, a communication interface such as a wired Local Area Network (LAN) module, a wireless LAN module, etc. The type and number of external interfaces 13 may be selected arbitrarily. In this embodiment, the control device 1 may be connected to each component of the actuator system AS (for example, a valve, a measurement sensor, a pressure gauge, etc.) via the external interface 13.

[0116] The input device 14 is a device for receiving information input from an operator. The input device 14 may include, for example, a mouse, a keyboard, an operator, etc. The output device 15 is a device for outputting information to the operator. The output device 15 may include, for example, a display, a speaker, etc. The operator can operate the control device 1 by using the input device 14 and the output device 15. The input device 14 and the output device 15 may be integrated into one device, such as a touch panel display. The input device 14 and the output device 15 may be connected via the external interface 13.

[0117] The drive 16 is a device for reading various information, such as programs, stored in a storage medium 91. The storage medium 91 may be configured to store various information, such as stored programs, by electrical, magnetic, optical, mechanical, or chemical action so that a machine, such as a computer, can read the information. The control program 81 may be stored in the storage medium 91 instead of or together with the storage unit 12. The control device 1 may acquire the control program 81 from the storage medium 91. The storage medium 91 may be a disk-type storage medium, such as a CD or DVD, or a non-disk-type storage medium, such as a semiconductor memory (e.g., a flash memory). The type of the drive 16 may be selected appropriately depending on the type of the storage medium 91. The drive 16 may be connected via an external interface 13.

[0118] Note that, with regard to the specific hardware configuration of the control device 1, components may be omitted, replaced, or added as appropriate depending on the embodiment. For example, the control unit 11 may include multiple hardware processors. The type of hardware processor is not particularly limited and may be selected as appropriate depending on the embodiment. The storage unit 12 may be configured with RAM and ROM included in the control unit 11. At least one of the external interface 13, the input device 14, the output device 15, and the drive 16 may be omitted. The control device 1 may be configured with multiple computers. In this case, the hardware configurations of the computers may or may not be the same. Furthermore, the control device 1 may be an information processing device designed specifically for the service provided, as well as a general-purpose personal computer (PC), a tablet PC, a mobile terminal (including a smartphone), a general-purpose server device (which may include a virtual computer, a cloud-based computer, etc.), etc.

[0119] [Software Configuration] Fig. 10 schematically shows an example of the software configuration of the control device 1 according to this embodiment. The control unit 11 of the control device 1 executes instructions included in the control program 81 stored in the storage unit 12 using the CPU. As a result, the control device 1 according to this embodiment operates as a computer including an information acquisition unit 111 and an operation control unit 112 as software modules. That is, in this embodiment, each software module of the control device 1 is realized by the control unit 11 (CPU).

[0120] The information acquiring unit 111 is configured to acquire a pressure value 125 in the tube 4. If the actuator system AS includes a flow rate measurement unit 5, the information acquiring unit 111 may be further configured to acquire a measurement value 127 of the amount of fluid inflow into the tube 4 from the flow rate measurement unit 5 from the measurement sensor 5S. The operation control unit 112 is configured to drive the fluid pressure actuator 2 while compensating for deformation of the tube 4 in accordance with the acquired pressure value 125. When the measurement value 127 of the amount of fluid inflow into the tube 4 has been obtained, the operation control unit 112 may be configured to drive the fluid pressure actuator 2 in accordance with the acquired measurement value 127.

[0121] In this embodiment, an example is described in which each software module of the control device 1 is implemented by a general-purpose CPU. However, some or all of the software modules may be implemented by one or more dedicated processors or chipsets. Each module may be implemented as a hardware module. Furthermore, with regard to the software configuration of the control device 1, software modules may be omitted, replaced, or added as appropriate depending on the embodiment.

[0122] §3 Operation Example Figure 11 is a flowchart showing an example of the processing procedure of the control device 1 according to this embodiment. The processing procedure of the control device 1 described below is an example of a control method (information processing method) executed by a computer. However, the processing procedure described below is merely an example, and each step may be modified as much as possible. Furthermore, steps may be omitted, replaced, or added to the following processing procedure as appropriate depending on the embodiment.

[0123] (Step S101 ) In step S101 , the control unit 11 operates as the information acquisition unit 111 and acquires the pressure value 125 inside the tube 4 .

[0124] As an example, when the actuator systems (AS1, AS3, AS4) are employed, the control unit 11 may acquire the pressure value 125 inside the tube 41 from the pressure gauge 411. When the actuator systems (AS2, AS5) are employed, the control unit 11 may acquire the pressure value 125 inside at least one of the two tubes (41, 42) from at least one of the two pressure gauges (411, 421).

[0125] In one example, when the actuator system AS includes a flow rate measurement unit 5, the control unit 11 may further acquire a measurement value 127 of the amount of fluid flowing into the tube 4 from the flow rate measurement unit 5 from the measurement sensor 5S. When the actuator systems (AS1, AS4) are employed, the control unit 11 may acquire the measurement value 127 from the measurement sensor 512 of the flow rate measurement unit 51. When the actuator systems (AS2, AS5) are employed, the control unit 11 may acquire the measurement value 127 from at least one of the two measurement sensors (512, 522). In another example, when the actuator system AS3 is employed, the control unit 11 may acquire the measurement value 127 of the amount of fluid flowing into the tube 41 from the flow meter 50. The order in which the pressure value 125 and the measurement value 127 are acquired is not particularly limited and may be selected appropriately depending on the embodiment. The process of acquiring the pressure value 125 and the process of acquiring the measurement value 127 may be performed at least partially in parallel. When the pressure value 125 is acquired, the control unit 11 advances the process to the next step S102.

[0126] (Step S102) In step S102, the control unit 11 operates as the operation control unit 112, and drives the fluid pressure actuator 2 while compensating for the deformation of the tube 4 according to the acquired pressure value 125.

[0127] In one example, when the actuator systems (AS1, AS3, AS4) are employed, the control unit 11 may drive the fluid pressure actuator 20 while compensating for deformation of the tube 41. When the actuator systems (AS2, AS5) are employed, the control unit 11 may drive the fluid pressure actuator 20 while compensating for deformation of at least one of the two tubes (41, 42).

[0128] In one example, when a measurement value 127 of the amount of fluid inflow into the tube 4 is obtained, the control unit 11 may drive the fluid pressure actuator 2 in accordance with the obtained measurement value 127. As a specific example, the control unit 11 may control the driving of the fluid pressure actuator 2 (fluid pressure actuator 20) in accordance with the control scheme of Fig. 8. After controlling the driving of the fluid pressure actuator 2, the control unit 11 proceeds to the next step S103.

[0129] (Step S103) In step S103, the control unit 11 determines whether or not to end the control of the drive of the fluid pressure actuator 2.

[0130] The criteria for the determination may be set arbitrarily. In one example, the control unit 11 may determine that the control process of the fluid pressure actuator 2 should not be terminated until an arbitrary termination instruction is given. If it is determined that the control process of the fluid pressure actuator 2 should not be terminated, the control unit 11 returns the process to step S101 and executes the process again from step S101. On the other hand, if an arbitrary termination instruction is given, the control unit 11 may determine that the control process of the fluid pressure actuator 2 should be terminated. If it is determined that the control process of the fluid pressure actuator 2 should be terminated, the control unit 11 terminates the processing procedure related to this operation example.

[0131] For example, in response to an operator's operation of the input device 14, the control unit 11 may repeatedly execute the processes of steps S101 and S102 described above from the time when it receives a request to start operation of the fluid pressure actuator 2 until it receives a request to end operation. In this way, the control unit 11 may continuously control the operation of the fluid pressure actuator 2 from the time when it receives a request to start operation to the time when it receives a request to end operation.

[0132] [Features] As described above, in this embodiment, by using a flexible tube 4, it is possible to improve the maneuverability of the operating parts including the fluid pressure actuator 2. Furthermore, in the processing of step S102, the control device 1 controls the drive of the fluid pressure actuator 2 while compensating for deformation of the tube 4 according to the pressure value 125 inside the tube 4. This makes it possible to suppress a decrease in the control accuracy of the fluid pressure actuator 2 caused by the flexibility of the tube 4. Therefore, according to this embodiment, it is possible to improve the maneuverability and to expect appropriate control of the fluid pressure actuator 2.

[0133] §4 Modifications Although the embodiments of the present disclosure have been described in detail above, the above description is merely an example of the present disclosure in every respect. The processes and means described in the present disclosure can be freely combined and implemented as long as no technical contradiction occurs. Various improvements or modifications may be made to the above embodiments as appropriate.

[0134] <4.1> In the above embodiment, the pressure acting inside the tube 4 may change depending on the load acting on the mover 2M of the fluid pressure actuator 2, such as the shaft 204 of the fluid pressure actuator 20. Therefore, the control device 1 may control the driving of the fluid pressure actuator 2 to change the position of the mover 2M of the fluid pressure actuator 2, and acquire the pressure value 125 inside the tube 4 measured when the mover 2M is controlled to each position. The manner in which the position of the mover 2M is changed may be selected appropriately depending on the embodiment. For example, when a fluid pressure actuator 20 (fluid pressure cylinder) is used, the control device 1 may swing the shaft 204 of the fluid pressure actuator 20 back and forth from a reference position, gradually advance the shaft 204, gradually retreat the shaft 204, or randomly change the position from a reference position (position reference value). The control device 1 may then estimate the characteristics of the load acting on the mover 2M of the fluid pressure actuator 2 based on the tendency of the pressure value 125 obtained for each position. The load characteristics may include, for example, whether or not the mover 2M is in contact with an object, the weight of the object in contact, the hardness of the object in contact, etc.

[0135] 12A and 12B schematically show an example of a situation in which a load acts on the shaft 204 of the fluid pressure actuator 20 (the mover 2M of the fluid pressure actuator 2). Fig. 13A is a diagram for explaining the characteristics of the load acting in the situation of Fig. 12A. Fig. 13B is a diagram for explaining the characteristics of the load acting in the situation of Fig. 12B.

[0136] In the example shown in FIG. 12A , the shaft 204 of the fluid pressure actuator 20 faces vertically upward, and an object OM is placed on the shaft 204 of the fluid pressure actuator 20. In this case, a constant load acts on the shaft 204. That is, the scene shown in FIG. 12A is an example of a scene in which a constant load acts on the mover 2M of the fluid pressure actuator 2. When a constant load acts on the shaft 204, as shown in FIG. 13A , the pressure value 125 obtained at each position tends to be constant. Therefore, the control device 1 may estimate that a constant load is acting on the shaft 204 of the fluid pressure actuator 20 (the mover 2M of the fluid pressure actuator 2) when the pressure value 125 obtained at each position is constant or can be approximated as constant. Furthermore, the control device 1 may estimate the magnitude of the load acting from the pressure value 125.

[0137] On the other hand, in the example of FIG. 12B , an elastic (spring-like) load is acting on the shaft 204 from the object OM. The scene of FIG. 12B is an example of a scene in which an elastic load is acting on the mover 2M of the fluid pressure actuator 2. This elastic load may occur depending on, for example, the hardness of the object OM, the positional relationship of multiple objects OM with respect to the shaft 204, etc. When such an elastic load acts on the shaft 204, as shown in FIG. 13B , the pressure value 125 obtained depending on each position tends to increase or decrease. Note that FIG. 13B illustrates a case in which the pressure value 125 increases as the shaft 204 advances. However, the load characteristics are not limited to this example. Depending on the contact relationship between the shaft 204 and the object OM, the load characteristics may tend to, for example, decrease the pressure value 125 as the shaft 204 advances, or increase after the pressure value 125 decreases. Therefore, the control device 1 may calculate the gradient of the pressure with respect to the position using the pressure value 125 obtained according to each position, and may acquire the calculated gradient as the load characteristic (e.g., spring characteristic, hardness, etc.). The control device 1 may further estimate the type of the contacting object OM from the obtained load characteristic.

[0138] 12A and 12B , the fluid pressure actuator 20 is operated in a harsh environment where the use of sensors is unsuitable, and a camera is used to observe the environment of the driving range of the moving parts, including the fluid pressure actuator 20. In such a situation, dust, radiation, and the like may cause noise in the camera image, making it difficult to clearly observe the environment of the driving range. Furthermore, as illustrated in FIGS. 12A and 12B , the driving parts may not be observed due to environmental conditions, such as the shaft 204 being inserted into a hole. In such a case, by using the above-described method to estimate the characteristics of the load acting on the shaft 204 of the fluid pressure actuator 20 (the moving element 2M of the fluid pressure actuator 2), the status of the fluid pressure actuator 20 (the fluid pressure actuator 2) can be grasped even in situations where observation of the driving range is limited.

[0139] In one example, in the actuator system AS5, the control device 1 may control the positions of the pistons (5103, 5203) of the flow rate measurement units (51, 52) so as to not fix the piston 5103 of the flow rate measurement unit 51 and to fix the piston 5203 of the flow rate measurement unit 52 until the shaft 204 comes into contact with a given object OM and a load is applied to the shaft 204, thereby preventing a large driving force from being transmitted to the shaft 204. After detecting that the object OM has come into contact with the shaft 204 due to the application of a load to the shaft 204, the control device 1 may estimate the characteristics of the object OM using the above-described method. The control device 1 may determine whether or not a large driving force may be applied to the object OM based on the estimated characteristics. Then, if it is determined from the estimated characteristics that a large driving force may be applied to the object OM, the control device 1 may switch the status of the position control so that the piston 5103 of the flow rate measurement unit 51 is fixed and the piston 5203 of the flow rate measurement unit 52 is not fixed. As a result, in conjunction with the driving of the master actuator 62, the shaft 204 of the fluid pressure actuator 20 may be driven in the forward direction with a large driving force, and the driving force may be applied to the object OM.

[0140] <4.2> In the above embodiment, when a liquid is used as the fluid, it is ideal that the tube 4 is sealed with the liquid, but there is a possibility that gas may be mixed into the tube 4. Therefore, when a liquid is used as the fluid, driving the fluid pressure actuator 2 while compensating for the deformation of the tube 4 according to the pressure value 125 may be configured by driving the fluid pressure actuator 2 while compensating for the deformation of the tube 4 according to the pressure value 125 and the elasticity of the gas mixed into the tube 4. That is, in step S102 above, the control unit 11 may drive the fluid pressure actuator 2 while further compensating for the elasticity of the gas mixed into the tube 4 in addition to the deformation of the tube 4 according to the acquired pressure value 125.

[0141] Conventionally, liquids are often treated as incompressible fluids. That is, when a liquid is used as the fluid, the behavior of the fluid transmission path (tube 4) is treated as a hydrostatic transmission (HST). The pressures at the inlet and outlet of the tube 4 can be considered to be approximately the same. The inlet of the tube 4 may be the end on the drive unit 3 or flow rate measurement unit 5 side, and the outlet of the tube 4 may be the end on the fluid pressure actuator 2 side. On the other hand, if gas is mixed into the fluid transmission path, the fluid in the tube 4 may become compressible due to the elasticity of the gas. This may cause the behavior of the tube 4 to differ from when the tube 4 is sealed in a completely filled state with liquid. Compensating for the elasticity of the gas mixed into the tube 4 may compensate for the difference due to the elasticity of the mixed gas. Although it is difficult to measure the amount of mixed gas, the bulk modulus of a liquid mixed with gas can be estimated by calibration, as shown in the experimental example described below. By using this bulk modulus, the difference due to the elasticity of the gas (such as the amount of change in volume of the tube 4) can be estimated from the pressure inside the tube 4. According to this modification, by further compensating for the elasticity of the mixed gas as well as the deformation of the tube 4, it is possible to expect even more appropriate control of the fluid pressure actuator 2.

[0142] Note that the control scheme of the fluid pressure actuator 2 is not particularly limited and may be determined appropriately depending on the embodiment, as long as it includes a term that compensates for the elasticity of the gas mixed in according to the pressure value 125 inside the tube 4. As an example, similar to FIG. 8 above, when assuming a situation in which the actuator system AS1 of FIG. 3 is used as the actuator system AS, water is used as the fluid, and PID control is used for position control of the piston 203 in the fluid pressure actuator 20, the compensation function H (Equation 2) of the tube 41 may be replaced by the following Equation 10, and the volume change amount ΔV of the tube 41 may be ｔ Equations 8 and 9 may be replaced with the following equation 11.

[0143]

[0144] K ｆｌｕｉｄ denotes the bulk modulus of the gas-mixed liquid, and K ｔｕｂｅ represents the bulk modulus based on the structural elasticity of the tube 41. Ａｃｔ indicates the cross-sectional area of ​​the internal space (201, 202) of the cylinder tube 200 in the fluid pressure actuator 20. ｔ０ indicates the initial volume of the tube 41. p indicates the value 125 of the pressure inside the tube 41. The value of p can be obtained from the pressure gauge 411. ｔ０ ×p×(1 / K ｔｕｂｅ ) is the ΔV in Equation 2 ｔ (p, R, t, L, E, ν). Therefore, "V ｔ０ ×p×(1 / K ｔｕｂｅ ) is the ΔV ｔ Alternatively, the bulk modulus K of the tube 41 may be calculated. ｔｕｂｅ Is, K ｆｌｕｉｄ The bulk modulus K ｔｕｂｅ The calculation model of the bulk modulus K may have the length and diameter of the tube 41 as parameters. ｔｕｂｅ The calculation model of K may be appropriately configured so that it is inversely proportional to the length of the tube 41 and proportional to the square of the diameter of the tube 41. ｆｌｕｉｄcan be defined by the following equation 12:

[0145]

[0146] K ｗ indicates the bulk modulus of pure water. ０ indicates atmospheric pressure (initial pressure). γ indicates the specific heat ratio of the gas. α indicates the volumetric mixing ratio of the gas under atmospheric pressure. K ｗ A known value for the bulk modulus of water may be applied to K. ｗ remains unknown, K ｆｌｕｉｄ may be modeled. ０ The measured value of atmospheric pressure (initial value of pressure) may be applied to . Any value between 1 and 1.4 may be applied to γ. In the right-hand side of Equation 12, since the amount of gas mixed in is unknown, α (volume mixing ratio) may be unknown. However, the value of α (and K ｗ Even if the value of K is unknown, as will be shown in the experimental example below, system identification (calibration) based on the pressure response can be used to determine K as a function of p. ｆｌｕｉｄ The obtained K can be modeled. ｆｌｕｉｄ to Equation 11, the compensation function H(p) of Equation 10 can be calculated. As a result, by the control scheme of FIG. 8, it is possible to drive the fluid pressure actuator 20 while compensating for the deformation of the tube 41 and the elasticity of the gas mixed in the tube 41 according to the pressure value 125 in the tube 41. Furthermore, it is possible to estimate the position of the mover (piston 203 and shaft 204) of the fluid pressure actuator 20 while controlling the operation of the fluid pressure actuator 20. By compensating for the deformation of the tube 41 and the elasticity of the gas mixed in when estimating the position of the mover, it is possible to expect an improvement in the estimation accuracy of the position of the mover. As a result, it is also possible to expect an improvement in the controllability of the fluid pressure actuator 20. Note that the above Equation 12 is expressed by K ｆｌｕｉｄ The model of the bulk modulus due to a mixture of gas and liquid is not limited to Equation 12. In another example, the model of the bulk modulus due to a mixture of gas and liquid may be configured by an empirical response function to pressure, a regression equation, a machine learning model (such as a neural network), or a function equation using a known physical model.

[0147] <4.3> In the above embodiment, the pressure gauges (pressure gauge 411, pressure gauge 421) may be disposed on the inlet side of the tube 4 (tube 41, tube 42). The inlet of the tube 4 may be connected to the drive unit 3 or the flow rate measurement unit 5, and the outlet of the tube 4 may be connected to the fluid pressure actuator 2. This makes it possible to identify the state of the fluid pressure actuator 2 and control the driving of the fluid pressure actuator 2 according to the identified state without providing sensors inside or around the fluid pressure actuator 2. In one example, the fluid pressure actuator 2 can be configured sensorless. However, pressure propagation occurs within the tube 4 as the fluid moves. When pressure propagation occurs, pressure fluctuations occur within the tube 4, which can result in a pressure distribution. That is, a pressure difference can occur between the inlet and outlet of the tube 4. The longer the tube 4, the more likely this pressure distribution can occur within the tube 4. This pressure distribution can result in a difference in deformation on the tube 4. For example, when the hydraulic actuator 2 is connected to a robotic device and the robotic device is pushed back by something, a difference in deformation may occur, such as a portion near the outlet of the tube 4 close to the hydraulic actuator 2 expanding and a portion near the inlet of the tube 4 contracting. Compensating for the deformation of the tube 4 may include compensating for such a difference in deformation occurring on the tube 4.

[0148] The pressure distribution in the tube 4 may be appropriately estimated from the measurement value (pressure value 125) of a pressure gauge arranged on the inlet side of the tube 4. A known method such as Non-Patent Document 1 may be adopted as a method for estimating the pressure distribution. By modifying the compensation function H so that compensation for the deformation of the tube 4 is estimated not only from the measurement value of the pressure gauge but also from the pressure distribution, differences in deformation occurring on the tube 4 may be appropriately compensated for. In one example, similar to FIG. 8 above, assuming a situation in which the actuator system AS1 of FIG. 3 is adopted as the actuator system AS, water is used as the fluid, the form <4.2> in which the elasticity of the mixed gas is further compensated for is adopted, and PID control is adopted for position control of the piston 203 in the fluid pressure actuator 20, the compensation function H (Equation 2) of the tube 41 may be replaced by the following Equation 13, and the volume change amount ΔV of the tube 41 may be calculated as follows: ｔ is the ΔV in the following equation 14 ｔｔｏｔａｌ may be replaced by

[0149]

[0150] A ｔ indicates the cross-sectional area of ​​the tube 41. ｔ The above formula 4 may be applied to K. L represents the length of the tube 41. ｆｌｕｉｄ represents the bulk modulus of the liquid containing the gas. As in <4.2> above, K ｆｌｕｉｄ The model obtained by calibration may be applied to p ０ indicates the reference pressure (atmospheric pressure). Ａ indicates an estimated value of the pressure near the outlet of the tube 41. p is a pressure value 125 measured by a pressure gauge 411 arranged near the inlet of the tube 41. When it is assumed that the tube 41 is divided into two regions, a region near the inlet and a region near the outlet, the estimated value of the pressure near the outlet of the tube 41 (p Ａ ) can be estimated by calculation based on a fluid dynamics model including the compressibility of the fluid, given by the following Equation 15 shown in Non-Patent Document 1:

[0151]

[0152] R represents the gas constant. T represents the temperature. (R × T) in Equation 15 is the bulk modulus (K ｆｌｕｉｄ ) can be replaced by V. This allows reformulating Equation 15 into a linear model that does not depend on physical constants. ｔｔｏｔａｌ indicates the total volume of the fluid pressure actuator 20 and the area on the outlet side of the tube 41. ｉｎ indicates the amount of water flowing into the tube 41. ｉｎ is the position of the piston 5103 (x Ｏｐ ) (measurement value 127). For example, x Ｏｐ If the reference position of is 0, m ｉｎ is "x Ｏｐ ×S Ｏｐ " can be calculated as γ １ denotes the specific heat ratio of the gas in the tube 41 in the first region on the inlet side of the tube 41. γ ２ denotes the specific heat ratio of the gas in the tube 41 in the second region on the outlet side of the tube 41. γ １ and γ ２ Any value between 1 and 1.4 may be applied to γ １ and γ ２ may be the same value or may be different values. Ａ indicates the volume change rate of the fluid pressure actuator 20 (fluid pressure cylinder). Furthermore, equations (12a) to (12d) in Non-Patent Document 2 may be applied to calculations based on a fluid dynamics model in the inlet region of the tube 41.

[0153] From the reformulated Equation 15, p Ａ Estimate the estimated p ＡBy substituting into Equation 14, the compensation amount (Equation 13) for the deformation of the tube 41 due to the pressure distribution can be calculated. As a result, the control scheme of FIG. 8 makes it possible to drive the fluid pressure actuator 20 while compensating for the difference in deformation occurring on the tube 41. Furthermore, while controlling the operation of the fluid pressure actuator 20, it is possible to estimate the position of the mover (piston 203 and shaft 204) of the fluid pressure actuator 20. By compensating for the difference in deformation occurring on the tube 41, it is expected that the accuracy of estimating the position of the mover will be improved. As a result, it is also expected that the controllability of the fluid pressure actuator 20 will be improved.

[0154] As described above, when a liquid is used as the fluid, the behavior of the fluid transmission path has traditionally been treated as static because the liquid is an incompressible fluid. However, when considering deformation of the tube 4 (which serves as the transmission path) (and even the incorporation of gas into the tube 4), the liquid in the tube 4 behaves similarly to a compressible fluid. In this modification, even when a liquid is used as the fluid, the dynamics of the transmission path (tube 4), which was traditionally treated as static, can be ensured by compensating for differences in deformation occurring on the tube 4, as in the calculations of Equations 13 to 15 above. This is expected to improve the accuracy of estimating the position of the mover 2M in the fluid pressure actuator 2. As a result, improved controllability of the fluid pressure actuator 2 can also be expected.

[0155] The above formula 15 is an example of a continuous model formula relating to the pressure distribution and volume change in the tube 41 (tube 4). The number of divisions into which the tube 41 (tube 4) is divided is not limited to two, and may be three or more. The number of divisions may be increased appropriately depending on the length of the tube 41 (tube 4). When the number of divisions is increased to three or more, p Ａ The calculation formula of may be derived appropriately by further discretizing the tube 41 (tube 4) based on formula 15 and formulas (12a) to (12d) of Non-Patent Document 2.

[0156] Furthermore, the control device 1 may divide the tube 41 (tube 4) into multiple sections and estimate the pressure distribution for each section based on the diameter of the tube 41 (tube 4). For example, according to equation (4) in Non-Patent Document 1, pressure loss is inversely proportional to the square of the tube inner diameter. It is known that pressure loss decreases as the tube expands and the inner diameter increases. Therefore, in the above embodiment, the control device 1 may calculate the inner diameter after expansion of the section in which the pressure gauge 411 is located (e.g., the first section from the inlet side) based on the pressure value 125 of the pressure gauge 411. The control device 1 may sequentially estimate the pressure value and inner diameter of the next section (section (k+1)) from the calculated inner diameter of the section (section (k)). The control device 1 may then calculate the pressure loss for each section based on the estimated pressure value and inner diameter, and compensate for the calculated pressure loss. This makes it possible to compensate for the pressure loss for each section. Furthermore, because the expansion amount for each section can be estimated, it is expected that the accuracy of estimating the deformation amount of the entire tube 41 (tube 4) will be improved, and therefore the accuracy of estimating the position of the mover (mover 2M) of the fluid pressure actuator 20 (fluid pressure actuator 2) will also be improved. In this way, by estimating both the pressure loss and the expansion distribution while dynamically compensating for the deformation of the tube 41 (tube 4), it is expected that the accuracy of estimating the position and generated force of the mover (mover 2M) will be improved even if the fluid pressure actuator 20 (fluid pressure actuator 2) is sensorless, and as a result, it is possible to build a more robust control system.

[0157] 3 to 7, a fluid pressure cylinder is used as the fluid pressure actuator 2 (fluid pressure actuator 20). However, as described above, the type of fluid pressure actuator 2 does not have to be limited to a fluid pressure cylinder. Other types of fluid pressure actuators, such as fluid pressure artificial muscles, may be used as the fluid pressure actuator 2. When other types of fluid pressure actuators are used as the fluid pressure actuator 2, the control scheme of FIG. 8 may be modified as appropriate.

[0158] Fig. 14 shows a schematic diagram of another example of a control scheme when a fluid pressure artificial muscle is used as the fluid pressure actuator 2. In the example of Fig. 14, a situation is assumed in which the actuator system AS1 of Fig. 3 is used as the actuator system AS, the fluid pressure actuator 20 is replaced with a McKibben type fluid pressure artificial muscle, and PID control is used for position control of the operating end of the fluid pressure artificial muscle. ｔＡｃｔ indicates the target position of the operating end of the fluid pressure artificial muscle. The target position may be determined appropriately. As in the control scheme of FIG. 8, x Ｏｐ indicates the value of the current position of the piston 5103 measured by the measurement sensor 512 of the flow rate measurement unit 51. Unlike a fluid pressure cylinder, the cross-sectional area of ​​a fluid pressure artificial muscle is not constant. Therefore, the compensation function H ２ may be defined in the dimension of the volume as in Equation 16 below: ２ Using this, the fluid volume V supplied to the fluid pressure artificial muscle Ａｉｎ (Estimated value) may be given by the calculation of Equation 17 below.

[0159]

[0160] As in the above embodiment, S Ｏｐ indicates the cross-sectional area of ​​the internal space (5101, 5102) of the cylinder tube 5100 in the flow rate measuring unit 51. ｔ may be calculated using the above-mentioned formulas 8, 9, 11, etc. When compensating for the pressure distribution in the tube 41, ΔV ｔ is the above ΔV ｔｔｏｔａｌ may be replaced by W Ａ is ΔV Ａｉｎ After being replaced by ΔV ｔｔｏｔａｌ may be applied to Equation 16.

[0161] The internal volume of a fluid pressure artificial muscle is determined by the contraction rate ε (= 1-L / L ０ ) and deforms nonlinearly depending on the position of the working end (x ｅＡｃｔ ) In the following, for the sake of convenience, the length L of the fluid pressure artificial muscle corresponds to the position of the operating end (x ｅＡｃｔ ) and treated as equal. ０indicates the initial value of the length of the fluid pressure artificial muscle. ０ The internal volume V of the fluid pressure artificial muscle during contraction may be given as appropriate. Ａ (ε) can be expressed by the following equation 18.

[0162]

[0163] V Ａ０ indicates the initial internal volume of the fluid pressure artificial muscle. θ ０ indicates the initial value of the braid angle. Ａ０ and θ ０ may be given as appropriate. The fluid volume (ΔV Ａｉｎ ) can be defined as a function of the shrinkage ratio ε by the following equation 19:

[0164]

[0165] ΔV Ａｉｎ can be calculated using Equation 17. Therefore, by back-calculating Equation 19, ΔV Ａｉｎ Therefore, the inverse function of Equation 19 (ΔV Ａｉｎ －１ () is derived. ２ θ ０ By substituting for the constant C, the following equation 20 can be obtained.

[0166]

[0167] When the shrinkage ratio ε is assumed to be a small value (for example, 0.3 or less), the following approximate equation, Equation 21, can be obtained from Equation 20. Then, by solving the quadratic equation of Equation 21 for ε, the following equation, Equation 22, can be obtained.

[0168]

[0169] On the other hand, when approximation is not used, Equation 20 can be expanded to Equation 23 below.

[0170]

[0171] Using Cardano's formula, we can analytically solve the cubic equation in Equation 23 for ε to obtain ΔV ＡｉｎHereinafter, the calculation formula for ε obtained by solving Equation 23 using Cardano's formula will also be referred to as the "analytical formula."

[0172] The control device 1 (control unit 11) calculates ΔV Ａｉｎ The control device 1 (control unit 11) may calculate the obtained ΔV Ａｉｎ The shrinkage factor ε may be calculated from the following equation. The approximation formula of Equation 22 can be beneficial in situations where the shrinkage factor ε needs to be easily estimated, such as in real-time control. When ε is small, the error in ε calculated by Equation 22 also becomes small, making the approximation formula of Equation 22 valid as a practical estimation method. On the other hand, compared to the approximation formula of Equation 22, the analytical formula obtained by solving Equation 23 can be expected to provide a more accurate estimate of the shrinkage factor ε. Therefore, by selectively using the approximation formula of Equation 22 and the analytical formula obtained by solving Equation 23 depending on the application, it is possible to expect both responsiveness and accuracy in the process of estimating the shrinkage factor ε.

[0173] The control device 1 (control unit 11) substitutes the calculated contraction rate ε into the following equation 24 to obtain the current position (x ｅＡｃｔ ) may be estimated.

[0174]

[0175] The current position of the operating end of the fluid pressure artificial muscle (x ｅＡｃｔ ), similar to the control scheme of FIG. 8, the control device 1 (control unit 11) estimates the target position (x ｔＡｃｔ ) and the current position (x ｅＡｃｔ The control device 1 (control unit 11) may perform PID control of the operating end position of the fluid pressure artificial muscle in accordance with the calculated deviation e.

[0176] If the pressure value and contraction rate ε of the fluid pressure artificial muscle can be specified, the force (contraction force) output from the fluid pressure artificial muscle can be estimated from the specified pressure value and contraction rate ε. The contraction rate ε may be estimated by the above calculation. The pressure value of the fluid pressure artificial muscle may be the pressure value 125 measured by the pressure meter 411 placed near the inlet of the tube 41, or may be the pressure value p estimated by the reformulated Equation 15. Ａ If the contractile force of a fluid-pressure artificial muscle can be estimated, the estimated contractile force can be used to control the force of the fluid-pressure artificial muscle when driving the fluid-pressure artificial muscle. A known method such as that described in Patent Document 2 may be used as the force control method.

[0177] A fluid pressure artificial muscle may have a configuration in which the internal volume is reduced by inserting a hollow cylinder as a nest structure inside the fluid pressure artificial muscle. When this configuration is adopted, the contraction rate ε is calculated by multiplying the reduced volume (V Ａｓｕｂ ) is calculated by subtracting the effective volume (V Ａ１ =V Ａ０ -V Ａｓｕｂ ) may be redefined using the formula. The above equations are based on the assumption that the working end is configured to be displaced. However, the type of fluid pressure artificial muscle is not limited to this example. In another example, the fluid pressure artificial muscle may be configured to have a curved working end. In this case, a correspondence relationship between the contraction rate ε and the degree of curvature may be appropriately given, and the state of the working end may be estimated based on the given correspondence relationship. Furthermore, multiple fluid pressure artificial muscles may be arranged in an antagonistic manner. The stiffness of the joint can be adjusted by differentially controlling the contraction rate ε of each fluid pressure artificial muscle. With regard to the control portion of the fluid pressure artificial muscle, the present disclosure may be used in combination with various known techniques.

[0178] <4.5> Furthermore, in the above embodiment, the calculation model of Equations 5 to 9 may be replaced with the calculation model shown in Equations 25 to 30 below.

[0179]

[0180] σ ｒ denotes the radial stress of the tube 4 (tube 41), and σ θ indicates the stress in the circumferential direction of the tube 4 (tube 41), and σ ｚ indicates the stress in the longitudinal direction (axial direction) of the tube 4 (tube 41). p indicates the pressure inside the tube 4 (tube 41), and the value (pressure value 125) measured by the pressure gauge (pressure gauge 411) may be input. p ０ indicates atmospheric pressure. ｉ indicates the inner radius (initial value before deformation) of the tube 4 (tube 41), and r ｏ indicates the outer radius (initial value before deformation) of the tube 4 (tube 41). ｉ indicates the change in the inner radius, and Δr ｏ indicates the amount of change in the outer radius. 1 indicates the length of the tube 4 (tube 41). E indicates the Young's modulus of the material of the tube 4 (tube 41). ν indicates the Poisson's ratio. ΔV ｔ indicates the volume change of the tube 4 (tube 41). According to this calculation model, even if the material properties of the tube 4 (tube 41) are unknown, the deformation of the tube 4 (tube 41) can be modeled by calibration. Furthermore, this calculation model includes parameters for the inner radius, outer radius, and length of the tube 4 (tube 41). Therefore, even if the tube conditions differ between calibration and operation, the calculation model obtained during calibration can be applied during operation. This eliminates the need to perform calibration every time the tube is changed, which is expected to reduce the effort required for calibration.

[0181] §5 Experimental Examples The following experiments were conducted to verify the effectiveness of the above-described embodiments, but the present disclosure is not limited to the following examples.

[0182] [First Experimental Example] Figure 15 shows the configuration of the system used in the first experimental example. First, the system shown in Figure 15 was prepared to verify the deformation of a flexible tube. Water was used as the fluid. A 1000 mm nylon tube (N2-4-4x2.5, Nitta Corporation) was used as the connecting tube. In the first experimental example, one end of the connecting tube was not connected to the fluid pressure actuator and was sealed to prevent water leakage. The connecting tube was extended in a straight line (curvature 0.00). The same tube as the connecting tube was also used for the piping. A pressure sensor was placed between the pump and the fluid pressure cylinder (flow measurement unit). An optical encoder was used as the measurement sensor for the flow measurement unit. The pressure sensor and optical encoder were connected to a computer via a multifunction board. Then, while gradually increasing pressure with a manual pump, the pressure in the piping was measured with the pressure sensor, and the position of the fluid pressure cylinder shaft was measured with the optical encoder.

[0183] FIG. 16 shows the measurement results of the shaft position and pressure in the first experimental example. When the tube does not deform, the shaft position and pressure have a constant proportional relationship. In contrast, in the first experimental example, deformation of the connecting tube occurred when the piping pressure was around 0.5 MPa. This caused the shaft position to change even though the pressure value hardly changed. This result shows that tube deformation can lead to a decrease in the accuracy of controlling the drive of the fluid pressure actuator.

[0184] Second Experimental Example Next, a system having a configuration similar to that of the actuator system AS1 shown in Fig. 3 was prepared. As in the first experimental example, a 20,000 mm (20 m) nylon tube (N2-4-4x2.5, Nitta Corporation) was used as the tube.

[0185] Under the conditions of the example, the position of the shaft of the fluid pressure actuator was controlled while compensating for the deformation of the tube using the compensation function H in accordance with the control scheme of Figure 8. The target position was set to 20 mm. Experimental values ​​for the volume change in the tube were obtained in advance while gradually increasing the pressure inside the 20 m tube. The volume change ΔV in the compensation function Hｔ was set to a third-order polynomial (four degrees of freedom) of p, and the values ​​of each parameter of the third-order polynomial were fitted using the experimental values ​​obtained. This gave the compensation function H.

[0186] On the other hand, the conditions of the comparative example were the same as those of the experimental example, except that compensation for tube deformation using the compensation function H was omitted. When controlling the operation under the conditions of the example and comparative example, a scale was placed on the shaft of the fluid pressure actuator, and the position of the shaft was measured by an optical encoder, just like in the flow rate measurement unit.

[0187] FIG. 17A shows the results of position control under the conditions of the comparative example. FIG. 17B shows the calculation results of the error between the shaft position (estimated value) of the fluid pressure actuator estimated from the measurement sensor of the flow measurement unit and the actual shaft position (measured value) of the fluid pressure actuator under the conditions of the comparative example. FIG. 18A shows the results of position control under the conditions of the example. FIG. 18B shows the calculation results of the error between the shaft position (estimated value) of the fluid pressure actuator estimated from the measurement sensor of the flow measurement unit and the actual shaft position (measured value) of the fluid pressure actuator under the conditions of the example. As shown in FIGS. 17A and 17B, under the conditions of the comparative example, an error occurred in the estimation of the shaft position due to not compensating for tube deformation, and the shaft position of the fluid pressure actuator was controlled to a position deviated from the target position of 20 mm. On the other hand, as shown in FIGS. 18A and 18B, under the conditions of the example, compensation for tube deformation was able to eliminate the error in the estimation of the shaft position, and as a result, the shaft position of the fluid pressure actuator was able to be controlled to the target position of 20 mm. These results show that when a flexible tube is used, it is possible to suppress a decrease in the control accuracy of the fluid pressure actuator by compensating for the deformation of the tube according to the pressure value. These results show that the above embodiment improves the maneuverability and enables the fluid pressure actuator to be controlled appropriately.

[0188] [Third Experimental Example] In the third experimental example, K is calculated as a function of p by system identification (calibration) based on pressure response.ｆｌｕｉｄ We verified whether we could model the above. Specifically, a system with a configuration similar to that of the actuator system AS1 shown in Figure 3 was prepared. A 10,000 mm nylon tube (N2-4-4x2.5, Nitta Corporation) was used as the tube for the first condition. (1) Water was filled into the system and the air was removed. (2) With the fluid pressure actuator (fluid pressure cylinder) removed, the end of the tube (the fluid pressure cylinder side) was sealed with a coupler. (3) The valve was opened to gradually move the moving element of the flow measurement unit toward the fluid pressure actuator, thereby increasing the pressure inside the tube. (4) While the pressure inside the tube was increasing, the pressure inside the tube was measured with a pressure gauge, and the change in the volume of the tube was also measured. (5) Using the measured values ​​of the pressure and volume change inside the tube, least-squares error curve fitting was performed to find K as a function of p from Equations 11 and 12. ｆｌｕｉｄ WoK ｔｕｂｅ The calculation model used the following equations: Equations 25 to 30. Based on the material properties of conventionally used nylon, the value of the Poisson's ratio ν of the tube was set to 0.4. The value of the specific heat ratio γ was set to 1.0. K ｔｕｂｅ The tube length and diameter conditions were applied to the first condition. Using the obtained model, the volume change was calculated from the measured pressure inside the tube. Steps (1) to (4) were also performed under different tube conditions. Under the second condition, a 20,000 mm nylon tube (N2-4-4x2.5, Nitta Corporation) was used. Under the third condition, a 50,000 mm nylon tube (N2-4-4x2.5, Nitta Corporation) was used. Under the fourth condition, a 100,000 mm nylon tube (N2-4-4x2.5, Nitta Corporation) was used. Under the fifth condition, a 20,000 mm nylon tube (N2-4-8x6, Nitta Corporation) with a different diameter than under the second condition was used. Then, using the model obtained under the first condition, the volume change was calculated from the measured pressure inside the tube under each of the second to fifth conditions.

[0189] Figure 19 shows the measured values ​​(solid lines) and the estimated values ​​(dotted lines) by the model for each condition in the third experimental example. As shown in Figure 19, a model that fits the measured values ​​for the first condition was obtained. From this result, it was found that by system identification (calibration) based on the pressure response, K can be calculated as a function of p. ｆｌｕｉｄ (and K ｔｕｂｅ ) could be modeled. Furthermore, as shown in Figure 19, the model obtained under the first condition was able to accurately estimate the measured values ​​under other conditions. From this result, it was estimated that the mixing of air (gas) occurs around the tube, such as the connection between the tube and each component, regardless of the attributes (length, thickness) of the tube. From this, it was found that a model obtained under tube conditions different from those during operation can also be applied during operation. In other words, it was possible to estimate K under any condition. ｆｌｕｉｄ (and K ｔｕｂｅ It was found that by modeling the above, it is possible to accurately estimate the position of the moving element of the fluid pressure actuator using the obtained model, regardless of the type of tube used during operation.

[0190] [Fourth Experimental Example] In the fourth experimental example, it was verified whether the elasticity of the mixed gas could be further compensated. Specifically, a system having a configuration similar to that of the actuator system AS1 shown in FIG. 3 was prepared. As in the first experimental example, a 10,000 mm nylon tube (N2-4-4x2.5, Nitta Corporation) was used as the tube. ｆｌｕｉｄ and K. ｔｕｂｅThe model obtained in the third experimental example was used. According to the control scheme shown in Figure 8, the position of the moving element of the fluid pressure actuator was controlled while compensating for the deformation of the tube and the elasticity of the mixed gas using the compensation function H of Equation 10. Initially, the moving element was stopped at the 0 mm position, and a target position was set at the start of the graph. The target position (target value) was set to 30 mm. While the position control was being performed, the position of the moving element of the fluid pressure actuator was measured using a measurement sensor. This resulted in an actual measurement value of the moving element position in the fluid pressure actuator. Furthermore, the position of the moving element of the flow measurement unit was measured using a measurement sensor, and the pressure in the tube was measured using a pressure gauge. Furthermore, a low-pass filter was used to smooth the actual measurement value of the pressure in the tube (measurement value obtained by the pressure gauge). Using the calculation formulas of Equation 1 and Equation 10 above, the position of the moving element of the flow measurement unit was estimated from the measured values ​​of the moving element position and pressure of the flow measurement unit. This resulted in an estimated value of the moving element position in the flow measurement unit. Then, the actual measured value and the estimated value of the position of the mover in the flow rate measuring unit were compared.

[0191] Fig. 20A shows the actual measured and estimated values ​​of the position of the mover of the fluid pressure actuator in the fourth experimental example. Fig. 20B shows the actual measured values ​​of the pressure inside the tube in the fourth experimental example. As shown in Fig. 20A, there was almost no error between the actual measured and estimated values ​​of the position of the mover of the fluid pressure actuator. From this result, it can be seen that the K obtained by calibration ｆｌｕｉｄIt was found that the elasticity of the mixed gas can be appropriately compensated for by using this model. It was also found that further compensation for the elasticity of the mixed gas can improve the accuracy of estimating the position of the moving element in the fluid pressure actuator, thereby enabling the fluid pressure actuator to be driven more appropriately. Furthermore, as shown in FIG. 20B , in the fourth experimental example, position control was performed with the moving element of the fluid pressure actuator stopped midway rather than stopping it at the end of its range of motion. In this case, the rigidity of the moving element of the fluid pressure actuator (i.e., the impedance at the tip) was low. It was also found that the position of the moving element of the fluid pressure actuator can be accurately estimated from information obtained on the flow measurement unit, even though information on the force acting on the moving element of the fluid pressure actuator was not provided.

[0192] REFERENCE SIGNS LIST 1...control device, 11...control section, 12...storage section, 13...external interface, 14...input device, 15...output device, 16...drive, 81...control program, 91...storage medium, 111...information acquisition section, 112...operation control section, AS...actuator system, 2...fluid pressure actuator, 3...drive section, 4...tube

Claims

1. A control device comprising a control unit configured to: acquire a pressure value in a flexible tube connected to a fluid pressure actuator, the tube supplying and discharging fluid to the fluid pressure actuator; and drive the fluid pressure actuator while compensating for deformation of the tube in accordance with the acquired pressure value.

2. The control device according to claim 1, wherein the tube connects the fluid pressure actuator and a flow rate measurement unit, the flow rate measurement unit is provided with a measurement sensor configured to measure the amount of fluid flowing into the tube from the flow rate measurement unit, the control unit is further configured to obtain a measurement value of the amount of fluid flowing into the tube from the flow rate measurement unit from the measurement sensor, and driving the fluid pressure actuator is configured by driving the fluid pressure actuator in accordance with the obtained measurement value.

3. The control device according to claim 2, wherein the flow rate measurement unit has a movable element that is driven in response to driving of the movable element of the fluid pressure actuator, and driving the fluid pressure actuator while compensating for deformation of the tube includes estimating the position of the movable element of the fluid pressure actuator while compensating for deformation of the tube in accordance with the position of the movable element of the flow rate measurement unit.

4. The control device according to claim 1, wherein the fluid is a liquid.

5. The control device according to claim 4, wherein driving the fluid pressure actuator while compensating for deformation of the tube according to the pressure value comprises driving the fluid pressure actuator while compensating for deformation of the tube according to the pressure value and the elasticity of gas mixed in the tube.

6. The control device according to claim 4, wherein the tube is made of nylon.

7. The control device according to claim 4, wherein the diameter of the tube is 3 mm or less, and the length of the tube is 20 m or more.

8. A control method executed by a computer, the control method including: acquiring a pressure value in a flexible tube connected to a fluid pressure actuator, the tube supplying and discharging fluid to the fluid pressure actuator; and driving the fluid pressure actuator while compensating for deformation of the tube in accordance with the acquired pressure value.

9. A control program for causing a computer to execute a control method, the control method including: acquiring a pressure value within a flexible tube connected to a fluid pressure actuator, the tube supplying and discharging fluid to the fluid pressure actuator; and driving the fluid pressure actuator while compensating for deformation of the tube in accordance with the acquired pressure value.

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