Control device and control method for work device

Abstract

To keep control accuracy even when continuously used for a long period of time.SOLUTION: A control device 100 includes: a liquid pressure transmission tube 108 that transmits pressure via liquid to a piston 902 that drives a joint portion 901 of a work device (robot 900); pressure application means (pump 110) that applies the pressure to the liquid; a pressure gauge 104 that measures a pressure value of the liquid; a flow meter 103 that measures a flow rate value of the liquid; a tube deformation correction unit 106 that calculates a flow rate fluctuation value of the liquid according to the pressure value of the liquid using a tube deformation parameter prepared in advance and corrects the flow rate value of the liquid; a joint angle estimation unit 105 that estimates a joint angle from the corrected flow rate value, and a parameter calibration unit (tube deformation parameter calibration unit 120) that calculates a current tube deformation amount from a measurement value of the flow rate value before start of pressure application and a measurement value of the flow rate value after the end of the pressure application and calibrates the tube deformation parameter.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a control device for a working device and a control method.

Background Art

[0002] Conventionally, a remote control system has been provided in which a robot (working device) is remotely operated to perform work in a place where it is difficult for a human to directly perform work. Examples of work in a place where it is difficult for a human to directly perform work include work in a harsh environment such as a high radiation dose. As an example, there are decommissioning work at nuclear power plants and work in outer space. When trying to make a robot work in such a harsh environment, precise electronic devices such as a stepping motor used for driving the robot and a semiconductor sensor used for control are vulnerable to radiation, so it is difficult to use them for a long time. Therefore, it has been desired to provide a remote control system that does not use electronic devices such as motors and sensors as much as possible. Therefore, a remote control system has been proposed in which a piston is driven by a hydraulic system and the joint part of the robot is operated in conjunction with the piston. In this remote control system, a liquid is sent from a control device to a piston through a long tube, and the control device manages the flow rate (liquid volume) of the sent liquid to control the opening and closing angle (joint angle) of the joint part of the robot. Such a remote control system can install a control device in a remote place that is a safe environment. In addition, the number of electronic devices such as motors and sensors can be reduced.

[0003] In a remote control system, a flexible resin tube is used to freely operate the robot in the working space. However, resin has the property of causing elastic deformation or viscous deformation when receiving the pressure of a liquid. Elastic deformation immediately returns to its original shape as soon as the pressure is relieved. However, viscous deformation takes time to recover, and there is also a possibility that it will not return to its original shape due to remaining plastic deformation. In order to accurately control the operation of the robot, the control device corrects the flow rate (liquid volume) of the liquid sent to the piston in consideration of such characteristics of the tube.

[0004] In relation to this type of technology, for example, there is something disclosed in Patent Document 1. Patent Document 1 discloses a technology that stores in advance the amount of deflection due to creep deformation of an arm in association with the cumulative time, measures the actually operated cumulative time, and corrects a robot model based on the stored amount of deflection.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in the technology disclosed in Patent Document 1, for example, when an unexpected pressure is applied or a pressure measurement error occurs, an error occurs between the previously stored amount of deflection and the amount of deflection due to the cumulative time. In this case, the error accumulates over time, and the correction deviation expands. Therefore, when the robot (working device) is used continuously for a long time, it is difficult to maintain the control accuracy. Especially in a harsh environment such as a high radiation dose, errors are likely to accumulate and correction deviations are likely to expand. Therefore, it is very difficult to maintain the control accuracy especially in a harsh environment such as a high radiation dose.

[0007] The present invention has been made to solve the above-described problems, and a main object thereof is to provide a control device for a working device and a control method that can maintain control accuracy even when used continuously for a long time.

Means for Solving the Problems

[0008] To achieve the above object, the present invention provides a control device for a working device, comprising: a hydraulic transmission tube that transmits pressure to a piston for driving a joint portion of the working device via a liquid; a pressure application means for applying pressure to the liquid; a pressure gauge for measuring the pressure value of the liquid; a flow meter for measuring the flow rate value of the liquid; a tube deformation correction unit for correcting the flow rate value of the liquid from the pressure value of the liquid using a pre-prepared tube deformation parameter; a joint angle estimation unit for estimating a joint angle from the corrected flow rate value; and a parameter calibration unit for calculating a current tube deformation amount from the measured value of the flow rate value before the start of pressure application and the measured value of the flow rate value after the end of pressure application, and calibrating the tube deformation parameter. Other means will be described later.

Effects of the Invention

[0009] According to the present invention, even when continuously used for a long time, it is possible to provide a control device for a working device that maintains control accuracy, and a control method.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5A

Figure 5B

Figure 6

Figure 7

Figure 8

Best Mode for Carrying Out the Invention

[0011] Hereinafter, with reference to the drawings, embodiments of the present invention (hereinafter referred to as "the present embodiment") will be described in detail. Note that each drawing only schematically shows the invention to such an extent that it can be sufficiently understood. Therefore, the present invention is not limited to only the illustrated examples. Also, in each drawing, common components and similar components are denoted by the same reference numerals, and redundant descriptions thereof are omitted.

[0012] [First Embodiment] [Configuration of Control Device] Hereinafter, with reference to FIG. 1, the configuration of a remote operation system 1000 including a control device 100 according to the first embodiment will be described. FIG. 1 is a schematic configuration diagram of a remote operation system 1000 including a control device 100 according to the first embodiment. The control device 100 is a component that controls the entire operation of the robot 900. The robot 900 is a working device that performs work in various locations. Here, a case where the robot 900 is a working device that performs work in a harsh environment such as a high radiation dose will be described.

[0013] As shown in FIG. 1, the robot 900 has joint portions 901. A plurality of joint portions 901 are provided. The joint portions 901 are driven by the operation of the piston 902 by the pressure (hydraulic pressure) of the liquid sent from the control device 100 via the hydraulic transmission tube 108. Here, a case where the liquid is water and the hydraulic pressure is water pressure will be described. However, the liquid is not limited to water, and various liquid substances such as oil can be used.

[0014] Note that the hydraulic transmission tube 108 is a member that transmits the liquid (water) to which pressure is applied. The hydraulic transmission tube 108 has a long, hollow cylindrical shape. The hydraulic transmission tube 108 is made of a flexible resin. Therefore, the hydraulic transmission tube 108 has the characteristics of not only elastic deformation but also viscous deformation. Elastic deformation and viscous deformation will be described later.

[0015] The control device 100 has a hydraulic transmission tube 108b at the location where the pump 110 and the flow meter 103 are connected. Also, the control device 100 has a hydraulic transmission tube 108a at the location where the flow meter 103 and the piston cylinder 102 are connected.

[0016] The control device 100 includes a control unit 101 that controls the operations of each part of the control device 100. The control unit 101 has an output unit 101a and a warning unit 101b. The control unit 101 realizes these respective functions (in addition to the control unit 100 (output unit 101a, warning unit 101b), the joint angle estimation unit 105, the tube deformation correction unit 106, etc.) by the CPU (Central Processing Unit) executing a program stored in the storage means.

[0017] The output unit 101a is a component that outputs arbitrary information to external devices such as a display unit (input / output device) and an external computer. The output unit 101a outputs, for example, the predicted time when each coefficient value of the creep compliance of the tube deformation parameter exceeds a preset threshold value to an external device. Here, the "predicted time when each coefficient value of the creep compliance of the tube deformation parameter exceeds the threshold value" means the predicted time when the hydraulic transmission tube 108 is considered to be deteriorated. Such a control device 100 can output the predicted time when the hydraulic transmission tube 108 is considered to be deteriorated to an external device.

[0018] The warning unit 101b is a component that outputs a warning to an external device. The warning unit 101b outputs a warning to an external device, for example, when each coefficient value of the creep compliance of the tube deformation parameter exceeds a threshold value compared with the initial state. Here, the "when each coefficient value of the creep compliance of the tube deformation parameter exceeds the threshold value" means the time when the hydraulic transmission tube 108 is considered to be deteriorated. Such a control device 100 can output a warning to an external device when the hydraulic transmission tube 108 is deteriorated.

[0019] In addition, the control device 100 includes a piston cylinder 102, a flow meter 103, a pressure gauge 104, a joint angle estimation unit 105, a tube deformation correction unit 106, a tube deformation parameter storage unit 107, a pump 110, and a tube deformation parameter calibration unit 120. The control device 100 realizes each function such as the joint angle estimation unit 105, the tube deformation correction unit 106, the tube deformation parameter storage unit 107, and the tube deformation parameter calibration unit 120 by the CPU executing a program stored in the storage means.

[0020] The piston cylinder 102 is a component that adjusts the amount of liquid sent from the control device 100 to the robot 900. The piston cylinder 102 has a cylinder and a piston 302 (Fig. 4) slidably disposed therein. When liquid receiving pressure inside flows into the piston cylinder 102 through the hydraulic transmission tube 108, the piston 302 (Fig. 4) moves within the cylinder. The piston cylinder 102 converts the hydraulic pressure into a mechanical force according to the movement of the piston 302 (Fig. 4) and transmits it to the outside. The joint portion 901 of the robot 900 is mechanically connected to the piston cylinder 102. The robot 900 operates by the combination of the piston cylinder 102 and the joint portion 901. That is, the arm and other links of the robot 900 operate by the combination of the piston cylinder 102 and the joint portion 901.

[0021] The flow meter 103 is a component that measures the flow rate value of the liquid. The flow meter 103 outputs the amount of liquid flowing in the hydraulic transmission tube 108 or a value convertible to the amount of liquid as an analog signal or a digital signal.

[0022] The pressure gauge 104 is a component that measures the pressure value of the liquid. The pressure gauge 104 measures the hydraulic pressure flowing inside the hydraulic transmission tube 108 and outputs it as a digital signal or an analog signal.

[0023] The joint angle estimation unit 105 is a component that estimates the joint angle from the liquid flow rate value. The joint angle estimation unit 105 performs calculations on the liquid volume measured by the flow meter 103 according to the structures of the piston cylinder 102 and the joint part 901. Thereby, the joint angle estimation unit 105 estimates the angle (joint accuracy) of the joint part 901. Here, the explanation is given in terms of the joint angle, but the physical quantity to be estimated is not limited to the angle. For example, the joint angle estimation unit 105 can estimate a physical quantity related to the joint structure, such as the linear reciprocating movement amount, as the physical quantity to be estimated.

[0024] The tube deformation correction unit 106 is a component that corrects various values related to the hydraulic transmission tube 108. The tube deformation correction unit 106 estimates, for example, the strain amount of the hydraulic transmission tube 108a using the pressure value measured by the pressure gauge 104. Then, the tube deformation correction unit 106 corrects the strain amount of the hydraulic transmission tube 108a using the tube deformation parameter storage unit 107.

[0025] The tube deformation parameter storage unit 107 is a component that stores tube deformation parameters. The tube deformation parameter storage unit 107 stores, in time series, the results of comparing each coefficient value of the creep compliance of the tube deformation parameter with the initial state. The tube deformation parameter storage unit 107 includes at least parameters such as creep compliance, tube length, and tube inner diameter.

[0026] The pump 110 is a pressurizing means component that applies pressure to the liquid. The tube deformation parameter calibration unit 120 is a component that calibrates the tube deformation parameters. The tube deformation parameter calibration unit 120 calculates the deformation amount of the hydraulic transmission tube 108 from the difference between the flow rate values before applying pressure to the liquid and after removing the pressure from the liquid, and calibrates the tube deformation parameters according to the deformation amount of the hydraulic transmission tube 108. At that time, the tube deformation parameter calibration unit 120 evaluates the current (actual) deformation state of the hydraulic transmission tube 108 using the pressure value measured by the pressure gauge 104, the flow rate value measured by the flow meter 103, and the tube deformation parameter storage unit 107.

[0027] <Operation of the control device> Hereinafter, with reference to FIG. 2, the operation of the control device 100 will be described. FIG. 2 is a flowchart showing an example of the operation of the control device 100.

[0028] As shown in FIG. 2, when the robot 900 (working device) is driven, the control device 100 drives the pump 110 by the control unit 101 to apply pressure to the liquid (water). Then, the control device 100 transmits the pressure to the piston 902 through the liquid (step S1). Thereby, the control device 100 drives the joint portion 901 of the robot 900. The control device 100 controls the driving of the joint portion 901 of the robot 900 by managing the flow rate (liquid volume) of the fed liquid.

[0029] After step S1, the control device 100 performs tube deformation correction by the tube deformation correction unit 106 (step S2). At this time, the tube deformation correction unit 106 calculates a liquid flow rate fluctuation value corresponding to the liquid pressure value using the tube deformation parameters stored in advance in the tube deformation parameter storage unit 107 and corrects the liquid flow rate value.

[0030] After step S2, the control device 100 estimates the joint angle at the joint portion 901 of the robot 900 from the corrected flow rate value by the joint angle estimation unit 105 (step S3).

[0031] After step S3, the control device 100 calculates the current tube deformation amount from the measured value of the flow rate value before the start of pressure application and the measured value of the flow rate value after the end of pressure application by the tube deformation parameter calibration unit 120, and calibrates the tube deformation parameters (step S4).

[0032] <Deformation example of the hydraulic transmission tube> Hereinafter, with reference to FIG. 3, a deformation example of the hydraulic transmission tube 108 will be described. FIG. 3 is an explanatory diagram of a deformation example of the hydraulic transmission tube 108.

[0033] As shown in FIG. 3, the hydraulic transmission tube 108 undergoes elastic deformation and viscous deformation by receiving the pressure of the pressurized liquid. FIG. 3 shows the shapes of the hydraulic transmission tube 108 in five states from left to right: the non-deformed state, the elastic expansion state, the creep expansion state, the creep extension state, and the residual creep state.

[0034] (1) In the example of the first non-deformed state from the left, no elastic deformation occurs inside the hydraulic transmission tube 108. (2) In the example of the second elastic expansion state from the left, elastic deformation occurs inside the hydraulic transmission tube 108 (the diameter of the hydraulic transmission tube 108 increases while the wall thickness decreases). The elastic deformation recovers immediately when the pressure is relieved. Therefore, the hydraulic transmission tube 108 returns to its original shape (the first shape from the left). (3) In the example of the third creep expansion state from the left, slight viscous deformation occurs inside the hydraulic transmission tube 108. The viscous deformation recovers slowly when the pressure is relieved. Therefore, the hydraulic transmission tube 108 slowly returns to its original shape (the first shape from the left). (4) In the example of the fourth creep extension state from the left, moderate viscous deformation occurs inside the hydraulic transmission tube 108. The viscous deformation in this state recovers even more slowly when the pressure is relieved. Therefore, the hydraulic transmission tube 108 returns to its original shape (the first shape from the left) even more slowly. (5) In the example of the fifth residual creep state from the left, severe viscous deformation occurs inside the hydraulic transmission tube 108. The viscous deformation in this state leaves plastic deformation even when the pressure is relieved. Therefore, the hydraulic transmission tube 108 does not return to its original shape (the first shape from the left).

[0035] <Drive mechanism of the control device> Hereinafter, with reference to FIG. 4, the drive mechanism of the control device 100 will be described. FIG. 4 is a schematic configuration diagram of the drive mechanism of the control device 100.

[0036] As shown in FIG. 4, between the pump 110 and the piston cylinder 102, the control device 100 has two hydraulic drive mechanisms for each joint portion 901 as a drive system for driving the joint portion 901 of the robot 900. Here, the system on the side where the flow meter 103a (flow meter A) is provided is referred to as the "A system", and the system on the side where the flow meter 103b (flow meter B) is provided is referred to as the "B system" (the same applies hereinafter). Note that FIG. 1 shows only the configuration of one side of the system (for example, the A system) out of the A system and the B system. Therefore, the control device 100 has the same configuration as the A system on the B system side between the pump 110 and the piston cylinder 102.

[0037] In the example shown in FIG. 4, the control device 100 has a valve 310c between the pump 110 and the piston cylinder 102. The valve 310c is a component that switches the flow path between the A system side and the B system side.

[0038] The control device 100 branches from the valve 310c and has, as components of the A system, a valve 310a, a flow meter 103a, a potentiometer 320a, and a pressure gauge 104a. The valve 310a is a component that switches the flow path between the flow meter 103a side and the atmosphere side. Further, the control device 100 branches from the valve 310c and has, as components of the B system, a valve 310b, a flow meter 103b, a potentiometer 320b, and a pressure gauge 104b. The valve 310b is a component that switches the flow path between the flow meter 103b side and the atmosphere side.

[0039] The flow meter 103a and the piston cylinder 102 are connected by a hydraulic transmission tube 108a which is a resin tube, and the piston 303a in the flow meter 103a and the piston 302 in the piston cylinder 102 operate in conjunction. Similarly, the flow meter 103b and the piston cylinder 102 are connected by a hydraulic transmission tube 108b which is a resin tube, and the piston 303b in the flow meter 103b and the piston 302 in the piston cylinder 102 operate in conjunction.

[0040] When the robot 900 is driven, the control device 100 opens and closes the valves 310a to 310c in a coordinated manner using the control unit 101. In this way, the control device 100 controls the opening and closing operation and the opening and closing amount of the flow paths of the A system and the B system. As a result, the liquid pressurized by the pump 110 flows into the flow path of the A system or the B system.

[0041] When pressurized liquid is to flow to the A system side, valve 310a is opened to the A system flowmeter 103a side, and valve 310b is opened to the atmosphere side. This causes the pressure in the flow path on the A system side to become atmospheric pressure, and the liquid flows along the dashed arrow. When pressurized liquid is to flow to the B system side, valve 310a is opened to the atmosphere side, and valve 310b is opened to the B system flowmeter 103b side. This causes the pressure in the flow path on the B system side to become atmospheric pressure, and the liquid flows along the solid arrow.

[0042] Potentiometers 320a and 320b linked to the positions of the pistons 303a and 303b are connected to the flow meters 103a and 103b, respectively. The potentiometers 320a and 320b measure the amount of movement of the pistons 303a and 303b of the flow meters 103a and 103b.

[0043] The control device 100 can calculate the flow rate of the liquid by the product of the effective cross-sectional areas of the cylinders of the flow meters 103a and 103b and the movement amounts of the pistons 303a and 303b. The measured values ​​of the flow rate of the liquid measured by the flow meters 103a and 103b relate to the flow rate of the liquid flowing into the piston cylinder 102. The piston 302 of the piston cylinder 102 is mechanically connected to a joint 901, and operates the joint 901 in proportion to the movement amount. Therefore, the control device 100 can estimate the joint angle of the joint 901 of the robot 900 by the joint angle estimation unit 105 from the flow rate values ​​measured by the flow meters 103a and 103b.

[0044] However, the hydraulic transmission tubes 108a and 108b are resin tubes made of flexible resin. Therefore, when the hydraulic transmission tubes 108a and 108b receive the pressure of the pressurized liquid, they undergo elastic deformation and viscous deformation. The elastic deformation of the hydraulic transmission tubes 108a and 108b will immediately return to its original state when the pressure is relieved. However, if the pressurization lasts for a long time and viscous deformation occurs, resulting in residual creep, the plastic deformation due to creep of the hydraulic transmission tubes 108a and 108b will not return to its original state even when the pressure is relieved. Therefore, when plastic deformation due to creep occurs in the hydraulic transmission tubes 108a and 108b, the flow rate of the liquid fluctuates.

[0045] Hereinafter, this point will be described with reference to FIGS. 5A and 5B. Here, the components on the A system side will be described as an example. Here, it is assumed that the control device 100 alternately repeats the hydraulic drive operations on the A system side and the B system side.

[0046] FIG. 5A is an explanatory diagram showing an example of the variation history of the flow rate. As an example, FIG. 5A shows the change in the measured value by the potentiometer 320a on the A system side. The measured value of the potentiometer 320a is linked to the movement of the piston 303a of the flow meter 103a.

[0047] In the example shown in FIG. 5A, the waveform of the measured value of the potentiometer 320a is such that the upper flat area (upper flat area 401) and the lower flat area (lower flat area 402) appear alternately. The upper flat area 401 indicates the timing when the piston 303a of the flow meter 103a is closest to the piston cylinder 102. The lower flat area 402 indicates the timing when the piston 303a of the flow meter 103a is farthest from the piston cylinder 102.

[0048] In the example shown in FIG. 5A, when paying attention to the ○ mark, the upper flat area 401 exists near 0 mm. Also, when paying attention to the × mark, the lower flat area 402 exists near -11 mm. The ○ mark represents the position of the maximum value in the upper flat area 401. Also, the × mark represents the position of the minimum value in the lower flat area 402. Both the ○ mark and the × mark indicate the endpoints of the movable range of the joint angle of the joint portion 901 of the robot 900, and the joint portion 901 cannot move any further even when pressure is applied. The pump pressure is constant (for example, about 3.5 MPa). In the upper flat area 401 and the lower flat area 402, a constant pressure is continuously applied to the piston 902 that drives the joint portion 901 of the robot 900.

[0049] The waveform of the measured value of the potentiometer 320a is related to the movement of the joint portion 901 of the robot 900. Here, it will be described that when the measured value of the potentiometer 320a is the value of the upper flat area 401, the joint portion 901 of the robot 900 opens, and when the measured value is the value of the lower flat area 402, the joint portion 901 of the robot 900 closes. However, the movement of the joint portion 901 of the robot 900 can be changed in the reverse direction. That is, when the measured value of the potentiometer 320a is the value of the upper flat area 401, the joint portion 901 of the robot 900 can be made to close, and when the measured value is the value of the lower flat area 402, the joint portion 901 of the robot 900 can be made to open.

[0050] Figure 5B shows the time variation of the flow rate value drift due to the distortion of the hydraulic transmission tube 108a. In the example shown in Figure 5B, the circles and crosses are obtained by extracting the maximum value within each upper flat area 401 and the minimum value of each lower flat area 402, and plotting them with an enlarged vertical axis scale. In Figure 5B, as shown in the lower plot, each time the hydraulic driving operation is alternately repeated on the A-system side and the B-system side, the value of the flow meter 103a gradually shifts (deviates). As a result, for example, both the maximum value and the minimum value shift by about 0.5 mm. With respect to the straight line of the broken line connecting the first position and the last position, the initial shift amount (deviation amount) first deviates greatly, but the difference gradually becomes smaller.

[0051] <Calibration of Tube Deformation Parameters> Solid polymers such as resin tubes exhibit complex viscoelastic behavior. As typical types of viscoelastic behavior, there are a stress relaxation phenomenon in which stress relaxes with time under a constant strain, and a creep phenomenon in which strain progresses with time under a constant stress. As characteristic values representing these phenomena, a relaxation time distribution function and a retardation time distribution function are used. In the relaxation phenomenon, the stress changes with time for a constant strain. Therefore, assuming that the elastic modulus changes with time, the relaxation elastic modulus Er(t), which is obtained by dividing the stress change by the constant strain using the relaxation time function H(τ), is expressed by the following equation (1).

Equation

[0052] Here, τ represents the time constant, and it is a linear sum of exponential decays with various time constants. Similarly, when the time change of the strain under the condition of constant stress is defined as the creep compliance Jc(t) by dividing the value by the constant stress, the creep compliance Jc(t) is expressed by the following equation (2) using the retardation time distribution function L(τ).

Equation

[0053] Assume that the inner diameter of the hydraulic transmission tube 108 is R1, r1 = (R1 / 2), and the radial strain is γ. Then, the volume change ΔVt of the hydraulic transmission tube 108 from its original shape is expressed by the following formula (3).

Number

[0054] Here, γ includes both elastic deformation and creep deformation. If the effective cross-sectional area of the piston cylinder 102 is Sr, the total stroke amount is Lr, the movable range of the joint portion 901 is θw, and the joint angle displacement is θ, then the liquid volume Vr corresponding to the angular displacement of the joint portion 901 of the robot 900 is expressed by the following formula (4).

Number

[0055] If the effective cross-sectional area of the flowmeter cylinder is Sf and the displacement of the flowmeter potentiometer is x, then the liquid volume V is expressed by the following formula (5).

Number

[0056] Here, since the liquid volume V is the sum of the liquid volume Vr flowing into the piston cylinder 102 in each system and the volume change ΔVt of the hydraulic transmission tube 108 due to stress deformation, the liquid volume V is expressed by the following formula (6).

Number

[0057] Here, when formula (6) is transformed for the volume change ΔVt, the volume change ΔVt is expressed by the following formula (7). [Number]

[0058] From Equation (3) and Equation (7), the strain γ of the hydraulic transmission tube 108 through the joint portion 901 of the robot 900 is represented by the following Equation (8). [Number]

[0059] The creep compliance Jc(t) is defined as the strain divided by the stress S under a constant stress. In reality, it has continuously distributed time constants, but considering that it can be approximated by the sum of exponential functions with a finite number of time constants, the creep compliance Jc(t) is represented by the following Equation (9). [Number]

[0060] Here, when the stress is given as a function σ(t) that changes with time, the strain γ(t) is represented by the following Equation (10) according to Boltzmann's superposition principle. Note that the "Boltzmann superposition principle" means that since the deformation of a material can be divided into small deformation steps, assuming that each step shows an independent response, the deformation amount of the material is the simple superposition of the time and temperature changes of the mechanical properties of the material on the response function of each step. [Number]

[0061] Regarding the evaluation of the deformed state, for example, when the joint portion 901 can no longer operate mechanically, the joint angle is uniquely determined. Therefore, the control device 100 evaluates the deformed state when the amount of liquid present in the piston cylinder 102 is determined. And if the deviation of the tube deformation parameter is large, the tube deformation parameter is calibrated (corrected).

[0062] At that time, for example, the tube deformation parameter calibration unit 120 obtains the upper limit angle parameter and the lower limit angle parameter of the joint angle by operating the piston, and calibrates the tube deformation parameter using the upper limit angle parameter and the lower limit angle parameter. Such a control device 100 can obtain a value whose flow rate changes depending on the posture of the robot 900, or a value whose flow rate is stable.

[0063] The tube deformation parameter calibration unit 120 can calibrate the tube deformation parameter based on the creep compliance. For example, the tube deformation parameter calibration unit 120 obtains the current creep compliance and the creep compliance when a pressure is continuously applied to the liquid for an arbitrary time (the creep compliance after pressure application). Then, the tube deformation parameter calibration unit 120 calculates the change amount by comparing the current creep compliance and the creep compliance after pressure application. The tube deformation parameter calibration unit 120 calibrates the tube deformation parameter according to the change amount of the creep compliance.

[0064] Alternatively, the tube deformation parameter calibration unit 120 may measure the residual creep from the difference in the flow rate values before applying pressure to the liquid and after removing the pressure from the liquid. Then, the residual creep measured from the difference in the flow rate values is compared with the estimated strain amount estimated from the measured pressure value. Thereby, the tube deformation parameter calibration unit 120 calibrates the tube deformation parameter according to the residual creep and the estimated strain amount. Specifically, the tube deformation parameter calibration unit 120 compares the residual creep measured from the difference in the flow rate values before applying pressure to the liquid and after removing the pressure from the liquid with the estimated strain amount estimated from the measured pressure value. Thereby, the tube deformation parameter calibration unit 120 calibrates the tube deformation parameter.

[0065] <Main features of the control device> The control device 100 according to the present embodiment can be configured to have the following features.

[0066] (1) As shown in FIG. 1, the control device 100 according to the present embodiment includes a hydraulic transmission tube 108, a pump 110 (pressure applying means), a pressure gauge 104, and a flow meter 103. The control device 100 also includes a tube deformation correction unit 106, a joint angle estimation unit 105, and a tube deformation parameter calibration unit 120. The hydraulic transmission tube 108 is a component that transmits pressure to the piston 902 that drives the joint portion 901 of the robot 900, which is a working device, via a liquid (water). The pump 110 is a component that applies pressure to the liquid. The pressure gauge 104 is a component that measures the pressure value of the liquid. The flow meter 103 is a component that measures the flow rate value of the liquid. The tube deformation correction unit 106 is a component that calculates the flow rate fluctuation value of the liquid according to the pressure value of the liquid using the previously prepared tube deformation parameter and corrects the flow rate value of the liquid. The joint angle estimation unit 105 is a component that estimates the joint angle from the flow rate value of the liquid. The tube deformation parameter calibration unit 120 is a component that calculates the current tube deformation amount from the measured value of the flow rate value before the start of pressure application and the measured value of the flow rate value after the end of pressure application and calibrates the tube deformation parameter.

[0067] The control device 100 according to such an embodiment can calibrate the tube deformation parameters. Also, since the sensor for measuring the joint angle is susceptible to the influence of radioactivity, the control device 100 can eliminate the need for such a sensor. Further, the control device 100 can correct the deviation caused by the deformation of the hydraulic transmission tube 108, which is a hollow resin tube. Additionally, the control device 100 can improve the operating accuracy of the joint part.

[0068] (2) In the control device 100 according to this embodiment, the tube deformation parameter calibration unit 120 may obtain the upper limit angle parameter and the lower limit angle parameter of the joint angle by operating the piston 902. Then, the tube deformation parameter calibration unit 120 may calibrate the tube deformation parameters using the upper limit angle parameter and the lower limit angle parameter.

[0069] The control device 100 according to such an embodiment can obtain a value whose flow rate changes depending on the posture of the robot 900, or a value at which the flow rate is stable.

[0070] (3) In the control device 100 according to this embodiment, the tube deformation parameter calibration unit 120 may calibrate the tube deformation parameters according to the change amount of the creep compliance. In this configuration, the tube deformation parameter calibration unit 120 calculates the change amount by comparing the current creep compliance with the creep compliance obtained when pressure is continuously applied to the liquid for an arbitrary time. Then, the tube deformation parameter calibration unit 120 calibrates the tube deformation parameters according to the change amount of the creep compliance.

[0071] The control device 100 according to such an embodiment can calibrate the tube deformation parameters according to the change amount of the creep compliance.

[0072] (4) In the control device 100 according to this embodiment, the tube deformation parameter calibration unit 120 may calibrate the tube deformation parameter according to the residual creep and the estimated strain amount. In this configuration, the tube deformation parameter calibration unit 120 compares the residual creep measured from the difference in the flow rate values before applying pressure to the liquid and after removing the pressure from the liquid, with the estimated strain amount estimated from the measured value of the pressure. Then, the tube deformation parameter calibration unit 120 calibrates the tube deformation parameter according to the residual creep and the estimated strain amount.

[0073] The control device 100 according to this embodiment can calibrate the tube deformation parameter according to the residual creep and the estimated strain amount.

[0074] (5) As shown in FIG. 1, the control device 100 according to this embodiment includes a tube deformation parameter storage unit 107 that stores tube deformation parameters, and an output unit 101a that outputs arbitrary information to an external device. The tube deformation parameter storage unit 107 stores, in time series, the results of comparing each coefficient value of the creep compliance of the tube deformation parameter with the initial state. The output unit 101a outputs to the external device the predicted time when each coefficient value of the creep compliance of the tube deformation parameter exceeds the threshold value.

[0075] The control device 100 according to this embodiment can output to the outside the predicted time when the hydraulic transmission tube 108 is considered to be deteriorated.

[0076] (6) As shown in FIG. 1, the control device 100 according to this embodiment includes a warning unit that outputs a warning to an external device. The warning unit outputs a warning when each coefficient value of the creep compliance of the tube deformation parameter exceeds the threshold value compared with the initial state.

[0077] The control device 100 according to this embodiment can output a warning to an external device when the hydraulic transmission tube 108 is deteriorated.

[0078] Further, as shown in FIG. 2, in the present embodiment, a control method for a robot 900 (working device) having a joint portion 901 driven by transmitting pressure to a piston 902 through a liquid can be provided. This control method includes a pressure transmission step, a tube deformation correction step, a joint angle estimation step, and a parameter calibration step. The pressure transmission step is a step of transmitting the pressure applied to the liquid by a pump 110 (pressure applying means) to the piston 902 through a hydraulic transmission tube 108. The tube deformation correction step is a step of calculating a flow rate fluctuation value of the liquid corresponding to the pressure value of the liquid using a prepared tube deformation parameter and correcting the flow rate value of the liquid. The joint angle estimation step is a step of estimating the joint angle from the corrected flow rate value. The parameter calibration step is a step of calculating the current tube deformation amount from the measured value of the flow rate value before the start of pressure application and the measured value of the flow rate value after the end of pressure application, and calibrating the tube deformation parameter.

[0079] Such a control method according to the present embodiment can calibrate the tube deformation parameter. Further, since the sensor for measuring the joint angle is easily affected by radioactivity, the sensor can be made unnecessary. Further, the control method can correct the deviation due to the deformation of the hydraulic transmission tube 108 which is a hollow resin tube. Further, the control method can improve the operation accuracy of the joint portion.

[0080] As described above, according to the control device 100 according to the first embodiment, even when used continuously for a long time, the control accuracy can be maintained. Further, correction can be performed for the creep strain of the resin tube, and the joint angle can be estimated.

[0081] [Second Embodiment] Hereinafter, with reference to FIG. 6, the configuration of a remote work system 1000A including a control device 100A according to the second embodiment will be described. FIG. 6 is a schematic configuration diagram of a remote work system 1000A including a control device 100A according to the second embodiment.

[0082] The remote operation system 1000A according to the second embodiment is different from the remote operation system 1000 (FIG. 1) according to the first embodiment in that the control device 100A has either or both of the thermometer 201 and the heat insulating material 202.

[0083] The thermometer 201 is a component that measures the liquid temperature (water temperature) in the hydraulic transmission tube 108a. In this embodiment, since the liquid is water, the thermometer 201 is composed of a water thermometer that measures the water temperature.

[0084] The tube deformation correction unit 106 calculates, for example, a liquid flow rate fluctuation value corresponding to the liquid pressure value using a previously prepared tube deformation parameter, and corrects the liquid flow rate value. Further, the tube deformation correction unit 106 can perform temperature shift correction of creep compliance using, for example, the liquid temperature measured by the thermometer 201. That is, the tube deformation correction unit 106 can calibrate the creep compliance using a temperature correction coefficient corresponding to the liquid temperature measured by the thermometer. Such a control device 100A can measure the liquid temperature in the hydraulic transmission tube and perform temperature correction. Further, the control device 100A can correct or suppress errors caused by temperature changes.

[0085] The heat insulating material 202 is a component that covers the hydraulic transmission tube 108. The heat insulating material 202 isolates the hydraulic transmission tube 108 from the outside air and suppresses heat transfer between the liquid in the hydraulic transmission tube 108 and the outside air. Thereby, the control device 100A can keep the liquid temperature in the hydraulic transmission tube 108 stable for a relatively long time.

[0086] Further, the control device 100A winds (covers) the heat insulating material 202 around the hydraulic transmission tube 108. Thereby, even if the hydraulic transmission tube 108 passes through a long and temperature-changing location, the control device 100A can reduce the difference between the liquid temperature in the hydraulic transmission tube 108 measured by the thermometer 201 and the actual temperature distribution in the hydraulic transmission tube 108.

[0087] Creep compliance, the material such as nylon used for the hydraulic transmission tube 108, has the characteristic that the time constant changes uniformly due to temperature change. The control device 100A can obtain in advance the temperature change coefficient of creep compliance as a tube deformation parameter and adjust the creep compliance according to the temperature change.

[0088] As shown in FIG. 6, the control device 100A according to the second embodiment has a thermometer 201 that measures the liquid temperature in the hydraulic transmission tube 108. The tube deformation correction unit 106 calibrates the creep compliance using a temperature correction coefficient corresponding to the liquid temperature measured by the thermometer 201. That is, the tube deformation correction unit 106 performs temperature shift correction of the creep compliance using the liquid temperature measured by the thermometer 201.

[0089] The control device 100A according to this embodiment can measure the liquid temperature in the hydraulic transmission tube 108 and perform temperature correction. Further, the control device 100A can correct or suppress errors due to temperature changes.

[0090] Also, as shown in FIG. 6, the control device 100A according to the second embodiment has a heat insulating material that covers the hydraulic transmission tube 108. The heat insulating material isolates the hydraulic transmission tube 108 from the outside air and suppresses heat transfer between the liquid in the hydraulic transmission tube 108 and the outside air.

[0091] The control device 100A according to this embodiment can keep the liquid temperature in the hydraulic transmission tube 108 stable for a relatively long time.

[0092] As described above, according to the control device 100A according to the second embodiment, similar to the control device 100 according to the first embodiment, even when used continuously for a long time, the control accuracy can be maintained. Moreover, different from the control device 100 according to the first embodiment, even when the liquid temperature (water temperature) fluctuates, correction can be performed for the creep strain of the resin tube, and the joint angle can be estimated.

[0093] [Embodiment 3] Hereinafter, with reference to FIG. 7, the configuration of the remote operation system 1000B including the control device 100B according to the third embodiment will be described. FIG. 7 is a schematic configuration diagram of the remote operation system 1000B including the control device 100B according to the third embodiment.

[0094] The remote operation system 1000B according to the third embodiment is different from the remote operation system 1000 (FIG. 1) according to the first embodiment in that the control device 100B includes a deterioration determination unit 501 and a display unit 502. The deterioration determination unit 501 is a component that determines the deterioration of the quality of the hydraulic transmission tube 108.

[0095] The tube deformation parameter storage unit 107 stores in advance deterioration tube deformation parameters for determining the deterioration of the quality of the hydraulic transmission tube 108 (resin tube). The deterioration tube deformation parameters include the initial value of the tube deformation parameters and threshold values (associated threshold values) associated with the quality state of the resin tube acquired in advance (for example, good, inspection required, replacement required, unusable, etc.).

[0096] The deterioration determination unit 501 compares the calibrated tube deformation parameters with the initial values and determines the quality of the hydraulic transmission tube 108 based on the deterioration tube deformation parameters. When the difference between the calibrated tube deformation parameters and the initial values exceeds the threshold value associated with the quality state of the resin tube described above, the deterioration determination unit 501 determines that deterioration has occurred in the hydraulic transmission tube 108. In this case, the deterioration determination unit 501 displays the quality state of the hydraulic transmission tube 108 on the display unit 502.

[0097] As described above, according to the control device 100B according to the third embodiment, similar to the control devices 100 and 100A according to other embodiments, even when used continuously for a long time, the control accuracy can be maintained. Further, correction can be performed for the creep strain of the resin tube, and the joint angle can be estimated. Furthermore, different from the control devices 100 and 100A according to other embodiments, the deterioration state of the quality of the hydraulic transmission tube 108 (resin tube) can be determined and a warning can be displayed.

[0098] FIG. 8 is a block diagram of the computer 980. The control devices 100 and the robot 900 shown in FIG. 1, FIG. 6, etc. include one or more computers 980 shown in FIG. 8. In FIG. 8, the computer 980 includes a CPU 981, a storage unit 982, a communication I / F (interface) 983, an input / output I / F 984, and a media I / F 985. Here, the storage unit 982 includes a RAM 982a, a ROM 982b, and an HDD 982c. The communication I / F 983 is connected to a communication circuit 986. The input / output I / F 984 is connected to an input / output device 987. The input / output device 987 includes a keyboard, a mouse, etc. The media I / F 985 reads and writes data from / to a recording medium 988.

[0099] The ROM 982b stores an IPL (Initial Program Loader) etc. to be executed by the CPU. The HDD 982c stores a control program, various data, etc. The CPU 981 realizes various functions by executing the control program etc. read from the HDD 982c into the RAM 982a.

[0100] The present invention is not limited to the above-described embodiments and includes various modifications. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Also, a part of the configuration of an embodiment can be replaced with another configuration, and another configuration can be added to the configuration of the embodiment. Further, for a part of each configuration, addition, deletion, or replacement with another configuration is possible.

Explanation of Signs

[0101] 100 Control device 101 Control unit 101a Output unit 101b Warning unit 102 Piston cylinder 103, 103a, 103b Flow meter 104, 104a, 104b Pressure gauge 105 Joint angle estimation unit 106 Tube deformation correction unit 107 Tube deformation parameter storage unit 108a, 108b Hydraulic transmission tube (pressure transmission tube) 110 Pump (pressure applying means) 120 Tube deformation parameter calibration unit (parameter calibration unit) 201 Thermometer (water thermometer) 202 Heat insulating material 302 Piston 303a, 303b Piston 310a, 310b, 310c Valve 320a, 320b Potentiometer 401 Upper flat area 402 Lower flat area 501 Deterioration determination unit 502 Display unit 900 Robot (working device) 901 Joint part 902 Piston 1000 Remote operation system

Claims

1. A hydraulic transmission tube that transmits pressure to a piston that drives a joint portion of a working device via a liquid, Pressure applying means for applying pressure to the liquid, A pressure gauge for measuring the pressure value of the liquid, A flow meter for measuring the flow rate value of the liquid, A tube deformation correction unit that calculates a flow rate fluctuation value of the liquid corresponding to the pressure value of the liquid using a previously prepared tube deformation parameter and corrects the flow rate value of the liquid, A joint angle estimation unit that estimates a joint angle from the corrected flow rate value, A parameter calibration unit that calculates a current tube deformation amount from the measured value of the flow rate value before the start of pressure application and the measured value of the flow rate value after the end of pressure application, and calibrates the tube deformation parameter, A control device for a working device, characterized by the above.

2. In the control device for a working device according to Claim 1, The parameter calibration unit acquires an upper limit angle parameter and a lower limit angle parameter of a joint angle by operating the piston, and calibrates the tube deformation parameter using the upper limit angle parameter and the lower limit angle parameter A control device for a working device, characterized by the above.

3. In the control device for a working device according to Claim 1, The parameter calibration unit calibrates the tube deformation parameter by comparing the current creep compliance with the creep compliance obtained when pressure is continuously applied to the liquid for an arbitrary time A control device for a working device, characterized by the above.

4. In the control device for a working device according to Claim 1, The parameter calibration unit calibrates the tube deformation parameter by comparing the residual creep measured from the difference in the flow rate values before and after applying pressure to the liquid and the estimated strain amount estimated from the measured value of the pressure A control device for a working device, characterized by the following.

5. In the control device for a working device according to Claim 1, it has a tube deformation parameter storage unit that stores tube deformation parameters, and an output unit that outputs arbitrary information to an external device, and the tube deformation parameter storage unit stores, in time series, the results of comparing each coefficient value of the creep compliance of the tube deformation parameters with the initial state, and the output unit outputs to the external device the predicted time when each coefficient value of the creep compliance of the tube deformation parameters exceeds a threshold value. A control device for a working device, characterized by the following.

6. In the control device for a working device according to Claim 1, it has a warning unit that outputs a warning to an external device, and when each coefficient value of the creep compliance of the tube deformation parameters exceeds a threshold value compared with the initial state, the warning unit outputs a warning to the external device. A control device for a working device, characterized by the following.

7. In the control device for a working device according to Claim 1, it has a thermometer that measures the liquid temperature of the hydraulic transmission tube, and the tube deformation correction unit calibrates the creep compliance with a temperature correction coefficient according to the liquid temperature measured by the thermometer. A control device for a working device, characterized by the following.

8. In the control device for a working device according to Claim 1, it has a heat insulation material that covers the hydraulic transmission tube, and the heat insulation material isolates the hydraulic transmission tube from the outside air and suppresses heat transfer between the liquid in the hydraulic transmission tube and the outside air. A control device for a working device, characterized by the following.

9. In the control device of the working device according to claim 1, having a deterioration determination unit that determines deterioration of the quality of the hydraulic transmission tube A control device for a working device, characterized by the above.

10. A control method for a working device having a joint portion that is driven by transmitting pressure to a piston through a liquid, comprising: a pressure transmission step of transmitting the pressure applied to the liquid by a pressure application means to the piston through a hydraulic transmission tube; a tube deformation correction step of calculating a flow rate fluctuation value of the liquid corresponding to the pressure value of the liquid using a previously prepared tube deformation parameter and correcting the flow rate value of the liquid; a joint angle estimation step of estimating a joint angle from the corrected flow rate value; a parameter calibration step of calculating a current tube deformation amount from a measured value of the flow rate value before the start of pressure application and a measured value of the flow rate value after the end of pressure application and calibrating the tube deformation parameter, A control method for a working device, characterized by the above.

Images