Hydraulic drive robot fault diagnosis system

Abstract

To provide a hydraulic drive robot fault diagnosis system which can perform fault diagnosis without interrupting work even when a sensor or the like composed of electronic components is not mounted on a hydraulic drive robot side in high radiation dose area.SOLUTION: A hydraulic drive robot fault diagnosis system includes an actuator which is operated by hydraulic pressure. The hydraulic drive robot fault diagnosis system further includes: at least one radiation resistance measuring device for measuring an operation of the hydraulic drive robot; a simulator which has a data storage region for recording a control signal and an operation of the hydraulic drive robot and calculates a behavior of the hydraulic drive robot by inputting the control signal; and an analyzing section which compares the behavior of the hydraulic drive robot in an actual machine with a result calculated by the simulator and performs fault diagnosis.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a fault diagnosis system for a hydraulic drive robot, and more particularly to a fault diagnosis system for a hydraulic drive robot that is hydraulically driven and used, for example, in a high-radiation environment where it is difficult for humans to enter.

Background Art

[0002] Generally, in a high-radiation environment where it is difficult for humans to enter, in order to carry out work, an operator in a remote area (low-radiation area) needs to operate a robot in a high-radiation area. In a high-radiation environment, there is a concern that many electronic components may fail in a short period of time. Instead of a robot that controls joint movements with an electric motor or the like, a hydraulic drive robot driven by hydraulic pressure or oil pressure described in Patent Document 1 is suitable.

[0003] A hydraulic drive device having a tank and a pump is installed in a low-radiation area and is connected to a hydraulic drive robot in a high-radiation area by a flexible tube. The hydraulic drive robot has a plurality of hydraulic actuators and operates with hydraulic pressure from the hydraulic drive device. When the hydraulic drive robot fails within a high-radiation area, it is difficult to access the hydraulic drive robot directly for repair. It is necessary to pull back the hydraulic drive robot to a low-radiation area and re-introduce a new hydraulic drive robot to perform the work. When it becomes difficult for the hydraulic drive robot to return to the low-radiation area by itself due to a failure, a separate robot for recovering the hydraulic drive robot is required, and a large delay will occur in the work that was originally intended to be performed for this recovery work. In order to remotely operate the hydraulic drive robot, it is necessary to grasp the behavior of the operating hydraulic drive robot.

[0004] Sensors and the like that use electronic components have a concern of failing in a short period of time. Therefore, it is assumed that measuring instruments such as cameras and lasers with radiation resistance are used to grasp the behavior. There are various methods for detecting robot failures. In Patent Document 2, the behavior grasped from the captured image is compared with the behavior calculated from the rotation angle of the motor that drives the robot arm, and the detection of failures is realized without performing advanced calculations. A failure diagnosis system for a hydraulic drive robot suitable for long-term remote work in a high-radiation environment where it is difficult for humans to enter is desired.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, the robot failure diagnosis system of the conventional technology described above has the following problems. When used in a high-radiation environment, there is a concern that electric motors and sensors for grasping their rotation angles may fail in a short period of time, which may affect the success or failure of the diagnosis.

[0007] Therefore, an object of the present invention is to provide a failure diagnosis system for a hydraulic drive robot that can perform failure diagnosis even when no sensor made of electronic components is mounted on the hydraulic drive robot side.

Means for Solving the Problems

[0008] A hydraulic drive robot fault diagnosis system comprising an actuator that operates hydraulically, at least one radiation-resistant measuring instrument that measures the operation of the hydraulic robot, a data storage area that records the control signal and operation of the hydraulic robot, a simulator that calculates the behavior of the hydraulic drive robot using the control signal as an input, and an analysis unit that compares the behavior of the actual hydraulic drive robot obtained from the information from the radiation-resistant measuring instrument with the result calculated by the simulator and performs fault diagnosis.

Advantages of the Invention

[0009] According to the hydraulic drive robot fault diagnosis system of the present invention, fault diagnosis can be performed even when no sensor made of electronic components is installed in the hydraulic drive robot.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Modes for Carrying Out the Invention

[0011] Hereinafter, an embodiment of a hydraulic drive robot fault diagnosis system according to the present invention will be described with reference to the drawings. In a high-radiation environment where it is difficult for humans to enter, such as a nuclear power plant, an operator in a remote area (low-radiation area 9a) operates a robot in a high-radiation area 9b in order to perform work.

[0012] Figure 1 is a first schematic configuration diagram schematically showing a hydraulic drive robot fault diagnosis system of the present invention. In the case where an operator 7 is involved, the hydraulic drive robot 1 operates with a plurality of hydraulic actuators and hydraulic motors and is configured to perform work in a high-radiation area 9b.

[0013] The hydraulic drive unit 2 includes a pump, and the pump is rotated by an engine or a motor. The high hydraulic pressure is sent to the hydraulic actuators of the hydraulic drive robot 1 through a hydraulic tube 3, and thus the hydraulic drive robot 1 operates. The hydraulic drive robot 1 moves from a low-radiation area 9a to a high-radiation area 9b and performs work there. For this reason, at least a part of the hydraulic tube 3 needs to be flexible.

[0014] The hydraulic drive robot 1 operates by the expansion and contraction of the hydraulic actuators and the rotation of the hydraulic motors. However, there is a control valve between the hydraulic drive unit 2 and the hydraulic drive robot 1. By switching these, it is determined which hydraulic actuators and hydraulic motors are to be operated, and the operating parts of the hydraulic drive robot 1 are switched.

[0015] The control valve is arranged in the hydraulic drive unit 2 or between the hydraulic tubes 3. When the operator 7 inputs the operation of the hydraulic drive robot 1 to the input device 6, the control operation of the control valve is performed by the operation and data storage device 4. Also, a display device 5 is installed.

[0016] The operation of the hydraulic drive robot 1 is monitored by at least one radiation-resistant measuring instrument 8 such as a camera or a laser, even when sensors and the like composed of electronic components are mounted, because there is a concern about their failure in a short period. Operations are carried out by the operation and data storage device 4 from data such as images obtained by the radiation-resistant measuring instrument 8, and it is possible to grasp the position, speed, and acceleration of the hydraulic drive robot 1 and its respective parts.

[0017] Figure 2 is a second schematic configuration diagram schematically showing the hydraulic drive robot fault diagnosis system of the present invention. This is the case of full automation where the operator 7 is not required. When the operation of the hydraulic drive robot 1 is fully automated, the input device 6 is not required, and data such as images obtained by the radiation-resistant measuring instrument 8 are sent to the operation and data storage device 4, grasping the position, speed, and acceleration of the hydraulic drive robot 1 and its respective parts, and simultaneously grasping the working environment and the object held by the robot. Then, the operation and data storage device 4 calculates the next operation and issues a command to the control valve to operate the hydraulic drive robot 1.

Example

[0018] Figure 3 is a flow showing the diagnosis method of Example 1 of the hydraulic drive robot fault diagnosis system of the present invention. In the actual machine, when a control command enters the hydraulic drive control unit 10 composed of the hydraulic drive unit 2 and the control valve, the hydraulic pressure is transmitted to the hydraulic drive robot 1 and it operates. The operations of the respective parts of the hydraulic drive robot 1 are measured by the radiation-resistant measuring instrument 8 and sent to the operation and data storage device 4. The operation and data storage device 4 calculates the position, speed, and acceleration of each part, and these state quantities are stored in the operation and data storage device 4.

[0019] The hydraulic drive robot fault diagnosis system of this embodiment has a simulator 13 composed of a hydraulic drive control circuit unit 11 and a robot mechanism model unit 12. The same control commands as those of the actual machine are first sent to the hydraulic drive control circuit unit 11 of the simulator 13. The hydraulic drive control circuit unit 11 is configured as a hydraulic circuit considering the discharge flow rate of the actual machine pump, the tank for storing the liquid, the opening area of the throttle such as the control valve and the hydraulic tube 3, the connector, the operation of the control valve, and the internal volume of the hydraulic actuator and the hydraulic motor. The hydraulic pressure of each part is calculated by the arithmetic and data storage device 4, and the thrust of the hydraulic actuator and the rotational torque of the hydraulic motor are calculated. In addition, in the flexible part of the hydraulic tube 3, the volume change due to the expansion by the hydraulic pressure is also considered.

[0020] Next, the robot mechanism model unit 12 models the mechanism of the hydraulic drive robot 1. By modeling the parts as rigid bodies or elastic bodies, connecting the parts with joints so that they have the same degrees of freedom as the actual machine, and solving their equations of motion as a multi-inertia model, the same behavior as the actual machine can be calculated.

[0021] The robot mechanism model unit 12 considers the friction of each part. Regarding the consideration of friction, there are a method with a small calculation load for defining the frictional force with respect to the relative speed between the sliding parts, and a method that is closer to the actual phenomenon but has a relatively heavy calculation load, which calculates the contact force between the parts, sets the static friction coefficient and the dynamic friction coefficient with respect to the relative speed, and calculates the frictional force from the contact force. When it is necessary to calculate in a short time and calculate in the same time as the operation of the actual machine, it is desirable to adopt a method with a small calculation load. When emphasizing accuracy rather than calculation speed, it is desirable to adopt a method with a relatively heavy calculation load for setting the friction coefficient.

[0022] The thrust of the hydraulic actuator and the rotational torque of the hydraulic motor calculated by the device 4 for calculation and data storage are calculated as external forces in the equations of motion of the robot mechanism model unit 12. With these configurations, the positions, velocities, and accelerations of each part of the hydraulic drive robot 1 are calculated and calculated in the same way as the actual machine. The frictional forces of the joints, hydraulic actuators, and hydraulic motors of the hydraulic drive robot 1 are set in advance for the frictional forces and friction coefficients of the simulator 13 so that the behaviors of the actual machine and the simulator 13 match within a determined error range.

[0023] If the hydraulic drive robot 1 is used for a long time, the frictional forces of the joints, hydraulic actuators, and hydraulic motors may increase, and the movement may become slow. In such a case, if use continues for an even longer period, there is a concern that the joints, hydraulic actuators, and hydraulic motors of the hydraulic drive robot 1 may stop operating and it may not be able to return from the high radiation area 9b by itself.

[0024] The actual state quantities of the positions, velocities, and accelerations of each part of the hydraulic drive robot 1 are compared with the model state quantities of the positions, velocities, and accelerations of each part calculated by the simulator 13. A threshold value is set in advance. If a deviation greater than or equal to the set threshold value occurs, it is determined that there is a failure in this part. As a result, it becomes possible to move the hydraulic drive robot 1 to the low radiation area 9a before the hydraulic drive robot 1 becomes unable to return from the high radiation area 9b to the low radiation area 9a by itself. Thus, according to the first embodiment, even when no sensor made of electronic components is installed in the hydraulic drive robot, failure diagnosis is possible.

[0025] Conventionally, when the operator 7 is operating the hydraulic drive robot 1, there is a possibility of noticing a failure, but since it is judged based on an individual's skill, it is difficult to judge a failure objectively and with a certain standard. That is, regardless of an individual's skill, an appropriate objective judgment becomes possible. Also, in the case of full automation, since the operator 7 is not always in a monitoring situation, it is difficult to notice, and the hydraulic drive robot failure diagnosis system of the present invention is more useful.

[0026] While grasping the actual state quantities of the hydraulic drive robot 1, simultaneously calculate the model state quantities by the simulator 13, continuously compare the state quantities, and there is also a method of constantly performing fault diagnosis during the operation of the hydraulic drive robot 1. However, it is conceivable that the calculation time of the simulator 13 is slower than the actual operation. In this case, the grasped actual state quantities can be stored in the operation and data storage device 4, and fault diagnosis may be performed when the model state quantities are calculated from the simulator 13. Also, performing fault diagnosis only at specific timings is also effective.

[0027] In the working state, when the hydraulic drive robot 1 is grasping an object and when it is not grasping an object, the actual state quantities of the positions, speeds, and accelerations of each part of the hydraulic drive robot 1 may change significantly due to the influence of inertia and the like. Therefore, it is desirable to perform fault diagnosis when the hydraulic drive robot 1 is not grasping an object.

[0028] Also, by grasping the shape and size of the object from data such as images from the radiation resistance measuring device 8, estimating the weight of the grasped object, and using this estimated weight in the simulator 13, it is also possible to constantly perform fault diagnosis. That is, fault diagnosis becomes possible including when the hydraulic drive robot 1 is grasping an object.

Example

[0029] FIG. 4 is a flow showing the diagnosis method of Example 2 of the hydraulic drive robot fault diagnosis system of the present invention. Descriptions of portions overlapping with Example 1 are omitted. In this example, the simulator 13 estimates the frictional force and the friction coefficient from the actual state quantities of the positions, speeds, and accelerations of each part of the hydraulic drive robot 1, and performs fault diagnosis based on the changes in the initial frictional force and the friction coefficient. In this way, by estimating the frictional force and the friction coefficient by the simulator 13 from the actual state quantities of the positions, speeds, and accelerations of each part of the hydraulic drive robot 1 and grasping the changes in the initial frictional force and the friction coefficient, it is possible to grasp the deterioration of the actual machine and the like. By comparing the initial frictional force and the friction coefficient with those of the actual machine during or after operation and setting a threshold value, fault judgment can be made.

Example

[0030] Fault diagnosis by image comparison will be described. FIG. 5 is a schematic diagram of a fault diagnosis system for an actual hydraulic drive robot in Example 3, and FIG. 6 is a schematic diagram of a fault diagnosis system for a simulator of the hydraulic drive robot in Example 3. In FIG. 5, the hydraulic drive robot 1 is photographed by an actual radiation-resistant measuring instrument 8 from a predetermined position and direction.

[0031] In FIG. 6, an example in the simulator 13 will be described. For the robot model 14 displayed on the simulator 13, a viewpoint 15 assuming the actual radiation-resistant measuring instrument 8 is set. This viewpoint 15 is set at the same position and direction as the radiation-resistant measuring instrument 8 of the actual machine. In such a case, the image of the hydraulic drive robot 1 obtained from the radiation-resistant measuring instrument 8 of the actual machine and the robot model 14 drawn by the simulator 13 have the same positional relationship. It is also possible to diagnose a fault from the difference in the comparison of each image.

[0032] With these structures, it is possible to provide a hydraulic drive robot fault diagnosis system that can diagnose a fault without interrupting work even when no sensor made of electronic components is mounted on the hydraulic drive robot side.

Explanation of Signs

[0033] 1... Hydraulic drive robot 2... Hydraulic drive unit 3... Hydraulic tube 4... Device for calculation and data storage 5... Display device 6... Input device 7... Operator 8... Radiation-resistant measuring instrument 9a... Low radiation area 9b... High radiation area 10... Hydraulic drive control unit 11... Hydraulic drive control circuit unit 12... Robot mechanism model unit 13... Simulator 14... Robot model 15... Viewpoint

Claims

1. A hydraulic drive robot fault diagnosis system comprising an actuator operated by hydraulic pressure, at least one radiation-resistant measuring instrument for measuring the operation of the hydraulic drive robot, a data storage area for recording the control signal and operation of the hydraulic drive robot, a simulator for calculating the behavior of the hydraulic drive robot using the control signal as an input, and an analysis unit for comparing the behavior of the actual hydraulic drive robot obtained from the information from the radiation-resistant measuring instrument with the result calculated by the simulator and performing fault diagnosis. A hydraulic drive robot fault diagnosis system.

2. In the hydraulic drive robot fault diagnosis system according to Claim 1, the simulator includes a hydraulic drive control unit constructed as a hydraulic circuit considering the discharge flow rate of the pump, the tank for storing the liquid, the opening area of the throttle such as the control valve and the hydraulic tube and the connector, the operation of the control valve, the internal volume of the hydraulic actuator and the hydraulic motor, and the expansion of the hydraulic tube, and a robot mechanism model unit that models the mechanism of the hydraulic drive robot with parts as rigid bodies or elastic bodies, connects the parts with joints so as to have the same degrees of freedom as the actual machine, and solves their equations of motion as a multi-inertia model. A hydraulic drive robot fault diagnosis system characterized by this.

3. In the hydraulic drive robot fault diagnosis system according to Claim 2, the sliding part of the robot mechanism model unit of the simulator is characterized by considering the frictional force according to the relative speed between parts. A hydraulic drive robot fault diagnosis system.

4. In the hydraulic drive robot fault diagnosis system according to Claim 2, the sliding part of the robot mechanism model unit of the simulator calculates the contact force between parts, and considers the friction coefficient set according to the relative speed between parts A hydraulic drive robot fault diagnosis system characterized by this.

5. In the hydraulic drive robot fault diagnosis system according to Claim 1, in the fault diagnosis, a friction coefficient set according to the relative speed between parts is set, the state quantities such as the speed, acceleration, and position of each part of the hydraulic drive robot are compared with the calculation result of the simulator, and fault diagnosis is performed considering the friction coefficient. A hydraulic drive robot fault diagnosis system characterized by this.

6. In the hydraulic drive robot fault diagnosis system according to Claim 1, A hydraulic drive robot fault diagnosis system characterized by judging from the calculation result from the simulator of the frictional force or the friction coefficient of the sliding part of the hydraulic drive robot.

7. In the hydraulic drive robot fault diagnosis system according to claim 1, the simulator has a function of visualizing the behavior of the hydraulic drive robot, A hydraulic drive robot fault diagnosis system characterized in that the visualization result of the behavior of the hydraulic drive robot from the simulator according to the actual installation position of the radiation resistance measuring device is compared with the image acquired by the radiation resistance measuring device.

8. In the hydraulic drive robot fault diagnosis system according to claim 1, A hydraulic drive robot fault diagnosis system characterized by estimating the weight of an object held by the hydraulic drive robot from an image obtained from the radiation resistance measuring device.

Images