Electric actuator, control device and control program

Abstract

To achieve detection of an abnormality based on a conversion operation of a power unit.SOLUTION: An electric actuator includes: a power part for generating power and a state detection part for detecting a state of the power part, based on detection values before and after conversion of a signal or movement converted by the power part.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an electric actuator, a control device, and a control program. [Background technology]

[0002] In flying objects such as airplanes and helicopters, electric actuators that drive various devices by displacing so as to expand and contract along a linear direction are often used. In such electric actuators, failures such as seizure or adhesion can occur in the drive mechanisms such as gears or screws.

[0003] Patent Document 1 discloses a technology for detecting which of multiple gear mechanisms equipped in an electric actuator has a malfunction due to sticking or the like, based on the results of comparing a current detection value of a first motor connected to a first gear mechanism with a current detection value of a second motor connected to a second gear mechanism. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2016-146738 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, the technology disclosed in Patent Document 1 uses the current detection values ​​of the two motors to detect which of the multiple gear mechanisms is at fault. Therefore, it is only possible to detect faults in the gear mechanism directly connected to the motor, and is not possible to detect faults in other mechanisms (output shafts, etc.). In addition, since fault detection relies solely on the motor current sensor, if the current sensor fails, it is not possible to detect an abnormal state. Therefore, an object of the present invention is to provide an electric actuator, a control device, and a control program that are capable of detecting an abnormality based on the conversion operation of a power unit. [Means for solving the problem]

[0006] In order to solve the above problems, an electric actuator according to one aspect of the present invention includes a power unit that generates power, and a state detection unit that detects the state of the power unit based on detection values ​​before and after conversion of a signal or movement converted by the power unit.

[0007] This makes it possible to detect abnormalities based on the detection values ​​before and after conversion of the internal state of the electric actuator alone, and allows abnormality detection to be performed by the electric actuator alone while easing restrictions on the locations or states in which abnormalities in the power unit can be detected. This makes it possible to improve the diversity and flexibility of data processing or data acquisition required for detecting abnormalities in the power unit, and to achieve high accuracy and efficiency in abnormality analysis of the electric actuator.

[0008] Furthermore, the electric actuator according to one aspect of the present invention further includes an output section that outputs a detection result of the state of the power section.

[0009] This makes it possible to notify the user of an abnormal state of the power unit, enabling the user to confirm the abnormal state of the power unit.

[0010] In addition, in an electric actuator according to one aspect of the present invention, the power unit includes a motor, a linear motion device that performs linear motion based on the rotational motion of the motor, and an output shaft that outputs axial force based on the linear motion of the linear motion device.

[0011] This makes it possible to obtain a large axial output from a relatively small input torque, making it possible to use the electric actuator as a vibration damping device for a vehicle while suppressing the increase in size, and also to detect abnormalities in the linear motion device and output shaft beyond the motor. Therefore, even in cases where a high level of safety is required, the electric actuator can be applied without increasing the difficulty of handling and installing the electric actuator.

[0012] Furthermore, an electric actuator according to one aspect of the present invention further includes a motor control unit that controls the motor based on a detected value of a drive current of the motor and a detected value of a rotational position of the motor.

[0013] This makes it possible to detect an abnormal state of the motor while controlling the motor based on the drive current and rotation position of the motor. In this case, the sensor that detects the drive current and rotation position of the motor can be used not only for controlling the motor but also for detecting an abnormality in the motor, and since there is no need to provide a separate sensor dedicated to detecting an abnormality in the motor, it is possible to achieve high accuracy and efficiency in abnormality analysis while suppressing the increase in size and cost of the electric actuator.

[0014] In addition, in the electric actuator according to one aspect of the present invention, the motor control unit controls the motor based on the detection result of the abnormal state of the power unit.

[0015] This makes it possible to stop or slow down the motor if an abnormal condition in the power unit is detected, thereby improving safety while preventing the mechanical configuration of the electric actuator from becoming too complicated.

[0016] Furthermore, according to an electric actuator according to one embodiment of the present invention, the state detection unit detects an abnormal state of the power unit based on at least two of the detection values ​​of the state of the motor, the detection value of the state of the linear motion device, and the detection value of the state of the output shaft.

[0017] This makes it possible to detect abnormalities not only in the motor, but also in the linear motion device and output shaft beyond the motor, thereby making it possible to improve the accuracy and efficiency of abnormality analysis of electric actuators.

[0018] Furthermore, in the electric actuator according to one aspect of the present invention, the state detection unit detects the state of the power unit based on a comparison result between the estimated value of the axial force estimated from the detected value of the drive current of the motor and the detected value of the axial force output from the output shaft.

[0019] This makes it possible to control the axial force output from the output shaft based on the drive current of the motor, while detecting the drive current of the motor and the axial force output from the output shaft to detect an abnormal state in the power transmission system from the motor to the output shaft. This makes it possible to improve the safety and maintainability of the electric actuator during use while preventing the mechanical configuration of the electric actuator from becoming too complicated.

[0020] Moreover, the electric actuator according to one aspect of the present invention further includes a current sensor that detects a drive current of the motor, and an axial force sensor that detects the axial force.

[0021] This makes it possible to detect the motor's drive current and the axial force output from the output shaft, and based on the motor's drive current and the axial force output from the output shaft, it is possible to detect an abnormal condition in the power transmission system from the motor to the output shaft.

[0022] Furthermore, in an electric actuator according to one aspect of the present invention, the state detection unit detects the state of the power unit based on a comparison result between an estimated value of the position of the output shaft, which is estimated from a detected value of the drive current of the motor, and a detected value of the position of the output shaft.

[0023] This makes it possible to control the position of the output shaft based on the drive current of the motor, while detecting the drive current of the motor and the position of the output shaft makes it possible to detect an abnormal state in the power transmission system from the motor to the output shaft.As a result, it is possible to improve the safety and maintainability of the electric actuator during use while preventing the mechanical configuration of the electric actuator from becoming too complicated.

[0024] In addition, the electric actuator according to one aspect of the present invention further includes a current sensor that detects a drive current of the motor, and a position sensor that detects a position of the output shaft.

[0025] This makes it possible to detect the motor's drive current and the position of the output shaft, and based on the motor's drive current and the position of the output shaft, it is possible to detect an abnormal condition in the power transmission system from the motor to the output shaft.

[0026] In addition, in the electric actuator according to one aspect of the present invention, the position sensor is a remote sensor.

[0027] This eliminates the need to directly install the position sensor on the output shaft, and makes it possible to detect the position of the output shaft even in cases where the space for directly installing the position sensor on the output shaft cannot be secured.

[0028] Furthermore, in an electric actuator according to one aspect of the present invention, the state detection unit detects the state of the power unit based on a comparison result between an estimated value of the position of the output shaft, which is estimated from a detected value of the rotational position of the motor, and the detected value of the position of the output shaft.

[0029] This makes it possible to control the position of the output shaft based on the rotational motion of the motor, while detecting the rotational position of the motor and the position of the output shaft, thereby making it possible to detect abnormal conditions in the power transmission system from the motor to the output shaft.As a result, it is possible to improve the safety and maintainability of the electric actuator during use while preventing the mechanical configuration of the electric actuator from becoming too complicated.

[0030] In addition, the electric actuator according to one aspect of the present invention further includes a rotational position sensor that detects the rotational position of the motor, and a position sensor that detects the position of the output shaft.

[0031] This makes it possible to detect the rotational position of the motor and the position of the output shaft, and based on the rotational position of the motor and the position of the output shaft, it is possible to detect an abnormal condition in the power transmission system from the motor to the output shaft.

[0032] Furthermore, in an electric actuator according to one aspect of the present invention, the state detection unit detects the state of the power unit based on a comparison result between an estimated value of the input torque of the linear motion device, which is estimated from a detected value of the drive current of the motor, and a detected value of the input torque of the linear motion device.

[0033] This makes it possible to control the axial force output from the output shaft based on the drive current of the motor, while detecting the drive current of the motor and the input torque of the linear motion device to detect an abnormal state in the power transmission system from the motor to the linear motion device. This makes it possible to improve the safety and maintainability of the electric actuator during use while preventing the mechanical configuration of the electric actuator from becoming too complicated.

[0034] Moreover, the electric actuator according to one aspect of the present invention further includes a current sensor that detects a drive current of the motor, and a torque sensor that detects an input torque of the linear motion device.

[0035] This makes it possible to detect the motor drive current and the input torque of the linear motion device, and based on the motor drive current and the input torque of the linear motion device, it is possible to detect an abnormal state in the power transmission system from the motor to the linear motion device.

[0036] In addition, an electric actuator according to one aspect of the present invention further includes a reducer that generates an input to the linear motion device based on an output of the motor, and the torque sensor is installed in the reducer.

[0037] This makes it possible to adjust the input torque of the linear motion device, and also makes it possible to detect the input torque of the linear motion device while reducing the difficulty in handling and installing the torque sensor.

[0038] Moreover, the electric actuator according to one aspect of the present invention is applied to a vibration damping device.

[0039] As a result, by outputting an axial force from the output shaft that is in the opposite phase to the vibration from the vibration source, it is possible to cancel out the vibration from the vibration source, and it is also possible to improve the accuracy and efficiency of abnormality analysis of the electric actuator.

[0040] In addition, an electric actuator according to one aspect of the present invention includes a drive source that generates power, a first sensor that detects an output state of the drive source, a second sensor that detects a state of an output member that is driven via an intermediate member in accordance with the output state of the drive source, an estimation unit that calculates an estimated value that is an estimated state of the output member based on a detection value of the first sensor, and a state detection unit that detects the state of a path from the drive source to the output member based on a comparison result between the estimated value and the detection value of the second sensor.

[0041] This makes it possible to check whether the state of the output member corresponds to the state expected from the output state of the drive source while driving the output member from the drive source via the intermediate member, and detects abnormal states in the path from the drive source to the output member. This makes it possible to prevent the mechanical configuration of the electric actuator from becoming complicated, and to improve the safety and maintainability of the electric actuator when in use, without interfering with the normal operation of the electric actuator.

[0042] In addition, according to one embodiment of the control device of the present invention, it is equipped with a control unit that controls a power unit that generates power, and a state detection unit that detects the state of the power unit based on the detection values ​​before and after conversion of the signal or movement converted by the power unit.

[0043] This makes it possible to detect abnormalities based on the detection values ​​before and after conversion of the internal state of the electric actuator alone, making it possible to perform abnormality detection in the electric actuator alone while improving the accuracy and efficiency of abnormality analysis of the electric actuator.

[0044] In addition, according to a control program of one embodiment of the present invention, a computer is caused to execute the steps of acquiring a detection value before conversion of the signal or movement converted by the power unit, acquiring a detection value after conversion of the signal or movement converted by the power unit, and detecting the state of the power unit based on the detection value before conversion of the signal or movement converted by the power unit.

[0045] This makes it possible to detect abnormalities based on the detection values ​​before and after conversion of the internal state of the electric actuator alone, making it possible to perform abnormality detection in the electric actuator alone while improving the accuracy and efficiency of abnormality analysis of the electric actuator. Effect of the Invention

[0046] According to one aspect of the present invention, an abnormality based on the conversion operation of the power unit can be detected. [Brief description of the drawings]

[0047] [Figure 1] FIG. 1 is a block diagram showing the configuration of an electric actuator according to a first embodiment. [Diagram 2] FIG. 2 is a block diagram showing an example of a hardware configuration of a data processing unit used in the control device of FIG. [Diagram 3] FIG. 3 is a flowchart showing an example of an abnormality detection process for the electric actuator of FIG. [Figure 4] FIG. 4 is a flowchart showing another example of the abnormality detection process of the electric actuator of FIG. [Diagram 5] FIG. 5 is a flowchart showing still another example of the abnormality detection process for the electric actuator of FIG. [Figure 6] FIG. 6 is a block diagram showing the configuration of an electric actuator according to the second embodiment. [Figure 7] FIG. 7 is a block diagram showing the configuration of an electric actuator according to the third embodiment. [Figure 8] FIG. 8 is a flowchart showing an example of an abnormality detection process for the electric actuator of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0048] Hereinafter, the embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the present invention, and not all of the combinations of features described in the embodiments are necessarily essential to the configuration of the present invention. The configuration of the embodiments may be appropriately modified or changed depending on the specifications of the device to which the present invention is applied and various conditions (conditions of use, environment of use, etc.). The technical scope of the present invention is determined by the claims, and is not limited by the individual embodiments below. Also, the drawings used in the following description may differ in scale and shape from the actual structure in order to make each configuration easier to understand.

[0049] FIG. 1 is a block diagram showing the configuration of an electric actuator according to a first embodiment. 1, the electric actuator includes a control device 1 and a power unit 9 A. The control device 1 is connected to a higher-level device 8.

[0050] The power unit 9A generates power based on a coordinated operation. For example, the power unit 9A can generate power based on a coordinated operation between a drive source that generates power and an output member that is driven via an intermediate member according to the output state of the drive source. The intermediate member can convert the output of the drive source or transmit it to the output member. In the example of FIG. 1, the drive source is the motor 2, the intermediate members are the reducers 3A to 3C and the linear motion device 5, and the output member is the output shaft 6. At this time, the power unit 9A can convert a signal or motion. The signal here is, for example, an electric signal. The motion here is, for example, a rotational motion, a linear motion, a reciprocating motion, or a rocking motion.

[0051] The control device 1 controls the power unit 9A and monitors the operation of the power unit 9A. At this time, the control device 1 calculates an estimated value, which is an estimated state of the output member, based on the detected value of the output state of the drive source, and can detect the state of the path from the drive source to the output member based on the result of comparing the estimated value with the detected value of the state of the output member.

[0052] The higher-level device 8 can monitor the operation of the electric actuator and manage the operation of the electric actuator. The higher-level device 8 is, for example, a host or a terminal capable of communicating with the control device 1.

[0053] The control device 1 includes a motor control unit 11, a motor angle calculation unit 12, a current sensor 13, an abnormality detection unit 14, and an abnormality output unit 15. The abnormality detection unit 14 includes an estimation unit 14A that calculates an estimated value, which is an estimated state of the output member, based on a detected value of the output state of the drive source. This estimation unit 14A may be realized by a calculation device such as a processor.

[0054] The power unit 9A includes a motor 2, reducers 3A to 3C, a bearing 4, a linear motion device 5, a connecting portion 5C, an output shaft 6, and a sensor 7A. The motor 2 includes a rotational position sensor 2A. The rotational position sensor 2A can be used as a first sensor for detecting the output state of the drive source. The linear motion device 5 includes a screw shaft 5A and a nut 5B. The motor 2 is connected to the linear motion device 5 via the reducers 3A to 3C. The output shaft 6 is connected to the linear motion device 5 via the connecting portion 5C.

[0055] The motor control unit 11 controls the motor 2 based on the detected value of the drive current of the motor 2 and the detected value of the rotational position of the motor 2. The motor control unit 11 can include an inverter that generates the drive current of the motor 2. The motor control unit 11 can also control the motor 2 based on the detection result of an abnormal state of the power unit 9A. The motor angle calculation unit 12 calculates the motor angle based on the detected value of the rotational position of the motor 2. The current sensor 13 detects the drive current that drives the motor 2.

[0056] The abnormality detection unit 14 detects an abnormal state of the power unit 9A based on the detection value before conversion of the signal or motion converted by the power unit 9A and the detection value after conversion. At this time, the combination of the detection value before conversion and the detection value after conversion can be selected from, for example, the motor input and the motor output, the motor input and the input of the linear motion device 5, the motor input and the output of the linear motion device 5, the motor input and the output of the output shaft 6, the motor output and the input of the linear motion device 5, the motor output and the output of the linear motion device 5, the motor output and the output of the output shaft 6, the input of the linear motion device 5 and the output of the linear motion device 5, the input of the linear motion device 5 and the output of the output shaft 6, or the output of the linear motion device 5 and the output of the output shaft 6. For example, the abnormality detection unit 14 can detect an abnormal state of the power unit 9A based on the detection value of the state of the motor 2 and the detection value of the state of the output shaft 6. The abnormal state of the power unit 9A is, for example, a stuck state or a high load state of the power transmission system such as the motor 2, the gears of the reducers 3A to 3C, or the linear motion parts of the linear motion device 5, a chipped or detached gear of the reducers 3A to 3C, etc.

[0057] At this time, in order to detect the state of the power unit 9A based on the detection value before and after conversion of the signal or motion converted by the power unit 9A, the estimation unit 14A can calculate an estimated value to be estimated as the state after conversion of the signal or motion converted by the power unit 9A based on the detection value before conversion of the signal or motion converted by the power unit 9A. For example, the estimation unit 14A can calculate an estimated value to be estimated as the state of the output shaft 6 based on the detection value of the state of the motor 2. Then, the abnormality detection unit 14 can detect the abnormal state of the power unit 9A based on the comparison result between the detection value of the state of the output shaft 6 and the estimated value estimated as the state of the output shaft 6 from the detection value of the state of the motor 2.

[0058] In order to detect the state of the power unit 9A based on the detection value before and after conversion of the signal or motion converted by the power unit 9A, the estimation unit 14A may calculate an estimated value estimated as the state before conversion of the signal or motion converted by the power unit 9A based on the detection value after conversion of the signal or motion converted by the power unit 9A. For example, the estimation unit 14A may calculate an estimated value estimated as the state of the motor 2 based on the detection value of the state of the output shaft 6. Then, the abnormality detection unit 14 may detect the abnormal state of the power unit 9A based on the result of comparison between the detection value of the state of the motor 2 and the estimated value estimated as the state of the motor 2 from the detection value of the state of the output shaft 6.

[0059] The abnormality output unit 15 outputs the detection result of the abnormal state of the power unit 9A. The abnormal state of the power unit 9A is, for example, a stuck state or a high load state of the power transmission system such as the motor 2, the gears of the reducers 3A to 3C, or the linear motion parts of the linear motion device 5, or a chipped or dislocated gear of the reducers 3A to 3C.

[0060] The motor 2 performs rotational motion based on a driving current input from the motor control unit 11. At this time, the motor 2 can be used as a drive source for the linear motion device 5. The rotational position sensor 2A detects the rotational position of the motor 2. The reducers 3A to 3C generate an input for the linear motion device 5 based on the output of the motor 2. The reducers 3A to 3C can include gears that convert the rotation speed of the motor 2 and input it to the linear motion device 5. The bearing 4 supports the screw shaft 5A so that the screw shaft 5A can rotate based on the input from the reducers 3A to 3C.

[0061] The linear motion device 5 converts the rotational motion of the screw shaft 5A into the linear motion of the nut 5B. At this time, the rotational motion is input from the reducers 3A to 3C to the linear motion device 5, and the linear motion device 5 outputs an axial force to the output shaft 6. The linear motion device 5 is, for example, a ball screw in which the screw shaft 5A and the nut 5B are screwed together.

[0062] The output shaft 6 outputs an axial force based on the linear motion converted by the nut 5B. The output shaft 6 is shaped, for example, cylindrical, into which the screw shaft 5A can be inserted. The connecting portion 5C connects the linear motion device 5 and the output shaft 6. The connecting portion 5C may be a cotter that penetrates the side surface of the output shaft 6 and can be fitted into the nut 5B, an electromagnetic clutch or an electromagnetic brake, or a clamping mechanism using air pressure, hydraulic pressure, or an actuator.

[0063] The sensor 7A detects the state of the output shaft 6. The sensor 7A can be used as a second sensor that detects the state of the output member driven via the intermediate member according to the output state of the drive source. The state of the output shaft 6 may be the axial force output from the output shaft 6, the position of the output shaft 6, the speed of the output shaft 6, or the acceleration of the output shaft 6. In this case, an axial force sensor, a position sensor, a speed sensor, or an acceleration sensor can be used as the sensor 7A. The rotational position sensor 2A and the current sensor 13 can be used to detect the state of the motor 2.

[0064] The detection value of the rotational position of motor 2 detected by rotational position sensor 2A is input to motor angle calculation unit 12. Then, motor angle calculation unit 12 calculates a motor angle based on the detection value of the rotational position of motor 2, and inputs it to motor control unit 11 and abnormality detection unit 14. A drive current that drives motor 2 is detected by current sensor 13, and the detection value of the drive current is input to motor control unit 11 and abnormality detection unit 14.

[0065] Then, in the motor control unit 11, based on the detected value of the drive current and the detected value of the rotational position of the motor 2, the drive current of the motor 2 is controlled, and the rotational motion of the motor 2 is controlled. The rotational motion of the motor 2 is decelerated by the reducers 3A to 3C, and then input to the linear motion device 5. Then, in the linear motion device 5, the rotational motion input to the linear motion device 5 is converted into linear motion, and is output to the output shaft 6 via the connecting part 5C.

[0066] This electric actuator can be used, for example, in a vibration damping device for a vehicle. For example, in the case of a vibration damping device for a railway vehicle, the electric actuator can be installed between the car body and the bogie. Then, by outputting an axial force in the opposite phase to the vibration of the car body from the output shaft 6, the vibration of the car body can be reduced.

[0067] At this time, the sensor 7A detects the state of the output shaft 6, and the detection value of the state of the output shaft 6 is input to the abnormality detection unit 14. Then, in the abnormality detection unit 14, an estimated value which is an estimated state of the output shaft 6 is calculated based on the detection value of the state of the motor 2, and the detection value of the state of the output shaft 6 is compared with the estimated value which is an estimated state of the output shaft 6. Then, in the abnormality detection unit 14, an abnormal state of the power unit 9A is detected based on the comparison result between the detection value of the state of the output shaft 6 and the estimated value which is an estimated state of the output shaft 6. When the abnormality detection unit 14 detects an abnormal state of the power unit 9A, the detection result of the abnormal state of the power unit 9A is output to the higher-level device 8 via the abnormality output unit 15. The higher-level device 8 can notify the user of the detection result of the abnormal state of the power unit 9A, for example, by displaying the detection result of the abnormal state of the power unit 9A.

[0068] Furthermore, when the abnormality detection unit 14 detects an abnormal state of the power unit 9A, control data is output to the motor control unit 11. At this time, the motor control unit 11 can stop the motor 2 or decelerate the motor 2 based on the control data output from the abnormality detection unit 14.

[0069] Here, the abnormality detection unit 14 detects an abnormal state of the power unit 9A based on the detection value before and after conversion of the signal or motion converted by the power unit 9A, thereby enabling the electric actuator to detect abnormalities alone while easing restrictions on the locations or states where abnormalities in the power unit 9A can be detected. This makes it possible to improve the diversity and flexibility of data processing or data acquisition required for detecting abnormalities in the power unit 9A, and to achieve high accuracy and efficiency in abnormality analysis of the electric actuator.

[0070] Furthermore, by providing the linear motion device 5 to the electric actuator, it is possible to obtain a large axial output from a relatively small input torque, making it possible to use the electric actuator as a vibration damping device for a vehicle while suppressing an increase in size, and also making it possible to detect abnormalities in the linear motion device 5 and the output shaft 6 beyond the motor 2. Therefore, even in cases where a high level of safety is required, the electric actuator can be applied without increasing the difficulty of handling and installing the electric actuator.

[0071] In addition, by using the detection value of the current sensor 13 or the detection value of the rotational position sensor 2A not only for motor control but also for abnormality detection, it becomes possible to detect an abnormal state of the power unit 9A without providing a separate sensor dedicated to abnormality detection. This makes it possible to improve the accuracy and efficiency of abnormality analysis while suppressing the increase in size and cost of the electric actuator.

[0072] FIG. 2 is a block diagram showing an example of a hardware configuration of a data processing unit used in the control device of FIG. 2, the data processing unit 100 includes a processor 101, a communication control device 102, a communication interface 103, a primary storage device 104, an auxiliary storage device 105, and an input / output interface 107. The processor 101, the communication control device 102, the communication interface 103, the primary storage device 104, the auxiliary storage device 105, and the input / output interface 107 are connected to each other via an internal bus 106. The primary storage device 104 and the auxiliary storage device 105 are accessible from the processor 101.

[0073] In addition, an inverter 111, a sensor 112, an input device 113, and an output device 114 are provided outside the data processing unit 100. The inverter 111, the sensor 112, the input device 113, and the output device 114 are connected to the internal bus 106 via an input / output interface 107. The input device 113 and the output device 114 can be used as a human interface.

[0074] The input device 113 is, for example, a keyboard, a mouse, a touch panel, a card reader, a voice input device, etc. The output device 114 is, for example, a screen display device (a liquid crystal monitor, an organic EL (Electro Luminescence) display, a graphic card, etc.), a voice output device (a speaker, etc.), a printer, etc.

[0075] The inverter 111 generates a drive current for the motor 2 based on a command from the processor 101. At this time, the inverter 111 can, for example, perform PWM (Pulse Width Modulation) control on the motor 2. The sensor 112 detects the state of the motor 2, the state of the linear motion device 5, and the state of the output shaft 6 in Fig. 1. The sensor 112 is, for example, the rotational position sensor 2A, the current sensor 13, and the sensor 7A in Fig. 1.

[0076] The processor 101 is hardware that controls the operation of the entire data processing unit 100. The processor 101 may be a central processing unit (CPU) or a graphics processing unit (GPU). The processor 101 may be a single-core processor or a multi-core processor. The processor 101 may include a hardware circuit such as an accelerator that performs part of the processing (for example, a field-programmable gate array (FPGA) or an application specific integrated circuit (ASIC)). The processor 101 may operate as a neural network.

[0077] The primary storage device 104 can be composed of, for example, a semiconductor memory such as a static random access memory (SRAM) or a dynamic random access memory (DRAM). The primary storage device 104 can store programs being executed by the processor 101 and can provide a work area for the processor 101 to execute the programs.

[0078] The auxiliary storage device 105 is a storage device with a large storage capacity, such as a hard disk device or a solid state drive (SSD). The auxiliary storage device 105 can hold executable files of various programs and data used to execute the programs. The auxiliary storage device 105 can store a state detection program 105A. The state detection program 105A may be software that can be installed in the data processing unit 100, or may be incorporated in the data processing unit 100 as firmware.

[0079] The communication control device 102 is hardware having a function of controlling communication with the outside. The communication control device 102 is connected to a network 109 via a communication interface 103. The network 109 may be the Internet or a Wide Area Network (WAN), a Local Area Network (LAN) such as WiFi or Ethernet (registered trademark), or a mixture of the Internet, a WAN, and a LAN.

[0080] The input / output interface 107 converts data input from the sensor 112 and the input device 113 into a data format that can be processed by the processor 101, converts data output from the processor 101 into a data format that can be processed by the inverter 111, and converts data output from the processor 101 into a data format that can be processed by the output device 114.

[0081] The processor 101 reads the state detection program 105A into the main storage device 104 and executes the state detection program 105A, thereby making it possible to detect an abnormal state of the power unit 9A based on the detection value before conversion of the signal or motion converted by the power unit 9A in Fig. 1. For example, the processor 10 can calculate an estimated value to be estimated as the state of the output shaft 6 based on the detection value of the state of the motor 2. The processor 10 can then detect an abnormal state of the power unit 9A based on the comparison result between the detection value of the state of the output shaft 6 and the estimated value estimated as the state of the output shaft 6 from the detection value of the state of the motor 2. At this time, the processor 101 can obtain the detection value before replacement and the detection value after conversion from the sensor 112.

[0082] The execution of the state detection program 105A may be shared among multiple processors or computers. Alternatively, the processor 101 may instruct a cloud computer or the like to execute all or part of the state detection program 105A via the network 109 and receive the execution result.

[0083] This data processing unit 100 can be provided in the control device 1 of Fig. 1. In this case, the data processing unit 100 can take on functions realized in the control device 1 by software or firmware.

[0084] Fig. 3 is a flow chart showing an example of an abnormality detection process for the electric actuator of Fig. 1. Each step of Fig. 3 is realized by the processor 101 reading and executing a program stored in the auxiliary storage device 105 of Fig. 2. At this time, the processor 101 of Fig. 2 can function as the abnormality detection unit 14 and the abnormality output unit 15 of Fig. 1.

[0085] 3, the processor 101 in FIG. 2 acquires a detection value of the drive current of the motor 2 in FIG. 1 from the current sensor 13 (S11). Next, the processor 101 acquires from the sensor 7A the detection value of the axial force output from the output shaft 6 (S12). At this time, an axial force sensor can be used as the sensor 7A. Next, the processor 101 calculates an estimate of the axial force of the output shaft 6 based on the detection value of the drive current of the motor 2 acquired in S11 (S13). At this time, the processor 101 can calculate the estimate of the axial force based on, for example, the formula: drive current x motor coefficient x gear ratio of the reducer x movement amount of the ball screw.

[0086] Next, the processor 101 compares the detected value of the axial force obtained in S12 with the estimated value of the axial force calculated in S13 (S14). Next, the processor 101 determines whether the difference between the detected value and the estimated value of the axial force is equal to or greater than the threshold value (S15). If the difference between the detected value and the estimated value of the axial force is not equal to or greater than the threshold value, the processor 101 returns to the process of S11. On the other hand, if the difference between the detected value and the estimated value of the axial force is equal to or greater than the threshold value, the processor 101 notifies the electric actuator of an abnormality (S16). Next, the processor 101 outputs a command to stop or decelerate the motor 2 to the inverter 111 (S17).

[0087] This allows the processor 101 to detect an abnormal state in the power transmission system from the motor 2 to the output shaft 6 by detecting the drive current of the motor 2 and the axial force output from the output shaft 6, while enabling control of the axial force output from the output shaft 6 based on the drive current of the motor 2. This makes it possible to improve the safety and maintainability of the electric actuator during use while preventing the mechanical configuration of the electric actuator from becoming too complicated.

[0088] In addition, by using the current sensor 13 for motor control also for abnormality detection, it becomes possible to detect an abnormal state of the power unit 9A without providing a separate current sensor for abnormality detection. This makes it possible to improve the accuracy and efficiency of abnormality analysis while suppressing the increase in size and cost of the electric actuator.

[0089] Fig. 4 is a flowchart showing another example of the abnormality detection process of the electric actuator of Fig. 1. Here, the processor 101 can realize the process of Fig. 4 by executing a program for realizing the process of Fig. 4 instead of the program for realizing the process of Fig. 3. In FIG. 4, the processor 101 acquires a detection value of the drive current of the motor 2 in FIG. 1 from the current sensor 13 (S21). Next, the processor 101 acquires a detection value of the position of the output shaft 6 from the sensor 7A (S22). At this time, a position sensor can be used as the sensor 7A. Next, the processor 101 calculates an estimated value of the position of the output shaft 6 based on the detected value of the drive current of the motor 2 acquired in S21 (S23).

[0090] Next, the processor 101 compares the detected value of the position of the output shaft 6 acquired in S22 with the estimated value of the position of the output shaft 6 calculated in S23 (S24). Next, the processor 101 determines whether the difference between the detected value and the estimated value of the position of the output shaft 6 is equal to or greater than the threshold value (S25). If the difference between the detected value and the estimated value of the position of the output shaft 6 is not equal to or greater than the threshold value, the processor 101 returns to the process of S21. On the other hand, if the difference between the detected value and the estimated value of the position of the output shaft 6 is equal to or greater than the threshold value, the processor 101 notifies the abnormality of the electric actuator (S26). Next, the processor 101 outputs a command to stop or decelerate the motor 2 to the inverter 111 (S27).

[0091] This allows the processor 101 to detect an abnormal state in the power transmission system from the motor 2 to the output shaft 6 by detecting the drive current of the motor 2 and the position of the output shaft 6, while enabling control of the position of the output shaft 6 based on the drive current of the motor 2. This makes it possible to improve the safety and maintainability of the electric actuator during use while preventing the mechanical configuration of the electric actuator from becoming too complicated.

[0092] Fig. 5 is a flowchart showing yet another example of the abnormality detection process of the electric actuator of Fig. 1. Here, the processor 101 can realize the process of Fig. 5 by executing a program realizing the process of Fig. 5 instead of the program realizing the process of Fig. 3 or Fig. 4. In FIG. 5, the processor 101 acquires a detection value of the rotational position of the motor 2 in FIG. 1 from the rotational position sensor 2A (S31). Next, the processor 101 acquires the position of the output shaft 6 from the sensor 7A (S32). At this time, a position sensor can be used as the sensor 7A. Next, the processor 101 calculates an estimated value of the position of the output shaft 6 based on the detected value of the rotational position of the motor 2 acquired in S31 (S33).

[0093] Next, the processor 101 compares the detected value of the position of the output shaft 6 acquired in S32 with the estimated value of the position of the output shaft 6 calculated in S33 (S34). Next, the processor 101 determines whether the difference between the detected value and the estimated value of the position of the output shaft 6 is equal to or greater than the threshold value (S35). If the difference between the detected value and the estimated value of the position of the output shaft 6 is not equal to or greater than the threshold value, the processor 101 returns to the process of S31. On the other hand, if the difference between the detected value and the estimated value of the position of the output shaft 6 is equal to or greater than the threshold value, the processor 101 notifies the abnormality of the electric actuator (S36). Next, the processor 101 outputs a command to stop or decelerate the motor 2 to the inverter 111 (S37).

[0094] This allows the processor 101 to detect an abnormal state in the power transmission system from the motor 2 to the output shaft 6 by detecting the rotational position of the motor 2 and the position of the output shaft 6 while enabling control of the position of the output shaft 6 based on the rotational motion of the motor 2. This makes it possible to improve the safety and maintainability of the electric actuator during use while preventing the mechanical configuration of the electric actuator from becoming too complicated.

[0095] In addition, by using the rotational position sensor 2A for motor control also for abnormality detection, it becomes possible to detect an abnormal state of the power unit 9A without providing a separate rotational position sensor for abnormality detection. This makes it possible to improve the accuracy and efficiency of abnormality analysis while suppressing the increase in size and cost of the electric actuator.

[0096] The processor 101 may execute at least two of the processes in Figures 4, 5, and 6 in parallel. In this case, if an abnormality is detected in at least one of the processes in Figures 4, 5, and 6, it may be determined that the electric actuator is abnormal. This makes it possible to determine that the electric actuator is abnormal even if the rotational position sensor 2A, the current sensor 13, or the axial force sensor or position sensor used as the sensor 7A fails, thereby improving the robustness of the electric actuator.

[0097] FIG. 6 is a block diagram showing the configuration of an electric actuator according to the second embodiment. In FIG. 6, this electric actuator includes a power unit 9B instead of the power unit 9A in FIG. 1. In the power unit 9A in FIG. 1, the sensor 7A is directly installed on the output shaft 6, whereas in the power unit 9B, the sensor 7B is installed apart from the output shaft 6. The sensor 7B can be used as a position sensor that detects the position of the output shaft 6. In this case, the sensor 7B can be a remote sensor or a non-contact sensor such as an infrared sensor, an ultrasonic sensor, or an image sensor. The sensor 7B may be disposed, for example, coaxially with the output shaft 6. The electric actuator in FIG. 6 can be configured and operated in the same manner as the electric actuator in FIG. 1, except that the sensor 7B is used instead of the sensor 7A.

[0098] Here, by using a remote sensor or a non-contact sensor as the sensor 7B to detect the position of the output shaft 6, it becomes unnecessary to directly install the sensor 7B on the output shaft 6. Therefore, even if the space for directly installing the sensor 7B on the output shaft 6 cannot be secured, it becomes possible to detect the position of the output shaft 6.

[0099] 7 is a block diagram showing the configuration of an electric actuator according to a third embodiment. In the first embodiment, the state of the path from the driving source to the output member is detected based on a comparison result between an estimated value, which is an estimated state of the output member from a detection value of the output state of the driving source, and a detection value of the state of the output member driven via an intermediate member according to the output state of the driving source. In the third embodiment, the state of the path from the driving source to the output member is detected based on a comparison result between an estimated value, which is an estimated state of the intermediate member from a detection value of the output state of the driving source, and a detection value of the state of the intermediate member interposed between the driving source and the output member.

[0100] In FIG. 7, this electric actuator includes a power unit 9C instead of the power unit 9A in FIG. 1. The power unit 9C includes a sensor 7C instead of the sensor 7A in FIG. 1. The sensor 7C can detect the input torque input from the reduction gear 3C to the linear motion device 5. The sensor 7C can be installed, for example, on the gear of the reduction gear 3C. In this case, the sensor 7C can be, for example, a strain gauge. The electric actuator in FIG. 7 can be configured and operated in the same manner as the electric actuator in FIG. 1, except that the sensor 7C is used instead of the sensor 7A.

[0101] For example, the estimation unit 14A can calculate an estimated value to be estimated as the state of the reducer 3C based on the detection value of the state of the motor 2. Then, the abnormality detection unit 14 can detect an abnormal state of the power unit 9A based on a comparison result between the detection value of the state of the reducer 3C and the estimated value to be estimated as the state of the reducer 3C from the detection value of the state of the motor 2.

[0102] Alternatively, the estimation unit 14A may calculate an estimated value to be estimated as the state of the linear motion device 5 based on the detection value of the state of the motor 2. Then, the abnormality detection unit 14 may detect an abnormal state of the power unit 9A based on a comparison result between the detection value of the state of the linear motion device 5 and the estimated value to be estimated as the state of the linear motion device 5 from the detection value of the state of the motor 2.

[0103] Fig. 8 is a flowchart showing an example of an abnormality detection process for the electric actuator of Fig. 7. Here, the processor 101 of Fig. 2 can realize the process of Fig. 8 by executing a program realizing the process of Fig. 8 instead of the program realizing the process of Fig. 3, Fig. 4 or Fig. 5. In FIG. 8, the processor 101 acquires a detection value of the drive current of the motor 2 in FIG. 1 from the current sensor 13 (S41). Next, the processor 101 acquires a detection value of the input torque input to the linear motion device 5 from the sensor 7C (S42). Next, the processor 101 calculates an estimate of the input torque input to the linear motion device 5 based on the detection value of the drive current of the motor 2 acquired in S41 (S43).

[0104] Next, the processor 101 compares the detected value of the input torque obtained in S42 with the estimated value of the input torque calculated in S43 (S44). Next, the processor 101 determines whether the difference between the detected value and the estimated value of the input torque is equal to or greater than the threshold (S45). If the difference between the detected value and the estimated value of the input torque is not equal to or greater than the threshold, the processor 101 returns to the process of S41. On the other hand, if the difference between the detected value and the estimated value of the input torque is equal to or greater than the threshold, the processor 101 notifies the abnormality of the electric actuator (S46). Next, the processor 101 outputs a command to stop or decelerate the motor 2 to the inverter 111 (S47).

[0105] This allows the processor 101 to detect an abnormal state in the power transmission system from the motor 2 to the linear motion device 5 by detecting the drive current of the motor 2 and the input torque of the linear motion device 5 while enabling control of the input torque output from the reducer 3C based on the drive current of the motor. This makes it possible to improve the safety and maintainability of the electric actuator during use while preventing the mechanical configuration of the actuator from becoming complicated.

[0106] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and includes various modified examples. For example, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace a part of the configuration of each embodiment with another configuration.

[0107] For example, in the above-described embodiment, the power unit 9A includes the motor 2, the reducers 3A to 3C, the linear motion device 5, and the output shaft 6, but may have other configurations. For example, the power unit 9A may include a linear guide instead of the output shaft 6, or may include a link mechanism or an arm mechanism.

[0108] In addition, the state of the path from the driving source to the output member may be detected based on the comparison result between an estimated value, which is an inferred state of the output member from a detection value of the state of an intermediate member interposed between the driving source and the output member, and a detection value of the state of the output member driven via the intermediate member in accordance with the output state of the driving source.

[0109] For example, the estimation unit 14A can calculate an estimated value to be estimated as the state of the output shaft 6 based on the detected value of the state of the reducer 3C. Then, the abnormality detection unit 14 can detect an abnormal state of the power unit 9A based on a comparison result between the detected value of the state of the output shaft 6 and the estimated value to be estimated as the state of the output shaft 6 from the detected value of the state of the reducer 3C.

[0110] Alternatively, the estimation unit 14A may calculate an estimated value to be estimated as the state of the output shaft 6 based on the detection value of the state of the linear motion device 5. Then, the abnormality detection unit 14 may detect an abnormal state of the power unit 9A based on a comparison result between the detection value of the state of the output shaft 6 and the estimated value to be estimated as the state of the output shaft 6 from the detection value of the state of the linear motion device 5. [Explanation of symbols]

[0111] 1 control device, 2 motor, 3A to 3C reducer, 4 bearing, 5 linear motion device, 5A screw shaft, 5B nut, 5C connecting section, 6 output shaft, 7A sensor, 8 host device, 9A power section, 11 motor control section, 12 motor angle calculation section, 13 current sensor, 14 abnormality detection section, 15 abnormality output section

Claims

1. A power unit that generates power; a state detection unit that detects a state of the power unit based on a detection value before and a detection value after the conversion of the signal or motion converted by the power unit, The power unit includes: A motor; a linear motion device that performs linear motion based on the rotational motion of the motor; an output shaft that outputs an axial force based on the linear motion of the linear motion device; The state detection unit detects the state of the power unit based on a comparison result between an estimated value of the axial force estimated from a detected value of a drive current of the motor and a detected value of the axial force output from the output shaft. An electric actuator characterized by:

2. The electric actuator according to claim 1, further comprising an output section that outputs a detection result of the state of the power section.

3. 3. The electric actuator according to claim 1, further comprising a motor control unit that controls the motor based on a detected value of a drive current of the motor and a detected value of a rotational position of the motor.

4. 4. The electric actuator according to claim 3, wherein the motor control unit controls the motor based on a detection result of an abnormal state of the power unit.

5. 5. The electric actuator according to claim 1, wherein the state detection unit detects an abnormal state of the power unit based on at least two of detection values ​​of a state of the motor, a detection value of a state of the linear motion device, and a detection value of a state of the output shaft.

6. a current sensor for detecting a drive current of the motor; The electric actuator according to claim 1 , further comprising an axial force sensor for detecting the axial force.

7. 7. The electric actuator according to claim 1, wherein the state detection unit detects the state of the power unit based on a comparison result between an estimated value of the position of the output shaft, which is estimated from a detection value of the drive current of the motor, and a detection value of the position of the output shaft.

8. a current sensor for detecting a drive current of the motor; The electric actuator according to claim 7, further comprising a position sensor for detecting a position of the output shaft.

9. 9. The electric actuator of claim 8, wherein the position sensor is a remote sensor.

10. 10. The electric actuator according to claim 1, wherein the state detection unit detects the state of the power unit based on a comparison result between an estimated value of the position of the output shaft estimated from a detection value of the rotational position of the motor and the detection value of the position of the output shaft.

11. a rotational position sensor for detecting a rotational position of the motor; The electric actuator according to claim 10, further comprising a position sensor for detecting a position of the output shaft.

12. A power unit that generates power; a state detection unit that detects a state of the power unit based on a detection value before and a detection value after the conversion of the signal or motion converted by the power unit, The power unit includes: A motor; a linear motion device that performs linear motion based on the rotational motion of the motor; an output shaft that outputs an axial force based on the linear motion of the linear motion device; an electric actuator characterized in that the state detection unit detects the state of the power unit based on a comparison result between an estimated value of an input torque of the linear motion device, which is estimated from a detected value of the drive current of the motor, and a detected value of the input torque of the linear motion device.

13. a current sensor for detecting a drive current of the motor; The electric actuator according to claim 12, further comprising a torque sensor for detecting an input torque of the linear motion device.

14. A reducer is further provided to generate an input to the linear motion device based on an output of the motor. The electric actuator according to claim 13, wherein the torque sensor is disposed in the reduction gear.

15. 15. The electric actuator according to claim 1, which is applied to a vibration damping device.

16. A drive source that generates power; a linear motion device that performs linear motion based on the rotational motion of the drive source; an output shaft that outputs an axial force based on the linear motion of the linear motion device; A first sensor for detecting an output state of the driving source; A second sensor for detecting a state of the output shaft; an estimation unit that calculates an estimated value that is an estimated state of the output shaft based on a detection value of the first sensor; an electric actuator comprising: a state detection unit that detects a state of a path from the drive source to the output shaft based on a comparison result between the estimated value and the detection value of the second sensor.

17. A control unit that controls a power unit that generates power; a state detection unit that detects a state of the power unit based on a detection value before and a detection value after the signal or motion converted by the power unit, The power unit includes: A motor; a linear motion device that performs linear motion based on the rotational motion of the motor; an output shaft that outputs an axial force based on the linear motion of the linear motion device; The state detection unit detects the state of the power unit based on a comparison result between an estimated value of the axial force estimated from a detected value of a drive current of the motor and a detected value of the axial force output from the output shaft. A control device comprising:

18. A program used for an electric actuator having a power unit that generates power and a computer, The power unit includes: A motor; a linear motion device that performs linear motion based on the rotational motion of the motor; an output shaft that outputs an axial force based on the linear motion of the linear motion device, obtaining a detection value of a drive current of the motor; acquiring a detection value of the axial force output from the output shaft; and detecting a state of the power unit based on a comparison result between an estimated value of the axial force estimated from a detected value of the drive current of the motor and a detected value of the axial force output from the output shaft.

Images