Failure detection device

Abstract

To provide a failure detection device capable of more accurately detecting a failure.SOLUTION: The failure detection device 70 includes a first acquisition unit 71 that acquires a measurement value measured by the angle sensor 50 that measures the swing angle of the swing body 30, a second acquisition unit 72 that acquires estimation information for estimating the swing angle, an estimation unit 73 that estimates the swing angle based on the estimation information acquired by the second acquisition unit 72, a calculation unit 74 that calculates a difference between the measurement value acquired by the first acquisition unit 71 and an estimation value of the swing angle estimated by the estimation unit 73, and a determination unit 75 that determines that a failure has occurred when the difference calculated by the calculation unit 74 is equal to or greater than a predetermined value in a predetermined period.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a failure detection device that detects a failure. [Background technology]

[0002] An angle sensor is provided to measure the rotation angle of a rotating body such as the cab of a construction machine. Devices for detecting malfunctions of angle sensors are also known. For example, Patent Document 1 discloses a device that determines that a rotation angle sensor is malfunctioning when the output value of a signal from the rotation angle sensor that detects the rotation angle of a boom is outside a predetermined range and has been output for more than a predetermined time. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-167194 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the device of Patent Document 1 has the problem that it cannot detect a fault even if it occurs if the output value of the output signal of the turning angle sensor is within a predetermined range, and therefore cannot detect the fault accurately.

[0005] The present invention has been made in view of the above-mentioned problems, and has an object to provide a failure detection device that can detect failures with higher accuracy. [Means for solving the problem]

[0006] The first invention for solving the above problem is characterized by comprising a first acquisition unit that acquires a measurement value measured by an angle sensor that measures the rotation angle of a rotating body, a second acquisition unit that acquires estimated information for estimating the rotation angle, an estimation unit that estimates the rotation angle based on the estimated information acquired by the second acquisition unit, a calculation unit that calculates the difference between the measurement value acquired by the first acquisition unit and the estimated value of the rotation angle estimated by the estimation unit, and a determination unit that determines that a malfunction has occurred if the difference calculated by the calculation unit is equal to or greater than a predetermined value for a predetermined period of time.

[0007] In the present invention, a malfunction is determined to have occurred if the difference between the measured value of the turning angle measured by the angle sensor and the estimated value of the turning angle estimated by the estimation unit is greater than or equal to a predetermined value for a predetermined period of time, thereby enabling more accurate detection of malfunctions.

[0008] The estimated information may include information measured by an encoder provided for a motor that rotates the rotating body.

[0009] This makes it possible to easily estimate the rotation angle of the rotating body based on information measured by an encoder provided on the motor that rotates the rotating body, thereby making it easy to detect malfunctions.

[0010] The estimated information may include information measured by a current sensor that measures a current supplied to an electric motor that rotates the rotating body.

[0011] This makes it possible to easily estimate the rotation angle of the rotating body based on information measured by a current sensor that measures the current supplied to the electric motor that rotates the rotating body, making it easy to detect malfunctions.

[0012] The estimated information may include information measured by a flow rate sensor that measures the flow rate of hydraulic oil supplied to a hydraulic motor that rotates the rotating body.

[0013] This makes it easy to estimate the rotation angle of the rotating body based on information measured by a flow sensor that measures the flow rate of hydraulic oil supplied to the hydraulic motor that rotates the rotating body, making it easy to detect malfunctions.

[0014] The estimated information may include information measured by a differential pressure sensor that measures the differential pressure of a valve for controlling a hydraulic motor that rotates the rotating body, and information measured by an opening amount sensor that measures the opening amount of the valve.

[0015] This makes it easy to estimate the rotation angle of the rotating body based on information measured by a differential pressure sensor that measures the differential pressure of a valve for controlling the hydraulic motor that rotates the rotating body, and information measured by an opening amount sensor that measures the opening amount of the valve, making it easy to detect malfunctions. [Effects of the Invention]

[0016] According to the present invention, it is possible to provide a failure detection device that can detect failures with higher accuracy. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a diagram showing a construction machine 10. FIG. [Figure 2] FIG. [Figure 3] FIG. 2 is a block diagram showing the functional configuration of the construction machine 10. [Figure 4] 4 is a flowchart showing an example of the operation of the failure detection device 70. [Figure 5] FIG. 10 is a diagram for explaining another example of estimated information. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0019] Fig. 1 is a diagram showing a construction machine 10 equipped with a fault detection device according to an embodiment of the present invention. The fault detection device will be described in detail later. As shown in Fig. 1, the construction machine 10 is a backhoe, and is equipped with a running body 20 and a revolving body 30.

[0020] The running body 20 runs on the ground, etc. The running body 20 runs on the ground, etc., causing the construction machine 10 to move. For example, the running body 20 is configured by a caterpillar, etc.

[0021] The rotating unit 30 rotates relative to the running unit 20. The rotating unit 30 has a rotating section 31, a cab 32, and a shovel section 33. The rotating section 31 is rotatably connected to the running unit 20 via a rotating shaft 35 (described later) and the like. When the rotating section 31 rotates, the cab 32 and the shovel section 33 rotate. The cab 32 is a control cabinet in which an operator who operates the construction machine 10 sits. While seated in the cab 32, the operator performs various tasks by traveling the running unit 20, rotating the rotating unit 30, and operating the shovel section 33.

[0022] 2 is a diagram showing the motor 40 etc. As shown in Fig. 2, the construction machine 10 further includes the motor 40. In addition, the revolving body 30 further includes a revolving gear 34 and a revolving shaft 35.

[0023] The motor 40 is a rotation motor for rotating the rotating body 30. The motor 40 has a gear 41 having teeth (not shown) that mesh with teeth (not shown) formed on the inner periphery of the rotation gear 34.

[0024] The swivel gear 34 is connected to the swivel shaft 35. The swivel shaft 35 is rotatably supported on the traveling body 20. When the motor 40 rotates, the swivel gear 34 and the swivel shaft 35 rotate about the swivel axis A. When the swivel gear 34 and the swivel shaft 35 rotate, the swivel unit 31 and the like rotate about the swivel axis A.

[0025] 3 is a block diagram showing the functional configuration of the construction machine 10. As shown in FIG. 3, the construction machine 10 further includes an angle sensor 50, an encoder 60, and a failure detection device 70.

[0026] The angle sensor 50 measures the rotation angle of the rotating unit 30. The angle sensor 50 is attached to the rotation shaft 35 or the like and measures the rotation angle of the rotating unit 30. For example, the angle sensor 50 is a magnetic, optical, or mechanical detector.

[0027] The encoder 60 is provided for the motor 40 in order to measure the rotation angle and the like of the motor 40. For example, the encoder 60 is an optical incremental encoder, which outputs a pulse signal as the motor 40 rotates.

[0028] The fault detection device 70 is a device that detects faults. The fault detection device 70 includes a first acquisition unit 71, a second acquisition unit 72, an estimation unit 73, a calculation unit 74, and a determination unit 75. For example, the first acquisition unit 71 and the second acquisition unit 72 are configured by a communication module or the like. The estimation unit 73, the calculation unit 74, and the determination unit 75 are configured by a processor, a memory, or the like. Various pieces of information for calculating the difference and the like are stored in memory (a storage unit such as an HDD (Hard Disk Drive)), and the processor reads the information stored in the memory and performs various processes such as calculating the difference.

[0029] The first acquisition unit 71 acquires the measurement value of the turning angle measured by the angle sensor 50. For example, the first acquisition unit 71 is capable of communicating directly or indirectly with the angle sensor 50 and acquires the measurement value output from the angle sensor 50.

[0030] The second acquisition unit 72 acquires estimated information for estimating the rotation angle of the rotating unit 30. For example, the estimated information is information measured by a sensor or the like that measures something other than the rotation angle of the rotating unit 30. Furthermore, for example, the sensor or the like is not newly installed for the purpose of fault detection by the fault detection device 70, but is originally installed in the construction machine 10 for another purpose. In this embodiment, the sensor or the like is the encoder 60, which is built into the motor 40 and is originally used for controlling the operation of the motor 40, but here is also used for fault detection by the fault detection device 70. The estimated information includes information measured by the encoder 60. For example, the second acquisition unit 72 can communicate directly or indirectly with the encoder 60 and acquires the information output from the encoder 60. For example, the information includes a pulse signal.

[0031] The estimation unit 73 estimates the turning angle based on the estimation information. As described above, in this embodiment, the estimation information includes the pulse signal measured by the encoder 60, and the estimation unit 73 estimates the turning angle based on the number of pulses serving as the origin and the current number of pulses.

[0032] For example, if the number of pulses at the origin is e0 [pulse], the current number of pulses is e [pulse], the resolution of the encoder 60 is S [rad / pulse], and the rotation angle of the motor 40 is θ1, the estimation unit 73 estimates the rotation angle of the motor 40 using θ1 = S × (e - e0).

[0033] Furthermore, if the speed ratio of the rotation of the rotating body 30 relative to the rotation of the motor 40 is η and the estimated rotation angle of the rotating body 30 is θ2, the estimation unit 73 estimates the rotation angle of the rotating body 30 using θ2 = η × θ1.

[0034] Note that a resolver or a magnetic sensor having a Hall element may be used instead of the encoder 60 to measure the rotation angle of the motor 40. When a resolver or a magnetic sensor is used, for example, the estimation unit 73 may estimate the rotation angle of the rotating body 30 by multiplying the rotation angle of the motor 40 measured by the resolver or the magnetic sensor by η.

[0035] The calculation unit 74 calculates the difference between the measurement value of the turning angle measured by the angle sensor 50 and the estimated value of the turning angle estimated by the estimation unit 73.

[0036] The determination unit 75 determines that a malfunction has occurred if the difference calculated by the calculation unit 74 is equal to or greater than a predetermined value for a predetermined period of time. That is, the determination unit 75 determines that a malfunction has occurred if the period during which the difference is equal to or greater than a predetermined value continues for a predetermined period of time. On the other hand, the determination unit 75 determines that a malfunction has not occurred if the difference calculated by the calculation unit 74 is not equal to or greater than a predetermined value for a predetermined period of time. That is, the determination unit 75 determines that a malfunction has not occurred if the period during which the difference is equal to or greater than a predetermined value does not continue for a predetermined period of time.

[0037] The determination unit 75 outputs the determination result. For example, the determination unit 75 outputs the determination result to a monitor or the like installed in the cab 32. This allows the operator in the cab 32 to recognize whether or not a malfunction has occurred. The determination unit 75 may output the determination result to a CPU (Central Processing Unit) or the like that controls the construction machine 10, and the CPU or the like may stop the operation of the construction machine 10 when it is determined that a malfunction has occurred.

[0038] Fig. 4 is a flowchart showing an example of the operation of the failure detection device 70. As shown in Fig. 4, the first acquisition unit 71 acquires the measurement value of the turning angle measured by the angle sensor 50 (step S1).

[0039] The second acquisition unit 72 acquires estimation information for estimating the turning angle (step S2).

[0040] The estimation unit 73 estimates the turning angle based on the estimation information acquired by the second acquisition unit 72 (step S3).

[0041] The calculation unit 74 calculates the difference between the measurement value acquired by the first acquisition unit 71 and the estimated value of the turning angle estimated by the estimation unit 73 (step S4).

[0042] The determination unit 75 determines whether the difference calculated by the calculation unit 74 is equal to or greater than a predetermined value for a predetermined period of time (step S5).

[0043] If the difference calculated by the calculation unit 74 is equal to or greater than a predetermined value for a predetermined period of time (Yes in step S5), the determination unit 75 determines that a malfunction has occurred (step S6), and ends the process.

[0044] If the difference calculated by the calculation unit 74 is not equal to or greater than the predetermined value for the predetermined period (No in step S5), the determination unit 75 does not determine that a malfunction has occurred and ends the process.

[0045] As described above, the failure detection device 70 can detect a failure using a swing angle calculated using information obtained from sensors already installed for other purposes, without adding a new sensor or the like specifically for failure detection. Furthermore, by estimating the swing angle using information obtained from the sensors or the like used for the other purpose, even if the accuracy of the estimated swing angle is somewhat poor, the necessary swing angle information itself can be accurately obtained by the angle sensor 50. Furthermore, the use of the failure detection device 70 enables more accurate detection of failures, thereby preventing work from being performed using the measurement value of a faulty angle sensor 50 and preventing the shovel unit 33 from being oriented incorrectly, resulting in failure to perform normal excavation. Furthermore, when performing automatic operation of the construction machine or performing safe operation of the construction machine, the use of the measurement value of a faulty angle sensor 50 can be prevented, allowing these operations to be performed appropriately.

[0046] As described above, the fault detection device 70 according to this embodiment includes a first acquisition unit 71 that acquires measurement values ​​measured by the angle sensor 50 that measures the rotation angle of the rotating body 30, a second acquisition unit 72 that acquires estimated information for estimating the rotation angle, an estimation unit 73 that estimates the rotation angle based on the estimated information acquired by the second acquisition unit 72, a calculation unit 74 that calculates the difference between the measurement value acquired by the first acquisition unit 71 and the estimated value of the rotation angle estimated by the estimation unit 73, and a determination unit 75 that determines that a fault has occurred if the difference calculated by the calculation unit 74 is equal to or greater than a predetermined value for a predetermined period of time.

[0047] As a result, if the difference between the measured value of the turning angle measured by the angle sensor 50 and the estimated value of the turning angle estimated by the estimation unit 73 is equal to or greater than a predetermined value for a predetermined period of time, it is determined that a malfunction has occurred, thereby enabling more accurate detection of malfunctions.

[0048] The estimated information also includes information measured by an encoder 60 provided for the motor 40 that rotates the rotating body 30.

[0049] This allows the rotation angle of the rotating body 30 to be easily estimated based on information measured by the encoder 60 provided for the motor 40 that rotates the rotating body 30, making it easy to detect malfunctions.

[0050] FIG. 5 is a diagram illustrating another example of the estimated information.

[0051] 5(a), if the motor 40 is an electric motor, the construction machine 10 may be equipped with a current sensor 60a that measures the current flowing through the motor 40. In this case, the estimated information may include information measured by the current sensor 60a, and the second acquisition unit 72 may acquire estimated information that includes this information. The current sensor 60a is originally used for controlling the operation of the motor 40, but here it is also used for fault detection by the fault detection device 70.

[0052] The estimation unit 73 may estimate the rotation angle based on information measured by the current sensor 60a. Here, the estimation unit 73 estimates the rotation speed of the motor 40 from the frequency of the current measured by the current sensor 60a, and estimates the rotation angle by solving a differential equation including the estimated rotation speed of the motor 40 using state estimation theory based on a Kalman filter. Normally, when calculating the rotation angle from the rotation speed of the motor 40, the rotation angle is estimated by integrating the rotation speed of the motor 40, but this method may result in accumulated errors. Therefore, here, instead of the usual integration method, the estimation unit 73 estimates the rotation angle by solving a differential equation including the estimated rotation speed of the motor 40 using state estimation theory based on a Kalman filter, as described above.

[0053] For example, if the current frequency is F, the number of poles of the motor 40 is P, and the rotation speed of the motor 40 is R1, the estimation unit 73 estimates the rotation speed of the motor 40 by R1=120×F÷P.

[0054] Furthermore, if the speed ratio of the rotating structure 30 to the motor 40 is η and the rotation speed of the rotating structure 30 is R2, the estimation unit 73 estimates the rotation speed of the rotating structure 30 by R2=η×R1.

[0055] Furthermore, if the estimated rotation angle of the rotating unit 30 is θ2, the time derivative of θ2 is θ2dot, the rotation angle of the rotating unit 30 measured by the angle sensor 50 is y, and the estimated gain is L (L>0), the estimation unit 73 estimates the rotation angle of the rotating unit 30 by solving the differential equation θ2dot=R2-L×(θ2-y) to find θ2.

[0056] The calculation unit 74 calculates the difference using θ2-y, and the determination unit 75 determines whether or not the difference is equal to or greater than a predetermined value for a predetermined period of time.

[0057] Thus, here, the estimated information includes information measured by the current sensor 60a that measures the current supplied to the motor 40 that rotates the rotating body 30.

[0058] This makes it easy to estimate the rotation angle of the rotating body 30 based on information measured by the current sensor 60a, which measures the current supplied to the motor 40 that rotates the rotating body 30, making it easy to detect malfunctions.

[0059] 5(b), if the motor 40 is a hydraulic motor, the construction machine 10 may be equipped with a flow rate sensor 60b that measures the flow rate of hydraulic oil supplied to the motor 40. In this case, the estimated information may include information measured by the flow rate sensor 60b, and the second acquisition unit 72 may acquire estimated information that includes this information. The flow rate sensor 60b is originally used for controlling the operation of the motor 40, but here it is also used for fault detection by the fault detection device 70.

[0060] The estimation unit 73 may estimate the rotation angle based on information measured by the flow rate sensor 60b. Here, the estimation unit 73 estimates the rotation speed of the motor 40 from the flow rate measured by the flow rate sensor 60b, and estimates the rotation angle by solving a differential equation including the estimated rotation speed of the motor 40 using state estimation theory with a Kalman filter. Normally, the rotation angle is estimated by integrating the rotation speed of the motor 40, but this method may result in accumulated errors. Therefore, here, instead of using the usual integration method, the estimation unit 73 estimates the rotation angle by solving a differential equation including the estimated rotation speed of the motor 40 using state estimation theory with a Kalman filter, as described above.

[0061] For example, if the flow rate measured by the flow sensor 60b is C, the conversion constant is ε, and the rotation speed of the rotating body 30 is R2, the estimation unit 73 estimates the rotation speed of the rotating body 30 using R2 = ε × C.

[0062] Furthermore, if the estimated rotation angle of the rotating unit 30 is θ2, the time derivative of θ2 is θ2dot, the rotation angle of the rotating unit 30 measured by the angle sensor 50 is y, and the estimated gain is L (L>0), the estimation unit 73 estimates the rotation angle of the rotating unit 30 by solving the differential equation θ2dot=R2-L×(θ2-y) to find θ2.

[0063] The calculation unit 74 calculates the difference using θ2-y, and the determination unit 75 determines whether or not the difference is equal to or greater than a predetermined value for a predetermined period of time.

[0064] Thus, here, the estimated information includes information measured by the flow rate sensor 60b that measures the flow rate of the hydraulic oil supplied to the motor 40 that rotates the rotating body 30.

[0065] This makes it easy to estimate the rotation angle of the rotating body 30 based on information measured by the flow sensor 60b, which measures the flow rate of hydraulic oil supplied to the motor 40 that rotates the rotating body 30, making it easy to detect malfunctions.

[0066] 5(c), if the motor 40 is a hydraulic motor, the construction machine 10 may further include a differential pressure sensor 60c that measures the differential pressure of a valve for controlling the motor 40, and an opening amount sensor 60d that measures the opening amount of the valve. In this case, the estimated information may include information measured by the differential pressure sensor 60c and information measured by the opening amount sensor 60d, and the second acquisition unit 72 may acquire estimated information including this information. The differential pressure sensor 60c and the opening amount sensor 60d are originally used for controlling the operation of the motor 40, but here they are also used for fault detection by the fault detection device 70.

[0067] The estimation unit 73 may estimate the turning angle based on information measured by the differential pressure sensor 60c and information measured by the opening amount sensor 60d. Here, the estimation unit 73 estimates the rotation speed of the motor 40 from the differential pressure measured by the differential pressure sensor 60c and the opening amount measured by the opening amount sensor 60d, and estimates the turning angle by solving a differential equation including the estimated rotation speed of the motor 40 using state estimation theory with a Kalman filter. Note that, while the rotation angle is typically estimated by integrating the rotation speed of the motor 40, this method may result in accumulated errors. Therefore, here, instead of the usual integration method, the estimation unit 73 uses state estimation theory with a Kalman filter, as described above, to estimate the turning angle by solving a differential equation including the estimated rotation speed of the motor 40.

[0068] For example, if the differential pressure measured by the differential pressure sensor 60c is Pdiff, the opening amount measured by the opening amount sensor 60d is Δ, the conversion constant is K, and the rotation speed of the rotating body 30 is R2, the estimation unit 73 estimates the rotation speed of the rotating body 30 by R2 = K × Pdiff ÷ Δ.

[0069] Furthermore, if the estimated rotation angle of the rotating unit 30 is θ2, the time derivative of θ2 is θ2dot, the rotation angle of the rotating unit 30 measured by the angle sensor 50 is y, and the estimated gain is L (L>0), the estimation unit 73 estimates the rotation angle of the rotating unit 30 by solving the differential equation θ2dot=R2-L×(θ2-y) to find θ2.

[0070] The calculation unit 74 calculates the difference using θ2-y, and the determination unit 75 determines whether or not the difference is equal to or greater than a predetermined value for a predetermined period of time.

[0071] Thus, here, the estimated information includes information measured by a differential pressure sensor 60c that measures the differential pressure of a valve for controlling the motor 40 that rotates the rotating body 30, and information measured by an opening amount sensor 60d that measures the opening amount of the valve.

[0072] This makes it easy to estimate the rotation angle of the rotating body 30 based on information measured by the differential pressure sensor 60c, which measures the differential pressure of the valve for controlling the motor 40 that rotates the rotating body 30, and information measured by the opening amount sensor 60d, which measures the opening amount of the valve, so that malfunctions can be easily detected.

[0073] In the above-described embodiment, the first acquisition unit 71 acquires the measurement value of the swing angle of the swing unit 30 of the construction machine 10, but the present invention is not limited to this. The first acquisition unit may acquire the measurement value of the swing angle of a swing unit other than a construction machine.

[0074] In the above-described embodiment, a case has been described in which one rotation angle is estimated and the difference is calculated by comparing the one rotation angle with the measured value of the rotation angle, but this is not limited to this. Two or more rotation angles may be estimated from two or more types of estimated information, and the difference may be calculated by comparing the two or more rotation angles with the measured value of the rotation angle. For example, the difference may be calculated by comparing a rotation angle estimated based on information measured by the encoder 60, a rotation angle estimated based on information measured by the current sensor 60a, and the measured value of the rotation angle.

[0075] Although the embodiments of the present invention have been described above with reference to the accompanying drawings, the technical scope of the present invention is not limited to the above-described embodiments. It is clear that those skilled in the art can conceive of various modifications and alterations within the scope of the technical ideas described in the claims, and it is understood that these modifications and alterations also fall within the technical scope of the present invention. [Explanation of symbols]

[0076] 10: Construction machinery 20: Running body 30: Rotating body 31: Rotating section 32: Cab 33: Shovel Club 34: Turning gear 35: Rotating axis 40: Motor 41: Gear 50: Angle sensor 60: Encoder 60a: Current sensor 60b: Flow sensor 60c: Differential pressure sensor 60d: Opening amount sensor 70:Fault detection device 71:First acquisition part 72:Second acquisition part 73:Estimation part 74: Calculation section 75: Judgment section A: Swivel axis

Claims

1. a first acquisition unit that acquires a measurement value measured by an angle sensor that measures a rotation angle of the rotating body; a second acquisition unit that acquires estimation information for estimating the turning angle; an estimation unit that estimates the turning angle based on the estimation information acquired by the second acquisition unit; a calculation unit that calculates a difference between the measurement value acquired by the first acquisition unit and the estimated value of the turning angle estimated by the estimation unit; a determination unit that determines that a failure has occurred when the difference calculated by the calculation unit is equal to or greater than a predetermined value for a predetermined period of time.

2. 2. The failure detection device according to claim 1, wherein the estimated information includes information measured by an encoder provided for a motor that rotates the rotating body.

3. 2. The failure detection device according to claim 1, wherein the estimated information includes information measured by a current sensor that measures a current supplied to an electric motor that rotates the rotating body.

4. 2. The failure detection device according to claim 1, wherein the estimated information includes information measured by a flow rate sensor that measures the flow rate of hydraulic oil supplied to a hydraulic motor that rotates the rotating body.

5. 2. The failure detection device according to claim 1, wherein the estimated information includes information measured by a differential pressure sensor that measures a differential pressure of a valve for controlling a hydraulic motor that rotates the rotating body, and information measured by an opening amount sensor that measures an opening amount of the valve.

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