SERVO SYSTEM AND METHOD FOR CONTROLLING SERVO SYSTEM

Abstract

To enable continuous operation of a servomotor using an estimated measurement value obtained from a visual sensor even when an encoder is abnormal.SOLUTION: A servo system comprising a servomotor equipped with an encoder and a servo amplifier that controls the servomotor using a measured value of the encoder, is provided with a visual sensor for capturing an image of a controlled object driven by a servomotor and an ambient environment detector for detecting the ambient environment. The servo amplifier calculates a first estimated measurement value corresponding to the measurement value of the encoder based on an input image, determines soundness of data of the first estimated measurement value if the encoder is normal and stores the ambient environment data as guarantee-able environment data if the soundness is present. Then, if the encoder is abnormal, the servo amplifier compares the input ambient environment data with already stored guarantee-able environment data, and if applicable data is present, the servo amplifier controls the servo motor using the first estimated measurement value.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a servo system and a control method for a servo system. [Background technology]

[0002] Servo systems are widely used in various industrial fields. In general, a servo system has a servo motor equipped with an encoder that outputs (measures) the rotation speed and position of the motor, and a servo amplifier that controls the servo motor by feeding back the encoder output and supplying the servo motor with power that eliminates the difference between the encoder output and the operation command.

[0003] In such a servo system, a technique has been known in the past to detect (determine) whether the output of an encoder is normal, and to stop a servo motor if the output of the encoder is abnormal. For example, Japanese Patent Laid-Open Publication No. 2010-284781 (Patent Document 1) discloses a technique in which, in a servo system for driving a robot, a visual sensor that captures an image of a target within its field of view is attached to an arm, a first measurement value obtained by image processing the image captured by the visual sensor is compared with a second measurement value obtained from the encoder, and if the difference between the comparison exceeds a set threshold, it is determined that the encoder is abnormal and the servo motor is stopped. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2010-284781 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the conventional servo systems described above (for example, Patent Document 1 above), an abnormality in the encoder is detected, and the servo motor is stopped if an abnormality in the encoder is detected, thereby preventing the servo motor from running out of control due to an abnormality in the encoder, and realizing a highly safe servo system.

[0006] However, in conventional servo systems, if an encoder malfunctions, the servo motor is stopped without exception, so the servo system cannot continue to operate when an encoder malfunctions. For this reason, in servo systems used on production lines, etc., there remains the issue of reduced operating rate and reduced productivity.

[0007] Therefore, an object of the present invention is to provide a servo system and a control method for a servo system in which, even if an encoder in the servo system is abnormal, if it is determined that the conditions for ensuring safety are met, the servo motor is controlled using an estimated measurement value obtained from a visual sensor, thereby enabling the servo system to continue operating. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention provides, as an example, a servo system including a servo motor equipped with an encoder and a servo amplifier that controls the servo motor using a measurement value of the encoder, the servo system including a visual sensor that captures an image of a control object driven by the servo motor, and an ambient environment detection unit that detects the ambient environment of the servo system, the servo amplifier inputs the image and the ambient environment, calculates a first estimated measurement value corresponding to the measurement value based on the image, and during a period when the encoder is normal, judges the soundness of the data based on whether or not the difference between the measurement value and the first estimated measurement value is within a predetermined threshold, and if the data is sound, stores the ambient environment data as guaranteeable environmental data, and if it is determined that the encoder is abnormal, compares the input ambient environment data with the stored guaranteeable environmental data, and if corresponding guaranteeable environmental data exists, controls the servo motor using the first estimated measurement value.

[0009] In order to solve the above-mentioned problems, another example of the present invention is a control method for a servo system including a servo motor having an encoder and a servo amplifier that controls the servo motor using a measurement value of the encoder, the control method comprising: taking in an image of a control target driven by the servo motor using a visual sensor and taking in ambient environment data of the servo system using an ambient environment detection unit; calculating a first estimated measurement value corresponding to the measurement value based on the image; This is a control method for a servo system, in which during a period in which the encoder is normal, the soundness of the data is determined based on whether the difference between the measurement value and the first estimated measurement value is within a predetermined threshold, and if the data is sound, the surrounding environment data is stored as guaranteeable environment data, and if it is determined that the encoder is abnormal, the input surrounding environment data is compared with the guaranteeable environment data, and if corresponding guaranteeable environment data is present, the servo motor is controlled using the first estimated measurement value. Effect of the Invention

[0010] According to the present invention, in a servo system, the soundness of the estimated measurement value obtained from the visual sensor while the encoder is normal is judged, and the surrounding environment data when the soundness is found is stored as guaranteeable environment data. In the event of an encoder abnormality, if the input surrounding environment data corresponds to the stored guaranteeable environment data, the servo motor is controlled based on the estimated measurement value estimated and calculated from the image from the visual sensor, thereby allowing the servo system to continue operating. [Brief description of the drawings]

[0011] [Figure 1] 1 is a diagram illustrating a configuration of a servo system according to a first embodiment of the present invention. [Diagram 2] FIG. 4 is a diagram showing an example of stored surrounding environment data. [Diagram 3] FIG. 11 is a diagram showing an operation flow of the arithmetic processing unit when the encoder is normal. [Figure 4] FIG. 11 is a diagram showing an operation flow of the arithmetic processing unit when the encoder is abnormal. [Diagram 5] FIG. 11 is a diagram illustrating a configuration of a servo system in a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, the embodiments (examples) of the present invention will be described in detail with reference to the drawings. Here, the present invention is not to be interpreted as being limited to the contents of the examples described below. It will be easily understood by those skilled in the art that the configuration of the present invention can be changed without departing from the technical idea or purpose of the present invention.

[0013] In addition, in the configurations of the embodiments described below, the same symbols are used in different drawings for the same devices or parts having similar functions, and duplicated descriptions may be omitted. In addition, the position, size, shape, range, etc. of each component shown in the drawings do not represent the actual position, size, shape, range, etc., in order to facilitate understanding of the invention. Therefore, the present invention is not limited to the position, size, shape, range, etc. of the component devices disclosed in the drawings.

[0014] Example 1 Next, a first embodiment of the present invention will be described with reference to Figs. 1 to 4. Fig. 1 is a diagram showing a configuration of a servo system in the first embodiment. Fig. 2 is a diagram showing an example of surrounding environment data stored in a storage unit. Figs. 3 and 4 are diagrams showing an operation flow of the servo system in the first embodiment.

[0015] First, the overall configuration of a servo system according to the embodiment will be described with reference to Fig. 1. In Fig. 1, a servo system 1 includes a servo motor 20 equipped with an encoder 21, and a servo amplifier 10 that controls the servo motor 20. In the system according to the first embodiment, the servo amplifier 10 and a host controller 50 are connected to be able to communicate with each other.

[0016] Moreover, in this first embodiment, a visual sensor 30 is installed so as to be able to capture images of the time variation (movement state) of a control object driven and controlled by a servo motor, and an ambient environment detection unit 40 is provided to detect the ambient environment of the servo system. The visual sensor 30 is installed so as to be able to capture images for estimating the measurement values ​​by the encoder. For example, the visual sensor is installed at a location (position, attitude) where the movement of the control object driven by the servo motor can be captured in an image. The ambient environment detection unit 40 detects physical quantity data that may affect the image of the visual sensor.

[0017] Here, the "ambient environment" refers to the state around the servo system, particularly the environment that affects the image captured by the visual sensor. The "ambient environment data" refers to data indicating physical quantities in the ambient environment. Specific examples of ambient environment data include the light intensity (illuminance) that affects the image content captured by the visual sensor, the amount of dust (amount of dust) at the location where the visual sensor is installed, and the degree of dirt on the lens of the visual sensor. The "imaging conditions" of the visual sensor specifically refer to the attitude of the camera lens, the focal length, the zoom amount, and the like. In the embodiment, the ambient environment data is measured (detected) when the image of the servo system is captured by the visual sensor, but it is not necessary to measure all the physical data of the light intensity, the amount of dust, and the degree of dirt on the lens, and any one of these physical quantities may be selected and measured. Similarly, the imaging conditions may be obtained by determining all of the attitude, focal length, and zoom amount of the camera lens, but basically any one of them may be selected.

[0018] The servo amplifier 10 in this embodiment has a motor control unit 11 that feeds back the output of an encoder 21 (measured values ​​of the motor speed and position) and controls the power supplied to the servo motor 20, an arithmetic processing unit 12, and a storage unit 14. A current sensor 13 is a sensor that detects the current supplied to the motor. A current sensor is usually installed inside the motor control unit 11 and is often used for feedback control of current control, but here it is described as being outside the motor control unit 11.

[0019] When the encoder 21 is normal, the motor control unit 11 feeds back and inputs the speed and position data (hereinafter, measurement value) A0 measured by the encoder 21 via the switching unit 110, calculates the deviation between the measurement value A0 of the encoder 21 and the motor operation command S, and supplies power to the servo motor 20 by the control unit 111 so as to eliminate the deviation, thereby controlling the speed and position of the servo motor 20. Therefore, when the encoder 21 is normal (during the period in which it is determined to be normal), the switching unit 110 is switched to the side that inputs the measurement value A0 of the encoder. When it is determined that the encoder 21 is abnormal, the switching unit 110 switches to a side that allows the estimated measurement value (hereinafter, first estimated measurement value) A1 obtained from the image of the visual sensor to be supplied to the motor control unit 11 in response to a switching signal C from the calculation processing unit 12.

[0020] The calculation processing unit 12 gives an operation command S to the motor control unit 11, and also receives the measurement value A0 of the encoder, the image G captured by the visual sensor, the surrounding environment KD, and the current I to be supplied to the servo motor 20.

[0021] First, in this servo system, while the servo motor 20 is in operation, it is determined at a predetermined timing whether the encoder 21 is normal or not. Also, a first estimated measurement value A1 corresponding to the measurement value A0 is calculated based on the input image G. During the period during which the encoder 21 is determined to be normal (period during which the encoder is normal) by the encoder abnormality determination (abnormality detection), it is determined whether the difference between the measurement value A0 and the first estimated measurement value A1 is within a predetermined threshold value, and the soundness of the data is determined.

[0022] Then, when the first estimated measurement value A1 is determined to be healthy, the surrounding environment data KD is stored as "guaranteed environment data" in the storage unit 14. These calculation, judgment, and storage operations are performed at regular time intervals while the encoder 21 is normal.

[0023] When it is determined that the encoder 21 is abnormal, the calculation processing unit 12 compares (collates) the input surrounding environment data KD with the guaranteeable environment data stored in the storage unit 14 during the encoder normal period. As a result, when the input surrounding environment data KD matches the first estimated measurement value A1 among the first estimated measurement values ​​A1, it is determined that the current first estimated measurement value can be used for motor control. In this case, the calculation processing unit 12 supplies the first estimated measurement value A1 to the motor control unit 11 instead of the measurement value A0 of the encoder 21. Specifically, it outputs a switching signal C and the first estimated measurement value A1 to the motor control unit 11. As a result, the motor control unit 11 can switch the switching unit 110 and control the operation of the servo motor 20 using the first estimated measurement value A1. In other words, even when the encoder is abnormal, if the surrounding environment is the same as or equivalent to the surrounding environment in which the soundness judgment was made in the normal state, the operation of the servo motor is continued.

[0024] Furthermore, if the calculation processor 12 determines that the encoder 21 is abnormal and that the input surrounding environment data KD does not correspond to the stored guaranteeable environment data, it determines that the accuracy of the first estimated measurement value is low and cannot be used for motor control, and outputs a motor stop signal ST to the motor control unit 11. In response to this stop signal ST, the motor control unit 11 cuts off the power supply to the motor to stop the servo motor 20.

[0025] In this way, the servo system 1 can continue to operate if it is determined that a certain condition that can ensure safety is satisfied even if the encoder 21 is abnormal. A specific configuration of the arithmetic processing unit 12 and a detailed description of a series of arithmetic processing operations will be described later.

[0026] Next, a more detailed configuration of the arithmetic processing unit 12 will be described. Specifically, the arithmetic processing unit 12 can be realized by a computer or a processor having a calculation function. Here, the arithmetic processing unit 12 is realized by a ROM 121 that stores a program, a RAM that temporarily records various information (data) for arithmetic processing, an image processing unit 123 that performs image processing to estimate a measurement value for an input image, a CPU 124 that executes a series of arithmetic processing based on the program, a setting unit 125 that sets information, and an I / O 126 that controls input and output to perform mutual communication of information with the upper controller 50. Each device in the arithmetic processing unit 12 is connected by a bus 127 that allows mutual communication. The storage unit 14 and the arithmetic processing unit 12 are also connected by a bus that allows mutual communication.

[0027] It is preferable to use a dynamically reconfigurable processor (DRP) capable of processing image data at high speed for the image processing unit 123. A dynamically reconfigurable processor (DRP) is hardware that executes applications while dynamically switching connections between computing units. The DRP itself is well known, and detailed description thereof will be omitted here.

[0028] With the configuration described above, the calculation processing unit 12 stores various information (data) in the memory unit 14, and also imports the information (data) stored in the internal memory and various information stored in the memory unit 14 to perform a series of calculation processes.

[0029] Next, the operation of the embodiment 1 shown in FIG. 1 will be described with reference to FIGS.

[0030] 1, a servo amplifier 10 receives measurement values ​​(speed and position of the motor) of an encoder 21. The input measurement values ​​are usually input to a motor control unit 11 and are also input to an arithmetic processing unit 12 at the same time.

[0031] Meanwhile, in synchronization with the input of the measured values ​​of the encoder 21, the calculation processing unit 12 inputs the image captured by the visual sensor 30, the surrounding environment detected by the surrounding environment detection unit 40, and the current detected by the current sensor 13. The calculation processing unit 12 also takes in the shooting conditions of the visual sensor 30. The shooting conditions may be configured as part of the surrounding environment detection unit 40. Alternatively, they may be set from the setting unit 125. These pieces of information (data) are temporarily stored in the internal RAM 122, and then stored in the memory unit 14 by the processing operation of the CPU 124.

[0032] First, the calculation processing unit 12 (CPU 124) executes an abnormality judgment (abnormality detection) process to judge whether the encoder 21 is normal or not. This abnormality judgment method itself is well known (see JP 2005-198467 A, JP 5-344775 A, JP 2001-333590 A, JP 2002-350184 A, WO2019 / 031219, etc.). In addition, the method described in the above-mentioned Patent Document 1 may be used. A detailed description of this abnormality judgment will be omitted.

[0033] Next, when the encoder is normal, the calculation processing unit 12 (CPU 124) estimates and calculates physical quantities corresponding to the encoder measurement values ​​(motor speed and position) using image data that has been image-processed by the image processing unit 123 and stored in the RAM 122. This method of estimation and calculation using images is well known, so a description thereof will be omitted here. For example, a method such as that described in Patent Document 1 may be used. Hereinafter, the motor speed and position values ​​calculated based on this image will be referred to as "first estimated measurement value A1" since they are estimated values ​​corresponding to the encoder measurement values. Here, the estimated value based on the image is referred to as the "first estimated measurement value" in order to distinguish it from an estimated value estimated from a current.

[0034] Next, the calculation processing unit 12 (CPU 124) obtains the difference between the first estimated measurement value A1 and the encoder measurement value A0, and judges whether or not this difference exceeds a pre-stored threshold value. If the difference does not exceed the threshold value, it is judged that the first estimated measurement value A0 obtained based on the image G captured by the visual sensor 30 is sound.

[0035] In this embodiment, a "second estimated measurement value A2" which is an estimated value corresponding to the measurement value (motor speed and position) of the encoder 21 is also calculated based on the motor current I. Then, in addition to judging the soundness by comparing the above-mentioned first estimated measurement value A1 with the encoder measurement value A0, a judgment is also made by comparing the difference between the first estimated measurement value A1 and this second estimated measurement value A2 with a threshold value. In other words, the soundness of the first estimated measurement value A1 is judged using not only the encoder measurement value A0 but also the second estimated measurement value A2. This makes the soundness judgment more accurate.

[0036] Then, when the soundness is judged to be "sound", the surrounding environment data KD stored in the RAM 122, the encoder measurement value, the estimated measurement value calculated based on the image, and the like are stored in the storage unit 14 as "guaranteable environment data". When the first estimated measurement value A1 is judged to be "not sound" as a result of the soundness judgment, the surrounding environment data is stored in the storage unit 14 as unguaranteable environment data (unguaranteable environment data). Specifically, for example, information "1" when the data is guaranteable and "0" when the data is unguaranteable is used as the judgment information, and the judgment information is stored together with the surrounding environment data KD. Thereby, it is possible to distinguish whether the surrounding environment data KD is "guaranteable environment data" or "unguaranteable environment data". In this embodiment, when the environmental data is stored, "calibration data" used for adjusting (correcting) the first estimated measurement value and the visual sensor is also stored as a set. The details of this will be described later.

[0037] Next, an example of information (environmental data and calibration data) stored in the storage unit 14 will be described with reference to Fig. 2. Fig. 2 shows an example of information (data) recorded by the storage unit 14, which is stored as a data set for each mode. That is, the measurement value A0 of the encoder, the first estimated measurement value A1 estimated and calculated based on the image of the visual sensor, and the second estimated measurement value A2 estimated and calculated based on the current are stored together with the surrounding environment data KD.

[0038] This environmental data KD also stores information on whether the accuracy can be guaranteed or not. This information is for storing as "guaranteable environmental data" when it is determined that the first estimated measurement value is sound. In other words, this information on whether the accuracy can be guaranteed makes it possible to determine that the stored surrounding environment is "guaranteable environmental data". In this example, the environmental data to be stored are light intensity, dust amount, and lens dirt. Although the actually measured physical data itself may be stored, here, each physical quantity is stored by dividing it into multiple levels. For example, in the case of light intensity, the intensity is divided into five levels from strong to weak, and the corresponding level is stored instead of the actual intensity. By dividing the levels and storing them in this way, it becomes possible to efficiently perform a collation operation when an encoder abnormality occurs.

[0039] In addition to these data, calibration data is also stored in FIG. 2. In the example of FIG. 2, two types of data are stored. The first is "data for correcting estimated values" and the second is "data for adjusting visual sensors." The data for correcting estimated values ​​is specifically the difference between the encoder measurement value A0 and the first estimated measurement value A1 estimated based on the image, and the ratio between them. The data for adjusting visual sensors is the orientation, zoom, and focal length of the visual camera.

[0040] These calibration data are used when performing adjustment (calibration) when it is determined that the encoder 21 is abnormal. Specifically, when the calculation processing unit 12 outputs the first estimated measurement value A1 to the motor control unit 11, the calculation processing unit 12 adjusts the first estimated measurement value A1 using the data for correcting the estimated value and outputs the adjusted first estimated measurement value A1. For example, when the difference between the two measurement values ​​is used, the adjustment is such that the value obtained by subtracting this difference from the raw first estimated measurement value A1 calculated based on the image is output to the motor control unit 11 as the adjusted first estimated measurement value A1. When the ratio is used, the adjustment is such that the calculated raw first estimated measurement value A1 is multiplied by this ratio and output to the motor control unit 11 as the adjusted first estimated measurement value A1. The shooting correction data is used to adjust the attitude, focus, etc. of the visual sensor. In FIG. 1, the dashed line connecting the calculation processing unit 12 to the visual sensor 30 indicates that the visual sensor 30 is adjusted.

[0041] 2, the calibration data may be stored together with the guaranteeable environmental data in the storage unit 14, or may be stored separately from the guaranteeable environmental data in another storage area of ​​the storage unit 14 or in a storage unit other than the storage unit 14. In that case, however, it is necessary to link the guaranteeable environmental data and the calibration data so that they can be associated with each other. Also, while FIG. 2 shows an example in which two types of calibration data are stored, it is also possible to store any one type of data.

[0042] Next, the operation of the servo amplifier 10 in Fig. 1 (basically, the operation of the arithmetic processing unit 12) will be described with reference to Fig. 3 and Fig. 4. Fig. 3 shows the operation flow when the encoder 21 is normal, and Fig. 4 shows the operation flow when the encoder 21 is abnormal.

[0043] First, the operation of the arithmetic processing unit 12 when the encoder 21 is normal will be described with reference to FIG. In step S101 of Fig. 3, a diagnosis is made as to whether the encoder is normal. In S102, the result of this diagnosis is used to determine whether the encoder 21 is normal or abnormal, and if the encoder 21 is normal, the process proceeds to step S103. If it is determined that the encoder 21 is abnormal, the process proceeds to step S200, where a processing operation for when the encoder is abnormal is executed. The operation contents when it is determined that the encoder is abnormal will be described later with reference to Fig. 4.

[0044] 3, the data measurement value, the image, the current, and the surrounding environment data are input and stored at each predetermined timing. In addition, in step S104, the first estimated measurement value A1 is calculated from the image captured by the visual sensor 30, and the second estimated measurement value is calculated from the current.

[0045] Next, in step S105, the soundness of the data of the first estimated measurement value A1 is judged. The first estimated measurement value is compared with the encoder measurement value, and if the difference is within a threshold, it is judged to be sound. The first estimated measurement value is also compared with the second estimated measurement value to judge the soundness of the first estimated measurement value A1. If either of them exceeds the threshold, it is judged that the first estimated measurement value A1 is not sound.

[0046] In the next step S106, if it is determined that the data of the first estimated measurement value A1 is sound, the process proceeds to step S107. If it is determined that the data is not sound, the process proceeds to step S109.

[0047] In step S107, the surrounding environment when it is determined that the soundness is present is stored in the memory unit 14 as guaranteeable environment data together with the measured value A0, the first estimated measured value A1, and the second estimated measured value A2 at that time. At that time, calibration data is also stored as shown in step S108. The contents of this are as shown in FIG. 2. In step S109, the surrounding environment when it is determined that the soundness is not present is stored as non-guaranteable environment data together with the measured value A0, the first estimated measured value A1, and the second estimated measured value A2 at that time. Note that when it is determined that the soundness is not present, the calibration data may or may not be stored.

[0048] Next, in step S110, it is determined whether or not the servo motor 20 is currently being driven. If the servo motor 20 is currently being driven, the process returns to step S101, and the operations from step S101 to step S110 are continuously executed.

[0049] In this way, when the encoder 21 is normal, the calculation processing unit 12 stores information such as that shown in Fig. 2 in the storage unit 14 at predetermined intervals. It is convenient not to store new information when the contents to be stored next are the same as those already stored. In this way, the number of sets of guaranteeable environmental data stored in the storage unit 14 does not increase more than necessary, and comparison and collation of the environmental data with the stored guaranteeable environmental data can be efficiently performed when the encoder 21 is abnormal.

[0050] Next, the operation when the encoder 21 is abnormal (NO in step S102 in FIG. 3) will be described with reference to FIG.

[0051] 4, in step S201, the input of data continues as in the case where the encoder is normal. At least the input of the image G and the surrounding environment data KD continues.

[0052] In step S202, a first estimated measurement value is calculated based on image G. In addition, in step S203, the surrounding environment data input after the encoder abnormality is determined is compared with the "guaranteed environment data" stored when the encoder was normal. If the surrounding environment at that time corresponds to (applies to) the guaranteed environment data, the first estimated measurement value at that time satisfies the condition that it is an estimated value in an environment where accuracy can be guaranteed.

[0053] In step S205, the comparison result is checked to determine whether the input surrounding environment corresponds to (is included in) the guaranteeable environment data, and if there is a corresponding data, the process proceeds to step S205. If the comparison result shows that the input surrounding environment does not correspond to (is not included in) the stored guaranteeable environment data, the process proceeds to step S208.

[0054] In step S205, the first estimated measurement value calculated in step S202 is calibrated using the calibration data (estimated value correction data shown in FIG. 2). That is, the calculated first estimated measurement value A1 is corrected (adjusted).

[0055] Then, in step S206, the corrected first estimated measurement value A1 is output to the motor control unit 11 together with the switching signal C. As a result, the motor control unit 11 stops the measurement value A0 (abnormal state) of the encoder 21 that has been fed back and input, and switches to input the first estimated measurement value A1 output by the arithmetic processing unit 12. That is, the switching unit 110 in FIG. 1 is switched by the switching signal C, and the first estimated measurement value A1 is input to the motor control unit 11. This switching allows the motor control unit 11 to control the servo motor 20 using the first estimated measurement value A1 supplied from the arithmetic processing unit 12. That is, the operation of the servo system 1 can be continued.

[0056] In the next step S207, it is determined whether or not the servo motor 20 is in operation. If the servo motor 20 is in operation, the process returns to step S201 and the above-mentioned operations are repeated.

[0057] On the other hand, in step S204, if the input ambient environment data does not correspond to the guaranteeable environment data, the operation of step S208 is executed. That is, it is determined that the accuracy (reliability) of the calculated first estimated measurement value is low, and a stop command ST for the servo motor 20 is output to the motor control unit 11. In response to this stop command, the motor control unit 11 cuts off the power supplied to drive the servo motor 20, and stops the servo motor 20.

[0058] Thus, according to the servo system of the first embodiment, the servo amplifier 10 inputs an image and the surrounding environment from the visual sensor, calculates a first estimated measurement value corresponding to the encoder measurement value (speed and position) based on the image, and when the encoder is normal, judges the soundness of the data based on whether the difference between the encoder measurement value and the first estimated measurement value is within a predetermined threshold value, and when the data is sound, stores the inputted surrounding environment data as the guaranteeable environment data, and when the encoder is determined to be abnormal, if the inputted surrounding environment data corresponds to the guaranteeable environment data stored when the encoder is normal, it can switch from the encoder measurement value to the first estimated measurement value and continue to control the servo motor. And when the inputted surrounding environment data does not correspond to the guaranteeable environment data stored when the encoder is normal, it stops the servo motor.

[0059] In this embodiment, when storing the guaranteed environment data, calibration data for adjusting the value of the first estimated measurement value is stored, the first estimated measurement value is corrected by this calibration data, and the servo motor control is continued by the corrected first estimated measurement value, so that it is possible to continue operation with higher safety. Also, since data for performing calibration of the attitude of the visual sensor, etc. is stored, it is possible to stabilize the imaging conditions of the visual sensor itself.

[0060] Example 2 Next, a servo system according to a second embodiment of the present invention will be described with reference to the drawings. Fig. 5 is a diagram showing the configuration of the servo system according to the second embodiment.

[0061] In the servo system of the first embodiment (FIG. 1), the arithmetic processing unit 12 and the storage unit 14 are provided in the servo amplifier 10. In contrast, the servo system 1 of the second embodiment is different in that the arithmetic processing unit 12 and the storage unit 14 are provided in the upper controller 50. In other respects, the first embodiment and the second embodiment perform the same control.

[0062] That is, the contents of this second embodiment are almost the same as those described in the first embodiment. Therefore, the duplicated description of the contents already described will be omitted here. Specifically, the arithmetic processing unit 12 provided in the upper controller 50 is functionally equivalent to the arithmetic processing unit 12 in the servo amplifier 10 of the first embodiment. The contents stored in the memory unit 14 are also the same as those shown in FIG. 2. Furthermore, the operation flow in the arithmetic processing unit 12 is also the same as those shown in FIG. 3 and FIG. 4. Therefore, the duplicated description of those matters will be omitted. In the second embodiment, the servo amplifier 10 and the upper controller are also connected to be able to communicate with each other. The following will mainly explain the differences between the second embodiment and the first embodiment.

[0063] 5, the surrounding environment data KD, the image G captured by the visual sensor 30, the current I, and the measurement values ​​of the encoder 21 (speed and position of the motor) are taken in (inputted) to a calculation processing unit 12 provided in a host controller 50. Using these data, the calculation processing unit 12 calculates a first estimated measurement value corresponding to the measurement values ​​(speed and position) of the encoder 21 based on the image G, and if the encoder 21 is normal, judges the soundness of the data based on whether or not the difference between the measurement value of the encoder and the first estimated measurement value is within a predetermined threshold value.

[0064] If the data is sound, the surrounding environment data KD is stored as the guaranteeable environment data, and if it is determined that the encoder 21 is abnormal, and the input surrounding environment data corresponds to the guaranteeable environment data stored when the encoder was normal, the motor control unit 11 in the servo amplifier 10 is controlled to switch from the encoder measurement value to the first estimated measurement value A1. That is, the calculation processing unit 12 outputs a switching signal C and the first estimated measurement value A1 to the motor control unit 11. This allows the motor control unit 11 to continue operating the servo motor using the first estimated measurement value A1.

[0065] If the input surrounding environment data KD does not correspond to the guaranteeable environment data stored when the encoder is normal, the calculation processing unit 12 outputs a stop command ST to the motor control unit 11. When the motor control unit 11 receives this stop command ST, it executes control to stop the servo motor. Note that the adjustment of the first estimated measurement value using the calibration data and the attitude control of the visual sensor have already been explained, so they will not be explained here.

[0066] According to the second embodiment of the present invention, the same effects as those of the above-mentioned first embodiment can be obtained. Furthermore, in the second embodiment, when there are a plurality of servo systems each composed of a servo motor and a servo amplifier, it is not necessary to provide a calculation processing unit for each servo system, so that the overall configuration is simplified. [Explanation of symbols]

[0067] 1 ... servo system, 10 ... servo amplifier, 11 ... motor control unit, 12 ... arithmetic processing unit, 13 ... current sensor, 14 ... storage unit, 20 ... servo motor, 21 ... encoder, 50 ... upper controller, 110: switching unit, 111: control unit, 121: ROM, 122: RAM, 123: image processing unit, 124: CPU, 125: setting unit, 126: I / O

Claims

1. A servo system including a servo motor having an encoder and a servo amplifier that controls the servo motor by feeding back a measurement value of the encoder, a visual sensor for capturing an image of a control target driven by the servo motor; and a surrounding environment detection unit for detecting environmental data affecting the image captured by the visual sensor as surrounding environment data of the servo system, The servo amplifier inputs the image and the surrounding environment data, calculates a first estimated measurement value corresponding to the measurement value based on the image, and during a period in which the encoder is normal, judges the integrity of the data based on whether the difference between the measurement value and the first estimated measurement value is within a predetermined threshold value.If the data is intact, the surrounding environment data is stored as guaranteeable environmental data.If the encoder is determined to be abnormal, the inputted surrounding environment data is compared with the stored guaranteeable environmental data, and if corresponding guaranteeable environmental data is present, the servo system controls the servo motor using the first estimated measurement value.

2. 2. The servo system according to claim 1, The servo amplifier records the difference or ratio between the first estimated measurement value and the measurement value together with the guaranteed environmental data when recording the guaranteed environmental data, and when driving and controlling the servo motor using the first estimated measurement value, adjusts the first estimated measurement value using the difference or ratio.

3. 2. The servo system according to claim 1, The servo amplifier records the shooting conditions of the visual sensor together with the guaranteed environment data when recording the guaranteed environment data, and adjusts the visual sensor based on the shooting conditions when controlling the servo motor with the first estimated measurement value.

4. 2. The servo system according to claim 1, a current sensor for detecting a current supplied to the servo motor; The servo amplifier calculates a second estimated measurement value corresponding to the measurement value based on the current, and when determining the soundness, compares the measurement value, the first estimated measurement value, and the second estimated measurement value with each other, and determines that the system is sound if the measured values ​​are within the threshold value.

5. 2. The servo system according to claim 1, said servo amplifier is characterized in that, when it is determined that said encoder is abnormal, said servo amplifier compares said input surrounding environment data with said stored guaranteeable environment data, and when no corresponding guaranteeable environment data exists, said servo amplifier stops said servo motor.

6. 2. The servo system according to claim 1, The servo amplifier includes a motor control unit that controls a motor using a measurement value of the encoder when the encoder is normal, a calculation processing unit that controls the drive of the motor control unit, and a storage unit; The calculation processing unit takes in the image and the surrounding environment data, calculates a first estimated measurement value corresponding to the measurement value based on the image, and, if the encoder is normal, judges the integrity of the data based on whether the difference between the measurement value and the first estimated measurement value is within a predetermined threshold, and if the data is healthy, stores the surrounding environment data in the memory unit as guaranteeable environmental data, and if it is determined that the encoder is abnormal and the inputted surrounding environment data corresponds to the guaranteeable environmental data stored in the memory unit, supplies the first estimated measurement value to the motor control unit, and the motor control unit controls the motor using the supplied first estimated measurement value.

7. 7. The servo system according to claim 6, A servo system comprising a host controller connected to said servo amplifier so as to be capable of communicating with each other, said processing unit and said storage unit being built into said host controller.

8. 2. The servo system according to claim 1, The servo system according to claim 1, wherein the servo amplifier is equipped with a dynamic reconfiguration processor, and when the first estimated measurement value is calculated based on the image, image processing is performed by the dynamic reconfiguration processor.

9. A control method for a servo system including a servo motor having an encoder and a servo amplifier that controls the servo motor by feeding back a measurement value of the encoder, comprising the steps of: using a visual sensor to capture an image of a control target driven by the servo motor, and using a surrounding environment detection unit to capture data of an environment that affects the image captured by the visual sensor as surrounding environment data of the servo system, and calculating a first estimated measurement value corresponding to the measurement value based on the image; During a period in which the encoder is normal, the soundness of the data is determined based on whether or not a difference between the measurement value and the first estimated measurement value is within a predetermined threshold value, and if the data is sound, the surrounding environment data is stored as assurable environment data; A method for controlling a servo system, comprising: when it is determined that the encoder is abnormal, comparing the input surrounding environment data with the guaranteeable environment data; and when corresponding guaranteeable environment data exists, controlling the servo motor using the first estimated measurement value.

10. 10. A method for controlling a servo system according to claim 9, further comprising the steps of: A control method for a servo system, characterized in that when recording the guaranteed environmental data, the servo amplifier records the difference or ratio between the first estimated measured value and the measured value together with the guaranteed environmental data, and when driving and controlling the servo motor using the first estimated measured value, the servo amplifier adjusts the first estimated measured value using the difference or ratio.

11. 10. A method for controlling a servo system according to claim 9, further comprising the steps of: A method for controlling a servo system, comprising the steps of: when recording the guaranteeable environment data, recording the shooting conditions of the visual sensor together with the guaranteeable environment data; and when controlling the servo motor with the first estimated measurement value, adjusting the visual sensor based on the shooting conditions.

12. 10. A method for controlling a servo system according to claim 9, further comprising the steps of: Calculating a second estimated measurement value based on a current supplied to the servo motor; A control method for a servo system, characterized in that, when judging the health of a servo system, the health of the servo system is judged to be present if the mutual deviation between the second estimated measurement value based on the current, the first estimated measurement value based on the visual sensor, and the measurement value by the encoder is within the threshold value.

13. 10. A method for controlling a servo system according to claim 9, further comprising the steps of: a servo system control method comprising: determining that the encoder is abnormal; comparing the input surrounding environment data with the stored guaranteeable environment data; and stopping the servo motor if the corresponding guaranteeable environment data is not present.

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