JP2009217439A - Control apparatus and its operation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control apparatus extending a normal operation period of a nonvolatile memory until failure occurs by writing frequency restriction by restricting writing into the nonvolatile memory, and to provide its operation method. <P>SOLUTION: This control apparatus, for outputting an operation amount according to a control parameter to a control target such that a measurement value is brought close to a set value, has: an arithmetic processing part 11 calculating a characteristic amount of a control response; a RAM 13 holding the characteristic amount; and a rewritable EEPROM written with the characteristic amount held in the RAM 13. When writing data of the characteristic amount newly held in the RAM 13 into the EEPROM 12, the control apparatus decides whether to perform writing to the EEPROM 12 from the RAM 13 or not by use of data of the past characteristic amount held in the EEPROM 12 and the data of the new characteristic amount held in the RAM 13. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a control device and an operation method thereof, and more particularly to a control device having a nonvolatile memory and an operation method thereof.

  A controller is used to control the temperature of a heat treatment furnace or the like. In the controller, numerical parameters to be held prior to control, such as parameters that depend on the type and operating conditions of sensors and actuators connected for control, parameters used for control calculations such as control set values and adjustment factors, etc. Exists. For example, in a controller that performs PID control, it is necessary to set a large number of parameters such as PID parameters. The controller uses these parameter settings to control the temperature. That is, the controller performs PID control based on the measurement value of the temperature sensor.

  The controller outputs an operation amount based on the set value set to the target temperature and the measured temperature using the PID parameter. Thereby, measurement temperature can be brought close to target temperature. Here, in the control by the controller, it is necessary to set a control parameter such as a PID parameter. For example, a method of optimizing PID by auto tuning is disclosed (Patent Document 1).

  Such PID parameters are written and held in the memory. For example, an EEPROM (Electrically Erasable Programmable Read Only Memory) is generally adopted as a memory medium for storing parameters. In the EEPROM, the number of times of writing is limited (Patent Document 2).

JP-A-4-84201 JP-A-5-73435

  Control result information (feature data in the control response such as set value arrival time and overshoot amount) is effective as a control result for the actual control target when grasping the control failure state and adjusting control parameters such as PID. Information. However, it is often difficult to predict the occurrence of a defect in advance prior to control. For this reason, it is conceivable that a feature amount is calculated inside the controller while performing a series of control operations such as temperature increase and decrease, and stored in the EEPROM together with parameters related to control conditions such as control parameters. Here, each time a series of control operations (temperature increase, temperature decrease, etc.) are performed on the EEPROM, the control result information is written.

  On the other hand, as described above, the EEPROM has a limit on the number of times of writing. If writing is performed beyond this, there is a high possibility that an EEPROM malfunction or failure will occur, and this causes a controller failure that prevents the control operation. In this case, the EEPROM needs to be replaced.

  Japanese Patent Application Laid-Open No. 2004-228561 has a counter unit that accumulates and counts the number of times of writing to the EEPROM. When the count value reaches the reference abnormal value within a predetermined time, an alarm is issued. As a result, it is possible to confirm whether unintended writing due to a setting mistake or the like is not frequently performed, and the user can deal with it. However, in a controller having a function of calculating and holding a feature value for each control response, the operation of writing the calculated feature value data to the EEPROM is not an unintended operation due to a user setting error or the like. The writing of feature amount data to the EEPROM is a normal operation used by the user for the purpose of grasping the control failure state and adjusting control parameters such as PID. In other words, when the controller has a function of calculating and holding a feature value for each control response, the number of times of writing feature value data to the EEPROM increases within a normal operation range.

  If the EEPROM write count limit is exceeded, the EEPROM will fail. This necessitates replacement and repair of the memory. Therefore, there is a problem that the period during which the controller can operate normally is shortened. Note that the above problem occurs not only in the controller but also in a control device having a rewritable nonvolatile memory.

  The present invention was made in order to solve such problems, a control device that limits writing to the nonvolatile memory and extends the normal operation period of the nonvolatile memory until failure occurs due to the limitation on the number of times of writing, And an operation method thereof.

  A control device according to a first aspect of the present invention is a control device that outputs an operation amount corresponding to a control parameter to a control target so that a measurement value approaches a set value, and a control response based on the measurement value An arithmetic processing unit that calculates the feature amount of the data, a RAM area that stores the feature amount data calculated by the arithmetic processing unit, and a rewritable data that stores the feature amount data stored in the RAM region Non-volatile memory, and when writing the feature value data newly held in the RAM area to the non-volatile memory, the past feature value data held in the non-volatile memory and the RAM area Is used to determine whether or not to write data from the RAM area to the nonvolatile memory. Thereby, the number of times of writing to the nonvolatile memory can be suppressed, and the normal operation period until failure occurs due to the limitation on the number of times of writing to the nonvolatile memory can be extended.

  A control device according to a second aspect of the present invention is the control device described above, wherein a difference value between the past feature amount data and the new feature amount data is calculated for each feature amount, and Whether to write from the RAM area to the nonvolatile memory is determined according to the difference value. Thereby, it is possible to determine the similarity between the control response corresponding to the past feature amount data and the control response corresponding to the new feature amount data by a simple process.

  A control device according to a third aspect of the present invention is the control device described above, and calculates a value of an evaluation function using the past feature amount data and the new feature amount data, and the evaluation function It is determined whether or not to write from the RAM area to the nonvolatile memory according to the value of. Thereby, it can determine appropriately.

  A control device according to a fourth aspect of the present invention is the control device described above, wherein when a value according to a difference between the past feature amount and the new feature amount exceeds a threshold value, The data is written from the RAM area to the non-volatile memory. As a result, the similarity between the control response corresponding to the past feature amount data and the control response corresponding to the new feature amount data exceeds the threshold range when writing to the nonvolatile memory. By limiting the number of cases, the number of times of writing can be limited.

  A control device according to a fifth aspect of the present invention is the control device described above, wherein the threshold value changes according to a value stored in the nonvolatile memory. . Thereby, the threshold value corresponding to the feature to be controlled can be set, and the feature amount data determined to be effective for the user can be held while limiting the number of times of writing to the nonvolatile memory.

  The operation method of the control device according to the sixth aspect of the present invention includes a rewritable nonvolatile memory, and a control for outputting an operation amount corresponding to a control parameter to a control target so that a measured value approaches a set value. A method of operating a device, the step of calculating a feature amount of a control response, the step of holding the feature amount in a RAM area, and the data of the feature amount newly held in the RAM area in the nonvolatile memory Whether to write data from the RAM area to the non-volatile memory using the past characteristic value data held in the non-volatile memory and the new feature value data held in the RAM area. A step of determining whether or not. Thereby, the number of times of writing to the nonvolatile memory can be suppressed. As a result, the normal operation period due to the limitation on the number of writing times of the nonvolatile memory can be extended.

  The operation method of the control device according to the seventh aspect of the present invention is the operation method described above, wherein a difference value between the past feature amount data and the new feature amount data is calculated for each feature amount. Then, it is determined whether or not to write from the RAM area to the nonvolatile memory in accordance with the difference value. Thereby, it is possible to determine the similarity between the control response corresponding to the past feature quantity and the control response corresponding to the new feature quantity by simple processing.

  The operation method of the control device according to the eighth aspect of the present invention is the operation method described above, and calculates a value of an evaluation function using the past feature amount data and the new feature amount data, In accordance with the value of the evaluation function, it is determined whether to write from the RAM area to the nonvolatile memory in accordance with the value of the evaluation function using the plurality of feature quantities. Thereby, it can determine appropriately.

  The operation method of the control device according to the ninth aspect of the present invention is the operation method described above, wherein a value corresponding to a difference between the past feature amount data and the new feature amount data is a threshold value. In the case where the threshold is exceeded, data is written from the RAM area to the nonvolatile memory. Accordingly, it is possible to limit the number of times of writing by writing to the nonvolatile memory only when the similarity between the feature quantities exceeds the threshold range.

  The operation method of the control device according to the tenth aspect of the present invention is the operation method described above, wherein the threshold value changes according to a value stored in the nonvolatile memory. Is. Thereby, the threshold value corresponding to the feature to be controlled can be set, and the feature amount data determined to be effective for the user can be held while limiting the number of times of writing to the nonvolatile memory.

  ADVANTAGE OF THE INVENTION According to this invention, the control apparatus which restrict | limits the write-in to a non-volatile memory, and extends | stretches the normal operation period of a non-volatile memory until it fails by a write frequency limit, and its operating method can be provided.

  The inventor paid attention to the following points in order to extend the normal operation period of the EEPROM until failure due to the limitation of the number of writing when the control result information is stored in the EEPROM.

A typical case where the above control result information is required is when the controller is installed on a specific control target and the parameter needs to be adjusted according to the characteristics of the control target. This is a case where the control result changes due to a change in the control target and a change over time. In either case, a large change occurs in one or more values of the control result information. (Here, it is assumed that the initial control in which the controller is installed as a control target is also a case where the control result information has changed from a state in which nothing is recorded.)
In other words, after the adjustment work is finished, the same control operation is repeated, for example, in the normal operation of the manufacturing process, and the calculated control operation until the control operation changes due to deterioration or failure of the control-related equipment. It is considered that the feature amount data for each item has low importance for the user.

  That is, in a series of repeated control operations, if no change of a certain value or more in consideration of noise or the like appears in one or more of the above control result information, writing to the EEPROM is not performed and the number of times of writing is determined. I thought that reducing it is effective for solving the problem.

  Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings. FIG. 1 is a diagram illustrating an instrumentation example of a controller according to the present embodiment.

  The controller 1 controls the temperature of the object to be heated 8 provided in the heat treatment furnace 6. In the heat treatment furnace 6, an object to be heated 8, a temperature sensor 5 for measuring temperature, and a heater 4 for heating are provided. In the controller 1, a set value SP that is a target temperature is set. This set value SP is specified by the user, for example. Alternatively, the set value SP may be transferred to the controller 1 from a PC (personal computer) or the like. Further, the measured temperature measured by the temperature sensor 5 is input to the controller 1 as the control amount PV. The controller 1 performs feedback control based on the set value SP and the control amount PV. That is, the controller 1 performs control so that the measured value PV (measured temperature) approaches the preset value SP (target temperature).

  In the present embodiment, the controller 1 performs PID control. In this case, the PID parameter corresponds to the control parameter. The controller 1 outputs an operation amount MV corresponding to the PID parameter to the electric power device 7. Therefore, the controller 1 controls the electric power device 7 according to a preset value of the PID parameter. Then, the power supplied from the power device 7 to the heater 4 is adjusted. That is, power corresponding to the operation amount MV is supplied from the power device 7 to the heater 4. Accordingly, the power device 7 supplies current to the heater 4 with a control output corresponding to the operation amount MV. Thereby, the article 8 to be heated in the heat treatment furnace 6 is heated, and the control amount PV measured by the temperature sensor 5 is controlled so as to approach the set value SP. That is, the measured temperature approaches the target temperature.

  Next, the controller 1 according to the present embodiment will be described. The controller 1 includes an arithmetic processing unit 11, an EEPROM 12, and a RAM 13. The arithmetic processing unit 11 is an arithmetic processing unit and executes a program stored in the EEPROM 12 or other ROM (not shown). The arithmetic processing unit 11 performs arithmetic processing using the set PID parameter. The RAM 13 temporarily stores values necessary for the calculation of the calculation processing unit 11 and values obtained by the calculation of the calculation processing unit 11. For example, the RAM 13 stores the measured temperature measured by the temperature sensor 5 as the control amount PV. Further, the RAM 13 holds a feature amount for the control response.

  The EEPROM 12 is an electrically rewritable nonvolatile memory, and stores PID parameters, control programs, and the like. For example, data rewriting is executed by erasing data already written in the EEPROM 12 and writing new data. The EEPROM 12 usually has a limit on the number of times of writing. The arithmetic processing unit 11 writes and reads data to and from the EEPROM 12 and RAM 13.

  The arithmetic processing unit 11 executes a program for calculating the operation amount MV. Specifically, the arithmetic processing unit 11 performs a PID calculation using the PID parameter, and calculates an operation amount MV. That is, the operation amount MV determined to be appropriate is obtained from the set value SP and the control amount PV. When the controller 1 outputs the operation amount MV to the power device 7, the power device 7 supplies the heater 4 with power corresponding to the operation amount MV. Thereby, the article 8 to be heated in the heat treatment furnace 6 is heated. Therefore, the control amount PV is controlled so as to approach the set value SP. Thus, feedback control is performed by executing the PID calculation based on the control amount PV and the set value SP to obtain the operation amount MV.

  The arithmetic processing unit 11 further executes a program for automatically detecting the feature amount of the control response. The user can adjust the PID parameter by checking the feature amount. That is, a feature amount necessary for setting the PID parameter is extracted from the control response. Then, this feature amount is written in the EEPROM 12. Further, the user confirms the feature amount and changes the PID parameter.

  More specifically, the feature amount calculated by the arithmetic processing unit 11 is sequentially written in the RAM 13. That is, during the control operation, each time a feature amount is extracted, its value is written into the RAM 13. The feature amount is once held in the RAM 13 and then written in the EEPROM 12. That is, after the feature value calculation operation for the latest control response is completed, the feature values are transferred from the RAM 13 to the EEPROM 12. The feature amount written in the RAM 13 is read out and transferred to the EEPROM 12. Here, after satisfying an arbitrary completion condition of the feature quantity calculation operation (for example, when all feature quantities for the control response are extracted or when the settling judgment condition for the control set value SP is satisfied), the EEPROM 12 Is written to. That is, a control operation is performed for a certain period, and during the control operation, sequentially calculated feature amounts are first written in the RAM. Then, after the feature amount calculation operation is completed, writing of the feature amount from the RAM 13 to the EEPROM 12 is started.

  Since the controller 1 has memory limitations, it is practical to reserve an area in the EEPROM 12 where a feature amount is written in advance and reuse it. The feature amount is overwritten in the same area of the EEPROM 12. It will be followed. What is stored in the writing area on the EEPROM 12 immediately before the feature data stored in the RAM 13 is written in the EEPROM 12 is the data of the feature calculated in the past control operation. The feature amount data held in the EEPROM 12 is a past control response until the feature amount data held in the RAM 13 is written in the writing area of the EEPROM 12 after the feature amount calculation operation is completed. The feature amount data stored in the RAM 13 is data for a new control response. Hereinafter, the feature amount data held in the EEPROM 12 may be referred to as old data, and the feature amount data held in the RAM 13 may be referred to as new data.

  Further, the arithmetic processing unit 11 determines whether or not the feature amount data is transferred from the RAM 13 to the EEPROM 12. That is, the arithmetic processing unit 11 compares the feature amount data for the past control response already written in the EEPROM 12 with the feature amount data for the latest control response written in the RAM 13 to determine the similarity of the feature amount. In accordance with the determination result, it is determined whether or not the feature amount data is transferred from the RAM 13 to the EEPROM 12. Specifically, when the similarity between the new data and the old data is high, the feature amount data written in the RAM 13 is not written in the EEPROM 12. Thereby, the number of times of writing can be suppressed. As a method for determining similarity, for example, the arithmetic processing unit 11 calculates a difference between new data and old data for each feature amount, and when the difference value exceeds a threshold value, the new data on the RAM 13 is stored in the EEPROM 12. Overwrites the write memory area that holds the old data. On the other hand, if the difference value does not exceed the threshold value, the overwriting process is not performed. Therefore, the old data is retained in the EEPROM 12. The arithmetic processing unit 11 performs the above processing using a predetermined arithmetic processing program.

  Next, an example of feature amounts that are automatically detected will be described with reference to FIG. FIG. 2 shows an example of a control response waveform when control is performed by the controller 1. That is, FIG. 2 is an example showing the temperature rise characteristics when PID control is executed. In FIG. 2, the horizontal axis indicates time (sec), and the vertical axis indicates the temperature (° C.) that is the control amount PV. In addition, FIG. 2 shows an example of a control response waveform by the latest control operation and a control response waveform by the past control operation.

  When the set value SP is changed, the temperature rise control is started. In FIG. 2, the temperature rise start time is 0 sec. The control amount PV of the temperature rise start time is PVi. For example, it is assumed that the setting value SP is changed from room temperature 20 (° C.) to 100 (° C.). At this time, since the control amount PV is lower than the set value SP, the controller 1 outputs a high value of the operation amount MV. Then, the inside of the heat treatment furnace 6 is heated by heater heating, and the control amount PV eventually reaches the set value SP. Here, the time from the control start point until the control amount PV coincides with the set value SP is the set value arrival time (sec), and this set value arrival time is one of the feature amount data. Here, the set value arrival time held in the RAM 13 is Ar, and the set value arrival time held in the EEPROM 12 is Ae. That is, the new data of the set value arrival time is Ar, and the old data is Ae.

  Thereafter, in the example of FIG. 2, the control amount PV continues to increase even after the control amount PV reaches the set value SP. However, due to the control operation of the controller 1, the value of the control amount PV that exceeds the set value SP eventually changes from increasing to decreasing, and the control amount PV approaches the setting value SP again. Here, the difference between the maximum value of the control amount PV and the set value SP is the overshoot amount (° C.), and this overshoot amount is one of the feature amount data. In FIG. 2, the overshoot amount held in the RAM 13 is Br, and the overshoot amount held in the EEPROM 12 is Be. That is, the new data of the overshoot amount is Br and the old data is Be.

  Further, in the control response waveform by the past control operation of FIG. 2, the control amount PV shows a phenomenon of hunting that repeatedly rises and falls periodically after overshooting. Here, the cycle of the increase and decrease of the control amount PV is the hunting cycle (sec), and this hunting cycle (sec) is one of the feature amount data. As a method of calculating the hunting cycle, there is a method in which the time at which the maximum point of the control amount PV during hunting appears is calculated, the time between adjacent maximum points is calculated, and the average value of the time between the maximum points is used as the hunting cycle. is there. Here, the hunting cycle held in the RAM 13 is Cr, and the hunting cycle held in the EEPROM 12 is Ce. That is, the new data of the hunting cycle is Cr, and the old data is Ce. In the latest control operation, Cr is not detected because the hunting cycle is long or substantially not detected (that is, hunting does not occur).

  Such an overshoot amount, hunting cycle, and set value arrival time are calculated as feature amounts and used for adjusting control parameters such as PID. For example, in the ideal temperature rise characteristic, the amount of overshoot is small, the hunting cycle is long or not substantially detected (that is, hunting does not occur), and the set value arrival time is shortened. Therefore, the PID parameter can be adjusted by the user confirming these feature amounts. Note that by using the feature amount, it is not necessary to store a large amount of time-series data of the control amount PV measured at each control cycle, and a necessary memory size can be reduced.

  The feature amount data thus detected is sequentially stored in the RAM 13. After the feature amount calculation operation is completed, it is checked whether or not the new data in the RAM area is stored in the EEPROM area. The EEPROM 12 has a size required for writing the overshoot amount, the hunting cycle, and the set value arrival time, and old data that is characteristic amount data of the past control operation is written therein. The controller 1 performs a similarity check based on the new data on the RAM 13 and the old data on the EEPROM 12, and determines whether or not to write the new data on the RAM 13 in the EEPROM 12 according to the result.

  When the old and new data are similar, the new data on the RAM 13 is not written on the EEPROM 12. If the old and new data are not similar, the new data is written into the EEPROM 12. As a result, new data is overwritten on the EEPROM 12. By comparing similarities in this way, it is possible to limit the writing of feature amount data that is determined to be less important for the user. In other words, if there is no significant difference in the feature data between the new data and the old data, it is determined that the user does not need the feature data, for example, during normal operation after control parameter adjustment. Therefore, the new data is not stored in the EEPROM 12. Therefore, the number of times of writing can be reduced. Thereby, it is possible to extend the normal operation period of the EEPROM 12 until a failure occurs due to the limitation on the number of times of writing. On the other hand, if there is a large difference in feature values between the new data and the old data, for example, during control parameter adjustment work, including when the control system is introduced, or due to deterioration or failure of control-related equipment, It is determined that the user needs feature data, such as when a change appears, and new data is written to the EEPROM 12. As a result, the normal operation period of the EEPROM 12 is extended until the failure occurs depending on the number of times of writing while the feature value data determined to be valid for the user is left on the EEPROM 12. A case where the similarity becomes high during control parameter adjustment, that is, a case where a large change in the control response does not appear even when the control parameter is changed will be described. At this time, the user repeatedly changes the control parameter and executes the control operation until the control response changes (that is, until the similarity becomes low), and when the change appears in the control response (that is, the similarity becomes similar). When the value becomes low), the control response parameter having the feature amount data closer to the adjustment target is selected. Since the feature amount data detected at this time has low similarity, the old data on the EEPROM 12 is overwritten and held. In order to further improve the control response, the user repeats the change of the control parameter and the execution of the control operation in the same manner. From the operations, the control parameter at the time when the feature amount data that seems to be closest to the adjustment target is detected is selected to complete the adjustment. This is a case where a set of feature value data of control responses with high similarity is continuously detected, and the importance of overwriting and retaining new feature value data on the EEPROM 12 is low. Note that information such as the number of control operations corresponding to the control response in which new data on the RAM 13 is not overwritten on the EEPROM 12 by similarity determination and the evaluation function value used for similarity determination are related to the feature amount data on the EEPROM 12. You may also remember it.

  As described above, the controller operating method according to the present embodiment includes a step of calculating a feature amount of the control response based on a measurement result of the control amount, a step of holding the calculated feature amount in the RAM area, When the feature value data newly held in the RAM area is written to the EEPROM 12, the past feature value data held in the EEPROM 12 and the new feature value data held in the RAM area are used to store the RAM. Determining whether to write data from the area to the EEPROM 12. For example, it is determined whether or not to write data from the RAM 13 to the EEPROM 12 according to the difference value between the previous feature value data written in the EEPROM 12 and the current feature value data held in the RAM 13. If the difference value does not exceed the threshold value, the feature value data is stored in the EEPROM 12.

  Next, an example of similarity comparison will be described. In the control response shown in FIG. 2, it is assumed that Ae = 105 sec, Be = 10 ° C., and Ce = 20 sec are acquired as old data. Further, it is assumed that Ar = 100 sec, Br = 20 ° C., and Cr = N are acquired as new data. Note that N of the hunting cycle is a value indicating non-detection. For example, N indicates a case where the hunting cycle is too long to be detected.

Example 1
Processing in the first embodiment will be described with reference to FIG. FIG. 3 is a diagram for explaining processing for comparing similarities. In the first embodiment, the similarity is compared for each feature amount. As shown in FIG. 3, the EEPROM 12 stores old data Ae, Be, and Ce. On the other hand, the RAM 13 stores new data Ar, Br, and Cr.

  In this embodiment, the similarity between old and new data corresponding to all feature quantities to be detected is described as Sj, and the similarity between old and new data corresponding to each feature quantity is described as Sja, Sjb, and Sjc. The description of the similarity of each feature quantity is described by adding subscripts (a, b, c, etc.) corresponding to each feature quantity. Similarity Sj is determined using similarity Sja, Sjb, Sjc for each feature quantity. The similarity Sj, Sja, Sjb, Sjc takes a value of 0 or 1. When 1, the similarity is low, and when 0, the similarity is high. Specifically, when the similarity is low in one or more feature quantities, that is, when any of the similarities Sja, Sjb, and Sjc is 1, it is determined that the similarity Sj = 1, and the feature of the RAM 13 The amount of data is overwritten on the EEPROM 12. On the other hand, when the similarity is high in all the feature amounts, that is, when all of the similarities Sja, Sjb, and Sjc are 0, it is determined that the similarity Sj = 0, and the feature amount data in the RAM 13 is written in the EEPROM 12. Absent. That is, when the change is large with respect to one or more feature amounts, the feature amount data in the RAM 13 is overwritten in the EEPROM 12.

  More specifically, a threshold value Ts is set for each feature amount, and when the absolute value of the data difference for each feature amount exceeds the threshold value Ts, it is determined that the similarity is low. In this embodiment, the threshold value Ts set for each feature quantity is described as Tsa, Tsb, Tsc by adding subscripts (a, b, c, etc.) corresponding to each feature quantity. For example, in the case of the set value arrival time, the absolute value of (Ae-Ar) is compared with Tsa which is a threshold value of the set value arrival time. When the absolute value of (Ae−Ar) exceeds the threshold value Tsa, Sja = 1 is set, and when the absolute value is equal to or less than the threshold value Tsa, Sja = 0 is set. Sja is a value indicating the similarity in the set value arrival time. In the set value arrival time, when Sja = 1, the similarity between old and new data is low, and when Sja = 0, the similarity between old and new data is high.

  Similarly, in the case of the overshoot amount, the absolute value of (Be−Br) is compared with the threshold value Tsb. When the absolute value of (Be−Br) exceeds the threshold value Tsb, Sjb = 1 is set, and when the absolute value is equal to or less than the threshold value Tsb, Sjb = 0 is set. Sjb is a value indicating similarity in the amount of overshoot. With respect to the amount of overshoot, the similarity between old and new data is low when Sjb = 1, and the similarity between old and new data is high when Sjb = 0.

  Similarly, in the case of the hunting cycle, the absolute value of (Ce−Cr) is compared with the threshold value Tsc. When the absolute value of (Ce−Cr) exceeds the threshold value Tsc, Sjc = 1, and when the absolute value is equal to or less than the threshold value Tsc, Sjc = 0. Sjc is a value indicating similarity in the hunting cycle. In the hunting cycle, when Sjc = 1, the similarity between old and new data is low, and when Sjc = 0, the similarity between old and new data is high.

  When the feature amount is not detected, for example, when one of the old and new data is not detected and the other is detected, the similarity is low. That is, it is assumed that the similarity is low when the feature amount is switched from undetected to detected, or when the feature amount is switched from detected to undetected. Taking a hunting cycle as an example, Sjc = 1. If both new and old data are not detected, the similarity is high. In other words, taking a hunting cycle as an example, if Cr = Ce = N, Sjc = 0.

  If any one of Sja, Sjb, and Sjc is 1, Sj = 1. That is, when the similarity of one or more feature quantities is low, it is determined that the old and new data are not similar, and the data in the EEPROM 12 is overwritten. If all the feature quantities are similar, writing to the EEPROM 12 is not performed. Thereby, the number of times of writing to the EEPROM 12 can be reduced, and the normal operation period due to the limitation of the number of times of writing can be extended.

  Of course, different threshold values can be set for each feature amount. Further, the threshold value Ts can be set according to the value stored in the EEPROM 12. For example, the threshold value Ts is variable, and Tsa = Ae × 10%, Tsb = (SP−Pvi) × 5%, and Tsc = Ce × 3%. As described above, each threshold value may be set by using the feature amount data stored in the EEPROM 12. By doing so, it is possible to set the threshold value Ts in consideration of the resolution for each feature value data. Of course, the setting of the threshold value Ts is not limited to the above example. The threshold value Ts may be a value that considers noise that affects each feature amount.

  Considering the case where similarity is determined by applying the variable threshold value to the new and old data of the first embodiment, Asa = 105 sec, Ar = 100 sec, and Tsa = 10.5 sec. In this case, | 105-100 | ≦ 10.5, and Sja = 0. Therefore, the similarity between the old and new data is high in the set value arrival time.

  Further, when Be = 10 ° C., Br = 20 ° C., SP = 100 ° C., and PVi = 20 ° C., Tsb = 4 ° C. In this case, | 10−20 | ≧ 4 and Sjb = 1. Therefore, the similarity between old and new data is low in the overshoot amount.

  In the old data, the hunting cycle is not detected, but in the new data, it is detected. Therefore, the similarity between old and new data is low in the hunting cycle, and Sjc = 1. From the above values of Sja, Sjb, and Sjc, Sj is 1, and it is determined that the similarity is low. As a result, the new data in the RAM 13 is overwritten with the old data in the EEPROM 12, and the feature data is updated. Further, as in the above example, since the comparison value between the difference value of the feature amount data and the threshold value is used, it can be easily determined. In the above example, when it is determined that the similarity is low with respect to one feature amount, that is, any one of Sja, Sjb, and Sjc, the EEPROM 12 is overwritten with new data in the RAM 13. Good. Thereby, it can determine rapidly.

(Example 2)
Processing in the second embodiment will be described with reference to FIG. FIG. 4 is a diagram for explaining processing for comparing similarities. In Example 2, the similarity is compared using an evaluation function. As shown in FIG. 4, the EEPROM 12 stores old data Ae, Be, and Ce. On the other hand, the RAM 13 stores new data Ar, Br, and Cr. The new and old data values (Ae, Be, Ce, Ar, Br, Cr) are the same as those in the first embodiment, and the description of the same processing as in the first embodiment is omitted.

  In the present embodiment, the similarity Sj is determined based on the similarity Sjt of the time dimension and the similarity Sjp of the temperature dimension, and it is determined whether or not new data in the RAM 13 is overwritten in the EEPROM 12. . Here, the time dimension similarity Sjt is a value of the evaluation function described using the set value arrival time and the hunting period. The set value arrival time and the hunting cycle are feature quantities represented by time dimensions. The similarity Sjp of the temperature dimension is a value of the evaluation function described using the overshoot amount. The overshoot amount is a feature amount expressed by a temperature dimension. In this way, an evaluation function is set for each dimension. If the similarity of one or more dimensions exceeds the threshold value among the similarities Sjp and Sjt calculated using the evaluation function for each dimension, it is determined that the control responses corresponding to the old and new data are not similar. To do.

The similarity Sjt of the time dimension is expressed by the evaluation function shown below.
Sjt = α × | Ae−Ar | + β × | Ce−Cr |

  Α and β are weighting factors. That is, in each feature amount, a weighting coefficient is applied to the absolute value of the difference value between the old and new data. And the sum of them becomes the similarity Sjt. The similarity Sjt of the time dimension is compared with the threshold value Tst. As described above, the similarity Sjt of the time dimension is represented by an evaluation function having the set value arrival time and the hunting cycle as variables.

  The similarity Sjp of the temperature dimension is | Be-Br |. That is, the absolute value of the difference value between the old and new data in the overshoot amount becomes the similarity Sjp of the temperature dimension. Then, the similarity Sjp of the temperature dimension is compared with the threshold value Tsp.

  When the similarity of one or more dimensions among the calculated similarities of each dimension exceeds a corresponding threshold value, it is determined that the old and new data are not similar. That is, when the similarity of a certain dimension exceeds the threshold, it is determined that the old and new data are not similar, and Sj = 1 is set. As a result, new data in the RAM 13 is overwritten on the EEPROM 12. It is possible to leave on the EEPROM 12 the feature amount data judged to be effective for the user. On the other hand, when Sjt ≦ Tst and Sjp ≦ Tsp, it is determined that the old and new data are similar, and Sj = 0. That is, when the similarity of all dimensions does not exceed the threshold value, it is determined that the old and new data are similar, and Sj = 0. In this case, overwriting of new data in the RAM 13 to the EEPROM 12 is not executed. Thereby, the number of times of writing to the EEPROM 12 is limited, and the normal operation period of the EEPROM 12 until the failure occurs due to the limitation of the number of times of writing is extended. Of course, different thresholds can be set for the evaluation function of each dimension.

  As with the feature value data used in the present embodiment, for any feature value used in the evaluation function for determining similarity Sj, if one of the old and new data is not detected and the other is detected, the similarity is similar. Suppose that the nature is low. That is, when the feature amount is switched from non-detection to detection, or when the feature amount is switched from detection to non-detection, it is determined that the similarity is low, and Sj = 1. Here, when the data of the feature amount is not detected for both new and old, the same processing is performed as if the old and new data were arbitrarily the same value. For example, in the second embodiment, considering the case where the new and old data of the hunting cycle are not detected, Ce = Cr = 0 is set, and the similarity Sjt which is the value of the evaluation function is calculated. Here, when neither the new value nor the old data is detected for the set value arrival time, Ae = Ar = 0 and the time dimension similarity Sjt is 0.

  Of course, different threshold values can be set for each feature amount. Further, the threshold value Ts can be set according to the value stored in the EEPROM 12. That is, the threshold value Ts is made variable. For example, Tst = Ae × 10% and Tsp = (SP−Pvi) × 5%. By doing so, it is possible to make a determination in consideration of the resolution. Of course, the setting of each threshold value Ts is not limited to the above example. Further, a value considering noise that affects each dimension may be used.

  The first embodiment is an example in which the hunting cycle is changed from non-detection to detection between new and old data of feature amounts. Therefore, it is determined that the old and new data are not similar. Therefore, new data in the RAM 13 is written in the EEPROM 12 and the feature value data in the EEPROM 12 is updated. In the above example, data may be written to the EEPROM 12 when one evaluation function exceeds a threshold value.

  As described above, by setting the evaluation function for each dimension, it is possible to comprehensively determine the feature amount related to each dimension. of course. The evaluation function may not be set for each dimension. In this case, it is preferable to use a value obtained by standardizing each feature amount with a maximum value or the like. The setting of the evaluation function is not limited to the above example. The feature amount data used for calculating the evaluation function may be all of a plurality of feature amount types to be calculated by the controller 1, or may select a feature amount type having high importance.

  Note that the characteristic amount of the control response is not limited to the hunting period, the overshoot amount, and the set value arrival time, and may be, for example, an undershoot amount, an inclination during heating, or the like. Further, in the first and second embodiments, the similarity is determined by binary values of 0 and 1. However, two or more stages are provided for the similarity, and the memory operation method and the holding method are changed according to the values. May be. Furthermore, the PID parameter and other control parameters may be handled in the same manner as the feature amount. A non-volatile memory other than EEPROM may be used. Furthermore, you may utilize for control apparatuses other than the controller 1. FIG. That is, any control device that outputs an operation amount obtained using a control parameter to a control target so that a measured value approaches a set value can be used. Further, the controller 1 may control the physical quantity other than the temperature, for example, the flow rate, the pressure or the like.

It is a figure which shows the structure of the controller concerning this Embodiment, and its instrumentation example. It is a figure which shows a typical control response waveform. FIG. 6 is a diagram for explaining data write processing according to the first embodiment; FIG. 10 is a diagram for explaining data write processing according to the second embodiment;

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Controller 4 Heater 5 Temperature sensor 6 Heat processing furnace 7 Electric power equipment 8 To-be-heated object 11 Arithmetic processing part 12 EEPROM
13 RAM
SP set value MV manipulated variable PV controlled variable

Claims (10)

A control device that outputs an operation amount according to a control parameter to a control target so that a measured value approaches a set value,
An arithmetic processing unit that calculates a feature amount of a control response based on the measured value;
A RAM area in which data of the feature amount calculated by the arithmetic processing unit is held;
A rewritable nonvolatile memory in which the feature amount data held in the RAM area is written;
When writing the feature value data newly held in the RAM area to the nonvolatile memory, the past feature value data held in the nonvolatile memory and the new feature value held in the RAM area A control device that determines whether to write data from the RAM area to the non-volatile memory using the data.   A difference value between the past feature amount data and the new feature amount data is calculated for each feature amount, and it is determined whether or not to write from the RAM area to the nonvolatile memory according to the difference value. The control device according to claim 1.   An evaluation function value is calculated using the past feature value data and the new feature value data, and whether or not to write to the nonvolatile memory from the RAM area according to the evaluation function value is determined. The control device according to claim 1, wherein the control device is determined. When a value corresponding to the difference between the past feature amount and the new feature amount exceeds a threshold value,
The control device according to claim 1, wherein the control device writes data from the RAM area to the nonvolatile memory.   The control device according to any one of claims 1 to 4, wherein the threshold value changes according to a value stored in the nonvolatile memory. Having rewritable nonvolatile memory,
An operation method of a control device that outputs an operation amount according to a control parameter to a control target so that a measured value approaches a set value,
Calculating a characteristic amount of the control response;
Holding the feature quantity in a RAM area;
When writing the feature value data newly held in the RAM area to the nonvolatile memory, the past feature value data held in the nonvolatile memory and the new feature value held in the RAM area And determining whether to write data from the RAM area to the non-volatile memory using the data.   A difference value between the past feature amount data and the new feature amount data is calculated for each feature amount, and it is determined whether or not to write from the RAM area to the nonvolatile memory according to the difference value. The operation method of the control device according to claim 6.   A value of an evaluation function using the past feature value data and the new feature value data is calculated, and whether to write out from the RAM area to the nonvolatile memory is determined according to the value of the evaluation function The operation method of the control apparatus according to claim 6 or 7. When a value corresponding to a difference between the past feature amount data and the new feature amount data exceeds a threshold value,
The operation method of the control device according to claim 6, wherein data is written from the RAM area to the nonvolatile memory.   The operation method of the control device according to claim 6, wherein the threshold value changes according to a value stored in the nonvolatile memory.

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