JP2006042473A - Autonomous designing method of motor control system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten a time for a position command to an object to be controlled having the vibration of a machine base and a time for the tuning work of a compensator. <P>SOLUTION: This autonomous designing method of the motor control system is configured such that a positioning control system is constituted to the object to be controlled having the vibration of the machine base mounted with a device driven by a motor by using position information related to the rotation position or the motor or the position of a movable part of the device. With respect to a specified moving distance of the movable part of a plurality of the moving distances, there are autonomously designed by using an optimization means: a feed forward compensator that is, (1) satisfied in positioning specification, (2) considered in a control target related to the suppression of the vibration of the machine base, (3) considered in safety on operation, (4) and secured in the safety of a feedback compensator; the feedback compensator; and a position command parameter. A genetic algorithm is used as the optimization means. The search range of a feedback compensator parameter is set so as to include a stabilization compensator parameter that is set initially or set after shipment. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an autonomous design method for an electric motor control system that autonomously designs position commands and compensator parameters for a controlled object having machine vibration.

  In an equipment machine represented by an electronic component automatic mounting machine or the like, a control target including a motor and a drive mechanism connected to the motor and a machine supporting the drive mechanism connected to the motor has a spring characteristic. In some cases, the acceleration / deceleration operation causes mechanical vibration, which increases positioning time and degrades positioning accuracy. Further, the occurrence of machine base vibration may adversely affect the environment around the machine.

  When searching for a solution by the servo control method for the positioning control problem having these machine stand vibrations, the following several methods can be considered.

(A) State feedback control Machine vibration is regarded as an unobservable state quantity, and state feedback control is performed by combining a state estimator using an observer, a Kalman filter, etc. with an optimal regulator from a part of the observed quantity.

(B) Feed-forward control Considering the transfer characteristics of machine vibration, a compensator that can reduce the vibration is designed. When machine vibration appears explicitly in the controlled variable, transfer characteristics up to the controlled variable are modeled and applied to two-degree-of-freedom model matching control and zero phase difference control.

(C) Devise of target trajectory (position command) Each position command generation algorithm analyzes the power spectrum distribution characteristics of the position command when designing the target trajectory, and a position command algorithm that can suppress machine vibration. Select that parameter.

(D) Auto-tuning The parameters of the compensator are auto-tuned (see Patent Document 1 below). In addition, an online identification mechanism is also used.

  By selecting and applying an appropriate method from the methods (A) to (D), it can be expected to improve the machine vibration suppression effect, but on the other hand, sufficient results may not be achieved. There is also.

  Looking at the characteristics of each control method, for example, the methods (A) and (B) are based on the premise that the position command trajectory is designed in advance by some method. There is a problem that it depends on the trajectory.

  On the other hand, for the method (C), if the movable part completely follows the trajectory of the position command, the drive characteristics of the movable part will also have a desired spectral distribution. To find the trajectory of the position command that satisfies the constraints of the machine such as torque and gives the optimal solution to the above-mentioned adverse effects on the surrounding environment of the machine and the problem of deterioration of positioning accuracy, focus only on the characteristics of the position command. Often insufficient. In addition, when a control law such as a complete tracking method is not applied, the drive characteristics of the movable part may be different from the characteristics of the position command, and there is actually a region of trial and error to obtain the desired characteristics. Yes. That is, in the conventional framework in which the compensator and the position command are individually designed, it is not easy to search for an optimal solution that satisfies the control specifications.

  The same can be said for the method (D), and the solution derived by the conventional framework is not necessarily an optimal solution.

In addition, when applying these methods to positioning systems with machine vibration, there has not been a method with a clear design rule for the control target in the past, which makes the design work by trial and error more difficult. It was also a factor.
Japanese Patent Laid-Open No. 2001-8477 (pages 2 to 5 etc.)

  In order to solve the above-described conventional problems, the present inventors have studied an autonomous design method for an electric motor control system described in the specification of Japanese Patent Application No. 2003-27880 (hereinafter referred to as “prior application specification”). is doing. This autonomous design method is characterized in that the time for searching for the optimal solution can be shortened compared to the conventional method by performing the simultaneous optimization design of the position command and the compensator using the genetic algorithm (GA). is there. However, in the embodiment described in the specification of the previous application, the feedback compensator is fixed without performing the autonomous design, and a specific autonomous design method thereof is not disclosed.

  When the autonomous design of the embodiment described in the specification of the prior application is performed, the design flowchart of FIG. 13 is obtained. In this design flowchart method, even if the feedforward compensator and position command are autonomously designed, if satisfactory results cannot be obtained due to insufficient performance of the feedback compensator, redesign of the feedback compensator It becomes necessary, and readjustment of the position command / feedforward compensator must be performed as necessary, which complicates parameter design. For this reason, there exists a problem that the time of the position instruction | command with respect to the control object which has machine stand vibration, and the tuning operation | work of a compensator becomes long.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an autonomous design method for an electric motor control system that can shorten the time required for tuning a position command and a compensator for a controlled object having machine base vibration.

  In order to achieve the above object, the present invention uses position information related to the rotational position of the electric motor or the position of the movable part of the apparatus with respect to a controlled object having vibration of a machine base equipped with the apparatus driven by the electric motor. In the autonomous design method of the motor control system that constitutes the positioning control system, (1) the positioning specification is satisfied for the specific moving distance or a plurality of moving distances of the movable part, and (2) the vibration of the machine base is suppressed. Considering the control target, (3) Considering operational safety, (4) Feedforward compensator and feedback compensator that ensure the stability of the feedback compensator, and position command parameters using the optimization method It is designed. In this way, as shown in FIG. 14, the simultaneous optimization design of the position command, the feedforward compensator, and the feedback compensator that enables the autonomous design of the feedback compensator can be realized. Design / adjustment can be performed by autonomous design, and a feedback process as shown in FIG. 13 becomes unnecessary. As a result, it is possible to shorten the time required for the position command and the compensator tuning operation for the controlled object having the machine vibration, and the position command according to the machine vibration characteristic change, which has higher control performance than the conventional one. And a control system that autonomously designs the compensator parameters can be constructed.

  In this case, a genetic algorithm (GA) may be used as an optimization method. By using this genetic algorithm, it is possible to design a highly accurate parameter even with a relatively small number of measurements. The genetic algorithm is processed through the following steps.

[Initial process]
An initial population corresponding to a predetermined number of individuals is generated, which is composed of a feedforward compensator, a feedback compensator, and chromosomes for storing position parameters.
Further, the search range of the feedback compensator parameter is set so as to include the stabilization compensator parameter that is initialized or set after shipment.

[First step]
The fitness is evaluated using the response result of the simulator circuit unit for each individual as an input value of the evaluation function. In the simulator circuit unit, two types of circuits are configured: a frequency response circuit unit for evaluating the stability of the feedback compensator and a time response circuit unit for evaluating the time response performance.

  The frequency response circuit unit complements the frequency response of the loop transfer function using the frequency response data from the motor current value input command stored in advance to the observed position and the feedback compensator specified by the individual information. Calculate the frequency response of the sensitivity function.

  Further, an evaluation criterion that gives a penalty when the frequency response of the circuit transfer function calculated by the frequency response circuit unit falls below the target stability margin value, and the frequency of the complementary sensitivity function calculated by the frequency response circuit unit A feedback stability evaluation function is set for the response, together with an evaluation criterion that gives a penalty when the target peak gain is exceeded.

[Second step]
Parent individuals are selected so that many individuals with high evaluation remain based on fitness.
[Third step]
Next-generation chromosome candidates are generated by crossing the chromosomes of the parent individuals selected in the second step. [Fourth process]
A mutation is determined for the next generation chromosome candidate generated in the third step, and the result of execution is reflected in the next generation chromosome candidate.

[Fifth step]
Individuals with the best fitness in the population are kept in the elite as they are, and other generations of chromosome candidates are stored in the parent individual's chromosomes.
[Sixth step]
The first to fifth steps are repeated for any number of generations.

[Seventh step]
It repeats from the initial step to the sixth step up to an arbitrary number of trials, and after completion, provides chromosome information of the individual with the best fitness to the positioning control system as a simultaneous optimization parameter of the position command and the compensator.
Through the above steps, the feedforward compensator, the feedback compensator, and the position command parameter are autonomously designed using an optimization method.

  In addition, when evaluating the fitness in the first step, there are an evaluation standard that gives a penalty when the positioning specification is not satisfied, an evaluation standard that gives a penalty when there is a possibility of danger in operation, and a positioning specification. Although we are satisfied, by adding the evaluation function that has an evaluation criterion that gives a penalty for the factor that degrades the positioning performance and the machine vibration suppression performance, and the feedback stability evaluation function, It is recommended to evaluate the fitness of individuals. Thus, if the evaluation function combining the three types of evaluation criteria and the feedback stability evaluation function are added together, the fitness can be evaluated with high accuracy.

  The present invention is implemented based on the conceptual diagram of FIG. The positioning control device 11 mainly includes a position command generation unit 12, a position control unit 13, and a parameter storage unit 14. The control object 16 integrated with the machine base 15 (see FIG. 2) is a rigid system or a resonance vibration system having a spring characteristic between the electric motor 17 and the movable part 18, and the machine base 15 is a movable part 18. If the load torque generated during the acceleration / deceleration operation causes elastic deformation, and if the reaction of the load torque cannot be absorbed, vibration depending on the natural frequency of the machine base 15 may occur.

  Under this circumstance, the present invention optimizes the position command parameters and the parameters of the feedforward compensator 25 and the feedback compensator 26 based on the control specifications described in the claims. When performing this optimization, the autonomous design device 19 is used. The autonomous design device 19 employs a genetic algorithm (hereinafter abbreviated as “GA”), and further enables simultaneous optimization processing of the position command, the feedforward compensator 25 and the feedback compensator 26.

  Here, the basic concept of GA processing used in the autonomous design apparatus 19 will be described. This GA process is performed through the following steps according to the flowchart of the GA process shown in FIG.

[Initial process]
An initial population corresponding to the determined number of individuals is generated, which is composed of the feedforward compensator 25, the feedback compensator 26, and chromosomes for storing each parameter of the position command (S1).

  Parameters to be optimized are set for the chromosomes constituting the initial population. At this time, there are parameters for enabling simultaneous optimization of the feedforward compensator 25, the feedback compensator 26, and the position command parameters. Each parameter that defines the trajectory of the position command at a specific moving distance and each parameter that defines the characteristics of the feedforward compensator 25 and the feedback compensator 26 are held as chromosome information.

[First step]
The fitness is evaluated using the response result by the simulator circuit unit 22 for each individual as the input value of the evaluation function (S2).

  As shown in FIG. 4, in the simulator circuit unit 22, there are two types of frequency response circuit unit 31 for evaluating the stability of the feedback compensator 26 and a time response circuit unit 32 for evaluating the time response performance. Configure the circuit.

  The frequency response circuit unit 32 uses the frequency response data from the motor current value input command stored in advance to the observed position and the feedback compensator 26 defined by the individual information, and the frequency response of the round transfer function. And calculate the frequency response of the complementary sensitivity function.

[Second step]
A parent individual is selected so that many individuals with high evaluation remain based on the fitness (S3). At this time, for a specific moving distance or multiple moving distances, (1) satisfy the positioning specifications, (2) consider the control target for machine vibration suppression, and (3) ensure operational safety. (4) The evaluation function has the following three types of evaluation criteria (A) to (C) so that the parameters for ensuring the stability of the feedback compensator 26 have high adaptability. An evaluation function obtained by adding the function and the feedback stability evaluation function is used.

(A) Evaluation standard that gives a penalty when positioning specifications are not satisfied (B) Evaluation standard that gives a penalty when there is a possibility of danger in operation (C) Positioning performance and machine that satisfy the positioning specifications Evaluation criteria for penalizing factors that cause deterioration of table vibration suppression performance

  Due to the nature of the evaluation function, the input value is a positioning control amount, a signal that can be collected in the positioning control device 11, and a machine base acceleration response. The input value to this evaluation function is reproduced by the simulator circuit unit 22. For example, even if a parameter that may cause an operation risk in the GA processing process is generated, there is no fear of damaging the control target 16. In addition, since the response that cannot be collected by the positioning control device 11 after the controlled object 16 is shipped as a product can be reproduced, the autonomous design device 19 can be applied in all situations from the trial production stage of the product to the mass production shipment. Become.

  In addition, the parameter that defines the machine vibration characteristics in the simulator circuit unit 22 can be changed according to the machine vibration response that changes depending on various conditions via the machine vibration identification unit in the autonomous design apparatus 19. Is possible.

[Third step]
Next-generation chromosome candidates are generated by crossing the chromosomes of the parent individuals selected in the second step (S4).
[Fourth process]
A mutation is determined for the next-generation chromosome candidate generated in the third step, and the result of execution is reflected in the next-generation chromosome candidate (S5).

[Fifth step]
The individual with the highest fitness in the group performs elite preservation to leave the parent individual as it is, and other than that, the next generation chromosome candidate is preserved in the parent individual's chromosome (S6).
[Sixth step]
The first step to the fifth step are repeated up to an arbitrary number of generations (S7).

[Seventh step]
It repeats from the initial process to the sixth process up to an arbitrary number of trials, and after completion, positioning control is performed using individual chromosome information of the best fitness as a position command optimization parameter and simultaneous optimization parameters of the feedforward compensator 25 and the feedback compensator 26. To the device 11.

  By the way, the two-degree-of-freedom control system described in the embodiment (1) described in the specification of Japanese Patent Application No. 2003-27880 is a compensator including both a feedback compensator and a feedforward compensator. The target value response characteristic and the feedback characteristic can be designed independently. Here, the role of the feedback compensator in the two-degree-of-freedom control system that must be fulfilled in the actual control target is to reduce the sensitivity of the control system and ensure robust stability. In particular, when the system fluctuates due to the position of the drive unit connected to the electric motor, angular load fluctuation, friction characteristic fluctuation, installation conditions, etc., the above two feedback performances greatly affect the performance of the product.

For example, when configuring a two-degree-of-freedom control system based on the irreducible decomposition expression described in the embodiment (1) of Japanese Patent Application No. 2003-27880, an approximate transfer function from a motor current command to a motor position is expressed as G ^ rm ( s), and the true transfer function Gtm (s) varies in a multiplicative manner by Δ (s) and becomes equal to the approximate function G ^ tm (s), the transfer function from each position command to the motor position is It is expressed by the following relational expression.
{1+ (1 + G ^ tm (s) · C (s)) ⁻¹ · Δ (s)} Grm (s) = G ^ rm (s)

Where C (s) is a feedback compensator.
G ^ rm (s) is a transfer function from the position command to the motor position when the transfer function from the motor current command to the motor position is G ^ tm (s).
Grm (s) is a transfer function from the position command to the motor position when the transfer function from the motor current command to the motor position is Gtm (s).

The change in the target value response characteristic caused by the model error is
(1 + G ^ tm (s) · C (s)) ^-1 · Δ (s)
In order to be expressed, if reduced sensitivity function (1 + G ^ tm (s ) · C (s)) -1, it can be seen that approaches the desired target value response characteristics.

  Actually, the sensitivity reduction in the two-degree-of-freedom control system is devised to reduce the gain of the sensitivity function as much as possible in the band that easily affects the positioning response while looking at the target value response characteristic and Δ (s) characteristic. ing. In the method of Japanese Patent Application No. 2003-27880, it takes a lot of time to implement the feedback compensator design by the mixed sensitivity combining the low sensitivity and the robust stabilization in the two-degree-of-freedom control system.

  Where the bandwidth is higher than the target value response characteristic, if the fluctuation range of Δ (s) is known in advance, a compensator that can be stabilized within that range may be designed, but Δ (s) is Since the hot water existing within the band of the target value response characteristics has both the stability performance and the disturbance suppression performance affect the positioning response, the design difficulty becomes high. Specifically, if the zero cross gain frequency is within the target value response characteristics band, its phase margin has a large effect on the positioning response, so the Δ (s) characteristics and the actual positioning target specifications are taken into account. The phase design must be advanced.

  Further, as described above, Δ (s) perturbs the desired target value response characteristic and causes deterioration of the positioning characteristic. Therefore, it is necessary to reduce the sensitivity as much as possible within a range that does not impair the stability margin. Furthermore, the characteristics near the zero cross gain frequency are often designed by trial and error while actually operating the object to be controlled, and this is caused by the following two circumstances.

  First, considering that there is a part where the position deviation, which is the input of the feedback compensator of the two-degree-of-freedom control system, depends on the position command, the deterioration degree of the positioning response characteristic due to the stability margin is the feedforward part, that is, The effects of position commands and feedforward compensators must also be considered.

  Secondly, when Δ (s) has a nonlinear characteristic in a low frequency region and the influence extends to the vicinity of the zero cross gain frequency, the phase margin cannot be estimated accurately. The best examples are dynamic friction and static friction generated when a ball guide is used as a guide element or a ball screw is used as a power transmission mechanism.

  Under these circumstances, the initial design of the feedback compensator using each feedback control theory that assumes a one-degree-of-freedom system, its validity is the positioning characteristics when a two-degree-of-freedom control system is actually constructed. Therefore, if the positioning response target specification is not satisfied after the autonomous design of Japanese Patent Application No. 2003-27880 is performed, the feedback compensator is redesigned, and the feedback compensator is finely adjusted. Trial and error work to confirm time response was necessary. Moreover, since the result of the fine adjustment is reflected and the autonomous design of the feedforward compensator / position command may be performed again, there is a disadvantage that the parameter adjustment time becomes long.

  In the present invention, functions and circuits for realizing the autonomous design of the feedback compensator 26 are added to the autonomous design apparatus of Japanese Patent Application No. 2003-27880. Hereinafter, features (A) to (D) of the autonomous design apparatus of the present invention will be described.

  (A) The individual chromosome is made to have parameters that define the characteristics of the feedback compensator 26. This is because redesign and adjustment of the feedback compensator 26 can be performed by autonomous design.

  (B) The parameter search range of the feedback compensator 26 is set so as to include the stabilization compensator parameters that are initially set or set after shipment.

  The autonomous design of the feedback compensator in the present invention is implemented when parameters are initially designed by using feedback design techniques in various one-degree-of-freedom systems, or when autonomous design is performed after shipment. In the actual positioning control system, the parameters used in the product are adjusted to the optimum solution given the feedforward compensator and the position command. Therefore, the search range is set so as to include these parameters. By doing so, it is possible to prevent an erroneous search range from being set such that stability cannot be ensured, and it is not necessary to unnecessarily widen the search range, so that the parameter convergence speed can be increased.

  (C) In the simulator circuit unit 22, two types of circuits are configured: a frequency response circuit unit 31 for evaluating the stability of the feedback compensator 26 and a time response circuit unit 32 for evaluating the time response performance. (See FIG. 4).

  Only the parameter information of the feedback compensator 26 is transmitted to the frequency response circuit unit 31. The frequency response circuit unit 31 stores a transfer function from a single or a plurality of motor current value input commands to an observation amount position in order to express a model set necessary and sufficient for evaluating stability.

  By the way, when calculating the round transfer function and the complementary sensitivity function in the frequency response circuit unit 31, if the order of the transfer function increases, the coefficient of the rational polynomial may become too large or too small. Therefore, when the frequency response characteristic is calculated, there is a possibility that numerical overflow or underflow occurs, and the accurate characteristic cannot be calculated.

  As a measure to prevent this deterioration in calculation accuracy, the transfer function from the motor current value input command to the observable position and the frequency response of the compensator are not calculated without using the rational polynomial expression. A method may be used in which characteristics are expressed by complex numbers, and then a final result is obtained by complex number calculation for each frequency.

  Therefore, in the present invention, it is assumed that the transfer function from the motor current value input command to the observation amount position is stored in the memory not in the rational function expression but in the frequency / complex number expression that is the frequency response characteristic. By setting it as such a preservation | save form, the calculation process which converts into a frequency response data from the transfer function of a control object can be skipped beforehand.

  For example, the processing of the frequency response circuit unit 31 when fT transfer functions are registered is performed as follows according to the flowchart of FIG. First, the feedback compensator information of a specific individual is received (step S11). Thereafter, the frequency response data from the motor current value input command to the observation amount position at all locations is loaded (step S12), and the frequency response data of the feedback compensator of the specific individual is created (step S13). Then, after resetting the counter t (step S14), the frequency response data of the t-th round transfer function and the complementary sensitivity function are calculated (step S15). Then, after incrementing the counter t (step S16), it is determined whether or not the value of the counter t exceeds the predetermined value fT (step S17). If the value of the counter t does not exceed the predetermined value fT, the t + 1th The frequency response data of the one-round transfer function and the complementary sensitivity function are calculated. In this way, the process of calculating the frequency response data of the round transfer function and the complementary sensitivity function is repeated up to fT. When the frequency response data of the round transfer function and the complementary sensitivity function has been calculated up to the fT-th, the loop response function and the frequency response data of the complementary sensitivity function at all points (0 to fT-th) are sent to the GA processing unit 21. Transmit (step S16).

As described above, frequency response data for evaluating the feedback performance can be obtained from the simulation circuit unit 22 in the first step of the GA processing unit 21.
(D) An evaluation criterion for giving a penalty using the one-round transfer function and the complementary sensitivity function is added to the evaluation function of the GA processing.

  The stability margin of the loop transfer function and the peak gain of the complementary sensitivity function are calculated from the frequency response data in the first step of the GA processing, and an evaluation function that gives a penalty is set based on the result. By combining this with an evaluation standard in a conventional autonomous design apparatus, it becomes possible to evaluate not only the conventional feedforward compensator / position command but also the fitness of the individual including the feedback compensator.

"Example"
Next, an embodiment in which the present invention is applied to the apparatus shown in FIG. 2 will be described. The apparatus shown in FIG. 2 has a configuration in which a so-called ball screw system in which a ball screw 20 is driven by a servo motor 17 (electric motor) to slide a table 18 (movable part) is mounted on a machine base 15. In the first embodiment, the positioning control device 11 of this ball screw system is configured as shown in FIG. The parameter storage unit 14 is connected to the autonomous design device 19 and transfers necessary parameters to the position command generation unit 12 and the position control unit 13.

  The position command generation unit 12 is equipped with a position command algorithm that can be differentiated three times, and the position command trajectory is determined by the movement distance L, speed V, acceleration A, deceleration D, and jerk rate J. The compensator has a two-degree-of-freedom control system based on the irreducible decomposition expression.

  In FIG. 5, D (s) / Na (s) is the inverse characteristic of the approximate transfer characteristic from the motor current command to the table 18, and Nm (s) / Na (s) is the table 18 from the position of the motor 17. This is the inverse characteristic of the approximate transfer characteristic up to.

  K (s) changes the target value follow-up characteristic so that D (s) / Na (s) and Nm (s) / Na (s) are proper and the vibration of the machine base 15 is suppressed. It is a filter. Cpos (s) is a PID compensator + torque filter. Here, s represents a Laplace transform operator.

  Since the position control unit performs digital control, each compensator is mounted using some discretization technique. In this positioning control device 11, a table positioning time of 650 samples and a positioning completion width of 20 pulses are set as a target positioning specification for a moving distance of 50000 pulses. Since it affects the deviation of the table position, the goal is to drive it as much as possible.

  At this time, in tuning each parameter, D (s) / Na (s) and Nm (s) / Na (s) are fixed, and the parameters L, V, A, D, J of the command that can be differentiated three times, A condition that the parameter defining Cpos (s) is variable was provided.

First, Cpos (s) is a proportional term, a differential term, and a phase term that secures a phase margin of 40 ° and a gain margin of 7 dB using the frequency characteristics from the motor current command at each table position to the motor position collected in advance. The integral term and torque filter were adjusted. The torque filter was composed of the following secondary continuous filter, and the filter characteristics were determined while adjusting the parameters a _n1 , a _n2 , a _n3 , b _n1 , b _n2 , b _n3 .

  Then, K (s), L, V, A, D, and J were adjusted using the autonomous design device of Japanese Patent Application No. 2003-27880 under the conditions of the maximum number of individuals 20, the maximum number of generations 50, and the maximum number of trials 10 times. did. The transfer function to be controlled to be input to the simulator circuit unit 22 was set as follows.

Nak (s) / Dk (s) is a transfer characteristic from the motor current command to the table position when the controlled object has the kth friction characteristic.
Nmk (s) / Dk (s) is a transfer characteristic from the motor current command to the motor position when the controlled object has the kth friction characteristic.
Gbasek (s) is a transfer characteristic from the motor current command to the machine base acceleration when the controlled object has the kth friction characteristic.

  In this control object, a ball guide and a ball screw are used for the guide element and the power transmission mechanism, respectively, and the individual difference and the secular change of the frictional characteristics that they hold cause the system to fluctuate. The k-th friction characteristic indicates that the friction characteristics are defined by numbers when the friction characteristics are different in consideration of these circumstances.

  In addition, when the friction characteristic has a nonlinear characteristic, it is often difficult to express it by a transfer function. Therefore, in the simulator circuit unit 22, the friction characteristic can be expressed not only as a transfer function but also as a nonlinear function in which the friction force in the time response region is regarded as a kind of disturbance.

  In this embodiment, the friction fluctuation range of the control target is estimated by prior measurement, and the frictional force lookup table using the table speed as an input can express the dynamic friction characteristics of the upper limit, average and lower limit in the simulator circuit. Is inserted as shown in FIG.

An evaluation function with the following evaluation criteria is designed for the control target set this time. [Evaluation function 1]
If the positioning conditions (positioning time and positioning completion width) are not satisfied, a value obtained by multiplying the delay time and the weight value in the positioning deviation is added to the evaluation value.

[Evaluation function 2]
If the motor current command is relaxed, a large penalty is added to the evaluation value.
[Evaluation function 3]
A value obtained by multiplying the sum of the positioning deviation amounts after the completion of positioning by the weight value is added to the evaluation value.
[Evaluation function 4]
A value obtained by multiplying the weight value in the sum of absolute values of machine base residual vibration after positioning is added to the evaluation value.

Next, using the autonomous design apparatus according to the present invention, similarly, K (s), L, V, A, D, J, Cpos under the conditions of the maximum number of bodies 20, the maximum number of generations 50, and the maximum number of trials 10 times. (S) was optimized. At this time, Cpos (s) is calculated by the following equation.
Cpos (s) = {(Kd · s ² + Kp · s + Ki) / s} · T (s)
From this relationship, each coefficient of Kd, Kp, Ki and ΠTn (s) is incorporated as part of the chromosome information. The search range of each parameter of Cpos (s) is set so as to include each value of Cpos (s) designed initially.

  In the simulator circuit unit 22 shown in FIG. 6, all chromosome information is transmitted to the time response circuit unit 32, and only the parameters of the feedback compensator 26 are transmitted to the frequency response circuit unit 31. The simulator circuit unit 22 transmits the output results of the time response circuit unit 32 and the frequency response circuit unit 31 calculated using the parameters of the specific individual to the GA processing unit 21, and the GA processing unit 21 checks the fitness of the individual. The evaluation standard uses the following evaluation function for the output result of the frequency response circuit unit 31 in addition to the evaluation functions 1 to 4 when the feedforward compensator 25 and the position command are autonomously designed.

[Evaluation function 5]
In the round transfer function, a penalty is added to the evaluation value when the phase margin is less than 40 ° and the gain margin is less than 7 dB.
[Evaluation function 6]
In the complementary sensitivity function, a penalty is added to the evaluation value when the gain exceeds 3 dB.

The autonomous design results according to Japanese Patent Application No. 2003-27880 and the autonomous design results of the present invention are shown in FIGS.
In the autonomous design result of Japanese Patent Application No. 2003-27880, the target positioning time could not be achieved with respect to the controlled object whose dynamic friction characteristic is the lower limit. In addition, the residual deviation due to machine vibration after the positioning was completed resulted in the dynamic friction characteristics becoming slightly larger only for the control target with the upper limit.

  On the other hand, in the autonomous design result of the present invention, the target positioning time could be achieved for all the dynamic friction characteristics. Residual deviation due to machine vibration after positioning is complete is stable and does not depend on dynamic friction characteristics. Here, by using one of the frequency response characteristics stored in the frequency response circuit unit 31 in the autonomous design apparatus of the present invention, the position open loop characteristics of the feedback compensator initially designed and the feedback compensator designed autonomously. The results of comparing these are shown in FIGS. The frequency axis in each figure is normalized as a specific frequency f (Hz) and shown as a ratio to it.

  Although the compensator of the initial design of FIG. 11 has a phase margin of about 45 ° at the zero cross gain frequency, the autonomous design has only about 26 °. For this reason, the peak gain increased to about 7 dB with the complementary sensitivity function of FIG. However, it can be seen that the sensitivity characteristic of the low frequency before 0.2 f (Hz) is improved. From this result and positioning response waveform, the required phase margin is ensured within the range in which the stability of the feedback compensator 26 can be guaranteed in the two-degree-of-freedom control system in which the present invention is configured by the positioning control device and the actual positioning operation. However, it can be seen that it is possible to autonomously design a feedback compensator that promotes low sensitivity to prevent deterioration of positioning characteristics and machine vibration suppression effect.

  Further, it is obvious that the parameter group in the position control device including the feedback compensator can be adjusted by replacing the autonomous design device of the present invention with the embodiment after product shipment shown in Japanese Patent Application No. 2003-27880. is there.

  Needless to say, the scope of application of the present invention is not limited to the ball screw system, but can be implemented by applying the present invention to various positioning control devices using an electric motor as a drive source.

It is a conceptual diagram of the whole system explaining the outline | summary of this invention. 1 is a conceptual diagram of a ball screw system to which the present invention is applied. It is a flowchart which shows the flow of GA processing. It is a figure explaining the flow of the signal of the structure of a simulator circuit part, and a GA process part. It is a block diagram which shows the structural example of a positioning control apparatus. It is a figure explaining the structural example of the time response circuit part in the simulator circuit part in this invention. It is a figure explaining the structural example of the simulator circuit part by Japanese Patent Application No. 2003-27880. It is a flowchart explaining the process sequence in a time response circuit part. It is a figure which compares and shows the autonomous design result by Japanese Patent Application No. 2003-27880, and the autonomous design result of this invention (the 1). It is a figure which compares and shows the autonomous design result by Japanese Patent Application No. 2003-27880, and the autonomous design result of this invention (the 2). It is a figure which shows the measurement result of a position open loop characteristic about the feedback compensator designed initially and the feedback compensator designed autonomously. It is a figure which shows the measurement result of a complementary sensitivity function and a sensitivity characteristic about the feedback compensator designed initially and the feedback compensator designed autonomously. It is a flowchart explaining the autonomous design method of Japanese Patent Application No. 2003-27880. It is a flowchart explaining the autonomous design method of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Positioning control apparatus, 12 ... Position command production | generation part, 13 ... Position control part, 14 ... Parameter memory | storage part, 15 ... Machine stand, 16 ... Control object, 17 ... Electric motor, 18 ... Table (movable part), 19 ... Autonomous Design device, 20 ... ball screw, 21 ... GA processing unit, 22 ... simulator circuit unit, 23 ... machine vibration identification unit, 25 ... feed forward compensator, 26 ... feedback compensator, 31 ... frequency response circuit unit, 32 ... Time response circuit

Claims (7)

Autonomous motor control system that constitutes a positioning control system using position information on the rotational position of the motor or the position of the movable part of the device for a control target having vibration of a machine base equipped with a device driven by the motor In the design method,
For a specific moving distance or multiple moving distances of the movable part, (1) Satisfy the positioning specifications, (2) Consider the control target for machine vibration suppression, and (3) Consider operational safety (4) An autonomous design method for a motor control system, wherein a feedforward compensator, a feedback compensator, and a position command parameter that ensure the stability of the feedback compensator are autonomously designed using an optimization method.   The autonomous design method for an electric motor control system according to claim 1, wherein a genetic algorithm is used as the optimization method.   The simulator circuit unit used in the genetic algorithm includes a time response circuit unit for evaluating time response performance and a frequency response circuit unit for evaluating stability of the feedback compensator. An autonomous design method for an electric motor control system according to claim 2.   The frequency response circuit unit uses a frequency response data from a motor current value input command stored in advance to an observation amount position, and a feedback compensator defined by individual information, and a frequency response of a round transfer function. The autonomous design method for an electric motor control system according to claim 3, wherein the frequency response of the complementary sensitivity function is calculated.   An evaluation criterion that gives a penalty when the frequency response of the round transfer function calculated by the frequency response circuit unit falls below a target stability margin value, and the frequency response of the complementary sensitivity function calculated by the frequency response circuit unit An autonomous design method for an electric motor control system according to claim 3 or 4, wherein an evaluation function for feedback stability is set together with an evaluation criterion that gives a penalty when a target peak gain is exceeded. .   An evaluation standard that gives a penalty when the positioning specifications are not satisfied, an evaluation standard that gives a penalty when there is a risk of motion, and positioning performance and machine vibration suppression performance that satisfy the positioning specifications 6. The fitness of an individual is evaluated by adding together an evaluation function having an evaluation criterion that gives a penalty for a factor causing deterioration and the evaluation function of the feedback stability. An autonomous design method for an electric motor control system according to claim 1.   The search range of the parameter group that defines the feedback compensator stored in the chromosome is set so as to include the characteristics of the stabilizing compensator that is set initially or set after shipment. The autonomous design method of the electric motor control system in any one of thru | or 6.

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