JPH08278821A - Damping method for servo control system - Google Patents

Abstract

PURPOSE: To provide the damping method of a servo control system capable of damping the system without providing a mechanical detector for detecting the acceleration of an arm on the side of the arm. CONSTITUTION: In the servo control system 10, the rotational angular velocity θm' of the driving shaft of a motor 3 is detected by an originally provided velocity detector 6. In the meantime, the rotational angular acceleration θa"Λ of the arm 1 is estimated from the rotational angular acceleration θm" obtained by a differentiator 9 based on the rotxational angular velocity θm' by an acceleration estimation device 7. The rotational angular acceleration θa"Λ of the arm 1 is fed back to the control command amount side of the motor 3, phase inversion is performed and the system is clamped. Thus, the need of providing the mechanical detector for detecting the rotational angular acceleration of the arm 1 is eliminated and the constitution of the arm 1 is simplified.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention returns the acceleration of a driven part such as a robot arm operated by a drive part such as a servomotor to the control command amount of the drive part.
The present invention relates to a vibration control method for suppressing vibration of a servo control system including the drive section and the driven section, and more particularly to a vibration control method for a servo control system having a simple mechanical structure.

[0002]

2. Description of the Related Art Generally, most industrial robots have a cantilever structure in which the mechanism is unstable, that is, the ends of arms are free ends. Further, between the motor and the arm of the robot, there is a power transmission mechanism having elasticity such as a speed reducer. In addition, the natural frequency of the mechanical system of the robot is often low. Therefore, when a large acceleration / deceleration is generated in the arm during the operation of the robot, vibration is excited at the natural frequency of the above mechanical system and residual vibration is likely to remain, which may cause a functional problem, especially between the arm and the motor. This problem becomes noticeable when the power transmission mechanism between them undergoes elastic deformation. Further, not only the robot as described above, but also a system in which a driven part as an inertial load is driven by a driving part such as a motor through a power transmission mechanism in which elastic deformation cannot be ignored causes a similar vibration problem. . With respect to such vibration, the technique disclosed in Japanese Examined Patent Publication No. 2-33169 provides each detector for detecting its displacement, speed, or acceleration on the inertial load side, and detects the acceleration or the like on the inertial load side. Is fed back to the control command amount on the side of the drive unit. At this time, for example, the fed back acceleration signal is adjusted to have a phase opposite to the AC component of the velocity of the inertial load. There is. Thereby, the vibration of the mechanical system is suppressed.

Servo control system almost equivalent to the technology disclosed above
Is shown in FIG. Servo control system 10 shown in FIG._dThen,
The structure of a general speed control type servo motor driver 11
Similarly, the rotation angular velocity θ_mDetect ′_,example
If a speed detector 6 consisting of a tacho generator etc. is provided
ing. Also, the arm 1 side as an inertial load has an arm
Rotational angular acceleration of 1_aIs provided with a detector 8 for detecting
ing. The rotational angular acceleration θ of the arm 1 detected above_a″
Is the rotational angular velocity of the motor 3 detected by the speed detector 6.
Input of the speed controller after being corrected by a signal based on degrees
The target value of the rotational angular velocity of the motor 3 is supplemented by being fed back to
To compensate. Therefore, the servo control system 10_dThen, speed check
Rotational angular velocity θ of the motor 3 detected by the output device 6_m'But
Predetermined target value of rotational angular velocity θ_dTo become '
_,Target value of rotational angular velocity with the rotational speed manipulated variable compensated above
Is calculated by the speed controller based on And this
Based on the rotational angular velocity operation amount, the torque as the control command amount
Torque T is calculated by the torque controller and input to the motor 3.
It At this time, the speed controller may operate, for example, after the compensation.
The signal related to the target value of the rotational angular velocity of the motor 3
Adjust so that the phase is opposite to the AC component of the angular velocity,
It is used for calculation of the torque T. Thus, as mentioned above
Vibration of the mechanical system is suppressed. Below, on the right shoulder of each code
The attached ‘(dash) is the first-order time
The minute value, ″ (2 dashes) is the second-order time derivative, ^ (ha
Indicates the estimated value.

[0004]

By the way, according to the conventional technique disclosed above, it is necessary to mount a mechanical detector 8 for detecting the rotational angular acceleration on the arm side of the robot. However, since the space inside the arm of the robot is generally small, it is preferable to reduce the number of parts to be incorporated as much as possible. Also, the detector 8
There is also a problem in that the electrical wiring between the motor side and the motor side becomes complicated when it is mounted in the arm. Therefore, an object of the present invention is to provide a damping method for a servo control system capable of damping the system without providing a mechanical detector for detecting the acceleration of the driven part on the driven part. That is.

[0005]

In order to achieve the above-mentioned object, the main means adopted by the present invention is the gist of the invention, in which the acceleration of a driven part operated by a drive part is controlled to the drive part. In a vibration damping method for suppressing vibration of a servo control system including the drive unit and the driven unit by returning to the command amount, at least a control command amount to the drive unit and an operation amount from the drive unit. , The relationship for obtaining the acceleration of the driven part from the inertia of the driving part and the inertia of the driven part is set in advance, and the setting is made from the control command amount to the driving part and the operation amount from the driving part. It is configured as a vibration control method for a servo control system, which is characterized in that the acceleration of the driven part is calculated based on the relationship thus established.

[0006]

In the damping method of the servo control system according to the present invention, at least the control command amount to the drive unit for operating the driven unit, the operation amount from the drive unit, the inertia of the drive unit, the driven unit. The relationship for obtaining the acceleration of the driven part from the inertia of the above and the inertia of the driven part is set in advance. Then, the acceleration of the driven portion is calculated from the control command amount to the driving portion and the operation amount from the driving portion based on the preset relationship. Therefore, the driven part does not need a mechanical detector for detecting the acceleration of the driven part, and the structure of the driven part becomes extremely simple.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the present invention will be described below with reference to the accompanying drawings for the understanding of the present invention. The following embodiments are examples of embodying the present invention and are not intended to limit the technical scope of the present invention. FIG. 1 is a schematic diagram showing a robot used for applying a vibration control method of a servo control system according to an embodiment of the present invention, and FIG. 2 controls the operation of an arm while suppressing the vibration of the robot. 3 is a block diagram showing the configuration of a servo control system according to another embodiment of the present invention. FIG. 3 is a block diagram showing the configuration of a servo control system for estimating arm acceleration using an observer circuit and a differentiator according to another embodiment of the present invention. 3 is a block diagram showing a modified example of the servo control system shown in FIG. 3, and FIG. 5 is a block diagram showing another modified example of the servo control system shown in FIG. However, the same reference numerals are used for the same elements as those of the conventional servo control system 10 _d shown in FIG. 6, and the detailed description thereof will be omitted.

In a mechanical system such as a robot to which the servo control system of the present invention is applied, as shown in FIG. 1, a motor 3 mechanically interacts with an arm 1 via a speed reducer 2 as a power transmission mechanism having elasticity. The arm 1 is connected to drive the arm 1 in rotation. The motor 3 is controlled by the servo control system 10 of this embodiment shown in FIG. The portion surrounded by the broken line in FIG. 2 has a configuration equivalent to that of a general speed control type servo motor driver 11. In this configuration, it is assumed that the current minor loop has a sufficiently fast response and the motor 3 outputs a torque according to the control command value (torque T). The motor 3 originally has a speed detector 6 for detecting the rotational angular speed θ _m ′. The servo control system 10 is connected to the servo control system 10 _d.
The basic structure is substantially the same as that of the conventional servo control system 10 _d, and the difference from the conventional servo control system 10 _d is that a mechanical detector 8 (FIG. 6) for detecting the rotational angular acceleration θ _a ″ of the arm 1 (an example of a driven part). ) Is omitted. Instead of the detector 8, torque T to the motor 3, rotational angular acceleration θ _m ″ from the motor 3 (an example of operation amount), and an inertia moment I of the motor 3 are used. _{Based on m} (inertia), the inertia moment I _{a of the} arm 1 (inertia; drive shaft conversion value of the motor 3), and the reduction ratio N between the motor 3 side of the reduction gear 2 and the arm 1 side, the rotation of the arm 1 is performed. That is, the differentiator 9 and the acceleration estimator 7 for calculating the angular acceleration θ _a ″ ^ are provided.

By the way, assuming that the damping rate of vibration of the mechanical system of the robot shown in FIG. 1 is very small, and ignoring this damping rate, the equation of motion of the mechanical system is derived as follows. . I _a θ _a ″ + K {θ _a − (θ _m / N)} = T (1) I _m θ _m ″ + K {(θ _m / N) −θ _a } = 0 (2) Where I _a : moment of inertia of arm 1 (inertia: converted value of motor 3 drive axis) I _m : moment of inertia of motor 3 (inertia) θ _a : rotation angle of arm 1 (converted value of motor 3 drive axis) θ _m : Rotation angle of the motor 3 K: Spring constant of the speed reducer 2 (rotation axis conversion value of the motor 3) N: Reduction ratio of the speed reducer 2 T: Torque to the motor 3.

In the above structure, the rotational angular velocity θ _m ′ of the motor 3 can be detected by the velocity detector 6 which is conventionally provided. On the other hand, according to the mechanism of this embodiment, the rotation angle θ _a or the rotation angular velocity θ required to obtain the rotation angular acceleration of the arm 1 on the downstream side of the speed reducer 2 in the power transmission direction.
Since _a 'is not provided with a mechanical detector for detecting _these, can not be actually _detected, it is deformed from the equation of motion represented by the above formula (1) and (2) The rotational angular acceleration of the arm 1 can be obtained from the following equation (3). θ _a ″ ^ = N (T−I _m θ _m ″) / I _a (3) where θ _a ″ ^ is the estimated rotational angular acceleration of the arm 1. The above (1) The relationships shown in equations (3) are:
As a model formula, each is preset and stored as a program in a memory (not shown) of the acceleration estimator 7.

Therefore, in the servo control system 10,
The motor 3 is driven by the torque T (an example of the control command amount) from the torque controller, and the rotational angular velocity θ _m ′ of the drive shaft is driven.
Is detected by the speed detector 6. The rotational angular velocity θ _m ′ is differentiated by the differentiator 9 to obtain the rotational angular acceleration θ _m ″.
Is input to the acceleration estimator 7. On the other hand, the torque T from the torque controller is also input to the acceleration estimator 7. Therefore, the acceleration estimator 7 uses the input torque T
And the rotational angular acceleration θ _m ″ are applied to the relationship of the equation (3) to estimate the rotational angular acceleration θ _a ″ ^ of the arm 1. The estimated rotational angular acceleration θ _a ″ of the arm 1 is corrected by a signal based on the rotational angular velocity θ _m ′ of the motor 3 and then fed back to the target value θ _d ′ of the motor 3. The corrected arm 1
The target value of the rotational angular velocity of the motor 3, which is compensated by the rotational angular acceleration of, is input to the velocity controller, and the arm 1
Is adjusted to have a phase opposite to that of the AC component of the rotational angular velocity, and is used for calculation of the torque T. As a result, vibration of the mechanical system of the robot is suppressed. That is, according to the servo control system 10 to which the method of the present embodiment is applied, it is not necessary to provide a mechanical detector for actually detecting the rotational angular acceleration of the arm 1 which is the driven part, and the above-mentioned method is adopted. The rotational angular acceleration of the arm 1 can be estimated by the calculation in the differentiator and acceleration estimator 7, and the vibration of the mechanical system can be suppressed by using the estimated rotational angular acceleration. Therefore, the arm 1
The internal structure can be simplified.

By the way, in the industrial robot,
Moment of inertia of arm 1 (inertial load)
I_aMay change significantly. In such cases,
Rotation of the arm 1 estimated from equation (3)
Angular acceleration θ_aIt means that the gain of ″ ^ changes.
Therefore, the rotational angular acceleration θ_aFor "" feedback
Of the amplifier on the downstream side of the acceleration estimator 7 corresponding to the gain of
By making the IN variable according to the posture of the robot,
As described above, the moment of inertia I of the arm 1_aChanges
It is possible to obtain the damping effect for the mechanical system that
It still_,In the above-mentioned embodiment, it is detected by the speed detector 6.
Rotational angular velocity θ of the motor 3 _m′ Is differentiated by differentiator 9
The rotational angular acceleration θ of the motor 3_mFor ″
However, the rotation angle of the drive shaft of the motor 3 is not limited to this.
Is detected directly using, for example, an encoder,
Rotation angle θ_mThe second-order differentiation of the value of
Rotational angular acceleration of the motor 3_m″ May be calculated.

On the other hand, FIG. 3 shows _a servo control system 10a according to another embodiment of the present invention. In the servo control system 10 _a , in place of the mechanical detector 8 (see FIG. 6) on the arm 1 side provided in the conventional servo control system 10 _a , in particular,
A rotation angle θ _m of the motor 3 from the position detector 5 provided on the motor 3 side (an example of an operation amount), a rotation angular velocity θ _m ′ of the motor 3 from the speed detector 6 (an example of an operation amount), and Based on the target value θ _t (an example of the control command amount) of the rotation angle set and input to control the rotation angle θ _m of the motor 3, the rotation angle θ _a ^ and the rotation angular velocity θ _a ′ of the arm 1 are set. The observer circuit 12 for estimating ^ and the rotational angular acceleration θ from the estimated rotational angular velocity θ _a ′ ^ of the arm 1 above.
A differentiator 13 for calculating _a ″ is provided. However, although the rotation angle θ _a ^ of the arm 1 can be estimated by the observer circuit 12, this embodiment has almost no relation to this embodiment, so the description will be given. Not shown in FIGS. 3-5 for simplicity.

The observer circuit 12 is a well-known state observer, and is a control command amount (control input) of the motor 3 (driving unit) and an operation amount (control output) from the motor 3 (driving unit).
Has a function of estimating an unmeasurable state variable (for example, the rotation angle and the rotation angular velocity of the arm 1 here), and determines the number of control inputs input to the observer circuit 12 and The number of control outputs determines the order of the coefficient matrix used in the state observation formula modified based on the formula (3). As the parameters forming the coefficient matrix, a certain degree of accurate value capable of accurately estimating the rotation angle and the rotation angular velocity of the arm 1 is obtained and set by a general parameter identification method based on a large number of experimental results. Has been done. Therefore, according to the servo control system 10 _a , the rotational angular acceleration θ _a ″ ^ of the arm 1 can be estimated relatively accurately by the calculation in the observer circuit 12 and the differentiator 13. The rotational angular acceleration θ _a ″ ^ is added to the rotational angular velocity of the motor 3 output from the speed detector 6 via the amplifier (gain = K2), and then fed back to the target value θ _t of the rotational angle of the motor 3. Is used for damping the above mechanical system. Thereby, also in the servo control system 10 _a, in suppressing vibration of the mechanical system, it is not necessary to provide a mechanical detector for detecting a rotation angular acceleration of the arm 1. Therefore, the internal structure of the arm 1 can be simplified.

The servo control system 10 described in the above embodiment is used.
Since the acceleration estimator 7 has a small calculation order (see FIG. 2), it has the advantage that only a small calculation capacity is required, but it does not have a function of cutting high frequency noise. On the other hand, the observer circuit 12, which is a state estimator, generally uses many filters,
It has the function of cutting high frequency noise. Therefore, the servo control system 10 _a of the observer circuit 12 and differentiator 13 may require a large computation capacity than the differentiator 9 and acceleration estimator 7 of the servo control system 10,
The rotational angular acceleration θ _a ″ ^ of the arm 1 can be obtained with high estimation accuracy by cutting off high-frequency noise.
On the other hand, when the speed detector 6 for detecting the rotational angular speed θ _m ′ is not provided on the motor 3 side _{, the} differentiator 14 is provided like the servo control system 10 _b shown in FIG. The rotation angle θ of the motor 3 from the position detector 5
The rotation angular velocity theta _m 'obtained by differentiating the _m, it is also possible to input the observer circuit 12.

[0016] Further, even in a configuration in which omitted the speed detector 6 and the differentiator 14, the servo control system 10 _c shown in FIG. 5
As in, based on the rotational angle theta _m and the target value theta _t of the motor 3 is _input, the rotational angle of the arm 1 θ _a "^ and the rotational angular velocity theta _a '^ the rotation angular velocity of the motor 3 from the group theta
By using the observer circuit 12 _a that can also estimate _m ′ ^, it is possible to suppress the vibration of the mechanical system without providing a detector for mechanically detecting the rotational angular acceleration of the arm 1 on the arm 1 side. it can. In this case, the state observation formula and the coefficient matrix are rearranged so that the rotational angular velocity of the motor 3 can be treated as an unmeasurable state variable.

[0017]

According to the present invention, by returning the acceleration of the driven portion operated by the driving portion to the control command amount to the driving portion, a servo including the driving portion and the driven portion is provided. In a vibration damping method for suppressing vibration of a control system, at least a control command amount to the drive unit, an operation amount from the drive unit, an inertia of the drive unit and an acceleration of the driven unit from the inertia of the driven unit. The relationship to be obtained is set in advance, and the acceleration of the driven part is calculated from the control command amount to the drive part and the operation amount from the drive part based on the set relationship. A damping method for a servo control system is provided. Thereby,
Since the acceleration of the specific drive unit is obtained by calculation, it is not necessary to provide a mechanical detector for detecting the acceleration of the driven unit on the driven unit when damping the servo control system. Therefore, the configuration of the driven portion can be extremely simplified.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a robot used for applying a vibration suppression method for a servo control system according to an embodiment of the present invention.

FIG. 2 is a block diagram showing the configuration of a servo control system that controls the operation of the arm while suppressing the vibration of the robot.

FIG. 3 is a block diagram showing the configuration of a servo control system that estimates an arm acceleration by using an observer circuit and a differentiator according to another embodiment of the present invention.

FIG. 4 is a block diagram showing a modified example of the servo control system of FIG.

5 is a block diagram showing another modification of the servo control system of FIG.

FIG. 6 is a block diagram showing a configuration of a conventional servo control system as an example of the background of the present invention.

[Explanation of symbols]

1 ... arm (driven portion) 3 ... motor (drive unit) 7 ... acceleration estimator 9 ... differentiator _{10,10 a, 10 b, 10 c} , 10 d ... servo control system 12, 12 _a ... observer circuit 13 ... estimate I _m ... motor differentiator T ... torque (control instruction amount) theta _t ... position command value (control command amount) theta _m "... rotational angular acceleration theta _a drive shaft of the motor" ^ ... rotational angular acceleration of the arm Moment of inertia (inertia) I _a ... Arm inertia moment (inertia)

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G05D 3/00 G05D 3/00 X 13/62 13/62 E 19/02 19/02 D

Claims (3)

[Claims] 1. The vibration of a servo control system including the driving unit and the driven unit is suppressed by returning the acceleration of the driven unit operated by the driving unit to the control command amount to the driving unit. In the vibration damping method described above, a relationship for obtaining the acceleration of the driven part from at least the control command amount to the driving part, the operation amount from the driving part, the inertia of the driving part and the inertia of the driven part is preset. The acceleration of the driven part is calculated from the control command amount to the drive part and the operation amount from the drive part on the basis of the set relationship. Method. 2. The relationship for obtaining the acceleration of the drive unit is represented by a model formula for calculating the acceleration of the drive unit from the control command amount to the drive unit and the operation amount from the drive unit. 1. The vibration control method for the servo control system according to 1. 3. The relationship for obtaining the acceleration of the drive unit is expressed by a state observation formula for calculating the acceleration of the drive unit from the control command amount to the drive unit and the operation amount from the drive unit. The vibration control method for a servo control system according to Item 1.