JP3337826B2 - Open loop vibration suppression method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for suppressing vibration on the output side of a drive system having mechanical elasticity.

[0002]

2. Description of the Related Art Generally, a driving system includes an elastic body. Some elastic bodies have a simple shaft or beam, and others have a structure like a complicated speed reducer. The input side of the drive system has an electric drive motor, and the output side receives an inertial load or a load torque generated at a contact point of the environment. In such a drive system, when driving the motor,
Vibration occurs on the output side. Vibration is suppressed by appropriately controlling the motor.

[0003] There are two conventionally known vibration suppression methods. One is to feed back the position, speed, acceleration on the load side, or the amount of distortion or torque generated by the elastic body,
This is a method of suppressing vibration. Another method is to suppress vibration by an “open loop” method without performing such feedback.

In the latter open-loop system, there is known a method of estimating a vibration torque from an output of a disturbance observer added to a motor and suppressing the vibration by using the estimated vibration torque. The outline of this method is described below.

The disturbance torque estimated from the disturbance observer of the motor as shown in FIG. 1 is expressed by equation (1).

[0006]

(Equation 1)

Here, T _dis is a disturbance torque estimated by a disturbance observer. J _M and J _Mn are the inertia of the motor and its nominal value, respectively. D _M is the viscous drag coefficient, and K _T and K _Tn are the motor torque constant and its nominal value, respectively. T _F is the friction torque, ω _M is the rotation speed of the motor, and i _M is the current of the motor. T
_I is a vibration torque generated by the elastic body and acting on the motor. This torque is used for vibration suppression. This torque is obtained from equation (2) as follows.

[0008]

(Equation 2)

[0009] Of the terms on the right side of this equation except T _dis ,
All are unknown disturbance torques. In this state, the vibration torque cannot be estimated. All terms on the right must be known. For that purpose, the following method is adopted.

First, the parameters are set as shown in equation (3) by using catalog values of the motor or by identifying parameters. Thereby, the second term of the equation (2) becomes zero.

[0011]

[Equation 3]

Next, the friction torque T _F and the torque generated due to the viscous resistance D _M are measured in the entire rotation speed range of the motor, and the measured torque is expressed by the following equation (4).
Stored as a function T _ins of the rotational speed as shown in FIG.

[0013]

(Equation 4)

By substituting equation (4) into equation (2), equation (2) becomes the following equation (5).

[0015]

(Equation 5)

In equation (5), the torque (cogging torque) generated due to the fluctuation of the torque constant remains in an unknown state. Since the cogging torque is smaller than the vibration torque, it can usually be ignored. Therefore, the vibration torque can be estimated by the following equation (6).

[0017]

(Equation 6)

That is, the vibration torque is obtained by subtracting the measured disturbance torque from the torque estimated by the disturbance observer. The vibration torque thus estimated is used for the feedback of the motor to suppress the vibration.

[0019]

As described above, in the open-loop system in which the vibration torque is estimated from the output of the disturbance observer added to the motor and the vibration is suppressed by using the estimated vibration torque, identification of parameters is performed. , Friction torque and viscous drag torque must be measured. Therefore, when this method is adopted, considerable work is required. Further, the viscous resistance and friction fluctuate depending on the course of use and fluctuations in temperature. When these fluctuations occur, the measured disturbance differs from the actual disturbance, and a non-negligible error occurs in the estimation of the vibration torque. This error has an adverse effect on the accuracy of vibration suppression.

An object of the present invention is to avoid such a problem by measuring the viscous drag torque and the friction torque without measuring the viscous drag torque and the friction torque, based on the output of a disturbance observer added to the motor. An object of the present invention is to propose an open loop vibration suppression method capable of suppressing vibration.

[0021]

In order to solve the above-mentioned problems, in the present invention, vibration is suppressed without measuring viscous drag torque and friction torque as described below.

That is, in the vibration suppressing method of the present invention, the disturbance observer shown in FIG. 1 is used as it is. However, the feature of the present invention is that the frequency characteristics of the vibration torque are focused on.

The frequency of the vibration torque is 0 Hz (DC signal)
Consider that it will not be. The vibration torque always has a natural frequency of the vibration system or a frequency close to the natural frequency.
Generally, the disturbance torque shown in the equation (1) does not include the disturbance torque having the same frequency as the vibration torque. For example, the frequency of the friction torque is 0 Hz. The frequency of viscous drag torque is the same as the frequency of speed, and in general,
Has a low value. Therefore, these disturbance torques can be removed from the output of the observer using a high-pass filter. Conversely, if the frequency of the vibration torque is known, this torque can be extracted from the output of the observer by a bandpass filter.

Therefore, the vibration suppressing method of the present invention can be represented by the block configuration shown in FIG.

In this figure, G _F1 is a low-pass filter (generally (G _F1 = g / (s + g)), G _F2 is a band-pass or high-pass filter, and K _C is a gain for adjusting the vibration suppression effect.

[0026]

An equivalent current corresponding to the disturbance torque obtained from the disturbance observer of the motor is passed through a band-pass filter to obtain a vibration torque (current value) generated by the elastic body.
This current value (torque) is amplified by the gain K _C and subtracted from the motor current command (torque command). By this operation,
The control gain of the motor is reduced only at a frequency equal to the frequency of the vibration torque. The result appears as a vibration suppression effect on the output side (load side) of the drive system.

[0027]

EXAMPLE An experiment was conducted using a drive system combining an electric motor, a speed reducer, and an inertial load. The configuration shown in FIG. 2 was adopted as the vibration suppression control system. However, the filter G _F2 has a primary high-pass filter (G _F2 = s / (g2 + s), g ₂
= 1 Hz). The vibration suppression control gain Kc was set to 2. FIGS. 3 and 4 show the vibration suppressing effect at this time.

FIGS. 3A and 3B show frequency characteristics of the vibration system. FIG. 3A is a graph of a characteristic curve when the vibration suppression control of the present invention is not performed, and FIG. It is a graph of a characteristic curve when performing. FIG. 4 shows a step response of the driving system. FIG. 4A is a graph of a characteristic curve when the vibration is not suppressed according to the present invention, and FIG. 4B is a graph when the vibration is suppressed according to the present invention. 6 is a graph of a characteristic curve of FIG. As you can see from these figures,
It can be seen that by employing the method of the present invention, vibration on the output side of the drive system can be suppressed.

[0029]

As described above, according to the present invention, in an open-loop vibration suppression method for suppressing the vibration on the output side of a drive system including an elastic body by using the output of a disturbance observer attached thereto, By taking out the output of the observer through a filter that passes a predetermined frequency band, disturbance torque included in this output is removed, and an output corresponding to the vibration torque generated by the elastic body is obtained. The drive signal of the motor of the drive system is corrected based on the following. Therefore, according to the method of the present invention, the viscous drag torque and the friction torque are measured,
Unlike the conventional method of estimating the vibration torque based on these and suppressing the vibration, the measurement of the viscous drag torque and the friction torque is not required, so that a control system for suppressing the vibration can be realized without any trouble. . Also, since the vibration torque is not estimated based on the measured values of these torques,
It is also possible to avoid a problem that an error occurs in the estimation of the vibration torque due to the use environment or the like and the vibration cannot be appropriately suppressed.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram showing a conventional control system for suppressing open-loop vibration.

FIG. 2 is a schematic block diagram showing a control system for implementing a vibration suppression method according to the present invention.

FIG. 3 shows frequency characteristics of a vibration system, and (a)
6 is a graph of a characteristic curve when the vibration suppression control according to the present invention is not performed, and FIG. 6B is a graph of a characteristic curve when the vibration suppression control according to the present invention is performed.

FIG. 4 shows a step response of a driving system,
(A) is a graph of a characteristic curve when the vibration is not suppressed according to the present invention, and (b) is a graph of a characteristic curve when the vibration is suppressed according to the present invention.

[Explanation of symbols]

T _dis: disturbance torque estimated by a disturbance observer J _M: motor inertia J _Mn : nominal value of motor inertia D _M: viscous drag coefficient K _T: motor torque constant K _Tn・ ・ ・ Nominal value of motor torque constant _TF・ ・ ・ Friction torque ω _M・ ・ ・ Motor rotation speed i _M・ ・ ・ Motor current T _I・ ・ ・ Vibration generated by elastic body and acting on motor Torque G _F1 ··· Low pass filter G _F2 ··· Band pass (high pass filter) K _C · Gain for adjusting vibration suppression effect

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-5-100709 (JP, A) JP-A-2-111278 (JP, A) JP-A-6-318115 (JP, A) 53603 (JP, A) JP-A-5-168267 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02P 5/00 F16F 15/18 G05B 11/36

Claims (1)

(57) [Claims] 1. The vibration on the output side of a drive system including an elastic body,
In the open-loop vibration suppression method of suppressing the output of the disturbance observer attached thereto, the disturbance torque contained in the output of the disturbance observer is extracted by extracting the output of the disturbance observer through a filter that passes a predetermined frequency band. An open-loop vibration suppression method comprising: removing an output corresponding to a vibration torque generated by an elastic body; and correcting a drive signal of a motor of a drive system based on the output.