JPH0417591A - Servo control circuit - Google Patents

Abstract

PURPOSE:To control influence of vibration and friction by performing compensation for taking out only elastic vibration constituents by reducing a twisting amount needed for acceleration/deceleration from an estimated swing angle which is obtained by an estimator and that for coping with friction and then feeding back this estimated twisting angle compensation value and an estimated friction to the estimator. CONSTITUTION:Friction and twisting angle of a spindle are estimated independently from an estimator 4 by using a model which includes friction and twisting rigidity of the spindle. Then, a twisting amount needed for acceleration/ deceleration and that corresponding to friction are subtracted from an estimated twisting angle Q' which is obtained from this estimator 4 for performing compensation for taking out only an elastic vibration constituent and this estimated twisting angle compensation value theta and an estimated friction tau'L are fed back to the estimator 4.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a servo control device applied to machines such as low-rigidity machine tools and robots in which friction and torsion of a transmission shaft cannot be ignored.

[Prior Art] Fig. 4 shows a conventional servo control device that is applied to low-rigidity machines such as machine tools and robots where friction and torsion of the transmission shaft cannot be ignored.

In the figure, 1 is a controlled object, 2 is a control device that executes control of the controlled object 1, and 3 is a command value generation section that gives a command value to the control device 2.

In the control device 2, 7 is a position gain generation section, and 8 is a speed gain generation section. Friction estimator 12 for rigid body model that does not consider
The estimated torque τ is obtained by adding the outputs from the controller 10, and the estimated torque τ is applied to the controlled object 1, and is fed back to the friction estimator 12 in order to suppress the influence of friction.

[Problem to be solved by the invention] In the conventional servo control device described above, when friction is estimated using the rigid body model friction estimator 12 for the controlled object 1 with low rigidity, the elastic vibration component of the controlled object 1 becomes the estimated torque. The estimated torque τ itself oscillates. Furthermore, there is a drawback in that the vibration is further increased by feeding back this estimated torque τ.

The present invention has been made in view of the above circumstances, and its purpose is to provide a servo control device that can reliably suppress vibrations and suppress the effects of friction. be.

[Means and effects for solving the problem] In other words, the present invention uses a model including friction and torsional stiffness of the shaft to independently estimate friction and the torsional angle of the shaft by an estimator, and The estimated torsion angle is corrected by subtracting the torsion required for acceleration/deceleration and the torsion to accommodate friction from the obtained estimated torsion angle to extract only the elastic vibration component. This system is designed to provide feedback to the user, thereby reliably suppressing vibrations and the effects of friction.

[Embodiment] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

Figure 1 shows the system configuration.

The basic configuration is the same as shown in Figure 4, so
Identical parts are given the same reference numerals and their explanations will be omitted.

Now, the angle θm and angular velocity ωm of the motor detected from the controlled object 1 are input to the control device 22.

This control device 22 also receives a position command θr, a speed command ωr, and an acceleration command (nr) from the command value generation section 3, and a control torque τ is outputted from the control device 22 and sent to the control device 1. Ru.

Inside the control device 22, the motor angular velocity ωm input from the controlled object 1 and the control torque τ which is the output of the main control device 22 are input to the friction torsion angle estimator 4. The friction torsion angle estimator 4 is configured to be a friction torsion angle estimator shown by 11 in FIG. 2 for the model of the controlled object shown by 10 in FIG. A friction torque of 7L is output.

The speed command ωr input from the command value generation unit 3 is sent to the friction correction unit 5 in the control device 22, where the speed command ωr is
A friction correction torsion angle ΔθF corresponding to the positive or negative sign of is calculated.

On the other hand, the acceleration command Ir input from the command value generation section 3 is also sent to the acceleration/deceleration correction gain generation section 6 within the control device 22.
Here, the acceleration/deceleration correction torsion angle ΔθACC is calculated.

Then, from the estimated torsion angle Δθ output from the friction torsion angle estimator 4, the friction correction torsion angle Δθ2 output from the friction correction unit 5 and the acceleration/deceleration correction output from the acceleration/deceleration correction gain generation unit 6 are calculated. The torsion angle ΔθACC is subtracted, and the subtraction result of the table becomes the torsion angle correction value Δi* and is given to the torsion angle feedback gain generation section 9.

The deviation of the position command θr from the command value generation unit 3 from the motor angle θm input from the controlled object 1 is calculated in the control device 22, and the deviation is amplified by the position gain generation unit (Gp) 7. The speed command ωr is further added to the output of the position gain generation unit 7, and the motor angular velocity ωm input from the controlled object 1 is subtracted, and then the speed gain generation unit (
Gy) is amplified at 8. The acceleration command ωr input from the command value generation unit 3 is added to the output of the velocity gain generation unit 8, while the torsion angle feedback gain from the torsion angle feedback gain generation unit 9 inputting the estimated torsion angle correction value Δθ is subtracted. Furthermore, the friction torsion angle estimator 4
The estimated friction 7L outputted by is added as feedback to become the control torque τ. This control torque τ drives the controlled object 1 as an output of the control device 22.

The following describes the effects of estimating the friction and torsion angle, correcting the estimated torsion angle, and feedback of the estimated torsion angle correction value and the estimated friction in the above configuration.

First, we will show the operation of the estimator 4 that estimates friction and torsion angle independently.

Figure 3 shows the basic concept of a mechanical system with low rigidity and friction, where the equations of motion are the following equations (1) and (2).
It is expressed by the formula. Here, input torque is τ, friction is τ1,
The moments of inertia of the motor and load are Jm, JL, respectively.
When the torsional stiffness and torsional viscosity of the shaft are respectively KR and DR, the only variable that can be used is ωm in the equation, so the output equation is the following equation (4). In other words, (however, it becomes.In this case, the state variable is (however,).If the above equations (1) and (2) are transformed and expressed as a state equation, the following equation (3) is obtained.Also, the observation and It is what it is.

Considering the above equations (3) and (4) for controlled object 1, the state variable Z is the estimated value of the state variable The equation is as follows. In other words, (where,
From the motor angular speed ωm and the input torque τ, the output deviation between the controlled object 1 and the estimator model is ``ωm - ωm''.
and is fed back to the estimator model using gain pressure, Z = (A −E C) Z 1E ωm + B
T =・(7), and if the eigenvalue of rA-ECJ in this formula is appropriately determined and the gain pressure is designed, "X-Z
Since J converges to "0", the state Z of the estimator 4 estimates the state X of the controlled object 1. The state of this estimator 4 can be

Next, the operation of correcting the estimated twist angle will be explained.

If the estimated torsion angle 0 is fed back to the estimator 4 as it is, the responsiveness of the entire system will deteriorate because the torsion required for acceleration/deceleration and the torsion to cope with friction will be suppressed. Therefore, from the estimated torsion angle Δθ, the torsion necessary for acceleration/deceleration and the torsion Δθ1 to cope with friction are calculated. Correction is performed by subtracting ΔθACC and extracting only the obtained elastic vibration component Δθ.

Finally, the estimated torsion angle correction value and the estimated friction τ are added together to obtain the control torque τ, which is applied to the controlled object 1 and also fed back to the estimator 4, thereby suppressing vibration and suppressing the influence of friction. The control to be performed will actually be executed.

[Effects of the Invention] As detailed above, according to the present invention, friction and the torsional angle of the shaft are independently estimated by an estimator using a model including friction and torsional stiffness of the shaft, and this estimator The estimated torsion angle is corrected by subtracting the torsion required for acceleration/deceleration and the torsion to accommodate friction from the obtained estimated torsion angle to extract only the elastic vibration component. Since the torque is fed back to the control target, it is possible to provide a servo control device that can suppress vibrations in the torque applied to the controlled object and suppress the influence of friction.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the system configuration of an embodiment of the present invention, Fig. 2 is a diagram showing details of the friction/torsion angle estimator and the model of the controlled object shown in Fig. A diagram showing the basic concept of a mechanical system having friction, and FIG. 4 is a block diagram showing a conventional servo control device. 1... Controlled object, 2, 22... Control device, 3...
Command value generation unit, 4...Friction/torsion angle estimator, 5...
・Friction correction section, 6... Acceleration/deceleration correction gain generation section,
7... Position gain generation section, 8... Velocity gain generation section, 9... Torsion angle feedback gain generation section, 10
... Controlled object model, 11... Friction/torsion angle estimator model, 12... Friction estimator using rigid body model. Applicant's agent Patent attorney Takehiko Suzue

Claims (1)

[Claims] An estimator that independently estimates the friction of a mechanical shaft to be controlled and the torsion angle of the shaft, and a method for dealing with the torsion and friction necessary for acceleration/deceleration from the torsion angle estimated by the estimator. and a feedback path for feeding back the estimated torsion angle correction value obtained by the correction means and the estimated friction obtained by the estimator. A servo control device characterized by: