JPH09282008A - Servo controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a servo controller which can highly precisely and easily execute positioning for a machine system having a structure with large friction. SOLUTION: The controller is constituted by using a disturbance estimation observer 12 for estimating adisturbance element operating on a load as equivalent disturbance. In such a case, a disturbance coiuntermeasure generation part 13 is provided and pulse-like compensation torque for dissolving the influence of disturbance whose change is fast is outputted before a position deviation occurs owing to the estimation delay of the observer 12 when the disturbance of fast change such as friction is added to the load.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disturbance used for positioning a mechanical system having a structure with large friction, such as an arm of an assembling robot used in production equipment, at high speed and with high accuracy. The present invention relates to a servo control device using an estimation observer.

[0002]

2. Description of the Related Art Conventionally, as a technique relating to a servo control device using this type of disturbance estimation observer, there are those disclosed in, for example, JP-A-2-10411 and JP-A-6-35506. This Japanese Patent Laid-Open No. 2-1041
The actuator control device according to Japanese Unexamined Patent Publication No. 1 discloses a combination of an actuator having a force constant or a torque constant of Kt and a load that applies a load force of T _ext or a load torque to the actuator, and an inertial force in terms of the center of gravity or The moment of inertia converted to the rotation axis is J, the viscous friction force converted to the center of gravity position or the viscous friction torque converted to the rotation axis is Dω, and the Coulomb friction force converted to the center of gravity position or the coulomb converted to the rotation axis. When the friction torque becomes F, in the actuator control device that controls the output of the actuator according to the control amount Ia of the actuator, a disturbance given by a predetermined formula from the velocity component ω or the acceleration component ωs of the actuator. seeking force or disturbance torque T _dis, the actuator compensation control amount corresponding thereto It is obtained by configured with feedback means for feeding back.

As described above, the actuator control apparatus according to Japanese Patent Laid-Open No. 2-10411 estimates the disturbance force or the disturbance torque T _dis based on a predetermined equation, and the compensation control corresponding to the estimated value of this observer. The amount is fed back to the actuator to be controlled, but in order to ensure the stability of operation and to remove noise and the like,
The estimated value of the observer is fed back via a low pass filter.

Further, in the variable structure control method according to the above-mentioned Japanese Patent Laid-Open No. 6-35506, the stabilizing compensating means consisting of P (proportional) and I (integral) for the deviation amount between the command input of the controlled object and the state amount. And the applied input amount of the controlled object is calculated via the first-order lag filter using the applied input amount and the state amount of the controlled object. In the motor controller having the equivalent disturbance compensating means described above, P (proportional) and I
A constant such as (integration) and the time constant of the first-order lag filter are configured to be variable in accordance with the operating condition by multiplying the deviation amount or its integral value by a weighting coefficient and adding them.

As described above, the variable structure control method according to Japanese Patent Laid-Open No. 6-35506 discloses the speed and speed provided outside the disturbance estimation observer for the purpose of improving responsiveness and ensuring stability during high-speed movement. The position loop gain is set as a function of velocity deviation or position deviation, and the variable structure is configured to increase the gain in the area where the deviation becomes large and decrease the gain in the area where the deviation becomes small. .

[0006]

However, the prior art described above has the following problems. That is, the actuator control device according to Japanese Unexamined Patent Publication No. 2-10411 described above feeds back the estimated value of the observer through a low-pass filter in order to ensure stability of operation and to remove noise and the like. There is. Therefore, in the above actuator control device, when the cutoff frequency of the low-pass filter is low, a delay occurs in feeding back the estimated value of the disturbance observer,
However, there is a problem in that there is a portion that cannot be completely dealt with by a disturbance such as friction that changes instantaneously in proportion to the speed.

In order to solve such a problem, the cutoff frequency of the primary low-pass filter is increased,
A method of increasing the order is conceivable, but if the cutoff frequency of the low-pass filter is increased, the operation becomes unstable, and if the order is increased, there is a problem of hardware calculation ability. Therefore, use an expensive CPU. It is necessary to increase the cost, which causes a new problem of increasing cost.

On the other hand, in the case of the variable structure control method according to the above-mentioned Japanese Laid-Open Patent Publication No. 6-35506, when a mechanical system having a large friction is positioned at a high speed, an area where a deviation amount is small, in which an influence of a static friction force becomes particularly large, There is a problem that it takes a long time for the compensating force to overcome the frictional force during the movement in, and as a result, the settling time is extended and high-speed positioning cannot be performed.

Further, in the case of the variable structure control method according to the above-mentioned Japanese Patent Laid-Open No. 6-35506, when the velocity deviation or the position deviation is simply used as a reference of the variable condition, the influence of static friction becomes particularly large at the time of rising of the velocity. In order to increase the gain during settling and suppress the vibration, rather than follow-up performance, to operate stably, when you want to lower the gain when moving at a constant speed at high speed, complicated condition settings are required. There is also a problem that it becomes difficult to make a sensory adjustment according to the movement of the.

Therefore, the present invention has been made to solve the above-mentioned problems of the prior art, and its object is to provide a mechanical system having a large frictional structure.
An object of the present invention is to provide a servo control device capable of easily realizing high-speed and highly accurate positioning.

[0011]

That is, a servo control device according to a first aspect of the present invention is a servo control device using a disturbance estimation observer for estimating a disturbance element acting on a load as an equivalent disturbance. , When a disturbance with a fast change such as friction is applied to the load, before the position deviation occurs due to the estimated delay of the observer, a disturbance resistance force that outputs a pulse-shaped compensating torque to cancel the influence of the fast change with the disturbance. It is configured to have a generating portion.

According to a second aspect of the present invention, there is provided a servo control device using a disturbance estimation observer for estimating a disturbance element acting on a load as an equivalent disturbance. It is configured to have a gain changing unit that changes the loop gains of the speed and the position by using the difference between the integrated value of 1 and the actually detected position signal of the load.

Further, the servo control device according to the third aspect of the present invention is a servo control device using a disturbance estimating observer for estimating a disturbance element acting on a load as an equivalent disturbance. When a disturbance with a fast change is added, before the position deviation occurs due to the estimated delay of the observer, a disturbance resistance generating unit that outputs a pulse-shaped compensating torque for canceling the influence of the disturbance with a fast change, and the load It is configured to have a gain varying unit that varies the loop gains of the speed and the position by using the difference between the integrated value of the commanded speed with respect to and the actually detected position signal of the load.

In the servo control device according to the first aspect of the present invention, when a disturbance such as a friction that changes rapidly is applied to the load, the change is rapid before the position deviation occurs due to the estimation delay of the observer. Since it is configured to have a disturbance counter force generation unit that outputs a pulsed compensation torque to cancel the influence of disturbance, when a command is given to the control unit, the position will be delayed due to the estimation delay of the disturbance estimation observer due to friction etc. Before the deviation occurs, the disturbance opposing force generating section instantly generates and compensates the torque for canceling this disturbance, so when positioning the mechanical system having a large friction structure,
It is possible to greatly reduce the positioning time.

Further, the servo controller according to the second aspect of the present invention uses the difference between the integral value of the command speed with respect to the load and the position signal actually detected of the load to determine the speed and position. Since it is configured to have a gain changing unit that changes the loop gain, when a command is given to the control unit, the difference between the integrated value of the command speed and the actual position signal is input to the gain changing unit. . When performing digital control,
Since the integrated value of the command speed is delayed by one sample with respect to the position command input to the main controller, this value is smaller than the actual position command by (command speed × sampling period). Therefore, the signal obtained by subtracting the actual position value from the integrated value of this command speed becomes a small value in the acceleration part and deceleration part of the command speed and a large value in the constant speed part, and the command speed becomes zero. After that, in the settling area, the position deviation is the same as that normally used. Therefore, in the gain variable unit, the gain is large when the signal obtained by subtracting the actual position value from the integrated value of the command speed is small, and the gain is small when the signal obtained by subtracting the actual position value from the integrated value of the command speed is large. By setting, a high gain can be output in the area where the influence of static friction is large, and a low gain can be output to the speed and position loop controller to ensure stability in other areas. It is possible to significantly shorten the positioning time when positioning a mechanical system having a large structure.

Further, in the servo control device according to the third aspect of the present invention, when the load is subjected to a disturbance such as friction that changes rapidly, the change occurs before the position deviation occurs due to the estimated delay of the observer. The disturbance resistance generating unit that outputs a pulse-shaped compensation torque for canceling the influence of the fast disturbance, and the difference between the integral value of the command speed for the load and the actually detected position signal of the load, And a gain variable unit for varying the loop gain of the position, so that when a command is given to the control unit, a torque sufficient to cancel the friction is generated before the position deviation occurs due to the friction. Since the counter force generation part is generated instantly,
Disturbances to the controller due to friction are minimized. Furthermore, if the signal from the position detector lags the command even a little in this state, in the area where the difference between the integrated value of the command speed and the actual position signal is small, the variable gain unit will move at a constant speed at high speed. Since a higher gain is output to the speed and position loop controller, the synergistic effect of these causes the occurrence of position deviation due to the estimation delay of the disturbance estimation observer in the static friction region to be extremely small, and the response in the initial stage Can be significantly improved. Further, when the vehicle moves outside the static friction region where the estimation delay of the disturbance estimation observer does not pose a problem, a low gain is output from the gain variable unit, so stable movement is possible.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on an embodiment shown in the drawings.

FIG. 1 is a block diagram showing a servo controller according to an embodiment of the present invention.

In the figure, reference numeral 8 denotes a motor to which a load 9 is connected. The load 9 driven by the motor 8 is, for example, an arm of an assembling robot used in production equipment. A mechanical system having a structure with high friction is used for. The position of the motor 8 to which the load 9 is connected is detected by the position detector 10, and the position signal detected by the position detector 10 is input to the proportional controller 2. Further, the position signal detected by the position detecting unit 10 is converted into a speed signal by a speed calculating unit 11 that performs an integral calculation, and this speed signal is also input to the proportional control unit 2.

The position signal and the speed command signal are compared with the position command signal P _ref and the speed command signal V _ref generated by the command generator 3 inside the proportional control unit 2, and the position signal and the position command signal P _ref are compared. Is input to the position proportional controller 4, and the difference between the speed signal and the speed command signal V _ref added with the output signal from the position proportional controller 4 is input to the speed proportional controller 5. . The signals input to the position proportional controller 4 and the speed proportional controller 5 are
After being multiplied by the respective gains, it becomes the output signal y1 of the proportional control unit 2. Further, the position proportional controller 4 and the speed proportional controller 5 have a variable structure, and a gain P _P of the position proportional controller 4 and a gain V _P of the speed proportional controller 5 are generated by a signal from the gain changing unit 15. The value of can be changed. The gain varying unit 15 outputs the speed command signal V _ref generated by the command generating unit 3 to the integrator 1
The optimum gain is determined and output using the difference between the integrated value integrated in 4 and the actual position signal output from the position detection unit 10.

The speed command signal V _ref generated by the command generator 3 is input to the feedforward unit 6. The feedforward section 6 is a control object by using the inverse of the model transfer function of (amplifier 7 + motor 8), the torque command y2 required to achieve a speed commanded by the speed command signal V _{re f} It is calculated and output.

Further, the disturbance estimation observer unit 12 has a velocity signal calculated by the velocity calculation unit 11 connected to the position detection unit 10 and an output signal ym from the main control unit 1.
And the disturbance element acting on the motor 8 is estimated as an equivalent disturbance torque, and the signal estimated as the equivalent disturbance torque is fed back to the output signal ym from the main control unit 1 as the estimated disturbance torque output y3. .

The output signal y1 from the proportional control section 2 and the output signal y2 from the feedforward section 6
And the sum (y1 + y2 + y3) of the three signals of the output signal y3 from the disturbance estimation observer unit 12 becomes the output signal ym of the main control unit 1.

The disturbance opposing force generator 13 is driven by the motor 8 using the speed command signal V _ref , the actual speed output from the speed calculator 12 and the output signal ym from the main controller 1. The pulsed compensating torque y4 for overcoming the friction acting on the load 9 is output.

Finally, a signal obtained by adding the compensation torque y4 to the output signal ym of the main control section 1 is the control signal yc.
Is supplied to the amplifier 7, torque is generated by the signal amplified by the amplifier 7, the motor 8 rotates, and the load 9 including the arm of the assembling robot is driven.

With the above structure, the servo control device according to this embodiment facilitates high-speed and high-accuracy positioning even with respect to a load consisting of a mechanical system having a structure with large friction as follows. It is possible to realize.

That is, in the servo control device according to this embodiment, as shown in FIG. 1, when a load 9 composed of a mechanical system having a structure with large friction, such as an arm of an assembling robot, is driven. The position command signal P _ref and the speed command signal V _ref are generated from the command generator 3. As the speed command signal V _ref generated by the command generator 3, for example, a signal having a trapezoidal waveform that is often used for motion of a general robot is used as shown in FIG. The position command signal P _ref generated from the command generation unit 3 has a difference with the position signal from the position detection unit 10 that detects the position based on the signal from the motor 8,
The difference between the position command signal P _ref and the actual position signal is input to the position proportional controller 4 and is amplified by the position proportional controller 4 with the gain P _P set by the signal from the gain varying unit 15. It The output signal from the position proportional controller 4 is added to the speed command signal V _ref generated from the command generator 3, and the difference between the added signal and the actual speed signal from the speed calculator 11 is added. Is detected. The signals of these differences are input to the speed proportional controller 5, are amplified by the speed proportional controller 5 with the gain V _P set by the signal from the gain varying unit 15, and are output as the output signal y1 of the proportional controller 2. Is output.

Further, the speed command signal V _ref generated by the command generator 3 is input to the feedforward unit 6, and the model of the (amplifier 7 + motor 8) to be controlled is fed from the feedforward unit 6. The torque command y2 necessary to achieve the speed commanded by the speed command signal V _ref is calculated and output using the reciprocal of the transfer function of.

Further, the disturbance estimation observer section 12 uses the speed signal calculated by the speed calculation section 11 connected to the position detection section 10 and the output signal ym from the main control section 1 to drive the motor 8 The disturbance element acting on is estimated as the equivalent disturbance torque, and the signal estimated as the equivalent disturbance torque is output as the estimated disturbance torque output y3.

Then, the output signal y1 from the proportional control section 2 and the output signal y2 from the feedforward section 6
And the sum (y1 + y2 + y3) of the three signals of the output signal y3 from the disturbance estimation observer unit 12 becomes the output signal ym of the main control unit 1.

By the way, in this embodiment, the output signal y4 from the disturbance reaction force generation unit 13 is added to the output signal ym of the main control unit 1. This disturbance reaction force generation unit 13
In order to overcome the friction acting on the load 9 driven by the motor 8 by using the speed command signal V _ref , the actual speed output from the speed calculator 11 and the output signal ym of the main controller 1. The pulse-shaped compensation torque y4 of is output.

The disturbance reaction force generating section 13 stores a torque value Tf which is previously identified according to the motor 8 and the load 9 and is sufficient to overcome the friction, and the speed command signal from the command generating section 3 is stored. When V _ref is input, the compensation torque y4 is calculated based on the following equation (1). y4 = sign (V _ref ) × Tf + F (ym) (1) Here, sign (V _ref ) is a function that outputs the sign of V _ref .

In this equation (1), F (ym) is the master
The function of the output signal ym of the control unit 1 is represented, and the moving condition of the load 9 is represented.
It can be freely set according to the state of friction. the above
The torque calculated based on the equation (1) is shown in FIG.
The speed command signal V _refUntil becomes zero
Output of the main controller 1 as a pulse-shaped compensation signal of a constant value
The amplifier 7 is added to the signal ym and used as a final control signal.
Is output to Figure 2 shows the movement of a general robot.
Compensation when a commonly used trapezoidal motion waveform is input
The waveform of torque is briefly shown. Also this figure
In the above example, the pulse width of the compensation torque is the speed command signal V_ref
Is the same as the input time, but this pulse width is
By setting it as a function of the actual speed, it can handle various movement conditions.
It is also possible to make it more flexible.

As described above, since the compensating torque is instantaneously supplemented by the disturbance reaction force generating section 13 before the position deviation occurs due to the estimation delay of the disturbance estimating observer, the load 9 composed of a mechanical system having a particularly large frictional structure. Can be positioned at high speed and with high accuracy, and the responsiveness can be significantly improved.

Further, in the above embodiment, the speed command signal V generated by the command generator 3 is supplied to the gain variable unit 15.
A signal obtained by taking the difference between the value obtained by integrating _ref by the integrator 14 and the actual position signal from the position detector 10 is input. By the way, when an analog controller is used as the main controller, the output of the integrator 14 becomes equal to the position command signal P _ref , but when a digital controller is used as the main controller, The output of the integrator 14 is the position command signal P _ref
However, the value becomes smaller by (V _ref (i) × sample period). This is because when a digital controller is used, the velocity signal and the like are discretized and sampled at a constant sample period, and therefore the signal is delayed by an amount corresponding to the sample period. Here, V _ref (i) represents the speed command signal of the i-th sample. Therefore, similarly, the difference between the output of the integrator 14 and the position signal from the position detector 10 is
The value of (V _ref
The value becomes smaller by (i) × sample period).

FIG. 3 shows the relationship between the generally used position deviation signal and (command speed integral value-position signal from the position detector 10) when a trapezoidal speed waveform is input to this digital controller. Is represented. In this figure,
e1 represents the former position deviation signal, and e2 represents the latter (command speed integral value-position signal from the position detection unit 10). Looking at this figure, the former position deviation signal e1
Is instantaneously deviated at a portion where the motor 8 is accelerated, and is almost zero when the maximum speed is shifted to a constant speed, whereas the latter (command speed integral value-position detection unit 10 Deviation signal increases with acceleration, keeps a certain value when shifting to a constant speed at the maximum speed, and gradually decreases with deceleration, and after the command speed becomes zero, it matches the former e1. It can be seen that it has a shape that is symmetrical with the speed command signal V _ref .

Therefore, the signal output from the gain varying unit 15 is the position and velocity loop gains P _P and V in the position proportional controller 4 and the velocity proportional controller 5.
_P is high in a region where the absolute value of the signal e2 of (command speed integrated value-position signal from position detection unit 10) is small, and _P is signal e2 of (command speed integrated value-position signal from position detection unit 10). If it is set to be low in a region where the absolute value of is large, the loop gains P _P and V _P of the position and velocity are increased to increase a large output, especially when moving in a region where the deviation that the influence of static friction is large is small. By outputting the signal y1, a sufficient compensating force to overcome the frictional force can be obtained. Therefore, when positioning the load 9 composed of a mechanical system having a structure with large friction, it is possible to significantly reduce the positioning time.

[0038]

As described above, in the servo control device according to the first aspect of the present invention, the position deviation due to the observer's estimation delay when the load is subject to a disturbance such as friction that changes rapidly. Before the occurrence of the disturbance, it is configured to have a disturbance reaction force generation unit that outputs a pulse-shaped compensation torque to cancel the influence of a fast-changing disturbance. Before a position deviation occurs due to the estimation delay of the disturbance estimation observer, the torque for canceling this disturbance is instantly generated and compensated by the disturbance counter force generator, so when performing positioning control of a mechanical system with large friction. It is possible to significantly reduce the positioning time.

The servo control device according to the second aspect of the present invention uses the difference between the integral value of the command speed with respect to the load and the position signal actually detected from the motor,
Since it is configured to have a gain changing unit that changes the loop gains of the speed and the position, when a command is given to the control unit, the difference between the integrated value of the commanded speed and the actual position signal causes a gain changing unit. Is input to. When performing digital control, the integrated value of the command speed is delayed by one sample with respect to the position command input to the main controller, so this value is (command speed x sample period) less than the actual position command. However, the value becomes smaller. Therefore, the signal obtained by subtracting the actual position value from the integrated value of this command speed becomes a small value in the acceleration part and deceleration part of the command speed and a large value in the constant speed part, and the command speed becomes zero. After that, in the settling area, the position deviation is the same as that normally used. Therefore, in the gain variable unit, the gain is large when the signal obtained by subtracting the actual position value from the integrated value of the command speed is small, and the gain is small when the signal obtained by subtracting the actual position value from the integrated value of the command speed is large. By setting, a high gain can be output in the area where the influence of static friction is large, and a low gain can be output to the speed and position loop controller to ensure stability in other areas. It is possible to significantly shorten the positioning time when positioning a mechanical system having a large structure.

Further, in the servo control device according to the third aspect of the present invention, when the load is subjected to a disturbance such as friction that changes rapidly, the servo control device changes before the position deviation occurs due to the estimated delay of the observer. The disturbance resistance generating unit that outputs a pulse-shaped compensating torque to cancel the influence of the fast disturbance, and the difference between the integrated value of the command speed for the load and the position signal actually detected from the motor And a gain variable unit for varying the loop gain of the position, so that when a command is given to the control unit, a torque sufficient to cancel the friction is generated before the position deviation occurs due to the friction. Since the counter force generation part is generated instantaneously, the disturbance to the controller due to friction can be suppressed to a minimum.
Furthermore, if the signal from the position detector lags the command even a little in this state, in the area where the difference between the integrated value of the command speed and the actual position signal is small, the variable gain unit will move at a constant speed at high speed. Since a higher gain is output to the speed and position loop controller, the synergistic effect of these causes the occurrence of position deviation due to the estimation delay of the disturbance estimation observer in the static friction region to be extremely small, and the response in the initial stage Can be significantly improved. Further, when the vehicle moves outside the static friction region where the estimation delay of the disturbance estimation observer does not pose a problem, a low gain is output from the gain variable unit, so stable movement is possible.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a servo control device according to the present invention.

FIG. 2 is a graph of operation showing an embodiment of a servo control device according to the present invention.

FIG. 3 is a graph of an operation showing an embodiment of a servo control device according to the present invention.

[Explanation of symbols]

1 main control unit, 2 proportional control unit, 3 command generation unit, 4
Position proportional controller, 5 speed proportional controller, 6 feedforward section, 7 amplifier, 8 motor, 9 load, 10
Position detection unit, 11 Speed calculation unit, 12 Disturbance estimation observer unit, 13 Disturbance counter force generation unit, 14 Integrator, 15
Variable gain part, P _ref position command signal, V _ref speed command signal.

Claims (3)

[Claims] 1. A servo control device using a disturbance estimation observer for estimating a disturbance element acting on a load as an equivalent disturbance, wherein when a disturbance having a rapid change such as friction is applied to the load, the position is delayed due to the estimation delay of the observer. A servo control device comprising a disturbance reaction force generation unit that outputs a pulse-shaped compensation torque for canceling the influence of a disturbance that changes rapidly before a deviation occurs. 2. A servo control device using a disturbance estimation observer for estimating a disturbance element acting on a load as an equivalent disturbance, wherein a difference between an integral value of a command speed for the load and an actually detected position signal of the load is calculated. A servo control device, comprising: a gain changing unit that changes a loop gain of velocity and position by using the gain changing unit. 3. A servo control device using a disturbance estimation observer for estimating a disturbance element acting on a load as an equivalent disturbance, wherein when a disturbance having a fast change such as friction is applied to the load, the position is delayed due to the estimation delay of the observer. Before a deviation occurs, a disturbance resistance generating unit that outputs a pulse-shaped compensating torque for canceling the influence of a fast-changing disturbance, an integral value of the command speed for the load, and an actually detected position signal of the load And a gain changing unit that changes the loop gains of the speed and the position by using the difference between the two.