JP4300384B2 - Positioning servo controller - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a positioning servo controller for positioning a control target, and more particularly to a positioning servo controller for positioning a motor.
[0002]
[Prior art]
FIG. 5 is a control block diagram showing a configuration of a conventional positioning servo controller. As shown in FIG. 5, the conventional positioning servo controller includes a position controller 1, a speed controller 2, a torque amplifier 3, a motor 4, and a differentiator 5. This positioning servo controller controls the position θ [rad] of the motor 4 whose inertia is J [N · m · s ² ].
[0003]
The motor 4 is provided with an encoder (not shown) so that the position θ of the motor 4 can be detected by the encoder. A position deviation between the position command θ _r issued from a host device (not shown) and the position θ of the motor 4 is input to the position controller 1. The position controller 1 is a proportional controller that outputs a value obtained by multiplying the deviation by K _p by the position loop gain K _p [1 / s] as a speed command ω _r [rad / s] to the motor 4. The differentiator 5 differentiates the position θ [rad] of the motor 4 and outputs the speed ω [rad / s] of the motor 4. The speed controller 2 inputs a speed deviation between the speed command ω _r [rad / s] and the speed ω [rad / s] of the motor 4 and uses the speed loop gain K _v [1 / s] to calculate the deviation K _v. This is a proportional controller that outputs the multiplied value as a torque command T _ref [N · m] to the motor 4. The torque amplifier 3 inputs a torque command T _ref and generates a torque _Tr to drive the motor 4. That is, the positioning servo controller is for to follow the position theta of the motor 4 to the position command theta _r, the position theta of the motor 4, the position response to the position command theta _r.
[0004]
In such a conventional positioning servo controller, a feedback control system is used in which positioning control is performed based on the fed back position response θ of the motor 4. As described above, the positioning servo controller normally has a speed loop process as a minor loop in the position loop process.
[0005]
However, in such a feedback control type positioning servo controller, the values of the position loop gain K _p and the speed loop gain K _v are finite values and have upper limit values. Therefore, the position response θ of the motor 4 does not completely coincide with the position command θ _r, and so-called servo delay occurs.
[0006]
FIG. 6 is a graph showing the operation of a conventional positioning servo controller. 6A shows the position command θ _r and the position response θ, and FIG. 6B shows the position command θ _r and the differentials dθ _r / dt and dθ / dt of the position response θ. ing. As shown in FIGS. 6A and 6B, dθ _r / dt is obtained by accelerating the motor 4 at a constant acceleration so that the speed reaches the steady speed V [rad / s], and the steady speed V is reached for a predetermined time. The command is to decelerate at a constant acceleration after moving at. In such a case, the maximum position deviation is V / Kp [rad], and the time from when the value of dθ _r / dt reaches 0 until the position response θ actually reaches the value of the position command θ _r is , 1 / K _p [s] and becomes longer in proportion.
[0007]
In FIG. 6, acceleration / deceleration time = 0.1 [s], steady speed V = 100 [rad / s], predetermined time = 0.2 [s], and position loop gain K _p = 25 [1 / s. ], When the velocity loop gain K _v = 200 [1 / s] and the inertia J = 1 [N · m · s ² ], the commands θ _r and dθ _r / dt and the responses θ and dθ / dt change. It is shown. In FIG. 6, the steady-state deviation is V / K _p = 100/25 = 4 [rad], and the value of the position response θ actually reaches the value of the position command θ _r after dθ _r / dt becomes 0. The time is 0.1 [s].
[0008]
In such a positioning servo controller, a feedforward control method may be used together with a feedback control method in order to eliminate the above-described servo delay. FIG. 7 is a control block diagram showing the configuration of a positioning servo controller that uses the feedforward control method together with the feedback control method. This positioning servo controller includes feedforward controllers 6 and 7 in addition to the components of the positioning servo controller of FIG. Feedforward controller 6 differentiates the position command theta _r Enter the position command theta _r, and outputs a K _ff1 value multiplied by by its differential value first feedforward gain K _ff1 [1 / s]. This value is the first feedforward control amount that is added to the speed command ω _r [1 / s] output from the position controller 1.
[0009]
By doing so, in the positioning servo controller of FIG. 7, the speed loop process is performed based on the speed command that does not include the servo delay element generated directly from the position command θ _r, so that it is more than in the case of only the feedback control. Servo delay can be eliminated. Further, the feedforward controller 7 receives and differentiates the first feedforward compensation amount output from the feedforward controller 6, and obtains a value obtained by multiplying the derivative by K _ff2 by the second feedforward gain K _ff2 . 2 is output as the feedforward compensation amount. This second feedforward compensation amount is added to the value output from the speed controller 2, and the added value is input to the torque amplifier 3 as the torque command Tr. In this way, the torque amplifier 3 can drive the motor 4 based on the torque command Tr that does not include a servo delay element.
[0010]
As described above, the positioning servo controller in FIG. 7 can compensate for the servo delay generated by the feedback control by performing the speed feedforward control and the torque feedforward control.
[0011]
FIG. 8 is a control block diagram in which each block of the positioning servo controller of FIG. 7 is simplified. As shown in FIG. 8, the control performance of this positioning servo controller is determined by the values of feed forward gains K _ff1 and K _ff2 . Therefore, in the positioning servo controller of FIG. 7, the feedforward gains _Kff1 and _Kff2 are set to optimum values, and the motor 4 is controlled in a state where the servo delay is minimized.
[0012]
If the feed forward gain K _ff1 = 1, the control block diagram of this positioning servo controller is as shown in FIG. Further, when the feed forward gain K _ff2 = J, the value of the transfer function G from the position command θ _r to the position response θ is 1, and ideally there is no delay between the position command θ _r and the position response θ. The servo delay of the positioning servo controller becomes zero.
[0013]
However, in reality, the physical quantity such as inertia J of the motor 4 to be controlled is often not completely grasped, and it is difficult to set the values of the feed forward gains K _ff1 and K _ff2 to optimum values. is there. In such a case, phenomena such as overshoot and undershoot occur when the motor 4 is positioned. For example, if K _ff2 = J, the servo delay of the positioning servo controller is 0, but if the value of J is unknown, the value of the feedforward gain K _ff2 cannot be set to the value of J. Therefore, overshoot or undershoot occurs in the response. FIG. 10 shows the fluctuation of the speed response dθ / dt, which is the derivative of the positioning servo controller position response θ when the value of the feedforward gain K _ff2 is not optimally set. In FIG. 10, K _ff2 = 0.5 = J / 2. FIG. 10B is an enlarged view of the portion A in FIG.
[0014]
As shown in FIG. 10B, an overshoot occurs in the speed response dθ / dt. In order to eliminate such overshoot, measures such as lowering the value of the feedforward gain _Kff1 or providing a filter at the output of the feedforward controller 7 have been taken. There was a problem that the servo delay was caused again by such measures.
[0015]
[Problems to be solved by the invention]
As described above, in the conventional positioning servo controller, when the physical quantity of the motor that affects the control is unknown, the value of the control parameter such as the feed forward gain cannot be set to the optimum value. There was a problem that an overshoot or undershoot occurred in the response and a good control response could not be obtained.
[0016]
An object of the present invention is to provide a positioning servo controller that can obtain a good control response even if the physical quantity of the motor is unknown.
[0017]
[Means for Solving the Problems]
In order to solve the above problems, positioning servo controller of the present invention,
Position control means for amplifying a position deviation between a position command issued from a host device and a position to be controlled by a position loop gain and outputting the position deviation;
A speed feedforward having a speed command obtained by adding a first feedforward compensation amount obtained by amplifying a value obtained by differentiating the position command by a first feedforward gain to a value output from the position control means. Control means;
Speed control means for amplifying and outputting a speed deviation between the speed command and the speed to be controlled by a speed loop gain;
A value obtained by adding a second feedforward compensation amount obtained by amplifying a value obtained by differentiating the first feedforward compensation amount by a second feedforward gain to a value output from the speed control means is an acceleration command. Acceleration feed forward means to perform,
Acceleration control means for amplifying an acceleration deviation between the acceleration command and the acceleration to be controlled by an acceleration loop gain and outputting the torque command as a torque command;
A torque amplifier that drives the object to be controlled based on the torque command ;
Bei to give a,
The second feedforward gain is set to 1 .
Other positioning servo controllers of the present invention are:
Position control means for amplifying a position deviation between a position command issued from a host device and a position to be controlled by a position loop gain and outputting the position deviation;
A speed feedforward having a speed command obtained by adding a first feedforward compensation amount obtained by amplifying a value obtained by differentiating the position command by a first feedforward gain to a value output from the position control means. Control means;
Speed control means for amplifying and outputting a speed deviation between the speed command and the speed to be controlled by a speed loop gain;
A value obtained by adding a second feedforward compensation amount obtained by amplifying a value obtained by differentiating the first feedforward compensation amount by a second feedforward gain to a value output from the speed control means is an acceleration command. Acceleration feed forward means to perform,
An acceleration control means for amplifying an acceleration deviation between the acceleration command and the acceleration to be controlled by an acceleration loop gain and outputting it as a torque command;
A torque amplifier that drives the object to be controlled based on the torque command;
With
When the inertia value to be controlled is known, the second feedforward gain is set based on the inertia value and the acceleration loop gain.
[0018]
The positioning servo controller according to the present invention includes an acceleration control means for outputting, as a torque command, a value obtained by amplifying an acceleration deviation between an acceleration command and an acceleration to be controlled by an acceleration loop gain, thereby outputting a position command as a position response Even if the physical quantity of the controlled object included in the coefficient of the transfer function is unknown, the acceleration loop gain value in that coefficient becomes the denominator of the physical quantity of the controlled object, and the acceleration loop gain value is set appropriately. Since the influence of the value of the physical quantity to be controlled on the position response can be ignored by setting the value, a favorable control response can be obtained by setting the acceleration loop gain to an appropriate value.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Next, a positioning servo controller according to an embodiment of the present invention will be described in detail with reference to the drawings. In all the drawings, the same reference numerals denote the same components.
[0020]
FIG. 1 is a control block diagram showing the configuration of the positioning servo controller of this embodiment. The positioning servo controller of the present embodiment is different from the conventional positioning servo controller of FIG. 7 in that an acceleration controller 8 and a differentiator 9 are provided. The differentiator 9 performs second-order differentiation on the position response θ of the motor 4 and outputs the acceleration of the motor 4. The acceleration controller 8 calculates an acceleration deviation between a value obtained by adding the value output from the speed controller 2 and the value output from the feedforward controller 7 and the acceleration of the motor 4 output from the differentiator 9. enter a proportional controller for outputting the torque amplifier 3 a value of acceleration deviation was K _a multiplied by the acceleration loop gain K _a as the torque command T _r.
[0021]
A simplified version of the control block diagram of FIG. 1 is shown in FIG. In order to further simplify the control block diagram of FIG. 2, _assuming that the feedforward gain K _ff1 = 1, the control block diagram of FIG. 2 is simplified as the control block diagram of FIG. When the control block diagram of FIG. 3 is compared with the control block diagram of FIG. 9, the coefficient of the term of S ² is J in the control block diagram of FIG. in the control block diagram, and it has a 1 + J / K _a. Since the value of the acceleration loop gain K _a in the transfer function G is a denominator of inertia J of the motor 4, the acceleration loop gain K value of _a is greater the J / K _a approaches zero. That is, even when the value of inertia J is not clear, by setting the value of the acceleration loop gain K _a to an appropriate value, it is possible to reduce the influence of inertia J with respect to the position response theta. Further, in the control block diagram of FIG. 3, if the feedforward gain K _ff2 = 1, the transfer function G between the position command θ _r and the position response θ can be made substantially 1, and the position of the position response θ The delay with respect to the command θ _r can be eliminated.
[0022]
In FIG. 4, K _p = 25 [1 / s], K _v = 200 [1 / s], K _a = 10, K _ff1 = 1 [1 / s], and K _ff2 = 1 [1 / s]. It is a graph which shows operation | movement of the positioning servo controller of this embodiment at the time.
[0023]
FIG. 4 shows changes in the differentials dθ / dt and dθ / dt of the position command θ _r and the position response θ. Dθ _r / dt in FIG. 4 has the same waveform as dθ _r / dt in FIG. Further, in FIG. 4, and acceleration and deceleration time, constant speed, a predetermined time, the position loop gain K _p, the speed loop gain K _v, and the value of inertia J is the same as the value in FIG. 10, the acceleration loop gain K _a = 10, feed forward gain _Kff1 = 1, _Kff2 = 1. 4B, which is an enlarged view of the portion B in FIG. 4A, and FIG. 10B, it can be seen that the amount of overshoot in the speed response dθ / dt is reduced.
[0024]
As described above, the positioning servo controller of this embodiment includes the acceleration controller 8 that outputs a value obtained by amplifying the acceleration deviation between the acceleration command and the acceleration of the motor 4 by the acceleration loop gain Ka as _a torque command. By doing so, in the positioning servo controller of the present embodiment, even if the inertia J of the motor 4 included in the coefficient of the transfer function G having the position command θ _r as an input and the position response θ as an output is unknown, transmitting the acceleration loop gain K _a in the function G is the denominator of the inertia J of the motor 4 during its coefficients, the inertia J of the acceleration loop gain K motor by the value of _a is set to an appropriate value 4 The influence on the position response θ can be ignored. Therefore, the positioning servo controller of this embodiment can obtain a good control response.
[0025]
Further, in the positioning servo controller of the present embodiment, even if the value of the inertia J of the motor 4 is changed by the value of the acceleration loop gain K _a is set to an appropriate value, the position response of the inertia J of the motor 4 Since the influence on θ can be ignored, a good control response can be obtained.
[0026]
Further, the positioning servo controller of the present embodiment, when the value of inertia J is clear, by the _{K ff2 = 1 + J / K} a, can also be a transfer function G = 1. Therefore, the positioning servo controller of the present embodiment can optimally position the motor 4 regardless of whether the value of the inertia J is clear.
[0027]
【The invention's effect】
As described above, the positioning servo controller of the present invention includes the acceleration controller that outputs a value obtained by amplifying the acceleration deviation between the acceleration command and the actual acceleration of the motor by the acceleration loop gain as a torque command. Even if the inertia of the motor included in the coefficient of the transfer function that outputs the position response is unknown, the value of the acceleration loop gain in the transfer function becomes the denominator of the inertia of the motor. Therefore, by setting the acceleration loop gain value to an appropriate value, the influence on the position response of the inertia of the motor can be ignored. Therefore, the positioning servo controller of the present invention can obtain a good control response.
[Brief description of the drawings]
FIG. 1 is a control block diagram showing a configuration of a positioning servo controller according to an embodiment of the present invention.
FIG. 2 is a simplified control block diagram of the control block diagram of FIG.
FIG. 3 is a simplified control block diagram of the control block diagram of FIG. 2;
FIG. 4 is a graph showing the operation of the positioning servo controller according to the embodiment of the present invention.
FIG. 5 is a control block diagram showing a configuration of a conventional positioning servo controller.
FIG. 6 is a graph showing the operation of a conventional positioning servo controller.
FIG. 7 is a control block diagram showing a configuration of a positioning servo controller that uses a feedforward control method together with a feedback control method.
FIG. 8 is a control block diagram obtained by simplifying the control block diagram of FIG. 7;
FIG. 9 is a simplified control block diagram of the control block diagram of FIG.
FIG. 10 is a graph showing the operation of a conventional positioning servo controller.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Position controller 2 Speed controller 3 Torque amplifier 4 Motor 5, 9 Differentiator 6, 7 Feed forward controller 8 Acceleration controller

Claims (2)

Position control means for amplifying a position deviation between a position command issued from a host device and a position to be controlled by a position loop gain and outputting the position deviation;
A speed feedforward having a speed command obtained by adding a first feedforward compensation amount obtained by amplifying a value obtained by differentiating the position command by a first feedforward gain to a value output from the position control means. Control means;
Speed control means for amplifying and outputting a speed deviation between the speed command and the speed to be controlled by a speed loop gain;
A value obtained by adding a second feedforward compensation amount obtained by amplifying a value obtained by differentiating the first feedforward compensation amount by a second feedforward gain to a value output from the speed control means is an acceleration command. Acceleration feed forward means to perform,
Acceleration control means for amplifying an acceleration deviation between the acceleration command and the acceleration to be controlled by an acceleration loop gain and outputting the torque command as a torque command;
A torque amplifier that drives the object to be controlled based on the torque command ;
Equipped with a,
The second feedforward gain is set to 1;
Positioning servo controller you wherein a. Position control means for amplifying a position deviation between a position command issued from a host device and a position to be controlled by a position loop gain and outputting the position deviation;
Speed feedforward having a speed command obtained by adding a first feedforward compensation amount obtained by amplifying a value obtained by differentiating the position command by a first feedforward gain to a value output from the position control means. Control means;
Speed control means for amplifying and outputting a speed deviation between the speed command and the speed to be controlled by a speed loop gain;
A value obtained by adding a second feedforward compensation amount obtained by amplifying a value obtained by differentiating the first feedforward compensation amount by a second feedforward gain to a value output from the speed control means is an acceleration command. Acceleration feed forward means to perform,
An acceleration control means for amplifying an acceleration deviation between the acceleration command and the acceleration to be controlled by an acceleration loop gain and outputting it as a torque command;
A torque amplifier that drives the controlled object based on the torque command;
With
When the inertia value to be controlled is known, the second feedforward gain is set based on the inertia value and the acceleration loop gain.
A positioning servo controller.

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