JP2672539B2 - Automatic control device - Google Patents

Description

The present invention relates to an automatic control device that controls a servo mechanism or the like, and more particularly to an automatic control device that is suitable for controlling an XY plotter or a robot. [Prior Art] When it is required to maintain a sufficient accuracy not only for positioning on a movable part but also for its movement locus itself as in the control of an XY plotter or robot, conventionally, for example, As disclosed in Japanese Patent Publication No. 58-9441, a target position required to give a desired control characteristic,
A method has been proposed in which control is performed using signals that respectively command a target velocity and a target acceleration. According to this method, a position control characteristic that is almost the same as the target can be obtained within the limit value of the controlled object, and the disturbance It is possible to obtain a control in which the undershoot against such as is sufficiently suppressed. [Problems to be Solved by the Invention] In the above-mentioned conventional technology, the target acceleration is applied to the controlled object, the speed deviation of the controlled object with respect to the target speed and the positional deviation of the controlled object with respect to the target position are obtained, and these deviations are minimized. The compensation signal necessary to make the value converge is further applied to the controlled object.Therefore, no consideration is given to the fact that it is necessary to calculate the velocity deviation in addition to the position deviation. There has been a problem that the structure and the processing are complicated because it is necessary to always detect the position of the controlled object and the speed thereof and to calculate the position deviation and the speed deviation based on them. An object of the present invention is to provide an automatic control device that does not require calculation of both velocity deviation and position deviation with respect to a controlled object, and that can obtain sufficient control responsiveness. [Means for Solving Problems] The above object is to provide a feedforward compensator in a transmission system of a signal from a simulated circuit to be controlled, and to adjust the characteristics of the fedforward compensator to the simulated circuit. It is achieved so that the output signal has a characteristic of following the signal representing the control result of the controlled object, and a characteristic including the transfer function of the simulation circuit. [Operation] Since the feedforward compensator that receives the output signal from the simulated circuit to be controlled can be designed in consideration of all the signals inside the simulated circuit, both the speed deviation and the position deviation can be considered. It is possible to obtain the required characteristics without the need for calculation, and this feedforward compensator has a transfer function from the command value to the output of the controlled system from the command value to the output of the control system simulator. Since they can be designed to match, the output of the controlled object can be operated as the output of the simulated circuit of the controlled object. [Embodiment] Hereinafter, an automatic control device according to the present invention will be described in detail with reference to an illustrated embodiment. FIG. 1 shows an embodiment in which the present invention is applied to position control of a table by driving a motor. In the drawing, 4 represents a control target, and the motor 1 is driven to position the table 2. The motor 1 is driven by the current amplifier 3. Then, in the controlled object 4 including the motor 1, the table 2 and the current amplifier 3, the table position x which is the output signal thereof is detected by the position detector 5. Next, 6 is a control device, which receives the position command x _R from the position command generator 7 and outputs a current command i ^* so that the table position x becomes the position command x _{R in a} steady state. Then, this current command i ^* is input to the current amplifier 3. The control device 6 is composed of a feed back controller 8 for determining the characteristics against disturbance, a control system simulation device 9 for obtaining a desired response to the position command x _R , and a feed forward compensator 10, and further a control system simulation device 9 Is composed of a controlled object simulation circuit 11 simulating a controlled object and a controller simulation circuit 12. FIG. 2 shows the details of the control system simulating device 9. The controlled object simulating circuit 11 inputs the model current i _M simulating the current i of the motor 1 and simulates the motor speed ω and the table position x, respectively. The model velocity ω _M and the model position x _M are calculated. Further, the controller simulation circuit 12 calculates the speed command ω _{R based} on the difference between the position command x _R and the model position x _M. The speed limiter 13 is operated so as to operate at a maximum speed ω _MAX or less that the motor can tolerate. Then, the model current i _M is calculated from the difference between the speed command ω _R and the model speed ω _M. The current limiter 14 is used to operate the motor 1 at a maximum current i _MAX or less that can be passed. By configuring the control system simulator 9 in this way,
Since the model position x _M does not need to consider parameter fluctuations, disturbances, etc., the desired response can always be obtained for the position command x _R. Next, FIG. 3 shows an example of the configuration of the feed back controller 8. Here, the transfer function Hi ^* x (S) from the current command i ^* to the table position x in the controlled object 4 is , The input of the feed back controller 8 can be obtained by constructing as shown in the block diagram of FIG.
The transfer function H _ilx (s) from i _l to the table position x can be expressed by the following equation. Therefore, from the equation (2), the transfer function H _ilx (s is changed by changing the gains k ₀ , k ₁ , k ₂ , k ₃ , k ₄ , k ₅ in each block in the embodiment of FIG. ) Can be set arbitrarily. In general, the transfer function H _iMx (s) of the equation (2) is
For simplicity, Often. Next, the feedforward compensator which is a feature of the present invention
The setting method of 10 characteristics will be described. Now, transfer function Hi _M x _M (s) from model current i _M to model position x _M in controlled object simulation circuit 11 _Let us consider the case where H _ilx (s) is given by the equation (3). At this time, the transfer function G of the feedforward compensator 10
Set _F (s) as follows: By setting as in the equation (5), the transfer function from the model current i _M to the table position x is calculated as the model current i _M.
To the model position x _M can be matched with the transfer function Hi _M x _M (s). Therefore, the table position x can always be made to coincide with the model position x _M even during a transition. The step response to the position command x _{R at} that time is
Shown in the figure. At this time, in the control system simulating device 9, the model position x _M is the limit value of the controlled object (that is, the maximum speed ω
Since it can be designed to respond at high speed within _MAX , maximum current i _MAX ), the table position x can also obtain a response as shown in FIG. In addition, the control system simulator 9 gives characteristics having ideal responsiveness, and as a result, the feedforward compensator 10 is provided.
When there is no parameter change of the controlled object, the table position x operates so as to match the model position x _M , so only the deviation between the table position x and the model position x _M due to the parameter change is compensated by the feed back controller 8. do it. Therefore, the feed back controller 8 can configure a control system by paying attention to the parameter variation, and can perform control (so-called robust control) in which the characteristic changes little with respect to the influence of the parameter variation. According to the present embodiment, it is possible to perform position control with good responsiveness within the limit value of the controlled object without detecting the motor speed ω. The input i _l of the feedback controller 8
There is only one, and when the control device 6 is composed of a plurality of microprocessors, it has the feature that it can be easily separated at this input i _l part. Further, according to this embodiment, a limiter is provided inside the control system simulating device, and even if an attempt is made to perform an excessive operation, the limiter is used to limit the movement. It does not work and is highly safe. Next, FIG. 5 shows another embodiment of the feedforward compensator 10. In the feedforward compensator 10 according to this embodiment, not only the model current i _M but also the model current i _{M is} inputted as its input signal. The model position x _M obtained based on the model power supply i _M is also used, and the model current compensator 15 that inputs the model current i _M and the model position compensator 16 that inputs the model position x _M The output of the feedback controller 8 is supplied as the input i _l of the feedback controller 8. Then, at this time, the characteristics of the feedforward compensator 10 are determined so that the table position x matches the model position x _M. That is, the transfer function G of the model current compensator 15 and the model position compensator 16 is set so as to be equivalent to the equation (5).
_FI (s) and G _FX (s) are set as follows. G _FX (s) = 1 (7) As a result, the transfer function Hi _M x (s) from the model current i _M to the table position x and the model current i _M to the model position x _M
The transfer functions Hi _M x _M (s) up to can be matched. Therefore, according to the present embodiment, by using not only the model current i _M but also the model position x _M , the feedforward compensator 10 having a simple characteristic can configure a position control system with good responsiveness. . Next, FIG. 6 shows another embodiment of the present invention in the case where the speed control system is already configured for the controlled object.
In FIG. 6, 17 is a speed controller, which calculates a current command i ^* from a speed command ω ^* described later and a motor speed ω that feeds back from the controlled object 4, and the current command i ^* is calculated.
^The speed control system 18 is configured by inputting ^* to the controlled object 4. If there is such an existing speed control system 18, the feed back controller 8 calculates not the current command i ^* but the speed command ω ^{* based} on the input i _l and the table position x. One method of this calculation is shown in FIG. As a result, an optimum feedback control system can be constructed. The feedforward compensator 10 may select the characteristics so that the table position x always matches the model position x _M. Therefore, according to the present embodiment, it is possible to configure a position control system having good characteristics while using the existing speed control device as it is. By the way, in the above description, the case where the present invention is applied to the XY table position control has been described, but the present invention is not limited to this, and can also be applied to position control of robots, XY plotters, machine tools, and the like. Needless to say, the present invention is also applicable to a motor speed control device and a plant control device. Further, according to the present invention, since the output of the controlled object operates in accordance with the output of the control system simulating device, it is possible to perform highly accurate trajectory control by giving a movement path such as a robot with the output of the control simulating device. it can. EFFECTS OF THE INVENTION According to the present invention, it is possible to obtain a target output without calculating the deviation between the state quantity of the controlled object (speed, position, etc.) and the corresponding state quantity of the controlled object simulation circuit. Therefore, there is an effect that the control system can be configured without detecting all state quantities.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment in which an automatic control device according to the present invention is applied to position control of an XY table, and FIG. 2 is a block diagram showing an embodiment of a control system simulating device. FIG. 3 is a block diagram showing an embodiment of the feedback control device, FIG. 4 is a characteristic diagram for explaining the operation, and FIG. 5 is a block diagram showing another embodiment of the feedforward compensator. FIG. 6 is a block diagram showing another embodiment of the present invention, and FIG. 7 is a block diagram showing another configuration example of the feed back controller. 1 ... motor, 2 ... XY table, 3 ... current amplifier,
4 ... Control object, 5 ... Position detector, 6 ... Control device,
7 ... Position command generator, 8 ... Feed back controller, 9 ... Control system simulation device, 10 ... Feed forward compensator, 11 ... Control target simulation circuit, 12 ... Controller simulation circuit, 13 ...... Speed limiter, 14 …… Current limiter, 15 ……
Model current compensator, 16 …… Model position compensator, 17 …… Speed controller, 18 …… Speed control system.

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Katsuji Marumoto               4026 Kuji-cho, Hitachi City, Ibaraki Prefecture Co., Ltd.               Hitachi Research Laboratory, Hitachi Research Laboratory                (56) References JP-A-62-217304 (JP, A)                 JP 62-212801 (JP, A)

Claims (1)

(57) [Claims] In an automatic control device of a method in which an operation command value for a controlled object is created by a feedforward control device including a simulated circuit of the controlled object, a feedforward compensation circuit is provided in a transmission path of the operation command value, and the feedforward compensation circuit The characteristic is configured such that the output signal of the simulation circuit follows the detection signal representing the control result of the controlled object and includes the transfer function of the simulation circuit. Automatic control device. 2. The automatic control device according to claim 1, wherein the simulation circuit is configured to include a limiting function corresponding to the operation allowable range of the controlled object.