JPH0259027B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a control device for a conveying device that conveys and supplies conveyed materials such as molding materials.

[Conventional technology]

Conventionally, as this type of conveyance device, for example,
JP-A-58-157565 and JP-A-58-181461
There is a molten metal supply device as described in the above publication. This molten metal supply device is a device as shown in FIG.
The pouring spout (hereinafter referred to as sleeve) 1
4 is automatically poured into the tank.

A ladle 3 that scoops up and conveys molten metal is rotatably supported by an arm 2 about _P8 , and arm ₂ is rotatably supported by an arm 1 about P2. Further, the arm 1 is rotatably supported on the body 10 around _P1 . The rotation of arm 1 around P ₁ and the rotation of arm 2 around P ₂ are performed by the drive motor 4, and the rotation movement of arm 2 around P ₃ is caused by the drive motor 4.
The rotational movement around the arm 1 is independently driven by a drive motor 6, and by detecting the rotation amount of each motor shaft end with rotary encoders (hereinafter referred to as RE) 7 and 9, the rotation angle θ ₁ of the arm 1 or the arm 2 rotation angle θ ₂ and ladle 3 inclination angle θ ₃
It is becoming possible to recognize. A balance weight 12 is attached to the arm 1 by a connecting rod 13. Further, although the drive mechanism from the motors 4 and 6 to the driven parts, the arms 1 and 2 and the ladle 3, is not shown in this figure, the structure is briefly described as follows. That is, arm 1 is given rotation around P ₁ by motor 4 via a gear mechanism, and arm 2 is coaxial with the gear mechanism of arm 1 via motor 4 via a gear mechanism.
The rotation is given as a rotation around P ₁ and then as a rotation around P ₂ due to chain-sprocket conduction through the arm 1. Also, Ladle 3
is given by motor 6 via a gear mechanism as a rotation around _P1 , which is coaxial with the drive mechanism of arm 1, and then given as a rotation around _P2 by chain-sprocket transmission passing through arm 1. ,
Further, it is given as a rotation around _P3 by chain-sprocket conduction passing through the arm 2.

By the way, the locus a shown by the two-dot chain line in the figure shows the path along which the rotation center P3 of the ladle ₃ moves.
By programming the relationship between θ ₁ , θ ₂ , and θ ₃ , an arbitrary trajectory can be obtained while keeping the ladle 3 horizontal at all times. It is assumed that the locus a is within the xz plane shown in this figure, and the y axis is perpendicular to this plane.

Next, the measuring operation of the ladle 3 in the holding furnace 11 will be explained using FIGS. 5a to 5d. That is, FIG. 5a shows a state in which the center of rotation P ₃ of the ladle 3 has reached the position a ₁ from the direction b in the figure on the trajectory a shown in FIG. 4. At this position, the conveyance operations of the arms 1 and 2 are temporarily stopped, and the ladle 3 is tilted in the direction of the arrow shown in the figure. Ladle 3 has a predetermined inclination angle (measurement angle)
When it is tilted by θ ₃ , the tilting operation stops, and as shown in FIG. do. After waiting until enough molten metal 15 enters the ladle 3, the arm moves upward in the direction of the arrow shown in FIG. Return to In other words, the amount of molten metal pumped up by the ladle 3 is given as a function of the metering angle θ ₃ . After this, as shown in Fig. 5d, when the rotation center P ₃ and point _a coincide, the ladle 3 is returned to the horizontal position (θ ₃ = 360°) and moved in the f direction. Prepare for transport operation. In this way, Ladle 3
The weighing operation is completed.

After such a weighing process, the rotation center _P3 of the ladle 3 is moved from point a according to the locus a in Fig. ₄ under the drive control of arms 1 and 2.
a Move up to ₃ points. At this time, since the ladle 3 is controlled to always maintain a horizontal state, the molten metal being transported will not spill.

FIG. 6 is a characteristic diagram showing the change in the moving speed v of the rotation center P ₃ with respect to time t at this time. As shown in the figure, the ladle 3 is accelerated from point a ₁ with an acceleration α ₁ and moves at a relatively high speed v ₁ , but when it rapidly decelerates at the final point a ₃ , the ladle 3
There is a risk that the molten metal stored inside may spill out. Therefore, after decelerating to a speed v ₂ at a single deceleration α ₂ at point a ₂ ahead of a ₃ , a predetermined deceleration α ₃ is applied again near the end point a ₃ to stop the vehicle. Since the posture of arms 1 and 2 can be fixed at the end point _a3 by RE7, position feedback control is performed so that the arms 1 and 2 stop at a predetermined position, and the positions are controlled at a predetermined speed.
Feedback control is also performed on the moving speed v so that v ₁ and v ₂ are obtained at predetermined times.
A block diagram of such a feedback operation is shown in FIG. 7.

In the same figure, G _p : Position feedback gain G _v : Velocity feedback gain G(s) : Transfer function of this arm drive system θ _io : Target arm posture θ _put : Current arm posture be.

[Problem that the invention seeks to solve]

However, with such a molten metal supply device, it is necessary to appropriately change the amount of molten metal that the ladle 3 attempts to pump up depending on the shape and type of the molded product, that is, it is necessary to change the metering angle θ ₃ , and the amount of molten metal is If you change , the weight carried by the arm (ladle + molten metal weight) will change, which will change the amount of inertia the arm end has. The position and velocity feedback gains G _p and G _v are set to constant values, and if the inertia of the arm end changes as described above,
This resulted in a problem of poor controllability. Particularly, this phenomenon is strongly dominated by the speed feedback gain _Gv , and depending on the amount of molten metal in the ladle 3, it becomes as shown in FIG. 8, for example. That is,
In the figure, θ _io on the vertical axis is the target arm posture, and the horizontal axis is time. For a given amount of molten metal, the curve
It has a favorable characteristic of smoothly and quickly reaching the target arm posture θ _io and stopping as shown in N ₁ , but as the amount of molten metal increases, the curve shows N ₂ , and as the amount of molten metal decreases, the curve
This results in defective characteristics like N ₃ . If molding is to be carried out over a long period of time with the same amount of molten metal, it is possible to do so by determining and setting the speed feedback gain _Gv according to the amount of molten metal. If the amount of molten metal is adjusted frequently, such as by _changing it with It was hot. Furthermore, this method cannot be applied to a rotary die-casting machine, etc., in which molds with different weights (molten metal amounts) of molded products are mounted on the machine at the same time, and the molds are sequentially molded.

Furthermore, if the vertical position of the sleeve 14 changes due to a change in the shape of the molded product, the height of the molten metal supply device itself is usually changed accordingly, but unlike that, the height shown in FIG. As shown, when the sleeve 14 changes to a position such as 14a or 14b, the trajectory a changes to a′ or a′ or
It is also conceivable to change the shape to "a".Also, if there are no obstacles on the trajectory of the ladle 3, it may be possible to change the shape to a shape like trajectory a, as shown in Fig. It may be possible to take a trajectory such as a, a''''' where the distance is shortened, and the trajectory to be given is arbitrary and depends on the operator's instructions.In other words, the predetermined position a ₃ , The change trajectory of the posture of arm 1 or 2 until it reaches a ₃ ′ or a ₃ ″ is arbitrary, and the moment of inertia of the driven part handled by motor 4 can change freely accordingly. . Therefore, even if the control shown in Fig. 6 is performed, the speed feedback gain
If G _v is constant, it will not be possible to follow changes in the moment of inertia due to changes in attitude, so as shown in Figure 8, control characteristics such as N ₁ will be determined by the appropriate value of G _v at a certain moment of inertia value. Even if it is obtained, changing the trajectory a changes the posture of the arm, and as a result, the moment of inertia changes, resulting in characteristics such as N ₂ and N ₃ .

[Means for solving problems]

The present invention has been made in view of these points, and calculates the weight of the material being transported into the ladle based on the measuring angle of the ladle, and adds the weight of the ladle itself to the determined weight of the transported material. A transport weight calculation means for calculating the transport weight, a posture calculation means for calculating the momentary posture of the transport arm based on the rotation angle of the transport arm, and a transport weight calculation means for determining the transport weight calculated by the transport weight calculation means and the transport calculated by the posture calculation means. A moment of inertia calculating means for calculating the moment of inertia of the driven parts including the ladle and the transfer arm based on the momentary posture of the arm, and a speed feed based on the moment of moment of inertia calculated by the moment of inertia calculating means. The apparatus is equipped with a gain calculating means for calculating the back gain every moment, and the operation of the transport arm is controlled by the speed feedback gain calculated by the gain calculating means.

[Effect]

Therefore, according to the device of the present invention, the speed feedback gain changes in accordance with the change in the moment of inertia of the driven part.

〔Example〕

Hereinafter, a control device for a conveying device according to the present invention will be explained in detail. FIG. 1 is a block diagram showing one embodiment of this control device, which is used, for example, in the molten metal supply device shown in FIGS. 9 and 10. In addition, No. 9, 1
The device shown in FIG. 0 is almost the same as the device shown in FIG. 4, but the difference is that in the devices shown in FIGS. Another advantage is that the drive motor 5 and RE8 for rotating the arm 2 are provided separately. Therefore, the rotation of arm 1 and arm 2 can be controlled separately. Further, a drive motor 6 and RE9 for rotating the ladle 3 are arranged on the side surface of the body 10.

In FIG. 1, reference numeral 16 denotes a conveyed weight calculation means that receives the angle θ ₃ of the ladle 3 recognized by the RE 9 as an input and calculates the conveyed weight. That is, a signal corresponding to the weighing angle θ ₃ explained using FIG. 5 is input to the conveyed weight calculation means 16 via RE9. The amount W of molten metal pumped by ladle 3 is
Since there is a one-to-one correspondence with this weighing angle θ ₃ , the conveyed weight
W _a can be determined by W _a =W (θ ₃ )+Wl (1). However, Wl is the weight of the ladle.

On the other hand, when arms 1 and 2 move to conveyance operation,
arm 1 and 2 moment by moment (e.g. 0.1~
(every 100msec) signals according to rotation angles θ ₁ and θ ₂
From RE7 and RE8, it is input to the attitude calculation means 17, and the attitude calculation means 17 recognizes it as the attitude of the driven part.
That is, with respect to arm 2, arm 2 itself is recognized, and with respect to arm 1, arm 1 itself, arm 2, weight 12, and connecting rod 13 are recognized. The above-mentioned moment-by-moment posture information and conveyance weight are input to the moment of inertia calculation means 18, and the moment of inertia calculation means 18 calculates the moment of inertia ( (about the y-axis in the coordinate system shown in FIG. 4), and based on this, the gain calculation means 19 and 20
The velocity feedback gains _Gv1 and _Gv2 are calculated at each moment. These velocity feedback gains G _v1 and G _v2 can be expressed in general form as follows: G _v1 = f ₁ (J ₁ )...(2) G _v2 = f ₂ (J ₂ )...(3) However, f ₁ , f ₂ : Function, J ₁ , J ₂ : Moment of inertia of the driven parts of motors 4 and 5, J ₁ ,
J ₂ is calculated moment by moment by the moment of inertia calculation means 18, and based on this moment of inertia J ₁ and J ₂ , G _v1 ,
G _v2 is required every moment. These velocity feedback gains G _v1 and G _v2 are input to the arm controller 21 and the arm controller 22, and via the arm controllers 21 and 22, the blocks shown in FIG. As G _v in the figure,
Momentarily changing velocity feedback gains _Gv1 and _Gv2 are provided to control the motion of arms 1 and 2. In addition, the conveyed weight calculation means 16,
Attitude calculation means 17, moment of inertia calculation means 1
8. Gain calculating means 19 and 20 constitute speed feedback gain calculating means 23.

Figure 3 shows the results of controlling the _drive of the arm using this control device.
Figure 3b is an example where the arm trajectory is changed to 360° and the locus is fixed, and the vertical width is changed to 0, +300, +500 mm, and the arm lengths are _{1 2} = 1000 and _{2 8} = 800 mm. shows the results of controlling θ ₁ to a predetermined value, and good results were obtained in both cases.

Note that in this example, a two-joint arm was explained to simplify the explanation, but the effect is greater with a multi-joint mechanism, and the same method can be applied to three-dimensional movements as well. Needless to say.

Further, although the present embodiment has been described using a molten metal supply device as an example, it goes without saying that the present invention can be applied to various conveyance devices that automatically supply materials.

〔Effect of the invention〕

As explained above, according to the control device for the conveyance device according to the present invention, the driven target including the ladle and the conveyance arm is The moment-by-moment moment of inertia of the transport arm is determined, the speed feedback gain is determined moment-by-moment based on the moment-by-moment moment of inertia, and the movement of the transfer arm is controlled by the speed feedback gain obtained. Therefore, the speed feedback gain changes in accordance with the change in the moment of inertia of the driven part, and it is possible to always obtain suitable control characteristics of the transport operation even if the transport weight or the transport trajectory is changed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of a control device for a conveying device according to the present invention, FIG. 2 is a block diagram showing a feedback operation of this control device, and FIGS. 3 a and b show different versions of this control device. A control characteristic diagram, FIG. 4 is a side view showing a molten metal supply device as an example of a conventional conveying device, and FIGS.
Fig. 6 is a characteristic diagram showing changes in the moving speed of the rotation center of the ladle, Fig. 7 is a block diagram showing a conventional feedback operation, Fig. 8 is a control characteristic diagram of a conventional control device, and Fig. 9 is a characteristic diagram of the present invention. A side view showing changes in the conveyance trajectory due to changes in the position of the spout in the device;
FIG. 10 is a side view showing a possible conveyance trajectory in the apparatus of the present invention when there are no obstacles. 1, 2... Arm, 3... Ladle, 4, 5, 6
... Drive motor, 7, 8, 9 ... Rotary encoder, 16 ... Transport weight calculation means, 17 ... Attitude calculation means, 18 ... Moment of inertia calculation means, 1
9, 20...Gain calculation means, 23...Speed feedback gain calculation means.

Claims (1)

[Scope of Claims] 1. In a control device for a conveyance device that controls the operation of a conveyance arm that conveys a ladle using a speed feedback gain, the amount of conveyed material being pumped into the ladle is determined based on the metering angle of the ladle. transport weight calculating means for determining the weight and adding the weight of the ladle itself to the calculated weight of the transported material to obtain the transport weight; and posture calculating means for calculating the momentary posture of the transport arm based on the rotation angle of the transport arm. and, based on the conveyance weight determined by the conveyance weight calculation means and the instantaneous posture of the conveyance arm determined by the posture calculation means, the instantaneous moment of inertia of the driven part including the ladle and the conveyance arm is determined. A control device for a conveying device, comprising: a moment of inertia calculation means; and a gain calculation means for calculating the speed feedback gain from moment to moment based on the moment of inertia calculated by the moment of inertia calculation means.