JPH0785163B2 - Drive controller for X-ray quick-copy device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive control device for controlling conveyance and stop of a film holder in an X-ray quick-shooting device equipped on a cassette-type X-ray fluoroscopic imaging stand, and more particularly, The present invention relates to a drive control device for an X-ray radiography apparatus capable of accurately stopping and positioning a film holder.

2. Description of the Related Art As shown in FIG. 3, in a cassette-type X-ray fluoroscopic imaging table, a table 1 and a X-ray tube device 3 are supported by a supporting table 1, and the table supporting frame 2 supports an object to be examined. A top plate 5 on which the 4 is laid is provided so as to be movable in the vertical and horizontal directions. An image system device is provided on the side facing the X-ray tube device 3 with the top plate 5 interposed therebetween. This video system apparatus includes a cassette-less X-ray rapid copying apparatus 6 for recording an X-ray image on an image recording medium such as a film, an image intensifier 7 for converting the X-ray image into a visible light image,
It is composed of an X-ray television camera 8 which captures this output fluorescent image. Here, the X-ray rapid copying apparatus 6 takes out the unphotographed films stored in a supply magazine (not shown) in large numbers one by one from the supply magazine, inserts them into the film holder 9, and operates the switch by the operator. The film holder 9 is conveyed from the standby position F to the photographing position R, and after the X-ray imaging of the subject 4 is completed, the film holder 9 is returned to the standby position F again, and the photographed film is taken out from the film holder 9. A series of operations for storing in a storage magazine (not shown) is performed.

As shown in FIG. 4, the quick-shooting drive mechanism for carrying the film holder 9 has a DC servomotor 10 as a drive source, and a pulley 12 is attached to an output shaft 11 thereof. A conveyor belt 14 is laid between 12 and another pulley 13 provided opposite to the conveyor belt 14, and a connector 15 is provided at one position of the conveyor belt 14, and the connector 15 has a connector 15. A film holder 9 is attached.
An encoder 16 that generates a pulse signal according to the rotation of the servo motor 10 is attached to the servo motor 10.

Furthermore, as shown in FIG. 5, the conventional drive control device for controlling the transport and stop of the film holder 9 in such a quick drive mechanism has a first amplifier 17 for amplifying the positional deviation.
, A second amplifier 18 for amplifying the speed deviation, and a drive circuit 19
Load including servo motor 10 and film holder 9
20, position detector 21, speed detector 22, and first comparator
It has a 23 and a second comparator 24 and is a servo mechanism using a feedback control method. In FIG. 5, reference symbol Tf is a disturbance such as a frictional force received by the film holder 9.

Next, the operation of such a conventional drive control device will be described. First, the film holder 9 is placed in the standby position F shown in FIG.
From the target to the photographing position R and stop, and the target position θr for the stop is input. Then, the servo motor 10 is driven and the film holder 9 starts moving along a predetermined transport path. At this time, the pulse signal output from the encoder 16 shown in FIG. 4 is input to the position detector 21 to detect the current position θ ₀ of the film holder 9, and the value of the current position θ ₀ is the speed detection value. The current speed v ₀ is detected from the difference from the previous position by inputting it to the device 22. Next, the current position θ ₀ of the film holder 9 is input to the first comparator 23 and is compared and calculated with the target position θr to obtain the position deviation Δθ. This position deviation Δθ is multiplied by the position gain in the first amplifier 17 to obtain the speed command value v. Next, the speed command value v is input to the second comparator 24 and is compared with the current speed v ₀ obtained by the speed detector 22 to obtain the speed deviation Δv. The speed deviation Δv is multiplied by the speed gain in the second amplifier 18 to obtain the motor drive signal D. The motor drive signal D is input to the servo motor 10 via the drive circuit 19 and drives the servo motor 10 in proportion to the magnitude of the motor drive signal D. As a result, the film holder 9 as the load 20 moves toward the photographing position R in FIG. Then, while negatively feeding back the current position θ ₀ of the film holder 9 in this manner, the position deviation Δθ between the target position θr and the current position θ ₀ is obtained, and the above operation is performed until the position deviation Δθ becomes zero. repeat. As a result, the film holder 9 is positioned and stopped at the photographing position R. The same operation is performed when the image pickup position R is conveyed to the standby position F and stopped. This is a position control system of the proportional control which is generally performed. Here, in the servo mechanism shown in FIG. 5, a microcomputer is used to enclose the target position θr, calculate the position deviation Δθ, calculate the speed deviation Δv, and perform the servo processing of the output of the motor drive signal D by enclosing it with a broken line. It is considered to be a software servo that operates on a program.

The procedure of the servo processing for each sampling time of the software servo is shown in the flowchart of FIG.

However, such a conventional drive control device for an X-ray radiography apparatus is a position control system of proportional control, and when the film holder 9 approaches the target position θr, the position deviation Δθ becomes small, and such a small position deviation is generated. Even if Δθ is amplified by the first amplifier 17, the resulting speed command value v does not become so large, so the speed deviation Δv also becomes small, which is
Also, the motor drive signal D obtained by amplifying the signal was not increased. Therefore, the film holder 9 is set at
In the state of approaching r, the output of the servomotor 10 was small.

However, as shown in FIG. 4, the film holder 9 is
Since it moves between the guide members 25, 25 by means of rollers or rollers, there is much sliding friction and backlash, and these frictional forces and backlash act as disturbance Tf in FIG. Then, due to the action of the disturbance Tf, the output of the servo motor 11 which has decreased as described above is consumed by the disturbance Tf, and the film holder 9 as the load 20 may not be moved to the target position θr. . Therefore, the accuracy of the stop position of the film holder 9 is deteriorated. From this fact, the X-ray images to be photographed on the film may be misaligned on the film one by one, or between the film holder 9 and the supply magazine or the storage magazine at the standby position F. There was a problem that the delivery was not successful.

Therefore, it is an object of the present invention to provide a drive controller for an X-ray radiography apparatus that can solve such problems.

Means for Solving the Problems The means of the present invention for solving the above problems is to compare the target position and the current position of the film holder that is conveyed and stopped between the standby position and the photographing position. In the drive controller of the X-ray radiography apparatus for controlling the positioning of the film holder, the speed controller has a means for obtaining the deviation and a means for obtaining the speed deviation by comparing the speed command value with the current speed. A means for integrating the speed deviation is provided in parallel with a means for proportionally amplifying the deviation, and a means for judging the transport or stop state of the film holder is provided at a stage before these, and the film is judged by the state judgment of the judging means. The position control of the cage is performed by a drive control device of the X-ray radiography apparatus, which is proportional control during conveyance and is switched to proportional integration control when stopped.

Embodiment Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a control block diagram showing an embodiment of a drive control device for an X-ray radiography apparatus according to the present invention. This drive control device is the same as that shown in FIG. 3 in the X-ray radiography device 6 equipped on the cassette-less X-ray fluoroscopic imaging table.
Positioning control for transporting and stopping the film holder 9 in a quick-shooting drive mechanism configured similarly to that shown in FIG. 4 is performed. A first amplifier 17, a second amplifier 18, a drive circuit 19, It has a servomotor 10, a load 20 including a film holder 9, a position detector 21, a speed detector 22, a first comparator 23, and a second comparator 24, and has a feedback control system. It is considered to be a servo mechanism using.

The position detector 21 detects the current position θ ₀ of the transport and stop of the film holder 9 shown in FIG. 4, and is an encoder that generates a pulse signal according to the rotation of the servo motor 10 shown in FIG. It consists of a counter circuit that counts 16 output signals. The speed detector 22 detects the current speed v ₀ of the transport of the film holder 9, and inputs the value of the current position θ ₀ from the position detector 21 and calculates the difference from the previous position, It is divided by the sampling time and differentiated. The first comparator 23 serves as means for comparing the target position of transporting and stopping the film holder 9 with the current position to obtain the positional deviation Δθ, and is the standby position of the film holder 9 shown in FIG. The target position θr at the time of transporting from F to the photographing position R and stopping is input, the current position θ ₀ obtained by the position detector 21 is input, the difference between them is calculated, and the position deviation Δθ is output. It is like this. The first amplifier 17 generates a speed command value v for the film holder 9 and is adapted to multiply the output position deviation Δθ by a position gain and perform proportional amplification. The second comparator 24 serves as means for comparing the speed command value for the film holder 9 with the current speed to obtain the speed deviation Δv, and inputs the speed command value v from the first amplifier 17. At the same time, the current speed v ₀ obtained by the speed detector 22 is input, the difference between the two is calculated, and the speed deviation Δv is output. The second amplifier 18 generates a motor drive signal D for the servo motor 10, and is adapted to multiply the output speed deviation Δv by a speed gain and perform proportional amplification. The drive circuit 19 inputs the generated motor drive signal D and actually drives the servomotor 10. In addition, in FIG.
Tf is a disturbance such as a frictional force received by the film holder 9.

Here, in the present invention, an integrator 26 is provided in parallel with the second amplifier 18 as a means for proportionally amplifying the speed deviation Δv output from the second comparator 24, and the integrator 26 is provided in the preceding stage. A state discriminator 27 is provided. The integrator 26 uses the speed deviation Δ output from the second comparator 24.
This is a means for inputting and integrating v, and by sequentially adding speed deviations Δv calculated at each sampling time, even small speed deviations Δv are output as large values. Further, the state discriminator 27 serves as a means for discriminating whether the film holder 9 is being conveyed or is stopped, and a state judgment flag is provided for each sampling time to determine which state the film holder 9 is in. To determine. Then, when the film holder 9 is being conveyed between the standby position F and the photographing position R, the speed deviation Δv is proportionally amplified only by the second amplifier 18 to obtain the position control of the proportional control. Alternatively, when the vehicle is stopped at the standby position F, the speed deviation Δv is integrated and compensated by the integrator 26 and switched to the position control of the proportional integral control.

As described above, the position control system is switched between the proportional control and the proportional-integral control depending on the state of the film holder 9 determined by the state determiner 27. The integral compensation calculation is always performed by the integrator 26 to further improve the position accuracy. When the proportional-plus-integral control is performed by executing the operation, the software servo is surrounded by a broken line in FIG. 1 and the processing capacity of the microprocessor in the standard 8-bit microcomputer is limited.
This may interfere with other servo processing performed in parallel and processing when an error occurs. On the contrary,
By lengthening the sampling interval of servo processing,
Although it is possible to prevent other processing and the like from being hindered, in this case, the control performance is lowered. Therefore, a standard 8-bit microcomputer is used by performing the integral compensation calculation by using the integrator 26 and executing the proportional-plus-integral control only when the film holder 9 having a sufficient time for the arithmetic processing is stopped. The software servo mechanism also performs control with high positional accuracy.

Next, the operation of the drive control device of the present invention thus configured will be described with reference to the flowchart of FIG. 2 showing the processing procedure of the software servo enclosed by the broken line in the servo mechanism shown in FIG. . First, it is assumed that the film holder 9 is conveyed from the standby position F shown in FIG. 4 to the photographing position R and stopped, and the target position θr for the stop is input. Then, the servo motor 10 is driven to drive the film holder 9
Starts moving on a predetermined transport path. At this time, a pulse signal is output from the encoder 16 shown in FIG. 4 according to the rotation of the servo motor 10. Then, this pulse signal is input to the position detector 21 and counted to obtain the current position θ ₀ of the film holder 9 (step). Further, the value of the current position θ ₀ is input to the speed detector 22 and 1
The difference from the value of the current position before the sampling time is calculated and divided by the sampling time to obtain the film holder 9
The current speed v _{0 of} is calculated (step). Next, the calculated current position θ ₀ is input to the first comparator 23. The target position θr is also input to the first comparator 23,
The position deviation Δθ (= θr−θ ₀ ) is calculated by comparing the two.
(Step). Next, this position deviation Δθ is
Input to the first amplifier 17, the position gain is multiplied by the first amplifier 17, and the speed command value v for the film holder 9 is input.
Is generated. Next, the generated speed command value v is
Input to the second comparator 24. The current speed v ₀ is also input to the second comparator 24, and the speed deviation Δv (= v−v ₀ ) is calculated by performing a comparison calculation between the two (step).

Next, in this state, the state discriminator 27 determines whether or not the sheet is being conveyed (step). Since the film holder 9 is in the process of moving from the standby position F to the photographing position R, the step advances to the "YES" side. At this time, the state discriminator 27 discriminates by, for example, the state determination flag “1”,
The speed deviation Δv output from the second comparator 24 is input only to the second amplifier 18. Then this second amplifier 18
Generates a motor drive signal D and outputs it by multiplying the speed deviation Δv by a speed gain and proportionally amplifying it (step). The motor drive signal D is input to the servo motor 10 via the drive circuit 19 and drives the servo motor 10 in proportion to the magnitude of the motor drive signal D. As a result, the film holder 9 as the load 20 moves toward the photographing position R in FIG. Then, while negatively feeding back the current position θ ₀ of the film holder 9 as described above,
The position deviation Δθ between the target position θr and the current position θ ₀ is calculated, and the above operation is repeated until the position deviation Δθ becomes zero.

Next, when the film holder 9 reaches the photographing position R and is stopped by repeating steps 1 to 3 in this manner, the step proceeds to the "NO" side. At this time, the state discriminator 27 discriminates by, for example, the state determination flag “0”,
The speed deviation Δv output from the second comparator 24 is input to the second amplifier 18 to be proportionally amplified and also input to the integrator 26. Then, the integrator 26 sequentially adds and integrates the speed deviation Δv calculated for each sampling time (step), and outputs a large value even if the speed deviation Δv is small. Next, the integrated value of the speed deviation Δv is added to the output value which is proportionally amplified by the second amplifier 18 (step). Then, the addition result is output as the motor drive signal D (step). Next, this motor drive signal D is input to the servo motor 10 via the drive circuit 19,
Servo motor in proportion to the magnitude of the motor drive signal D
Drive 10 and stop when it matches the target position θr.
At this time, the motor drive signal D becomes larger than before due to the integral compensation calculation by the integrator 26, and the servo motor 10
Makes a more sensitive response and can position the film holder 9 without being affected by the disturbance Tf.

The same operation is performed when the film holder 9 is conveyed from the photographing position R toward the standby position F and stopped.

EFFECTS OF THE INVENTION Since the present invention is configured as described above, the position control of the film holder 9 is performed by the state determination of the state determination device 27, the proportional control is performed while the film holder 9 is being conveyed, and the proportional integral control is performed when the film holder 9 is stopped. It can be switched. Then, in the proportional-plus-integral control, the integral value of the speed deviation Δv is obtained and added to the proportional amplification value to generate the motor drive signal D, so that the value can be made larger than in the conventional case. Therefore, even when the film holder 9 is close to the target position θr, the output of the servo motor 10 is large, and the response is more sensitive and the influence of the disturbance Tf such as the friction force is not exerted.
The film holder 9 can reach the target position θr. That is, the stop positioning of the film holder 9 can be performed with high accuracy. As a result, the X-ray image to be photographed on the film will not be displaced on each film, and the film can be smoothly transferred between the film holder 9 and the film magazine at the standby position F. I can do it.

In addition, since the proportional-plus-integral control is executed only when the film holder 9 is stopped by the state discrimination by the state discriminator 27, the control performance is improved even in software servo using a standard 8-bit microcomputer. can do. Therefore, it is economical because it is not necessary to use a microcomputer having a larger number of bits and a larger computing capacity.

[Brief description of drawings]

FIG. 1 is a control block diagram showing an embodiment of a drive controller for an X-ray radiography apparatus according to the present invention, FIG. 2 is a flow chart showing a processing procedure of software servo surrounded by a broken line in FIG. 1, and FIG. FIG. 4 is a schematic view showing a cassette-type X-ray fluoroscopic imaging table, FIG. 4 is an explanatory view showing a quick-shooting drive mechanism for carrying the film holder in the X-ray quick-shooting device, and FIG.
FIG. 6 is a control block diagram showing a drive control device of a conventional X-ray radiography apparatus, and FIG. 6 is a flowchart showing a processing procedure of software servo surrounded by a broken line in FIG. 6 ... X-ray speed recorder, 9 ... Film holder, 10 ... Servo motor, 17 ... First amplifier, 18 ... Second amplifier (means for proportionally amplifying speed deviation), 19 ... Drive Circuit, 20
...... Load, 21 …… Position detector, 22 …… Speed detector, 23 ・ ・ ・
… First comparator (means for comparing the target position with the current position to obtain the position deviation), 24 …… Second comparator (means for comparing the speed command value with the current speed to obtain the speed deviation) , 26 ...
... integrator (means for integrating velocity deviation), 27 ... status determiner (means for determining the state of transport and stop of the film holder), θr ... target position, θ ₀ ... current position, Δθ ...
Position deviation, v ... speed command value, v ₀ ... current speed, Δv ...
… Velocity deviation, D …… Motor drive signal.

Claims (1)

[Claims] 1. A means for comparing a target position of a film holder, which is conveyed and stopped between a standby position and a photographing position, with a current position to obtain a position deviation, and a speed command value and a current speed. In a drive control device of an X-ray radiography apparatus which has a means for comparing and obtains a speed deviation, and a means for integrating the speed deviation in parallel with the means for proportionally amplifying the speed deviation. And a means for determining the state of transport and stop of the film holder at the preceding stage, the position control of the film holder by the state determination of this determination means, and the proportional control during transport,
A drive control device for an X-ray radiography device, which is characterized by switching to proportional-integral control when stopped.