JP2023154362A - Flow rate control system, intravenous drip system, infusion pump, flow rate control method and program - Google Patents

Abstract

To provide a flow rate control system and the like which can accurately and stably control a flow rate of droplets dropping from a nozzle while suppressing an arithmetic load.SOLUTION: A flow rate control system comprises: an imaging device which images droplets; a volume calculation unit which calculates the volume of droplets on the basis of image data of the droplets; a target cycle calculation unit which calculates a target dropping cycle on the basis of the set target flow rate and the volume of the droplets calculated by the volume calculation unit; and a dropping cycle adjustment unit which performs flow rate adjustment such that a measurement value of the dropping cycle gets close to the target dropping cycle. The system calculates the volume of first droplets for the droplets dropping from the nozzle after the start of intravenous drip, performs first feedback control to the dropping cycle on the basis of the first target dropping cycle calculated on the basis of the volume, calculates the volume of second droplets for the droplets dropping from the nozzle after the dropping cycle becomes stable, and performs second feedback control to the dropping cycle on the basis of the second target dropping cycle calculated on the basis of the volume.SELECTED DRAWING: Figure 1

Description

The present invention relates to a flow rate control system for liquid dripping from a nozzle, a drip system, an infusion pump, a flow rate control method, and a program.

When injecting liquids (intravenous fluids) such as medical solutions and nutrients, it is important to maintain a predetermined flow rate. Conventionally, drip flow rate control involves counting the number of droplets dripping into the drip tube, assuming that the volume of droplets dripping from a nozzle with the same diameter is constant, and calculating the flow rate from the number of drops per unit time. This is done by calculating and adjusting the droplet dropping period (dropping time interval).

However, in reality, the surface tension of a droplet varies depending on conditions such as the type of liquid (viscosity) and the environmental temperature, so the volume of each droplet is not constant. Furthermore, in a medical setting, a patient may change his or her posture during an infusion, and in this case, the head difference of the infusion fluid may change, causing the volume of the droplet to fluctuate. Therefore, in the conventional method of controlling the flow rate only by the droplet dropping period, it is difficult to control the flow rate with high accuracy.

In recent years, techniques have been known in which a droplet falling from a nozzle is imaged and the volume of the droplet is calculated based on the image of the droplet (for example, see Patent Documents 1 to 3). Furthermore, Patent Document 3 discloses an infusion pump that sets the flow rate based on the measured droplet volume.

International Publication No. 2017/043437 Japanese Patent Application Publication No. 2018-148962 JP2011-62371A

The inventors conducted experiments to measure the volume of droplets dripping from nozzles under various conditions based on images, and found that even when the same type of liquid is dripped from nozzles with the same diameter, , discovered that the droplet volume changes depending on the dropping period. This fact means that the volume per droplet fluctuates not only due to factors such as the type of liquid and the environment, but also when the dropping cycle is adjusted for flow rate control. In other words, since the dropping period and the volume of the droplet are correlated with each other, it is difficult to accurately control the flow rate using the conventional flow rate control method based on the dropping period.

On the other hand, it is possible to precisely control the flow rate by adjusting the drop cycle while continuously measuring the volume of each drop, but in this case, the computational processing load involved in controlling the flow rate becomes large. Put it away.

An object of the present invention is to provide a flow rate control system, an infusion system, an infusion pump, a flow rate control method, and a program that can accurately control the flow rate of droplets dripping from a nozzle while suppressing the computational processing load. shall be.

In order to solve the above problems, a flow rate control system that is one aspect of the present invention provides a flow rate control system that controls the flow rate of droplets in an intravenous drip system that is provided with a flow rate adjustment unit that changes the flow rate of droplets dripping from a nozzle. The control system includes: an imaging device configured to image a droplet dropping from the nozzle and output image data; and a control system configured to capture a droplet falling from the nozzle based on the image data output from the imaging device. a volume calculation unit configured to calculate the volume of a drop; and a drop detection configured to detect the timing at which a droplet begins to fall away from the nozzle or the number of times a droplet falls away from the nozzle. means, a dropping cycle calculating unit configured to calculate a dropping cycle in which droplets are dropped from the nozzle based on the timing or the number of times, a preset target flow rate, and calculating by the volume calculating unit. a target period calculating section configured to calculate a target dropping period based on the volume of the droplet; a drip cycle adjustment unit configured to control a flow rate adjustment unit, and the target cycle calculation unit calculates the volume of the first droplet calculated for the droplet dropped from the nozzle after the start of infusion. based on the first target dropping cycle, and the dropping cycle adjusting unit adjusts the first target dropping cycle so that the dropping cycle calculated by the dropping cycle calculating unit approaches the first target dropping cycle. The target cycle calculation unit is configured to perform feedback control, and further includes a second droplet volume calculated for the droplet dropped from the nozzle after the dropping cycle is stabilized by the first feedback control. The dripping period adjustment unit further adjusts the dripping period so that the dripping period calculated by the dripping period calculation unit approaches the second target dripping period. 2 is configured to perform feedback control.

In the flow rate control system, the target period calculating unit determines that the dripping period is stabilized when the dripping period calculated during the first feedback control period falls within an error range of 10%; The second target dropping period may be calculated based on the volume of the second droplet calculated for the droplet dropped from the nozzle after making the determination.

In the above flow rate control system, the volume calculating section may be configured to stop calculating the volume of the droplet after the second feedback control is started.

In the above flow rate control system, the dropping period calculation unit further calculates a first target dropping period based on the volume of the droplet calculated for the droplet dropped from the nozzle during execution of the first feedback control. The dropping cycle adjustment unit may be configured to perform first feedback control so as to approach the first target dropping cycle updated by the dropping cycle calculating unit.

In the above flow rate control system, the dripping cycle adjustment unit determines, at the start of infusion, that the dripping cycle calculated by the dripping cycle calculation unit is smaller than the target flow rate and the theoretical droplet volume. The flow rate adjustment unit may be controlled so as to approach the calculated third target dropping period.

In the above flow control system, the drip detection means detects the timing or the number of times based on image data output from the imaging device, has a plurality of light emitting elements, and is configured to illuminate the field of view of the imaging device. and a light source control unit configured to control on/off of the plurality of light emitting elements, and the light source control unit is configured to control the first feedback control after the start of infusion. the plurality of light emitting elements are controlled to be turned on and off so that at least a region of the field of view of the imaging device necessary for detecting the timing and calculating the volume of the droplet is illuminated until the second feedback control is performed. During execution, some of the light emitting elements among the plurality of light emitting elements may be turned off within a range in which a region necessary for detecting the timing in the field of view of the imaging device is illuminated.

In the flow rate control system, the light source control unit further determines that the total amount of light of the light emitting elements emitted during the execution of the second feedback control is the total amount of light of the light emitting elements emitted during the execution of the first feedback control. The amount of light from each light emitting element emitted during execution of the second feedback control may be increased so that the amount of light is approximately the same as the amount of light.

An infusion pump that is another aspect of the present invention includes a tube holding portion configured to hold an infusion tube connected to an infusion tube, and a tube holding portion configured to hold an infusion tube connected to an infusion tube, and a liquid in the infusion tube that is pumped by pressing the infusion tube. a pump unit configured to an operation input unit that receives input of a target flow rate; a volume calculation unit configured to calculate a volume of a droplet falling from the nozzle based on image data output from the imaging device; a droplet detection means configured to detect the timing at which the droplet begins to fall away from the nozzle or the number of times the droplet falls away from the nozzle, and the droplet starts to fall from the nozzle based on the timing or the number of times; A target dropping cycle is calculated based on a dropping cycle calculating unit configured to calculate a dropping cycle, the target flow rate accepted by the operation input unit, and the volume of the droplet calculated by the volume calculating unit. a drip cycle adjustment unit configured to control the pump unit so that the drip cycle calculated by the drip cycle calculation unit approaches the target drip cycle; , the target period calculation unit is configured to calculate a first target dripping period based on a volume of the first droplet calculated for the droplet dropped from the nozzle after the start of infusion. , the drip cycle adjustment unit is configured to perform first feedback control so that the drop cycle calculated by the drop cycle calculation unit approaches the first target drip cycle, and the target cycle calculation unit includes: Further, the second target dropping cycle is calculated based on the volume of the second droplet calculated for the droplet dropped from the nozzle after the dropping cycle is stabilized by the first feedback control. , the dropping cycle adjustment unit is further configured to perform second feedback control so that the dropping cycle calculated by the dropping cycle calculation unit approaches the second target dropping cycle.

Another aspect of the present invention is an infusion system that includes the infusion pump, the infusion tube to which the nozzle is attached, and an infusion tube connected to the infusion tube.

Another aspect of the present invention is a flow rate control method for controlling the flow rate of droplets in an intravenous drip system provided with a flow rate adjustment unit that changes the flow rate of droplets dripping from a nozzle, the method comprising: an imaging step of imaging a droplet falling from a nozzle and outputting image data; and a volume configured to calculate the volume of the droplet falling from the nozzle based on the image data output in the imaging step. a calculating step, a dropping detection step of detecting the timing at which the droplet starts falling away from the nozzle or the number of times the droplet falls away from the nozzle; a dripping period calculation step of calculating a dripping period to be dripped from the nozzle, a preset target flow rate, and a volume of the first droplet calculated for the droplet dripped from the nozzle after the start of dripping; a first target period calculation step of calculating a target dripping period of 1; and a first target period calculation step of feedback controlling the flow rate adjustment unit so that the dripping period calculated in the dripping period calculation step approaches the first target dripping period. based on the dropping cycle adjustment step, a preset target flow rate, and the volume of the second droplet calculated for the droplet dropped from the nozzle after the dropping cycle is stabilized by the first flow rate adjustment step. a second target cycle calculation step for calculating a second target drop cycle; and feedback control of the flow rate adjustment unit so that the drop cycle calculated in the drop cycle calculation step approaches the second target drop cycle. A second dropping period adjustment step is included.

Another aspect of the present invention is a program that causes a computer to execute an infusion system including a flow rate adjustment section that changes the flow rate of droplets dripping from a nozzle. an image data acquisition step of acquiring the image data from an imaging device that takes an image and outputs the image data, and calculating the volume of the droplet falling from the nozzle based on the image data acquired in the image data acquisition step. a drop detection step of detecting the timing at which a droplet starts to fall away from the nozzle or the number of times the droplet falls away from the nozzle; , a dropping cycle calculation step of calculating a dropping cycle in which droplets are dropped from the nozzle, a preset target flow rate, and a first droplet volume calculated for the droplets dropped from the nozzle after the start of dripping. a first target cycle calculation step of calculating a first target drop cycle based on the flow rate adjustment unit so that the drop cycle calculated in the drop cycle calculation step approaches the first target drop cycle; a first dripping cycle adjustment step that performs feedback control; a preset target flow rate; and a second droplet calculated for the droplets dropped from the nozzle after the dropping cycle is stabilized by the first flow rate adjustment step. a second target cycle calculation step of calculating a second target drop cycle based on the volume of the drop; and a second target cycle calculation step in which the drop cycle calculated in the drop cycle calculation step approaches the second target drop cycle A second drip cycle adjustment step of feedback controlling the flow rate adjustment section is executed.

According to the present invention, it is possible to accurately control the flow rate of droplets dripping from a nozzle while suppressing the computational processing load.

1 is a diagram showing a schematic configuration of a drip system including a flow control system according to an embodiment of the present invention. FIG. 2 is a schematic diagram showing a schematic configuration of the light source shown in FIG. 1. FIG. 2 is a schematic diagram for explaining the positional relationship between a light source and a nozzle shown in FIG. 1. FIG. 2 is a block diagram showing a schematic configuration of the information processing device shown in FIG. 1. FIG. It is a graph showing changes in the volume of droplets (physiological saline) depending on the dropping cycle. It is a graph showing a change in the volume of a droplet (sugar solution) depending on the dropping cycle. It is a graph showing changes in the volume of droplets (ultrapure water) depending on the dropping period. 1 is a flowchart schematically showing the operation of a flow control system according to an embodiment of the present invention. It is an image for explaining control of a light source in a flow rate control method according to an embodiment of the present invention. It is an image for explaining control of a light source in a flow rate control method according to an embodiment of the present invention. It is a graph which shows the startup curve in flow control by 1st Example. 3 is a graph showing a trumpet curve (0 to 120 minutes) in flow rate control according to the first example. 3 is a graph showing a trumpet curve (60 to 120 minutes) in flow rate control according to the first example. It is a graph which shows the startup curve in flow control by 2nd Example. 7 is a graph showing a trumpet curve (0 to 120 minutes) in flow rate control according to the second example. 7 is a graph showing a trumpet curve (60 to 120 minutes) in flow rate control according to the second example.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A flow control system, an infusion system, an infusion pump, a flow control method, and a program according to embodiments of the present invention will be described below with reference to the drawings. Note that the present invention is not limited to these embodiments. In addition, in the description of each drawing, the same parts are denoted by the same reference numerals.

The drawings referred to in the following description only schematically illustrate shapes, sizes, and positional relationships to the extent that the contents of the present invention can be understood. That is, the present invention is not limited to the shapes, sizes, and positional relationships illustrated in each figure. Furthermore, drawings may include portions with different dimensional relationships and ratios.

(Flow control system configuration)
FIG. 1 is a diagram showing a schematic configuration of an infusion system including a flow control system according to an embodiment of the present invention. FIG. 1 shows an example in which a flow rate control system 10 according to the present embodiment is applied to an infusion system 1 that drips a liquid (intravenous fluid) filled in an infusion bag 2. The infusion system 1 includes an intermediate tube 3 connected to an infusion bag 2, an infusion tube 4, and an infusion tube 5, and a nozzle 6 is installed inside the infusion tube 4.

The infusion bag 2 is a container filled with an intravenous solution such as a medical solution or a nutritional supplement, and is suspended and held on a support stand or the like during infusion. The intermediate tube 3 is connected at one end to the drainage port 2a of the infusion bag 2, and at the other end to one end of a nozzle 6 attached to the upper lid 4a of the drip barrel 4. The other end of this nozzle 6 is provided so as to protrude into the drip tube 4.

The infusion tube 5 is made of an elastic material, and by changing the pressure that presses a part of the infusion tube 5 in the radial direction (in other words, the diameter of the infusion tube 5), the flow rate of the liquid flowing through the infusion tube 5 can be adjusted. Change. Furthermore, by squeezing a portion of the infusion tube 5, the liquid within the infusion tube 5 can be delivered. When the flow rate of the liquid flowing through the infusion tube 5 changes, the internal pressure of the drip tube 4 changes, and the dropping period of the droplets 7 dropped from the nozzle 6, that is, the flow rate of the liquid per unit time changes.

The infusion tube 5 is held by a flow rate adjustment section 8. The flow rate adjustment section 8 includes a holding member (tube holding section) that can hold the flexible infusion tube 5 while maintaining its shape, and a control valve 9 that can press the infusion tube 5 in the radial direction. It is provided. The control valve 9 is driven under electrical control by the information processing unit 100 and changes the pressing force against the infusion tube 5.

Further, the flow rate adjustment section 8 may be provided with a pump section for feeding the liquid flowing through the infusion tube 5. The configuration of the pump section is not particularly limited. For example, the pump unit may employ a roller system that presses a portion of the infusion tube 5 by rotating a roller, or a plurality of fingers (peristaltic fingers) may be used to press a portion of the infusion tube 5. A finger method of sequentially pressing may be used.

The flow control system 10 is a system that controls the flow rate of droplets 7 that are intermittently dropped from the nozzle 6 (in other words, the flow rate of the liquid flowing through the infusion tube 5), and includes a camera 12 and an information processing unit 100. The camera 12 is configured to image droplets dropping from the nozzle 6 and output image data. The information processing unit 100 is configured to take in image data output from the camera 12 and execute various calculations for controlling the flow rate of droplets based on the image data. An operation input section 110 and a display section 120 may be connected to the information processing section 100. Further, the flow control system 10 may include a light source 11 arranged to face the camera 12 with the nozzle 6 in between and configured to illuminate the field of view of the camera 12.

Furthermore, in addition to the information processing section 100, the operation input section 110, and the display section 120, the infusion pump 20 can be configured by housing the flow rate adjustment section 8 provided with a pump section in one housing. . In this case, the infusion pump 20 may be provided with ports for connecting the camera 12 and the light source 11, respectively. Furthermore, the imaging unit may be configured by housing the camera 12 and the light source 11 in one housing, and in this case, the infusion pump 20 may be provided with a port for connecting the imaging unit. Alternatively, the light source 11, the camera 12, the information processing section 100, the operation input section 110, and the display section 120 are housed in one housing, and a pump section is provided in this housing via a cable or the like to adjust the flow rate. Section 8 may also be connected.

FIG. 2 is a schematic diagram showing a schematic configuration of the light source 11. As shown in FIG. FIG. 3 is a schematic diagram for explaining the positional relationship between the light source 11 and the nozzle 6. Of these, FIG. 2 shows the front (light emitting surface) of the light source 11, and FIG. 3 shows the side of the light source 11. In both FIGS. 2 and 3, only the main structure of the light source 11 is shown, and the housing and the like are omitted.

As the light source 11, for example, a surface light source including a light emitting element such as an LED (Light Emitted Diode) can be used. The light source 11 shown in FIG. 2 includes a plurality of light emitting elements L mounted on a substrate SB on which a circuit is formed. In the light source 11 shown in FIG. 2, the light emitting elements L are arranged in 5 columns and 6 rows. As shown in FIG. 3, the light source 11 is preferably arranged such that its longitudinal direction is the vertical direction so that it can widely illuminate the vertical direction in which the droplet 7 falls.

The substrate SB is provided with a light control unit CL that switches or adjusts the lighting states of the plurality of light emitting elements L. The light control unit CL switches on (lighting on)/off (lighting out) for each element or for each element group including one or more elements (for example, for each row) under the control of the information processing unit 100 described later. Further, the light control unit CL adjusts the voltage applied to each light emitting element L to change the amount of light (light control value). Examples of the dimming method include an 8-bit PWM dimming method (0 to 255 gradations). Note that in order to suppress flicker in images captured by the camera 12, it is preferable to set the PWM frequency higher than the imaging frame rate of the camera 12.

In this embodiment, as shown in FIG. 3, among the six rows of light emitting elements L, the light emitting elements L in the two central rows 11c and 11d illuminate the nozzle tip 6a and its vicinity. The arrangement of the light source 11 has been determined. When the nozzle 6 and the light source 11 are arranged in this way, for example, when all the light emitting elements L in the rows 11a to 11f are turned on, the entire droplet 7 hanging from the nozzle 6 and the nozzle tip 6a, or It is possible to illuminate a wide range including the droplet 7 falling away from the nozzle tip 6a. Furthermore, when the light-emitting elements L in rows 11a, 11b, 11e, and 11f are turned off and only the light-emitting elements L in rows 11c and 11d are turned on, droplets 7 are emitted from the nozzle 6 centering around the nozzle tip 6a. It is possible to illuminate the area necessary for detecting the timing at which the liquid begins to separate and fall (hereinafter also referred to as the timing at which the liquid runs out).

However, the configuration of the light source applicable to the flow rate control system 10 is not limited to that shown in FIG. 2. For example, a point light source may be used and an optical system such as a filter or lens may be provided to control the light distribution so that the light emitted from the point light source becomes parallel light. Further, the power source for driving the light source 11 may be a battery or an AC power source.

The camera 12 is an imaging device that includes an imaging device 12a such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor), and is capable of capturing moving images at a predetermined imaging frame rate. The image sensor 12a receives light (subject image) that is incident on the camera 12 and formed into an image by the optical system on its light receiving surface, and generates an electrical signal by performing photoelectric conversion. The camera 12 performs predetermined signal processing such as amplification and A/D conversion on this electrical signal to generate and output image data.

The specifications of the camera 12 are not particularly limited as long as they can obtain an imaging frame rate and resolution sufficient to detect the timing of droplets dropping from the nozzle 6 and measure the volume of the droplets. As an example, in order to be able to image the drip tube 4 from a short distance and not interfere with the user's drip operation, the camera 12 has an outer diameter of a camera module of about several mm to more than 10 mm, and a focal length of the camera module. A small camera with a diameter of several mm to several tens of mm can be used. Further, as the camera 12, a general-purpose product including an image sensor having a number of pixels per side of about (320 to 600) x (480 to 800) and a total number of pixels of 500,000 or less can be used. The imaging frame rate of the camera 12 may be in the range of about 30 to 120 fps (frame rate/second).

Such a camera 12 is installed so as to cover the nozzle tip 6a and a predetermined range below from the nozzle tip 6a. Further, the camera 12 may be provided with an object-side telecentric lens so as to be able to cope with changes in the work distance WD.

The information processing unit 100 is a device having a calculation unit such as a CPU (Central Processing Unit) and a memory, as described later, and may be a general-purpose information processing device such as a personal computer (PC), a notebook PC, or a tablet terminal, or a dedicated information processing unit. It can be configured by a configured microcomputer.

The operation input unit 110 is configured with input devices such as input buttons, switches, numeric keys, keyboards, mice, touch panels, etc., and receives input signals according to operations performed by the user, and inputs them to the calculation unit 150. Operations performed on the operation input unit 110 include inputting a set value of the drip flow rate (target flow rate), an operation to start or end the drip, an operation to start or end imaging with the camera 12, etc. .

The display unit 120 is configured with a liquid crystal display, an organic EL display, or the like, and displays information such as the set value and measured value of the drip flow rate under the control of the information processing unit 100.

FIG. 4 is a block diagram showing a schematic configuration of the information processing section 100. As shown in FIG. 4, the information processing section 100 includes an external interface 130, a storage section 140, and a calculation section 150.

The external interface 130 inputs and outputs signals and inputs image data to and from various devices such as the control valve or pump unit provided in the flow rate adjustment unit 8, the light source 11, the camera 12, the operation input unit 110, and the display unit 120. This is an interface that accepts etc.

The storage unit 140 is configured using a computer-readable storage medium such as a semiconductor memory such as a ROM or a RAM, or a disk drive. The storage unit 140 stores an operating system program, a driver program, a program for causing the information processing unit 100 to execute a predetermined operation, and various data and parameters used during execution of the program.

Specifically, the storage unit 140 includes a program storage unit 141 that stores a program for controlling the flow rate of droplets 7 dripping from the nozzle 6, and an image data storage unit 142 that stores image data output from the camera 12. and a set value storage unit 143 that stores various set values such as the target flow rate of the droplet 7.

The calculation unit 150 is configured using hardware such as a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), and a DSP (Digital Signal Processor), and reads and executes a program stored in the program storage unit 141. By doing so, it transfers data and gives instructions to each section of the information processing section 100, thereby controlling the operation of the information processing section 100 in an integrated manner. Furthermore, based on the image data acquired from the camera 12, the calculation unit 150 monitors the timing at which the droplet 7 dropped from the nozzle 6 runs out, measures the volume of the droplet 7, and uses the volume to Performs calculation processing to control the flow rate of the droplets. Specifically, the functional units realized when the calculation unit 150 executes the droplet measurement program include an imaging control unit 151, an image processing unit 152, a dropping cycle calculation unit 153, and a target cycle calculation unit 154. , a dropping cycle adjustment section 155, and a light source control section 156.

The imaging control unit 151 controls the start and end of imaging for the camera 12, and also controls the operation of the camera 12 to perform imaging at a predetermined imaging frame rate.

The image processing unit 152 performs various image processing based on the image data output from the camera 12. Specifically, the image processing section 152 includes an image generation section 152a, a drip detection section 152b, and a volume calculation section 152c.

The image generation unit 152a performs predetermined image processing such as demosaicing, white balance processing, and gamma correction on the image data sequentially input from the camera 12, thereby generating a photograph of the droplet 7 dropping from the nozzle 6. images in chronological order.

The dripping detection section 152b sequentially detects "liquid runout" in which the droplet 7 separates from the nozzle 6 and begins to drip, based on the images generated in chronological order by the image generation section 152a. Specifically, the dripping detection unit 152b creates a rectangular area having a predetermined size at a position a predetermined distance below the position where the nozzle tip 6a is captured in the images sequentially generated by the image generation unit 152a. and monitor the inside of the rectangular area. Then, after detecting an image showing the droplet 7 hanging down on the nozzle tip 6a, the dripping detection unit 152b detects an image showing the droplet 7 separating from the nozzle 6 and starting to fall. When an image is detected, it is determined that "liquid run out" has occurred. The dripping detection unit 152b outputs the timing at which this liquid-out image is detected as the liquid-out timing. Further, the droplet detection unit 152b may count the number of times a liquid out image is detected within a predetermined time, and output this number of times as the number of droplets to be dropped.

The volume calculation unit 152c calculates the volume of the droplet 7 dropped from the nozzle 6 based on the images generated in chronological order by the image generation unit 152a. The method for calculating the volume of a droplet based on an image is not particularly limited. As an example, an image of a droplet falling away from the nozzle 6 is binarized to extract the region of the droplet, and this region is regarded as a projected image of a rotating body, and the rotating body is sliced into a circle. The volume of the rotating body (droplet) may be calculated by calculating the area of these circles and integrating the areas of these circles. In addition, as another example, the volume of the droplet immediately before falling into the nozzle 6 and the volume of the liquid remaining in the nozzle 6 after the droplet has fallen from the nozzle 6 are calculated, respectively, and the volume of the droplet immediately before falling is calculated. The net volume of the droplet may be calculated by subtracting the volume of the remaining liquid from the volume of the droplet (reference: JP 2018-148962A). In either method, the volume of the droplet calculated on the scale of the number of pixels based on the image is converted to the scale in real space (milliliter or microliter).

The dropping cycle calculation unit 153 calculates a measured value of the time interval (dropping cycle) at which the droplet 7 is dropped from the nozzle 6 based on the dropout timing or the number of drops sequentially detected by the dropping detection unit 152b. The measured value of the dropping period may be the time interval between the dropping times of individual droplets, or may be the average value of the time intervals between the dropping times of a plurality of droplets.

Here, let t0, t1, t2, . The dropping period calculation unit 153 may obtain the measured value of the dropping period by calculating the difference in the time interval at which the droplets are dropped for each drop. Specifically, it is as follows.
T(t1)=t1-t0
T(t2)=t2-t1
T(t3)=t3-t2

Alternatively, the dropping cycle calculation unit 153 may use the average value of the time intervals at which a plurality of droplets are dropped as the measured value of the dropping cycle. Specifically, it is as follows.
T(t1), T(t2),..., T(t10) = (t10-t0)/10
T(t11), T(t12),..., T(t20)=(t20-t10)/10
T(t21), T(t22),..., T(t30)=(t30-t20)/10

Furthermore, the dropping period calculation unit 153 may use the times at which droplets are dropped overlappingly when calculating the average value of the time intervals. That is, as follows.
T(t10)=(t10-t0)/10,
T(t15)=(t15-t5)/10,
T(t20)=(t20-t10)/10,...

Alternatively, the dropping cycle calculation unit 153 may calculate the measured value of the dropping cycle based on the number of droplets dropped within a predetermined period (for example, 1 minute, 10 minutes, etc.). Specifically, it is as follows.
(Drop cycle) = (predetermined time) / (number of drops)

The range of droplets when calculating the average value in measuring the dropping period is not particularly limited. Preferably, a range of several drops to several tens of drops can be used, and more preferably a range of about 10 to 50 drops can be used.

The target period calculation unit 154 calculates the period based on the volume (V (mL)) of the droplet 7 calculated by the volume calculation unit 152c and the target flow rate (F0 (mL/h)) stored in the set value storage unit 143. , the target dropping period (T (sec)) is calculated using the following equation (1).
T (sec) = 3600/(F0/V)...(1)

The dropping cycle adjustment unit 155 controls the control valve or pump unit provided in the flow rate adjusting unit 8 so that the measured value of the dropping cycle of droplets dropped from the nozzle 6 approaches the target dropping cycle.

The light source control unit 156 controls the light control unit CL included in the light source 11 to turn on/off the light emitting elements L and adjust the amount of light for each element or for each element group.

Note that the hardware configuration of the calculation unit 150 is not limited to that described above, and each functional configuration of the calculation unit 150 may be realized using a circuit such as an FPGA (Field Programmable Gate Array).

(Summary of flow rate control method)
The flow rate control method according to the present embodiment measures the volume of a droplet dripping from the nozzle 6 based on an image of the droplet, and determines an appropriate flow rate based on the measured volume of the droplet and a target flow rate. It calculates the dropping period (target period) and controls the operation of the flow rate adjustment unit 8 so that the dropping period approaches the target period.

Here, in a general drip system, it is assumed that the volume of droplets dropped from a nozzle is constant, and the flow rate is controlled by adjusting only the drop period. Specifically, there are two types of drip nozzles: one for 20 drops/mL and one for 60 drops/mL. The volume is fixed at 16.67 μL, and the target dropping period is calculated using these fixed values.

However, when the inventors conducted an experiment to measure the volume of droplets dripping from a nozzle based on images, it was found that even when the same type of liquid is dripped from nozzles with the same diameter, the droplet frequency varies depending on the droplet frequency. It was discovered that the volume of the droplet changes. FIGS. 5 to 8 are graphs showing the experimental results, and show changes in the volume of droplets depending on the dropping period. Of these, FIG. 5 shows changes in the volume of physiological saline. FIG. 6 shows changes in the volume of sugar solution. FIG. 7 shows the change in volume of ultrapure water.

In the case of physiological saline, as shown in FIG. 5(a), the volume of the droplets dropped from the 20 drops/mL nozzle is larger than the expected volume (50.0 μL/drop), and in particular, The error is large when the dropping cycle is short. Furthermore, as shown in FIG. 5B, the volume of droplets dropped from the 60 drop/mL nozzle is smaller than the expected volume (16.67 μL/drop) and varies depending on the drop period.

On the other hand, in the case of sugar solution, as shown in FIG. 6(a), the volume of droplets dropped from a 20 drop/mL nozzle is smaller than the expected volume, and the longer the drop cycle is, the more the error occurs. becomes noticeable. Further, as shown in FIG. 6B, the volume of the droplet dropped from the 60 drop/mL nozzle is smaller than the expected volume, and the error increases as the drop period becomes longer.

In the case of ultrapure water, as shown in FIG. 7(a), the volume of droplets dropped from a 20 drop/mL nozzle becomes smaller than the expected volume as the drop period moves away from around 1.0 seconds. The error becomes larger. As shown in FIG. 7(b), the same holds true for the volume of droplets dropped from the 60 drop/mL nozzle.

In this way, in reality, the droplet volume and the dropping period are correlated with each other, so the general method that only adjusts the dropping period assumes that the volume of the droplet dropping from the nozzle is constant. With the flow rate control method, it is difficult to control the flow rate with high precision. On the other hand, it is also possible to precisely control the flow rate by continuously measuring the volume of droplets using image processing. However, in this case, the computational processing load involved in controlling the flow rate increases. As a result, a high-spec information processing unit is required, making it difficult to downsize and save power of the flow rate control system and infusion pump.

Furthermore, as time passes after starting the drip, the liquid that has bounced back inside the drip tube 4 may adhere to the inner wall, or the inner wall of the drip tube 4 may become cloudy due to steam. Therefore, as time passes, it becomes increasingly difficult to accurately detect the region of the droplet in the image, and the error in measuring the volume of the droplet based on the image may increase. In other words, if the flow rate is continuously controlled based on the volume of the droplet measured by image processing, there is a risk that the error in the flow rate will increase instead.

Therefore, the inventors of the present invention have proposed a flow rate control method according to the present embodiment, which is capable of controlling the flow rate of an infusion with high precision while suppressing the computational processing load while taking into account the variation in droplet volume due to the droplet cycle. I came up with this idea. The flow rate control method according to this embodiment will be described in detail below.

(Details of flow rate control method)
FIG. 8 is a flowchart showing the operation of the flow control system 10. 9 and 10 are images for explaining the control of the light source in the flow rate control method according to the present embodiment. Of these, FIG. 9 shows the state in which the vicinity of the tip of the nozzle for 20 drops/mL is illuminated, and FIG. 10 shows the state in which the vicinity of the tip of the nozzle for 60 drops/mL is illuminated. .

Prior to starting the drip, the user adjusts the positions of the light source 11 and camera 12 with respect to the drip tube 4 (see FIG. 1). At this time, the user operates the information processing unit 100 to display the image captured by the camera 12 on the display unit 120, and while viewing the image, the user can check whether the nozzle tip 6a and a predetermined range below the nozzle tip 6a are visible to the camera. The positional relationship between the light source 11, the drip tube 4, and the camera 12 can be adjusted so that they are within the field of view.

First, as an initial setting, the information processing section 100 sets the flow rate (target flow rate F0) of the droplet 7 to be dropped from the nozzle 6 based on a signal input from the operation input section 110 (step S101). This target flow rate is stored in the storage unit 140.

Subsequently, the information processing unit 100 causes the camera 12 to start capturing images (step S102). From this, the image data generated by the camera 12 is sequentially input to the information processing section 100.

At this time, the light source control section 156 of the information processing section 100 may turn on all the light emitting elements L of the light source 11. As a result, at least a region of the field of view of the camera 12 necessary for detecting the lack of liquid droplet 7 dropping from the nozzle 6 and calculating the volume of the droplet 7 dropping from the nozzle 6 is illuminated. The area required to calculate the volume of the droplet 7 differs depending on the droplet volume calculation algorithm. For example, when calculating the volume by capturing an image of a droplet falling away from the nozzle 6, the tip 6a of the nozzle 6 and a relatively long area below the nozzle 6 (for example, the droplet 7 (approximately 4 to 5 times the size) will be illuminated. On the other hand, when calculating the volume by capturing the image of the droplet just before falling, the area below the nozzle 6 may be shorter (for example, the size of the droplet 7 1 to 2 times (see FIG. 9(a) and FIG. 10(a)).

Thereafter, the information processing unit 100 transmits a control signal to the flow rate adjustment unit 8 to start dripping in response to the operation on the operation input unit 110, and starts measuring the dripping cycle (step S103). That is, based on the image data sequentially inputted from the camera 12, the image processing unit 152 (droplet detection unit 152b) starts detecting the timing when the droplets dripping from the nozzle 6 run out, and detects the timing when the droplets drop from the nozzle 6 runs out. Then, the dropping cycle calculation unit 153 starts calculating the dropping cycle. Of course, the dropping cycle may be calculated based on the number of times the liquid runs out (the number of drops) in a predetermined period.

Here, at the time of starting the infusion, the control valve 9 is gradually opened from the closed state, but at this time, the target dripping cycle is provisionally set based on the target flow rate, and the dripping cycle is The flow rate adjustment unit 8 is controlled to open the control valve 9 so that the measured value approaches the provisional target dropping cycle. For example, when using a nozzle for 20 drops/mL, the theoretical volume per drop is 0.05 mL, so if the target flow rate is 300 mL/h, the tentative target drop cycle is 0.6 seconds. becomes.

However, at the start of dripping, in order to prevent overflow, a provisional target dripping period (third target dripping period) may be set based on a flow rate smaller than the original target flow rate. For example, the flow rate that does not overflow may be set to 1/2 (or 1/3, 1/4, etc.) of the original target flow rate. Alternatively, a value obtained by subtracting a predetermined value from the original target flow rate (for example, minus 100 mL/h) may be set as the flow rate that does not overflow. For example, if you set the original target flow rate of 300 mL/h to 150 mL/h, which is 1/2 as a flow rate that will not overflow, and if you use a nozzle for 20 drops/mL, the tentative target drip cycle is It will be 1.2 seconds.

After the drip is started and the control valve 9 is opened so that the measured value of the drip cycle is approximately in the vicinity of the provisional target drip cycle, the volume calculation unit 152c, based on the image data input from the camera 12, The volume Va of the droplet dropped from the nozzle 6 (volume of the first droplet) is calculated (step S104). The timing at which the volume Va is first calculated depends on the period of flow rate control based on the provisional target dripping cycle, but may generally be within a period of several seconds to tens of seconds or tens of seconds from the start of dripping. Further, the value output as the volume Va may be the volume calculated for one drop, or may be the average value of the volumes calculated for multiple drops. For example, the volume Va may be the average value of the volumes of several to ten or more drops that are continuously dropped.

Subsequently, the target period calculating unit 154 calculates a target dropping period Ta (first target dropping period: Ta=Va/F0) based on the volume Va of the droplet and the target flow rate F0 of the drip (step S105 ).

The dropping cycle adjustment unit 155 determines whether the dropping cycle (measured value) calculated by the dropping cycle calculating unit 153 is stable (step S106). Here, the expression that the dropping period is stable means that the dropping period remains within a certain error range for several tens of seconds to several minutes. As for the range of error, for example, an average error of about ±10% for several drops to several tens of drops (about 10 to 50 drops) is allowed.

If the dropping cycle is not stable (Step S106: No), the dropping cycle adjustment unit 155 controls the flow rate adjusting unit 8 so that the measured value of the dropping cycle approaches the target dropping cycle Ta (Step S107, (first feedback control).

After the dropping cycle is stabilized (step S106: Yes), the volume calculating unit 152c calculates the volume Vb of the droplet 7 dripping from the nozzle 6 (the volume Vb of the second droplet) based on the image data input from the camera 12. volume) is calculated (step S108). The value output as the volume Vb may also be the volume calculated for one drop, or the average value of the volumes calculated for multiple drops.

Subsequently, the target period calculating unit 154 calculates a target dropping period Tb (second target dropping period: Tb=Vb/F0) based on the volume Vb of the droplet and the target flow rate F0 of the drip (step S109 ).

The dropping cycle adjustment unit 155 determines whether the dropping cycle (measured value) calculated by the dropping cycle calculating unit 153 matches the target dropping cycle Tb (step S110). If the measured value of the dropping cycle matches the target dropping cycle Tb (step S110: Yes), the process directly moves to step S112. On the other hand, if the measured value of the dropping cycle deviates from the target dropping cycle Tb (step S110: No), the dropping cycle adjustment unit 155 finely adjusts the dropping cycle so that the measured value approaches the target dropping cycle Tb ( Step S111, second feedback control). After that, the process moves to step S112.

Here, during execution of the second feedback control, the image data input from the camera 12 is used exclusively for detecting the timing of liquid exhaustion for measuring the drip cycle. Therefore, the light source control unit 156 may turn off some of the light emitting elements L within the field of view of the camera 12, within a range where the area necessary for detecting the timing of liquid exhaustion is illuminated. Specifically, it is sufficient that the upper part of the droplet 7 hanging down the nozzle 6 is illuminated (see (b) in FIG. 9 and (b) in FIG. 10). For example, in the light source 11 shown in FIGS. 2 and 3, when the first feedback control shifts to the second feedback control, the light emitting elements L in the rows 11a, 11b, 11e, and 11f are turned off, and the light emitting elements L in the rows 11c, Such an illumination state can be realized by causing only the light emitting element L of 11d to emit light.

Further, when shifting from the first feedback control to the second feedback control, some of the light emitting elements L of the light source 11 may be turned off, and then the light amount of the light emitting elements L that are emitting light may be increased. Specifically, the total amount of light from the light emitting elements L that emit light during execution of the second feedback control becomes approximately the same as the total amount of light from the light emitting elements L that emit light during the execution of the first feedback control. In this way, the dimming value of each light emitting element L that continues to emit light during execution of the second feedback control is increased (see (c) in FIG. 9 and (c) in FIG. 10). For example, in the light source 11 shown in FIGS. 2 and 3, if the minimum dimming value of each light emitting element L is 0 and the maximum value is 200, each light emitting element L is By setting the dimming value to 27 and setting the dimming value of each light emitting element L to 55 when only the light emitting elements L in rows 11c and 11d emit light, the total dimming value can be made approximately the same. . By controlling the dimming value in this way, even during execution of the second feedback control, it is possible to obtain an image with approximately the same brightness as during execution of the first feedback control.

The information processing unit 100 repeats the processes of steps S110 to S112 until the specified amount of infusion is completed (step S112: No, step S110). When the prescribed amount of infusion is completed (step S112: Yes), the information processing unit 100 causes the camera 12 to end imaging (step S113). After that, the operation of the flow control system 10 ends.

(First example)
An experiment was conducted in which the drip was performed using the drip system 1 shown in FIG. 1 and the flow rate was controlled. The experimental conditions are as follows.
Chamber: Room temperature: 24°C, humidity: 0% RH in a constant temperature bath Infusion set: Commercially available product for 20 drops/1mL Infusion: Distilled water Infusion density: 0.997316g/mL
Target flow rate: 300mL/h
Infusion period: 120 minutes

FIG. 11 is a graph showing a startup curve in the first example. Here, the startup curve indicates the flow rate characteristics from immediately after the start of infusion until the flow rate becomes stable. In FIG. 11, the horizontal axis shows the elapsed time (minutes) from the start of infusion, and the vertical axis shows the actual measured value of the flow rate (mL/h).

In the experiment, dripping was first started by gradually opening the control valve provided in the flow rate adjustment unit 8. Thereafter, the volume Va of the droplet was measured based on the image obtained by taking an image with a camera. Then, a first target dropping period Ta (=Va/F0) was calculated based on this volume Va.

Thereafter, the control valve was adjusted little by little so that the dropping cycle approached the target dropping cycle Ta. In addition, in the actual adjustment, the number of drops per minute or the number of drops per 10 minutes is counted, and the control valve is adjusted so that this counted number approaches the target number of drops per time calculated from the target dropping period Ta. This was done by opening and closing. As a result of this adjustment, as shown in FIG. 11, the dripping cycle began to become stable from about 5 minutes after the start of dripping. Such control was continued for about 10 minutes from the start of the infusion (see period t1).

Approximately 10 minutes after the start of the infusion, the volume Vb of the droplet is measured based on the image captured by the camera, and the second target drip cycle Tb (=Vb/F0) is determined based on this volume Vb. was calculated. Then, the control valve was controlled so that the dropping cycle approached the target dropping cycle Tb. The actual adjustment was performed by opening and closing the control valve so that the number of drops per minute or the number of drops per 10 minutes approached the target number of counts per time calculated from the target dropping cycle Tb ( (See period t2). Such control was performed for about 120 minutes in total.

The actual value of the flow rate is determined by measuring the weight of multiple droplets dropped during a predetermined period using an electronic balance (manufactured by Shimadzu Corporation, model: AUW220D), and calculating the volume value by dividing this weight by the infusion density. This volume value was calculated by converting it into a value per unit time.

In FIG. 11, it can be seen that the measured value of the flow rate converges around the target flow rate (300 mL/h) as time passes. In this experiment, the average measured value of the flow rate was 294.38 mL/h from 0 minutes to 60 minutes after the start of dripping, and 296.06 mL/h from 60 minutes to 120 minutes, and the more time passes, the more accurate the flow rate control becomes. It can be seen that the results are improved.

12 and 13 are graphs showing trumpet curves in flow rate control according to the first embodiment. Of these, FIG. 12 is a graph regarding the entire measurement period (0 to 120 minutes), and FIG. 13 is a graph regarding the latter half hour (60 to 120 minutes). Here, the trumpet curve is a plot of the maximum and minimum values of the flow rate error for each observation window set for the measurement period, and indicates the fluctuation characteristics of the flow rate error in a stable state. Specifically, the narrower the interval between the upper curve and the lower curve, the smaller the fluctuation in the flow rate error. It can also be seen from FIGS. 12 and 13 that in the second half when the second feedback control is executed, the error fluctuation is smaller and the flow rate can be controlled with higher accuracy.

(Second example)
An experiment was conducted to control the flow rate by changing the infusion set and target flow rate for the first example. The experimental conditions and experimental procedures were the same as in the first example, except that a commercial product for 60 drops/1 mL was used as the infusion set, and the target flow rate was set to 75 mL/h.

FIG. 14 is a graph showing a startup curve in the second example. Also in FIG. 14, it can be seen that the actual measured value of the flow rate converges around the target flow rate (75 mL/h) as time passes. In this experiment, the average measured value of the flow rate was 75.96 mL/h from 0 minutes to 60 minutes after the start of dripping, and 75.16 mL/h from 60 minutes to 120 minutes, and the accuracy of flow rate control increases as time passes. It can be seen that the results are improved.

15 and 16 are graphs showing trumpet curves in flow rate control according to the second embodiment. Of these, FIG. 15 is a graph regarding the entire measurement period (0 to 120 minutes), and FIG. 16 is a graph regarding the latter half hour (60 to 120 minutes). Also in FIGS. 15 and 16, it is shown that the error fluctuation is smaller in the second half when the second feedback control is executed, and the flow rate can be controlled with higher accuracy.

As explained above, according to the present embodiment, the target dropping cycle is calculated based on the set value of the flow rate and the volume of the droplet measured based on the image of the droplet, and the target dropping cycle is Adjust the dripping cycle so that it approaches . Therefore, it is possible to perform highly accurate flow rate control that also takes into account variations in the volume of droplets depending on the droplet cycle.

In addition, in this embodiment, only when calculating the first target dropping cycle used in the first feedback control and the second target dropping cycle used in the second feedback control, the liquid droplet based on the image is used. Since the volume of the droplet is measured, the load on calculation processing can be significantly reduced compared to the case where the volume of the droplet is always measured.

Further, according to the present embodiment, after the second feedback control is started, the volume measurement of the droplet based on the image is not performed, and the control is performed based on the already calculated second target dropping cycle. , it is possible to suppress maladjustment of flow rate due to volume measurement error that increases over time.

Further, according to the present embodiment, when transitioning to the second feedback control, a part of the light source 11 emits light within a range in which the area necessary for detecting the timing of liquid exhaustion in the field of view of the camera 12 is illuminated. Since the element L is turned off, the power of the light source 11, which consumes relatively large power in the flow rate control system 10, can be suppressed. Therefore, when the light source 11 is driven by a battery, the driving time can be extended.

Further, according to the present embodiment, when transitioning to the second feedback control, the total light amount of the light emitting elements L lit in the light source 11 is equal to the total light amount of the light emitting elements L lit during the first feedback control. Since the dimming value of each light emitting element L is adjusted so as to be approximately equal to the total light amount of can be obtained.

Here, the brightness of the image can also be adjusted by adjusting the exposure time of the camera 12, the aperture value of the camera lens, etc. However, since it takes time to change the values on the camera 12 side, it is not practical to change these values after the infusion has started. In this respect, since the light intensity of the light source 11 can be easily and instantly changed by simply adjusting the dimming value of each light emitting element, it is possible to seamlessly transition from the first feedback control to the second feedback control. becomes possible.

(Modification 1)
In the first feedback control (control until the dropping cycle is stabilized) in the above embodiment, the volume Va of the droplet is calculated by image processing only once when starting the control, and based on this volume Va. Then, the first target dropping period Ta was calculated. However, during execution of the first feedback control, the volume Va of the droplet may be further calculated by image processing, and the target dropping period Ta may be updated based on this volume Va. That is, instead of moving from step S107 to step S106 shown in FIG. 8, the process may move from step S107 to step S105 periodically or when a predetermined condition is satisfied. Specifically, the target dropping cycle Ta is updated at intervals of several minutes (for example, 3 to 5 minutes), or the target dropping cycle is updated when the error in the measured value of the dropping cycle falls within a predetermined range (for example, ±30%). An example is updating the period Ta.

In addition, in the second feedback control (control for bringing the dropping cycle closer to the second target dropping cycle Tb), as in the above embodiment, when transitioning to the second feedback control, droplets calculated by image processing are A second target dropping period Tb is calculated based on the volume Vb of the droplet, and thereafter the volume of the droplet is basically not calculated by image processing.

(Modification 2)
In the above embodiment, the dropping of the droplet is detected by image processing on the image showing the droplet, the timing of the liquid running out is detected or the number of drops is counted, and the dropping cycle is calculated based on the timing of the liquid running out or the number of drops. It was decided to. However, during execution of the first feedback control or the second feedback control, the means for detecting the timing of liquid shortage or counting the number of drops (drop detection means) is not limited to this, and various known means may be used. I can do it.

As an example of the drop detection means, a light source that emits a light beam such as infrared light and a photodetector (PD) that can detect the light beam emitted from the light source may be used. In this case, a light source and a photodetector are installed so as to face each other across a line vertically below the nozzle, and the light beam emitted from the light source is detected by the photodetector. When a droplet falls from a nozzle, the detection signal output from the photodetector changes at the moment the droplet blocks light, so the number of drops can be determined by counting the number of times the detection signal changes.

As another example of the drop detection means, a combination of a light source such as an LED and a line sensor including a CCD or CMOS may be used. In this case, a line sensor is placed near the lower end of the nozzle, and the line sensor captures an image of a droplet hanging from the nozzle, gradually growing, and finally falling. Then, the width of the image of the droplet reflected on the line sensor is detected, and the moment when this width gradually decreases to zero can be determined as a liquid shortage.

The present invention described above is not limited to the embodiments and modifications described above, and various inventions can be formed by appropriately combining the plurality of components disclosed in the embodiments and modifications described above. can. For example, it may be formed by excluding some components from all the components shown in the above embodiments and modifications, or it may be formed by appropriately combining the components shown in the above embodiments and modifications. good.

1... Infusion system, 2... Infusion bag, 2a... Drainage port, 3... Intermediate tube, 4... Infusion tube, 4a... Upper lid, 5... Infusion tube, 6... Nozzle, 6a... Nozzle tip, 7... Droplet, 8...Flow rate adjustment unit, 9...Control valve, 10...Flow rate control system, 11...Light source, 12...Camera, 12a...Image sensor, 20...Infusion pump, 100...Information processing unit, 110...Operation input unit, 120...Display 130...External interface, 140...Storage unit, 141...Program storage unit, 142...Image data storage unit, 143...Setting value storage unit, 150...Calculation unit, 151...Imaging control unit, 152...Image processing unit, 152a ...Image generation section, 152b...Dripping detection section, 152c...Volume calculation section, 153...Dripping cycle calculation section, 154...Target cycle calculation section, 155...Dripping cycle adjustment section, 156...Light source control section

Claims (11)

A flow rate control system for controlling the flow rate of droplets in a drip system equipped with a flow rate adjustment unit that changes the flow rate of droplets dripping from a nozzle, comprising:
an imaging device configured to image droplets dripping from the nozzle and output image data;
a volume calculation unit configured to calculate the volume of a droplet falling from the nozzle based on image data output from the imaging device;
Drop detection means configured to detect the timing at which a droplet begins to fall away from the nozzle or the number of times a droplet falls away from the nozzle;
a dropping cycle calculation unit configured to calculate a dropping cycle in which droplets are dropped from the nozzle based on the timing or the number of times;
a target period calculating section configured to calculate a target dropping period based on a preset target flow rate and the volume of the droplet calculated by the volume calculating section;
a drip cycle adjustment unit configured to control the flow rate adjustment unit so that the drip cycle calculated by the drip cycle calculation unit approaches the target drip cycle;
Equipped with
The target period calculation unit is configured to calculate a first target dropping period based on the volume of the first droplet calculated for the droplet dropped from the nozzle after the start of infusion,
The dropping cycle adjustment unit is configured to perform first feedback control so that the dropping cycle calculated by the dropping cycle calculation unit approaches the first target dropping cycle,
The target period calculation unit further calculates a second target dropping period based on the volume of the second droplet calculated for the droplet dropped from the nozzle after the dropping period is stabilized by the first feedback control. is configured to calculate
The dripping cycle adjustment unit is further configured to perform second feedback control so that the dripping cycle calculated by the dripping cycle calculation unit approaches the second target dropping cycle. The target cycle calculating unit determines that the dropping cycle is stabilized when the dropping cycle calculated during the period of the first feedback control falls within an error range of 10%, and after making the determination, The flow rate control system according to claim 1, configured to calculate the second target dropping period based on the volume of the second droplet calculated for the droplet dropped from the nozzle. 3. The flow control system according to claim 1, wherein the volume calculation unit is configured to stop calculating the volume of the droplet after the second feedback control is started. The dropping cycle calculation unit is further configured to update the first target dropping cycle based on the volume of the droplet calculated for the droplet dropped from the nozzle during execution of the first feedback control. is,
The flow rate control according to claim 1 or 2, wherein the drip cycle adjustment unit is configured to perform first feedback control so as to approach the first target drip cycle updated by the drip cycle calculation unit. system. The dripping cycle adjustment unit is configured to adjust the dripping cycle calculated by the dripping cycle calculation unit to a third rate calculated based on a flow rate smaller than the target flow rate and a theoretical droplet volume at the start of infusion. The flow rate control system according to claim 1 or 2, wherein the flow rate adjustment unit is controlled so as to approach a target dripping period. The drip detection means detects the timing or the number of times based on image data output from the imaging device,
a light source having a plurality of light emitting elements and configured to illuminate a field of view of the imaging device;
a light source control unit configured to control on/off of the plurality of light emitting elements;
Furthermore,
The light source control section includes:
The plurality of light emitting lights are arranged so that at least an area of the field of view of the imaging device necessary for detecting the timing and calculating the volume of the droplet is illuminated from the start of the infusion until the end of the first feedback control. Controls the on/off of the element,
During execution of the second feedback control, some of the light emitting elements of the plurality of light emitting elements are turned off within a range in which a region necessary for detecting the timing in the field of view of the imaging device is illuminated;
The flow control system according to claim 1 or 2. The light source control unit further controls the total amount of light of the light emitting elements emitted during execution of the second feedback control to be approximately the same as the total amount of light of the light emitting elements emitted during execution of the first feedback control. 7. The flow rate control system according to claim 6, wherein the amount of light emitted by each light emitting element is increased during execution of the second feedback control. a tube holding part configured to hold an infusion tube connected to the drip barrel;
a pump section configured to pump the liquid in the infusion tube by pressing the infusion tube;
an interface configured to acquire image data output from an imaging device that images droplets dripping into the drip tube from a nozzle attached to the drip tube;
an operation input section that accepts input of a target flow rate;
a volume calculation unit configured to calculate the volume of a droplet falling from the nozzle based on image data output from the imaging device;
Drop detection means configured to detect the timing at which a droplet begins to fall away from the nozzle or the number of times a droplet falls away from the nozzle;
a dropping cycle calculation unit configured to calculate a dropping cycle in which droplets are dropped from the nozzle based on the timing or the number of times;
a target cycle calculation unit configured to calculate a target dropping cycle based on the target flow rate accepted by the operation input unit and the volume of the droplet calculated by the volume calculation unit;
a drip cycle adjustment unit configured to control the pump unit so that the drip cycle calculated by the drip cycle calculation unit approaches the target drip cycle;
Equipped with
The target period calculation unit is configured to calculate a first target dropping period based on the volume of the first droplet calculated for the droplet dropped from the nozzle after the start of infusion,
The dropping cycle adjustment unit is configured to perform first feedback control so that the dropping cycle calculated by the dropping cycle calculation unit approaches the first target dropping cycle,
The target period calculation unit further calculates a second target dropping period based on the volume of the second droplet calculated for the droplet dropped from the nozzle after the dropping period is stabilized by the first feedback control. is configured to calculate
The infusion pump is further configured to perform a second feedback control such that the drip cycle calculated by the drip cycle calculation unit approaches the second target drip cycle. The infusion pump according to claim 8;
the drip barrel to which the nozzle is attached;
an infusion tube connected to the drip tube;
A drip system equipped with. A flow rate control method for controlling the flow rate of droplets in an intravenous drip system equipped with a flow rate adjustment unit that changes the flow rate of droplets dripping from a nozzle, the method comprising:
an imaging step of imaging a droplet dripping from the nozzle and outputting image data;
a volume calculation step of calculating the volume of the droplet falling from the nozzle based on the image data output in the imaging step;
a dripping detection step of detecting the timing at which a droplet starts falling away from the nozzle or the number of times the droplet falls away from the nozzle;
a dropping cycle calculation step of calculating a dropping cycle in which droplets are dropped from the nozzle based on the timing or the number of times;
a first target cycle calculation step of calculating a first target drip cycle based on a preset target flow rate and a volume of the first droplet calculated for the droplet dropped from the nozzle after the start of infusion; and,
a first drip cycle adjustment step of performing feedback control on the flow rate adjustment unit so that the drip cycle calculated in the drip cycle calculation step approaches the first target drip cycle;
A second target dropping volume is calculated based on a preset target flow rate and a second droplet volume calculated for the droplets dropped from the nozzle after the dropping cycle is stabilized by the first flow rate adjustment step. a second target cycle calculation step of calculating the cycle;
a second drip cycle adjustment step of performing feedback control on the flow rate adjustment unit so that the drip cycle calculated in the drip cycle calculation step approaches the second target drip cycle;
Flow rate control method including. A program that is executed by a computer in an intravenous drip system equipped with a flow rate adjustment unit that changes the flow rate of droplets dripping from a nozzle,
an image data acquisition step of acquiring the image data from an imaging device that images the droplets dripping from the nozzle and outputs the image data;
a volume calculation step of calculating the volume of the droplet falling from the nozzle based on the image data acquired in the image data acquisition step;
a dripping detection step of detecting the timing at which a droplet starts falling away from the nozzle or the number of times the droplet falls away from the nozzle;
a dropping cycle calculation step of calculating a dropping cycle in which droplets are dropped from the nozzle based on the timing or the number of times;
a first target cycle calculation step of calculating a first target drip cycle based on a preset target flow rate and a volume of the first droplet calculated for the droplet dropped from the nozzle after the start of infusion; and,
a first drip cycle adjustment step of performing feedback control on the flow rate adjustment unit so that the drip cycle calculated in the drip cycle calculation step approaches the first target drip cycle;
A second target dropping volume is calculated based on a preset target flow rate and a second droplet volume calculated for the droplets dropped from the nozzle after the dropping cycle is stabilized by the first flow rate adjustment step. a second target cycle calculation step of calculating the cycle;
a second drip cycle adjustment step of performing feedback control on the flow rate adjustment unit so that the drip cycle calculated in the drip cycle calculation step approaches the second target drip cycle;
A program to run.

Images