KR102606089B1 - Control method of medical robot bed for bedsore prevention using body pressure sensor - Google Patents

Abstract

In the method of controlling a medical robot bed for bedsore prevention using a body pressure sensor of the present invention, a plurality of raising and lowering link modules whose raising and lowering are independently controlled by parallelogram links are arranged adjacent and parallel on the upper surface of the bed support, and each of the lifting and lowering link modules is arranged in parallel. In the control method of a bedsore prevention medical robot bed in which the lowering link module is controlled by a servo motor, the body pressure of each part of the human body applied to each lowering link module is sensed through a body pressure sensor provided in each lowering link module. Information is constantly collected and transmitted to the operation control unit, and the operation control unit reads the body pressure sensing information collected from the body pressure sensor of each of the plurality of lifting link modules and collects the body pressure sensing information transmitted from the body pressure sensor of the specific lifting link module. When a pressure ulcer approaches 32 mmHg, which is the critical pressure for pressure ulcers at which pressure ulcers can occur, all lowering link modules, including the specific lowering link module, immediately before reaching the critical pressure for pressure ulcers. From this parallel initial first vertical position (h1), only specific lifting and lowering link modules that are close to the bedsore critical pressure are lowered to a second vertical position (h2) that is relatively lower than the first vertical position (h1). The operation is stopped for a set constant residence time, and after the certain residence time has elapsed, the specific lifting and lowering link module stopped at the second vertical position (h1) is raised again to the original first vertical position (h1). The lifting and lowering motion and vertical position of each lifting and lowering link module are independently controlled according to body pressure sensing information.

Description

Control method of medical robot bed for bedsore prevention using body pressure sensor {Control method of medical robot bed for bedsore prevention using body pressure sensor}

The present invention relates to a method of controlling a medical robot bed for bedsore prevention using a body pressure sensor. More specifically, it relates to a method of controlling a medical robot bed for bedsore prevention using a body pressure sensor. More specifically, it relates to a method of controlling a medical robot bed for bedsore prevention using a multi-parallelogram link structure in which the raising and lowering is independently controlled in the form of a raising and lowering link module along the bed surface of the bed. A medical robot for preventing bedsores using a body pressure sensor that is highly effective in preventing bedsores and skin diseases by arranging a plurality of lowering link modules adjacent to each other in parallel and controlling the raising and lowering movement of the lowering link modules appropriately according to the patient's nursing situation. It's about how to control the bed.

In general, medical beds used in hospitals are structured so that the backrest or footrest can be rotated and folded at a certain angle for patients with limited mobility, and the guardian can turn the operating handle to adjust the angle of the backrest, either manually or with a drive motor. Alternatively, it is divided into an electric type that uses a hydraulic cylinder to adjust the angle of the backrest with electric power.

Manual medical beds have the advantage of being inexpensive in that they do not require a separate electric device, but there is a problem that it is difficult for patients with mobility issues to use them themselves because it requires a lot of force to adjust the angle of the backrest.

For this reason, in recent years, electric beds that allow patients to adjust the angle of the backrest themselves are preferred, even though the purchase cost is somewhat expensive.

One example of such a conventional medical electric bed is disclosed in Domestic Patent No. 10-0621349 (hereinafter referred to as ‘prior document’).

Referring to Figures 1 and 2 of the prior literature, the conventional medical electric bed largely includes a bed frame 10, a backrest 21 located on the upper part of the bed frame 10 and rotatably coupled to each other, and An operation module 20 including a leg rest 22, a drive module 30 consisting of a plurality of links rotatably coupled to the operation module 20 and driven by an external force, and the bed frame 10 ) It is located at the bottom and consists of a power module 40 that provides external force for the operation of the drive module 30.

The power module 40 is composed of a first actuator 41 and a second actuator 42. Each first actuator 41 applies power to tilt the backrest 21, and the second actuator 42 Apply power to tilt the leg support portion 22.

In addition, the backrest part 21 is located on the upper surface of the bed frame 10, and one end is rotatably coupled to the fixing part 50 provided in the bed frame 10, and the other end is raised upward by the drive module 30. It is tilted. One end of the thigh portion 22a is rotatably coupled to the other end of the fixing portion 50, one end of the shin portion 22b is rotatably coupled to the other end of the thigh portion 22a, and the footrest portion 22c has one end attached to the thigh ( It is rotatably coupled to the other end of 22a). In this way, the leg rest portion 22 is configured, and the leg rest portion 22 is tilted upward by the drive module 30 coupled to the bed frame 10.

However, in the conventional medical electric bed configured in this way, the mat part is divided into a backrest part, a waist part, a joint part, and a leg support part, and can be driven up and down, so it can be used to sit up a critically ill patient who has difficulty moving the body, or to lift the legs. It is possible to change the posture required for back treatment and nursing activities to a certain extent, but in the case of patients who are unable to move while lying in bed, certain body parts of the patient are pressed against the bed for a long period of time, resulting in poor blood circulation, and air remaining on the skin for a long period of time. There were serious problems with complications such as bedsores and skin diseases due to lack of contact.

Korean Patent No. 10-0621349 (registered on August 31, 2006) Korean Patent No. 10-1709038 (registered on February 15, 2017)

Accordingly, the present invention was developed to solve the above problems, and the lifting and lowering link modules of a multi-parallelogram link structure in which the raising and lowering are independently controlled are adjacent in parallel in the form of a lifting and lowering link module along the bed surface of the bed. Provides a control method for a medical robot bed to prevent bedsores using a body pressure sensor, which is highly effective in preventing bedsores and skin diseases by arranging them in multiple numbers and appropriately controlling the raising and lowering movement of the raising and lowering link modules according to the patient's nursing situation. The purpose is to

According to one embodiment, the method of controlling a medical robot bed for bedsore prevention using a body pressure sensor according to the present invention to achieve the above object includes a plurality of raising and lowering units whose raising and lowering are independently controlled by parallelogram links on the upper surface of the bed support. In the control method of a bedsore prevention medical robot bed in which link modules are arranged adjacent and parallel, and the movement of each of the lifting and lowering link modules is controlled by a servo motor, each lifting and lowering link module is used through a body pressure sensor provided in each lifting and lowering link module. Body pressure sensing information for each part of the human body applied to the lifting link module is constantly collected and transmitted to the operation control unit, and the operation control unit reads the body pressure sensing information collected from the body pressure sensors of each lifting link module and performs a specific When the body pressure sensing information transmitted from the body pressure sensor of the lifting link module approaches 32mmHg, which is the critical pressure for bedsores at which bedsores can occur, a specific lifting link module that is close to the critical pressure for bedsores immediately before reaching the critical pressure for bedsores. In an initial first vertical position (h1) in which all lifting link modules, including a specific lifting link module, are parallel, only the specific lifting link modules that are close to the pressure ulcer threshold pressure are positioned relative to the first vertical position (h1). After lowering to the lower second vertical position (h2), the operation is stopped for a preset certain residence time, and after the certain residence time has elapsed, the specific lifting and lowering link module stopped at the second vertical position (h1) is stopped. By raising it back to the original first vertical position (h1), the raising and lowering operation and vertical position of each lifting and lowering link module are independently controlled according to body pressure sensing information.

Additionally, according to one embodiment, the operation control unit,

The maximum body pressure in each raising and lowering link module is calculated by Equation 1 below,

(Formula 1)

(Here, Pmi is the maximum pressure of the lowering link module i, Pij is the body pressure measured at the jth sensor of the ith lowering link module, and M is the number of body pressure sensors in each lowering link module.)

The error ei is calculated by Equation 2 below,

(Formula 2)

(here, is the target pressure value, is the maximum pressure of key i, is keyboard input.)

The total error (e _RMS ) is calculated by Equation 3 below,

(Formula 3)

(Here, N is the number of ascending and descending link modules.)

The operation control unit independently controls the raising and lowering operation and vertical position of each lifting and lowering link module so that the total error value calculated by the above equation converges to 0.

Also, according to one embodiment, the motion control unit uses a Proportional-Integral (PI) control method or an Integral-Proportional (IP) control method.

Additionally, according to one embodiment, the motion control unit is connected to a servo motor provided in each lifting/lowering link module via CAN (Controller Area Network) communication.

In addition, according to one embodiment, the raising and lowering link module includes at least two parallelogram links connected and arranged side by side on a horizontal line, and the link disposed between each parallelogram link is a multi-parallel link that shares a single link with each other. It has a quadrilateral link structure.

Also, according to one embodiment, the link located in the center among the links shared between the multiple parallelogram links is a phase offset link whose vertical position of the coupling axis is located lower than the other links on the left and right.

Also, according to one embodiment, the phase offset link is a driving link to which a servo motor is coupled.

As described above, the present invention arranges a plurality of lifting and lowering link modules in the form of lifting and lowering link modules, the lifting and lowering of which are independently controlled, along the bed surface, adjacent to each other in parallel, and the lifting and lowering link modules are arranged in parallel and adjacent to each other in accordance with the patient's treatment or nursing situation. Excellent medical care that can prevent serious side effects such as bedsores and skin diseases caused by poor blood circulation or lack of contact with air due to the patient's body being pressed against the bed for a long period of time by appropriately controlling the raising and lowering movement of the lowering link modules. It works.

1 is a perspective view showing the entire medical electric bed of the present invention.
Figure 2 is an enlarged perspective view of the main part of the lifting and lowering link module according to an embodiment of the present invention.
Figure 3 is an exploded perspective view of Figure 2
Figure 4 is an enlarged perspective view of the main part of the lifting and lowering link module according to another embodiment of the present invention.
Figure 5 is an exploded perspective view of Figure 4
Figure 6 is a schematic state diagram for explaining the link operation of the lifting and lowering link module of Figure 4, where (a) is the normal motion state in the case of a single parallelogram link, and (b) is the abnormal state due to the occurrence of the turning point in (a). Movement state, (c) is a normal movement state in which the occurrence of turning points is prevented by applying a double parallelogram link according to the present invention.
Figure 7 is a schematic diagram showing the operation mechanism of the lifting and lowering link module according to the present invention.
Figure 8 is a block diagram showing the control system of the control method of the medical robot bed for bedsore prevention using the body pressure sensor of the present invention.
Figure 9 is a block diagram of an operation control unit of the PI (Proportional-Integral) control method according to an embodiment of the present invention.
Figure 10 is a block diagram of an operation control unit of the IP (Integral-Proportional) control method according to an embodiment of the present invention.
Figure 11 is a graph showing the experimental results of the motion control unit of the PI control method.
Figure 12 is a graph showing the experimental results of the operation control unit of the IP control method

The terms used in this specification are merely used to describe specific embodiments and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, terms such as “include,” “have,” or “equipped with” are intended to designate the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in this specification. It should be understood that this does not preclude the existence or addition of other features, numbers, steps, operations, components, parts, or combinations thereof.

Unless otherwise defined herein, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by a person of ordinary skill in the technical field to which the present invention pertains.

Terms defined in commonly used dictionaries should be interpreted as having meanings consistent with the meanings they have in the context of the related technology, and unless clearly defined in this specification, should not be interpreted in an idealized or overly formal sense. It shouldn't be.

Hereinafter, the configuration and operational relationship of the electric medical bed of the present invention will be examined in detail with reference to the attached drawings.

Figure 1 is an overall perspective view of the electric medical bed of the present invention, Figure 2 is an enlarged main perspective view of the lifting and lowering link module according to one embodiment of the present invention, and Figure 3 is an exploded perspective view of Figure 2.

Hereinafter, the configuration of an electric medical bed according to an embodiment of the present invention will be looked at with reference to FIGS. 1 to 3.

First, the electric medical bed of the present invention is generally provided with a support frame 200 on the top of the bed frame 100 made of steel structure, which can support each part of the body. The support frame 200 is divided into a back support part 210, a waist support part 220, a knee support part 230, and a leg support part 240, and each of the support parts 210, 220, and 230 , 240)'s raising/lowering or rotation angle can be selectively adjusted.

For example, when seating a patient with impaired mobility, the backrest 210 can be lifted upward, while for a patient with impaired mobility, the leg rest 240 can be manipulated to raise or lower the legrest 240 upward. This is possible.

In addition, a headboard 110 and a footboard 120 are provided on the patient's head and leg sides of the bed frame 100, respectively, and the sides of the bed frame 100 have upper and lower bars to prevent the patient from rolling off the bed. A safety bar 130 that is raised and lowered and fixed is further provided.

Meanwhile, as a characteristic component of the present invention, a plurality of raising and lowering link modules are provided on the upper surface of each supporting portion (210, 220, 230, 240) of the supporting frame 200, the raising and lowering of which is independently controlled by parallelogram links. (300) are arranged adjacent to each other and in parallel, and a servo motor (390) is coupled to one of the link coupling axes of each raising/lowering link module (300) to drive the link.

At this time, each lifting link module 300 is separately equipped with a servo motor 390, so that the raising and lowering of each lifting link module 300 can be independently controlled by the servo motor 390. It is understandable that it exists.

Hereinafter, referring to FIGS. 2 and 3, according to one embodiment, each of the raising and lowering link modules 300 has an overall shape of two parallelogram link structures connected and arranged side by side on a horizontal line, and each of the parallelogram links A phase offset link piece 330 is disposed between them, and the two lifetime quadrilateral link structures have a structure in which they share the phase offset link piece 330 with each other. At this time, the vertical position of the link coupling axis 331 of the phase offset link piece 330 is located below the coupling axes 341 and 351 of the other links on the left and right.

More specifically, each of the raising and lowering link modules 300 has an upper link frame 310 having a certain length on the left and right and a plurality of coupling ribs 311, 312, and 313 for linking the links protruding downward. , and the upper link frame 310 and the lower link frame 320, which have a structure that is entirely opposed to each other and are disposed below the upper link frame 310 and linked together.

”와 “

”의 형상을 가지며, 이에 따라 상기 하부 링크 프레임(320)의 단면 내부에 서보 모터가 설치 가능하다.The longitudinal cross-sectional shapes of the upper link frame 310 and the lower link frame 320 in the direction perpendicular to the longitudinal direction are respectively “

"and "

It has the shape of “, and accordingly, a servo motor can be installed inside the cross section of the lower link frame 320.

At this time, the lower link frame 320 is formed with coupling ribs (no reference numerals) in the same shape as the coupling ribs 311, 312, and 313 of the upper link frame 310, as shown in FIGS. 2 and 3. Alternatively, the same function as a parallelogram link can be performed by forming only a coupling hole (no reference numeral) instead of a coupling rib in the lower link frame 320. For detailed information about the structure of the lower link frame 320, The explanation will be omitted.

In addition, a plurality of link pieces (330, 340, 350) are coupled between each coupling rib (311, 312, 313) of the upper and lower link frames (310, 320). First, the middle coupling rib (311) The phase offset link piece 330, whose vertical position of the coupling shaft 331 is located lower than that of the other coupling axes 341 and 351 adjacent to the left and right, is coupled.

In addition, the first link piece 340 is coupled to the coupling rib 312 formed at the left end of the phase offset link piece 330, and the second link piece 340 is coupled to the coupling rib 313 at the right end of the phase offset link piece 330. The link piece 350 is hinged. At this time, each coupling axis 341 and 351 of the first link piece 340 and the second link piece 350 is located above the coupling axis 331 of the above-described phase offset link piece 330.

In addition, each of the link pieces 330, 340, and 350, that is, the phase offset link pieces 330a and 330b, the first link pieces 340a and 340b, and the second link pieces 350a and 350b, are all two pairs. It is divided into two parts, one on the left and the other, at a certain interval to form a . Accordingly, when the upper link frame 310 is linked left and right on the lower link frame 320, it is stably supported without shaking in the side perpendicular to the left and right movement direction of the link so that the link can be moved.

At this time, as described above, among the coupling ribs 311, 312, and 313 of the upper link frame 310, the coupling rib 311 to which the center phase offset link piece 330 is coupled is connected to the other coupling ribs 312 and 313. ) is formed to be longer in length downward. Accordingly, the vertical position of the center coupling axis 331 is located lower than the other coupling axes 341 and 351 on the left and right.

In addition, as described above, a servo motor 390 is installed in the lower link frame 320, and the rotation axis of the servo motor 390 is coupled to the phase offset link piece 330 to function as a drive shaft. Therefore, as the phase offset link piece 330 is driven left and right by the electric force of the servo motor 390, the first link piece 340 and the second link piece 350 linked thereto are also simultaneously driven left and right. I get to exercise.

In addition, a bed piece 380 is further provided on the upper surface of each upper link frame 310 to support the load of the body. The bed piece 380 may be, for example, a cushion material in the form of a sponge with a waterproof coating finished on the outside, or it may be made of a hard wood material without a cushioning feel.

Meanwhile, Figure 4 is an enlarged perspective view of the main part of the lifting and lowering link module according to another embodiment of the present invention, and Figure 5 is an exploded perspective view of Figure 4. FIGS. 4 and 5 are other embodiments of FIGS. 2 and 3 discussed above, and illustrate that the raising/lowering link module of the present invention is implemented in the form of a quadruple parallelogram link.

More specifically, the quadruple parallelogram link has a structure in which three links are shared between each parallelogram link, and has a third link piece 360 and a fourth link piece 370 in the structure of the double parallelogram link described above. ) has an added configuration. Accordingly, coupling ribs 314 and 315 and coupling shafts 361 and 371 for link coupling the third and fourth link pieces 360 and 370 are further formed in the upper link frame 310, respectively.

Therefore, as seen in one embodiment, the phase offset link piece 330 is driven according to the driving of the servo motor 390 coupled to the satellite offset link piece 330, and accordingly, the phase offset link piece 330 The link-coupled first to fourth link pieces 340, 350, 360, and 370 are also moved simultaneously.

The quadruple parallelogram link structure is supported by more link pieces than the double parallelogram link structure, so it is a structure with higher stability in terms of load support and operational reliability.

Figure 6 is a schematic state diagram for explaining the link operation of the lifting and lowering link module of Figure 4, where (a) is the normal motion state in the case of a single parallelogram link, and (b) is the abnormal state due to the occurrence of the turning point in (a). The movement state (c) is a normal movement state in which the occurrence of turning points is prevented by applying a double parallelogram link according to the present invention.

Hereinafter, looking at the link operation of the lifting and lowering link module according to the present invention with reference to FIG. 6, FIG. 6a attached first illustrates the case of a single parallelogram link to which the present invention is not applied. In this case, in the normal motion state, each link maintains the overall structure of a parallelogram link and mostly performs normal motion.

However, as shown in FIG. 6B, the single parallelogram link structure of FIG. 6A may occasionally have a change point problem in which the driven link does not properly follow the unidirectional movement of the drive link.

Here, the turning point is a phenomenon in which all links are placed in a straight line as shown in FIG. 6b. When the turning point occurs, the movement of the output link becomes unpredictable. In this case, unlike the normal movement in FIG. 6a, a rattling noise occurs during link movement. Abnormal movements that cause shock and vibration occur.

Accordingly, it is proposed that the link in the lifting and lowering link module according to the present invention be a multi-parallelogram link in the form of at least two or more parallelogram links installed in order to prevent the occurrence of such a turning point.

As an example of such a multiple parallelogram link, a double parallelogram link may be applied as previously seen in FIGS. 2 and 3, an example of which is schematically shown in FIG. 6C.

In the double parallelogram link shown in FIG. 6C, the shared link located in the center, that is, the coupling axis 331 of the phase offset link piece 330 is located below the horizontal line than the coupling axes 341 and 351 of the other links on the left and right. It has the form of a located phase offset link.

Therefore, during the circular motion of the double parallelogram link, the occurrence of a turning point is prevented by the phase offset link piece 330, which has the effect of preventing the occurrence of abnormal motion.

Meanwhile, when the phase offset link piece 330 is erected vertically, the upper link frame 310 is positioned at the highest point, and at this time, the lifting link module 300 is raised.

On the other hand, when the phase offset link piece 330 is rotated left and right, the upper link frame 310 is positioned at the lowest point, and accordingly, the lifting link module 300 is lowered.

Therefore, it is possible to independently control the raising and lowering of each lifting link module 300 as described above, and accordingly, the upper link frame 310 and the bed piece 380 of each lifting link module 300 ) can change its shape so that its upper surface forms a flat surface side by side on a horizontal plane or forms a concave and convex surface.

Accordingly, in the case of a patient who has to lie in bed for a long time, the physical condition must change periodically or depending on the situation. By independently controlling the raising or lowering motion of each lifting and lowering link module of the present invention, a specific body part of the patient is affected by body weight. Serious side effects such as bedsores, which can be caused by continuous pressure that interferes with blood circulation or lack of air contact with the skin, can be prevented.

Meanwhile, in FIG. 6C, only the case of a double parallelogram link is illustrated, but the application of multiple parallelogram links is also possible. For example, as in other embodiments of the present invention discussed in FIGS. 4 and 5 described above, it is possible to apply a quadruple parallelogram link, and in this case, it not only supports the load more firmly than the double parallelogram link, but also suppresses the occurrence of turning points more clearly. This can achieve the effect of improving the reliability of operation.

Figure 7 is a schematic diagram showing the operation mechanism of the lifting and lowering link module according to the present invention.

Hereinafter, the operating mechanism of the lifting and lowering link module 300 according to the present invention will be described with reference to FIG. 7. The servo motor 390 receives an input as a rotation angle, and the link piece 330 connected to the servo motor 390, The height value (h) of the upper link frame 310 is determined according to the length (r) of 340 and 350).

Additionally, the required rotation angle of the servo motor 390 can be obtained by substituting the desired operating height into Equations 1 and 2 below.

(Formula 1)

(Formula 2)

here is the rotation angle of the lifting and lowering link module 300, is the rotation radius of the lifting and lowering link module 300, and is the height (vertical position) of the lifting link module 300, h1 is the initial vertical position where the lifting link module 300 is parallel, and h2 is the state in which the lifting link module 300 is lowered by △h. It is a vertical position.

In the method of controlling a medical robot bed for bedsore prevention using a body pressure sensor of the present invention, a plurality of raising and lowering link modules 300, the raising and lowering of which are independently controlled by parallelogram links, are arranged adjacent and parallel on the upper surface of the bed support, The operation of each lifting and lowering link module is controlled by a servo motor 390.

To this end, first, body pressure sensing information for each part of the human body applied to each lifting link module 300 is constantly collected through the body pressure sensor 1510 provided in each lifting link module 300 and sent to the operation control unit. send.

Next, the operation control unit 1200 reads the body pressure sensing information collected from the body pressure sensor 1510 of each of the plurality of lifting link modules 300 and transmits it from the body pressure sensor 1510 of the specific lifting link module 300. When the body pressure sensing information is close to 32 mmHg, which is the bedsore critical pressure at which bedsores can occur, the specific lifting and lowering link module 300 approaching the bedsore critical pressure is In the initial first vertical position (h1) where all lifting link modules 300, including 300, are parallel, only a specific lifting link module 300 that is close to the bedsore threshold pressure is moved to the first vertical position (h1). After being lowered to a relatively lower second vertical position (h2), the operation is stopped for a set dwell time.

Next, after the predetermined residence time has elapsed, each lifting and lowering link is raised by raising the specific lifting and lowering link module 300, which was stopped at the second vertical position (h1), back to the original first vertical position (h1). The raising and lowering motion and vertical position of the module 300 are independently controlled according to body pressure sensing information.

For example, the constant residence time may be set to 5 seconds or more in consideration of the time when the raising/lowering link module 300 goes down and the time when body pressure stabilizes after going down.

Figure 8 is a block diagram showing the control system of the bedsore prevention robot bed using the body pressure sensor of the present invention.

The control system 1000 of the present invention uses a user interface unit 1100, an operation control unit 1200, a host interface unit 1300, and a servo motor 1410 provided in each of the lifting and lowering link modules 300 to provide wired and wireless communication. It includes a multiple servo communication unit 1400 connected through wired and wireless communication, and a multiple sensor communication unit 1500 connected to the body pressure sensor 1510 and the sensor controller 1520 provided in each raising and lowering link module 300 through wired and wireless communication. You can.

Additionally, the control system 1000 may further include a sensor signal processing unit 1600 for processing the body pressure sensor signal of the body pressure sensor 1510.

According to one embodiment, the host interface unit 1100, the multi-servo communication unit 1400, and the multi-sensor communication unit 1500 may be connected through CAN (Controller Area Network) communication.

More specifically, the control system 1000 of the present invention includes 16 servo motor drivers 1420 for driving 16 lifting and lowering link modules 300 and a user interface unit connected to them through CAN (Controller Area Network) communication. It may be configured to include (1100), an operation control unit (1200), and a host interface unit (1300).

At this time, the user interface unit 1100 may be a teach pendant that indicates the operation mode of the bed.

Additionally, the CAN (Controller Area Network) communication is a standard communication standard designed to enable microcontrollers or devices to communicate with each other in a vehicle without a host computer.

According to one embodiment, the servo motor 1410 of the present invention may use 16 three-phase BLDC motors, and the servo motor driver 1420 for driving the servo motors 1410 up and down respectively uses a Hall sensor signal. A driver using a square wave driving method may be used.

For example, the servo motor driver 1420 may be mounted on each raising/lowering link module 300, and the host interface unit 1300 that communicates with the servo motor driver 1420 has two CAN communication ports and one May include RS485 communication port.

Additionally, the servo motor driver 1420 is capable of position control or speed control, and the position control and speed control modes can be set in real time using CAN messages. Additionally, ID recognition of the 16 servo motor drivers 1420 can be set sequentially using the I/O of each driver 1420.

Here, the BLDC servo motor 1410 is capable of sufficient position control only with signal information from the Hall sensor, so an algorithm for calculating position information with a three-phase Hall sensor is installed in the control system of the present invention, and CAN communication and RS485 communication are supported. The hardware of the servo motor driver 1420 can be configured to do this.

The operation control unit 1200 transmits position and speed control commands to the servo motor driver 1420 through CAN communication of the host interface unit 1300, and operates each servo motor 1410 by the servo motor driver 1420. Performs lifting and lowering movements and vertical positions.

According to one embodiment, the body pressure sensor 1510 may use an FSR-type thin film body pressure sensor. The body pressure sensor 1510 is mounted on each raising/lowering link module, and M body pressure sensors 1510 are connected to the sensor controller 1520. Then, the N sensor controllers 1520 transmit NM body pressure sensing information to the motion control unit 1200 through CAN communication, and the larger the NM (the greater the number of NMs), the greater the resolution of the body pressure sensing map.

However, it is desirable that the number of N and M is limited to an appropriate number for physical and practical reasons, and the body pressure sensor is calibrated before use to ensure that the number is 0. It can be configured to transmit body pressure sensing information of 80mmHg to the motion control unit.

Accordingly, when a control command is transmitted from the operation control unit 1200 to the servo motor driver 1420 installed in each of the 16 lifting link modules 300 through CAN communication, the servo motor driver 1420 operates on each lifting link. By controlling the module 300, it is independently raised and lowered to prevent bedsores.

In the present invention, as an operation control unit to independently control the raising/lowering and vertical position of the servo motor, a PI control type or an IP control type operation control unit can be used.

The PI control method generates an output proportional to the error between the command value and the measured value and the integral value of the error, while the IP control method generates an output proportional to the measured value and the integral value of the error between the command value and the measured value.

In the case of an IP controller, since there is no zero point in the transfer function, it is easy to set the control gain to achieve desired characteristics such as overshoot and stabilization time, and based on the same size of overshoot, the gain is larger than the PI control method. can do. In other words, the bandwidth can be increased, resulting in better response characteristics to disturbance.

Figure 9 is a block diagram of an operation control unit of the PI (Proportional-Integral) control method according to an embodiment of the present invention.

The vertical position movement amount (△h, see FIG. 7) of the raising/lowering link module can be modeled as being adjusted for the difference between the current body pressure and the critical body pressure (32 mmHg).

Assuming that the motion control unit of the PI control method is a first-order system, if expressed as a closed loop transfer function, it is expressed as Equation 3 below.

(Formula 3)

(Formula 4)

Here, Pmi is the maximum pressure of the ith raising/lowering link module, kp is the proportional term, ki is the integral term,

In the case of the PI control operation control unit in Equation 4 above, There is a zero point, and the size of overshoot increases due to the influence of this zero point. Therefore, the problem of overshoot response due to this zero point in the PI control system can be solved by using an IP control type motion control unit.

Figure 10 is a block diagram of an operation control unit of the IP (Integral-Proportional) control method according to another embodiment of the present invention.

Unlike the PI control type motion control unit, which proportionally controls the body pressure error (e), the IP control type motion control unit performs proportional control on the output body pressure sensing information.

If the block diagram of FIG. 10 is expressed as a transfer function, it is expressed as Equation 5 below.

(Formula 5)

In the operation control unit of the IP control method in Equation 5, the zero point of the PI control method is removed, enabling control to reduce the overshoot.

Experimental example of control performance of PI control method and IP control method

In this experimental example, an experiment was performed by applying the motion controller 1200 of the PI control method and the IP control method, respectively, to control the error (e) between the body pressure applied to each raising and lowering link module 300 and the bedsore threshold pressure. . The height (h, vertical position) of the raising/lowering link module 300 was controlled by the motion control unit 1200 of the PI or IP control method.

And the maximum body pressure in each lifting and lowering link module 300 is calculated by Equation 6 below.

(Formula 6)

Here, Pmi is the maximum pressure of the ith lifting link module, Pij is the body pressure measured at the jth sensor of the ith lifting link module, and M is the number of body pressure sensors in each lowering link module.

At this time, if the maximum body pressure value exceeds 32mmHg, it exceeds the pressure ulcer critical pressure that can cause bedsores, and if it continues for a certain period of time, actual bedsores occur.

Additionally, the error ei can be calculated by Equation 7 below.

(Equation 7)

here, is the target pressure value, is the maximum pressure of key i, is the keyboard input, and the total error is calculated as follows.

Additionally, the total error can be calculated by Equation 8 below.

(Equation 8)

N is the number of ascending and descending link modules.

Adjust the height (h, vertical position) of the raising and lowering link module according to the above formula, and when a change in body pressure value occurs due to the changed height, The characteristics were compared and reviewed.

Through the above-described process, in this experiment, the motion control unit of the PI or IP control method is applied to adjust the height of the lifting and lowering link module, and the errors in each lifting and lowering link module are removed so that the total error converges to 0. was set as the experiment goal.

As the lifting link module is lowered, the body pressure applied to the lifting link module also decreases. However, if the lifting link module is lowered rapidly, it may cause strain to the patient, so the height compared to the surrounding lifting link modules It is desirable to control the height adjustment in the direction of reducing the car.

In this experiment, the lifting and lowering link module was lowered step by step, and the total error was reduced to 0 with minimal movement.

For example, considering the time when the lifting link module goes down and the time when body pressure stabilizes after going down, the timer period of the motion control unit was set to 5 seconds (sec) or more.

The parameter values of the operation control unit of the PI control method used in the experiment are shown in Table 1 below.

(mmHg) 0.5 0 32 0.5 One 32

In an experiment with the PI control motion control unit, body pressure control was tested on a medical robot bed equipped with a body pressure sensor in a supine position for an adult male weighing 175 cm and 88 kg. The experiment was divided into a case with only a proportional term (P control) and a case with a proportional-integral term (PI control).

Figure 11 is a graph showing the experimental results of the operation control unit of the PI control method.

As shown in Figure 11, it was confirmed that the total error converges to 0 more quickly because the PI control in the case of integral (I) control reduces the residual deviation.

Table 2 below is an experiment result table summarizing the numerical data of the PI control method. (In the following, the keyboard refers to the raising/lowering link module.)

Keyboard number Error before control (mmHg) Maximum body pressure before control (mmHg) Error after control (mmHg) Maximum body pressure after control
(mmHg) Keyboard height
(mm) One 0 0 0 0 0 2 0 0 0 0 0 3 0 13 0 14 0 4 0 0 0 5 0 5 0 17 0 15 0 6 -5 37 0 20 -4 7 0 0 0 0 0 8 0 0 0 4 0 9 0 28 0 16 0 10 -5 37 0 21 -3 11 0 0 0 0 0 12 0 20 0 16 0 13 0 23 0 14 0 14 -7 39 0 21 -18 15 -5 37 0 20 -5 16 0 0 0 0 0 17 -2 34 0 17 -14

Meanwhile, the parameter values of the operation control unit of the IP control method used in the experiment are shown in Table 3 below.

(mmHg) 0.3 0.3 32 0.3 1.2 32

Meanwhile, Figure 12 is a graph showing the experimental results of the operation control unit of the IP control method.

Comparing the experimental results of the PI and IP control methods, it was confirmed that the PI control method proportionally controls the error with the bedsore threshold pressure value, so the convergence time to 0 is faster.

On the other hand, IP control stably converges to 0, but takes slower time than the PI control method, and it was observed that the patient may not feel comfortable because the lifting and lowering link module continues to vibrate.

Therefore, as described above, a body pressure sensor is mounted on each lifting link module of a medical robot bed composed of a plurality of lifting link modules, and then each lifting link module is controlled by PI control and IP control according to the body pressure sensing information. The control performance experiments of the motion control units were separately conducted.

To this end, the body pressure of each part of the body is measured and feedback controlled through each body pressure sensor, and the body pressure detected by each raising/lowering link module is controlled to within the bedsore threshold pressure (32 mmHg), thereby combining the PI control method and the IP control method. By comparing and reviewing the number of operations of the lifting and lowering link modules until each converges to 0, the PI control method is more advantageous than the IP control method in terms of pressure control speed and movement amount of the lifting and lowering link module in the robot bed according to the present invention for removing bedsores. This was confirmed through experiment.

Therefore, the present invention, unlike the simple alternating raising and lowering method according to time commonly used in conventional bedsore mattresses or pneumatic cylinder-controlled medical beds, independently adjusts the body pressure applied differently to each body part without harming the comfort of the user with impaired mobility. The effect of distributed control could be confirmed.

In addition, the present invention is not limited to just one embodiment described above, and the same effect can be created even when changing the detailed configuration, number, and arrangement structure of the device, so those skilled in the art will understand the present invention. It is stated that addition, deletion, and modification of various configurations are possible within the scope of the technical idea.

100: bed frame 110: headboard
120: Footboard 130: Safety bar
200: Support frame 300: Elevating and lowering link module
310: upper link frame 320: lower link frame
330: Phase offset link section 340: First link section
350: 2nd link 360: 3rd link
370: Fourth Link 380: Bed
390: Servo motor 1000: Control system
1100: User interface unit 1200: Operation control unit
1300: Host interface unit 1400: Multi-servo communication unit
1410: Servo motor 1420: Servo motor driver
1500: Multi-sensor communication unit 1510: Body pressure sensor
1520: sensor controller 1600: sensor signal processing unit

Claims (7)

A pressure ulcer prevention medical robot is arranged on the upper surface of the bed base in parallel with a plurality of ascending and lowering link modules whose raising and lowering is independently controlled by parallelogram links, and the movement of each lifting and lowering link module is controlled by a servo motor. In the bed control method,
Body pressure sensing information for each part of the human body applied to each lifting and lowering link module is constantly collected and transmitted to the operation control unit through the body pressure sensor provided in each lifting and lowering link module,
The operation control unit reads the body pressure sensing information collected from the body pressure sensors of each of the plurality of lifting link modules and adjusts the body pressure sensing information transmitted from the body pressure sensor of a specific lifting link module to 32 mmHg, which is the pressure ulcer threshold pressure at which bedsores can occur. When approaching,
The pressure ulcer critical pressure at an initial first vertical position h1 in which all lowering link modules, including a specific lowering link module, are parallel immediately before a specific lowering link module approaching the pressure ulcer threshold pressure reaches the pressure ulcer critical pressure. Lowering only specific lifting and lowering link modules that are close to the first vertical position (h1) to a second vertical position (h2) that is relatively lower than the first vertical position (h1) and then stopping the operation for a preset certain residence time,
After the predetermined residence time has elapsed, the specific lifting and lowering link module that was stopped at the second vertical position (h2) is raised again to the original first vertical position (h1), thereby raising and lowering the lowering link module, and The vertical position is independently controlled based on body pressure sensing information,
Control method of medical robot bed for bedsore prevention using body pressure sensor. According to claim 1,
The operation control unit,
The maximum body pressure in each raising and lowering link module is calculated by Equation 1 below,
(Formula 1)
(Here, Pmi is the maximum pressure of the lowering link module i, Pij is the body pressure measured at the jth sensor of the ith lowering link module, and M is the number of body pressure sensors in each lowering link module.)
The error ei is calculated by Equation 2 below,
(Formula 2)
(here, is the target pressure value, is the maximum pressure of key i.)
The total error (e _RMS ) is calculated by Equation 3 below,
(Formula 3)
(Here, N is the number of ascending and descending link modules.)
The operation control unit independently controls the raising and lowering operation and vertical position of each lifting and lowering link module so that the total error value calculated by the above formula converges to 0.
Control method of medical robot bed for bedsore prevention using body pressure sensor. According to claim 1,
The operation control unit,
A motion control unit of the PI (Proportional-Integral) control method or the IP (Integral-Proportional) control method is used,
Control method of a medical robot bed for bedsore prevention using a body pressure sensor. According to claim 1,
The motion control unit is connected to the servo motor provided in each lifting and lowering link module through CAN (Controller Area Network) communication,
Control method of a medical robot bed for bedsore prevention using a body pressure sensor. According to claim 1,
The raising and lowering link module,
At least two or more parallelogram links are connected and arranged side by side on a horizontal line, and the link arranged between each parallelogram link has a multiple parallelogram link structure in which a single link is shared with each other,
Control method of a medical robot bed for bedsore prevention using a body pressure sensor. According to claim 5,
Among the links shared between the multiple parallelogram links, the link located in the center is a phase offset link whose vertical position of the coupling axis is located lower than the other links on the left and right,
Control method of a medical robot bed for bedsore prevention using a body pressure sensor. According to claim 6,
The phase offset link is a drive link combined with a servo motor,
Control method of a medical robot bed for bedsore prevention using a body pressure sensor.

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