KR20220129754A - Control method of medical robot bed for bedsore prevention using body pressure sensor - Google Patents

Abstract

The present invention relates to a control method for a medical robot bed for preventing bedsores using a body pressure sensor. According to the present invention, a plurality of elevating and lowering link modules whose elevating and lowering is independently controlled by a parallelogram link are disposed adjacent to and in parallel on an upper surface of a bed support unit, and operation of each of the elevating and lowering link modules is controlled by a servomotor. In addition, body pressure sensing information for each part of the human body applied to each elevating and lowering link module is constantly collected and transmitted to an operation control unit through a body pressure sensor provided in each elevating and lowering link module. The operation control unit reads the body pressure sensing information collected from the body pressure sensor of each of the plurality of elevating and lowering link modules. Accordingly, when the body pressure sensing information transmitted from the body pressure sensor of a specific elevating and lowering link module approaches 32mmHg, which is a critical pressure for bedsores which can cause bedsores, only the specific elevating and lowering link module approaching the critical pressure for bedsores is lowered from an initial first vertical position (h1), in which all elevating and lowering link modules including the specific elevating link module are parallel, to a second vertical position (h2) relatively lower than the first vertical position (h1), and is stopped during a preset stay time, just before the specific elevating and lowering link module approaching the critical pressure for bedsores reaches the critical pressure for bedsores. After the preset stay time elapses, the specific elevating and lowering link module stopped at the second vertical position (h2) is elevated to the original first vertical position (h1). Accordingly, the elevating and lowering operation and vertical position of each elevating and lowering link module are independently controlled according to the body pressure sensing information.

Description

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

The present invention relates to a control method of a medical robot bed for preventing bedsores using a body pressure sensor, and more particularly, to a multi-parallelogram link structure in which elevating and lowering are independently controlled in the form of an elevating link module along the bed surface of the bed. A medical robot for preventing bedsores using a body pressure sensor, which has an excellent prevention effect on bedsores and skin diseases by arranging a plurality of descending link modules adjacent to each other in parallel and appropriately controlling the ascending and descending motions of the ascending and descending link modules according to the patient's nursing situation. It relates to the control method of the bed.

In general, medical beds used in hospitals have a structure in which a backrest or a footrest can be rotated at a certain angle for patients with reduced mobility and can be folded. Alternatively, it is divided into an electric type that adjusts the angle of the backrest by electric force using a hydraulic cylinder.

The manual medical bed has the advantage of being inexpensive in terms of not requiring a separate electric device, but there is a problem in that it is difficult for the patient who is uncomfortable in movement to use it himself because it takes a lot of force to adjust the angle of the backrest.

For this reason, in recent years, even if the purchase cost is somewhat expensive, the electric bed that can adjust the angle of the backrest by the patient himself is preferred.

One example of such a conventional medical electric bed is disclosed in Korean Patent Registration No. 10-0621349 (hereinafter referred to as 'prior literature').

Referring to FIGS. 1 and 2 of the prior literature, the conventional electric medical bed is largely located in a bed frame 10 and the bed frame 10, and each of the backrests 21 and 21 are rotatably coupled to each other, and An operation module 20 including a leg support part 22 , a driving module 30 comprising a plurality of links rotatably coupled to the operation module 20 and driven by an external force, and the bed frame 10 ) is located at the bottom and consists of a power module 40 that provides an 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, and each of the first actuators 41 applies power so that the backrest 21 is tilted, and the second actuator 42 gives power so that the leg support 22 is tilted.

In addition, the backrest part 21 is located on the upper surface of the bed frame 10 , one end is rotatably coupled to the fixing part 50 provided in the bed frame 10 , and the other end is upward by the driving module 30 . is tilted One end of the thigh portion 22a is rotatably coupled to the other side of the fixed portion 50, the shin portion 22b has one end rotatably coupled to the other end of the thigh portion 22a, and the footrest portion 22c has one end with the femur ( 22a) is rotatably coupled to the other end. In this way, the leg support part 22 is configured so that the leg support part 22 is tilted upward by the driving module 30 coupled to the bed frame 10 .

However, in the conventional electric bed for medical use configured as described above, the mat part is divided into a backrest part, a waist part, a joint part, and a leg support part so that it can be driven up and down, causing a critically ill patient who is difficult to move the body or lifting the leg. Postural modifications necessary for back treatment and nursing activities are possible to some extent, but in the case of a patient who cannot move while lying in bed, a specific body part of the patient is pressed on the bed for a long time, resulting in poor blood circulation, and There was a serious problem accompanied by complications such as bedsores and skin diseases as they could not be contacted.

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

Accordingly, the present invention has been devised to solve the above problems, and the elevating link module of a multi-parallelogram link structure in which elevating and elevating link modules are independently controlled along the bed surface of the bed is adjacent to each other in parallel. To provide a control method of a medical robot bed for preventing bedsores using a body pressure sensor, which is excellent in preventing pressure ulcers and skin diseases by appropriately controlling the elevating and lowering operation of the elevating link modules according to the patient's nursing situation. aim to

According to an embodiment, a method for controlling a bed for pressure ulcer prevention medical robot using a body pressure sensor of the present invention for achieving the above object is a plurality of elevating and lowering in which the elevating and lowering are independently controlled by a parallelogram link on the upper surface of the bed support part. In the control method of a bedsore prevention medical robot bed in which link modules are adjacently arranged in parallel, and the operation of each elevating link module is controlled by a servo motor, each elevating link module through a body pressure sensor provided in the The body pressure sensing information for each part of the human body applied to the elevating link module is always 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 elevating link module to specify When the body pressure sensing information transmitted from the body pressure sensor of the elevating link module approaches 32 mmHg, which is the pressure sore threshold pressure at which pressure sores can occur, just before the specific elevation link module close to the pressure sore threshold pressure reaches the pressure sore threshold pressure In the initial first vertical position (h1) in which all elevating link modules including a specific elevating link module are parallel, only a specific elevating link module close to the pressure sore threshold pressure is relatively higher than the first vertical position (h1). After descending to a lower second vertical position (h2), the operation is stopped for a preset dwell time, and after the predetermined dwell time has elapsed, the specific elevating link module that has been stopped at the second vertical position (h1) By raising it back to the original first vertical position (h1), the elevating operation and vertical position of each elevating link module are independently controlled according to the body pressure sensing information.

In addition, according to an embodiment, the operation control unit,

The maximum body pressure in each elevating link module is calculated by Equation 1 below,

(수식 1)

(Formula 1)

(Where Pmi is the maximum pressure of the elevating link module i, Pij is the body pressure measured by the j-th sensor of the i-th elevating link module, and M is the number of body pressure sensors of each elevating link module.)

The error ei is calculated by Equation 2 below,

(수식 2)

(Equation 2)

는 목표 압력값,

는 건반 i의 최대 압력,

는 건반 입력이다.)(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,

(수식 3)

(Equation 3)

(Where N is the number of elevating link modules.)

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

In addition, according to an embodiment, the operation controller of the PI (Proportional-Integral) control method or the IP (Integral-Proportional) control method is used as the operation controller.

In addition, according to an embodiment, the operation control unit is connected to the servo motor provided in each elevating link module by CAN (Controller Area Network) communication.

In addition, according to an embodiment, the elevating link module, at least two or more parallelogram links are arranged to be connected side by side on a horizontal line, and the links arranged between each of the parallelogram links are multiple parallelograms sharing a single link with each other It has a quadrilateral link structure.

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

Also, according to an embodiment, the phase offset link is a drive link coupled with a servo motor.

The present invention, as described above, arranges a plurality of elevating link modules that are independently controlled in the form of elevating link modules along the bed surface in parallel and adjacent to each other, and the elevating link module according to the patient's treatment or nursing situation. Excellent medical care that can prevent serious side effects such as pressure sores and skin diseases that occur when the patient's body is pressed on the bed for a long time and blood circulation is not smooth or does not come in contact with air by properly controlling the elevating operation of the descending link modules It works.

1 is a perspective view showing the entire medical power bed of the present invention;
2 is an enlarged perspective view of the elevating link module according to an embodiment of the present invention;
3 is an exploded perspective view of FIG. 2
Figure 4 is an enlarged perspective view of the elevating link module according to another embodiment according to the present invention
5 is an exploded perspective view of FIG. 4 ;
6 is a schematic state diagram for explaining the link operation of the elevating link module of FIG. 4, (a) is a normal motion state in the case of a single parallelogram link, (b) is abnormal due to the occurrence of a switching point in (a) The motion state, (c) is a normal motion state in which the occurrence of a turning point is prevented by applying the double parallelogram link according to the present invention
7 is a schematic diagram showing the operating mechanism of the elevating link module according to the present invention
8 is a block diagram showing a control system of a control method of a medical robot bed for preventing bedsores using a body pressure sensor of the present invention.
9 is a block diagram of an operation controller of a PI (Proportional-Integral) control method according to an embodiment of the present invention;
10 is a block diagram of an operation controller of an IP (Integral-Proportional) control method according to an embodiment of the present invention;
11 is a graph showing the experimental results of the operation control unit of the PI control method;
12 is a graph showing the experimental results of the operation control unit of the IP control method;

The terms used herein are used only to describe specific embodiments, and are not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present specification, terms such as "comprise" or "have" to "include" are intended to designate that a feature, number, step, action, component, part, or combination thereof described in the present specification exists, but one It is to be understood that it does not preclude the possibility of the presence or addition of or more other features or numbers, steps, operations, components, parts, or combinations thereof.

Unless defined otherwise herein, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

Terms such as those defined in a commonly used dictionary should be interpreted as having a meaning consistent with the meaning in the context of the related art, and should not be interpreted in an ideal or excessively formal meaning unless explicitly defined in the present specification. shouldn't

Hereinafter, with reference to the accompanying drawings, the configuration and operation relationship of the medical power bed of the present invention will be described in detail as follows.

Figure 1 is a perspective view of the present invention as a whole medical power bed, Figure 2 is an enlarged perspective view of the elevating link module according to an embodiment according to the present invention, Figure 3 is an exploded perspective view of Figure 2 .

Hereinafter, a configuration of a medical power bed according to an embodiment of the present invention will be described with reference to FIGS. 1 to 3 .

First, the electric bed for medical use of the present invention is provided with a support frame 200 that can support the body for each part on the upper end of the bed frame 100 usually made of a steel structure. 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 , 230 . , 240) can be selectively adjusted for elevation or rotation angle.

For example, when a patient with poor movement is seated, the backrest 210 can be lifted upward, while a patient with uncomfortable legs raises the legrest 240 upwards, etc. This is possible.

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

On the other hand, as a characteristic component of the present invention, a plurality of elevating link modules in which elevating and lowering are independently controlled by a parallelogram link on the upper surface of each supporting unit 210 , 220 , 230 , 240 of the supporting frame 200 . 300 are adjacently arranged in parallel, and a servo motor 390 is coupled to one of the link coupling shafts of each elevating link module 300 to drive the link.

At this time, as each of the elevating link modules 300 is provided with one servo motor 390 separately, the elevating and lowering of each elevating link module 300 can be independently controlled by the servo motor 390. It is understandable that

Hereinafter, referring to FIGS. 2 and 3 , according to an embodiment, each of the elevating link modules 300 has a form in which two parallelogram link structures are connected and arranged side by side on a horizontal line as a whole. A phase offset link piece 330 is disposed therebetween, and the two lifelong quadrilateral link structures have a structure in which the phase offset link piece 330 is shared with each other. At this time, the phase offset link piece 330 is positioned below the link coupling shaft 331 of the vertical position than the coupling shafts 341 and 351 of the other links on the left and right.

More specifically, each of the elevating link modules 300 has an upper link frame 310 in which a plurality of coupling ribs 311, 312, 313 are integrally protruded for link coupling downward and having a predetermined length from side to side. , the upper link frame 310 and the lower link frame 320 has a structure opposite to each other as a whole and is disposed below the upper link frame 310 to be link-coupled.

”와 “

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

"Wow "

”, so that the servo motor can be installed inside the cross-section of the lower link frame 320 .

At this time, coupling ribs (no reference numerals) are formed in the lower link frame 320 in the same shape as the coupling ribs 311 , 312 , 313 of the upper link frame 310 as shown in FIGS. 2 and 3 . Alternatively, the lower link frame 320 can perform the same function as a parallelogram link even if only a coupling hole (no reference numeral) is formed instead of a coupling rib in the lower link frame 320. Details of the structure of the lower link frame 320 A description will be omitted.

In addition, a plurality of link pieces 330 , 340 , 350 are coupled between the respective coupling ribs 311 , 312 , 313 of the upper and lower link frames 310 and 320 . First, the central coupling rib 311 has The vertical position of the coupling shaft 331 is a phase offset link piece 330 positioned below the other coupling shafts 341 and 351 adjacent to the left and right are 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 right end coupling rib 313 of the phase offset link piece 330 . The link piece 350 is hinged. At this time, the coupling shafts 341 and 351 of the first link piece 340 and the second link piece 350 are located above the coupling shaft 331 of the phase offset link piece 330 described above.

In addition, each of the link pieces 330 , 340 , 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 and formed one by one on the left and right at regular intervals to achieve a . Accordingly, when the upper link frame 310 is linked to the left and right on the lower link frame 320, it is stably supported without shaking in a lateral direction perpendicular to the left and right movement direction of the link so that the link movement can be performed.

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

In addition, as described above, the servo motor 390 is installed inside the lower link frame 320 , and the rotation shaft of the servo motor 390 is coupled to the phase offset link piece 330 to function as a driving shaft. Therefore, as the phase offset link piece 330 is driven to the 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 linked to the left and right at the same time. get to exercise

In addition, a bed piece 380 for supporting a body load is further provided on the upper surface of each of the upper link frames 310 . The bed piece 380 may be, for example, a cushioning material in which a waterproof coating is finished on the outside of a sponge, or may be implemented as a hard wood material without a cushioning feeling.

Meanwhile, FIG. 4 is an enlarged perspective view of the elevating link module according to another embodiment of the present invention, and FIG. 5 is an exploded perspective view of FIG. 4 and 5 are other embodiments of FIGS. 2 and 3 discussed above, illustrating that the elevating 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 the third link piece 360 and the fourth link piece 370 are the structures of the double parallelogram link discussed above. ) has been added. 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 shown in the 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 is Link-coupled first to fourth link pieces (340, 350, 360, 370) are also simultaneously moved together.

The quadruple parallelogram link structure has a higher stability in terms of load bearing and operation reliability as it is supported by more link pieces than the double parallelogram link structure.

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

Hereinafter, referring to FIG. 6, referring to the link operation of the elevating link module according to the present invention, the attached FIG. 6a illustrates a case of a single parallelogram link to which the present invention is not applied. In this case, in the normal motion state, most of the links perform normal motion while maintaining the structure of the parallelogram link as a whole.

However, as shown in FIG. 6B , in the single parallelogram link structure of FIG. 6A , a change point problem in which the driven link does not properly follow the driving link in one direction may occasionally occur.

Here, the turning point is a phenomenon in which all links are placed on a straight line as in FIG. 6B. When the turning point occurs, the movement of the output link becomes unpredictable. In this case, unlike the normal motion in FIG. Abnormal motion that generates shock and vibration occurs.

Accordingly, as for the link in the elevating link module according to the present invention, the application of multiple parallelogram links of a type in which at least two or more parallelogram links are connected and installed is proposed in order to prevent the occurrence of such a turning point.

As an embodiment of such a multi-parallelogram link, a double parallelogram link may be applied as previously described in FIGS. 2 and 3 , an example of which is schematically illustrated in FIG. 6C .

The double parallelogram link shown in FIG. 6c has a shared link located in the middle, that is, the coupling axis 331 of the phase offset link piece 330 is lower on 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 phase-offset link located.

Therefore, during the circular motion of the double parallelogram link, the occurrence of the turning point is prevented by the phase offset link piece 330, and accordingly, the occurrence of the abnormal motion is prevented.

On the other hand, in a state in which the phase offset link piece 330 is vertically erected, the upper link frame 310 is in a state positioned at the highest point, and at this time, the elevating link module 300 is in an elevated state.

On the other hand, in the state in which 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 elevating link module 300 is in a lowered state.

Therefore, it is possible to independently control the rise and fall of each elevating link module 300 as described above, and accordingly, the upper link frame 310 and the bed piece 380 of each elevating link module 300 , respectively. ), it is possible to change the shape so that the upper surface of it forms a plane side by side on a horizontal plane or a convex and convex surface.

Accordingly, in the case of a patient who has to lie in bed for a long time, the body condition must be changed periodically or by situation. It is possible to prevent serious side effects such as pressure sores, which may be caused by continuous compression, which impedes blood circulation or may not be able to contact the skin with air.

Meanwhile, although only the case of the double parallelogram link is exemplified in FIG. 6C, the application of the multiple parallelogram link is also possible. For example, it is possible to apply a quadruple parallelogram link as in the other embodiments of the present invention as described in FIGS. 4 and 5, and in this case, more robust load support than the double parallelogram link, as well as more reliable suppression of the occurrence of a turning point This can be achieved, and accordingly, it is possible to obtain the effect of improving the reliability of the operation.

7 is a schematic diagram showing an operating mechanism of the elevating link module according to the present invention.

Hereinafter, the operation mechanism of the elevating link module 300 according to the present invention will be described with reference to FIG. 7 , the servo motor 390 receives an input at 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 the 340 and 350 .

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

(수식 1)

(Formula 1)

(수식 2)

(Equation 2)

는 승하강 링크 모듈(300)의 회전각도이고,

은 승하강 링크 모듈(300)의 회전반경, 그리고

는 승하강 링크 모듈(300)의 높이(수직 위치)로서, h1은 승하강 링크 모듈(300)이 평행한 초기의 수직 위치, h2는 승하강 링크 모듈(300)이 △h만큼 하강한 상태의 수직 위치이다.here

is the rotation angle of the elevating link module 300,

is the radius of rotation of the elevating link module 300, and

is the height (vertical position) of the elevating link module 300, h1 is the initial vertical position in which the elevating link module 300 is parallel, h2 is the elevating link module 300 is lowered by Δh vertical position.

In the control method of the medical robot bed for bedsore prevention using the body pressure sensor of the present invention, a plurality of elevating link modules 300, each of which elevating and lowering independently controlled by a parallelogram link, is adjacent to and parallel to the upper surface of the bed support part, The operation of each elevating link module is controlled by a servo motor 390 .

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

Then, the operation control unit 1200 reads the body pressure sensing information collected from the body pressure sensor 1510 of each elevating link module 300 and transmits it from the body pressure sensor 1510 of the specific elevating link module 300 . When the body pressure sensing information is close to 32 mmHg, which is a pressure sore threshold pressure at which pressure sores can occur, a specific elevation link module 300 close to the pressure sore threshold pressure reaches the pressure sore threshold pressure. In the initial first vertical position (h1) in which all elevating link modules 300 including 300 are parallel, only a specific elevating link module 300 close to the pressure sore threshold pressure in the first vertical position (h1) After descending to a relatively lower second vertical position (h2), the operation is stopped for a preset dwell time.

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

For example, the period of the predetermined residence time may be set to 5 seconds (sec) or more in consideration of the time for the elevating link module 300 to descend and the time for the body pressure to be stabilized after descending.

8 is a block diagram illustrating a control system for a bed ulcer prevention robot bed using a body pressure sensor of the present invention.

The control system 1000 of the present invention performs wired/wireless communication with the user interface unit 1100 , the operation control unit 1200 , the host interface unit 1300 , and the servo motor 1410 provided in each elevating link module 300 . A multi-servo communication unit 1400 that connects through, and a multi-sensor communication unit 1500 that connects the body pressure sensor 1510 and the sensor controller 1520 provided in each elevating link module 300 through wired/wireless communication. can

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

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

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

At this time, the user interface unit 1100 may be a teach pendant (Teach Pendant) instructing the operation mode of the bed.

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

According to an 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 motor 1410 up and down, respectively, receives a Hall sensor signal. A used square wave driving type driver may be used.

For example, the servo motor driver 1420 may be mounted on each elevating link module 300 , and the host interface unit 1300 communicating with the servo motor driver 1420 includes two CAN communication ports and one It may include an RS485 communication port.

In addition, the servo motor driver 1420 may perform position control or speed control, and may set the position control and speed control mode in real time as a CAN message. In addition, ID recognition of 16 servo motor drivers 1420 may be sequentially set using I/O of each driver 1420 .

Here, since the BLDC servo motor 1410 is capable of sufficient position control only with the signal information of the Hall sensor, the algorithm for calculating the position information with the three-phase Hall sensor is mounted in the control system of the present invention, and CAN communication and RS485 communication support are provided. 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 to each servo motor 1410 by the servo motor driver 1420. It will perform the lifting and lowering motion and vertical position.

According to an embodiment, the body pressure sensor 1510 may be an FSR type thin film body pressure sensor. The body pressure sensor 1510 is mounted on each elevating 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 operation controller 1200 through CAN communication, and the larger the NM (the larger the number of NMs), the higher the resolution of the body pressure sensing map.

80mmHg의 체압 센싱 정보를 동작 제어부로 전송하도록 구성될 수 있다.However, it is preferable that N and M are limited to an appropriate number for physical and practical reasons, and the body pressure sensor is calibrated before use to 0

It may be configured to transmit body pressure sensing information of 80 mmHg to the operation 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 elevating link modules 300 through CAN communication, the servo motor driver 1420 performs each elevating link By controlling the module 300, it is driven up and down independently to prevent bedsores.

In the present invention, as the operation control unit for independently controlling the elevation and vertical position of the servo motor, the operation control unit of the PI control method and the IP control method may be used.

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

In the case of IP controller, since there is no zero point in the transfer function, it is easy to set the control gain so that overshoot and stabilization time are desired characteristics. can do. That is, since the bandwidth can be increased, better response characteristics to disturbance are obtained.

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

The vertical position movement amount (Δh, see FIG. 7) of the elevating 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 operation control unit of the PI control method is a primary system, it is expressed as a closed loop transfer function as shown in Equation 3 below.

(수식 3)

(Equation 3)

(수식 4)

(Equation 4)

Here, Pmi is the maximum pressure of the i-th elevating link module, kp is a proportional term, ki is an integral term,

에 영점이 존재하고 있으며, 이 영점의 영향으로 인해 오버슈트(overshoot)의 크기가 증가한다. 그러므로 PI 제어 시스템에서 이러한 영점에 의한 오버슈트 응답의 문제점은 IP 제어 방식의 동작 제어부를 사용하면 해결할 수 있다.In the case of the operation control unit of the PI control method in Equation 4,

There is a zero point in , and the size of the overshoot increases due to the influence of this zero point. Therefore, the problem of the overshoot response due to the zero point in the PI control system can be solved by using the operation control unit of the IP control method.

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

The operation controller of the IP control method performs proportional control on the output body pressure sensing information, unlike the operation controller of the PI control method that proportionally controls the body pressure error (e).

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

(수식 5)

(Equation 5)

In the operation control unit of the IP control method of Equation 5, the zero point of the PI control method is removed, so that the overshoot becomes small.

Example of control performance of PI control method and IP control method

In this experimental example, in order to control the error (e) between the body pressure applied to each elevating link module 300 and the pressure sore threshold pressure, the operation control unit 1200 of the PI control method and the IP control method was applied to each of the experiments. . The height (h, vertical position) of the elevating link module 300 was controlled by the operation control unit 1200 of the PI or IP control method.

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

(수식 6)

(Equation 6)

Here, Pmi is the maximum pressure of the i-th elevating link module, Pij is the body pressure measured by the j-th sensor of the i-th elevating link module, and M is the number of body pressure sensors of each elevating link module.

At this time, when the maximum body pressure exceeds 32 mmHg, the pressure sore at which a pressure sore can occur is exceeded, and when a predetermined period of time continues, a pressure sore actually occurs.

Also, the error ei may be calculated by Equation 7 below.

(수식 7)

(Equation 7)

는 목표 압력값,

는 건반 i의 최대 압력,

는 건반 입력이고 이때, 전체 에러는 다음과 같이 계산한다.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.

Also, the total error may be calculated by Equation 8 below.

(수식 8)

(Equation 8)

Where N is the number of elevating link modules.

의 특성을 비교 검토하였다.Adjusts the height (h, vertical position) of the elevating link module according to the above formula,

characteristics were compared and reviewed.

Through the above-described process, in this experiment, the height of the elevating link module is adjusted by applying the operation control unit of the PI or IP control method, respectively, and the error applied to each elevating link module is removed, so that the total error converges to 0. was set as the experimental goal.

As the elevating link module is lowered, the body pressure applied to the elevating link module also decreases as the elevating link module is lowered. It is desirable to control the height adjustment in the direction of reducing the difference.

In this experiment, it was compared and reviewed that the elevating link module descends step by step and the total error becomes 0 with minimal movement.

For example, the timer period of the operation control unit was set to 5 seconds or more in consideration of the time for the elevating link module to descend and the time for body pressure to be stabilized after descending.

Table 1 below shows the parameter values of the motion controller of the PI control method used in the experiment.

(mmHg) 0.5 0 32 0.5 One 32

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

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

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

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

key 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 operation control parameter values 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, FIG. 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 time to converge to zero was faster in the PI control method because the error with the pressure ulcer threshold was proportionally controlled.

On the other hand, we observed that IP control stably converges to 0, but it takes longer than PI control method.

Therefore, as described above, after mounting a body pressure sensor for each elevating link module of the medical robot bed composed of a plurality of elevating link modules, the elevating link module is controlled by PI control and IP control method according to body pressure sensing information. Each of the control performance experiments of the motion controller was performed separately.

To this end, the PI control method and the IP control method are divided by measuring the body pressure for each part of the body through each body pressure sensor and feedback control thereof, and controlling the body pressure detected by each elevating link module to be within the pressure sore threshold pressure (32mmHg). By comparing and examining the number of operations of the elevating link module until each converges to 0, the PI control method is more advantageous than the IP control method in the pressure control speed or the movement amount of the elevating link module in the robot bed according to the present invention for the removal of bedsores. It was confirmed through an experiment.

Therefore, the present invention independently separates the body pressure applied differently for each body part without compromising the user's comfort, unlike the simple alternating lifting and lowering method according to time commonly used in conventional bedsore mattresses or pneumatic cylinder-controlled medical beds. It was possible to confirm the effect of being able to control the dispersion.

In addition, the present invention is not limited only by the above-described embodiment, and since it is possible to create the same effect even when changing the detailed configuration, number, and arrangement of the device, those of ordinary skill in the art will present the present invention It is specified that various additions, deletions, and modifications are possible within the scope of the technical idea of

100: bed frame 110: headboard
120: foot board 130: safety bar
200: support frame 300: elevating link module
310: upper link frame 320: lower link frame
330: phase offset link piece 340: first link piece
350: second link section 360: third link section
370: fourth link 380: bed
390: servo motor 1000: control system
1100: user interface unit 1200: operation control unit
1300: host interface unit 1400: multiple 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 medical robot for preventing bedsores in which a plurality of elevating link modules that are independently controlled by a parallelogram link on the upper surface of the bed support are adjacent and parallel to each other, and each elevating link module is controlled by a servo motor In the control method of the bed,
Through the body pressure sensor provided in each elevating link module, body pressure sensing information for each part of the human body applied to each elevating link module is constantly collected and transmitted to the operation control unit,
The operation control unit reads the body pressure sensing information collected from the body pressure sensors of each elevating link module, and the body pressure sensing information transmitted from the body pressure sensor of the specific elevating link module is set at 32 mmHg, which is a pressure sore threshold pressure at which pressure sores can occur. If close,
Immediately before the specific elevation link module approaching the pressure sore threshold pressure reaches the pressure sore threshold pressure, the pressure sore threshold pressure at the initial first vertical position (h1) in which all elevation link modules including the specific elevation link module are parallel. After lowering only a specific elevating link module close to the first vertical position (h1) to a relatively lower second vertical position (h2) than the first vertical position (h1) to stop the operation for a preset predetermined residence time,
After the predetermined residence time has elapsed, the elevating operation of each elevating link module and Independently controlling the vertical position according to the body pressure sensing information,
A method of controlling a bed for pressure ulcer prevention medical robot using a body pressure sensor. The method of claim 1,
The operation control unit,
The maximum body pressure in each elevating link module is calculated by Equation 1 below,

(Formula 1)
(Where Pmi is the maximum pressure of the elevating link module i, Pij is the body pressure measured by the j-th sensor of the i-th elevating link module, and M is the number of body pressure sensors of each elevating link module.)
The error ei is calculated by Equation 2 below,

(Equation 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,

(Equation 3)
(Where N is the number of elevating link modules.)
The operation control unit independently controls the elevating operation and vertical position of each elevating link module so that the total error value calculated by the above formula converges to 0,
A method of controlling a bed for pressure ulcer prevention medical robot using a body pressure sensor. The method of claim 1,
The operation control unit,
An operation control unit of a PI (Proportional-Integral) control method or an IP (Integral-Proportional) control method is used,
A method of controlling a bed for pressure ulcer prevention medical robot using a body pressure sensor. The method of claim 1,
The operation control unit is connected by CAN (Controller Area Network) communication with the servo motor provided in each elevating link module,
A method of controlling a bed for pressure ulcer prevention medical robot using a body pressure sensor. The method of claim 1,
The elevating link module,
At least two or more parallelogram links are connected side by side on a horizontal line, and the links disposed between each parallelogram links have a multi-parallelogram link structure that shares a single link with each other,
A method of controlling a bed for pressure ulcer prevention medical robot using a body pressure sensor. 6. The method of claim 5,
Among the links shared between the multiple parallelogram links, the link located in the middle is a phase offset link in which the vertical position of the coupling axis is lower than the other links on the left and right,
A method of controlling a bed for pressure ulcer prevention medical robot using a body pressure sensor. 7. The method of claim 6,
The phase offset link is a drive link coupled with a servo motor,
A method of controlling a bed for pressure ulcer prevention medical robot using a body pressure sensor.

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