KR20200133039A - Smart Sensor System - Google Patents

Abstract

The present invention relates to a smart sensor system for knee artificial joint surgery. More specifically, the present invention relates to a smart sensor system for knee artificial joint surgery, which can guide the pressure balance within the knee to be uniformly set regardless of experience of a doctor by accurately calculating and providing pressure information required for knee artificial joint surgery from a smart sensor inserted into an artificial joint.

Description

Smart sensor system for knee artificial joint surgery {Smart Sensor System}

The present invention relates to a smart sensor system for knee artificial joint surgery, and more particularly, by accurately calculating and providing pressure information necessary for knee artificial joint surgery from a smart sensor inserted into an artificial joint, pressure in the knee regardless of the doctor's experience. It relates to a smart sensor system for knee artificial joint surgery that can guide the balance to be set evenly.

In order to recover quickly after an artificial joint replacement surgery, it is important how elaborate the surgery was performed.In most cases, inserting an artificial joint according to the shape of the knee bone can be done at a level close to perfect, but the pressure in the knee can be controlled by adjusting the ligaments and tendons. The experience of the doctor has an absolute influence on the balance, and if the patient's knee pressure is adjusted incorrectly during the procedure, the patient will feel pain while adjusting to the pressure, which can reduce satisfaction. There was a limit to the perfect fit.

Therefore, regardless of the doctor's experience, whether or not the intra-knee pressure balance can be set evenly is the key to artificial joint replacement surgery.Therefore, a special sensor is inserted between the artificial joints to measure the pressure in each part of the knee to show the numerical value. Based on this, artificial joint replacement surgery using a smart sensor that can evenly match knee pressure by adjusting the ligaments of the knee deformed by arthritis is being introduced.

However, in order to set the intra-knee pressure balance evenly, the load/coordinate/angle must be accurately calculated when the sensor is inserted into the knee along with the artificial joint, but the geometric structure of the artificial joint and the data errors and errors sensed by the sensor Due to the lack of accuracy, it was difficult to set an accurate pressure balance.

As conceived to solve the above problems, an object of the present invention is to provide a uniform pressure balance within the knee regardless of the experience of the doctor by accurately calculating and providing pressure information required for knee artificial joint surgery from a smart sensor inserted into the artificial joint. It is to provide a smart sensor system for knee artificial joint surgery that can be guided so that it can be set properly.

In order to achieve the above object, the smart sensor system for knee arthroplasty surgery according to the present invention includes a smart sensor that is inserted into the artificial joint and senses data with a sensor that is pressure level information for each position of the artificial joint up and down; And a data calculating means for receiving the sensor raw data sensed from the smart sensor and calculating pressure information necessary for setting an artificial joint; The smart sensor checks the state of the battery, detects the sensor raw data, and transmits the detected sensor raw data to the data calculating means, and a battery connected to the sensor block to supply power required for the operation of the sensor block. It characterized in that it includes a block.

The sensor block is composed of a plurality of divided sensor cells, and includes a first sensor unit and a second sensor unit in which the same number of sensor cells are respectively arranged on the left and right sides for uniform setting of the left and right pressure balance of the artificial joint. Characterized in that.

The sensor block includes a sensor unit that senses sensor raw data, which is pressure level information for each upper and lower position of the artificial joint; An MCU controlling transmission of sensing data sensed from the sensor unit to a host; And an antenna for wirelessly transmitting the sensing data to a host under the control of the MCU; The MCU checks the state of the battery block, controls data transmission/reception through wireless communication with the data calculation unit, and transmits the sensor raw data sensed through the sensor unit to the data calculation unit when a preprocessing process is performed and a scan command is received. It characterized in that it controls wireless transmission.

If there is FW update information for the smart sensor, the data calculation means transmits it to the smart sensor, and when the power is powered on from the battery, the smart sensor receives the result of the battery check, and performs a preprocessing process for scanning the sensor unit. A sensor management module configured to perform, command a sensor scan through wireless communication with the smart sensor, and receive and manage sensor raw data detected through the sensor unit; Including a pre-processing process for the sensor raw data of each sensor cell received by the sensor management module, performing a force correction and matching process with Newton, and calculating coordinates and angles for the force correction values of each cell. It characterized in that it comprises a pressure information calculation module for calculating the pressure information.

The sensor management module includes: a system initialization including smart sensor information setting (version information/sensor-related information), I2C block initialization, BLE block initialization, WTD block initialization, ADC block initialization, and EEPROM block initialization; Initializing the boot loader SRAM for OTA FW update; System operation initialization including smart sensor initialization including smart sensor block initialization, sensor baseline initialization, pressure calibration parameter initialization, force matching to Newton parameter initialization, battery check, OTA FW update operation Performing a pretreatment process; When the preprocessing process is finished, a scan command is transmitted to the smart sensor.

The pressure information calculation module performs the pre-processing process, force correction, and force matching process with Newton; The pre-processing process checks whether the sensor raw data is first press or first release, sets an adaptive filter, filters the raw sensor data, and filters each sensor cell of the sensor unit. Calculating sensor variation data for; In the force correction process, an equation is calculated so that the amount of change in the sensor value according to the applied load becomes linear, but since the sensor unit is composed of a plurality of sensor cells and the amount of change curve of each cell is different, the force correction formula is input to calculate each cell. The current input value for data (sensor change data for each sensor cell) is checked, and if it is less than the boundary load, force correction is performed according to Equation 1-1 below, and if it is greater than the boundary load, the following Equation 1 Performing force correction by -2 to calculate output data (corrected sensor change data of each cell);

Equation 1-1: Y= A*(EXP(B*X)-EXP(C*X))

Equation 1-2: Y=(A+X)/(B+C*X**2)+D*X

In the force matching process, the output data in the force correction process becomes input data (corrected sensor change data of each cell), and the sum of the forces in the effective force region (ΣFValid) is calculated by Equation 2-1 below. And calculating the load (force) for each sensor cell of the sensor unit by matching the force with Newton by Equation 2-2 below using the sum of the forces (ΣFValid) as an applied load.

Equation 2-1: ΣFValid = fmax + fmax-1 + fmax-2

Equation 2-2: Y = A+B*X+C*X**2+D*X**3

In addition, the pressure information calculation module assumes that independent forces are applied to the left area (first sensor unit) and the right area (second sensor unit) of the sensor during the process of calculating the coordinates for the force correction value of each cell, and input With respect to the data (uncorrected sensor change data and corrected ΣFValid), it is checked whether ΣFValid in the left area is greater than the effective force, and if larger, left X,Y coordinates are calculated by Equation 3-1; For input data (uncorrected sensor change data and corrected ΣFValid), it is checked whether or not ΣFValid in the right area is greater than the effective force, and if larger, right X,Y coordinates are calculated by Equation 3-1;

Equation 3-1:

a. LX = Ratio * (LFx / ΣFLeft)

b. LY = Ratio * (LFy / ΣFLeft)

c. RX = Ratio * (RFx / ΣFRight)

d. RY = Ratio * (RFy / ΣFRight)

Calculating the angle between the two coordinates of the left and right areas; Radians are calculated by Equation 3-4 for the calculated left X,Y and right X,Y coordinates;

Equation 3-4: Radian = atan(dY/dX)

If the left ΣFValid and the right ΣFValid are greater than 0, the angle is calculated by Equation 3-5.

Equation 3-5: Angle = Radian * (180/PI)

Here, when the left X,Y coordinates and the right X,Y coordinates are calculated, the pressure information calculation module checks whether a correction parameter exists, and if the correction parameter exists, performs coordinate correction according to Equation 3-2. It characterized in that it further comprises the step of calculating the coordinates.

Equation 3-2: a. XCal_L = LeftParmX1 * X_Left + LeftParmX2 * Y_Left + LeftParmX3

b. YCal_L = LeftParmY1 * X_Left + LeftParmY2 * Y_Left + LeftParmY3

c. XCal_R = RightParmX1 * X_Left + RightParmX2 * Y_Left + RightParmX3

d. YCal_R = RightParmY1 * X_Left + RightParmY2 * Y_Left + RightParmY3

Here, RightParmX1, RightParmX2, RightParmX3, RightParmY1, RightParmY2 and RightParmY3 are correction parameters.

As described above, the smart sensor system for knee artificial joint surgery according to the present invention precisely corrects the sensor raw data for the force (load) of the sensor cell detected according to the environmental conditions of the knee artificial joint, and the force (load) and coordinates And since the angle can be calculated and provided to the medical staff, regardless of the doctor's experience, it is possible to guide the pressure balance in the knee to be uniformly set, resulting in an excellent effect of increasing the reliability of knee artificial joint surgery.

1 is a perspective view schematically showing a smart sensor according to a preferred embodiment of the present invention,
2 is a block diagram schematically showing the structure of the smart sensor of FIG. 1.
3 is a perspective view schematically illustrating an artificial joint equipped with a smart sensor of FIG. 1.
4 is a system configuration diagram schematically showing a smart sensor system for knee artificial joint surgery according to a preferred embodiment of the present invention.
5 is a flowchart schematically showing a method of calculating pressure information for knee artificial joint surgery using a smart sensor according to a preferred embodiment of the present invention.
6 is a flowchart schematically illustrating a battery check method of a smart sensor according to the present invention.
7 is a flowchart schematically illustrating a pre-processing process for raw sensor data according to an exemplary embodiment of the present invention.
8A is a flow chart schematically showing a force correction process according to a preferred embodiment of the present invention, and FIG. 8B is a flow chart schematically showing a force matching process with Newtons according to a preferred embodiment of the present invention.
9 schematically shows a change amount curve for each load according to a preferred embodiment of the present invention.
10 schematically illustrates a simulation graph according to a force correction process according to a preferred embodiment of the present invention.
11A schematically shows a coordinate calculation process according to a preferred embodiment of the present invention, FIG. 11B schematically shows a coordinate correction process, and FIG. 11C is a flowchart schematically showing an angle calculation process.
12 schematically shows the force distribution of the sensor cell of the left first sensor unit according to a preferred embodiment of the present invention.
13 schematically shows an equation of a coordinate correction algorithm according to a preferred embodiment of the present invention.
13 schematically shows a coordinate system for calculating an angle according to a preferred embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

1 is a perspective view schematically showing a smart sensor according to a preferred embodiment of the present invention, and FIG. 2 is a block diagram schematically showing the structure of the smart sensor of FIG. 1.

1 and 2, the smart sensor 10 according to the present invention checks the state of the battery, detects sensor raw data, which is pressure magnitude information for each upper and lower position of the artificial joint, and converts the detected sensor data into the data calculation means. It may be configured to include a battery block 120 connected to the sensor block 110 transmitted to the sensor block 110 to supply power required for the operation of the sensor block and a display block providing an interface with the host terminal.

The physical structure of the sensor block 110 includes an upper electrode and a lower electrode, and an elastic body coupled between the upper electrode and the lower electrode, similar to a force touch (FT) sensor, in a capacitive type. Pressure (force) can be measured.

The sensor block 110 is configured such that the sensor cells 1111 divided into a plurality of pieces form the sensor unit 111, and the same number of sensor cells are disposed on the left and right respectively for uniform setting of the left and right pressure balance of the artificial joint. It may be configured to include a first sensor unit 111a on the left and a second sensor unit 111b on the right.

In this embodiment, the first and second sensor units 111a and 111b each have 9 sensor cells 1111 disposed, but the number and arrangement of the sensor cells included in each sensor unit are the same, It can be set in various ways according to the environment and specifications of the artificial joint.

In addition, the sensor block 110 includes a sensor unit 111 that detects sensor raw data, which is information on the pressure level of the upper and lower positions of the artificial joint, and an MCU 112 that controls transmission of sensing data sensed from the sensor unit to a host. It may include an antenna 113 for wirelessly transmitting the sensing data to a host under the control of the MCU, and a peripheral circuit 114 for performing oscillation and regulator functions.

The MCU 112 checks the state of the battery block 120, controls data transmission/reception through wireless communication with a data calculating means, and when a preprocessing process is performed and a scan command is received, the sensor detected through the sensor unit is used. It plays a role of wirelessly transmitting data to the data calculating means.

3 is a perspective view schematically illustrating an artificial joint equipped with a smart sensor of FIG. 1.

Referring to FIG. 3, the artificial joint 30 includes a base plate 310 on which a sensor is mounted, a spacer 320 disposed on the base plate to adjust the spacing of the sensor unit, and a smart sensor disposed on the spacer ( 10) and a tibia insert 330 disposed on the sensor unit to serve as a tibia, and a femur insert 340 coupled on the tibia insert to serve as a femur.

When the smart sensor 10 is inserted into the knee while being mounted in the artificial joint, sensing is performed through the smart sensor to obtain pressure information necessary for setting the artificial joint for pressure balancing, the smart sensor is removed. , The artificial joint is fixed to the knee according to the artificial joint setting information.

4 is a system configuration diagram schematically showing a smart sensor system for knee artificial joint surgery according to a preferred embodiment of the present invention.

4, the smart sensor system for knee artificial joint surgery according to the present invention is inserted into the artificial joint and from the smart sensor 10 and the smart sensor to detect sensor raw data, which is pressure magnitude information for each upper and lower position of the artificial joint. It may be configured to include a data calculation means 20 for receiving the sensed sensor raw data and calculating pressure information required for artificial joint setting.

Here, the data calculation means 20 may be composed of a host terminal or a cloud server, and based on the sensor raw data transmitted through wireless communication with the smart sensor 10, pressure information required for artificial joint setting is calculated. .

Here, the smart sensor 10 and the data calculating means 20 may transmit and receive data through short-range wireless communication such as Bluetooth, Zigbee, infrared, and RF, but are configured in a Bluetooth method supporting low power Bluetooth (BLE). It is desirable.

The pressure information is information necessary to set the artificial joint in the correct position.It is information for guiding the artificial joint to be installed in the correct position by adjusting the balance of the gap, angle, and pressure between the tibia and femur.The load acting on the sensor cell (Pressure), coordinates, and angle information are included.

The data calculation means 20 manages the smart sensor inserted into the artificial joint, checks the communication state with the smart sensor, and receives and manages the sensor raw data through wireless communication, and the transmitted A pressure information calculation module 220 for calculating pressure information from sensing data, a database 230 for storing and managing equations, parameters, environment information, and calculated pressure information for calculating the pressure information, and outputting the calculated pressure information It may be configured to include the display module 240.

More specifically, when there is FW update information, the sensor management module 210 transmits it to the smart sensor, and when the smart sensor 10 is powered on from the battery, it receives the result of the battery check, and It performs a pre-processing process for scanning, commands a sensor scan through wireless communication with the smart sensor 10, and receives and manages sensor raw data detected through the sensor unit.

Further, the pressure information calculation module 220 performs a pre-processing process for the sensor raw data of each sensor cell received by the sensor management module 210, a force correction, and a matching process with Newton, and the force correction value of each cell It is responsible for calculating the pressure data by calculating the coordinates and angles for.

5 is a flowchart schematically showing a method of calculating pressure information for knee artificial joint surgery using a smart sensor according to a preferred embodiment of the present invention.

Referring to FIG. 5, when power is first applied through a battery block of a smart sensor and is powered on, the MCU of the sensor block performs a preprocessing process.

Here, the preprocessing process may include a system operation initialization operation, a battery check, and an OTA FW update operation.

First, the system operation initialization work is performed.

Here, the system operation initialization operation may include system initialization, boot loader SRAM initialization for OTA FW update, and smart sensor initialization.

The system initialization may include smart sensor information setting (version information/sensor-related information), I2C block initialization, BLE block initialization, WTD block initialization, ADC block initialization, EEPROM block initialization, and the smart sensor initialization is a smart sensor block. This may include initialization, sensor baseline initialization, pressure calibration parameter initialization, and Force matching to Newton parameter initialization.

Next, the battery check of the smart sensor is performed.

6 is a flowchart schematically illustrating a battery check method of a smart sensor according to the present invention.

6, the MCU of the sensor block checks the level of the battery, checks the battery level in% units once every set time (for example, 2.5 seconds), generates report data, and generates a sensor management module through BLE. Transfer to.

Subsequently, the MCU of the sensor block checks whether the FW is upgraded through the received CMD. Here, if there is a received FW upgrade, it is upgraded through BLE and fed back to the power on step.

Here, the FW (firmware) has a function of controlling the basic operation of hardware in priority over other software, and automatically performs an OTA FW update operation when power is applied and there is an FW upgrade through the received CMD.

Next, the MCU scans the sensor unit. That is, scanning of sensors including all sensor cells included in the first and second sensor units is started, and raw sensor data is transmitted to the data calculating means.

Subsequently, a pre-processing process for the sensor raw data of each sensor cell, force correction, and matching with Newton are performed.

First, pre-processing is performed on the raw data of the sensor.

7 is a flowchart schematically illustrating a pre-processing process for raw sensor data according to an exemplary embodiment of the present invention.

Referring to FIG. 7, first, it is checked whether it is a first press or first release, and if it is the first pressure, an adaptive filter is set, and if it is not the first pressure, the adaptive filter setting has already been completed. Forward to the next step.

In this case, the adaptive filter setting dynamically changes other filters, thereby generating an effect of rapidly responding to rapid changes in sensor data.

Subsequently, the raw sensor data is filtered, and sensor variation data for each sensor cell of the sensor unit is calculated.

Consequently, the sensor change data may be defined as data in which raw data for the scanned sensor cell is changed through filtering.

For the filtering, a moving average filter may be applied, and optionally, a low pass filter or a Kalman filter may be applied.

Next, force calibration and force matching to newton are performed.

8A is a flow chart schematically showing a force correction process according to a preferred embodiment of the present invention, and FIG. 8B is a flow chart schematically showing a force matching process with Newtons according to a preferred embodiment of the present invention.

8A and 8B, first, the force correction process checks a current input value for input data (sensor change data for each sensor cell), and if it is less than a boundary load (eg, 50N), the following equation Force correction is performed by 1-1, and when it is greater than the boundary load 50N, force correction is performed according to Equation 1-2 below to calculate output data (corrected sensor change data of each cell).

Equation 1-1: Y= A*(EXP(B*X)-EXP(C*X))

Equation 1-2: Y=(A+X)/(B+C*X**2)+D*X

Here, the boundary load (50N≒5kgf) is divided into a sharp curve section (the first section) and a gentle curve section (the first section) in the graph of FIG. do.

In addition, Equation 1-1 is an equation for straightening the first section, and Equation 1-2 is an equation for straightening the second section.

Here, the A/B/C/D is because the values of each sensor cell of the curve of step 1 and step 2 draw different curves, so that the sensor cells to match the ideal linear value, which is the straightened force (Y) They are constant values, X is the force of each cell currently input, and Y is the force of each cell linearized by the formula.

That is, the force correction is to calculate an equation so that the amount of change in the sensor value according to the applied load becomes linear.Since the sensor unit is composed of a plurality of sensor cells and the change amount curve of each cell is different, the force correction formula must be calculated for each cell. do.

In more detail, the force correction process is first measured by measuring the amount of change according to the applied load for each sensor cell of the sample.

That is, it is applied to the sensor measurement positions for 9 cells of the first sensor unit on the left (LSO, LS1 to LS8) and the sensor measurement positions for 9 cells of the second sensor unit on the right (RS0, RS1 to RS8). The amount of change according to the load (1.5kgf, 3kgf, 5kgf, 7kgf, 10kgf, 15kgf, 20kgf) is measured.

9 schematically shows a change amount curve for each load according to a preferred embodiment of the present invention.

In addition, the average value of the change amount according to the applied load for each cell is calculated according to the number of measurement samples, and the force correction formula for each cell is calculated so that the change amount curve for each load is linearized.

Accordingly, when the force correction formula for all cells is calculated, the formula is verified through data simulation, and an active force value for each corrected cell with ΣFValid of 1.5kgf is calculated.

Here, the minimum motion load in terms of human body structure and mechanics during knee surgery is 1.5kgf, and since 1.5kgf or less is a too weak load, it is meaningless, so the effective force value can be set to 1.5kgf.

Subsequently, when the applied load is less than the boundary load (for example, 50N), force correction is performed according to Equation 1-1, and when it is greater than the boundary load, force correction is performed by Equation 1-2 above. To calculate output data (corrected sensor change data of each cell).

10 schematically illustrates a simulation graph according to a force correction process according to a preferred embodiment of the present invention.

Next, looking at the force matching process in Newton, the output data in the force correction process becomes input data (corrected sensor change data of each cell), and the force of the effective force region is determined by Equation 2-1 below. The sum (ΣFValid) is calculated, and the load (force) for each sensor cell of the sensor unit is calculated by force matching with Newton by the following equation 2-2 as the applied load using the sum of the forces (ΣFValid).

Equation 2-1: ΣFValid = fmax + fmax-1 + fmax-2

Equation 2-2: Y = A+B*X+C*X**2+D*X**3

Here, Equation 2-1 means that the total force applied to all sensors at any one point is obtained as the sum of the three sensor cells, and fmax, fmax-1, and fmax-2 are the total force applied at the time point. It means three sensor cells, and ΣFValid represents the sum of the values of the three sensor cells. Here, it is obvious that the number of sensor cells is not limited to three, but can be changed to three or more sensor cells.

Equation 2-2 is an equation for straightening a slight curve arc phenomenon as shown in FIG. 10 when the ΣFValid is applied. The A/B/C/D: curve arc phenomenon slightly when the ΣFValid is applied It appears again, and the values are constant values to match the linearized value in Newton units, X is ΣFValid in Equation 2-1, Y is the total force straightened by the equation, and at the same time, the unit of the force is substituted from Kgf to Newton. Means one value.

Next, it is checked whether the input force (sum of the corrected force of the effective force region) is greater than the set active force.

Here, the effective force is a force required for the pressure balance of the artificial joint, and when the input force is less than the effective force, the pressure is unbalanced, so it is necessary to track the baseline of the sensor by feedback.

Therefore, when the input force is less than the effective force, the sensor base value is upgraded through baseline tracking and then fed back to the power check step.

And when the input force is greater than the effective force, coordinates and angles are calculated.

11A schematically shows a coordinate calculation process according to a preferred embodiment of the present invention, FIG. 11B schematically shows a coordinate correction process, and FIG. 11C is a flowchart schematically showing an angle calculation process.

Referring to FIG. 11A, first, it is assumed that independent force is applied to the left area (first sensor unit) and the right area (second sensor unit) of the sensor, and input data (uncorrected sensor change data and corrected ΣFValid) For ), it is checked whether ΣFValid in the left area is greater than the effective force, and if it is large, the left X and Y coordinates are calculated by Equation 3-1.

Here, if ΣFValid in the left area is less than the effective force, feedback is performed by setting left X=0, Y=0, and left force=0.

Then, with respect to the input data (uncorrected sensor change data and corrected ΣFValid), it is checked whether ΣFValid in the right area is greater than the effective force, and if larger, the right X and Y coordinates are calculated by Equation 3-1.

And, similar to the left, if ΣFValid in the right area is smaller than the effective force, the right X=0, Y=0, and the right force=0 are set and fed back.

Equation 3-1:

a. LX = Ratio * (LFx / ΣFLeft)

b. LY = Ratio * (LFy / ΣFLeft)

c. RX = Ratio * (RFx / ΣFRight)

d. RY = Ratio * (RFy / ΣFRight)

12 schematically shows the force distribution of the sensor cell of the first sensor unit on the left according to a preferred embodiment of the present invention.

Referring to Figure 12, looking at the coordinate calculation process,

Left force ΣFLeft = f0+ f1+ ... +f8

Force in the x direction LFx = 2.9*(f3+ f7-f1-f5)+ 5.8*f6-2.9(f1+ f5)-5.8*f2

The x-coordinate is (2.9*(f3+ f7- f1- f5)+ 5.8*(f6- f2))/ ΣFLeft* Ratio.

And the force in the y direction is LFy = 5*(f5 + f7)+ 10*f8- 5*(f1 + f3)-10 * f0

The y coordinate is (5*(f5 + f7-f1-f3)+ 10*(f8-f0)) / ΣFLeft* Ratio.

Here, F and fn are force values to which the force correction is not applied, Ratio is a scalar function for increasing the resolution of the coordinates, and an algorithm may be calculated using the same modeling for the right area.

When the left X,Y coordinates and the right X,Y coordinates are calculated as described above, it is checked whether or not a correction parameter exists, and if the correction parameter exists, coordinate correction is performed by Equation 3-2.

Equation 3-2: a. XCal_L = LeftParmX1 * X_Left + LeftParmX2 * Y_Left + LeftParmX3

b. YCal_L = LeftParmY1 * X_Left + LeftParmY2 * Y_Left + LeftParmY3

c. XCal_R = RightParmX1 * X_Left + RightParmX2 * Y_Left + RightParmX3

d. YCal_R = RightParmY1 * X_Left + RightParmY2 * Y_Left + RightParmY3

Here, RightParmX1, RightParmX2, RightParmX3, RightParmY1, RightParmY2 and RightParmY3 are correction parameters.

13 schematically shows an equation of a coordinate correction algorithm according to a preferred embodiment of the present invention.

More specifically, the coordinate correction method can be applied to a coordinate correction algorithm commonly used in touch-screen products, and to apply the coordinate correction algorithm, input coordinates of three or more points not located on the same straight line are required, and input Although the correction effect increases as the number of coordinates increases, the five-point correction algorithm can be applied because the process becomes complicated.

Looking at an example of coordinate correction using a three-point correction algorithm,

Destination Coordinates: P1(64, 384), P2(192, 192), P3(192, 576)

Input Coordinates: p1(678, 2169), P2(2807, 1327), P3(2629, 3367)

Applying Equation (1) in Fig. 12

αX, = 0.0623, βX, = 0.0054, ΔX = 9.9951 and αY, = -0.0163, βY, = 0.1868, ΔY = -10.1458.

So, X = 0.0623 * XI, + 0.0054 * YI + 9.9951

Y = -0.0163 * XI, + 0.1868 * YI + (-10.1458)

For example, if the current input coordinate is (1000, 2000), the corrected coordinate is;

X = 0.0623 * 1000 + 0.0054 * 2000 + 9.9951 = about 83

Y = -0.0163 * 1000 + 0.1868 * 2000 + (-10.1458) = about 347.

And, the minimum and maximum boundaries for the X and Y coordinates are checked through Equation 3-3 below.

Equation 3-3: a. Resolution XMin = -400

b. Resolution XMax = 400

c. Resolution XMin = -650

d. Resolution XMax = 650

Then, the angle between the two coordinates of the left and right regions is calculated.

More specifically, radians are calculated by Equation 3-4 for the left X,Y and right X,Y coordinates.

Equation 3-4: Radian = atan(dY/dX)

And if the left ΣFValid and the right ΣFValid are greater than 0, the angle is calculated by Equation 3-5.

Equation 3-5: Angle = Radian * (180/PI)

14 schematically shows a coordinate system for calculating an angle according to a preferred embodiment of the present invention.

Here, since the left area and the right area are independent coordinate systems, an angle between the two coordinates cannot exist. In addition, as shown in FIG. 10, in order to obtain the angle between the two coordinates, a virtual coordinate system including two coordinate systems at the center of the two coordinate systems and two coordinate systems are defined as being separated by "Distance" from each other.

Here, X Resolution: -400 ~ 400 (same left area/right area)

Y Resolution: -650 ~ 650 (left area/right area same)

Distance: When sensor is set to 1200

tanθ = dY / dX

θ = atan(dY / dX) = Radian

Since it is defined as Angle(Degree) = Radian * (360 / 2π), let's look at an example;

If Left X, Y = (100, -200) Right X, Y = (100, 200) Distance = 1200

dX = Right X-Left X + 2* Distance = 100-100 + 2400 = 2400

dY = Right Y-Left Y = 200-(-200) = 400

Radian = atan(dY / dX) = atan(400 / 2400) = about 0.16514868

Angle(Degree) = Radian * (360 / 2π) = about 9.5°

Through the above process, the load, coordinates, and angle are calculated, and the sensor report data calculated through BLE is transmitted and fed back to the power check step, so that the process of calculating the load, coordinates, and angle may be repeated.

Accordingly, pressure information including load (force), coordinates, and angles of each sensor cell for pressure balancing of artificial joints can be accurately calculated and provided.

10: smart sensor 20: data calculation means

Claims (8)

A smart sensor that is inserted into the artificial joint and senses data by means of a sensor that is information on the pressure level of each upper and lower position of the artificial joint;
And a data calculating means for receiving the sensor raw data sensed from the smart sensor and calculating pressure information necessary for setting an artificial joint;
The smart sensor
A sensor block that checks a battery state, senses the sensor raw data, and transmits the detected sensor raw data to the data calculating means, and a battery block connected to the sensor block to supply power required for the operation of the sensor block. Smart sensor system for knee artificial joint surgery, characterized in that.
The method of claim 1,
The sensor block
It is composed of sensor cells divided into multiple pieces,
A smart sensor system for knee artificial joint surgery, characterized in that it includes a first sensor unit and a second sensor unit in which the same number of sensor cells are arranged on the left and the right, respectively, for uniform setting of the left and right pressure balance of the artificial joint. .
The method of claim 2,
The sensor block
A sensor unit that senses sensor raw data, which is information on the pressure level of each upper and lower position of the artificial joint; An MCU controlling transmission of sensing data sensed from the sensor unit to a host; And an antenna for wirelessly transmitting the sensing data to a host under the control of the MCU;
The MCU is
The state of the battery block is checked, data transmission and reception are controlled through wireless communication with the data calculation means, and when a preprocessing process is performed and a scan command is received, the sensor raw data sensed through the sensor unit is wirelessly transmitted to the data calculation means. Smart sensor system for knee artificial joint surgery, characterized in that to control.
The method of claim 2,
The data calculation means
If there is FW update information for the smart sensor, it transmits it to the smart sensor.When the smart sensor is powered on from the battery, it receives the result of the battery check, performs a preprocessing process for scanning the sensor unit, and performs the smart A sensor management module for commanding a sensor scan through wireless communication with a sensor, and receiving and managing sensor raw data detected through the sensor unit;
Including a pre-processing process for the sensor raw data of each sensor cell received by the sensor management module, performing a force correction and matching process with Newton, and calculating coordinates and angles for the force correction values of each cell. Smart sensor system for knee artificial joint surgery, characterized in that it comprises a pressure information calculation module for calculating the pressure information.
The method of claim 4,
The sensor management module
System initialization including smart sensor information setting (version information/sensor-related information), I2C block initialization, BLE block initialization, WTD block initialization, ADC block initialization, and EEPROM block initialization; Initializing the boot loader SRAM for OTA FW update; System operation initialization including smart sensor initialization including smart sensor block initialization, sensor baseline initialization, pressure calibration parameter initialization, force matching to Newton parameter initialization, battery check, OTA FW update operation Performing a pretreatment process;
When the pre-processing process is finished, the smart sensor system for knee artificial joint surgery, characterized in that transmitting a scan command to the smart sensor.
The method of claim 3,
The pressure information calculation module
Performing the pre-processing process, force correction, and force matching process with Newton;
The pre-processing process checks whether the sensor raw data is first press or first release, sets an adaptive filter, filters the raw sensor data, and filters each sensor cell of the sensor unit. Calculating sensor variation data for;
The force correction process
The formula is calculated so that the amount of change in the sensor value according to the applied load becomes linear, but since the sensor unit is composed of a plurality of sensor cells and the change curve of each cell is different, the force correction formula is used to calculate the input data (each sensor cell The current input value for (sensor change data for) is checked, and if it is less than the boundary load, force correction is performed according to Equation 1-1 below, and if it is greater than the boundary load, force according to Equation 1-2 below. Performing correction to calculate output data (corrected sensor change data of each cell);
Equation 1-1: Y= A*(EXP(B*X)-EXP(C*X))
Equation 1-2: Y=(A+X)/(B+C*X**2)+D*X
The force matching process is
The output data in the force correction process becomes input data (corrected sensor change data of each cell), and the sum of the forces in the effective force region (ΣFValid) is calculated by Equation 2-1 below, and the sum of the forces Knee artificial, characterized in that it comprises the step of calculating the load (force) for each sensor cell of the sensor unit by matching the force with Newton by Equation 2-2 below as an applied load (ΣFValid) Smart sensor system for joint surgery.
Equation 2-1: ΣFValid = fmax + fmax-1 + fmax-2
Equation 2-2: Y = A+B*X+C*X**2+D*X**3
The method of claim 3,
The pressure information calculation module
The process of calculating the coordinates for the force correction value of each cell is
Assuming that independent forces are applied to the left area (first sensor unit) and the right area (second sensor unit) of the sensor, ΣFValid in the left area for input data (uncorrected sensor change data and corrected ΣFValid) It is checked whether it is greater than the effective force, and if it is greater, left X and Y coordinates are calculated by Equation 3-1;
For input data (uncorrected sensor change data and corrected ΣFValid), it is checked whether or not ΣFValid in the right area is greater than the effective force, and if larger, right X,Y coordinates are calculated by Equation 3-1;
Equation 3-1:
a. LX = Ratio * (LFx / ΣFLeft)
b. LY = Ratio * (LFy / ΣFLeft)
c. RX = Ratio * (RFx / ΣFRight)
d. RY = Ratio * (RFy / ΣFRight)
Calculating the angle between the two coordinates of the left and right areas; Radians are calculated by Equation 3-4 for the calculated left X,Y and right X,Y coordinates;
Equation 3-4: Radian = atan(dY/dX)
If the left ΣFValid and the right ΣFValid are greater than 0, the angle is calculated by Equation 3-5.
Equation 3-5: Angle = Radian * (180/PI)
The method of claim 7,
The pressure information calculation module
When the left X,Y coordinates and the right X,Y coordinates are calculated, it is determined whether or not a correction parameter exists, and if the correction parameter exists, performing coordinate correction by Equation 3-2 to calculate the coordinates. Smart sensor system for knee artificial joint surgery, characterized in that.
Equation 3-2: a. XCal_L = LeftParmX1 * X_Left + LeftParmX2 * Y_Left + LeftParmX3
b. YCal_L = LeftParmY1 * X_Left + LeftParmY2 * Y_Left + LeftParmY3
c. XCal_R = RightParmX1 * X_Left + RightParmX2 * Y_Left + RightParmX3
d. YCal_R = RightParmY1 * X_Left + RightParmY2 * Y_Left + RightParmY3
Here, RightParmX1, RightParmX2, RightParmX3, RightParmY1, RightParmY2 and RightParmY3 are correction parameters.

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