Patent ID: 12235136

DESCRIPTION OF THE EMBODIMENTS

FIGS.1A to1Care schematic diagrams of a system1according to an embodiment of the disclosure. Referring toFIGS.1A to1C, the system1includes (but is not limited to) a magnetic field emitter10, a magnetic field sensor50, and a controller70.

In an embodiment, the system1may be configured for electromagnetic field positioning. For example, (S1) a virtual space model of the magnetic field emitter10is established according to an origin and a turning point of a line segment; (S2) a current is fed in and magnetic sensing intensity at any point in space is measured to correlate magnetic field intensity with a spatial position; (S3) the magnetic field sensor50is introduced to establish a correlation between the magnetic field intensity and voltage (magnetic flux) change; (S4) transmitting coil magnetic field models of (S1) and (S2) are optimized; (S5) a position and a direction of the magnetic field sensor50are calculated (as shown inFIG.1A) through experiments and model magnetic flux least square errors; (S6) a visualized three-dimensional environment is established according to coordinate information. In this way, the position and the posture of the magnetic field sensor50may be estimated based on the magnetic flux measured by the magnetic field sensor50(as shown inFIGS.1B and1C).

TakingFIG.1Cas an example, the magnetic field sensor50may be disposed on an organ of a person P, and a computer or other controllers may control radiation of the magnetic field emitter10, measure the magnetic flux through the magnetic field sensor50, and obtain the position and/or the posture of the organ accordingly.

It should be noted that there are many ways to realize electromagnetic field positioning, which are not limited by the embodiment of the disclosure. In addition, the system1may further have other application scenarios.

In an embodiment, the magnetic field emitter10includes multiple transmitting units11.

For example,FIG.2is a schematic diagram of a magnetic field emitter10B and the magnetic field sensor50according to an embodiment of the disclosure. Referring toFIG.2, the magnetic field emitter10B includes multiple transmitting units Tx1, Tx2, Tx3, Tx4, Tx5, Tx6, Tx7, and Tx8. Each of the transmitting units Tx1, Tx2, Tx3, Tx4, Tx5, Tx6, Tx7, and Tx8includes one or more planar transmitting coils. The planar transmitting coil in each of the transmitting units Tx1, Tx2, Tx3, Tx4, Tx5, Tx6, Tx7, and Tx8is a helical coil formed according to a quadrilateral (but may also be a triangle, a hexagon or other polygons) surround made of wires (for example, made of copper, aluminum or other conductive materials) on a plane (for example, a horizontal plane, a vertical plane or any plane). The planar coil facilitates the realization of thinner and higher density design.

In an embodiment, each of the transmitting units Tx1, Tx2, Tx3, Tx4, Tx5, Tx6, Tx7, and Tx8is disposed on a substrate by a stacking process. For example, the stacking process technology includes a printed circuit board (PCB), a flexible printed circuit (FPC), or low-temperature co-fired ceramic (LTCC).

The transmitting units Tx1, Tx3, Tx6, and Tx8surround the transmitting units Tx2, Tx4, Tx5, and Tx7. Respective distances from the transmitting units Tx1, Tx3, Tx6, and Tx8to a central point of the magnetic field emitter10B are greater than the respective distances from the transmitting units Tx2, Tx4, Tx5, and Tx7to the central point of the magnetic field emitter10B. The transmitting units Tx1, Tx3, Tx6, and Tx8are rotated by 45 degrees compared to the transmitting units Tx2, Tx4, Tx5, and Tx7.

It should be noted that there may be other variations in the number and arrangement of the transmitting units, and the transmitting units are not limited to the planar transmitting coils.

In an embodiment, each of the transmitting units Tx1to Tx8independently inputs a current (for example, an alternating current). The electrical characteristics of the transmitting units Tx1to Tx8are the same. The electrical characteristics are the voltage gains of the magnetic field emitter10and the magnetic field emitter10B or the current gains of the magnetic field emitter and the magnetic field emitter10B. For example, the voltage gains, the current gains and/or the current frequency of the transmitting units Tx1to Tx8may be the same. The electrical characteristics of the transmitting units Tx1, Tx3, Tx6, and Tx8may be one to two times the electrical characteristics of the transmitting units Tx2, Tx4, Tx5, and Tx7. For example, the voltage gains and/or the current gains of the transmitting units Tx1, Tx3, Tx6, and Tx8are one to two times of the voltage gains and/or the current gains of the transmitting units Tx2, Tx4, Tx5, and Tx7. For another example, the current frequency of the transmitting units Tx1to Tx8is different. The current frequency may be between 3 and 100 kilohertz (kHz). Thus, a composite uniform magnetic field may be generated.

The magnetic field sensor50includes a sensing unit (for example, one or more planar or columnar sensing coils). Taking the planar sensing coil as an example, the planar sensing coil is a helical coil formed according to a geometry surround made of wires (for example, made of copper, aluminum or other conductive materials) on a plane (for example, a horizontal plane, a vertical plane or any plane). In some embodiments, the geometry is a polygon (for example, a quadrilateral, a hexagon, or an octagon) or a circle.

In an embodiment, the sensing unit of the magnetic field sensor50is disposed on a flexible substrate by a stacking process. For example, the stacking process method includes a PCB, an FPC, or LTCC. The flexible substrate is, for example, a polyimide (PI) film or made of a biocompatible polymer material, which is adapted to stick on the surface of the body or stick to internal organs. In an embodiment, the wire is embedded with a ferrite core. The ferrite core has a feature of high magnetic permeability and may optimize the sensing voltage output, thereby increasing the system signal-to-noise ratio and reducing the position and direction errors.

It should be noted that the sensing unit is not limited to the planar or columnar sensing coil.

FIG.3is a block diagram of elements of the controller70according to an embodiment of the disclosure. Referring toFIG.3, the controller70includes (but is not limited to) a communication transceiver71, a memory72, and a processor73.

The communication transceiver71includes (but is not limited to) an amplifier, an analog-to-digital converter, a filter, an oscillator, and/or a data acquisition interface card. In an embodiment, one or more communication transceivers71are connected to the magnetic field emitter10and the magnetic field sensor50. The communication transceiver71may receive the sensing value (i.e., the intensity of the sensing signal) from the magnetic field sensor50. In addition, the communication transceiver71may transmit a control command to the magnetic field emitter10and the magnetic field sensor50. The control command is, for example, to adjust the electrical characteristics of the magnetic field emitter10and the magnetic field sensor50. The electrical characteristic is, for example, the voltage gain of the magnetic field emitter10, the current gain of the magnetic field emitter10or the voltage gain of the magnetic field sensor50.

The memory72may be any type of fixed or removable random access memory (RAM), read only memory (ROM), flash memory, conventional hard disk drive (HDD), solid-state drive (SSD) or similar elements. In an embodiment, the memory72is configured to store program codes, software modules, configurations, data or files (for example, magnetic field numerical models, sensing values or parameters), which is to be described in detail in subsequent embodiments.

The processor73is coupled to the communication transceiver71and the memory72. The processor73may be a central processing unit (CPU), a graphic processing unit (GPU), or other programmable general purpose or special purpose microprocessors, a digital signal processor (DSP), a programmable controller, a field programmable gate array (FPGA), an application-specific integrated circuit (ASIC), a neural network accelerator or other similar elements or combinations of the above elements. In an embodiment, the processor73is configured to execute all or a part of the operations of the controller70, and may load and execute various program codes, software modules, files, and data stored in the memory72. In some embodiments, some operations in the method of the embodiment of the disclosure may be implemented by different or the same processor73.

Hereinafter, the method described in the embodiment of the disclosure is to be described with various devices, elements, and modules in the system1. Each process of the method may be adjusted accordingly according to the implementation situation, and is not limited thereto.

It is worth noting thatFIGS.4A to4Care schematic diagrams of magnetic field intensity at different sensing positions at a fixed current gain. Please refer toFIGS.4A to4C, which simulate the magnetic field intensity when the magnetic field sensor50is located at 1 centimeter (cm) (i.e., 10 millimeters (mm)), 5 cm (i.e., 50 mm), and 11 cm (i.e., 110 mm) above the magnetic field emitter10, respectively, and the current is 0.25 ampere (A). When the distance between the magnetic field sensor50and the magnetic field emitter10is 10 mm to 50 mm, the amplitude of the magnetic field is not uniform (i.e., the amplitude varies greatly), and the signal-to-noise ratio (SNR) corresponding to sensing at certain positions is particularly small, resulting in positioning errors. Compared with the distance between 10 mm to 50 mm, when the distance between the magnetic field sensor50and the magnetic field emitter10is 110 mm, the amplitude of the magnetic field is more uniformly distributed, which may provide more precise positioning. In light of the above, if the current gain cannot be properly adjusted, the relative position of the magnetic field sensor50and the magnetic field emitter10may greatly affect the positioning effect. When the current gain is increased, such a situation may further cause the effect that the uniform magnetic field moves away from the magnetic field emitter10, resulting in poorer positioning accuracy close to the magnetic field emitter10. In addition, it is known through simulations or experiments that the farther the distance between the magnetic field sensor50and the magnetic field emitter10leads to the gradual decrease in the magnetic field change, resulting in the change in the magnetic field gradient (for example, magnetic field components Bx, By, and Bz) slowing down, the fringe magnetic field intensity of the magnetic field emitter10being relatively weak, and the SNR of the magnetic field signal received by the magnetic field sensor50being directly affected. Therefore, discerning small magnitude position change in the magnetic field sensor50may be difficult. In addition, due to the low SNR and the slowing of the magnetic field gradient, deducing the precise position by measuring change in the magnetic flux of smaller magnitudes is more difficult. In light of the above, improving the existing control mechanism of electromagnetic tracking is necessary.

FIG.5is a flowchart of a control method according to an embodiment of the disclosure. Referring toFIG.5, the processor73determines a working position according to the sensing value obtained by the communication transceiver71from the magnetic field sensor50(step S510). Specifically, the working position is the position of the magnetic field sensor50relative to the magnetic field emitter10. An example is the distance between the magnetic field sensor50and the magnetic field emitter10. Another example is the height of the magnetic field sensor50when the magnetic field emitter10is located on a reference plane.

The processor73may first control the magnetic field emitter10to provide an estimated current gain. The magnetic field sensor50measures the magnetic flux (i.e., the sensing value). The processor73may perform a spatial positioning calculation according to the magnetic flux. In an embodiment, the spatial positioning algorithm is, for example, the Biot-Savart law, in which the magnetic field is related to the magnitude, the direction, and the distance of the current. The Biot-Savart law may analyze magnetic flux density (B) of any current-carrying line segment (I) in the magnetic field emitter10at any point in space, and the magnetic field distribution at the plane height may be drawn accordingly. The processor73may deduce the working position of the magnetic field sensor50according to the magnetic flux (i.e., the sensing value).

In an embodiment, a number of measurement locations may be planned in advance, and the measurement values (for example, the magnetic flux) may be obtained at these measurement locations through the magnetic field sensor50, thereby generating a corresponding relationship between the magnetic flux and the position and the posture or a mathematical model related to the magnetic field value. The memory72may pre-store the corresponding relationship or the mathematical model between the magnetic flux and the position and the posture. The processor73may load the relationship or the mathematical model, and estimate the position and the posture corresponding to the magnetic field sensor50according to the sensing value of the magnetic field sensor50. The position is, for example, a coordinate of a three-dimensional coordinate system. The posture may be an included angle with a horizontal reference plane and a vertical reference plane.

The processor73adjusts the electrical characteristic of the magnetic field emitter10or the magnetic field sensor50to the target characteristic corresponding to the working position (step S520). Specifically, different working positions may provide different electrical characteristics. The electrical characteristic is, for example, the voltage gain of the magnetic field emitter10, the current gain of the magnetic field emitter10, the current frequency of the magnetic field emitter10or the voltage gain of the magnetic field sensor50. One of the purposes of changing the electrical characteristic is to maintain the magnetic field intensity of the space between the magnetic field emitter10and the magnetic field sensor50, and maintain the signal-to-noise ratio corresponding to the sensing signal of the magnetic field sensor50accordingly. For example, the difference in the signal-to-noise ratio is smaller than the corresponding threshold value.

In an embodiment, the magnetic field intensity of the space between the magnetic field emitter10and the magnetic field sensor50may be in the range of 0.5 to 10 amperes per meter (A/m) in response to the operation of the target characteristic by the magnetic field emitter10or the magnetic field sensor50. That is, the processor73controls the magnetic field emitter10or the magnetic field sensor50to operate according to the target characteristic. In addition, the magnetic field intensity at any position in the space between the magnetic field emitter10and the magnetic field sensor50may be between 0.5 to 10 A/m or greater than 5 A/m. In this way, the sensing signal of the magnetic field sensor50has a higher signal-to-noise ratio and a gentler gradient change, thereby ensuring subsequent positioning can be accurate.

In an embodiment, in response to the farther the magnetic field sensor50from the magnetic field emitter10(for example, the larger the distance), the stronger the intensity of the target characteristic. In response to the closer the magnetic field sensor50to the magnetic field emitter10(for example, the smaller the distance), the smaller the intensity of the target characteristic.

In an embodiment, the magnetic field emitter10provides multiple power modes. The power modes are different voltage gains and/or current gains. For example, the peak-to-peak current amplitudes of four power modes are 68 milliamps (mA), 125 mA, 225 mA, and 550 mA, respectively. The processor73may select a first power mode among the power modes according to the working position, and the first power mode meets the corresponding target characteristic. That is, the electrical characteristic corresponding to the first power mode meets (is the same or close to) the target characteristic. The processor73may set the electrical characteristic of the magnetic field emitter10according to the first power mode.

It is assumed that the magnetic field emitter10B ofFIG.2is used, in an embodiment, the working position is that the distance between the magnetic field sensor50and the magnetic field emitter10is less than 15 cm, the peak-to-peak current amplitude of the magnetic field emitter10is 68 mA, and the magnetic field intensity of the space between the magnetic field emitter10and the magnetic field sensor50is about 0.8 A/m.

In an embodiment, the working position is that the distance between the magnetic field sensor50and the magnetic field emitter10is between 15 and 20 cm, the peak-to-peak current amplitude of the magnetic field emitter10is 125 mA, and the magnetic field intensity of the space between the magnetic field emitter10and the magnetic field sensor50is about 0.9 A/m.

In an embodiment, the working position is that the distance between the magnetic field sensor50and the magnetic field emitter10is between 20 and 25 cm, the peak-to-peak current amplitude of the magnetic field emitter10is 225 mA, and the magnetic field intensity of the space between the magnetic field emitter10and the magnetic field sensor50is about 1.05 A/m.

In an embodiment, the working position is that the distance between the magnetic field sensor50and the magnetic field emitter10is greater than 25 cm, the peak-to-peak current amplitude of the magnetic field emitter10is 550 mA, and the magnetic field intensity of the space between the magnetic field emitter10and the magnetic field sensor50is about 1.7 A/m.

In other embodiments, due to different magnetic field emitters10or different magnetic field sensors50, the working positions, the electrical characteristics, and the values of magnetic field intensity may further change.

In an embodiment, if the magnetic field emitter10includes multiple transmitting units11(as shown inFIG.2), the electrical characteristics of the transmitting units11may be the same. For example, when the distance between the magnetic field sensor50and the magnetic field emitter10is greater than 25 cm, the peak-to-peak current amplitude of all the transmitting units11is 550 mA, that is, constant current synchronous driving.

In another embodiment, the magnetic field emitter10includes multiple first transmitting units and multiple second transmitting units, the first transmitting units surround the second transmitting units, and the electrical characteristics of the first transmitting units are one to two times the electrical characteristics of the second transmitting units. That is to say, the intensity of the electrical characteristic of the first transmitting unit located in the outer circle may be the same as or greater than the intensity of the electrical characteristic of the second transmitting unit located in the inner circle. TakingFIG.2as an example, the voltage gains of the transmitting units Tx1, Tx3, Tx6, and Tx8(i.e., the first transmitting units) may be one to two times the voltage gains of the transmitting units Tx2, Tx4, Tx5, and Tx7(i.e., the second transmitting units), that is, non-constant current synchronous driving. In this way, the problem that the change in the magnetic field gradient decreases rapidly with height may be improved.

FIGS.6A to6Dare schematic diagrams of magnetic field intensity at different sensing positions at an adjustable current gain. Referring toFIG.6A, the distance between the magnetic field sensor50and the magnetic field emitter10is less than 15 cm, and the peak-to-peak current amplitude of the magnetic field emitter10is 68 mA. The magnetic field intensity is about 0.4 to 0.8 A/m, and the distribution is roughly uniform (for example, the difference in signal-to-noise ratio is smaller).

Referring toFIG.6B, the distance between the magnetic field sensor50and the magnetic field emitter10is between 15 and 20 cm, and the peak-to-peak current amplitude of the magnetic field emitter10is 125 mA. The magnetic field intensity is about 0.5 to 0.9 A/m, and the distribution is roughly uniform.

Referring toFIG.6C, the distance between the magnetic field sensor50and the magnetic field emitter10is between 20 and 25 cm, and the peak-to-peak current amplitude of the magnetic field emitter10is 225 mA. The magnetic field intensity is about 0.6 to 1.05 A/m, and the distribution is roughly uniform.

Referring toFIG.6D, the distance between the magnetic field sensor50and the magnetic field emitter10is greater than 25 cm, and the peak-to-peak current amplitude of the magnetic field emitter10is 550 mA. The magnetic field intensity is about 1 to 1.7 A/m, and the distribution is roughly uniform.

In an embodiment, when the magnetic field sensor50is close to the magnetic field emitter10, the processor73may reduce the voltage gain of the magnetic field sensor50to prevent the sensing signal from being saturated and causing distortion. When the magnetic field sensor50is far away from the magnetic field emitter10, the processor73may further increase the voltage gain of the magnetic field sensor50to maintain the signal-to-noise ratio of the sensing signal.

In an embodiment, the processor73may simultaneously adjust the electrical characteristics of the magnetic field emitter10and the magnetic field sensor50according to the working position. For example, when the magnetic field sensor50is close to the magnetic field emitter10, the processor73may reduce the voltage gains of both the magnetic field emitter10and the magnetic field sensor50. For another example, when the magnetic field sensor50is far away from the magnetic field emitter10, the processor73may increase the voltage gains of both the magnetic field emitter10and the magnetic field sensor50.

In an embodiment, the processor73may select a corresponding magnetic field numerical model according to the target characteristic. The magnetic field numerical model records the corresponding relationship between the position in space and the magnetic flux/magnetic field intensity. Therefore, in subsequent position estimation, the processor73may determine the position and/or the posture of an object through the selected magnetic field numerical model.

In summary, in the control method and the controller related to electromagnetic tracking in the embodiments of the disclosure, the working position of the magnetic field sensor may be determined, and the electrical characteristics of the magnetic field emitter and/or the magnetic field sensor may be adjusted accordingly (for example, the current or voltage gains). Therefore, when the magnetic field sensor is close to the magnetic field emitter, the sensing signal is not saturated; when the magnetic field sensor is far away from the magnetic field emitter, the magnetic field gradient is still maintained. Even if the magnetic field sensor is at different positions, the signal-to-noise ratio of the sensing signal may still be improved, and the magnetic field gradient may be maintained, thereby improving the positioning accuracy within the working range and improving the user's operating space.

Although the disclosure has been described with reference to the above embodiments, the described embodiments are not intended to limit the disclosure. People of ordinary skill in the art may make some changes and modifications without departing from the spirit and the scope of the disclosure. Thus, the scope of the disclosure shall be subject to those defined by the attached claims.