Target position and speed detection method and system based on coil impedance change

Abstract

The present invention discloses a method and system for detecting the position and speed of a target object based on coil impedance changes, which belongs to the field of magnetic coupling detection technology. At least two detection coils are arranged at predetermined positions along a preset motion trajectory of the target object in conjunction with an impedance conversion detection circuit. The impedance conversion detection circuit records the time when the impedance change of at least two detection coils caused by the target object approaching the detection coil reaches a preset threshold, so that the position and speed of the target object can be determined. The method and system are applied to the charging system of an underwater robot, and can detect the position and speed of the underwater robot during charging, so that the underwater robot can make timely adjustments, so that the underwater robot is in a facing state and enters the charging device at a safe speed, ensuring safe and stable charging. At the same time, the detection coil has a simple structure, a small size, strong stability, low production cost, and is less affected by the environment during detection, which is conducive to implementation and promotion.

Description

Technical Field

[0001] The present invention belongs to the technical field of magnetic coupling detection, and more specifically, relates to a method and system for detecting the position and speed of a target object based on changes in coil impedance. Background Art

[0002] Many application scenarios require detecting the position and velocity of a target object. Underwater robots, for example, are increasingly prominent in scientific experiments, marine surveys, and commercial applications, enabling them to perform a variety of complex underwater tasks. Therefore, charging underwater robots for sustainable operation is crucial. Using wireless power transmission technology to charge underwater robots overcomes the drawbacks of traditional plug-in charging. However, prior to charging, the underwater robot must enter a "bucket-style" charging station. This requires detecting the robot's position and velocity upon entry to ensure safe, stable, and accurate arrival at the charging station and stationary charging.

[0003] Currently, the main technologies for detecting the position and velocity of underwater robots include acoustic detection, visual detection, satellite positioning, inertial navigation, and geo-matching positioning. Acoustic detection is not accurate enough at very close ranges and requires calibration of a complex network of acoustic beacons. In deep-sea environments, the light is too dim, causing blurred vision and failing to meet the required visual detection accuracy. Similarly, satellite positioning and geo-matching positioning are incapable of detecting the position and velocity of underwater robots over short distances and within a small area in deep-sea environments. Inertial navigation is expensive, bulky, and requires high energy. Furthermore, the internal gyroscopes and accelerometers have inherent drift errors, which can lead to inaccurate detection. Summary of the Invention

[0004] In response to the shortcomings of the existing technology, the present invention provides a method and system for detecting the position and speed of a target object based on changes in coil impedance. By setting up at least two detection coils, the eddy current effect generated when there is a metal object around the detection coils is used to change the coil impedance, thereby detecting the position and speed of the target object to solve the technical problems in the background technology.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: A method for detecting the position and speed of a target object based on the change of coil impedance, the key of which is to include the following steps:

[0006] S1: At least two detection coils are arranged at predetermined positions along a preset motion trajectory of the target object, and each detection coil is connected to an impedance change detection circuit;

[0007] S2: recording, by the impedance conversion detection circuit, the time when the impedance change of at least two detection coils caused by the target object approaching the detection coils reaches a preset threshold;

[0008] S3: Determine the position and speed of the target object based on the predetermined positions of the at least two detection coils in step S1 and the time when the impedance change obtained in step S2 reaches a preset threshold.

[0009] As a preferred technical solution of the present invention, in step S1 , a first detection coil and a second detection coil are provided. The first detection coil and the second detection coil are provided relative to each other at a predetermined distance s.

[0010] As a preferred technical solution of the present invention, the first detection coil and the second detection coil are both hollow annular structures, the movement trajectory of the target object is set along the central axis of the first detection coil and the second detection coil, and moves in the annular hollow area of ​​the first detection coil and the second detection coil.

[0011] As a preferred technical solution of the present invention, the first detection coil and the second detection coil are both wound with Litz wire.

[0012] As a preferred technical solution of the present invention, the impedance change detection circuit includes a high-frequency AC signal loading circuit and a voltage detection circuit, and the voltage detection circuit is used to determine the time when the impedance change caused by the target object approaching the detection coil reaches a preset threshold.

[0013] As a preferred technical solution of the present invention, the voltage detection circuit includes a voltage amplitude detection circuit and a voltage phase detection circuit.

[0014] As a preferred technical solution of the present invention, the target object is an underwater robot.

[0015] As a preferred technical solution of the present invention, in step S2, the impedance transformation detection circuit also records the impedance change of at least two detection coils caused by the target object approaching the detection coil, and determines the offset of the target object from the preset motion trajectory based on the impedance change.

[0016] In order to facilitate the implementation of the target position and speed detection method based on coil impedance changes, the present invention also provides a target position and speed detection system based on coil impedance changes, the key of which is that it includes at least two detection coils arranged at predetermined positions along the preset motion trajectory of the target and an impedance change detection circuit respectively connected to each detection coil.

[0017] As a preferred technical solution of the present invention, the target object is an underwater robot, at least two detection coils are arranged near the charging device of the underwater robot, and a target object posture adjustment control module is also arranged between the target object and the impedance change detection circuit.

[0018] The present invention provides a method and system for detecting the position and speed of a target object based on changes in coil impedance, which has the following beneficial effects:

[0019] 1. At least two detection coils are set at predetermined positions along the preset motion trajectory of the target object in conjunction with an impedance conversion detection circuit. The impedance conversion detection circuit records the time when the impedance change of at least two detection coils caused by the target object approaching the detection coils reaches a preset threshold, so that the position and speed of the target object can be detected, which can be used in various scenarios.

[0020] 2. The present invention is applied to the charging device of an underwater robot, which can detect the position and speed of the underwater robot during charging, so that the underwater robot can make adjustments, so that the underwater robot can face the charging device at a safe speed, ensuring safe and stable charging.

[0021] 3. The detection is performed based on the principle that the presence of metal around the detection coil will produce eddy current effect, thereby changing the coil impedance. It is not affected by light, sound, or underwater external environment and has the advantage of strong adaptability.

[0022] 4. The detection coil has a simple structure, small size, strong stability and low production cost, which is conducive to implementation and promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic diagram of the structure of the target position and speed detection system based on coil impedance change provided in this embodiment;

[0024] Figure 2 Equivalent circuit diagram of the target object in the magnetic field provided in this embodiment;

[0025] Figure 3 This is a graph showing the change in the real part of the impedance when the underwater robot with a diameter of 80 cm provided in this embodiment passes through the detection coil;

[0026] Figure 4 This is a graph showing the change in the real part of the impedance when the underwater robot with a diameter of 54 cm provided in this embodiment passes through the detection coil;

[0027] Figure 5 This is a graph showing the change in the real part of impedance for different diameters of the underwater robot provided in this embodiment;

[0028] Figure 6 A schematic diagram of the underwater robot in a position offset state provided in this embodiment;

[0029] Figure 7 Impedance variation diagram of the underwater robot position offset provided in this embodiment;

[0030] Figure 8This is a diagram showing the change in coil impedance after the underwater robot provided in this embodiment faces and deviates;

[0031] Figure 9 This is a flow chart of the underwater robot position and speed detection provided in this embodiment.

[0032] In the figure: 11, first coil; 12, first coil; 2, target object. DETAILED DESCRIPTION

[0033] The following embodiments of the present invention are described in further detail with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0034] In the description of the present invention, unless otherwise specified, "plurality" means two or more; terms such as "upper," "lower," "left," "right," "inner," "outer," "front end," "rear end," "head," and "tail" indicate positions or relationships based on those shown in the accompanying drawings. These terms are intended solely to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limiting the present invention. Furthermore, terms such as "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0035] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "connected" and "connection" should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integral connection; mechanical connection, electrical connection; direct connection, or indirect connection through an intermediary. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0036] refer to Figure 1 As shown, the present invention provides a technical solution: a target position and speed detection system based on coil impedance change, comprising at least two detection coils arranged at predetermined positions along a preset motion trajectory of a target object 2 and an impedance change detection circuit respectively connected to each detection coil; the target object here can be any moving object with metallic properties. This embodiment takes an underwater robot charging system as an example. When this method is applied to the underwater robot charging system, the target object 2 is an underwater robot. For objects such as underwater robots, which contain a large amount of metal, the effect on the coils is very obvious. At least two detection coils can be arranged near the wireless charging base station of the underwater robot, and a target object 2 posture adjustment control module is further provided between the target object 2 and the impedance change detection circuit;

[0037] like Figure 1 and Figure 2 As shown in FIG, when the target 2 enters the alternating magnetic field, due to the influence of the eddy current effect, the target 2 can be equivalent to a circuit of inductance and resistance in series, thereby coupling with the detection coil. When the target 2 does not exist, Figure 2 It can be seen that the impedance of the detection coil is:

[0038] Z0=R s +jωL s

[0039] According to Kirchhoff's law, when metal appears near a energized coil, a voltage balance equation can be obtained:

[0040]

[0041] Therefore, when target 2 exists, the equivalent impedance of the detection coil is:

[0042]

[0043] Similarly, since seawater contains a lot of salt, with a salinity between 3.2% and 3.8%, a conductivity of 4.45-4.81s / m, and a relative dielectric constant of 81, when the detection coil is passed through a high-frequency electromagnetic field, the seawater environment will also produce eddy current effects based on the same principle.

[0044] Therefore, in a seawater environment, due to the different effects of seawater and metal on the coil at different locations, the equivalent impedance of the detection coil when the target 2 exists is:

[0045]

[0046] Furthermore, when the target object 2 is located at different positions of the detection coil, the equivalent impedance of the detection coil will be different.

[0047] According to the above principles, the position and speed of the underwater robot can be detected by detecting the change in the coil impedance. The specific process is as follows: Figure 9 shown.

[0048] This embodiment provides a method for detecting the position and speed of a target object based on coil impedance changes, specifically comprising the following steps:

[0049] S1: At least two detection coils are arranged at predetermined positions along a preset motion trajectory of the target object 2, and each detection coil is connected to an impedance change detection circuit;

[0050] S2: Recording, by means of an impedance conversion detection circuit, the time at which the impedance change of at least two detection coils due to the object 2 approaching the detection coils reaches a preset threshold;

[0051] S3: determining the position and speed of the target object 2 according to the predetermined positions of the at least two detection coils in step S1 and the time when the impedance change obtained in step S2 reaches a preset threshold;

[0052] In step S1, a first detection coil 11 and a second detection coil 12 are provided, and the first detection coil 11 and the second detection coil 12 are provided relative to each other at a predetermined distance s.

[0053] The first detection coil 11 and the second detection coil 12 are both hollow annular structures. The motion trajectory of the target 2 is set along the central axis of the first detection coil 11 and the second detection coil 12, and the target 2 moves in the annular hollow area of ​​the first detection coil 11 and the second detection coil 12;

[0054] Wherein, the first detection coil 11 and the second detection coil 12 are both wound with Litz wire;

[0055] The impedance change detection circuit includes a high-frequency AC signal loading circuit and a voltage detection circuit, and is typically further configured with a power supply circuit, an amplification circuit, a filtering circuit, and a control circuit. The high-frequency AC signal loading circuit primarily loads a high-frequency AC signal source onto each detection coil, and uses the voltage detection circuit to determine when the impedance change caused by the target object 2 approaching the detection coil reaches a preset threshold. Specifically, the voltage detection circuit includes a voltage amplitude detection circuit and a voltage phase detection circuit. The impedance change of the detection coil can be reflected by detecting the voltage amplitude and phase.

[0056] In step S2, the impedance change of at least two detection coils caused by the target object 2 approaching the detection coils is recorded by the impedance transformation detection circuit, and the offset of the target object 2 from the preset motion trajectory is determined according to the impedance change.

[0057] For intuitive understanding, a more vivid explanation is given through simulation experiments:

[0058] The simulation is conducted using an 80cm diameter underwater robot (10mm aluminum alloy shell), a 1m diameter, and a 4MHz frequency detection coil. The simulation process only considers the impact of the metal and seawater environment on the detection coil. The coil is wound with 5 turns of 2mm Litz wire, with a spacing of 10mm between the coils. Figure 3The experimental results shown show that the underwater robot passes through the first coil 11 at a distance of 20 mm and the second coil 12 at a distance of 30 mm. The simulation results show that the coil impedance varies significantly when the underwater robot is in different positions. The impedance of the detection coil is represented by a voltage signal, and impedance changes are reflected by voltage changes. Therefore, the position of the UUV can be determined based on the voltage levels of the two detection coils. Since the distance s between the detection coils remains constant, the speed of the UUV at that time, V = s / t, can be calculated based on the time difference t between the detected detection coil voltage changes from 20 mm to 30 mm.

[0059] The 80cm diameter underwater robot is replaced by a 54cm diameter underwater robot for simulation, and the results are as follows: Figure 4 Figure 5 The experimental results shown by Figure 4 It can be seen that the position and speed of the 54cm underwater robot can also be measured by the detection coil. Figure 5 It can be seen that when a 54cm underwater robot passes by, the impedance change of the detection coil is different from that when it is 80cm. Therefore, by using the above system and method to accumulate a large amount of sample data, not only can the position and speed of the underwater robot be detected, but also the model and size of the underwater robot can be known.

[0060] like Figure 6 As shown in the figure, the underwater robot with a diameter of 54cm is offset by a certain distance for simulation. Taking the offset center position of 18cm as an example, the following results are obtained through experiments: Figure 7 Figure 8 The experimental results shown by Figure 7 It can be seen that after the position shifts, the relative position of the underwater robot relative to the coil can also be detected based on the change in impedance, and the speed of the underwater robot can also be obtained. Figure 8 It can be seen that the coil impedance and coil impedance change of the underwater robot are very different when it is facing and offset. Therefore, it is also possible to perform multi-dimensional analysis on the detection data to detect whether the underwater robot is facing the charging device at this time to ensure safe and stable charging.

[0061] This simulation uses the underwater robot's 10mm metal shell and seawater environment for simulation. In reality, the underwater robot contains a large amount of metal objects, and the impedance change will be more obvious.

[0062] It should be noted that the target position and speed detection method and system based on coil impedance change of the present invention can be used not only for charging underwater robots, but also for aircraft in the air and vehicles on land.

[0063] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A method for detecting the position and speed of a target object based on changes in coil impedance, characterized in that: The following steps are involved: S1: at least two detection coils are arranged at predetermined positions along a preset motion trajectory of the target object (2), and each detection coil is connected to an impedance change detection circuit; S2: recording, by the impedance change detection circuit, the time when the impedance change of at least two detection coils reaches a preset threshold value due to the target object (2) approaching the detection coil; S3: determining the position and speed of the target object (2) based on the predetermined positions of the at least two detection coils in step S1 and the time when the impedance change obtained in step S2 reaches a preset threshold; In step S1, a first detection coil (11) and a second detection coil (12) are provided, wherein the first detection coil (11) and the second detection coil (12) are both hollow annular structures, and the movement trajectory of the target object (2) is provided along the central axis of the first detection coil (11) and the second detection coil (12), and moves in the annular hollow area of ​​the first detection coil (11) and the second detection coil (12).

2. The target position and speed detection method based on coil impedance change according to claim 1, characterized in that: The first detection coil (11) and the second detection coil (12) are arranged relative to each other at a predetermined distance s.

3. The target position and speed detection method based on coil impedance change according to claim 2, characterized in that: The first detection coil (11) and the second detection coil (12) are both wound with Litz wire.

4. The method for detecting the position and speed of a target object based on coil impedance change according to any one of claims 1 to 3, wherein: The impedance change detection circuit comprises a high-frequency AC signal loading circuit and a voltage detection circuit, and the voltage detection circuit is used to determine the time when the impedance change caused by the target object (2) approaching the detection coil reaches a preset threshold.

5. The method for detecting the position and speed of a target object based on the change of coil impedance according to claim 4, wherein: The voltage detection circuit includes a voltage amplitude detection circuit and a voltage phase detection circuit.

6. The method for detecting the position and speed of a target object based on coil impedance change according to claim 4, wherein: The target object (2) is an underwater robot.

7. The method for detecting the position and speed of a target object based on coil impedance change according to claim 1, wherein: In step S2, the impedance change detection circuit also records the impedance change of at least two detection coils caused by the target object (2) approaching the detection coils, and determines the offset of the target object (2) from the preset motion trajectory based on the impedance change.

8. A target position and speed detection system based on coil impedance change, used to implement the target position and speed detection method based on coil impedance change according to any one of claims 1 to 7, characterized in that: It comprises at least two detection coils arranged at predetermined positions along a preset motion track of a target object (2) and an impedance change detection circuit respectively connected to each detection coil.

9. The target position and speed detection system based on coil impedance change according to claim 8, characterized in that: The target object (2) is an underwater robot, at least two detection coils are arranged close to a charging system of the underwater robot, and a target object (2) posture adjustment control module is also arranged between the target object (2) and the impedance change detection circuit.

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