Receiver positioning and rotation angle estimation system based on photodiodes and leds

Abstract

The application discloses a receiver positioning and rotation angle estimation system based on a photodiode and an LED, proposes a new light positioning method and a rotation angle estimation method, and obtains a high-precision two-dimensional positioning result for the needs of indoor positioning, robot navigation, game equipment and the like. The method collects incident light signals through a PD array, and can directly obtain two-dimensional plane coordinates and a rotation angle of the receiver through a positioning algorithm and a rotation angle estimation algorithm. Compared with existing three-dimensional indoor light positioning methods such as an angle of arrival, a time of arrival and a received signal strength, the application has the advantages that: the application does not depend on a synchronous or demodulation system; the operation complexity is low; only a PD array is needed to receive a signal; the application can provide a centimeter-level precision within a certain range; the application can directly obtain a rotation angle estimation; the application does not depend on fixed light power; and the PD array can support high-speed visible light communication.

Description

Technical Field

[0001] This invention belongs to the field of indoor optical positioning, and particularly relates to a receiver positioning and rotation angle estimation system based on photodiodes and LEDs. Background Technology

[0002] Positioning technology is one of the core technologies fundamental to the Internet of Things (IoT) and artificial intelligence (AI) applications. Visible light positioning systems, characterized by low cost and high accuracy, possess enormous market potential. Currently, among visible light-based indoor positioning technologies, visible light positioning algorithms based on Angle of Arrival (AOA) are considered the most promising indoor positioning methods due to their low cost, high accuracy, and low computational complexity. However, existing visible light AOA positioning algorithms rely on complex algorithms such as neural networks or numerical integration, resulting in high implementation costs; or they depend on cameras, leading to high costs, high power consumption, and lack of support for high-bandwidth visible light communication; or they require electronic compasses to provide rotation angle measurements. Therefore, existing optical positioning AOA algorithms are difficult to apply to low-cost mobile devices, and the numerous components and complex algorithms required for two-dimensional positioning further complicate their application. Summary of the Invention

[0003] The purpose of this invention is to provide a receiver positioning and rotation angle estimation system based on photodiodes and LEDs. By employing a photodiode (PD) array, a positioning system algorithm using two symmetrical LEDs is designed that does not rely on neural networks or numerical integration. This algorithm is simple, reduces hardware costs, supports high-speed visible light communication, and provides rotation angle estimation. This solves the technical problems of high hardware cost, high computational complexity, high equipment complexity, lack of support for wireless optical communication, and the need for additional devices to provide rotation angle in wireless optical positioning systems.

[0004] To solve the above-mentioned technical problems, the specific technical solution of the present invention is as follows:

[0005] A highly efficient visible light positioning and rotation angle estimation system based on photodiodes and light-emitting diodes includes the following steps:

[0006] Step 1: Measure the three-dimensional coordinates of two symmetrically distributed light-emitting diodes (LEDs) and denote them as coordinate vectors l1 and l2.

[0007] Step 2: Combine four photodiodes (PDs) facing different directions into an array to serve as a receiver;

[0008] Step 3: Place the receiver horizontally with its central axis pointing in a certain absolute direction. Determine the receiver's position using the vector u = [u...]. x ,u y ,u z ] T express;

[0009] Step 4: Measure the vertical distance between the LED and the receiver at this point.

[0010] l z，k -u z =h Lu (1);

[0011] The vertical distance is represented by h. Lu , l z，k Let be the z-coordinate of the k-th LED;

[0012] Step 5: Define the rotation angle β of the receiver relative to the absolute direction, and the rotation matrix G from the world coordinate system to the relative coordinate system.

[0013]

[0014] Step 6: The normalized incident light direction vector of the k-th LED in the relative coordinate system is derived through calculation.

[0015]

[0016] l k This refers to the coordinate vector of the k-th LED;

[0017] Step 7: Substitute formulas (1) and (2) into formula (3).

[0018]

[0019] Where r x，k Let r be the x-direction component of the normalized incident light direction vector of the k-th LED in the relative coordinate system. y，k The y-direction component of the normalized incident light direction vector of the k-th LED in the relative coordinate system, r z，k The z-direction component of the normalized incident light direction vector of the k-th LED in the relative coordinate system; l x，k Let x be the x-coordinate of the k-th LED; l y，k Let y be the y-coordinate of the k-th LED;

[0020] Step 8: Using formula (4), obtain the known parameter h. Lu and the parameter to be measured r z，k Contact

[0021]

[0022]

[0023] Formula (5.2) defines a circle whose center lies at (l x，k , ly，k And the radius is

[0024]

[0025] Step 9, Set l x,1 =d,l x,2 =-d,l y,1 =l y,2 =0 and combined with formulas (5) and (6) to obtain the user coordinate calculation method

[0026]

[0027] We obtain a set of two user coordinates that are mirror-symmetric about the x-axis, where d is an assumed distance value;

[0028] According to the cross product of vectors

[0029]

[0030] The final receiver position coordinates are determined by making a judgment.

[0031] Step 10: Based on the estimated receiver position, obtain the received light direction vector in the world coordinate system.

[0032]

[0033] Let β be an estimate of the rotation angle. The position vector u is an estimate, thus yielding the relationship between the rotation angle β and the position vector u.

[0034]

[0035] in

[0036]

[0037]

[0038] Step 11: According to formula (10), we can further obtain

[0039]

[0040] The receiver positioning and rotation angle estimation system based on photodiodes and LEDs of the present invention has the following advantages:

[0041] This invention uses a low-cost hardware platform to achieve two-dimensional optical positioning and rotation angle estimation functions. It only contains two symmetrical LEDs, a photodiode array, and a low-speed signal processing unit. It does not rely on complex algorithms such as neural networks or numerical integration, and does not require an electronic compass. By taking advantage of the fixed vertical distance in two-dimensional coordinate estimation and applying the rotation angle estimation algorithm (Formulas 9 and 10), relatively accurate indoor two-dimensional positioning can be obtained, and it can support high-speed visible light communication.

[0042] This invention proposes an optical positioning method and a rotation angle estimation method, which provide high-precision two-dimensional positioning results for applications such as indoor positioning, robot navigation, and gaming devices. The method acquires incident light signals through a PD array and, using the proposed positioning and rotation angle estimation algorithms, directly obtains the receiver's two-dimensional plane coordinates and rotation angle through simple expressions. Compared with existing three-dimensional indoor optical positioning methods based on Angle of Arrival (AOA), Time of Arrival (TOA), and Received Signal Strength (RSS), this invention offers the following advantages: it does not rely on synchronization or modulation / demodulation systems; it has low computational complexity; it only requires a PD array to receive signals; it can provide centimeter-level accuracy within a certain range; it can directly obtain rotation angle estimates; it does not rely on fixed optical power; and the PD array can support high-speed visible light communication. Attached Figure Description

[0043] Figure 1 This invention relates to an indoor positioning system based on two symmetrical LEDs and a PD array.

[0044] Figure 2 This is a schematic diagram of the mirror positioning and rotation angle estimation of the present invention.

[0045] Figure 3 This is a framework diagram of the two-dimensional optical positioning system of the present invention. Detailed Implementation

[0046] To better understand the purpose, structure, and function of this invention, the following detailed description of a receiver positioning and rotation angle estimation system based on photodiodes and LEDs is provided in conjunction with the accompanying drawings.

[0047] System framework such as Figure 3 As shown, it includes two mirror-symmetrical LEDs, a photodiode array, and a low-speed signal processing unit.

[0048] First, measure the three-dimensional coordinates of two symmetrically distributed LEDs, denoted as coordinate vectors l1 and l2, for example (1 m, 0 m, 0.5 m) and (-1 m, 0 m, 0.5 m);

[0049] Then, the four photodiodes facing different directions are combined into an array to serve as a receiver;

[0050] Place the receiver horizontally with its central axis pointing in a certain absolute direction, and represent the receiver's position using a vector u = [u x ,u y ,u z ] T express;

[0051] Assuming the receiver moves only on a single plane, the distance (i.e., height) between the plane containing the LED and the plane containing the receiver is fixed. The vertical distance between the LED and the receiver at this point is then measured.

[0052] l z,k -u z =h Lu (1);

[0053] Define the rotation angle β of the receiver relative to the absolute direction, and obtain the rotation matrix G from the world coordinate system to the relative coordinate system.

[0054]

[0055] The normalized incident light direction vector of the k-th LED in the relative coordinate system is obtained through calculation and derivation.

[0056]

[0057] Substituting equations (1) and (2) into equation (3), we can obtain the incident light direction vector as follows:

[0058]

[0059] Formula (4) can be used to obtain the known parameter h. Lu and the parameter to be measured r z,k Contact

[0060]

[0061]

[0062] Formula (5.2) defines a circle whose center lies at (l x,k ,l y,k And the radius is

[0063]

[0064] Using formulas (5) and (6), the known parameter h can be obtained. Lu and the parameter to be measured r z,k By connecting these factors, and through further simplification and calculation, the user's coordinates can be calculated.

[0065] Assume l x,1 =d,l x,2 =-d,l y,1 =l y,2 =0 and combined with formulas (5) and (6), the user coordinate calculation method can be obtained.

[0066]

[0067] According to formula (7), a set of two user coordinates that are mirror-symmetric about the x-axis can be obtained, which can be used to determine the vector cross product.

[0068]

[0069] The final receiver position coordinates are determined by making a judgment.

[0070] Based on the estimated receiver position, the direction vector of the received light in the world coordinate system can be obtained.

[0071]

[0072] Therefore, the relationship of the rotation angle β can be obtained.

[0073]

[0074] in These are the estimates of the rotation angle β and the position vector u, respectively. Therefore, the relationship between the rotation angle β and u can be obtained.

[0075]

[0076] and

[0077]

[0078] According to (10), we can further obtain

[0079]

[0080] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.

Claims

1. A highly efficient visible light positioning and rotation angle estimation system based on photodiodes and light-emitting diodes, characterized in that, Includes the following steps: Step 1: Measure the three-dimensional coordinates of two symmetrically distributed LEDs, and denote them as coordinate vectors. 1 and 2; Step 2: Combine four photodiodes (PDs) facing different directions into an array to serve as a receiver; Step 3: Place the receiver horizontally with its central axis pointing in a certain absolute direction, and use a vector to determine the receiver's position. express; Step 4: Measure the vertical distance between the LED and the receiver at this point. (1)； The vertical distance is represented as Let be the z-coordinate of the k-th LED; Step 5: Define the rotation angle of the receiver relative to the absolute direction. Rotation matrix from world coordinate system to relative coordinate system : (2)； Step 6: The normalized incident light direction vector of the k-th LED in the relative coordinate system is derived through calculation. (3)； This refers to the coordinate vector of the k-th LED; Step 7: Substitute formulas (1) and (2) into formula (3). (4)； in Let x be the x-direction component of the normalized incident light direction vector of the k-th LED in the relative coordinate system. Let y be the normalized incident light direction vector of the k-th LED in the relative coordinate system. Let z be the z-direction component of the normalized incident light direction vector of the k-th LED in the relative coordinate system; Let x be the x-coordinate of the k-th LED; Let y be the y-coordinate of the k-th LED; Step 8: Using formula (4), obtain the known parameters. and the parameters to be measured Contact (5.1)； (5.2)； Formula (5.2) defines a circle whose center is at... And the radius is (6)； Step 9, Settings Combined with formulas (5.1), (5.2), and (6), the user coordinate calculation method is obtained. ； (7) We obtain a set of two user coordinates that are mirror-symmetric about the x-axis, where d is an assumed distance value; Based on the cross product of vectors: (8) ； The final receiver position coordinates are determined by making a judgment. Step 10: Based on the estimated receiver position, obtain the received light direction vector in the world coordinate system: (9)； Let β be an estimate of the rotation angle. The position vector u is an estimate, thus yielding the rotation angle. Relationship: （10）； in: ； (11)； Step 11: According to formula (10), we can further obtain (12)。

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