Positioning antenna, positioning method and system, and shopping cart control method and system

Abstract

A positioning antenna unit and the related use thereof. The positioning antenna unit (104(1)) comprises two identical directional antennas arranged together in different orientations, wherein the two directional antennas are symmetrically arranged along a vertical plane, and an included angle between the maximum radiation directions of the two directional antennas satisfies partial overlap of horizontal effective coverage areas (103) of the two directional antennas. Since the two directional antennas communicate with a positioned object at the same point, the impact of the external environment on signal transmission is present for both antennas. That is to say, RSSI values of positioning signals received by the two antennas similarly increase or decrease under the impact of the external environment. The similarly increased or decreased values are eliminated during difference calculation. On the basis of the symmetric positioning antenna, the problem in the prior art of inaccurate positioning results caused by the impact of the external environment on wireless signal transmission can be effectively solved.

Description

Positioning antenna, positioning method and system, shopping cart control method and system Technical Field

[0001] This invention belongs to the field of wireless positioning technology, specifically relating to a technique for determining the location of a target object by means of received signal strength (RSSI) values, and in particular, determining the relative position of the target object with respect to a target boundary or interface. Background Technology

[0002] Installing locking wheels (one, two, or all) on shopping carts, which lock when the cart attempts to cross the supermarket boundary, is currently a proven and effective method for preventing theft. One key technical challenge in this method is determining when the cart is attempting to cross the boundary.

[0003] US Patent No. 5598144 discloses a shopping cart anti-theft method. This method involves installing buried cables along the boundary of the area accessible to shopping carts outside the supermarket (typically a parking lot boundary). These buried cables radiate signals at close range. Signal receivers are installed inside the wheels to receive the radiated signals from the buried cables. When the shopping cart attempts to cross the boundary from the inside out, the wheels pass over the buried cables, and the signal receivers receive the radiated signals. Based on the signals received from the buried cables, the controller activates a locking mechanism to lock the wheels.

[0004] The disadvantages of this method are: 1. Buried cables are expensive. 2. The ground needs to be dug up for cable installation, which is inconvenient and costly.

[0005] US Patent No. 8463540 uses a directional antenna instead of buried cables. By placing a base station at the boundary where shopping carts are prohibited, the base station sends a locking command to the signal coverage area of ​​the directional antenna, forming a locked zone. The signal coverage area of ​​the directional antenna covers the boundary where shopping carts are prohibited. When a shopping cart attempts to cross the boundary, the wheels enter the locked zone. The wheel's signal receiver receives the locking command from the directional antenna, and the controller, based on the locking command received from the base station, activates the locking mechanism to lock the wheels.

[0006] The drawback of this method is that even narrow-beam directional antennas have blade-shaped lobes, making it difficult to form a very narrow line of radiation. Instead, they cover a relatively wide area, making it difficult to accurately determine whether a shopping cart is attempting to cross the boundary. This can easily lead to shopping carts that are moving normally near the boundary (e.g., being pushed parallel to the boundary within the boundary) being mistakenly locked. A better solution proposed in this patent is to enclose the boundary with a fence, maintaining a sufficiently wide entrance / exit for pedestrians and vehicles, and then placing a base station at the entrance / exit. However, enclosing the boundary outside the entrance / exit is also very costly. Furthermore, the actual radiation range of a directional antenna does not have a clear boundary. This patent uses RSSI values ​​to determine whether a shopping cart has entered the locking area, but RSSI values ​​fluctuate. If the threshold is set too high, missed locking is likely. If the threshold is set too low, the probability of false locking increases. Moreover, signal strength is very susceptible to environmental interference. Using an absolute threshold as the criterion, the effective coverage area of ​​the antenna (the area with RSSI greater than the threshold) will change under different weather conditions, pedestrian activity, and object obstruction, resulting in poor stability. Under good conditions, an antenna that can normally cover the entire target area may fail to do so under poor conditions, leading to vulnerabilities in the anti-theft system. Summary of the Invention

[0007] This invention addresses the problem of determining whether a shopping cart is attempting to cross a boundary by proposing a positioning method suitable for determining the relative position of the object being located with respect to a target vertical plane (such as the vertical projection line and the plane corresponding to the boundary of a supermarket parking lot), as well as various applications.

[0008] This invention first proposes a symmetrical positioning antenna unit, comprising two identical directional antennas arranged together with different orientations. The two directional antennas are symmetrically arranged along a straight plane, and the included angle (in their maximum radiation directions) satisfies the condition that the effective horizontal coverage areas of the two directional antennas partially overlap. Here, the effective coverage area refers to the signal coverage range within which the antenna can effectively transmit data to the target. Structurally, "arranged together" means that the two directional antennas are mounted on the same carrier, even if this carrier is detachable; at least in use, the carrier is a single unit. Effectively, it means that for the target object communicating with the positioning antenna, the two directional antennas can be considered to be communicating with the target object from the same point; that is, compared to the distance between the positioning antenna and the target object during operation, the distance between the two directional antennas is negligible. The above explanation regarding "arranged together" applies to every instance of "arranged together" mentioned below.

[0009] When the aforementioned positioning antenna unit is used to locate the object being located, it can be used as a transmitter or a receiver.

[0010] When using the transmitter, the positioning principle is as follows: two directional antennas transmit signals of the same power for positioning (hereinafter referred to as positioning signals) from the same point. The object being positioned receives the positioning signals emitted by the two directional antennas. Since the two directional antennas are symmetrical along the vertical plane of the positioning antenna but have different orientations, when the object being positioned is on the vertical plane of the positioning antenna, the received signal strength (RSSI) of the positioning signals received by the object from the two directional antennas is the same. When the object being positioned is not on the vertical plane of the positioning antenna, the RSSI values ​​of the positioning signals received by the object from the two directional antennas will be different. By comparing the RSSI values ​​of the positioning signals from the two directional antennas, it can be determined whether the object being positioned is located on the vertical plane of the positioning antenna or is biased towards one side of the vertical plane of the positioning antenna.

[0011] When used as a receiver, its positioning principle is as follows: two directional antennas receive the same positioning signal emitted by the object being positioned at the same time from the same point. Since the two directional antennas are symmetrical along the vertical plane of the positioning antenna but have different orientations, when the object being positioned is on the vertical plane of the positioning antenna, the RSSI values ​​of the positioning signals received by the two directional antennas are the same. When the object being positioned is not on the vertical plane of the positioning antenna, the RSSI values ​​of the positioning signals received by the two directional antennas will be different. By comparing the RSSI values ​​of the positioning signals received by the two directional antennas, it can be determined whether the object being positioned is located on the vertical plane of the positioning antenna or is biased towards one side of the vertical plane of the positioning antenna.

[0012] Since the two directional antennas communicate with the target object at the same point, the influence of the external environment on signal transmission exists for both antennas. This means that the RSSI values ​​of the positioning signals received by both antennas will increase or decrease under the influence of the external environment, and this increase or decrease will be eliminated during comparison (difference calculation). Therefore, this symmetrical positioning antenna can effectively solve the problem of inaccurate positioning results caused by the influence of the external environment on wireless signal transmission in existing technologies.

[0013] Comparing the positioning principles used at the transmitting and receiving ends reveals that when used as a transmitting antenna, to enable the target object to identify which directional antenna the received positioning signal originates from, separate identification information needs to be configured for each directional antenna. This results in the target object receiving positioning signals from different directional antennas not being the same signal emitted from the same source at the same time. However, when the positioning antenna is used as a receiving antenna, all directional antennas can simultaneously receive the same positioning signal emitted from the same source at the same time from the target object. Therefore, the positioning antenna unit of this invention is more suitable for use at the receiving end to achieve better positioning results.

[0014] According to the positioning principle of the positioning antenna unit of the present invention, when the object to be positioned is close to the vertical plane of the positioning antenna, both directional antennas should be able to successfully receive the positioning signal emitted by the object, or both positioning signals emitted by the directional antennas should be successfully received by the object. Therefore, when the object to be positioned is close to the vertical plane of the positioning antenna, the effective horizontal coverage areas of the two directional antennas should respectively cover the object. Therefore, the positioning antenna unit of the present invention requires that the effective horizontal coverage areas of the two directional antennas partially overlap on both sides of the vertical plane of the target. Ideally, the shape of the effective horizontal coverage area of ​​a directional antenna is the same as the shape of its horizontal radiation pattern lobe. Theoretically, when setting up two directional antennas, the effective horizontal coverage areas of the two directional antennas can partially overlap by making the horizontal radiation pattern lobes of the directional antennas partially overlap. However, it is understood that the radiation pattern is an idealized simulation result. Based on the working principle of the positioning antenna unit of the present invention, when setting up two directional antennas, it is best to test the actual effective coverage area of ​​the directional antennas experimentally, and then, with the beamwidth of the simulated radiation pattern as a reference, determine the appropriate angle range between the two directional antennas based on the actual tested effective coverage area.

[0015] This invention provides a relatively simple method for determining the included angle between two directional antennas: the horizontal included angle between the two directional antennas is equal to or approximately equal to the horizontal beamwidth of the directional antenna.

[0016] In practical applications, the positioning antenna unit of the present invention can be directly configured as a positioning antenna based on a single vertical plane symmetric structure and directly used as a receiving or transmitting antenna in a positioning device.

[0017] For example, a positioning device can be formed by combining a positioning antenna unit as a receiving antenna with a receiving and processing control unit. The object to be positioned is equipped with an omnidirectional transmitting antenna and a transmitting control unit to form the transmitting end. The transmitting control unit generates a positioning signal and broadcasts it through the omnidirectional transmitting antenna. The positioning antenna outputs the positioning signals received by its two directional antennas to the receiving and processing control unit. The receiving and processing control unit calculates and compares the RSSI values ​​of the positioning signals received by the two directional antennas, and then determines the relative position of the object to be positioned relative to the vertical plane of the positioning antenna based on the comparison results. In this example, the receiving and processing control unit preferably includes two signal processing modules (preferably a Bluetooth communication module) and a controller (preferably an MCU). Each of the two directional antennas of the positioning antenna is connected to a signal processing module, and the two signal processing modules are connected to the controller. The two signal processing modules calculate and output the RSSI values ​​of the positioning signals received by the two directional antennas. The controller compares the RSSI values ​​of the signals received by the two directional antennas and determines the relative position of the object to be positioned.

[0018] The positioning antenna unit of the present invention can also be used to construct a receiving or transmitting antenna, which can then be further used in a positioning device.

[0019] For example, multiple positioning antenna units of the present invention can be combined to form a first novel positioning antenna based on a single vertical plane symmetry structure, including multiple pairs (two or more pairs) of directional antennas arranged together. The two positioning antennas in each pair of directional antennas are identical and symmetrically arranged along the same vertical plane. The effective horizontal coverage areas of the two directional antennas in each pair of positioning antennas partially overlap. Here, each pair of directional antennas is a positioning antenna unit of the present invention. Further, this novel positioning antenna based on a single vertical plane symmetry structure can be combined with a receiving antenna and a receiving processing control unit to form a positioning device. The positioning antenna outputs the positioning signals received by its multiple pairs of directional antennas to the receiving processing control unit. The receiving processing control unit calculates the RSSI value of the positioning signal received by each directional antenna and compares the RSSI values ​​of the directional antennas located on both sides of the vertical plane of the positioning antenna. Then, based on the comparison results, it determines the relative position of the object being positioned relative to the vertical plane of the positioning antenna.

[0020] There are several comparison methods available. For example, the first method is to add up the RSSI values ​​of all directional antennas on one side of the vertical plane of the positioning antenna and compare them with the sum of the RSSI values ​​of all directional antennas on the other side. Alternatively, the RSSI values ​​of each pair of directional antennas can be compared separately, and the final comparison result can be obtained based on the individual comparison results of each pair of directional antennas. (For example, when all individual comparison results are consistent (e.g., the RSSI value of the first directional antenna in each pair is greater than the RSSI value of the second directional antenna), the consistent result is taken as the final comparison result; if they are inconsistent, the positioning is considered to have failed.) Another example is the second method, which uses the majority of individual comparison results as the final comparison result. (e.g., if there are three pairs of directional antennas, and the RSSI values ​​of the first directional antennas in two pairs are greater than the RSSI values ​​of the second directional antennas, while the RSSI value of the first directional antenna in another pair is less than the RSSI value of the second directional antenna, then the final comparison result is that the RSSI value of the first directional antenna is greater than the RSSI value of the second directional antenna, thus determining that the object being positioned is currently located on the first side of the vertical plane of the positioning antenna.)

[0021] For example, based on the positioning antenna unit of this invention, additional directional antennas can be added to form a second new positioning antenna based on a single vertical plane symmetry structure. This includes multiple pairs (two or more pairs) of directional antennas arranged together, with two identical directional antennas in each pair, symmetrically arranged along the same vertical plane. The effective horizontal coverage areas of at least two of the directional antennas in one pair partially overlap. Here, the at least one pair of directional antennas whose effective horizontal coverage areas partially overlap constitute the positioning antenna unit of this invention. Furthermore, this second positioning antenna based on a single vertical plane symmetry structure is combined with a receiving antenna and a receiving processing control unit to form a positioning device. The positioning antenna outputs the positioning signals received by its multiple pairs of directional antennas to the receiving processing control unit. The receiving processing control unit calculates the RSSI value of the positioning signal received by each directional antenna and compares the RSSI values ​​of the directional antennas located on both sides of the vertical plane of the positioning antenna. Based on the comparison results, the relative position of the object being positioned relative to the vertical plane of the positioning antenna is determined.

[0022] Depending on the specific addition of directional antennas, there are several comparison methods available. In the first case, the effective horizontal coverage areas of the two directional antennas in each pair of added antennas partially overlap. This is the same as the case described above where multiple positioning antenna elements are combined to form a positioning antenna, and the various comparison methods exemplified above can be applied. In the second case, among the added pairs of directional antennas, the effective horizontal coverage areas of the two directional antennas in one or more pairs do not overlap. If the non-overlapping directional antennas cannot simultaneously receive signals from the target object, they are not suitable for individual comparison. When setting comparison rules, the RSSI values ​​of the non-overlapping directional antenna pairs can be added to the RSSI values ​​of one or more overlapping directional antenna pairs on the same side and compared. This comparison is then combined with other individual comparison results to determine the final comparison result. Alternatively, the authenticity of the individual or combined comparison results of other overlapping directional antenna pairs can be determined based on the RSSI values ​​of the non-overlapping directional antenna pairs, thereby determining the final comparison result (e.g., if the RSSI value comparison result of the overlapping directional antenna pairs is that the RSSI value of the first directional antenna is greater than that of the second directional antenna, but the first directional antenna in the non-overlapping directional antenna pairs does not receive a signal, then the individual or combined comparison results of other overlapping directional antenna pairs are considered incorrect, and the positioning fails). In the third case, all additional directional antenna pairs have horizontal effective coverage areas that do not overlap. When setting comparison rules, the RSSI values ​​of the non-overlapping pair of directional antennas can be added together with the RSSI values ​​of the pair of directional antennas constituting the positioning antenna unit on the same side, and then the two sides can be compared to obtain the final comparison result. Alternatively, the authenticity of the comparison result of the RSSI values ​​of the pair of directional antennas constituting the positioning antenna unit can be determined based on the RSSI values ​​of the non-overlapping pair of directional antennas, and then the final comparison result can be determined.

[0023] It can be noted that the second new type of positioning antenna, which is formed by adding other directional antennas based on the positioning antenna unit of the present invention, includes the case of the first new type of positioning antenna formed by combining multiple positioning antenna units of the present invention.

[0024] Based on the various comparison methods described above, it can be seen that regardless of the situation (whether it's a comprehensive judgment of the results of comparing multiple pairs of directional antennas individually; or incorporating the RSSI value of the additional directional antenna into the comparison; or judging the authenticity of the comparison result based on the RSSI value of the additional directional antenna), more directional antennas can effectively correct the judgment errors that may occur when directly using a single positioning antenna element as the directional antenna. Therefore, although multiple pairs of directional antennas increase the cost of the positioning antenna, they can achieve better positioning results.

[0025] For ease of description, the examples above primarily use the positioning antenna as a receiving antenna. If the positioning antenna is used as a transmitting antenna, the structures and comparison methods for various positioning antennas based on a single vertical plane symmetry structure described above are equally applicable. The difference is that the signal transmission direction is reversed. In this case, the positioning device is formed by combining the positioning antenna as a transmitting antenna and a transmission control unit, while the object being positioned is configured with an omnidirectional receiving antenna and a receiving processing control unit to form the receiving end. The transmitting control unit generates positioning signals containing the identification information of the corresponding directional antennas and distributes them accordingly to each directional antenna of the positioning antenna. The receiving processing control unit at the receiving end calculates the RSSI value of the positioning signal from each directional antenna, compares them, and then determines the relative position of the object being positioned relative to the vertical plane of the positioning antenna based on the comparison results.

[0026] Based on the positioning principle of the positioning antenna unit of this invention, it is known that the key to achieving positioning lies in the comparability of RSSI values, that is, the relative magnitude of the RSSI value is consistent with the relative position of the object being positioned relative to the target vertical plane. Correspondingly, its core structural feature is that the directional antenna is symmetrical with respect to the vertical plane. Therefore, it can be conceived that, in addition to the various situations exemplified above, any positioning antenna with a symmetrical structure formed by extending the positioning antenna unit of this invention can achieve the determination of the relative position of the object being positioned relative to the target vertical plane as described in this invention.

[0027] It is also conceivable that any positioning antenna that includes the positioning antenna unit of the present invention (i.e., two identical directional antennas arranged symmetrically along the vertical plane and whose effective coverage area on the horizontal plane partially overlaps) and that uses the comparison of the RSSI values ​​of the symmetrical directional antennas to locate the relative position of the object to be positioned relative to the target vertical plane should be considered an application of the positioning antenna unit of the present invention.

[0028] The following are some other special applications of the positioning antenna unit of this invention.

[0029] The first rather special application scenario: Based on the positioning antenna unit of this invention, an omnidirectional antenna is set at the structural center of the positioning antenna to form a positioning antenna, and the RSSI value of the omnidirectional antenna is used as the condition for performing the comparison.

[0030] The second, more unique application scenario involves setting up three directional antennas in different orientations around the intersection point of two intersecting vertical planes to form a positioning antenna. The first and second directional antennas are symmetrical along the first vertical plane, forming a positioning antenna unit of the present invention. The second and third directional antennas are symmetrical along the second vertical plane, also forming a positioning antenna unit of the present invention.

[0031] The third, more unique application scenario involves four directional antennas arranged in different orientations around the intersection of two intersecting vertical planes, forming a positioning antenna. The first and second directional antennas, with the first vertical plane as their plane of symmetry, constitute one positioning antenna unit of this invention. The second and third directional antennas, with the second vertical plane as their plane of symmetry, also constitute one positioning antenna unit of this invention. The third and fourth directional antennas, with the first vertical plane as their plane of symmetry, also constitute one positioning antenna unit of this invention. The fourth directional antenna and the first directional antenna, with the second vertical plane as their plane of symmetry, also constitute one positioning antenna unit of this invention.

[0032] Based on the aforementioned positioning antenna unit and positioning antenna based on a single vertical plane symmetrical structure, as well as various comparison methods, this invention preferably uses the positioning antenna as the receiving antenna. It further claims a positioning method based on single vertical plane comparison for determining the relative position of the object to be positioned relative to a target vertical plane. This method uses the object to be positioned as the signal transmitting end, and pairs of directional antennas are set as receiving ends along the target vertical plane. The two directional antennas in the pair are identical and symmetrically arranged along the target vertical plane. The horizontal angle between the two directional antennas in the pair is set so that the effective horizontal coverage areas of at least two of the directional antennas in one pair partially overlap. By comparing the RSSI values ​​of the same signal emitted by the object to be positioned received by the directional antennas on both sides of the target vertical plane, it is determined which side of the target vertical plane the object to be positioned is located on.

[0033] The following section lists several typical comparison methods for different settings of directional antennas.

[0034] The first method involves setting two identical directional antennas symmetrically along the target plane, and setting the horizontal angle between the two directional antennas so that the effective coverage areas of the two directional antennas partially overlap.

[0035] The positioning method compares the RSSI values ​​of the same signal emitted by the target object received by two directional antennas to determine which side of the target's vertical plane the target object is located on. The side of the directional antenna with the larger RSSI value is the side where the target object is currently located.

[0036] The second method involves symmetrically setting at least two pairs of directional antennas along the target's horizontal plane. The two antennas in each pair are identical and symmetrical along the target's horizontal plane. The horizontal angle between each pair of directional antennas is set so that the effective horizontal coverage areas of at least two antennas in one pair partially overlap.

[0037] By comparing the sum of the RSSI values ​​of the same signal emitted by the target object and received by directional antennas on both sides of the target's vertical plane, it can be determined which side of the target's vertical plane the target object is located on. The side of the directional antenna with the larger sum of RSSI values ​​is the side where the target object is currently located.

[0038] The third method involves symmetrically setting at least two pairs of directional antennas along the target's horizontal plane. The two antennas in each pair are identical and symmetrical along the target's horizontal plane. The horizontal angle between each pair of directional antennas is set so that the effective horizontal coverage areas of the two antennas in each pair partially overlap.

[0039] The RSSI values ​​of the same signal emitted by the target object and received by the two directional antennas in each pair of directional antennas are compared. The final comparison result is the one where all values ​​are consistent or the majority value is obtained, which determines which side of the vertical plane the target object is located on. The side of the directional antenna with the larger RSSI value in the final comparison result is the side where the target object is currently located.

[0040] Based on the above-described positioning method based on single vertical plane comparison, this invention further claims a positioning system based on single vertical plane comparison, including a positioning device and a target object. The target object is equipped with a signal transmitter. The positioning device includes a positioning antenna disposed on the target vertical plane and a receiving and processing control unit configured for the positioning antenna. The positioning antenna is a positioning antenna based on a single vertical plane symmetrical structure, including at least one pair of directional antennas disposed together. Two directional antennas in each pair are identical and symmetrically arranged along the target vertical plane. The effective horizontal coverage areas of the two directional antennas in the at least one pair partially overlap. The receiving and processing control unit includes a signal processing module equal in number to the directional antennas and a controller for positioning determination. Each directional antenna is connected to a signal processing module, and each signal processing module is connected to the controller. Each signal processing module calculates and outputs the RSSI value of the signal received by the connected directional antenna to the controller. The controller compares the RSSI values ​​of the same signal emitted by the target object received by the directional antennas on both sides of the target vertical plane and determines which side of the target vertical plane the target object is located on based on the comparison result.

[0041] Alternatively, the positioning antenna may consist of only a pair of directional antennas. The controller compares the RSSI values ​​of the same signal emitted by the object being located, received by the two directional antennas in the pair, and determines the side where the directional antenna with the larger RSSI value is located as the current location of the object being located.

[0042] Alternatively, the positioning antenna includes multiple pairs of directional antennas, with at least two of the directional antennas having partially overlapping horizontal effective coverage areas. The controller compares the sum of the RSSI values ​​of the signals received by the directional antennas on one side of the horizontal plane with the sum of the RSSI values ​​of the signals received by the directional antennas on the other side of the horizontal plane. The side containing the directional antennas with the larger sum of RSSI values ​​is determined to be the current location of the object being located.

[0043] Alternatively, the positioning antenna includes multiple pairs of directional antennas, with the effective horizontal coverage areas of two directional antennas in each pair partially overlapping. The controller compares the RSSI values ​​of the same signal emitted by the object being located, received by the two directional antennas in each pair. When the RSSI values ​​of all or most of the directional antennas on one side are greater than the RSSI values ​​of the symmetrical directional antennas, that side is determined to be the side where the object being located is currently located.

[0044] Furthermore, the included angle of each pair of positioning antennas is different.

[0045] This invention further claims a shopping cart control method based on single vertical plane comparison, using the aforementioned positioning method based on single vertical plane comparison. The method uses a shopping cart as the object to be positioned, and includes a braking mechanism on the cart to restrict its movement. The cart is also equipped with functions for receiving commands and sending positioning signals. A positioning antenna with a single vertical plane symmetrical structure is set along the boundary preventing the cart from being pushed out, receiving the positioning signal emitted by the cart. The vertical plane of the positioning antenna corresponds to the boundary preventing the cart from being pushed out. By comparing the RSSI values ​​of the positioning signals received from the cart by directional antennas on both sides of the vertical plane of the positioning antenna, it is determined which side of the boundary preventing the cart from being pushed out is located on. If the cart is positioned outside the boundary preventing the cart from being pushed out, or based on positioning results at different times, it is determined that the cart has moved from inside to outside the boundary preventing the cart from being pushed out, and a locking command is sent to the cart. Upon receiving the locking command, the cart activates the braking mechanism to lock the cart.

[0046] Furthermore, the positioning signal sent by the shopping cart includes the status information of the shopping cart being locked or unlocked. When the shopping cart is located inside the boundary that prevents the shopping cart from being pushed out and is in a locked state, an unlock command is sent to the shopping cart. After receiving the unlock command, the shopping cart activates the braking mechanism to unlock the shopping cart.

[0047] Furthermore, considering the limited effective range of the positioning antenna, when the width of the boundary preventing shopping cart ejection is less than the effective range of the positioning antenna—for example, for controlling shopping carts at supermarket entrances, shopping area entrances, checkout lanes, or entrances / exits of enclosed parking lots (where barriers prevent shopping cart ejection along the parking lot boundary, with only a few entrances / exits for vehicles and / or pedestrians)—a positioning antenna based on a single vertical symmetrical structure can be installed at one end of the boundary preventing shopping cart ejection, with its direction of action facing the other end. The effective range of this antenna covers the width of the boundary preventing shopping cart ejection. Alternatively, two positioning antennas based on a single vertical symmetrical structure can be installed at each end of the boundary preventing shopping cart ejection, with their directions of action opposite each other. The sum of the effective ranges of the two antennas covers the width of the boundary preventing shopping cart ejection. Alternatively, the effective range of each positioning antenna can cover the width of the boundary, and the final positioning result from both antennas can be used to control the locking or unlocking of the shopping cart.

[0048] When the width of the boundary preventing shopping carts from being pushed out is greater than the effective range of the positioning antenna, such as for shopping cart control at the boundary of an open parking lot, positioning antennas based on a single vertical plane symmetrical structure can be set at intervals along the boundary of the parking lot. When selecting the setting points of the positioning antennas, the boundary between every two positioning antennas should be a straight boundary. The interval between two positioning antennas can be covered by the effective range of one of the positioning antennas, or it can be covered by half of the effective range of each of the two positioning antennas, or it can be covered by the effective range of both positioning antennas at the same time.

[0049] Based on the above-described shopping cart control method based on single vertical plane comparison, this invention further claims a shopping cart control system based on single vertical plane comparison, comprising a shopping cart as the object to be located, and a base station for locating and controlling the shopping cart. The shopping cart is equipped with a braking mechanism to limit the cart's movement, and a transceiver for sending positioning signals and receiving control commands.

[0050] The base station includes a positioning antenna for receiving positioning signals, a signal processing module with the same number of directional antennas as the positioning antenna, and a controller for positioning judgment and generating control commands. Optionally, the base station also includes a transmitting antenna for sending control commands (if no transmitting antenna is provided, the control commands can also be sent through one of the directional antennas in the positioning antenna).

[0051] The positioning antenna is the aforementioned positioning antenna based on a single vertical plane symmetrical structure. The positioning antenna is positioned along the boundary line preventing the shopping cart from being pushed out, with the vertical plane of the positioning antenna corresponding to the boundary line. Each directional antenna in the positioning antenna is connected to a signal processing module. Each signal processing module calculates and outputs the RSSI value of the positioning signal received by the connected directional antenna. Each signal processing module is connected to a controller. The controller compares the RSSI values ​​of the positioning signals from the shopping cart received by the directional antennas on both sides of the vertical plane of the positioning antenna to determine which side of the boundary line preventing the shopping cart from being pushed out. When the shopping cart is positioned outside the boundary line, or, based on positioning results at different times, it is determined that the shopping cart has moved from inside to outside the boundary line, the base station sends a locking command to the shopping cart. The shopping cart receives and responds to the locking command, activating the braking mechanism to lock the shopping cart.

[0052] Furthermore, when multiple positioning antennas are required, for example, one positioning antenna can be installed on each side of the entrance and exit of a closed parking lot, or multiple positioning antennas can be installed at intervals along the boundary of an open parking lot. The base station can be configured in the following two ways.

[0053] The first setup method: Connect all positioning antennas to a controller to form a base station.

[0054] In this configuration, the controller compares and judges the RSSI value for each positioning antenna. It can then choose to issue a control command only when the judgment result of any one positioning antenna meets the control condition, or when the judgment results of multiple positioning antennas meet the control condition simultaneously.

[0055] The second setup method: Each positioning antenna or several positioning antennas are grouped together and connected to a controller to form a base station.

[0056] In this configuration, multiple base stations can operate independently, with each base station's controller comparing and judging the RSSI values ​​of its connected positioning antenna and issuing control commands based on the results. Alternatively, multiple base stations can work collaboratively, with each base station outputting its judgment results to a central controller, which then makes control decisions based on the judgment results from all base stations. As an option, one base station can be selected as the primary base station, and the others as secondary base stations, with the primary base station's controller serving as the central controller. All secondary base stations communicate with the primary base station separately (through additional communication modules and antennas). Alternatively, a separate central controller can be set up independently of each base station, with all secondary base stations communicating with the central controller separately (through additional communication modules and antennas).

[0057] It is conceivable that: setting the aforementioned shopping cart control system based on single vertical plane comparison along the parking lot boundary or at the parking lot entrance and exit constitutes a shopping cart anti-theft system based on single vertical plane comparison, which can effectively prevent shopping carts from being pushed out of the supermarket area; setting the aforementioned shopping cart control system based on single vertical plane comparison at the boundary line prohibiting the pushing out of unpaid shopping carts, and using "unpaid shopping cart" as a prerequisite for issuing the locking command, constitutes a merchandise anti-theft system based on single vertical plane comparison, which can effectively prevent unpaid merchandise from being stolen by pushing out of the shopping cart; setting the aforementioned shopping cart control system based on single vertical plane comparison at the entrance of the supermarket shopping area, and using "the shopping cart moving from the inside to the outside of the boundary line prohibiting shopping carts from being pushed out" as a condition for issuing the locking command, constitutes a shopping cart reverse-movement control system based on single vertical plane comparison, which can prevent customers from pushing shopping carts out of the shopping area entrance in the opposite direction.

[0058] For a third, more specific application of the positioning antenna unit of this invention, this invention claims protection for a positioning antenna based on a dual-vertical-plane symmetric structure, comprising multiple directional antennas arranged together, at least four of which form a centrally symmetric structure with the intersection of two mutually perpendicular vertical planes as the central axis. Any two directional antennas that form a symmetrical relationship along the vertical planes (vertical projection forming axial symmetry) are identical. At least one pair of directional antennas symmetrical along a first vertical plane has partially overlapping horizontal effective coverage areas, and at least one pair of directional antennas symmetrical along a second vertical plane has partially overlapping horizontal effective coverage areas. It can be understood that each pair of directional antennas that is vertically symmetrical and has partially overlapping horizontal effective coverage areas constitutes a positioning antenna unit of this invention.

[0059] Furthermore, the plurality of directional antennas are divided into four groups, each located in a right-angle region. The first and second groups are symmetrical along a first vertical plane; the second and third groups are symmetrical along a second vertical plane; the third and fourth groups are symmetrical along a first vertical plane; and the fourth and first groups are symmetrical along a second vertical plane. In any two groups of directional antennas that form a symmetrical relationship along a vertical plane, at least one pair of vertically symmetrical antennas will have partially overlapping horizontal coverage areas.

[0060] Furthermore, the four sets of directional antennas are rotationally symmetrical about the intersection of the two vertical planes at a 90-degree angle. The four directional antennas forming this 90-degree rotational symmetry are identical.

[0061] Furthermore, the plurality of directional antennas consists of four identical antennas, which are rotationally symmetrical about the intersection of the two vertical planes as a central axis. The horizontal coverage areas of any two directional antennas that form a symmetrical relationship along the vertical planes partially overlap.

[0062] Alternatively, the plurality of directional antennas may include one or more pairs of directional antennas disposed on a first vertical plane or a second vertical plane.

[0063] This positioning antenna is preferably used as a receiving antenna, which can be used to determine which of the four right-angled regions the object being located is in, separated by two mutually perpendicular vertical planes. For example, by installing the positioning antenna at a right-angled corner of a parking lot boundary, so that the vertical projection lines of the two vertical planes coincide with the two right-angled sides of the corner, and using a shopping cart as the object being located, the antenna can be used to determine whether the shopping cart near the corner is located inside or outside the parking lot boundary.

[0064] When locating an object using this positioning antenna, the first vertical plane can be selected first, treating the positioning antenna as a single-vertical-plane symmetrical structure. The RSSI values ​​of the directional antennas on both sides of the first vertical plane are compared to determine which side of the first vertical plane the object is located on. Then, the second vertical plane is selected, and the positioning antenna is treated as a single-vertical-plane symmetrical structure. The RSSI values ​​of the directional antennas on both sides of the second vertical plane are compared to determine which side of the second vertical plane the object is located on. Finally, the two comparison results are combined to determine which right-angle region among the four right-angle regions formed by the two vertical planes the object is located in.

[0065] Based on the aforementioned positioning antenna with a dual-vertical-plane symmetry structure, this invention further claims a positioning method based on dual-vertical-plane comparison, used to determine the relative position of a target object with respect to two mutually perpendicular target vertical planes. This method uses the target object as the signal transmitter, and sets up multiple directional antennas in a centrally symmetrical structure with the intersection of the two target vertical planes as the central axis. Two directional antennas forming a symmetrical relationship along any target vertical plane are identical. The included angle between two directional antennas symmetrical along the target vertical planes is set such that at least one pair of directional antennas symmetrical along the first target vertical plane has partially overlapping horizontal coverage areas, and at least one pair of directional antennas symmetrical along the second target vertical plane has partially overlapping horizontal coverage areas. By comparing the RSSI values ​​of the signals emitted by the target object received by the directional antennas on both sides of a target vertical plane, it is determined which side of the target vertical plane the target object is located on. Then, combining the two comparison results, it is further determined which of the four right-angle regions formed by the two target vertical planes the target object is located in.

[0066] In the above positioning method, when comparing the RSSI values ​​of the signals emitted by the target object received by the directional antennas on both sides of a target vertical plane, the various comparison methods described above for single vertical plane positioning antennas can be applied according to the setting of the directional antennas.

[0067] This invention claims a method for controlling a shopping cart to move backwards within an aisle, applying the aforementioned positioning method based on dual vertical plane comparison to supermarket shopping cart control. The method includes a braking mechanism on the shopping cart to limit its movement, as well as functions for sending positioning signals and receiving and responding to commands. Two positioning antennas, based on a dual vertical plane symmetrical structure as described above, are respectively positioned on either side of the aisle. These two antennas are laterally aligned along a boundary line perpendicular to the length of the aisle, preventing the shopping cart from moving backwards. The first and second vertical planes of the first positioning antenna correspond to the boundary line preventing backward movement and the first side boundary of the aisle, respectively. The first and second vertical planes of the second positioning antenna correspond to the boundary line preventing backward movement and the second side boundary of the aisle, respectively. The RSSI values ​​of the directional antennas on both sides of the second vertical plane of the first positioning antenna are compared to determine whether the shopping cart is located inside the first side boundary of the aisle. Similarly, the RSSI values ​​of the directional antennas on both sides of the second vertical plane of the second positioning antenna are compared to determine whether the shopping cart is located inside the second side boundary of the aisle. Combining the two comparison results, the method determines whether the shopping cart is within the aisle. The RSSI values ​​of the directional antennas on both sides of the first vertical plane of the first or second positioning antenna are compared to determine which side of the boundary preventing the shopping cart from being pushed out backwards. Alternatively, the RSSI values ​​of the directional antennas on both sides of the first vertical plane of the first and second positioning antennas are compared separately, and the shopping cart is determined to be on which side of the boundary preventing the shopping cart from being pushed out backwards based on the same comparison result. The positioning results at different times are compared. When the shopping cart moves backwards from the inside to the outside of the boundary preventing the shopping cart from being pushed out backwards, a locking command is sent to the shopping cart. The shopping cart receives and responds to the locking command, activating the braking mechanism to lock the shopping cart. This method can be used to prevent customers from pushing shopping carts out backwards from the entrance of the shopping area.

[0068] Based on the aforementioned positioning method based on dual vertical plane comparison, this invention further constructs a positioning system based on dual vertical plane comparison for locating an object passing through a target boundary. The system includes a positioning device and the object being located. The object is equipped with a signal transmitter. The positioning device includes two positioning antennas with a dual vertical plane symmetrical structure (described above) positioned at both ends of the target boundary, several signal processing modules, and a controller for comparison and judgment. Each directional antenna of the two positioning antennas is connected to a signal processing module. Each signal processing module calculates and outputs the RSSI value of the signal received by the connected directional antenna. The first vertical plane of the first positioning antenna and the first vertical plane of the second positioning antenna are both aligned with the target boundary. The controller compares the RSSI values ​​of the directional antennas on both sides of the second vertical plane of the first positioning antenna to determine whether the object being located is inside the first end of the target boundary. It also compares the RSSI values ​​of the directional antennas on both sides of the second vertical plane of the second positioning antenna to determine whether the object being located is inside the second end of the target boundary. Combining the two comparison results, the controller determines whether the object being located is within the width range of the target boundary. The controller compares the RSSI values ​​of the directional antennas on both sides of the first vertical plane of the first positioning antenna or the second positioning antenna to determine which side of the target boundary the object to be located is located on. Alternatively, it compares the RSSI values ​​of the directional antennas on both sides of the first vertical plane of the first positioning antenna and the second positioning antenna respectively, and determines which side of the target boundary the object to be located is located on based on the same comparison result.

[0069] As an alternative, the positioning device is equipped with only one controller, and the first positioning antenna and the second positioning antenna are respectively connected to this controller through a signal processing module.

[0070] As an alternative, the positioning device is configured with a controller for each of the two positioning antennas.

[0071] Specifically, the first positioning antenna serves as the main positioning antenna and is configured with a main controller. The signal processing modules connected to each directional antenna in the first positioning antenna are respectively connected to the main controller. The second positioning antenna serves as the auxiliary positioning antenna and is configured with an auxiliary controller. The signal processing modules connected to each directional antenna in the second positioning antenna are respectively connected to the auxiliary controller.

[0072] There are at least two methods for comparison and judgment:

[0073] In the first method, the main controller compares the RSSI values ​​of the directional antennas on both sides of the second vertical plane of the first positioning antenna, while the auxiliary controller compares the RSSI values ​​of the directional antennas on both sides of the second vertical plane of the second positioning antenna, and sends the comparison results to the main controller. The main controller then determines whether the object being positioned is located within the width range of the target boundary based on the combined comparison results. Alternatively, the main controller compares the RSSI values ​​of the directional antennas on both sides of the first vertical plane of the first positioning antenna to determine which side of the target boundary the object is located on.

[0074] The second method involves the main controller comparing the RSSI values ​​of the directional antennas on both sides of the second vertical plane of the first positioning antenna with the RSSI values ​​of the directional antennas on both sides of the first vertical plane. The auxiliary controller compares the RSSI values ​​of the directional antennas on both sides of the second vertical plane of the second positioning antenna with the RSSI values ​​of the directional antennas on both sides of the first vertical plane. If the comparison results of the RSSI values ​​of the directional antennas on both sides of the first vertical plane of the two positioning antennas are different, the positioning is considered to have failed. If the results are the same, the main controller determines which side of the target boundary the object being positioned is located on based on the same comparison result.

[0075] This invention further claims a shopping cart control method based on dual vertical plane comparison, using the aforementioned positioning system based on dual vertical plane comparison for supermarket shopping cart control. The method uses the shopping cart as the object to be positioned, equips it with a braking mechanism to restrict its movement, and provides both command receiving and positioning signal sending capabilities. Two positioning antennas with a dual vertical plane symmetrical structure are positioned at either end of a boundary line (e.g., a parking lot entrance / exit boundary) to receive positioning signals from the shopping cart. The first vertical planes of the two positioning antennas correspond to the boundary line. By comparing the RSSI values ​​of the directional antennas on both sides of the second vertical plane of the two positioning antennas, it is determined whether the shopping cart is within the width of this boundary line. The RSSI values ​​of the directional antennas on both sides of the first vertical plane of either the first or second positioning antenna are compared to determine which side of the boundary line the shopping cart is on. Alternatively, the RSSI values ​​of the directional antennas on both sides of the first vertical plane of both the first and second positioning antennas are compared, and the same comparison result determines which side of the boundary line the shopping cart is on. When the shopping cart is positioned outside a boundary that prevents it from being pushed out, or, based on positioning results at different times, it is determined that the shopping cart has moved from the inside to the outside of a boundary that prevents it from being pushed out, a locking command is sent to the shopping cart. Upon receiving the locking command, the shopping cart activates its braking mechanism to lock the cart.

[0076] Furthermore, the positioning signal sent by the shopping cart includes the status information of the shopping cart being locked or unlocked. When the shopping cart is located inside a boundary line that prevents the shopping cart from being pushed out and is in a locked state, an unlock command is sent to the shopping cart. After receiving the unlock command, the shopping cart activates the braking mechanism to unlock the shopping cart.

[0077] Based on the aforementioned shopping cart control method based on dual vertical plane comparison, this invention further claims a shopping cart control system based on dual vertical plane comparison, comprising a shopping cart as the object to be located, and a base station for locating and controlling the shopping cart. The shopping cart is equipped with a braking mechanism to limit the cart's movement, and a transceiver for sending positioning signals and receiving control commands.

[0078] The base station is equipped with a positioning antenna for receiving positioning signals, a signal processing module with the same number of directional antennas as the positioning antenna, and a controller for positioning judgment and generating control commands. Optionally, the base station is also equipped with a transmitting antenna for sending control commands (if no transmitting antenna is configured, the control commands can also be sent through the positioning antenna).

[0079] The positioning antenna is the aforementioned positioning antenna based on a dual vertical symmetric structure. The positioning antenna includes a first positioning antenna and a second positioning antenna respectively disposed at both ends of a boundary line that prohibits the shopping cart from being pushed out. The first vertical planes of the first positioning antenna and the second positioning antenna overlap and correspond to the boundary line that prohibits the shopping cart from being pushed out.

[0080] Each directional antenna in the positioning antenna is connected to a signal processing module. Each signal processing module calculates and outputs the RSSI value of the positioning signal received by the connected directional antenna. Each signal processing module is connected to a controller. The controller compares the RSSI values ​​of the directional antennas on both sides of the second vertical plane of the two positioning antennas to determine whether the shopping cart is within the width of the boundary line that prohibits the cart from being pushed out. The controller compares the RSSI values ​​of the directional antennas on both sides of the first vertical plane of the first or second positioning antenna to determine which side of the boundary line the shopping cart is on, or compares the RSSI values ​​of the directional antennas on both sides of the first vertical plane of the first and second positioning antennas respectively, and determines which side of the boundary line the shopping cart is on based on the same comparison result. When the shopping cart is positioned outside the boundary line width, or based on positioning results at different times, it is determined that the shopping cart has moved from the inside to the outside of the boundary line width, and a locking command is sent to the shopping cart. Upon receiving the locking command, the shopping cart activates the braking mechanism to lock the shopping cart.

[0081] Alternatively, the base station may be configured with only one controller, to which all signal processing modules are connected.

[0082] Alternatively, the base station includes a primary base station and a secondary base station. The primary base station includes a first positioning antenna, a signal processing module with the same number of directional antennas as the primary positioning antenna, and a first controller, and optionally also includes a transmitting antenna. The secondary base station includes a second positioning antenna, a signal processing module with the same number of directional antennas as the second positioning antenna, and a second controller. The secondary base station communicates with the primary base station (via a wired or additionally configured communication module and antenna).

[0083] The second controller compares the RSSI values ​​of the directional antennas on both sides of the second vertical plane of the second positioning antenna and sends the comparison result to the first controller. Optionally, the second controller also compares the RSSI values ​​of the directional antennas on both sides of the first vertical plane of the second positioning antenna and sends the comparison result to the first controller. The first controller compares the RSSI values ​​of the directional antennas on both sides of the second vertical plane of the first positioning antenna and, in conjunction with the comparison result of the second controller for the second vertical plane, determines whether the shopping cart is located within the width range of the boundary line that prohibits shopping carts from being pushed out. The first controller compares the RSSI values ​​of the directional antennas on both sides of the first vertical plane of the first positioning antenna and, based on the comparison result, determines which side of the boundary line prohibiting shopping carts from being pushed out is located on, or, optionally, determines which side of the boundary line prohibiting shopping carts from being pushed out is located on, based on the same comparison result as the second controller's comparison result for the first vertical plane. When the shopping cart is positioned outside a boundary width that prevents the cart from being pushed out, or, based on positioning results at different times, it is determined that the shopping cart has moved from the inside to the outside of a boundary width that prevents the cart from being pushed out, the first controller generates a locking command and sends it to the shopping cart via a transmitting antenna (if a transmitting antenna is configured) or one of the directional antennas of the first positioning antenna (if no transmitting antenna is configured).

[0084] It can be conceivable that: installing the aforementioned shopping cart control system based on dual vertical plane comparison at the entrance and exit of a closed parking lot constitutes a shopping cart anti-theft system based on dual vertical plane comparison, which can effectively prevent shopping carts from being pushed out of the supermarket area from the entrance and exit of the closed parking lot; applying the aforementioned shopping cart control system based on dual vertical plane comparison to an open parking lot, dividing the parking lot boundary into several straight segments, and setting up a system for each segment, constitutes another shopping cart anti-theft system based on dual vertical plane comparison, which can effectively prevent shopping carts from being pushed out of the supermarket area from the boundary of the open parking lot; the aforementioned shopping cart control system based on dual vertical plane comparison... A shopping cart control system positioned at the boundary preventing unchecked shopping carts from being pushed out, with "unchecked shopping cart" as a prerequisite for issuing a locking command, constitutes a merchandise anti-theft system based on dual vertical plane comparison. This effectively prevents unchecked merchandise from being stolen by pushing out the shopping cart. Alternatively, placing this dual vertical plane comparison-based shopping cart control system at the entrance of the supermarket shopping area, with "the shopping cart moving from the inside to the outside of a boundary line preventing carts from being pushed out" as a condition for issuing a locking command, constitutes a dual vertical plane comparison-based shopping cart reverse-movement control system. This prevents customers from pushing shopping carts out of the shopping area entrance in the opposite direction.

[0085] The present invention also discloses a positioning antenna based on a four-quadrant distribution structure, comprising multiple identical directional antennas. The directional antennas are circumferentially distributed at the same horizontal height with the intersection of two mutually perpendicular vertical planes as the central axis. The radiation direction of each directional antenna is radially outward with the central axis as the center. The vertical projection of the two vertical planes divides the horizontal plane into four quadrants, and each quadrant has at least one directional antenna.

[0086] Preferably, the directional antenna comprises four groups, each located in one of the four quadrants. The four groups of antennas form a 90-degree rotationally symmetrical structure with the intersection of two vertical planes as the central axis.

[0087] Furthermore, the four antennas form a centrally symmetrical structure with the intersection of the two vertical planes as the central axis.

[0088] Furthermore, the four antennas form a ring array structure with the intersection of the two vertical planes as the central axis.

[0089] Based on the aforementioned four-quadrant distribution structure of the positioning antenna, this invention further claims a positioning method based on vector operations for determining the relative position of a target object with respect to two mutually perpendicular target vertical planes. This method uses the target object as the signal transmitter, with the intersection of the two target vertical planes as the central axis, and arranges multiple directional antennas circumferentially. In each of the four right-angle regions formed by the two target vertical planes, at least one directional antenna is distributed. The RSSI value of the same signal received from the target object by each directional antenna is used as the magnitude of the vector, and the angle of the directional antenna is used as the direction of the vector to obtain the detection vector of that directional antenna. The detection vectors of each directional antenna are added together to obtain a positioning vector. The quadrant in which the direction of this positioning vector lies determines which right-angle region the target object is located in.

[0090] Based on the aforementioned vector-based positioning method, this invention discloses a vector-based positioning system for locating an object crossing a target boundary. The system includes a positioning device and the object being located. The object is equipped with a signal transmitter. The positioning device includes two positioning antennas with a four-quadrant distribution structure (described above) positioned at both ends of the target boundary, several signal processing modules, and a controller for vector operation judgment. Each directional antenna of the two positioning antennas is connected to a signal processing module. Each signal processing module calculates and outputs the RSSI value of the signal received by its connected directional antenna. The first vertical plane of the first positioning antenna and the second positioning antenna are both aligned with the target boundary. The controller uses the RSSI value of the directional antenna as the magnitude of the vector and the angle of the directional antenna as the direction of the vector to generate a detection vector for one directional antenna. The controller adds the detection vectors of all directional antennas of a given positioning antenna to obtain the positioning vector of that antenna. The controller combines the directions of the positioning vectors from the two antennas to determine whether the object being located is within the width of the target boundary and, if so, on which side of the target boundary it is located.

[0091] The aforementioned positioning system based on vector operations can be used for shopping cart reverse movement control, shopping cart anti-theft, or product anti-theft.

[0092] When used for shopping cart reverse movement control, two positioning antennas are set on both sides of the prohibited reverse movement channel. The second positioning antenna is set to be located on the positive half-axis of the X-axis of the first positioning antenna. The first quadrant of the first positioning antenna and the second quadrant of the second positioning antenna are used as the locking zone, and the fourth quadrant of the first positioning antenna and the third quadrant of the second positioning antenna are used as the unlocking zone. When the shopping cart moves from the unlocking zone to the locking zone without passing through other zones, a locking command is sent to the shopping cart. The shopping cart receives and responds to the locking command, and activates the braking mechanism to lock the shopping cart.

[0093] When used for shopping cart anti-theft, positioning antennas are placed on both sides of the parking lot entrance and exit. A second positioning antenna is positioned on the positive X-axis of the first positioning antenna. The area where the first quadrant of the first positioning antenna coincides with the second quadrant of the second positioning antenna is designated as the locking zone, and the area where the fourth quadrant of the first positioning antenna coincides with the third quadrant of the second positioning antenna is designated as the unlocking zone. When the shopping cart is in the locking zone, a locking command is sent to the cart. The cart receives and responds to the locking command, activating the braking mechanism to lock the cart. Furthermore, when the shopping cart is in the unlocking zone, an unlocking command is sent to the cart. The cart receives and responds to the unlocking command, activating the braking mechanism to unlock the cart.

[0094] When used for anti-theft of goods, the positioning antennas are placed on both sides of the supermarket entrance, and the control condition is that the shopping cart has not been checked out. The control method can be the aforementioned reverse control method or the shopping cart anti-theft control method.

[0095] This invention further claims a shopping cart control method based on vector operations, using the aforementioned vector-based positioning system for supermarket shopping cart control. The method uses the shopping cart as the object to be positioned, equips it with a braking mechanism to restrict its movement, and provides both command receiving and positioning signal sending capabilities. Two positioning antennas with a four-quadrant distribution structure are positioned at either end of a boundary line (e.g., a parking lot entrance / exit boundary) to receive positioning signals from the shopping cart. The first vertical planes of the two positioning antennas correspond to the boundary line. The RSSI value of the directional antenna is used as the magnitude of the vector, and the angle of the directional antenna is used as the direction of the vector to obtain the detection vector of one directional antenna. The positioning vector of the positioning antenna is obtained by adding the detection vectors of all the directional antennas of the positioning antenna. The directions of the positioning vectors of the two positioning antennas are combined to determine whether the shopping cart is within the width of the boundary line prohibiting cart movement, and which side of the boundary line it is on. When the shopping cart is positioned outside a boundary that prevents it from being pushed out, or, based on positioning results at different times, it is determined that the shopping cart has moved from the inside to the outside of a boundary that prevents it from being pushed out, a locking command is sent to the shopping cart. Upon receiving the locking command, the shopping cart activates its braking mechanism to lock the cart.

[0096] Furthermore, the positioning signal sent by the shopping cart includes the status information of the shopping cart being locked or unlocked. When the shopping cart is located inside a boundary line that prevents the shopping cart from being pushed out and is in a locked state, an unlock command is sent to the shopping cart. After receiving the unlock command, the shopping cart activates the braking mechanism to unlock the shopping cart.

[0097] Based on the aforementioned shopping cart control method based on vector operations, this invention further claims a shopping cart control system based on vector operations, comprising a shopping cart as the object to be located, and a base station for locating and controlling the shopping cart. The shopping cart is equipped with a braking mechanism to limit its movement, and a transceiver for sending positioning signals and receiving control commands. The base station is equipped with a positioning antenna for receiving positioning signals, a signal processing module having the same number of directional antennas as the positioning antenna, and a controller for determining positioning and generating control commands. Optionally, the base station is also equipped with a transmitting antenna for sending control commands (if no transmitting antenna is configured, control commands can also be sent through the positioning antenna).

[0098] The positioning antenna is the aforementioned positioning antenna based on a four-quadrant distribution structure. The positioning antenna includes a first positioning antenna and a second positioning antenna respectively positioned at both ends of a boundary line prohibiting shopping carts from being pushed out. The first vertical planes of the first and second positioning antennas overlap and correspond to the boundary line prohibiting shopping carts from being pushed out. Each directional antenna in the positioning antenna is connected to a signal processing module. Each signal processing module calculates and outputs the RSSI value of the positioning signal received by its connected directional antenna. Each signal processing module is connected to a controller. The controller uses the RSSI value of the directional antenna as the magnitude of the vector and the angle of the directional antenna as the direction of the vector to generate a detection vector for the directional antenna. The controller adds the detection vectors of all directional antennas of a positioning antenna to obtain the positioning vector of that positioning antenna. The controller combines the directions of the positioning vectors of the two positioning antennas to determine whether the shopping cart is located within the width of the boundary line prohibiting shopping carts from being pushed out, and on which side of the boundary line it is located on. When the shopping cart is located outside a boundary that prevents it from being pushed out, or when the location results at different times indicate that the shopping cart has moved from the inside to the outside of a boundary that prevents it from being pushed out, the base station sends a locking command to the shopping cart. After receiving the locking command, the shopping cart activates its braking mechanism to lock the cart.

[0099] Alternatively, the base station may be configured with only one controller, to which all signal processing modules are connected.

[0100] Alternatively, the base station includes a primary base station and a secondary base station. The primary base station includes a first positioning antenna, a signal processing module with the same number of directional antennas as the first positioning antenna, and a first controller, and optionally also includes a transmitting antenna. The secondary base station includes a second positioning antenna, a signal processing module with the same number of directional antennas as the second positioning antenna, and a second controller. The secondary base station (optionally via a wired or additionally configured communication module and antenna) communicates with the primary base station.

[0101] The second controller adds the detection vectors of all directional antennas of the second positioning antenna to obtain the positioning vector of the second positioning antenna, and sends the direction of the positioning vector (an angle value between 0 and 360 degrees) to the first controller. The first controller adds the detection vectors of all directional antennas of the first positioning antenna to obtain the positioning vector of the first positioning antenna. Combining the directions of the positioning vectors of the first and second positioning antennas, the first controller determines whether the shopping cart is within the width of the no-cart-out boundary and, if so, which side of the no-cart-out boundary it is located on. When the shopping cart is positioned outside the no-cart-out boundary, or, based on positioning results at different times, it is determined that the shopping cart has moved from the inside to the outside of the no-cart-out boundary, the first controller generates a locking command and sends it to the shopping cart via a transmitting antenna (if a transmitting antenna is configured) or one of the directional antennas of the first positioning antenna (if no transmitting antenna is configured).

[0102] It is conceivable that: Installing the aforementioned vector-based shopping cart control system at the entrance and exit of a closed parking lot constitutes a vector-based shopping cart anti-theft system, effectively preventing shopping carts from being pushed out of the supermarket area from the entrance / exit of the closed parking lot; applying the same vector-based shopping cart control system to an open parking lot, dividing the parking lot boundary into several straight segments, and installing one system for each segment, constitutes another vector-based shopping cart anti-theft system, effectively preventing shopping carts from being pushed out of the supermarket area from the boundary of the open parking lot; the aforementioned vector-based... A shopping cart control system positioned at the boundary preventing unchecked shopping carts from being pushed out, with "unchecked shopping cart" as a prerequisite for issuing a locking command, constitutes a vector-based anti-theft system that can effectively prevent unchecked goods from being stolen by pushing the shopping cart out. Alternatively, placing this vector-based shopping cart control system at the entrance of the supermarket shopping area, with "the shopping cart moving from the inside to the outside of a boundary line preventing carts from being pushed out" as a condition for issuing a locking command, constitutes a vector-based reverse-movement control system that can prevent customers from pushing their shopping carts out of the shopping area entrance in the opposite direction.

[0103] The beneficial effects of this invention are as follows: Compared with the existing technology's locking area generation principle, the positioning principle of this invention can not only form a linear locking interface (the measured line width can be controlled within 0.5m), but also directly distinguish the movement direction of the located object from the inside to the outside or from the outside to the inside. More importantly, signal strength is very easily affected by environmental interference. Using an absolute threshold as a judgment condition, the effective coverage area of ​​the antenna (the area greater than the threshold) will change under different weather conditions, whether there are pedestrians walking, or whether there are objects blocking the signal, resulting in poor stability. Under good conditions, an antenna that can cover the entire target area may no longer be able to cover the entire target area under poor conditions, leading to loopholes in anti-theft measures. The two-antenna RSSI value comparison method proposed in this invention addresses the issue that since the two antennas receive signals from the same source at the same location and at the same time, the influence of external factors on signal transmission exists for both antennas. That is, the RSSI values ​​of the two antennas increase or decrease under environmental influences, and this same increase or decrease is eliminated when calculating the difference. Therefore, this method can effectively solve the problem of environmental influence in existing technologies. Attached Figure Description

[0104] Figure 1 is a schematic diagram of a PCB directional antenna.

[0105] Figure 2 shows the horizontal orientation of the PCB directional antenna shown in Figure 1.

[0106] Figure 3 is a schematic diagram of the effective horizontal coverage area of ​​the PCB directional antenna shown in Figure 1.

[0107] Figure 4 is a schematic diagram of the first type of positioning antenna unit.

[0108] Figure 5 is a schematic diagram of the second type of positioning antenna unit.

[0109] Figure 6 is a schematic diagram of the third type of positioning antenna unit.

[0110] Figure 7 is a schematic diagram of the first type of positioning antenna based on a single vertical plane symmetrical structure.

[0111] Figure 8 is a schematic diagram of the second type of positioning antenna based on a single vertical plane symmetric structure.

[0112] Figure 9 is a schematic diagram of the third type of positioning antenna based on a single vertical plane symmetric structure.

[0113] Figure 10 is a schematic diagram of the fourth type of positioning antenna based on a single vertical plane symmetric structure.

[0114] Figure 11 is a schematic diagram of the fifth type of positioning antenna based on a single vertical plane symmetric structure.

[0115] Figure 12 is a schematic diagram of the sixth type of positioning antenna based on a single vertical plane symmetric structure.

[0116] Figure 13 is a schematic diagram of the seventh type of positioning antenna based on a single vertical plane symmetric structure.

[0117] Figure 14 is a schematic diagram of the eighth type of positioning antenna based on a single vertical plane symmetric structure.

[0118] Figure 15 is a schematic diagram of the working principle of a positioning antenna based on a dual vertical symmetric structure.

[0119] Figure 16 is a schematic diagram of the first type of positioning antenna based on a dual vertical symmetric structure.

[0120] Figure 17 is a schematic diagram of the second type of positioning antenna based on a dual vertical symmetric structure.

[0121] Figure 18 is a schematic diagram of the third type of positioning antenna based on a dual vertical symmetric structure.

[0122] Figure 19 is a schematic diagram of the fourth type of positioning antenna based on a dual vertical symmetric structure.

[0123] Figure 20 is a schematic diagram of the fifth type of positioning antenna based on a dual vertical symmetric structure.

[0124] Figure 21 is a schematic diagram of the sixth type of positioning antenna based on a dual vertical symmetric structure.

[0125] Figure 22 is a schematic diagram of the seventh type of positioning antenna based on a dual vertical symmetric structure.

[0126] Figure 23 is a schematic diagram of the first type of positioning antenna based on a four-quadrant distribution structure.

[0127] Figure 24 is a schematic diagram of the second type of positioning antenna based on a four-quadrant distribution structure.

[0128] Figure 25 is a schematic diagram of the third type of positioning antenna based on a four-quadrant distribution structure.

[0129] Figure 26 is a schematic diagram of the fourth type of positioning antenna based on a four-quadrant distribution structure.

[0130] Figure 27 is a schematic diagram of the fifth type of positioning antenna based on a four-quadrant distribution structure.

[0131] Figure 28 is a schematic diagram of the effective coverage area of ​​a directional antenna.

[0132] Figure 29 is a schematic diagram of the effective coverage area of ​​a positioning antenna based on a dual vertical symmetric structure or a positioning antenna based on a four-quadrant distribution structure.

[0133] Figure 30 is a schematic diagram of the first positioning antenna setup based on a single vertical plane symmetric structure.

[0134] Figure 31 is a schematic diagram of the second type of positioning antenna setup based on a single vertical plane symmetric structure.

[0135] Figure 32 is a schematic diagram of the third type of positioning antenna setup based on a single vertical plane symmetric structure.

[0136] Figure 33 is a schematic diagram of the installation method of a positioning antenna based on a single vertical plane symmetry structure for use in an open parking lot.

[0137] Figure 34 is a schematic diagram of the actual application of positioning antennas based on a dual vertical symmetric structure or a four-quadrant distribution structure.

[0138] Figure 35 is a schematic diagram of the installation method of positioning antennas based on a dual vertical symmetric structure or a four-quadrant distribution structure for use in an open parking lot. Detailed Implementation

[0139] The technical solutions claimed in this invention will be further described below with reference to the accompanying drawings and examples.

[0140] Figure 1 shows a PCB directional antenna 101. The PCB is rectangular, and the antenna radiation direction is along the length of the PCB. The PCB is placed vertically for use. The horizontal radiation pattern of the antenna is shown in Figure 2. Its beamwidth 102 is oval, and the beamwidth is 70 degrees. In use, the shape of the effective horizontal coverage area 103 of the antenna is consistent with the shape of the beamwidth, and the effective horizontal coverage area 103 is symmetrical along the centerline, as shown in Figure 3.

[0141] Referring to Figure 4, two directional antennas as shown in Figure 1 are symmetrically arranged along a vertical plane (shown by the center line) to form a positioning antenna unit 104 (1) as described in this invention. This unit can be directly used as a positioning antenna based on a single vertical plane symmetrical structure to locate which side of the target vertical plane the object is located on. In this example, the angle between the two directional antennas is 70 degrees, which is exactly equal to the beamwidth of the directional antenna. As can be seen in the figure, the effective horizontal coverage area 103 of the two directional antennas overlaps at the center line representing the vertical plane.

[0142] Referring to Figure 5, this example also uses two directional antennas as shown in Figure 1, symmetrically arranged along a vertical plane (shown by the center line) to form a positioning antenna unit 104 (2) as described in this invention. In this example, the included angle between the two directional antennas is 90 degrees, which is greater than the beamwidth of the directional antennas. However, as can be seen in the figure, the effective coverage area 103 of the horizontal plane of the two directional antennas still overlaps to a certain extent at the center line used to represent the vertical plane, but the effective operating distance of the positioning antenna unit when positioning is shorter than that shown in the example in Figure 4.

[0143] Figure 6 shows another example of the positioning antenna unit of the present invention. The directional antenna used in this example has a narrower beamwidth, and the corresponding effective coverage area is also narrower and longer. The directional antenna unit constructed in this way has a longer effective range when used to locate the directional object.

[0144] Figure 7-14 shows several examples of positioning antennas based on a single vertical plane symmetric structure.

[0145] The positioning antenna shown in Figure 7 consists of four directional antennas. The first directional antenna 210 and the second directional antenna 211 form the first positioning antenna unit 201, with their operating direction pointing upwards along the centerline d1. The third directional antenna 212 and the fourth directional antenna 213 form the second positioning antenna unit 202, with their operating direction pointing upwards along the centerline d1. The entire positioning antenna operates with its operating direction pointing upwards along the centerline d1. This can be used to determine whether the object being positioned above the positioning antenna is located to the left or right of the target's vertical plane (corresponding to the centerline).

[0146] The positioning antenna shown in Figure 8 also consists of four directional antennas. The first directional antenna 215 and the second directional antenna 216 form the first positioning antenna unit 203, with its operating direction pointing upwards along the centerline d1. The third directional antenna 217 and the fourth directional antenna 218 form the second positioning antenna unit 204, with its operating direction pointing downwards along the centerline d1. The entire positioning antenna operates both upwards and downwards along the centerline d1. This can be used to determine whether the object being positioned above or below the positioning antenna is located to the left or right of the target's vertical plane (corresponding to the centerline).

[0147] The positioning antenna shown in Figure 9 consists of six directional antennas. The first directional antenna 219 and the second directional antenna 220 form the first positioning antenna unit 205, with their operating direction upwards along the centerline d1. The third directional antenna 221 and the fourth directional antenna 222 are symmetrical along the centerline d1 and are used for auxiliary judgment. The fifth directional antenna 223 and the sixth directional antenna 224 form the second positioning antenna unit 206, with their operating direction downwards along the centerline d1. The entire positioning antenna operates both upwards and downwards along the centerline d1. This can be used to determine whether the object being positioned above or below the positioning antenna is located to the left or right of the target's vertical plane (corresponding to the centerline). In this example, theoretically, the third directional antenna 221 and the fourth directional antenna 222 cannot simultaneously receive the positioning signal emitted by the object being positioned. When one of them receives the positioning signal, it can be basically determined that the object being positioned is located on the side of that directional antenna. By adding the RSSI values ​​of the third directional antenna 221 and the fourth directional antenna 222 to the comparison, misjudgments that may occur when using only the first directional antenna 219, the second directional antenna 220, the fifth directional antenna 223, and the sixth directional antenna 224 can be effectively corrected.

[0148] The positioning antenna shown in Figure 10 also consists of six directional antennas. The first directional antenna 225 and the second directional antenna 226 form the first positioning antenna unit 207, with their operating direction pointing upwards along the centerline d1. The third directional antenna 227 and the fourth directional antenna 228 form the second positioning antenna unit 208, with their operating direction pointing upwards along the centerline d1, and their included angle being greater than the included angle between the first directional antenna 225 and the second directional antenna 226. The fifth directional antenna 229 and the sixth directional antenna 230 form the third positioning antenna unit 209, with their operating direction pointing upwards along the centerline d1, and their included angle being greater than the included angle between the third directional antenna 227 and the fourth directional antenna 228. Combining three positioning antenna units of different sizes and with different included angles allows the positioning effects of each positioning antenna unit to complement each other.

[0149] The positioning antenna shown in Figure 11 consists of eight directional antennas, including four positioning antenna elements. The first directional antenna 231 and the second directional antenna 232 constitute the first positioning antenna element 250, with its direction of action pointing upwards along the centerline d1. The third directional antenna 233 and the fourth directional antenna 234 constitute the second positioning antenna element 251, with its direction of action pointing upwards along the centerline d1, and the angle between them being greater than the angle between the first directional antenna 231 and the second directional antenna 232. The fifth directional antenna 235 and the sixth directional antenna 236 constitute the third positioning antenna element 252, with its direction of action pointing downwards along the centerline d1, and the angle between them being equal to... The angle between the third directional antenna 233 and the fourth directional antenna 234, and the seventh directional antenna 237 and the eighth directional antenna 238 constitute the fourth positioning antenna unit 253. The direction of action is downward along the centerline d1, and the angle between them is equal to the angle between the first directional antenna 231 and the second directional antenna 232. The two upper positioning antenna units have the direction of action upward along the centerline, use directional antennas of different sizes, and have different angles, so their positioning effects complement each other. The two lower positioning antenna units have the direction of action downward along the centerline, use directional antennas of different sizes, and have different angles, so their positioning effects complement each other.

[0150] The positioning antenna shown in Figure 12 consists of four directional antennas and one omnidirectional antenna. The first directional antenna 239 and the second directional antenna 240 form the first positioning antenna element 254, with their operating direction pointing upwards along the centerline d1. The third directional antenna 242 and the fourth directional antenna 243 form the second positioning antenna element 255, with their operating direction pointing downwards along the centerline d1. The omnidirectional antenna 241 is located at the center of the positioning antenna structure and can be used to determine whether the object being located has entered the area to be located based on the RSSI value.

[0151] The positioning antenna shown in Figure 13 consists of six directional antennas. The first directional antenna 244 and the second directional antenna 245 form the first positioning antenna unit 256, with their operating direction pointing upwards along the centerline d1. The third directional antenna 246 and the fourth directional antenna 247 form the second positioning antenna unit 257, with their operating direction pointing downwards along the centerline d1. The fifth directional antenna 248 and the sixth directional antenna 249 are positioned on the centerline d1 (vertical plane). The fifth directional antenna 248 has its operating direction pointing upwards along the centerline d1, and the sixth directional antenna 249 has its operating direction pointing downwards along the centerline d1. These antennas are used to determine whether the object being positioned has entered the area to be positioned from above or below. The entire positioning antenna operates with its operating direction pointing upwards and downwards along the centerline d1.

[0152] The positioning antenna shown in Figure 14 consists of four directional antennas. The first directional antenna 258 and the second directional antenna 259 are symmetrical along the vertical plane d1, forming the first positioning antenna element 262. The third directional antenna 260 and the fourth directional antenna 261 are symmetrical along the vertical plane d1, forming the second positioning antenna element 263. The first positioning antenna element 262 and the second positioning antenna element 263 use the same directional antennas and are set at the same angle, overlapping in the vertical direction. In use, the RSSI values ​​of the two antennas are compared separately. The positioning result is obtained if the comparison results of the two positioning antenna elements are the same, which can effectively reduce false positioning. Figures 15-22 show several examples of positioning antennas based on a dual-vertical-plane symmetrical structure.

[0153] The positioning antenna shown in Figure 15 consists of four directional antennas, evenly distributed along two mutually perpendicular vertical planes. It is a positioning antenna based on a single-plane symmetric structure, and also constitutes a positioning antenna based on a double-plane symmetric structure. In this positioning antenna, the four directional antennas form a symmetrical result relative to either vertical plane; that is, the overall structure is centrally symmetric with the intersection of the two vertical planes (the intersection of the two medians shown in the figure) as the central axis (it coincides with the original structure after rotating 180 degrees around the central axis). As can be seen in the figure, every two adjacent directional antennas constitute a positioning antenna unit of this invention. Specifically, the first and second directional antennas form a positioning antenna unit of this invention with the first vertical plane d1 as the symmetric plane; the second and third directional antennas form a positioning antenna unit of this invention with the second vertical plane d2 as the symmetric plane; the third and fourth directional antennas form a positioning antenna unit of this invention with the first vertical plane d1 as the symmetric plane; and the fourth and first directional antennas form a positioning antenna unit of this invention with the second vertical plane d2 as the symmetric plane. The first vertical plane d1 and the second vertical plane d2 are perpendicular to each other and divide the area into four right-angled regions.

[0154] The positioning antenna shown in Figure 16 consists of eight directional antennas. The first directional antenna 301 and the second directional antenna 302 form a positioning antenna unit with the first vertical plane d1 as the plane of symmetry; the third directional antenna 303 and the fourth directional antenna 304 form a positioning antenna unit with the first vertical plane d1 as the plane of symmetry; the fifth directional antenna 305 and the sixth directional antenna 306 form a positioning antenna unit with the first vertical plane d1 as the plane of symmetry; the seventh directional antenna 307 and the eighth directional antenna 308 form a positioning antenna unit with the first vertical plane d1 as the plane of symmetry; the fourth directional antenna 304 and the sixth directional antenna 306 form a positioning antenna unit with the second vertical plane d2 as the plane of symmetry; and the third directional antenna 303 and the fifth directional antenna 305 form a positioning antenna unit with the second vertical plane d2 as the plane of symmetry. This can be used to determine which right-angle region the object being located is in. Combining two positioning antenna units of different sizes allows the positioning effects of each antenna unit to complement each other.

[0155] The positioning antenna shown in Figure 17 consists of six directional antennas. The first directional antenna 309 and the second directional antenna 310 form a positioning antenna unit with the first vertical plane d1 as their plane of symmetry. The third directional antenna 311 and the fourth directional antenna 312 are symmetrical along the centerline d1 and are used to assist in the determination. The fifth directional antenna 313 and the sixth directional antenna 314 form a positioning antenna unit with the first vertical plane d1 as their plane of symmetry. The first directional antenna 309 and the fifth directional antenna 313 form a positioning antenna unit with the second vertical plane d2 as their plane of symmetry. The second directional antenna 310 and the sixth directional antenna 314 form a positioning antenna unit with the second vertical plane d2 as their plane of symmetry. This can be used to determine which right-angle region the object being positioned is located in. In this example, theoretically, the third directional antenna 311 and the fourth directional antenna 312 cannot simultaneously receive the positioning signal emitted by the object being positioned. When one of them receives the positioning signal, it can be basically determined that the object being positioned is located on the side of that directional antenna. By adding the RSSI values ​​of the third directional antenna 311 and the fourth directional antenna 312 to the comparison, misjudgments that may occur when using only the first directional antenna 309, the second directional antenna 310, the fifth directional antenna 313, and the sixth directional antenna 314 can be effectively corrected.

[0156] The positioning antenna shown in Figure 18 consists of four directional antennas and one omnidirectional antenna. The first directional antenna 315 and the second directional antenna 316 form a positioning antenna unit with the first vertical plane d1 as the plane of symmetry; the third directional antenna 318 and the fourth directional antenna 319 form a positioning antenna unit with the first vertical plane d1 as the plane of symmetry; the first directional antenna 315 and the third directional antenna 318 form a positioning antenna unit with the second vertical plane d2 as the plane of symmetry; the second directional antenna 316 and the fourth directional antenna 319 form a positioning antenna unit with the second vertical plane d2 as the plane of symmetry; the omnidirectional antenna 317 is located at the center of the positioning antenna structure and can be used to determine whether the object being positioned has entered the area to be positioned based on the RSSI value.

[0157] The positioning antenna shown in Figure 19 consists of eight directional antennas. The first directional antenna 320 and the second directional antenna 322 form a positioning antenna unit with the first vertical plane d1 as the plane of symmetry; the second directional antenna 322 and the third directional antenna 324 form a positioning antenna unit with the first vertical plane d2 as the plane of symmetry; the third directional antenna 324 and the fourth directional antenna 326 form a positioning antenna unit with the first vertical plane d1 as the plane of symmetry; the fourth directional antenna 326 and the first directional antenna 320 form a positioning antenna unit with the first vertical plane d2 as the plane of symmetry; the fifth directional antenna 321 and the sixth directional antenna 325 are symmetrical along the centerline d2 and are used to assist in the judgment; the seventh directional antenna 327 and the eighth directional antenna 323 are symmetrical along the centerline d1 and are used to assist in the judgment, determining whether the object to be positioned has entered the area to be positioned. The first directional antenna 320, the second directional antenna 322, the third directional antenna 324, and the fourth directional antenna 326 are located on the same circumference; the fifth directional antenna 321, the sixth directional antenna 325, the seventh directional antenna 327, and the eighth directional antenna 323 are located on the same circumference.

[0158] The positioning antenna shown in Figure 20 consists of eight directional antennas and one omnidirectional antenna. The first directional antenna 329 and the second directional antenna 330 form a positioning antenna unit with the first vertical plane d1 as their plane of symmetry; the third directional antenna 331 and the fourth directional antenna 332 form a positioning antenna unit with the second vertical plane d2 as their plane of symmetry; the fifth directional antenna 333 and the sixth directional antenna 334 form a positioning antenna unit with the first vertical plane d1 as their plane of symmetry; the seventh directional antenna 335 and the eighth directional antenna 328 form a positioning antenna unit with the second vertical plane d2 as their plane of symmetry; the omnidirectional antenna 336 is located at the center of the positioning antenna structure and can be used to determine whether the object being positioned has entered the area to be positioned based on the RSSI value. The four positioning antenna units are symmetrical about the first vertical plane d1 and about the second vertical plane d2. The eight directional antennas are located on the same circumference.

[0159] The positioning antenna shown in Figure 21 consists of eight directional antennas. The first directional antenna 338 and the second directional antenna 339 form a positioning antenna unit with the first vertical plane d1 as its plane of symmetry; the third directional antenna 340 and the fourth directional antenna 341 form a positioning antenna unit with the second vertical plane d2 as its plane of symmetry; the fifth directional antenna 342 and the sixth directional antenna 343 form a positioning antenna unit with the first vertical plane d1 as its plane of symmetry; and the seventh directional antenna 344 and the eighth directional antenna 337 form a positioning antenna unit with the second vertical plane d2 as its plane of symmetry. The four positioning antenna units are symmetrical about the first vertical plane d1 and about the second vertical plane d2. Combining these four positioning antenna units of different sizes allows their positioning effects to complement each other.

[0160] The positioning antenna shown in Figure 22 consists of sixteen directional antennas. The first positioning antenna unit 345 is composed of two directional antennas with the first vertical plane d1 as the plane of symmetry. The second positioning antenna unit 346 is composed of two directional antennas with the first vertical plane d1 as the plane of symmetry. The included angle between the two directional antennas in the first positioning antenna unit 345 is smaller than the included angle between the two directional antennas in the second positioning antenna unit 346. The third positioning antenna unit 347 is composed of two directional antennas with the second vertical plane d2 as the plane of symmetry. The fourth positioning antenna unit 348 is composed of two directional antennas with the second vertical plane d2 as the plane of symmetry. The included angle between the two directional antennas in the third positioning antenna unit 347 is smaller than the included angle between the two directional antennas in the fourth positioning antenna unit 348. The fifth positioning antenna unit 349 consists of two directional antennas symmetrical about the first vertical plane d1. The sixth positioning antenna unit 350 consists of two directional antennas symmetrical about the first vertical plane d1. The included angle between the two directional antennas in the fifth positioning antenna unit 349 is greater than the included angle between the two directional antennas in the sixth positioning antenna unit 350. The seventh positioning antenna unit 351 consists of two directional antennas symmetrical about the second vertical plane d2. The eighth positioning antenna unit 352 consists of two directional antennas symmetrical about the second vertical plane d2. The included angle between the two directional antennas in the seventh positioning antenna unit 351 is smaller than the included angle between the two directional antennas in the eighth positioning antenna unit 352. All eight positioning antenna units are symmetrical about the first vertical plane d1 and about the second vertical plane d2. The eight positioning antenna units use directional antennas of different sizes and with different included angles, resulting in complementary positioning effects.

[0161] Figure 23-27 shows several examples of positioning antennas based on a four-quadrant distribution structure.

[0162] The positioning antenna shown in Figure 23 consists of four identical directional antennas. The first directional antenna 400, the second directional antenna 401, the third directional antenna 402, and the fourth directional antenna 403 are centrally positioned in the first, second, third, and fourth quadrants of the coordinate system at angles of 45°, 135°, 225°, and 315°, respectively. The four directional antennas are located on the same circumference, and their radiation direction is radially outward from the origin of the coordinate system.

[0163] The positioning antenna shown in Figure 24 also consists of four identical directional antennas. Unlike the example in Figure 23, the four antennas are not centrally located in the four quadrants. Instead, the first directional antenna 404, the second directional antenna 405, the third directional antenna 406, and the fourth directional antenna 407 are arranged in a 90° rotationally symmetrical structure in the first, second, third, and fourth quadrants of the coordinate system, respectively, with orientations of 30°, 120°, 210°, and 300°. The four directional antennas are located on the same circle, and their radiation direction is radially outward from the origin of the coordinate system.

[0164] The positioning antenna shown in Figure 25 consists of eight identical directional antennas. These eight antennas are not centrally located in the four quadrants, nor do they form a 90° rotationally symmetrical structure. The eight directional antennas are located on the same circle, and their radiation directions are all radially outward from the origin of the coordinate system.

[0165] The positioning antenna shown in Figure 26 consists of six identical directional antennas. The first directional antenna 408 and the second directional antenna 411 are centrally positioned in the first and third quadrants of the coordinate system, respectively, at 45° and 225° angles. The third directional antenna 409 and the fourth directional antenna 410 are evenly spaced in the second quadrant, with the third directional antenna 409 making a 30° angle with the Y-axis and the fourth directional antenna 410 making a 60° angle with the Y-axis. The fifth directional antenna 412 and the sixth directional antenna 413 are evenly spaced in the fourth quadrant, with the fifth directional antenna 412 making a 30° angle with the Y-axis and the sixth directional antenna 413 making a 60° angle with the Y-axis. These eight directional antennas form a 180° rotationally symmetrical structure, located on the same circumference, with their radiation direction radially outward from the origin of the coordinate system.

[0166] The positioning antenna shown in Figure 27 consists of eight identical directional antennas. These eight antennas are not centrally located in the four quadrants, but are evenly spaced in the coordinate system. The angle between any two adjacent directional antennas is 45°, and the eight antennas form a 45° rotationally symmetric structure. All eight antennas are located on the same circle, and their radiation direction is radially outward from the origin of the coordinate system. Each quadrant has two directional antennas, and the eight antennas are symmetric about the x-axis and y-axis. Figure 28 shows a directional antenna whose effective coverage area includes the area behind the antenna, but the gain in front is significantly greater than that in the sides and rear. Positioning antennas based on a dual-vertical-plane symmetric structure or a four-quadrant distribution structure, such as the positioning antenna shown in Figure 29, can locate the target when each directional antenna receives a positioning signal.

[0167] Figures 30-32 are schematic diagrams illustrating several configuration methods of the positioning antenna in practical applications of the shopping cart control system based on single vertical plane symmetry according to the present invention. The entrance / exit 510 shown in the figures can be the entrance / exit of a closed parking lot, the entrance of a supermarket, or the entrance to a shopping area, etc. Taking a positioning antenna based on a single vertical plane symmetry structure composed of a single positioning antenna unit as an example, there are three possible configuration methods.

[0168] The first setup method is to set up a positioning antenna 500 based on a single vertical plane symmetrical structure at one end of the entrance / exit 510. The positioning antenna 500 is directed towards the other end, and the effective range of the positioning antenna 500 covers the width of the entrance / exit 510, as shown in Figure 30.

[0169] The second setup is as follows: At each end of the entrance / exit 510, a positioning antenna 501 based on a single vertical plane symmetrical structure is set. The two positioning antennas 501 are set with their operating directions opposite each other. The sum of the effective operating distances of the two positioning antennas 501 covers the width of the boundary line that prohibits the shopping cart from being pushed out, as shown in Figure 31.

[0170] The third setting method: Set up a positioning antenna 502 based on a single vertical plane symmetrical structure at both ends of the entrance / exit 510. The two positioning antennas 502 are set with their working directions opposite each other. The effective working distance of each positioning antenna 502 covers the width of the boundary line that prohibits shopping carts from being pushed out, as shown in Figure 32.

[0171] Based on this third setting method, the shopping cart can be locked or unlocked by using the same positioning result from both positioning antennas as the final positioning result.

[0172] Figure 33 is a schematic diagram of one arrangement of the positioning antennas in the shopping cart anti-theft system based on single vertical plane symmetry of the present invention for use in an open parking lot. In this example, the parking lot 503 is rectangular, supported by a supermarket building 504, and the boundary of the parking lot is a semi-enclosed structure with three sides. A unidirectional positioning antenna 501 based on a single vertical plane symmetry structure is set at the two ends of the boundary, with its direction of action pointing downwards along the side boundary. Two unidirectional positioning antennas 501 based on a single vertical plane symmetry structure are set at the two corners of the boundary, with one positioning antenna's direction of action pointing upwards along the side boundary and the other positioning antenna's direction of action pointing towards the other corner along the bottom boundary. A bidirectional positioning antenna 501 based on a single vertical plane symmetry structure is set in the middle of the side boundary and the bottom boundary, with its direction of action coinciding with the boundary.

[0173] Figure 34 is a schematic diagram of the positioning antenna configuration in practical application of the shopping cart control system based on dual vertical plane comparison or the shopping cart control system based on vector operation of the present invention. The entrance / exit 510 shown in the figure can be the entrance / exit of a closed parking lot, the entrance of a supermarket, or the entrance to a shopping area, etc. In this example, a first positioning antenna 505 and a second positioning antenna 506 are respectively set at both ends of the entrance / exit 510. The first vertical plane d1 of the first positioning antenna 505 and the second positioning antenna 506 overlaps and corresponds to the boundary line set at the entrance / exit 510 that prohibits the cart from exiting.

[0174] Figure 35 is a schematic diagram of one arrangement of the positioning antenna when the shopping cart control system based on dual vertical plane comparison or the shopping cart control system based on vector operation of the present invention is used for anti-theft of shopping carts in an open parking lot. The parking lot boundary is divided into several straight segments, and a first positioning antenna 507 and a second positioning antenna 508 are respectively set at both ends of each straight segment. Two connected straight segments share one positioning antenna.

Claims

1. A symmetrical positioning antenna unit, comprising two identical directional antennas arranged together with different orientations, the two directional antennas being symmetrically arranged along a straight plane, and the included angle (in the direction of maximum radiation) of the two directional antennas satisfying that the effective horizontal coverage areas of the two directional antennas partially overlap.

2. A positioning antenna based on a single vertical plane symmetrical structure, comprising at least one pair of directional antennas arranged together, wherein the two directional antennas in each pair are identical and symmetrically arranged along the same vertical plane, and the effective horizontal coverage areas of the two directional antennas in at least one pair partially overlap.

3. The position antenna based on single vertical plane symmetry structure according to claim 2, characterized in that, This includes multiple pairs of directional antennas set together.

4. The position antenna based on single vertical plane symmetry structure according to claim 3, characterized in that, The effective horizontal coverage areas of the two directional antennas in each pair of positioning antennas partially overlap.

5. A positioning comparison method applicable to the positioning antenna based on a single vertical plane symmetrical structure as described in claim 4, wherein the sum of the RSSI values ​​of all directional antennas on one side of the vertical plane of the positioning antenna is compared with the sum of the RSSI values ​​of all directional antennas on the other side, or the RSSI values ​​of each pair of directional antennas are compared separately, and then the final comparison result is obtained based on the individual comparison results of each pair of directional antennas.

6. A positioning method based on single vertical plane comparison, used to determine the relative position of the object to be positioned relative to a target vertical plane. The method uses the object to be positioned as the signal transmitting end, and sets up directional antennas in pairs along the target vertical plane as receiving ends. The two directional antennas in the pair are identical and symmetrically arranged along the target vertical plane. The horizontal angle between the two directional antennas in the pair is set so that the effective horizontal coverage areas of at least two of the directional antennas in the pair partially overlap. By comparing the RSSI values ​​of the same signal emitted by the object to be positioned received by the directional antennas on both sides of the target vertical plane, it is determined which side of the target vertical plane the object to be positioned is located on.

7. The positioning method based on single vertical plane comparison according to claim 6, characterized in that, Two identical directional antennas are symmetrically set along the vertical plane of the target. The horizontal angle between the two directional antennas is set so that the effective coverage areas of the horizontal planes of the two directional antennas partially overlap. By comparing the RSSI values ​​of the same signal emitted by the target object received by the two directional antennas, it is determined which side of the vertical plane of the target object is located on. The side of the directional antenna with the larger RSSI value is the side where the target object is currently located.

8. The positioning method based on single vertical plane comparison according to claim 6, characterized in that, At least two pairs of positioning antennas are symmetrically set along the vertical plane of the target. The two positioning antennas in each pair are the same and symmetrical with each other along the vertical plane of the target. The horizontal angle of each pair of directional antennas is set so that the effective coverage areas of the horizontal plane of at least two of the directional antennas in the pair partially overlap. By comparing the sum of the RSSI values ​​of the same signal emitted by the target object received by the directional antennas on both sides of the vertical plane of the target, it is determined which side of the vertical plane of the target is the target object located on. The side of the directional antenna with the larger sum of RSSI values ​​is the side where the target object is currently located.

9. The positioning method based on single vertical plane comparison according to claim 6, characterized in that, At least two pairs of positioning antennas are symmetrically set along the vertical plane of the target. The two positioning antennas in each pair are identical and symmetrical with each other along the vertical plane of the target. The horizontal angle between each pair of directional antennas is set so that the effective horizontal coverage areas of the two directional antennas in each pair partially overlap. The RSSI values ​​of the same signal emitted by the target object received by the two directional antennas in each pair are compared. The comparison result that is completely consistent or the majority is taken as the final comparison result. The side of the target vertical plane where the target object is located is determined. The side of the directional antenna with the larger RSSI value in the final comparison result is the side where the target object is currently located.

10. A positioning system based on single vertical plane comparison, comprising a positioning device and a target object, wherein the target object is equipped with a signal transmitter, the positioning device comprising a positioning antenna disposed on the target vertical plane and a receiving processing control unit configured for the positioning antenna, the positioning antenna comprising at least one pair of directional antennas, two of the directional antennas in each pair being identical and symmetrically arranged along the target vertical plane, the effective horizontal coverage areas of the two directional antennas in the at least one pair of directional antennas partially overlapping, the receiving processing control unit comprising a signal processing module equal in number to the directional antennas and a controller for positioning determination, each directional antenna being connected to a signal processing module, each signal processing module being connected to the controller, each signal processing module calculating and outputting the RSSI value of the signal received by the connected directional antenna, the controller comparing the RSSI values ​​of the same signal emitted by the target object received by the directional antennas on both sides of the target vertical plane, and determining which side of the target vertical plane the target object is located on based on the comparison result.

11. The positioning system based on single vertical plane comparison according to claim 10, characterized in that, The positioning antenna consists of only one pair of directional antennas. The controller compares the RSSI values ​​of the same signal emitted by the object being located, received by the two directional antennas in the pair, and determines the side where the directional antenna with the larger RSSI value is located as the current location of the object being located.

12. The positioning system based on single vertical plane comparison according to claim 10, characterized in that, The positioning antenna includes multiple pairs of directional antennas, with at least two of the directional antennas having partially overlapping horizontal effective coverage areas. The controller compares the sum of the RSSI values ​​of the signals received by the directional antennas on one side of the horizontal plane with the sum of the RSSI values ​​of the signals received by the directional antennas on the other side of the horizontal plane. The side where the sum of the RSSI values ​​of the directional antennas is larger is determined to be the current location of the object being located.

13. The positioning system based on single vertical plane comparison according to claim 10, characterized in that, The positioning antenna includes multiple pairs of directional antennas. The effective horizontal coverage areas of two directional antennas in each pair partially overlap. The controller compares the RSSI values ​​of the same signal emitted by the object being located, received by the two directional antennas in each pair. When the RSSI value of one side of the directional antenna is greater than the RSSI value of the symmetrical directional antenna, that side is determined to be the side where the object being located is currently located.

14. A shopping cart control method based on single vertical plane comparison, wherein the shopping cart is the object to be positioned, a braking mechanism is configured on the shopping cart to restrict its movement, and the shopping cart is also configured to receive commands and send positioning signals. A positioning antenna based on a single vertical plane symmetrical structure is set along the boundary line that prohibits the shopping cart from moving to receive the positioning signal sent by the shopping cart. The vertical plane of the positioning antenna corresponds to the boundary line that prohibits the shopping cart from moving to move. By comparing the RSSI values ​​of the positioning signals from the shopping cart received by the directional antennas on both sides of the vertical plane of the positioning antenna, it is determined which side of the boundary line prohibiting the shopping cart from moving to move is located. When the shopping cart is positioned outside the boundary line prohibiting the shopping cart from moving to move, or, based on the positioning results at different times, it is determined that the shopping cart has moved from the inside to the outside of the boundary line prohibiting the shopping cart from moving to move, a locking command is sent to the shopping cart. After receiving the locking command, the shopping cart activates the braking mechanism to lock the shopping cart.

15. The shopping cart control method based on single vertical plane comparison according to claim 14, characterized in that, The location signal sent by the shopping cart includes the status information of the shopping cart being locked or unlocked. When the shopping cart is inside the boundary that prevents the shopping cart from being pushed out and is in a locked state, an unlock command is sent to the shopping cart. After receiving the unlock command, the shopping cart activates the braking mechanism to unlock the shopping cart.

16. A shopping cart control system based on single vertical plane comparison, comprising a shopping cart as the object to be positioned, a base station for positioning and controlling the shopping cart, the shopping cart being equipped with a braking mechanism to limit the cart's movement, and a signal transceiver for sending positioning signals and receiving control commands. The base station includes positioning antennas for receiving positioning signals, signal processing modules equal in number to the directional antennas in the positioning antennas, and a controller for positioning determination and generating control commands. The positioning antenna is the aforementioned positioning antenna based on a single vertical plane symmetrical structure. The positioning antenna is set along the boundary line that prevents the shopping cart from being pushed out. The vertical plane of the positioning antenna corresponds to the boundary line that prevents the shopping cart from being pushed out. Each directional antenna in the positioning antenna is connected to a signal processing module. Each signal processing module calculates and outputs the RSSI value of the positioning signal received by the connected directional antenna. Each signal processing module is connected to a controller. The controller compares the RSSI values ​​of the positioning signals from the shopping cart received by the directional antennas on both sides of the vertical plane of the positioning antenna to determine which side of the boundary line prevents the shopping cart from being pushed out. When the shopping cart is positioned outside the boundary line, or, based on the positioning results at different times, it is determined that the shopping cart has moved from the inside to the outside of the boundary line, the base station sends a locking command to the shopping cart. The shopping cart receives and responds to the locking command, and activates the braking mechanism to lock the shopping cart.

17. The shopping cart control system based on single vertical plane comparison according to claim 16, characterized in that, The anti-theft base station also includes a transmitting antenna for sending control commands.

18. The shopping cart control system based on single vertical plane comparison according to claim 16, characterized in that, The positioning antenna consists of multiple antennas, all of which are connected to a controller to form a base station. The controller compares and judges the RSSI value of each positioning antenna. When the judgment result of any positioning antenna meets the control condition, a control command is issued, or when the judgment results of multiple positioning antennas meet the control condition simultaneously, a control command is issued.

19. The shopping cart control system based on single vertical plane comparison according to claim 16, characterized in that, The positioning antennas include multiple antennas. Each positioning antenna or several positioning antennas are connected to a controller to form a base station. The controller of each base station independently compares and judges the RSSI value of the positioning antenna connected to it, and issues control commands based on the judgment result.

20. The shopping cart control system based on single vertical plane comparison according to claim 16, characterized in that, The positioning antennas include multiple ones. Each positioning antenna or several positioning antennas are connected to a controller to form a base station. Each anti-theft base station outputs its judgment result to a central controller, which makes a control decision based on the judgment results of multiple anti-theft base stations.

21. The shopping cart control system based on single vertical plane comparison according to claim 20, characterized in that, One base station is selected as the main anti-theft base station, and the other base stations are designated as auxiliary base stations. The controller of the main base station is used as the overall controller, and all auxiliary base stations communicate with the main base station.

22. The shopping cart control system based on single vertical plane comparison according to claim 20, characterized in that, A separate central controller is set up independently of each base station, and each base station communicates with the central controller.

23. A positioning antenna based on a dual vertical plane symmetry structure, comprising multiple directional antennas arranged together, wherein there are at least four directional antennas, the multiple directional antennas forming a centrally symmetric structure with the intersection of two mutually perpendicular vertical planes as the central axis, any two directional antennas that form a symmetric relationship along the vertical planes are identical, at least one pair of directional antennas symmetric along a first vertical plane have partially overlapping horizontal plane effective coverage areas, and at least one pair of directional antennas symmetric along a second vertical plane have partially overlapping horizontal plane effective coverage areas.

24. The positioning antenna based on a dual vertical symmetrical structure according to claim 23, characterized in that, The multiple directional antennas are divided into four groups, which are located in four right-angled regions separated by two vertical planes. The first and second groups of directional antennas are symmetrical along the first vertical plane, the second and third groups are symmetrical along the second vertical plane, the third and fourth groups are symmetrical along the first vertical plane, and the fourth and first groups are symmetrical along the second vertical plane. In any two groups of directional antennas that form a symmetrical relationship along the vertical plane, at least one pair of directional antennas that are symmetrical along the vertical plane will have partially overlapping horizontal plane coverage areas.

25. The positioning antenna based on a dual vertical symmetric structure according to claim 24, characterized in that, The four sets of directional antennas are 90 degrees rotationally symmetrical about the intersection of the two vertical planes, and the four directional antennas that form a 90-degree rotational symmetry relationship are identical.

26. The positioning antenna based on a dual vertical symmetric structure according to claim 23, characterized in that, The plurality of directional antennas consists of four identical antennas, which are rotated 90 degrees symmetrically about the intersection of the two vertical planes. The effective horizontal coverage areas of any two directional antennas that form a symmetrical relationship along the vertical planes partially overlap.

27. The positioning antenna based on a dual vertical symmetric structure according to claim 23, characterized in that, The plurality of directional antennas includes one or more pairs of directional antennas disposed on a first vertical plane or a second vertical plane.

28. A positioning method based on dual vertical plane comparison is used to determine the relative position of a target object with respect to two mutually perpendicular target vertical planes. The method uses the target object as a signal transmitter and sets up multiple directional antennas in a centrally symmetrical structure with the intersection line of the two target vertical planes as the central axis. Two directional antennas forming a symmetrical relationship along any target vertical plane are identical. The included angle between two directional antennas symmetrical along the target vertical plane is set such that at least one pair of directional antennas symmetrical along the first target vertical plane partially overlaps in their horizontal effective coverage area, and at least one pair of directional antennas symmetrical along the second target vertical plane partially overlaps in their horizontal effective coverage area. By comparing the RSSI values ​​of the signals emitted by the target object received by the directional antennas on both sides of a target vertical plane, the method determines which side of the target vertical plane the target object is located on. Then, combining the two comparison results, the method further determines which of the four right-angled regions formed by the two target vertical planes the target object is located in.

29. A method for controlling the reverse movement of a shopping cart, used to control the shopping cart to move in reverse within an aisle, comprising a braking mechanism on the shopping cart to limit its movement, and functions for sending positioning signals and receiving and responding to commands; a positioning antenna based on a dual-vertical-plane symmetrical structure as described in claim 23 is respectively arranged on both sides of the aisle, the two positioning antennas being laterally aligned along a boundary line perpendicular to the length of the aisle to prevent the shopping cart from moving in reverse; the first vertical plane and the second vertical plane of the first positioning antenna being respectively arranged corresponding to the boundary line preventing the shopping cart from moving in reverse and the first side boundary of the aisle; the first vertical plane and the second vertical plane of the second positioning antenna being respectively arranged corresponding to the boundary line preventing the shopping cart from moving in reverse and the second side boundary of the aisle; comparing the RSSI values ​​of the directional antennas on both sides of the second vertical plane of the first positioning antenna to determine whether the shopping cart is located inside the first side boundary of the aisle. The RSSI values ​​of the directional antennas on both sides of the second vertical plane of the second positioning antenna are compared to determine whether the shopping cart is located inside the second side boundary of the passage. Combining the two comparison results, it is determined whether the shopping cart is located inside the passage. The RSSI values ​​of the directional antennas on both sides of the first vertical plane of the first positioning antenna or the second positioning antenna are compared to determine which side of the boundary line prohibiting the shopping cart from being pushed out in reverse. Alternatively, the RSSI values ​​of the directional antennas on both sides of the first vertical plane of the first positioning antenna and the second positioning antenna are compared respectively. Based on the same comparison result, it is determined which side of the boundary line prohibiting the shopping cart from being pushed out in reverse is located. The positioning results at different times are compared. When the shopping cart moves in reverse from the inside to the outside of the boundary line prohibiting the shopping cart from being pushed out in reverse, a locking command is sent to the shopping cart. The shopping cart receives and responds to the locking command and activates the braking mechanism to lock the shopping cart.

30. A positioning system based on dual vertical plane comparison for locating an object that has passed through a target boundary, comprising a positioning device and an object to be located, wherein the object to be located is equipped with a signal transmitter, the positioning device comprising two positioning antennas based on a dual vertical plane symmetrical structure as described in claim 23, a plurality of signal processing modules, and a controller for comparison and judgment, wherein each directional antenna of the two positioning antennas is connected to a signal processing module, each signal processing module calculates and outputs the RSSI value of the signal received by the connected directional antenna, wherein the first vertical plane of the first positioning antenna is set to correspond to the target boundary, the first vertical plane of the second positioning antenna is set to correspond to the target boundary, and the controller compares the first vertical plane of the first positioning antenna with the target boundary. The controller compares the RSSI values ​​of the directional antennas on both sides of the second vertical plane of the first positioning antenna to determine whether the object being located is inside the first end of the target boundary. It then compares the RSSI values ​​of the directional antennas on both sides of the second vertical plane of the second positioning antenna to determine whether the object being located is inside the second end of the target boundary. Combining the two comparison results, the controller determines whether the object being located is within the width range of the target boundary. Alternatively, the controller compares the RSSI values ​​of the directional antennas on both sides of the first vertical plane of the first or second positioning antenna to determine which side of the target boundary the object is located on.

31. The positioning system based on dual vertical plane comparison according to claim 30, characterized in that, The positioning device is equipped with only one controller, and the first positioning antenna and the second positioning antenna are respectively connected to this controller through a signal processing module.

32. The positioning system based on dual vertical plane comparison according to claim 30, characterized in that, The first positioning antenna serves as the main positioning antenna and is configured with a main controller. The signal processing modules connected to each directional antenna in the first positioning antenna are respectively connected to the main controller. The second positioning antenna serves as the auxiliary positioning antenna and is configured with an auxiliary controller. The signal processing modules connected to each directional antenna in the second positioning antenna are respectively connected to the auxiliary controller.

33. The positioning system based on dual vertical plane comparison according to claim 32, characterized in that, The main controller compares the RSSI values ​​of the directional antennas on both sides of the second vertical plane of the first positioning antenna, and the auxiliary controller compares the RSSI values ​​of the directional antennas on both sides of the second vertical plane of the second positioning antenna. The comparison results are sent to the main controller. The main controller determines whether the object being positioned is located within the width range of the target boundary based on the combination of the two comparison results. The main controller compares the RSSI values ​​of the directional antennas on both sides of the first vertical plane of the first positioning antenna to determine which side of the target boundary the object being positioned is located on.

34. The positioning system based on dual vertical plane comparison according to claim 32, characterized in that, The main controller compares the RSSI values ​​of the directional antennas on both sides of the second vertical plane of the first positioning antenna with the RSSI values ​​of the directional antennas on both sides of the first vertical plane. The auxiliary controller compares the RSSI values ​​of the directional antennas on both sides of the second vertical plane of the second positioning antenna with the RSSI values ​​of the directional antennas on both sides of the first vertical plane. If the comparison results of the RSSI values ​​of the directional antennas on both sides of the first vertical plane of the two positioning antennas are different, the positioning is considered to have failed. If the results are the same, the main controller determines which side of the target boundary the object to be positioned is located on based on the same comparison result.

35. A shopping cart control method based on dual vertical plane comparison, wherein the shopping cart is the object to be positioned, a braking mechanism is configured on the shopping cart to restrict its movement, and the shopping cart is also equipped with the functions of receiving instructions and sending positioning signals. A positioning antenna based on a dual vertical plane symmetrical structure is set at each end of a boundary line that prohibits the shopping cart from moving to receive the positioning signals emitted by the shopping cart. The first vertical plane of the two positioning antennas corresponds to the boundary line prohibiting the shopping cart from moving. By comparing the RSSI values ​​of the directional antennas on both sides of the second vertical plane of the two positioning antennas, it is determined whether the shopping cart is within the width range of this boundary line prohibiting the shopping cart from moving. The first positioning antenna or the second positioning antenna is then compared. The RSSI values ​​of the two directional antennas on the first vertical plane are used to determine which side of a boundary line prohibiting the cart from being pushed out is the shopping cart. Alternatively, the RSSI values ​​of the two directional antennas on the first vertical plane of the first and second positioning antennas are compared respectively, and the shopping cart is determined to be on which side of a boundary line prohibiting the cart from being pushed out is the shopping cart based on the same comparison result. When the shopping cart is positioned outside the width of a boundary line prohibiting the cart from being pushed out, or based on the positioning results at different times, it is determined that the shopping cart has moved from the inside to the outside of the width of a boundary line prohibiting the cart from being pushed out, and a locking command is sent to the shopping cart. After receiving the locking command, the shopping cart activates the braking mechanism to lock the shopping cart.

36. The shopping cart control method based on dual vertical plane comparison according to claim 35, characterized in that, The location signal sent by the shopping cart includes the status information of the shopping cart being locked or unlocked. When the shopping cart is located inside a boundary line that prevents the shopping cart from being pushed out, and is in a locked state, an unlock command is sent to the shopping cart. After receiving the unlock command, the shopping cart activates the braking mechanism to unlock the shopping cart.

37. A shopping cart control system based on dual vertical plane comparison, comprising a shopping cart as the object to be positioned, a base station for positioning and controlling the shopping cart, the shopping cart being equipped with a braking mechanism to restrict the cart's movement, and a transceiver for sending positioning signals and receiving control commands. The base station is equipped with positioning antennas for receiving positioning signals, signal processing modules of the same number as the directional antennas in the positioning antennas, and a controller for positioning judgment and generating control commands. The positioning antennas are the positioning antennas based on a dual vertical plane symmetry structure as described in claim 23. The positioning antennas include a first positioning antenna and a second positioning antenna respectively disposed at both ends of a boundary line preventing the shopping cart from being pushed out. The first vertical planes of the first and second positioning antennas overlap and correspond to the boundary line preventing the shopping cart from being pushed out. Each directional antenna in the positioning antennas is connected to a signal processing module, and each signal processing module calculates and outputs the RSSI value of the positioning signal received by the connected directional antenna. Each signal processing module is connected to the controller. The controller compares the RSSI values ​​of the directional antennas on both sides of the second vertical plane of the two positioning antennas to determine whether the shopping cart is within the width range of the boundary line that prohibits the shopping cart from being pushed out. The controller compares the RSSI values ​​of the directional antennas on both sides of the first vertical plane of the first positioning antenna or the second positioning antenna to determine which side of the boundary line the shopping cart is located on. Alternatively, the controller compares the RSSI values ​​of the directional antennas on both sides of the first vertical plane of the first positioning antenna and the second positioning antenna respectively, and determines which side of the boundary line the shopping cart is located on based on the same comparison result. When the shopping cart is located outside the width range of the boundary line that prohibits the shopping cart from being pushed out, or based on the positioning results at different times, it is determined that the shopping cart has moved from the inside to the outside of the width range of the boundary line that prohibits the shopping cart from being pushed out, and a locking command is sent to the shopping cart. After receiving the locking command, the shopping cart activates the braking mechanism to lock the shopping cart.

38. The shopping cart control system based on dual vertical plane comparison according to claim 37, characterized in that, The base station is also equipped with a transmitting antenna for sending control commands.

39. The shopping cart control system based on dual vertical plane comparison according to claim 37, characterized in that, The base station is configured with only one controller, and all signal processing modules are connected to this one controller.

40. The shopping cart control system based on dual vertical plane comparison according to claim 37, characterized in that, The base station includes a main base station and an auxiliary base station. The main base station includes a first positioning antenna, a signal processing module with the same number of directional antennas as the first positioning antenna, and a first controller. The auxiliary base station includes a second positioning antenna, a signal processing module with the same number of directional antennas as the second positioning antenna, and a second controller. The auxiliary base station communicates with the main base station (through a wired or additionally configured communication module and antenna). The second controller compares the RSSI values ​​of the directional antennas on both sides of the second vertical plane of the second positioning antenna and sends the comparison result to the first controller. Optionally, the second controller also compares the RSSI values ​​of the directional antennas on both sides of the first vertical plane of the second positioning antenna and sends the comparison result to the first controller. The first controller compares the RSSI values ​​of the directional antennas on both sides of the second vertical plane of the first positioning antenna and, in conjunction with the comparison result of the second controller for the second vertical plane, determines whether the shopping cart is located within the width range of the boundary line that prohibits the shopping cart from being pushed out. The first controller compares the RSSI values ​​of the directional antennas on both sides of the first vertical plane of the first positioning antenna and, based on the comparison result, determines which side of the boundary line prohibiting the shopping cart from being pushed out, or, optionally, determines which side of the boundary line prohibiting the shopping cart from being pushed out, based on the same comparison result as the second controller for the first vertical plane. When the shopping cart is located outside the width range of the boundary line prohibiting the shopping cart from being pushed out, or, based on the positioning results at different times, determines that the shopping cart has moved from the inside to the outside of the width range of the boundary line prohibiting the shopping cart from being pushed out, the first controller generates a locking command and sends it to the shopping cart through the transmitting antenna or one of the directional antennas of the first positioning antenna.

41. A positioning antenna based on a four-quadrant distribution structure, comprising multiple identical directional antennas, wherein the directional antennas are circumferentially distributed at the same horizontal height with the intersection of two mutually perpendicular vertical planes as the central axis, and the radiation direction of each directional antenna is radially outward with the central axis as the center. The vertical projection of the two vertical planes divides the horizontal plane into four quadrants, and each quadrant has at least one directional antenna.

42. The positioning antenna based on a four-quadrant distribution structure according to claim 41, characterized in that, The directional antenna comprises four groups, each located in one of the four quadrants. The four groups of antennas form a 90-degree rotationally symmetrical structure with the intersection of two vertical planes as the central axis.

43. The four-quadrant distribution structure based positioning antenna according to claim 42, characterized in that, The four antennas form a centrally symmetrical structure with the intersection of the two vertical planes as the central axis.

44. The four-quadrant distribution structure based positioning antenna according to claim 43, characterized in that, The four antennas form a ring array structure with the intersection of the two vertical planes as the central axis.

45. A positioning method based on vector operations for determining the relative position of a target object with respect to two mutually perpendicular target vertical planes. The method uses the target object as a signal transmitter, with the intersection of the two target vertical planes as the central axis, and multiple directional antennas distributed circumferentially. In the four right-angled regions formed by the two target vertical planes, at least one directional antenna is distributed in each right-angled region. The RSSI value of the same signal received from the target object by each directional antenna is used as the magnitude of the vector, and the angle of the directional antenna is used as the direction of the vector to obtain the detection vector of that directional antenna. The detection vectors of each directional antenna are added together to obtain a positioning vector. The quadrant in which the direction of this positioning vector is located is used to determine which right-angled region the target object is located in.

46. ​​A positioning system based on vector operations for locating an object that has passed through a target boundary, comprising a positioning device and an object to be located, wherein the object to be located is equipped with a signal transmitter, the positioning device comprising two positioning antennas based on a four-quadrant distribution structure as described in claim 41, a plurality of signal processing modules, and a controller for vector operation judgment, wherein each directional antenna of the two positioning antennas is connected to a signal processing module, each signal processing module calculates and outputs the RSSI value of the signal received by the connected directional antenna, wherein the first vertical plane of the first positioning antenna and the first vertical plane of the second positioning antenna are respectively set to correspond to the target boundary, the controller uses the RSSI value of the directional antenna as the magnitude of the vector and the angle of the directional antenna as the direction of the vector to generate a detection vector of the directional antenna, the controller adds the detection vectors of all the directional antennas of the positioning antenna to obtain the positioning vector of the positioning antenna, and the controller combines the directions of the positioning vectors of the two positioning antennas to determine whether the object to be located is within the width of the target boundary and on which side of the target boundary it is located.

47. A shopping cart control method based on vector operations, wherein the shopping cart is the object to be positioned, a braking mechanism is configured on the shopping cart to restrict its movement, and the shopping cart is also equipped with the functions of receiving instructions and sending positioning signals. A positioning antenna with a four-quadrant distribution structure as described in claim 41 is respectively set at both ends of a boundary line that prevents the shopping cart from being pushed out, to receive the positioning signals emitted by the shopping cart. The first vertical plane of the two positioning antennas corresponds to the boundary line that prevents the shopping cart from being pushed out. The RSSI value of the directional antenna is used as the magnitude of the vector, and the angle of the directional antenna is used as the direction of the vector to obtain a detection vector for the directional antenna. This vector is then used to... The detection vectors of all directional antennas of a positioning antenna are added together to obtain the positioning vector of that positioning antenna. The directions of the positioning vectors of the two positioning antennas are combined to determine whether the shopping cart is located within the width of a boundary line that prohibits shopping carts from being pushed out, and on which side of the boundary line it is located. If the shopping cart is located outside the boundary line, or, based on the positioning results at different times, it is determined that the shopping cart has moved from the inside to the outside of the boundary line, a locking command is sent to the shopping cart. After receiving the locking command, the shopping cart activates the braking mechanism to lock the shopping cart.

48. The vector operation based shopping cart control method of claim 47, wherein, The location signal sent by the shopping cart includes the status information of the shopping cart being locked or unlocked. When the shopping cart is located inside a boundary line that prevents the shopping cart from being pushed out, and is in a locked state, an unlock command is sent to the shopping cart. After receiving the unlock command, the shopping cart activates the braking mechanism to unlock the shopping cart.

49. A shopping cart control system based on vector operations, comprising a shopping cart as the object to be located, a base station for locating and controlling the shopping cart, the shopping cart being equipped with a braking mechanism to limit the cart's movement, and a signal transceiver for sending positioning signals and receiving control commands. The base station is equipped with positioning antennas for receiving positioning signals, signal processing modules having the same number as the directional antennas in the positioning antennas, and a controller for determining positioning and generating control commands. The positioning antenna is the positioning antenna based on a four-quadrant distribution structure as described in claim 41. The positioning antenna includes a first positioning antenna and a second positioning antenna respectively disposed at both ends of a boundary line that prohibits the shopping cart from being pushed out. The first vertical planes of the first positioning antenna and the second positioning antenna overlap and correspond to the boundary line that prohibits the shopping cart from being pushed out. Each directional antenna in the positioning antenna is connected to a signal processing module. Each signal processing module calculates and outputs the RSSI value of the positioning signal received by the connected directional antenna. Each signal processing module is connected to the controller. The controller uses the RSSI value of the directional antenna as the magnitude of the vector and the angle of the directional antenna as the direction of the vector to generate a detection vector for the directional antenna. The controller adds the detection vectors of all directional antennas of a positioning antenna to obtain the positioning vector of that positioning antenna. The controller combines the directions of the positioning vectors of the two positioning antennas to determine whether the shopping cart is located within the width of a boundary line that prohibits shopping carts from being pushed out, and on which side of the boundary line it is located. When the shopping cart is located outside the boundary line that prohibits shopping carts from being pushed out, or, based on the positioning results at different times, it is determined that the shopping cart has moved from the inside to the outside of the boundary line that prohibits shopping carts from being pushed out, the base station sends a locking command to the shopping cart. After receiving the locking command, the shopping cart activates the braking mechanism to lock the shopping cart.

50. The vector operations based shopping cart control system of claim 49, wherein, The base station is also equipped with a transmitting antenna for sending control commands.

51. The vector operations based shopping cart control system of claim 49, wherein, The base station is configured with only one controller, and all signal processing modules are connected to this one controller.

52. The shopping cart control system based on vector operations according to claim 49, characterized in that, The base station includes a main base station and a secondary base station. The main base station includes a first positioning antenna, a signal processing module with the same number of directional antennas as the first positioning antenna, and a first controller; optionally, it also includes a transmitting antenna. The secondary base station includes a second positioning antenna, a signal processing module with the same number of directional antennas as the second positioning antenna, and a second controller. The secondary base station communicates with the main base station. The second controller adds the detection vectors of all the directional antennas of the second positioning antenna to obtain the positioning vector of the second positioning antenna, and sends the direction of the positioning vector of the second positioning antenna to the first controller. The first controller adds the detection vectors of all the directional antennas of the first positioning antenna. The first controller calculates the positioning vector of the first positioning antenna and combines the directions of the positioning vectors of the first and second positioning antennas to determine whether the shopping cart is located within the width range of the no-pull-out boundary and on which side of the no-pull-out boundary it is located on. When the shopping cart is located outside the no-pull-out boundary, or, based on the positioning results at different times, it is determined that the shopping cart has moved from the inside to the outside of the no-pull-out boundary, the first controller generates a locking command and sends it to the shopping cart through the transmitting antenna or one of the directional antennas of the first positioning antenna.

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