Ultra-wideband assisted precise positioning method

An ultra-wideband assisted precise positioning method includes: arranging a plurality of base stations in a target area; configuring a mobile base station to move to a plurality of predetermined positions; configuring a GPS module to obtain GPS position information and GPS altitude information; configuring first ultra-wideband communication modules and a second ultra-wideband communication module to measure distance information; configuring a computing module to execute a first positioning algorithm to calculate a plurality of base station coordinates; arranging a third ultra-wideband communication module on an object to be measured; configuring the first ultra-wideband communication modules and the third ultra-wideband communication module to obtain detection distances; and configuring the computing module to execute a second positioning algorithm to calculate a positioning position of the object to be measured based on the detection distances and the plurality of base station coordinates.

CROSS-REFERENCE TO RELATED PATENT APPLICATION

This application claims the benefit of priority to Taiwan Patent Application No. 109110445, filed on Mar. 27, 2020. The entire content of the above identified application is incorporated herein by reference.

FIELD OF THE DISCLOSURE

The present disclosure relates to a positioning method, and more particularly to an ultra-wideband assisted precise positioning method.

BACKGROUND OF THE DISCLOSURE

In existing positioning technology, GPS signals are mostly used as a medium to obtain position information.

When performing positioning in indoor spaces, due to limited GPS signals, WI-FI®, BLUETOOTH®, and 4G base stations are currently used to assist indoor GPS positioning; however, centimeter-level positioning cannot be achieved.

In addition, in some positioning systems, ultra-wideband signals are used to achieve centimeter-level positioning, by first obtaining a time difference between a base station and an object to be measured, and then obtains a position of the object to be measured through triangulation.

However, the positioning in this way requires manual measurement to obtain the coordinates of the base stations, which incurs a large amount of engineering cost and fails to meet mobility requirements, and it is also difficult to measure the coordinates of multiple base stations manually in a large indoor space.

Therefore, there is an urgent need for a positioning system that is fast and simple, and that can meet the needs of mobility and achieve precise positioning.

SUMMARY OF THE DISCLOSURE

In response to the above-referenced technical inadequacies, the present disclosure provides an ultra-wideband assisted precise positioning method.

In one aspect, the present disclosure provides an ultra-wideband assisted precise positioning method including: arranging a plurality of base stations in a target area, in which each of the plurality of base stations includes a first processing circuit, a first ultra-wideband communication module and a first wide area network communication module. The first ultra-wideband communication module is configured to receive and transmit ultra-wideband signals, and the first wide area network communication module is configured to connect to a wide area network. The method further includes providing a mobile base station, which includes a moving module, a second wide area network communication module, a second ultra-wideband communication module, a second processing circuit, and a global positioning system (GPS) module. The moving module is configured to provide mobile power output, and the second wide area network communication module is configured to communicate with the plurality of base stations through the wide area network. The second ultra-wideband communication module is configured to receive and transmit ultra-wideband signals. The second processing circuit is configured to control the moving module, and the GPS module is configured to obtain GPS position information and GPS altitude information of the mobile base station. The method further includes: configuring the second processing circuit to move the mobile base station to a plurality of predetermined positions in the target area, and performing the following steps in response to the mobile base station being located at each of the plurality of predetermined positions: configuring the GPS module to obtain the GPS position information and the GPS altitude information; configuring each of the plurality of first ultra-wideband communication modules and the second ultra-wideband communication module to measure distance information between each of the base stations and the mobile base station; configuring a server to obtain, through the wide area network, the distance information, the GPS position information, and the GPS altitude information obtained at the predetermined positions; configuring a computing module of the server to execute a first positioning algorithm to calculate a plurality of base station coordinates of the plurality of base stations; arranging a third ultra-wideband communication module on an object to be measured in the target area; configuring the plurality of first ultra-wideband communication modules to communicate with the third ultra-wideband communication module to obtain a plurality of detection distances between the object to be measured and the plurality of base stations, respectively; configuring the server to obtain the plurality of detection distances and the plurality of base station coordinates through the wide area network; and configuring the computing module to execute a second positioning algorithm to calculate a positioning position of the object to be measured based on the plurality of detection distances and the plurality of base station coordinates.

Therefore, the ultra-wideband assisted precise positioning method provided by the present disclosure can quickly obtain coordinates of the base stations by utilizing the mobility of the mobile base station, and can precisely obtain absolute coordinates of fixed ultra-wideband (UWB) base stations according to a flight path of dynamic unmanned aerial vehicle (UAV) and UWB distances. After the coordinates of the UWB base stations are obtained through the method, centimeter-level indoor positioning can be achieved, which is suitable for precise indoor positioning in a large indoor space.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

Reference is made toFIGS. 1 to 3,FIG. 1is a block diagram of an ultra-wideband assisted precise positioning system according to one embodiment of the present disclosure,FIG. 2is a block diagram of base stations and a mobile base station according to one embodiment of the present disclosure, andFIG. 3is a flowchart of an ultra-wideband assisted precise positioning method according to one embodiment of the present disclosure. As shown inFIGS. 1 to 3, before the ultra-wideband assisted precise positioning method of the present disclosure is explained, an ultra-wideband assisted precise positioning system1utilized by the present disclosure is first introduced. As shown inFIG. 1, the ultra-wideband assisted precise positioning system1includes a plurality of base stations10,11,12and13, a mobile base station14and a server15.

Each of the plurality of base stations10,11,12,13, for example, the base station10, includes a first processing circuit100, a first ultra-wideband communication module102, and a first wide area network (WAN) communication module104, and the base stations11,12,13and the base station10have the same configurations. In the present embodiment, the quantity of base stations10,11,12,13is at least four.

The mobile base station14can include a moving module140, a second wide area network (WAN) communication module142, a second ultra-wideband communication module144, a global positioning system (GPS) module146, and a second processing circuit148.

The second WAN communication module142is configured to communicate with the base stations through the wide area network (WAN)16. The second processing circuit148is configured to control the moving module140.

The mobile base station14can be installed on an unmanned aerial vehicle (UAV), which generally can be a variety of radio controlled aircrafts that do not require a human pilot. The mobile base station14has a moving module140, such as a propeller controller, for providing mobile power output, and receiving external control signals to control the mobile base station14to move. In addition, the UAV can be combined with remotely controlled machine communication (MTC) components such as multi-axis gyroscopes, barometers/infrared ranging components, ultrasonic ranging components, cameras, and the like. In this embodiment, the moving module140is a flight power module configured to provide flight power output.

The first ultra-wideband communication module102and the second ultra-wideband communication module144are configured to send and receive ultra-wideband signals. In detail, ultra-wideband (UWB) is a wireless personal area network communication technology with low power consumption and high-speed transmission, and suitable for wireless communication applications requiring high-quality services. UWB can be used in fields such as wireless personal area networks (WPAN), home network connection and short-range radar, and UWB uses pulse signals to receive and transmit ultra-wideband signals.

The first processing circuit100and the second processing circuit148can include a microcontroller and a microprocessor. The first processing circuit100can be used to control the first WAN communication module104to connect to the WAN16and control the first ultra-wideband communication module102to transmit and receive ultra-wideband signals. The second processing circuit148can be used to control the moving module140, the second WAN communication module142, the second ultra-wideband communication module144, and the GPS module146.

The GPS module146is configured to obtain GPS position information and GPS altitude information of the mobile base station14. It should be noted that the plurality of base stations of the present disclosure, for example, the base stations10,11,12,13do not substantially need to be provided with GPS modules, but the present disclosure is not limited thereto.

The first WAN communication module104and the second WAN communication module142can be, for example, long range (LoRa) wide area network communication modules configured to connect to the WAN16. In the present disclosure, long-distance transmission advantages of LoRa can be utilized to greatly expand the coverage distance and operating performance of the ultra-wideband assisted precise positioning system1. In addition, the base stations10,11,12,13and the mobile base station14can also communicate with one another through the WAN16.

In addition, the server15may include a computing module150, a memory unit152, and a communication module154. The communication module154is configured to connect to the WAN16, the memory unit152stores a first positioning algorithm ALG1and a second positioning algorithm ALG2, and the memory unit152can be, for example, a volatile memory or a non-volatile memory, and the computing module150can include a central processing unit for executing the first positioning algorithm ALG1and the second positioning algorithm ALG2.

Reference is made toFIGS. 3 and 4,FIG. 3is a flowchart of the ultra-wideband assisted precise positioning method according to one embodiment of the present disclosure, andFIG. 4is a schematic diagram showing construction of the ultra-wideband assisted precise positioning system according to one embodiment of the present disclosure.

As shownFIGS. 3 and 4, the ultra-wideband assisted precise positioning method according to one embodiment of the present disclosure includes the following steps:

Step S100: arranging a plurality of base stations10,11,12and13in a target area Area. For example, four or more base stations can be placed indoors or outdoors.

Step S101: configuring the mobile base station14to move to a plurality of predetermined positions in the target area Area, respectively. For example, the mobile base station14can be installed on an unmanned aerial vehicle UAV, the server15can be configured to communicate with the mobile base station14, and the server15can transmit a moving command signal to the mobile base station14according to a predetermined route stored in the memory unit152.

In response to the mobile base station14receiving the moving command signal through the second WAN communication module142, the second processing circuit148processes the moving command signal, and further controls the moving module140to output power so that the mobile base station14can move to the predetermined positions in the target area according to the predetermined route, such as predetermined positions A0, A1, A2, and A3shown inFIG. 4, and stay for a predetermined time when arriving the predetermined positions.

In response to the mobile base station14staying at these predetermined positions, the following steps can be further performed:

Step S102: configuring the GPS module to obtain GPS position information and GPS altitude information.

Step S103: configuring the first ultra-wideband communication modules102and the second ultra-wideband communication modules144of the base stations10,11,12, and13to measure the distance information between the base stations10,11,12, and13and the mobile base station14. For example, the unmanned aerial vehicle UAV can be controlled to fly outside the base stations10,11,12,13and hover after flying for a certain period of time along a certain path. At the same time, the second ultra-wideband communication module144is configured to transmit UWB signals to the base stations10,11,12,13. GPS coordinates of the four positions and the corresponding multiple distances between the base stations10,11,12, and13can be obtained after the UAV hovers for four times or more.

After the mobile base station14obtains the data at the predetermined positions A0, A1, A2, and A3, the method proceeds to step S104: configuring the server15to obtain, through the WAN16, the distance information, for example, distance information r0, r1, r2and r3, the GPS position information such as the coordinates of the predetermined positions A0, A1, A2, A3, and the GPS altitude information obtained at the predetermined positions A0, A1, A2, and A3. This step is used to collect the data acquired by the mobile base station14and prepare for calculation by the server15. In some embodiments, the base stations10,11,12, and13are located in an indoor space, and the predetermined positions A0, A1, A2, and A3can be located in an outdoor space with respect to the indoor space. However, it should be noted that the predetermined positions A0, A1, A2, and A3must be within the ranges that can respectively communicate with the base stations10,11,12, and13to ensure that the distance information can be measured correctly.

Optionally, when the second processing circuit148of the mobile base station14or the first processing circuits100of the base stations10,11,12, and13have sufficient computing power, the distance information, data collection and calculation for the GPS position information and the GPS altitude information can also be performed by the base station14and one of the base stations10,11,12, and13, and are not limited to be performed by the server15.

Step S105: configuring the computing module150of the server15to execute the first positioning algorithm ALG1to calculate a plurality of base station coordinates BS0, BS1, BS2and BS3of the base stations10,11,12, and13. In detail, when the mobile base station14stays at these predetermined positions, the GPS coordinates of the four positions and the distances corresponding to the base stations10,11,12, and13are obtained, and a least squares technique (four-sided positioning) can be further used to obtain absolute position coordinates of each of the base stations10,11,12, and13.

For example, the first positioning algorithm ALG1can include the least squares technique, which can be calculated by the following equation (1):

which mainly uses the predetermined position A0as an original point, and calculates relative coordinates of the predetermined positions A1, A2, and A3based on the obtained GPS position information and the obtained GPS altitude information.

and distances and relative coordinates of the base station14and the base station10obtained at the four predetermined positions A0, A1, A2, A3are substituted in the above equation.andare substituted into the equation (1), and then the base station coordinates BS0, BS1, BS2and BS3can be obtained.

In this way, the positioning system is established.

Step S106: arranging the third ultra-wideband communication module17on an object to be measured TAR in the target area.

Step S107: configuring the first ultra-wideband communication modules of the base stations10,11,12, and13to communicate with the third ultra-wideband communication module17to obtain detection distances respectively between the object to be measured TAR and the plurality of base stations10,11,12, and13.

Step S108: configuring the server15to obtain the detection distances through the WAN16.

Step S109: configuring the computing module150to execute the second positioning algorithm ALG2to calculate the positioning position of the object to be measured TAR according to the detection distances and the coordinates of the base stations10,11,12, and13.

In detail, after the coordinates of four (or more) base stations10,11,12, and13are arranged arbitrarily indoor/outdoor, the first ultra-wideband communication modules102of the base stations10,11,12, and13transmit UWB signal to the third ultra-wideband communication module17, the distances are then measured to obtain the distances to the object to be measured TAR, and the second positioning algorithm ALG2is utilized, for example, the least squares technique, to obtain the position of the object to be measured TAR.

Reference is made toFIGS. 5A and 5B,FIG. 5Ais a position distribution diagram of positioning an object to be measured by the ultra-wideband assisted precise positioning method and the existing GPS positioning system according to one embodiment of the present disclosure, andFIG. 5Bis a partially enlarged view ofFIG. 5A.

As shown inFIGS. 5A and 5B, objects BS0, BS1, BS2, and BS3represent the coordinates of the base stations10,11,12, and13, respectively, which are obtained by substituting the GPS position information obtained by the mobile base station14at four predetermined positions and the relative distances between the mobile base station14and each of the base stations10,11,12, and13into the least squares technique. Three objects to be measured are respectively arranged within and outside an area formed by the base stations10,11,12, and13, and positioning results Pos1(UWB), Pos2(UWB), Pos3(UWB) generated by the ultra-wideband assisted precise positioning method of the present disclosure and positioning results Pos1(GPS), Pos2(GPS), Pos3(GPS) generated by the existing GPS positioning are shown inFIGS. 5A and 5B.

Reference is further made to Table 1 below, which is a comparison of GPS and UWB relative position errors. It can be clearly seen fromFIG. 5Bthat the positioning results generated by the existing GPS positioning can no longer accurately identify the relative positions of the base stations, while the ultra-wideband assisted precise positioning method of the present disclosure can still accurately identify the relative positional relationship of the three objects to be measured, and the positioning accuracy is about 0.10 m. The positioning accuracy is higher inside the area formed by the base stations10,11,12, and13, and slightly lower outside the area. The positioning accuracy of the positioning results generated by the existing GPS positioning is about 1 to 2 m, so that it can be known that the ultra-wideband assisted precise positioning method of the present disclosure can improve the accuracy by an order of magnitude. In other words, in addition to verifying the feasibility of the ultra-wideband assisted precise positioning method provided by the present disclosure, the above results also show that the positioning system established by the mobile base station14quickly acquiring the coordinates of the base stations10,11,12,13can have a positioning result achieving a 10 cm-level positioning accuracy.

Therefore, the present disclosure can quickly obtain coordinates of the base stations by utilizing the mobility of the mobile base station, and can precisely obtain absolute coordinates of fixed UWB base stations according to a flight path of dynamic UAV and UWB distances. After the coordinates of the UWB base stations are obtained through the method, centimeter-level indoor positioning can be achieved, which is suitable for precise indoor positioning in large indoor spaces.

In another embodiment, when the server15transmits the moving command signal to the mobile base station14according to the predetermined route, the plurality of predetermined positions in the predetermined route can be set to have predetermined distances from one another, and the predetermined positions form a predetermined pattern.

After the mobile base station14stays at four predetermined positions and obtains the GPS position information and the GPS altitude information, the server15obtains the data and executes a pattern search algorithm to correct the GPS position information and the GPS altitude information to generate a plurality of corrected position information and a plurality of corrected altitude information.

Next, a total error is calculated using the cost function, which includes the distance error and the position error, which is expressed by the following equation (2):

where α is an empirical weight value,includes the corrected position information and the corrected altitude information, Dij2is a predetermined distance, {tilde over (x)}1is an initial position and initial altitude generated by the global satellite positioning module146, andis a predicted position and a predicted altitude. Therefore, the distance errors are errors between a plurality of relative distances and the predetermined distances, in which the relative distances are distances between the predicted positions and the corrected positions, and the position errors are errors between the predicted positions and the corrected positions. The empirical weight value a is adjusted and compared with a real position on the ground, such that the empirical weight value a with the smallest error can be found.

In conclusion, the ultra-wideband assisted precise positioning method provided by the present disclosure can quickly obtain coordinates of the base stations by utilizing the mobility of the mobile base station, and can precisely obtain an absolute coordinates of fixed UWB base stations according to a flight path of dynamic UAV and UWB distances. After the coordinates of the UWB base stations are obtained through the method, centimeter-level indoor positioning can be achieved, which is suitable for precise indoor positioning in large indoor spaces.