CN105203996A - Mobile device and indoor positioning method, system and device as well as anchor nodes thereof - Google Patents

Abstract

The invention discloses a mobile device and an indoor positioning method, system and device as well as anchor nodes thereof. According to the method, radio-frequency signals are sent to at least three anchor nodes through the mobile device, the mobile device receives ultrasonic waves sent by the three anchor nodes, the ultrasonic waves are sent by the corresponding anchor nodes under the trigger of the radio-frequency signals, transmission time for the ultrasonic wave sent by each anchor node to the mobile device is acquired, the distance between each anchor node and the mobile device is calculated according to the transmission time corresponding to each ultrasonic wave and the transmission speed of each ultrasonic wave, and then position coordinates of the mobile device are determined according to position coordinates of each anchor node and the distance between each anchor node and the mobile device. By the adoption of the mobile device, the indoor positioning method, system and device as well as the anchor nodes thereof, indoor positioning of the mobile device based on the ultrasonic technology is achieved, and the accuracy of indoor positioning of the mobile device is improved.

Description

Mobile equipment, indoor positioning method, system and device thereof, and anchor node

Technical Field

The present invention relates to positioning solutions, and in particular, to a mobile device, an indoor positioning method, a system, an apparatus, and an anchor node thereof.

Background

The positioning technology is widely applied to navigation, speed measurement, time measurement and the like, and when an object to be positioned is located in a building, such as an office building and a warehouse, the positioning accuracy of the traditional GPS positioning technology is obviously reduced, even the traditional GPS positioning technology cannot work, and the defects of the GPS positioning technology are required to be made up by an indoor positioning technology.

Currently, the solutions for indoor positioning of mobile devices include bluetooth technology, infrared technology, ultra-wideband technology, and wireless network technology. However, the above positioning solution has a problem of inaccurate positioning.

Disclosure of Invention

The technical problem solved by the embodiment of the invention is how to improve the accuracy of indoor positioning of the mobile equipment.

To solve the above problem, an embodiment of the present invention provides an indoor positioning method for a mobile device, where the method includes:

the mobile equipment sends radio frequency signals to at least 3 anchor nodes;

the mobile equipment receives ultrasonic waves sent by each anchor node respectively, and the ultrasonic waves are sent by the corresponding anchor nodes under the triggering of the radio frequency signals;

acquiring transmission time of ultrasonic waves transmitted by each anchor node to the mobile equipment;

calculating the distance between each anchor node and the mobile equipment according to the transmission time corresponding to each ultrasonic wave and the transmission speed of the ultrasonic wave;

and determining the position coordinate of the mobile equipment according to the position coordinate of each anchor node and the distance between each anchor node and the mobile equipment.

Optionally, the sending, by the mobile device, a radio frequency signal to at least 3 anchor nodes, receiving, by the mobile device, an ultrasonic wave sent by each anchor node, where the ultrasonic wave is sent by a corresponding anchor node under the trigger of the radio frequency signal includes:

the mobile equipment simultaneously sends the same radio frequency signal to all anchor nodes and receives different ultrasonic signals sent by each anchor node.

Optionally, the receiving, by the mobile device, the ultrasonic wave sent by each anchor node, where the ultrasonic wave is sent by the corresponding anchor node under the trigger of the radio frequency signal includes:

the mobile equipment sends different radio frequency signals to all anchor nodes in sequence, the ultrasonic signals sent by different anchor nodes are the same, and the interval time between two adjacent radio frequency signals sent by the mobile equipment is long enough to enable the mobile equipment to receive the ultrasonic signals sent by each anchor node in the same sequence.

Optionally, the interval time is greater than or equal to a quotient obtained by dividing the longest distance between two points in the indoor space where the mobile device is located by the transmission speed of the ultrasonic wave.

Optionally, the acquiring a transmission time of the ultrasonic wave transmitted by each anchor node to the mobile device includes: and taking the time difference between the time when the mobile device sends the radio frequency signal to the anchor node and the time when the mobile device receives the ultrasonic wave sent by the anchor node as the transmission time when the ultrasonic wave sent by the anchor node is transmitted to the mobile device.

Optionally, the radio frequency signal comprises: infrared, bluetooth, or wifi.

Optionally, the mobile device is an intelligent robot, the position coordinate is a two-dimensional coordinate composed of length and width, the heights of different anchor nodes are the same, and all the anchor nodes are located on at least two straight lines.

An embodiment of the present invention further provides an indoor positioning device for a mobile device, where the indoor positioning device for the mobile device includes: the device comprises a radio frequency signal transmitter, an ultrasonic receiver, a timer and a first processor;

the radio frequency signal transmitter is suitable for transmitting radio frequency signals to at least 3 anchor nodes;

the ultrasonic receiver is suitable for respectively receiving the ultrasonic wave transmitted by each anchor node;

the timer is suitable for acquiring the transmission time of the ultrasonic wave transmitted by each anchor node to the mobile equipment;

the first processor is suitable for controlling the radio frequency signal transmitter to transmit radio frequency signals, controlling the ultrasonic receiver to receive ultrasonic waves transmitted by each anchor node respectively, calculating the distance between each anchor node and the mobile device according to the transmission time and the transmission speed of the ultrasonic waves acquired by the timer, and determining the position coordinates of the mobile device according to the position coordinates of each anchor node and the distance between each anchor node and the mobile device.

Optionally, the number of the radio frequency signal transmitters is one, the number of the ultrasonic receivers is the same as that of the anchor nodes, the radio frequency signal transmitters are adapted to simultaneously transmit the same radio frequency signal to different anchor nodes, the ultrasonic receivers are adapted to receive the ultrasonic signals transmitted by the corresponding anchor nodes, and the ultrasonic signals received by different ultrasonic receivers are different.

Optionally, the radio frequency signal transmitter and the ultrasonic receiver are both one, the radio frequency signal transmitter is adapted to sequentially transmit different radio frequency signals to different anchor nodes, the ultrasonic signals transmitted by different anchor nodes are the same, and the interval time between two adjacent radio frequency signals transmitted by the radio frequency signal transmitter is long enough to enable the ultrasonic receiver to receive the ultrasonic signals transmitted by each anchor node in the same sequence.

Optionally, when the radio frequency signal transmitter transmits a radio frequency signal, the timer starts timing; and when the ultrasonic receiver receives the ultrasonic signal, the timer stops timing, and the time acquired by the timer is used as the transmission time of the ultrasonic wave transmitted to the mobile equipment.

The embodiment of the invention also provides mobile equipment which comprises the indoor positioning device.

An embodiment of the present invention further provides an indoor positioning system of a mobile device, where the indoor positioning system of the mobile device includes: the mobile device and at least 3 anchor nodes;

the anchor node is adapted to transmit ultrasonic waves to the mobile device upon triggering of the radio frequency signal.

An embodiment of the present invention further provides an anchor node, where the anchor node includes: the system comprises a radio frequency signal receiver, an ultrasonic transmitter and a second processor;

the radio frequency signal receiver is suitable for receiving radio frequency signals transmitted by the mobile equipment;

the ultrasonic transmitter is suitable for transmitting corresponding ultrasonic waves under the control of the second processor after the radio-frequency signal receiver receives the radio-frequency signals;

and the second processor is suitable for controlling the ultrasonic transmitter to transmit a corresponding ultrasonic signal according to the received radio frequency signal.

Compared with the prior art, the embodiment of the invention has the beneficial effects that:

sending radio frequency signals to at least 3 anchor nodes by mobile equipment, respectively receiving ultrasonic waves sent by each anchor node by the mobile equipment, sending the ultrasonic waves by the corresponding anchor node under the trigger of the radio frequency signals, acquiring the transmission time of the ultrasonic waves sent by each anchor node transmitted to the mobile equipment, calculating the distance between each anchor node and the mobile equipment according to the transmission time corresponding to each ultrasonic wave and the transmission speed of the ultrasonic waves, and then determining the position coordinate of the mobile equipment according to the position coordinate of each anchor node and the distance between each anchor node and the mobile equipment, thereby realizing the indoor positioning of the mobile equipment based on the ultrasonic technology, and ensuring that the ultrasonic waves are not interfered by other signals in the surrounding environment and have good propagation directionality, and the embodiment of the invention ensures that the ultrasonic waves received respectively do not have interference, therefore, the accuracy of indoor positioning of the mobile equipment can be improved.

Furthermore, the number of the anchor nodes is increased, so that the indoor positioning accuracy of the mobile equipment is improved, and particularly, the positioning accuracy can still be ensured when the transmission of radio frequency signals or ultrasonic waves is influenced by obstacles in the space where the mobile equipment is located.

Drawings

Fig. 1 is a scene diagram of indoor positioning of a mobile device in an embodiment of the present invention;

fig. 2 is a schematic structural diagram of an indoor positioning apparatus of a mobile device in an embodiment of the present invention;

fig. 3 is a schematic structural diagram of an anchor node for indoor positioning of a mobile device in an embodiment of the present invention;

fig. 4 is a schematic structural diagram of an indoor positioning system of a mobile device in an embodiment of the present invention;

fig. 5 is a flowchart of an indoor positioning method of a mobile device in an embodiment of the present invention;

fig. 6 is a flowchart of an indoor positioning method of a mobile device in an embodiment of the present invention;

fig. 7 is a flowchart of an indoor positioning method of a mobile device in an embodiment of the present invention.

Detailed Description

As described above, the solutions for positioning the mobile device indoors are bluetooth technology, infrared technology, ultra wideband technology and wireless network technology, however, these positioning solutions have the problem of inaccurate positioning.

According to the embodiment of the invention, radio frequency signals are sent to at least 3 anchor nodes through mobile equipment, the mobile equipment respectively receives ultrasonic waves sent by each anchor node, the ultrasonic waves are sent by the corresponding anchor node under the trigger of the radio frequency signals, the transmission time of the ultrasonic waves sent by each anchor node to the mobile equipment is obtained, the distance between each anchor node and the mobile equipment is calculated according to the transmission time corresponding to each ultrasonic wave and the transmission speed of the ultrasonic waves, and the position coordinate of the mobile equipment is determined according to the position coordinate of each anchor node and the distance between each anchor node and the mobile equipment, so that the indoor positioning of the mobile equipment based on an ultrasonic technology is realized, and the indoor positioning accuracy of the mobile equipment is improved.

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.

Fig. 1 is a scene diagram of indoor positioning of a mobile device according to an embodiment of the present invention. As shown in fig. 1, M represents a mobile device to be located, and in a specific implementation, the mobile device needs to obtain its own position to provide reference or assist human-computer interaction for its next position movement.

As shown in fig. 1, A, B, C and D each represent an anchor node adapted to assist mobile device M in locating its position in three-dimensional space. In one implementation, when a three-dimensional coordinate system is established in a specific indoor space, the specific position of the anchor node is fixed, i.e., the three-dimensional coordinate values of the anchor node are known, and the anchor nodes A, B, C and D in fig. 1 are not fixed on the same plane.

It should be noted that fig. 1 only shows a case where the number of anchor nodes is 4, and when more than 4 anchor nodes are used, the technical solution in the embodiment of the present invention may be adopted to obtain the three-dimensional position coordinates of the mobile device to be positioned, where all anchor nodes are required to be not in the same plane. In the actual positioning requirement, only the two-dimensional position coordinate of the mobile equipment to be positioned is needed to be obtained, and the position of the mobile equipment can be assisted to be positioned by at least 3 anchor nodes, but when the two-dimensional position coordinate composed of the length and the width of the mobile equipment is obtained by using the method, the 3 anchor nodes for assisting are required to be positioned at the same height, and the 3 anchor nodes are required to be positioned on at least two straight lines.

For example, assuming that the mobile device M to be positioned in fig. 1 is an intelligent robot, the intelligent robot moves on the ground, and the coordinate values of two dimensions of the intelligent robot can be calculated by using the 3 anchor nodes A, B and C, when the 3 anchor nodes A, B and C are required to be at the same height (the z coordinate values of A, B and C in fig. 1 are equal) and the 3 anchor nodes are located on at least two straight lines, the x coordinate and the y coordinate of the intelligent robot can be calculated by using the 3 anchor nodes A, B and C, so that the position of the intelligent robot on the indoor ground can be determined.

In particular implementation, at least 3 anchor nodes can be used to obtain the two-dimensional position coordinate of the mobile device, and at least 4 anchor nodes can be used to obtain the three-dimensional position coordinate of the mobile device. Specifically, more than 3 anchor nodes may be used to obtain two-dimensional location coordinates of the mobile device, where all anchor nodes are required not to be on a straight line; more than 4 anchor nodes may be used to obtain three-dimensional location coordinates of the mobile device, where all anchor nodes are required to be not on one plane. The above calculation method for improving the accuracy of the mobile device location by using more anchor nodes is described in detail below, and is not described herein again.

Fig. 2 is a schematic structural diagram of an indoor positioning apparatus of a mobile device in an embodiment of the present invention. The indoor positioning apparatus 20 of the mobile device shown in fig. 2 may include: a radio frequency signal transmitter 201, an ultrasonic receiver 202, a timer 203 and a first processor 204;

the radio frequency signal transmitter 201 is adapted to transmit radio frequency signals to at least 3 anchor nodes;

the ultrasonic receiver 202 is adapted to receive the ultrasonic waves transmitted by each anchor node respectively;

the timer 203 is adapted to obtain the transmission time of the ultrasonic wave transmitted by each anchor node to the mobile device;

the first processor 204 is adapted to control the radio frequency signal transmitter 201 to transmit a radio frequency signal, control the ultrasonic receiver 202 to receive an ultrasonic wave transmitted by each anchor node, calculate a distance between each anchor node and a mobile device according to the transmission time and the transmission speed of the ultrasonic wave acquired by the timer 203, and determine a position coordinate of the mobile device according to the position coordinate of each anchor node and the distance between each anchor node and the mobile device.

In a specific implementation, the number of the radio frequency signal transmitters 201 may be one, and the number of the ultrasonic receivers 202 is the same as the number of the anchor nodes. The radio frequency signal transmitter 201 is adapted to simultaneously transmit the same radio frequency signal to different anchor nodes, the ultrasonic receiver 202 is adapted to receive the ultrasonic signal transmitted by the corresponding anchor node, and the ultrasonic signals received by different ultrasonic receivers 202 are different.

In this embodiment, the anchor node is adapted to transmit an ultrasonic signal to assist the mobile device in performing indoor positioning.

In particular implementations, different ultrasound receivers 202 may receive ultrasound signals at different frequencies to distinguish between different ultrasound waves transmitted by corresponding anchor nodes.

The indoor positioning device 20 of the mobile equipment is arranged to perform indoor positioning of the mobile equipment, ultrasonic signals received by the ultrasonic receiver 202 of the indoor positioning device 20 of the mobile equipment come from different anchor nodes with different ultrasonic signal frequencies in pairs to respectively receive ultrasonic signals sent by corresponding anchor nodes to the mobile equipment, so that the positioning device 20 can determine which corresponding anchor node each ultrasonic signal comes from, further ensure that a timer 203 accurately obtains the time for sending the ultrasonic wave sent by the corresponding anchor node to the mobile equipment, finally enable the first processor 204 to calculate the distance between each anchor node and the mobile equipment according to the time obtained by the timer 203 and the transmission speed of the ultrasonic wave, calculate the distance between each anchor node and the mobile equipment according to the position coordinates of each anchor node and the distance between each anchor node and the mobile equipment, determining location coordinates of the mobile device.

In a specific implementation, the radio frequency signal transmitter 201 and the ultrasonic receiver 202 may be both provided. The radio frequency signal transmitter 201 is adapted to sequentially transmit different radio frequency signals to different anchor nodes at intervals, and the ultrasonic signals transmitted by different anchor nodes are the same. The interval time between two adjacent radio frequency signals transmitted by the radio frequency signal transmitter 201 is long enough to enable the ultrasonic receiver 202 to receive the ultrasonic signals transmitted by each of the anchor nodes in the same sequence.

In a specific implementation, when the rf signal transmitter 201 transmits an rf signal, the timer 203 starts to time; when the ultrasonic receiver 202 receives an ultrasonic signal, the timer 203 stops counting time, and the time acquired by the timer 203 is used as the transmission time of the ultrasonic wave to the mobile device.

Specifically, the radio frequency signal transmitter 201 sequentially and respectively sends different radio frequency signals to all anchor nodes at intervals, the ultrasonic signals sent by different anchor nodes are the same, the frequency of the radio frequency signal sent each time is the same, but the radio frequency signal sent each time is carried with different information corresponding to each different anchor node to ensure that only one anchor node is triggered each time, so that the radio frequency signal triggers the corresponding anchor node to send the ultrasonic signal to the ultrasonic receiver 202, and the sequence of the ultrasonic signal sent by the anchor node received by the ultrasonic receiver 202 is the same as the sequence of the radio frequency signal sent by the radio frequency signal transmitter 201. For example, referring to fig. 1, the radio frequency signal transmitter 201 of the mobile device M transmits radio frequency signals to the anchor nodes A, B, C and D in sequence, wherein the interval time between adjacent transmitted radio frequency signals may be set to be the same, each transmitted radio frequency signal triggers only the anchor node A, B, C or D, the anchor nodes A, B, C and D respectively transmit the same ultrasonic wave under the triggering of the radio frequency signals, so that the ultrasonic wave receiver 202 of the mobile device M also receives the ultrasonic wave signals transmitted by the anchor nodes A, B, C and D in sequence in the same order.

In a specific implementation, the interval time may be set to be greater than or equal to a quotient obtained by dividing the longest distance between two points in the indoor space where the mobile device is located by the transmission speed of the ultrasonic wave. In the embodiment of the present invention, by setting the interval time to be long enough, specifically, to be greater than the quotient of the longest distance between two points in the indoor space where the mobile device is located and the ultrasonic transmission speed, it is ensured that when the positioning device 20 only including one radio frequency signal transmitter 201 and one ultrasonic receiver 202 is used, the sequence in which the ultrasonic receiver 202 receives the ultrasonic signals is the same as the sequence in which the radio frequency signal transmitter 201 transmits the radio frequency signals, so that the ultrasonic receiver 202 does not generate interference between the received ultrasonic signals, and the positioning accuracy is ensured.

Since the propagation speed of the radio frequency signal is equal to the speed of light, the time for the radio frequency signal to be transmitted from the mobile device to the anchor node is negligible, and the time recorded by the timer 203 from the time when the radio frequency signal is sent by the radio frequency signal transmitter 201 to the time when the ultrasonic wave signal is received by the ultrasonic wave receiver 202 may be taken as the transmission time for the ultrasonic wave to be transmitted to the mobile device.

The indoor positioning device 20 of the mobile equipment is arranged to perform indoor positioning on the mobile equipment, the indoor positioning device 20 of the mobile equipment is provided with a radio frequency signal transmitter 201 and an ultrasonic receiver 202, the radio frequency signal transmitter 201 sequentially transmits different radio frequency signals to different anchor nodes at intervals, so that the ultrasonic receiver 202 respectively receives ultrasonic signals transmitted by the anchor nodes in the same sequence, the first processor 204 calculates the distance between the corresponding anchor node and the mobile equipment by using correct ultrasonic transmission time, and the position coordinate of the mobile equipment can be accurately calculated. In addition, since only one ultrasonic receiver 202 is used, the production cost is reduced, and the volume of the apparatus is reduced.

In a specific implementation, the radio frequency signal may be an infrared, bluetooth, or wifi signal.

In a specific implementation, when the mobile device is an intelligent robot, the indoor positioning device 20 may be used to obtain a two-dimensional position coordinate of a plane where the intelligent robot is located, and if the position coordinate is a two-dimensional coordinate composed of a length and a width, heights of different anchor nodes used for auxiliary positioning are required to be the same, and all the anchor nodes are no longer on the same straight line.

Fig. 3 is a schematic structural diagram of an anchor node for indoor positioning of a mobile device according to an embodiment of the present invention. The anchor node 30, as shown in fig. 3, may include: a radio frequency signal receiver 301, an ultrasonic transmitter 302, and a second processor 303;

the radio frequency signal receiver 301 is adapted to receive a radio frequency signal transmitted from a mobile device;

the ultrasonic transmitter 302 is adapted to transmit corresponding ultrasonic waves under the control of the second processor 303 after the radio frequency signal receiver 301 receives the radio frequency signal;

the second processor 303 is adapted to control the ultrasonic transmitter 301 to transmit a corresponding ultrasonic signal according to the received radio frequency signal.

In a specific implementation, the anchor node 30 is used to assist a mobile device to be located in an indoor location, and has a structure as shown in fig. 3.

In a specific implementation, when the mobile device to be located needs to determine a two-dimensional position coordinate, the two-dimensional coordinate of the mobile device can be determined by using at least three anchor nodes 30, where a plane where the three anchor nodes 30 are located is parallel to a plane where the mobile device to be located is located, and the 3 anchor nodes are located on at least two straight lines. For example, when the mobile device is a smart robot, to determine the two-dimensional position coordinates of the smart robot on the ground, which are composed of a length and a width, 3 anchor nodes 30 are located at the same height, and the 3 anchor nodes are located on at least two straight lines.

In addition, in a specific implementation, when the two-dimensional position coordinate of the mobile device is determined by using more than three anchor nodes 30, the positioning error may be further reduced, and specifically, after the distance between each anchor node and the mobile device is obtained, the two-dimensional position coordinate of the mobile device may be calculated by using a least square method, where the calculation method is described in detail below and is not repeated here.

In a specific implementation, when a mobile device to be located needs to determine three-dimensional position coordinates, the three-dimensional position coordinates can be determined using 4 anchor nodes 30, where the 4 anchor nodes are not in the same plane.

In addition, in a specific implementation, the number of anchor nodes 30 (i.e., more than 4 anchor nodes) may be increased to determine the three-dimensional position coordinate of the mobile device, so as to reduce the positioning error, and specifically, after the distance between each anchor node and the mobile device is obtained, the three-dimensional position coordinate of the mobile device may be calculated by using a least square method, which is detailed below and is not described herein again.

In a specific implementation, when the anchor node 30 is used to assist in determining the position coordinate of the mobile device in this embodiment, an indoor positioning apparatus used by the mobile device is the same as the indoor positioning apparatus 20 shown in fig. 2, and therefore, how to obtain the distance from each anchor node to the mobile device is not described herein again.

Fig. 4 is a schematic structural diagram of an indoor positioning system of a mobile device according to an embodiment of the present invention. The indoor positioning system 40 of the mobile device shown in fig. 4 may include a mobile device 401 and anchor nodes 402, where the number of the anchor nodes 402 is at least 3. Wherein the mobile device 401 may employ the indoor positioning apparatus 20 of the mobile device shown in fig. 2, and the anchor node 402 is the same as the anchor node 30 shown in fig. 3.

In a specific implementation, the positioning apparatus employed by the mobile device 401 may include: a radio frequency signal transmitter 201, an ultrasonic receiver 202, a timer 203 and a first processor 204;

the radio frequency signal transmitter 201 is adapted to transmit radio frequency signals to at least 3 anchor nodes;

the ultrasonic receiver 202 is adapted to receive the ultrasonic waves transmitted by each anchor node respectively;

the timer 203 is adapted to obtain the transmission time of the ultrasonic wave transmitted by each anchor node to the mobile device;

the first processor 204 is adapted to control the radio frequency signal transmitter 201 to transmit a radio frequency signal, control the ultrasonic receiver 202 to receive an ultrasonic wave transmitted by each anchor node, calculate a distance between each anchor node and a mobile device according to the transmission time and the transmission speed of the ultrasonic wave acquired by the timer 203, and determine a position coordinate of the mobile device according to the position coordinate of each anchor node and the distance between each anchor node and the mobile device.

In a specific implementation, the anchor node 402 is the same as the anchor node 30 shown in fig. 3, i.e., the anchor node 402 may include: a radio frequency signal receiver 301, an ultrasonic transmitter 302, and a second processor 303;

the radio frequency signal receiver 301 is adapted to receive a radio frequency signal transmitted from a mobile device;

the ultrasonic transmitter 302 is adapted to transmit corresponding ultrasonic waves under the control of the second processor 303 after the radio frequency signal receiver 301 receives the radio frequency signal;

the second processor 303 is adapted to control the ultrasonic transmitter 301 to transmit a corresponding ultrasonic signal according to the received radio frequency signal.

In a specific implementation, the radio frequency signal may be an infrared, bluetooth, or wifi signal.

In a specific implementation, the number of the radio frequency signal transmitters 201 may be one, and the number of the ultrasonic receivers 202 is the same as that of the anchor nodes. The radio frequency signal transmitter 201 is adapted to transmit the same radio frequency signal to different anchor nodes at the same time, the corresponding ultrasonic receiver 202 is adapted to receive the ultrasonic signal transmitted by the corresponding anchor node 30, and the ultrasonic signals received by the different ultrasonic receivers 202 are different.

In a specific implementation, different ultrasound receivers 202 may receive ultrasound signals of different corresponding frequencies to respectively receive different ultrasound waves transmitted by the anchor node 30.

In the embodiment of the present invention, indoor positioning is performed by setting an indoor positioning system 40 of a mobile device, the indoor positioning system 40 of the mobile device adopts the indoor positioning apparatus 20 of the mobile device shown in fig. 2, the radio frequency signal transmitter 201 of the indoor positioning apparatus 20 of the mobile device 401 transmits a radio frequency signal to trigger the radio frequency signal receiver 301 of the anchor node 402 to receive the radio frequency signal, the anchor node 402 transmits a corresponding ultrasonic signal under the control of the second processor 303, and any two ultrasonic signals are different, so that different ultrasonic receivers 202 respectively receive the ultrasonic signals transmitted by the ultrasonic transmitter 302 to the mobile device 401, thereby enabling the timer 203 of the mobile device 401 to determine from which corresponding anchor node each ultrasonic signal comes, and obtain the time for transmitting the ultrasonic wave transmitted by the corresponding anchor node 402 to the mobile device 401, finally, the first processor 204 calculates the distance between each anchor node 402 and the mobile device 401 according to the time acquired by the timer 203 and the transmission speed of the ultrasonic wave, and determines the position coordinate of the mobile device 401 according to the position coordinate of each anchor node 402 and the distance between each anchor node 402 and the mobile device 401.

In a specific implementation, the radio frequency signal transmitter 201 and the ultrasonic receiver 202 may be both provided. The radio frequency signal transmitter 201 is adapted to send different radio frequency signals to different anchor nodes 402 at intervals in sequence, the ultrasonic signals sent by different anchor nodes 402 are the same, and the interval time between two adjacent radio frequency signals sent by the radio frequency signal transmitter 201 is long enough to enable the ultrasonic receiver 202 to receive the ultrasonic signals sent by each anchor node 402 in the same sequence.

In a specific implementation, when the rf signal transmitter 201 transmits an rf signal, the timer 203 starts to time; when the ultrasonic receiver 202 receives an ultrasonic signal, the timer 203 stops counting time, and the time acquired by the timer 203 is used as the transmission time of the ultrasonic wave to the mobile device 401.

Specifically, the radio frequency signal transmitter 201 sequentially and respectively sends different radio frequency signals to different anchor nodes 402 at intervals, each radio frequency signal has the same frequency, but different information corresponding to each different anchor node 402 is carried in the radio frequency signal to ensure that only one of the anchor nodes is triggered in each sending, so that the radio frequency signal triggers the corresponding anchor node 402 to send an ultrasonic signal to the ultrasonic receiver 202, and the sequence of the ultrasonic signal sent by the anchor node 402 and received by the ultrasonic receiver 202 is the same as the sequence of the radio frequency signal sent by the radio frequency signal transmitter 201. For example, referring to fig. 1, the radio frequency signal transmitter 201 of the mobile device M transmits radio frequency signals to the anchor nodes A, B, C and D in sequence, wherein the interval time between adjacent transmitted radio frequency signals may be set to be the same, each transmitted radio frequency signal triggers only the anchor node A, B, C or D, the radio frequency signal receiver 301 of the corresponding anchor node 402 receives the radio frequency signal, and the second processor 303 of the anchor node 402 controls the ultrasonic signal transmitter 302 to transmit ultrasonic waves, so that the sequence of the ultrasonic signals received by the ultrasonic receiver 202 of the mobile device M also comes from the anchor nodes A, B, C and D, respectively.

In a specific implementation, as shown in fig. 1, the interval time may be set to be greater than a quotient of a longest distance between two points in an indoor space where the mobile device is located and the ultrasonic transmission speed, so as to ensure that when the positioning device 20 composed of one radio frequency signal transmitter 201 and one ultrasonic receiver 202 is used, an order in which the ultrasonic receiver 202 receives the ultrasonic signals is the same as an order in which the radio frequency signal transmitter 201 transmits the radio frequency signals, that is, no interference is generated between the ultrasonic receiver 202 and the ultrasonic signals, and thus the positioning accuracy is ensured.

In a specific implementation, since the propagation speed of the radio frequency signal is equal to the speed of light, the time for the radio frequency signal to be transmitted from the mobile device to the anchor node 402 is negligible, and the time recorded by the timer 203 from the time when the radio frequency signal is transmitted by the radio frequency signal transmitter 201 to the time when the ultrasonic wave signal is received by the ultrasonic wave receiver 202 may be taken as the transmission time for the ultrasonic wave to be transmitted to the mobile device.

The embodiment of the present invention sets an indoor positioning system 40 of a mobile device to perform indoor positioning of the mobile device, where a mobile device 401 of the indoor positioning system 40 of the mobile device adopts an indoor positioning apparatus 20 of the mobile device shown in fig. 2, an anchor node 402 adopts an anchor node 30 shown in fig. 3, and the indoor positioning apparatus 20 of the mobile device 401 is composed of a radio frequency signal transmitter 201 and an ultrasonic receiver 202. The radio frequency signal transmitter 201 sequentially sends different radio frequency signals to different anchor nodes 402 at intervals, the radio frequency signal receiver 301 of the anchor node 402 receives the radio frequency signals, the second processor 303 controls the ultrasonic transmitter 302 to send ultrasonic signals under the trigger of the radio frequency signals, and as the radio frequency signals are sent at intervals under the control of the first processor 204, the ultrasonic receiver 202 also respectively receives the ultrasonic signals sent by the ultrasonic transmitter 302 in the same sequence, so that the first processor 204 obtains correct ultrasonic transmission time to calculate the distance between the corresponding anchor node 402 and the mobile device, and the position coordinate of the mobile device 401 can be accurately calculated. In addition, since only one ultrasonic receiver 202 is used, the production cost is reduced, and the volume of the apparatus is reduced.

In a specific implementation, when the mobile device 401 to be located needs to determine a two-dimensional position coordinate, the two-dimensional coordinate of the mobile device 401 can be determined by using at least three anchor nodes 402, where a plane where the three anchor nodes 402 are located is parallel to a plane where the mobile device 401 to be located is located, and the 3 anchor nodes are located on at least two straight lines. For example, when the mobile device 401 is a smart robot, to determine two-dimensional position coordinates of the smart robot on the ground, which are composed of a length and a width, 3 anchor nodes 402 are located at the same height, and the 3 anchor nodes 402 are located on at least two straight lines.

The method of calculating two-dimensional position coordinates using 3 anchor nodes 402 is briefly described below: when starting from the origin, a three-dimensional coordinate system is established by two mutually perpendicular x-axis, y-axis and z-axis, wherein the plane formed by the x-axis and the y-axis is parallel to the horizontal plane, and the z-axis is perpendicular to the horizontal plane. The position coordinates of 3 anchor nodes are known, and the coordinates of the anchor node 402 are (x)₁，y₁，z₁)，(x₂，y₂，z₂)，(x₃，y₃，z₃) The two-dimensional position coordinates (X, Y) of mobile device 401 are calculated using equations (1) and (2):

$X=\frac{\left|\begin{array}{cc}(d_1^2-d_2^2)-(x_1^2-x_2^2)-(y_1^2-y_2^2)& 2(y_2-y_1)\\ (d_1^2-d_3^2)-(x_1^2-x_3^2)-(y_1^2-y_3^2)& 2(y_3-y_1)\end{array}\right|}{\left|\begin{array}{cc}2(x_2-x_1)& 2(y_2-y_1)\\ 2(x_3-x_1)& 2(y_3-y_1)\end{array}\right|}---\left(1\right)$

$Y=\frac{\left|\begin{array}{cc}2(x_2-x_1)& (d_1^2-d_2^2)-(x_1^2-x_2^2)-(y_1^2-y_2^2)\\ 2(x_3-x_1)& (d_1^2-d_3^2)-(x_1^2-x_3^2)-(y_1^2-y_3^2)\end{array}\right|}{\left|\begin{array}{cc}2(x_2-x_1)& 2(y_2-y_1)\\ 2(x_3-x_1)& 2(y_3-y_1)\end{array}\right|}---\left(2\right)$

in addition, in a specific implementation, when more than three anchor nodes 402 are used to determine the two-dimensional position coordinate of the mobile device, an error caused by an obstacle existing in an indoor space may be reduced, and specifically, after a distance between each anchor node 402 and the mobile device 401 is obtained, the two-dimensional position coordinate of the mobile device 401 may be calculated by using a least square method, and taking 5 anchor nodes as an example, the two-dimensional position coordinate (X, Y) may be calculated by using formula (3):

$\left[\begin{array}{c}x\\ y\end{array}\right]=A^{-1}{\left(A^T\right)}^{-1}{A}^{T}B---\left(3\right)$

wherein, $A=\left[\begin{array}{cc}2(x_2-x_1)& 2(y_2-y_1)\\ 2(x_3-x_2)& 2(x_3-x_2)\\ 2(x_4-x_3)& 2(x_4-x_3)\\ 2(x_5-x_4)& 2(x_5-x_4)\end{array}\right];$

$B=\left[\begin{array}{c}\left(d_1^2-d_2^2\right)-\left(x_1^2-x_2^2\right)-\left(y_1^2-y_2^2\right)\\ \left(d_2^2-d_3^2\right)-\left(x_2^2-x_3^2\right)-\left(y_2^2-y_3^2\right)\\ \left(d_3^2-d_4^2\right)-\left(x_3^2-x_4^2\right)-\left(y_3^2-y_4^2\right)\\ \left(d_4^2-d_5^2\right)-\left(x_4^2-x_5^2\right)-\left(y_4^2-y_5^2\right)\end{array}\right]$

in one embodiment, a three-dimensional coordinate system is established starting from an origin with two mutually perpendicular x, y and z axes, wherein the plane formed by the x and y axes is parallel to a horizontal plane and the z axis is perpendicular to the horizontal plane. When the mobile device 401 to be located needs to determine three-dimensional position coordinates, its three-dimensional position coordinates can be determined using 4 anchor nodes 402, where the 4 anchor nodes 402 are not in the same plane. For example, the anchor node coordinates are respectively (x)₁，y₁，z₁)，(x₂，y₂，z₂)，(x₃，y₃，z₃)，(x₄，y₄，z₄) The three-dimensional position coordinates (X, Y, Z) of the mobile device may be calculated using equations (4), (5), and (6):

$X=\frac{\left|\begin{array}{ccc}\left(d_1^2-d_2^2\right)-\left(x_1^2-x_2^2\right)-\left(y_1^2-y_2^2\right)-\left(z_1^2-z_2^2\right)& 2\left(y_2-y_1\right)& 2\left(z_2-z_1\right)\\ \left(d_1^2-d_3^2\right)-\left(x_1^2-x_3^2\right)-\left(y_1^2-y_3^2\right)-\left(z_1^2-z_3^2\right)& 2\left(y_3-y_1\right)& 2\left(z_3-z_1\right)\\ \left(d_1^2-d_4^2\right)-\left(x_1^2-x_4^2\right)-\left(y_1^2-y_4^2\right)-\left(z_1^2-z_4^2\right)& 2\left(y_4-y_1\right)& 2\left(z_4-z_1\right)\end{array}\right|}{\left|\begin{array}{ccc}2\left(x_2-x_1\right)& 2\left(y_2-y_1\right)& 2\left(z_2-z_1\right)\\ 2\left(x_3-x_1\right)& 2\left(y_3-y_1\right)& 2\left(z_3-z_1\right)\\ 2\left(x_4-x_1\right)& 2\left(y_4-y_1\right)& 2\left(z_4-z_1\right)\end{array}\right|}---\left(4\right)$

$Y=\frac{\left|\begin{array}{ccc}2\left(x_2-x_1\right)& \left(d_1^2-d_2^2\right)-\left(x_1^2-x_2^2\right)-\left(y_1^2-y_2^2\right)-\left(z_1^2-z_2^2\right)& 2\left(z_2-z_1\right)\\ 2\left(x_3-x_1\right)& \left(d_1^2-d_3^2\right)-\left(x_1^2-x_3^2\right)-\left(y_1^2-y_3^2\right)-\left(z_1^2-z_3^2\right)& 2\left(z_3-z_1\right)\\ 2\left(x_4-x_1\right)& \left(d_1^2-d_4^2\right)-\left(x_1^2-x_4^2\right)-\left(y_1^2-y_4^2\right)-\left(z_1^2-z_4^2\right)& 2\left(z_4-z_1\right)\end{array}\right|}{\left|\begin{array}{ccc}2\left(x_2-x_1\right)& 2\left(y_2-y_1\right)& 2\left(z_2-z_1\right)\\ 2\left(x_3-x_1\right)& 2\left(y_3-y_1\right)& 2\left(z_3-z_1\right)\\ 2\left(x_4-x_1\right)& 2\left(y_4-y_1\right)& 2\left(z_4-z_1\right)\end{array}\right|}---\left(5\right)$

$Z=\frac{\left|\begin{array}{ccc}2\left(x_2-x_1\right)& 2\left(y_2-y_1\right)& \left(d_1^2-d_2^2\right)-\left(x_1^2-x_2^2\right)-\left(y_1^2-y_2^2\right)-\left(z_1^2-z_2^2\right)\\ 2\left(x_3-x_1\right)& 2\left(y_3-y_1\right)& \left(d_1^2-d_3^2\right)-\left(x_1^2-x_3^2\right)-\left(y_1^2-y_3^2\right)-\left(z_1^2-z_3^2\right)\\ 2\left(x_4-x_1\right)& 2\left(y_4-y_1\right)& \left(d_1^2-d_4^2\right)-\left(x_1^2-x_4^2\right)-\left(y_1^2-y_4^2\right)-\left(z_1^2-z_4^2\right)\end{array}\right|}{\left|\begin{array}{ccc}2\left(x_2-x_1\right)& 2\left(y_2-y_1\right)& 2\left(z_2-z_1\right)\\ 2\left(x_3-x_1\right)& 2\left(y_3-y_1\right)& 2\left(z_3-z_1\right)\\ 2\left(x_4-x_1\right)& 2\left(y_4-y_1\right)& 2\left(z_4-z_1\right)\end{array}\right|}---\left(6\right)$

in addition, in a specific implementation, the anchor nodes 402, that is, more than 4 anchor nodes, may be additionally used to determine the three-dimensional position coordinate of the mobile device 401, so as to reduce the positioning error, specifically, after the distance between each anchor node 402 and the mobile device 401 is obtained, the three-dimensional position coordinate of the mobile device may be calculated by using a least square method, and specifically, the three-dimensional position coordinate (X, Y, Z) may be calculated by using formula (7):

$\left[\begin{array}{c}x\\ y\\ z\end{array}\right]=A^{-1}{\left(A^T\right)}^{-1}{A}^{T}B---\left(7\right)$

wherein, $A=\left[\begin{array}{ccc}2(x_2-x_1)& 2(y_2-y_1)& 2(z_2-z_1)\\ .& .& .\\ .& .& .\\ .& .& .\\ 2(x_i-x_{i-1})& 2(y_i-y_{i-1})& 2(z_i-z_{i-1})\end{array}\right];$

$B=\left[\begin{array}{c}\left(d_1^2-d_2^2\right)-\left(x_1^2-x_2^2\right)-\left(y_1^2-y_2^2\right)-\left(z_1^2-x_2^2\right)\\ .\\ .\\ .\\ \left(d_{i-1}^2-d_i^2\right)-\left(x_{i-1}^2-x_i^2\right)-\left(y_{i-1}^2-y_i^2\right)-\left(z_{i-1}^2-x_i^2\right)\end{array}\right]$

in the indoor positioning system 40 of a mobile device according to the embodiment of the present invention, by using the mobile device 401 and the anchor node 402, the mobile device 401 uses the indoor positioning apparatus 20 of the mobile device shown in fig. 2, the anchor node 402 uses the anchor node 30 shown in fig. 3, the mobile device 401 sends radio frequency signals to at least 3 anchor nodes 402, the mobile device 401 receives ultrasonic waves sent by each anchor node 402, the ultrasonic waves are sent by the corresponding anchor node 402 under the trigger of the radio frequency signals, the mobile device 401 obtains the transmission time of the ultrasonic waves sent by each anchor node 402 to the mobile device, calculates the distance between each anchor node 402 and the mobile device 401 according to the transmission time corresponding to each ultrasonic wave and the transmission speed of the ultrasonic waves, and then calculates the distance between each anchor node 402 and the mobile device 401 according to the position coordinates of each anchor node 402 and the distance between each anchor node 402 and the mobile device 401, the location coordinates of mobile device 401 are determined to improve the accuracy of the indoor location of mobile device 401.

Fig. 5 is a flowchart of an indoor positioning method of a mobile device in an embodiment of the present invention. The indoor positioning method of the mobile device as shown in fig. 5 may include the steps of:

step S501: the mobile device transmits radio frequency signals to at least 3 anchor nodes.

Step S502: and the mobile equipment receives the ultrasonic wave sent by each anchor node respectively.

Step S503: and acquiring the transmission time of the ultrasonic wave transmitted by each anchor node to the mobile equipment.

Step S504: and calculating the distance between each anchor node and the mobile equipment according to the transmission time corresponding to each ultrasonic wave and the transmission speed of the ultrasonic wave.

Step S505: and determining the position coordinate of the mobile equipment according to the position coordinate of each anchor node and the distance between each anchor node and the mobile equipment.

The indoor positioning method of the mobile device of the present invention is further described in detail with reference to fig. 6 and 7.

Fig. 6 is a flowchart of an indoor positioning method of a mobile device in an embodiment of the present invention. The indoor positioning method of the mobile device as shown in fig. 6 may include the steps of:

step S601: the mobile device transmits the same radio frequency signal to all anchor nodes simultaneously.

In a specific implementation, the radio frequency signal includes: infrared, bluetooth, or wifi.

Step S602: and receiving different ultrasonic signals sent by each anchor node.

Step S603: and acquiring the transmission time of the ultrasonic wave transmitted by each anchor node to the mobile equipment.

Step S604: and calculating the distance between each anchor node and the mobile equipment according to the transmission time corresponding to each ultrasonic wave and the transmission speed of the ultrasonic wave.

In a specific implementation, since the transmission speed of the ultrasonic wave is known, and is generally 340m/s in the air, the distance between each anchor node and the mobile device can be calculated according to the transmission time corresponding to each ultrasonic wave and the transmission speed.

Step S605: and determining the position coordinate of the mobile equipment according to the position coordinate of each anchor node and the distance between each anchor node and the mobile equipment.

The method for calculating the position coordinate of the mobile device in the embodiment of the present invention is the same as the method described in the embodiment of fig. 4, that is, the formulas in formulas (1) to (7) are adopted according to specific situations, and details are not described here again.

In a specific implementation, a time difference between a time when the mobile device sends a radio frequency signal to the anchor node and a time when the mobile device receives the ultrasonic wave sent by the anchor node can be used as a transmission time when the ultrasonic wave sent by the anchor node is transmitted to the mobile device.

According to the embodiment of the invention, the mobile equipment simultaneously sends the same radio frequency signals to all anchor nodes, and respectively receives different ultrasonic signals sent by corresponding anchor nodes to the mobile equipment, so that the mobile equipment can determine which corresponding anchor node each ultrasonic signal comes from, accurately acquire the time for sending the ultrasonic wave sent by the corresponding anchor node to the mobile equipment, calculate the distance between each anchor node and the mobile equipment according to the time and the transmission speed of the ultrasonic wave, and then determine the position coordinate of the mobile equipment according to the position coordinate of each anchor node and the distance between each anchor node and the mobile equipment, thereby realizing improvement of the indoor positioning accuracy of the mobile equipment based on an ultrasonic technology.

In a specific implementation, when the mobile device is an intelligent robot and the position coordinates are two-dimensional coordinates composed of length and width, the heights of different anchor nodes are required to be the same, and all the anchor nodes are not on the same straight line, that is, are located on at least two straight lines.

In this embodiment, when determining the two-dimensional position coordinate or the three-dimensional position coordinate of the mobile device, the number of anchor nodes used and the indoor layout thereof are described with reference to the previous embodiment, and are not described herein again.

Fig. 7 is a flowchart of an indoor positioning method of a mobile device in an embodiment of the present invention. The indoor positioning method of the mobile device as shown in fig. 7 may include the steps of:

step S701: the mobile device transmits different radio frequency signals to all anchor nodes in sequence.

In a specific implementation, the ultrasonic signals sent by different anchor nodes are the same, and the interval time between two adjacent radio frequency signals sent by the mobile device is long enough to enable the mobile device to receive the ultrasonic signals sent by each anchor node in the same sequence.

In a specific implementation, the interval time is set to be greater than or equal to a quotient of the longest distance between two points in the indoor space where the mobile device is located and the transmission speed of the ultrasonic wave.

In a specific implementation, the radio frequency signal includes: infrared, bluetooth, or wifi.

Step S702: and the mobile equipment receives the ultrasonic wave sent by each anchor node respectively.

In a specific implementation, the mobile device sends the same radio frequency signals to all anchor nodes in sequence, and the interval time is long enough, so that the mobile device also receives the ultrasonic signals sent by the corresponding anchor nodes in the same sequence.

Step S703: and acquiring the transmission time of the ultrasonic wave transmitted by each anchor node to the mobile equipment.

In a specific implementation, a time difference between a time when the mobile device sends a radio frequency signal to the anchor node and a time when the mobile device receives the ultrasonic wave sent by the anchor node can be used as a transmission time when the ultrasonic wave sent by the anchor node is transmitted to the mobile device.

Step S704: and calculating the distance between each anchor node and the mobile equipment according to the transmission time corresponding to each ultrasonic wave and the transmission speed of the ultrasonic wave.

In a specific implementation, since the transmission speed of the ultrasonic wave is known, and is generally 340m/s in the air, the distance between each anchor node and the mobile device can be calculated according to the transmission time corresponding to each ultrasonic wave and the transmission speed.

Step S705: and determining the position coordinate of the mobile equipment according to the position coordinate of each anchor node and the distance between each anchor node and the mobile equipment.

The method for calculating the position coordinate of the mobile device in the embodiment of the present invention is the same as the method described in the embodiment of fig. 4, that is, the formulas in formulas (1) to (7) are adopted according to specific situations, and details are not described here again.

When the mobile equipment is an intelligent robot, the position coordinate is a two-dimensional coordinate formed by the length and the width, the heights of different anchor nodes are the same, and all the anchor nodes are at least positioned on two straight lines.

In this embodiment, the number of anchor nodes used and the indoor layout thereof when determining the two-dimensional position coordinate or the three-dimensional position coordinate of the mobile device are the same as those in the embodiment in fig. 4, and are not described herein again.

According to the embodiment of the invention, the mobile equipment sends different radio frequency signals to all anchor nodes at intervals in sequence to trigger the anchor nodes to send ultrasonic signals, the mobile equipment respectively receives corresponding ultrasonic waves sent by the anchor nodes in the same sequence to obtain the transmission time of the ultrasonic waves sent by each anchor node to the mobile equipment, the distance between each anchor node and the mobile equipment is calculated according to the transmission time corresponding to each ultrasonic wave and the transmission speed of the ultrasonic waves, and the position coordinate of the mobile equipment is determined according to the position coordinate of each anchor node and the distance between each anchor node and the mobile equipment, so that the accuracy of indoor positioning of the mobile equipment is improved based on an ultrasonic technology.

An embodiment of the present invention further provides a mobile device, where the mobile device employs the indoor positioning apparatus 20 of the mobile device as shown in fig. 2, that is, the mobile device may include: the radio frequency signal transmitter 201, the ultrasonic receiver 202, the timer 203 and the first processor 204 are omitted for brevity. The mobile device can obtain the position coordinates of the mobile device in the indoor space by using the indoor positioning device 20 of the mobile device, and provide position data for the next movement or human-computer interaction of the mobile device.

The mobile device of the embodiment of the present invention may be an intelligent robot or other mobile devices that need to be located, and is not limited herein.

Those skilled in the art will understand that some of the steps in the indoor positioning method of the mobile device in the above embodiments, and the first processor, the second processor and the timer may be implemented by a program to instruct related hardware, where the program may be stored in a computer-readable storage medium, and the storage medium may include: ROM, RAM, magnetic or optical disks, and the like.

Although the present invention is disclosed above, the present invention is not limited thereto. Various changes and modifications may be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

Claims (14)

1. An indoor positioning method of a mobile device, comprising:

the mobile equipment sends radio frequency signals to at least 3 anchor nodes;

the mobile equipment receives ultrasonic waves sent by each anchor node respectively, and the ultrasonic waves are sent by the corresponding anchor nodes under the triggering of the radio frequency signals;

acquiring transmission time of ultrasonic waves transmitted by each anchor node to the mobile equipment;

calculating the distance between each anchor node and the mobile equipment according to the transmission time corresponding to each ultrasonic wave and the transmission speed of the ultrasonic wave;

and determining the position coordinate of the mobile equipment according to the position coordinate of each anchor node and the distance between each anchor node and the mobile equipment.

2. The indoor positioning method of the mobile device according to claim 1, wherein the mobile device transmits radio frequency signals to at least 3 anchor nodes, and the mobile device receives ultrasonic waves transmitted by each of the anchor nodes, and the ultrasonic waves are transmitted by the corresponding anchor nodes under the trigger of the radio frequency signals, and the method comprises:

the mobile equipment simultaneously sends the same radio frequency signal to all anchor nodes and receives different ultrasonic signals sent by each anchor node.

3. The indoor positioning method of a mobile device according to claim 1, wherein the mobile device receives an ultrasonic wave transmitted by each anchor node, and the ultrasonic wave is transmitted by the corresponding anchor node under the trigger of the radio frequency signal, and the method comprises:

the mobile equipment sends different radio frequency signals to all anchor nodes in sequence, the ultrasonic signals sent by different anchor nodes are the same, and the interval time between two adjacent radio frequency signals sent by the mobile equipment is long enough to enable the mobile equipment to receive the ultrasonic signals sent by each anchor node in the same sequence.

4. An indoor positioning method of a mobile device according to claim 3, wherein the interval time is greater than or equal to a quotient obtained by dividing the longest distance between two points in the indoor space where the mobile device is located by the transmission speed of the ultrasonic wave.

5. The method for indoor positioning of a mobile device according to claim 1, wherein said obtaining a transmission time of an ultrasonic wave transmitted by each of said anchor nodes to said mobile device comprises: and taking the time difference between the time when the mobile device sends the radio frequency signal to the anchor node and the time when the mobile device receives the ultrasonic wave sent by the anchor node as the transmission time when the ultrasonic wave sent by the anchor node is transmitted to the mobile device.

6. The indoor positioning method of a mobile device of claim 1, wherein the radio frequency signal comprises: infrared, bluetooth, or wifi.

7. The indoor positioning method of a mobile device according to claim 1, wherein the mobile device is an intelligent robot, the position coordinates are two-dimensional coordinates consisting of a length and a width, heights of different anchor nodes are the same, and all the anchor nodes are located on at least two straight lines.

8. An indoor positioning apparatus of a mobile device, comprising: the device comprises a radio frequency signal transmitter, an ultrasonic receiver, a timer and a first processor;

the radio frequency signal transmitter is suitable for transmitting radio frequency signals to at least 3 anchor nodes;

the ultrasonic receiver is suitable for respectively receiving the ultrasonic wave transmitted by each anchor node;

the timer is suitable for acquiring the transmission time of the ultrasonic wave transmitted by each anchor node to the mobile equipment;

the first processor is suitable for controlling the radio frequency signal transmitter to transmit radio frequency signals, controlling the ultrasonic receiver to receive ultrasonic waves transmitted by each anchor node respectively, calculating the distance between each anchor node and the mobile device according to the transmission time and the transmission speed of the ultrasonic waves acquired by the timer, and determining the position coordinates of the mobile device according to the position coordinates of each anchor node and the distance between each anchor node and the mobile device.

9. The indoor positioning apparatus for mobile device of claim 8, wherein the number of the radio frequency signal transmitters is one, the number of the ultrasonic receivers is the same as the number of the anchor nodes, the radio frequency signal transmitters are adapted to simultaneously transmit the same radio frequency signal to different anchor nodes, the ultrasonic receivers are adapted to receive the ultrasonic signals transmitted by the corresponding anchor nodes, and the ultrasonic signals received by different ultrasonic receivers are different.

10. The indoor positioning apparatus for mobile device of claim 8, wherein said radio frequency signal transmitter and said ultrasonic receiver are both one, said radio frequency signal transmitter is adapted to sequentially transmit different radio frequency signals to different anchor nodes, the ultrasonic signals transmitted by different anchor nodes are the same, and the interval between two adjacent radio frequency signals transmitted by said radio frequency signal transmitter is long enough to allow said ultrasonic receiver to receive the ultrasonic signals transmitted by each of said anchor nodes in the same sequence.

11. The indoor positioning apparatus of a mobile device according to claim 10, wherein the timer starts timing when the radio frequency signal transmitter transmits a radio frequency signal; and when the ultrasonic receiver receives the ultrasonic signal, the timer stops timing, and the time acquired by the timer is used as the transmission time of the ultrasonic wave transmitted to the mobile equipment.

12. A mobile device, characterized in that it comprises an indoor positioning device according to any one of claims 8 to 11.

13. An indoor positioning system for a mobile device, comprising: the mobile device of claim 12 and at least 3 anchor nodes;

the anchor node is adapted to transmit ultrasonic waves to the mobile device upon triggering of the radio frequency signal.

14. An anchor node, comprising: the system comprises a radio frequency signal receiver, an ultrasonic transmitter and a second processor;

the radio frequency signal receiver is suitable for receiving radio frequency signals transmitted by the mobile equipment;

the ultrasonic transmitter is suitable for transmitting corresponding ultrasonic waves under the control of the second processor after the radio-frequency signal receiver receives the radio-frequency signals;

and the second processor is suitable for controlling the ultrasonic transmitter to transmit a corresponding ultrasonic signal according to the received radio frequency signal.